diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -17,7 +17,7 @@
     hooks:
       - id: codespell
         name: Check source code spelling
-        exclude: ^(swh/loader/package/.*[/]+tests/data/.*)$
+        exclude: ^(swh/loader/(package/.*[/]+|core)/tests/data/.*)$
         args: [-L crate]
         entry: codespell --ignore-words-list=iff
         stages: [commit]
diff --git a/swh/loader/core/loader.py b/swh/loader/core/loader.py
--- a/swh/loader/core/loader.py
+++ b/swh/loader/core/loader.py
@@ -3,12 +3,14 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
+import base64
 import datetime
 import hashlib
 import logging
 import os
 import time
 from typing import Any, ContextManager, Dict, Iterable, List, Optional, Union
+from urllib.parse import urlparse
 
 import sentry_sdk
 
@@ -16,6 +18,7 @@
 from swh.core.statsd import Statsd
 from swh.loader.core.metadata_fetchers import CredentialsType, get_fetchers_for_lister
 from swh.loader.exception import NotFound
+from swh.loader.package.utils import get_url_body
 from swh.model.model import (
     BaseContent,
     Content,
@@ -29,8 +32,11 @@
     Sha1Git,
     SkippedContent,
     Snapshot,
+    SnapshotBranch,
+    TargetType,
 )
 from swh.storage import get_storage
+from swh.storage.algos.snapshot import snapshot_get_latest
 from swh.storage.interface import StorageInterface
 from swh.storage.utils import now
 
@@ -273,7 +279,7 @@
         """
         return True
 
-    def store_data(self):
+    def store_data(self) -> None:
         """Store fetched data in the database.
 
         Should call the :func:`maybe_load_xyz` methods, which handle the
@@ -640,3 +646,107 @@
         self.storage.snapshot_add([snapshot])
         self.flush()
         self.loaded_snapshot_id = snapshot.id
+
+
+class ContentLoader(BaseLoader):
+    """Basic loader for edge case content ingestion."""
+
+    visit_type = "content"
+
+    def __init__(self, *args, **kwargs):
+        self.fallback_urls: List[str] = kwargs.pop("fallback_urls", [])
+        integrity: Optional[str] = kwargs.pop("integrity", None)
+        if not integrity:
+            raise ValueError("Mandatory field 'integrity' missing.")
+        self.integrity: str = integrity
+        super().__init__(*args, **kwargs)
+        self.content: Optional[Content] = None
+        self.snapshot: Optional[Snapshot] = None
+        self.last_snapshot: Optional[Snapshot] = None
+
+    def prepare(self) -> None:
+        self.last_snapshot = snapshot_get_latest(self.storage, self.origin.url)
+
+    def fetch_data(self) -> bool:
+        """Retrieve the content file as a Content Object"""
+        urls = set([self.origin.url]) | set(self.fallback_urls)
+        data: Optional[bytes] = None
+        for url in urls:
+            url_ = urlparse(url)
+            self.log.debug(
+                "prepare; origin_url=%s fallback=%s scheme=%s path=%s",
+                self.origin.url,
+                url,
+                url_.scheme,
+                url_.path,
+            )
+            try:
+                data = get_url_body(url)
+                self.content = Content.from_data(data)
+
+                # Ensure content received matched the integrity field received
+                hash_algo, hash_value_b64 = self.integrity.split("-")
+                actual_hash = getattr(self.content, hash_algo.lower())
+                expected_hash_value = base64.decodebytes(hash_value_b64.encode())
+
+                # If that matches, we have found our content to ingest
+                if actual_hash == expected_hash_value:
+                    break
+                # otherwise continue
+            except NotFound:
+                continue
+
+        if not self.content:
+            raise NotFound(
+                f"Unknown origin {self.origin.url} and no fallback urls gave result."
+            )
+
+        return False
+
+    def process_data(self) -> bool:
+        """Build the snapshot out of the Content retrieved."""
+
+        filename = os.path.basename(self.origin.url)
+        assert self.content is not None
+        self.snapshot = Snapshot(
+            branches={
+                b"alias": SnapshotBranch(
+                    target=b"HEAD",
+                    target_type=TargetType.ALIAS,
+                ),
+                filename.encode("utf-8"): SnapshotBranch(
+                    target=self.content.sha1_git,  # FIXME: which hash?
+                    target_type=TargetType.CONTENT,
+                ),
+            }
+        )
+
+        return False
+
+    def store_data(self) -> None:
+        """Store newly retrieved Content and Snapshot."""
+        assert self.content is not None
+        self.storage.content_add([self.content])
+        assert self.snapshot is not None
+        self.storage.snapshot_add([self.snapshot])
+        self.loaded_snapshot_id = self.snapshot.id
+
+    def visit_status(self):
+        return "full" if self.content and self.snapshot is not None else "partial"
+
+    def load_status(self) -> Dict[str, Any]:
+        if self.snapshot is None:
+            load_status = "failed"
+        elif self.last_snapshot == self.snapshot:
+            load_status = "uneventful"
+        else:
+            load_status = "eventful"
+        return {
+            "status": load_status,
+        }
+
+    def cleanup(self) -> None:
+        self.log.debug("cleanup")
+
+    def save_data(self) -> None:
+        pass
diff --git a/swh/loader/core/tests/data/https_common-lisp.net/project_asdf_archives_asdf-3.3.5.lisp b/swh/loader/core/tests/data/https_common-lisp.net/project_asdf_archives_asdf-3.3.5.lisp
new file mode 100644
--- /dev/null
+++ b/swh/loader/core/tests/data/https_common-lisp.net/project_asdf_archives_asdf-3.3.5.lisp
@@ -0,0 +1,13873 @@
+;;; -*- mode: Lisp; Base: 10 ; Syntax: ANSI-Common-Lisp ; Package: CL-USER ; buffer-read-only: t; -*-
+;;; This is ASDF 3.3.5: Another System Definition Facility.
+;;;
+;;; Feedback, bug reports, and patches are all welcome:
+;;; please mail to <asdf-devel@common-lisp.net>.
+;;; Note first that the canonical source for ASDF is presently
+;;; <URL:http://common-lisp.net/project/asdf/>.
+;;;
+;;; If you obtained this copy from anywhere else, and you experience
+;;; trouble using it, or find bugs, you may want to check at the
+;;; location above for a more recent version (and for documentation
+;;; and test files, if your copy came without them) before reporting
+;;; bugs.  There are usually two "supported" revisions - the git master
+;;; branch is the latest development version, whereas the git release
+;;; branch may be slightly older but is considered `stable'
+
+;;; -- LICENSE START
+;;; (This is the MIT / X Consortium license as taken from
+;;;  http://www.opensource.org/licenses/mit-license.html on or about
+;;;  Monday; July 13, 2009)
+;;;
+;;; Copyright (c) 2001-2019 Daniel Barlow and contributors
+;;;
+;;; Permission is hereby granted, free of charge, to any person obtaining
+;;; a copy of this software and associated documentation files (the
+;;; "Software"), to deal in the Software without restriction, including
+;;; without limitation the rights to use, copy, modify, merge, publish,
+;;; distribute, sublicense, and/or sell copies of the Software, and to
+;;; permit persons to whom the Software is furnished to do so, subject to
+;;; the following conditions:
+;;;
+;;; The above copyright notice and this permission notice shall be
+;;; included in all copies or substantial portions of the Software.
+;;;
+;;; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+;;; EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+;;; MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+;;; NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+;;; LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+;;; OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+;;; WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+;;;
+;;; -- LICENSE END
+
+;;; The problem with writing a defsystem replacement is bootstrapping:
+;;; we can't use defsystem to compile it.  Hence, all in one file.
+
+#+genera
+(eval-when (:compile-toplevel :load-toplevel :execute)
+  (multiple-value-bind (system-major system-minor)
+      (sct:get-system-version)
+    (multiple-value-bind (is-major is-minor)
+	(sct:get-system-version "Intel-Support")
+      (unless (or (> system-major 452)
+		  (and is-major
+		       (or (> is-major 3)
+			   (and (= is-major 3) (> is-minor 86)))))
+	(error "ASDF requires either System 453 or later or Intel Support 3.87 or later")))))
+;;;; ---------------------------------------------------------------------------
+;;;; Handle ASDF package upgrade, including implementation-dependent magic.
+;;
+;; See https://bugs.launchpad.net/asdf/+bug/485687
+;;
+
+;; CAUTION: The definition of the UIOP/PACKAGE package MUST NOT CHANGE,
+;; NOT NOW, NOT EVER, NOT UNDER ANY CIRCUMSTANCE. NEVER.
+;; ... and the same goes for UIOP/PACKAGE-LOCAL-NICKNAMES.
+;;
+;; The entire point of UIOP/PACKAGE is to address the fact that the CL standard
+;; *leaves it unspecified what happens when a package is redefined incompatibly*.
+;; For instance, SBCL 1.4.2 will signal a full WARNING when this happens,
+;; throwing a wrench in upgrading code with ASDF itself, while continuing to
+;; export old symbols it now shouldn't as it also exports new ones,
+;; causing problems with code that relies on the new/current exports.
+;; CLISP and CCL also exports both sets of symbols, though without any WARNING.
+;; ABCL 1.6.1 will plainly ignore the new definition.
+;; Other implementations may do whatever they want and change their behavior at any time.
+;; ***Using DEFPACKAGE twice with different definitions is nasal-demon territory.***
+;;
+;; Thus we define UIOP/PACKAGE:DEFINE-PACKAGE with which packages can be defined
+;; in an upgrade-friendly way: the new definition is authoritative, and
+;; the package will define and export exactly those symbols in the new definition,
+;; no more and no fewer, whereas it is well-defined what happens to previous symbols.
+;; However, for obvious bootstrap reasons, we cannot use DEFINE-PACKAGE
+;; to define UIOP/PACKAGE itself, only DEFPACKAGE.
+;; Therefore, unlike the other packages in ASDF, UIOP/PACKAGE is immutable,
+;; now and forever. It is frozen for the aeons to come, like the CL package itself,
+;; to the same exact state it was defined at its inception, in ASDF 2.27 in 2013.
+;; The same goes for UIOP/PACKAGE-LOCAL-NICKNAMES, that we use internally.
+;;
+;; If you ever must define new symbols in this file, you can and must
+;; export them from a different package, possibly defined in the same file,
+;; say a package UIOP/PACKAGE* defined at the end of this file with DEFINE-PACKAGE,
+;; that might use :import-from to import the symbols from UIOP/PACKAGE,
+;; if you must somehow define them in UIOP/PACKAGE.
+
+(defpackage :uiop/package ;;; THOU SHALT NOT modify this definition, EVER. See explanations above.
+  (:use :common-lisp)
+  (:export
+   #:find-package* #:find-symbol* #:symbol-call
+   #:intern* #:export* #:import* #:shadowing-import* #:shadow* #:make-symbol* #:unintern*
+   #:symbol-shadowing-p #:home-package-p
+   #:symbol-package-name #:standard-common-lisp-symbol-p
+   #:reify-package #:unreify-package #:reify-symbol #:unreify-symbol
+   #:nuke-symbol-in-package #:nuke-symbol #:rehome-symbol
+   #:ensure-package-unused #:delete-package*
+   #:package-names #:packages-from-names #:fresh-package-name #:rename-package-away
+   #:package-definition-form #:parse-define-package-form
+   #:ensure-package #:define-package
+   ))
+
+(in-package :uiop/package)
+
+;;; package local nicknames feature.
+;;; This can't be deferred until common-lisp.lisp, where most such features are set.
+;;; ABCL and CCL already define this feature appropriately.
+;;; Seems to be unconditionally present for SBCL, ACL, and CLASP
+;;; Don't know about ECL, or others
+(eval-when (:load-toplevel :compile-toplevel :execute)
+  ;; ABCL pushes :package-local-nicknames without UIOP interfering,
+  ;; and Lispworks will do so
+  #+(or sbcl clasp)
+  (pushnew :package-local-nicknames *features*)
+  #+allegro
+  (let ((fname (find-symbol (symbol-name '#:add-package-local-nickname) '#:excl)))
+    (when (and fname (fboundp fname))
+      (pushnew :package-local-nicknames *features*))))
+
+;;; THOU SHALT NOT modify this definition, EVER, *EXCEPT* to add a new implementation.
+;; If you somehow need to modify the API in any way,
+;; you will need to create another, differently named, and just as immutable package.
+#+package-local-nicknames
+(defpackage :uiop/package-local-nicknames
+  (:use :cl)
+  (:import-from
+   #+allegro #:excl
+   #+sbcl #:sb-ext
+   #+(or clasp abcl ecl) #:ext
+   #+ccl #:ccl
+   #+lispworks #:hcl
+   #-(or allegro sbcl clasp abcl ccl lispworks ecl)
+   (error "Don't know from which package this lisp supplies the local-package-nicknames API.")
+   #:remove-package-local-nickname #:package-local-nicknames #:add-package-local-nickname)
+  (:export
+   #:add-package-local-nickname #:remove-package-local-nickname #:package-local-nicknames))
+
+;;;; General purpose package utilities
+
+(eval-when (:load-toplevel :compile-toplevel :execute)
+  (defun find-package* (package-designator &optional (error t))
+    (let ((package (find-package package-designator)))
+      (cond
+        (package package)
+        (error (error "No package named ~S" (string package-designator)))
+        (t nil))))
+  (defun find-symbol* (name package-designator &optional (error t))
+    "Find a symbol in a package of given string'ified NAME;
+unlike CL:FIND-SYMBOL, work well with 'modern' case sensitive syntax
+by letting you supply a symbol or keyword for the name;
+also works well when the package is not present.
+If optional ERROR argument is NIL, return NIL instead of an error
+when the symbol is not found."
+    (block nil
+      (let ((package (find-package* package-designator error)))
+        (when package ;; package error handled by find-package* already
+          (multiple-value-bind (symbol status) (find-symbol (string name) package)
+            (cond
+              (status (return (values symbol status)))
+              (error (error "There is no symbol ~S in package ~S" name (package-name package))))))
+        (values nil nil))))
+  (defun symbol-call (package name &rest args)
+    "Call a function associated with symbol of given name in given package,
+with given ARGS. Useful when the call is read before the package is loaded,
+or when loading the package is optional."
+    (apply (find-symbol* name package) args))
+  (defun intern* (name package-designator &optional (error t))
+    (intern (string name) (find-package* package-designator error)))
+  (defun export* (name package-designator)
+    (let* ((package (find-package* package-designator))
+           (symbol (intern* name package)))
+      (export (or symbol (list symbol)) package)))
+  (defun import* (symbol package-designator)
+    (import (or symbol (list symbol)) (find-package* package-designator)))
+  (defun shadowing-import* (symbol package-designator)
+    (shadowing-import (or symbol (list symbol)) (find-package* package-designator)))
+  (defun shadow* (name package-designator)
+    (shadow (list (string name)) (find-package* package-designator)))
+  (defun make-symbol* (name)
+    (etypecase name
+      (string (make-symbol name))
+      (symbol (copy-symbol name))))
+  (defun unintern* (name package-designator &optional (error t))
+    (block nil
+      (let ((package (find-package* package-designator error)))
+        (when package
+          (multiple-value-bind (symbol status) (find-symbol* name package error)
+            (cond
+              (status (unintern symbol package)
+                      (return (values symbol status)))
+              (error (error "symbol ~A not present in package ~A"
+                            (string symbol) (package-name package))))))
+        (values nil nil))))
+  (defun symbol-shadowing-p (symbol package)
+    (and (member symbol (package-shadowing-symbols package)) t))
+  (defun home-package-p (symbol package)
+    (and package (let ((sp (symbol-package symbol)))
+                   (and sp (let ((pp (find-package* package)))
+                             (and pp (eq sp pp))))))))
+
+
+(eval-when (:load-toplevel :compile-toplevel :execute)
+  (defun symbol-package-name (symbol)
+    (let ((package (symbol-package symbol)))
+      (and package (package-name package))))
+  (defun standard-common-lisp-symbol-p (symbol)
+    (multiple-value-bind (sym status) (find-symbol* symbol :common-lisp nil)
+      (and (eq sym symbol) (eq status :external))))
+  (defun reify-package (package &optional package-context)
+    (if (eq package package-context) t
+        (etypecase package
+          (null nil)
+          ((eql (find-package :cl)) :cl)
+          (package (package-name package)))))
+  (defun unreify-package (package &optional package-context)
+    (etypecase package
+      (null nil)
+      ((eql t) package-context)
+      ((or symbol string) (find-package package))))
+  (defun reify-symbol (symbol &optional package-context)
+    (etypecase symbol
+      ((or keyword (satisfies standard-common-lisp-symbol-p)) symbol)
+      (symbol (vector (symbol-name symbol)
+                      (reify-package (symbol-package symbol) package-context)))))
+  (defun unreify-symbol (symbol &optional package-context)
+    (etypecase symbol
+      (symbol symbol)
+      ((simple-vector 2)
+       (let* ((symbol-name (svref symbol 0))
+              (package-foo (svref symbol 1))
+              (package (unreify-package package-foo package-context)))
+         (if package (intern* symbol-name package)
+             (make-symbol* symbol-name)))))))
+
+(eval-when (:load-toplevel :compile-toplevel :execute)
+  (defvar *all-package-happiness* '())
+  (defvar *all-package-fishiness* (list t))
+  (defun record-fishy (info)
+    ;;(format t "~&FISHY: ~S~%" info)
+    (push info *all-package-fishiness*))
+  (defmacro when-package-fishiness (&body body)
+    `(when *all-package-fishiness* ,@body))
+  (defmacro note-package-fishiness (&rest info)
+    `(when-package-fishiness (record-fishy (list ,@info)))))
+
+(eval-when (:load-toplevel :compile-toplevel :execute)
+  #+(or clisp clozure)
+  (defun get-setf-function-symbol (symbol)
+    #+clisp (let ((sym (get symbol 'system::setf-function)))
+              (if sym (values sym :setf-function)
+                  (let ((sym (get symbol 'system::setf-expander)))
+                    (if sym (values sym :setf-expander)
+                        (values nil nil)))))
+    #+clozure (gethash symbol ccl::%setf-function-names%))
+  #+(or clisp clozure)
+  (defun set-setf-function-symbol (new-setf-symbol symbol &optional kind)
+    #+clisp (assert (member kind '(:setf-function :setf-expander)))
+    #+clozure (assert (eq kind t))
+    #+clisp
+    (cond
+      ((null new-setf-symbol)
+       (remprop symbol 'system::setf-function)
+       (remprop symbol 'system::setf-expander))
+      ((eq kind :setf-function)
+       (setf (get symbol 'system::setf-function) new-setf-symbol))
+      ((eq kind :setf-expander)
+       (setf (get symbol 'system::setf-expander) new-setf-symbol))
+      (t (error "invalid kind of setf-function ~S for ~S to be set to ~S"
+                kind symbol new-setf-symbol)))
+    #+clozure
+    (progn
+      (gethash symbol ccl::%setf-function-names%) new-setf-symbol
+      (gethash new-setf-symbol ccl::%setf-function-name-inverses%) symbol))
+  #+(or clisp clozure)
+  (defun create-setf-function-symbol (symbol)
+    #+clisp (system::setf-symbol symbol)
+    #+clozure (ccl::construct-setf-function-name symbol))
+  (defun set-dummy-symbol (symbol reason other-symbol)
+    (setf (get symbol 'dummy-symbol) (cons reason other-symbol)))
+  (defun make-dummy-symbol (symbol)
+    (let ((dummy (copy-symbol symbol)))
+      (set-dummy-symbol dummy 'replacing symbol)
+      (set-dummy-symbol symbol 'replaced-by dummy)
+      dummy))
+  (defun dummy-symbol (symbol)
+    (get symbol 'dummy-symbol))
+  (defun get-dummy-symbol (symbol)
+    (let ((existing (dummy-symbol symbol)))
+      (if existing (values (cdr existing) (car existing))
+          (make-dummy-symbol symbol))))
+  (defun nuke-symbol-in-package (symbol package-designator)
+    (let ((package (find-package* package-designator))
+          (name (symbol-name symbol)))
+      (multiple-value-bind (sym stat) (find-symbol name package)
+        (when (and (member stat '(:internal :external)) (eq symbol sym))
+          (if (symbol-shadowing-p symbol package)
+              (shadowing-import* (get-dummy-symbol symbol) package)
+              (unintern* symbol package))))))
+  (defun nuke-symbol (symbol &optional (packages (list-all-packages)))
+    #+(or clisp clozure)
+    (multiple-value-bind (setf-symbol kind)
+        (get-setf-function-symbol symbol)
+      (when kind (nuke-symbol setf-symbol)))
+    (loop :for p :in packages :do (nuke-symbol-in-package symbol p)))
+  (defun rehome-symbol (symbol package-designator)
+    "Changes the home package of a symbol, also leaving it present in its old home if any"
+    (let* ((name (symbol-name symbol))
+           (package (find-package* package-designator))
+           (old-package (symbol-package symbol))
+           (old-status (and old-package (nth-value 1 (find-symbol name old-package))))
+           (shadowing (and old-package (symbol-shadowing-p symbol old-package) (make-symbol name))))
+      (multiple-value-bind (overwritten-symbol overwritten-symbol-status) (find-symbol name package)
+        (unless (eq package old-package)
+          (let ((overwritten-symbol-shadowing-p
+                  (and overwritten-symbol-status
+                       (symbol-shadowing-p overwritten-symbol package))))
+            (note-package-fishiness
+             :rehome-symbol name
+             (when old-package (package-name old-package)) old-status (and shadowing t)
+             (package-name package) overwritten-symbol-status overwritten-symbol-shadowing-p)
+            (when old-package
+              (if shadowing
+                  (shadowing-import* shadowing old-package))
+              (unintern* symbol old-package))
+            (cond
+              (overwritten-symbol-shadowing-p
+               (shadowing-import* symbol package))
+              (t
+               (when overwritten-symbol-status
+                 (unintern* overwritten-symbol package))
+               (import* symbol package)))
+            (if shadowing
+                (shadowing-import* symbol old-package)
+                (import* symbol old-package))
+            #+(or clisp clozure)
+            (multiple-value-bind (setf-symbol kind)
+                (get-setf-function-symbol symbol)
+              (when kind
+                (let* ((setf-function (fdefinition setf-symbol))
+                       (new-setf-symbol (create-setf-function-symbol symbol)))
+                  (note-package-fishiness
+                   :setf-function
+                   name (package-name package)
+                   (symbol-name setf-symbol) (symbol-package-name setf-symbol)
+                   (symbol-name new-setf-symbol) (symbol-package-name new-setf-symbol))
+                  (when (symbol-package setf-symbol)
+                    (unintern* setf-symbol (symbol-package setf-symbol)))
+                  (setf (fdefinition new-setf-symbol) setf-function)
+                  (set-setf-function-symbol new-setf-symbol symbol kind))))
+            #+(or clisp clozure)
+            (multiple-value-bind (overwritten-setf foundp)
+                (get-setf-function-symbol overwritten-symbol)
+              (when foundp
+                (unintern overwritten-setf)))
+            (when (eq old-status :external)
+              (export* symbol old-package))
+            (when (eq overwritten-symbol-status :external)
+              (export* symbol package))))
+        (values overwritten-symbol overwritten-symbol-status))))
+  (defun ensure-package-unused (package)
+    (loop :for p :in (package-used-by-list package) :do
+      (unuse-package package p)))
+  (defun delete-package* (package &key nuke)
+    (let ((p (find-package package)))
+      (when p
+        (when nuke (do-symbols (s p) (when (home-package-p s p) (nuke-symbol s))))
+        (ensure-package-unused p)
+        (delete-package package))))
+  (defun package-names (package)
+    (cons (package-name package) (package-nicknames package)))
+  (defun packages-from-names (names)
+    (remove-duplicates (remove nil (mapcar #'find-package names)) :from-end t))
+  (defun fresh-package-name (&key (prefix :%TO-BE-DELETED)
+                               separator
+                               (index (random most-positive-fixnum)))
+    (loop :for i :from index
+          :for n = (format nil "~A~@[~A~D~]" prefix (and (plusp i) (or separator "")) i)
+          :thereis (and (not (find-package n)) n)))
+  (defun rename-package-away (p &rest keys &key prefix &allow-other-keys)
+    (let ((new-name
+            (apply 'fresh-package-name
+                   :prefix (or prefix (format nil "__~A__" (package-name p))) keys)))
+      (record-fishy (list :rename-away (package-names p) new-name))
+      (rename-package p new-name))))
+
+
+;;; Communicable representation of symbol and package information
+
+(eval-when (:load-toplevel :compile-toplevel :execute)
+  (defun package-definition-form (package-designator
+                                  &key (nicknamesp t) (usep t)
+                                    (shadowp t) (shadowing-import-p t)
+                                    (exportp t) (importp t) internp (error t))
+    (let* ((package (or (find-package* package-designator error)
+                        (return-from package-definition-form nil)))
+           (name (package-name package))
+           (nicknames (package-nicknames package))
+           (use (mapcar #'package-name (package-use-list package)))
+           (shadow ())
+           (shadowing-import (make-hash-table :test 'equal))
+           (import (make-hash-table :test 'equal))
+           (export ())
+           (intern ()))
+      (when package
+        (loop :for sym :being :the :symbols :in package
+              :for status = (nth-value 1 (find-symbol* sym package)) :do
+                (ecase status
+                  ((nil :inherited))
+                  ((:internal :external)
+                   (let* ((name (symbol-name sym))
+                          (external (eq status :external))
+                          (home (symbol-package sym))
+                          (home-name (package-name home))
+                          (imported (not (eq home package)))
+                          (shadowing (symbol-shadowing-p sym package)))
+                     (cond
+                       ((and shadowing imported)
+                        (push name (gethash home-name shadowing-import)))
+                       (shadowing
+                        (push name shadow))
+                       (imported
+                        (push name (gethash home-name import))))
+                     (cond
+                       (external
+                        (push name export))
+                       (imported)
+                       (t (push name intern)))))))
+        (labels ((sort-names (names)
+                   (sort (copy-list names) #'string<))
+                 (table-keys (table)
+                   (loop :for k :being :the :hash-keys :of table :collect k))
+                 (when-relevant (key value)
+                   (when value (list (cons key value))))
+                 (import-options (key table)
+                   (loop :for i :in (sort-names (table-keys table))
+                         :collect `(,key ,i ,@(sort-names (gethash i table))))))
+          `(defpackage ,name
+             ,@(when-relevant :nicknames (and nicknamesp (sort-names nicknames)))
+             (:use ,@(and usep (sort-names use)))
+             ,@(when-relevant :shadow (and shadowp (sort-names shadow)))
+             ,@(import-options :shadowing-import-from (and shadowing-import-p shadowing-import))
+             ,@(import-options :import-from (and importp import))
+             ,@(when-relevant :export (and exportp (sort-names export)))
+             ,@(when-relevant :intern (and internp (sort-names intern)))))))))
+
+
+;;; ensure-package, define-package
+(eval-when (:load-toplevel :compile-toplevel :execute)
+  (defun ensure-shadowing-import (name to-package from-package shadowed imported)
+    (check-type name string)
+    (check-type to-package package)
+    (check-type from-package package)
+    (check-type shadowed hash-table)
+    (check-type imported hash-table)
+    (let ((import-me (find-symbol* name from-package)))
+      (multiple-value-bind (existing status) (find-symbol name to-package)
+        (cond
+          ((gethash name shadowed)
+           (unless (eq import-me existing)
+             (error "Conflicting shadowings for ~A" name)))
+          (t
+           (setf (gethash name shadowed) t)
+           (setf (gethash name imported) t)
+           (unless (or (null status)
+                       (and (member status '(:internal :external))
+                            (eq existing import-me)
+                            (symbol-shadowing-p existing to-package)))
+             (note-package-fishiness
+              :shadowing-import name
+              (package-name from-package)
+              (or (home-package-p import-me from-package) (symbol-package-name import-me))
+              (package-name to-package) status
+              (and status (or (home-package-p existing to-package) (symbol-package-name existing)))))
+           (shadowing-import* import-me to-package))))))
+  (defun ensure-imported (import-me into-package &optional from-package)
+    (check-type import-me symbol)
+    (check-type into-package package)
+    (check-type from-package (or null package))
+    (let ((name (symbol-name import-me)))
+      (multiple-value-bind (existing status) (find-symbol name into-package)
+        (cond
+          ((not status)
+           (import* import-me into-package))
+          ((eq import-me existing))
+          (t
+           (let ((shadowing-p (symbol-shadowing-p existing into-package)))
+             (note-package-fishiness
+              :ensure-imported name
+              (and from-package (package-name from-package))
+              (or (home-package-p import-me from-package) (symbol-package-name import-me))
+              (package-name into-package)
+              status
+              (and status (or (home-package-p existing into-package) (symbol-package-name existing)))
+              shadowing-p)
+             (cond
+               ((or shadowing-p (eq status :inherited))
+                (shadowing-import* import-me into-package))
+               (t
+                (unintern* existing into-package)
+                (import* import-me into-package))))))))
+    (values))
+  (defun ensure-import (name to-package from-package shadowed imported)
+    (check-type name string)
+    (check-type to-package package)
+    (check-type from-package package)
+    (check-type shadowed hash-table)
+    (check-type imported hash-table)
+    (multiple-value-bind (import-me import-status) (find-symbol name from-package)
+      (when (null import-status)
+        (note-package-fishiness
+         :import-uninterned name (package-name from-package) (package-name to-package))
+        (setf import-me (intern* name from-package)))
+      (multiple-value-bind (existing status) (find-symbol name to-package)
+        (cond
+          ((and imported (gethash name imported))
+           (unless (and status (eq import-me existing))
+             (error "Can't import ~S from both ~S and ~S"
+                    name (package-name (symbol-package existing)) (package-name from-package))))
+          ((gethash name shadowed)
+           (error "Can't both shadow ~S and import it from ~S" name (package-name from-package)))
+          (t
+           (setf (gethash name imported) t))))
+      (ensure-imported import-me to-package from-package)))
+  (defun ensure-inherited (name symbol to-package from-package mixp shadowed imported inherited)
+    (check-type name string)
+    (check-type symbol symbol)
+    (check-type to-package package)
+    (check-type from-package package)
+    (check-type mixp (member nil t)) ; no cl:boolean on Genera
+    (check-type shadowed hash-table)
+    (check-type imported hash-table)
+    (check-type inherited hash-table)
+    (multiple-value-bind (existing status) (find-symbol name to-package)
+      (let* ((sp (symbol-package symbol))
+             (in (gethash name inherited))
+             (xp (and status (symbol-package existing))))
+        (when (null sp)
+          (note-package-fishiness
+           :import-uninterned name
+           (package-name from-package) (package-name to-package) mixp)
+          (import* symbol from-package)
+          (setf sp (package-name from-package)))
+        (cond
+          ((gethash name shadowed))
+          (in
+           (unless (equal sp (first in))
+             (if mixp
+                 (ensure-shadowing-import name to-package (second in) shadowed imported)
+                 (error "Can't inherit ~S from ~S, it is inherited from ~S"
+                        name (package-name sp) (package-name (first in))))))
+          ((gethash name imported)
+           (unless (eq symbol existing)
+             (error "Can't inherit ~S from ~S, it is imported from ~S"
+                    name (package-name sp) (package-name xp))))
+          (t
+           (setf (gethash name inherited) (list sp from-package))
+           (when (and status (not (eq sp xp)))
+             (let ((shadowing (symbol-shadowing-p existing to-package)))
+               (note-package-fishiness
+                :inherited name
+                (package-name from-package)
+                (or (home-package-p symbol from-package) (symbol-package-name symbol))
+                (package-name to-package)
+                (or (home-package-p existing to-package) (symbol-package-name existing)))
+               (if shadowing (ensure-shadowing-import name to-package from-package shadowed imported)
+                   (unintern* existing to-package)))))))))
+  (defun ensure-mix (name symbol to-package from-package shadowed imported inherited)
+    (check-type name string)
+    (check-type symbol symbol)
+    (check-type to-package package)
+    (check-type from-package package)
+    (check-type shadowed hash-table)
+    (check-type imported hash-table)
+    (check-type inherited hash-table)
+    (unless (gethash name shadowed)
+      (multiple-value-bind (existing status) (find-symbol name to-package)
+        (let* ((sp (symbol-package symbol))
+               (im (gethash name imported))
+               (in (gethash name inherited)))
+          (cond
+            ((or (null status)
+                 (and status (eq symbol existing))
+                 (and in (eq sp (first in))))
+             (ensure-inherited name symbol to-package from-package t shadowed imported inherited))
+            (in
+             (remhash name inherited)
+             (ensure-shadowing-import name to-package (second in) shadowed imported))
+            (im
+             (error "Symbol ~S import from ~S~:[~; actually ~:[uninterned~;~:*from ~S~]~] conflicts with existing symbol in ~S~:[~; actually ~:[uninterned~;from ~:*~S~]~]"
+                    name (package-name from-package)
+                    (home-package-p symbol from-package) (symbol-package-name symbol)
+                    (package-name to-package)
+                    (home-package-p existing to-package) (symbol-package-name existing)))
+            (t
+             (ensure-inherited name symbol to-package from-package t shadowed imported inherited)))))))
+
+  (defun recycle-symbol (name recycle exported)
+    ;; Takes a symbol NAME (a string), a list of package designators for RECYCLE
+    ;; packages, and a hash-table of names (strings) of symbols scheduled to be
+    ;; EXPORTED from the package being defined. It returns two values, the
+    ;; symbol found (if any, or else NIL), and a boolean flag indicating whether
+    ;; a symbol was found. The caller (DEFINE-PACKAGE) will then do the
+    ;; re-homing of the symbol, etc.
+    (check-type name string)
+    (check-type recycle list)
+    (check-type exported hash-table)
+    (when (gethash name exported) ;; don't bother recycling private symbols
+      (let (recycled foundp)
+        (dolist (r recycle (values recycled foundp))
+          (multiple-value-bind (symbol status) (find-symbol name r)
+            (when (and status (home-package-p symbol r))
+              (cond
+                (foundp
+                 ;; (nuke-symbol symbol)) -- even simple variable names like O or C will do that.
+                 (note-package-fishiness :recycled-duplicate name (package-name foundp) (package-name r)))
+                (t
+                 (setf recycled symbol foundp r)))))))))
+  (defun symbol-recycled-p (sym recycle)
+    (check-type sym symbol)
+    (check-type recycle list)
+    (and (member (symbol-package sym) recycle) t))
+  (defun ensure-symbol (name package intern recycle shadowed imported inherited exported)
+    (check-type name string)
+    (check-type package package)
+    (check-type intern (member nil t)) ; no cl:boolean on Genera
+    (check-type shadowed hash-table)
+    (check-type imported hash-table)
+    (check-type inherited hash-table)
+    (unless (or (gethash name shadowed)
+                (gethash name imported)
+                (gethash name inherited))
+      (multiple-value-bind (existing status)
+          (find-symbol name package)
+        (multiple-value-bind (recycled previous) (recycle-symbol name recycle exported)
+          (cond
+            ((and status (eq existing recycled) (eq previous package)))
+            (previous
+             (rehome-symbol recycled package))
+            ((and status (eq package (symbol-package existing))))
+            (t
+             (when status
+               (note-package-fishiness
+                :ensure-symbol name
+                (reify-package (symbol-package existing) package)
+                status intern)
+               (unintern existing))
+             (when intern
+               (intern* name package))))))))
+  (declaim (ftype (function (t t t &optional t) t) ensure-exported))
+  (defun ensure-exported-to-user (name symbol to-package &optional recycle)
+    (check-type name string)
+    (check-type symbol symbol)
+    (check-type to-package package)
+    (check-type recycle list)
+    (assert (equal name (symbol-name symbol)))
+    (multiple-value-bind (existing status) (find-symbol name to-package)
+      (unless (and status (eq symbol existing))
+        (let ((accessible
+                (or (null status)
+                    (let ((shadowing (symbol-shadowing-p existing to-package))
+                          (recycled (symbol-recycled-p existing recycle)))
+                      (unless (and shadowing (not recycled))
+                        (note-package-fishiness
+                         :ensure-export name (symbol-package-name symbol)
+                         (package-name to-package)
+                         (or (home-package-p existing to-package) (symbol-package-name existing))
+                         status shadowing)
+                        (if (or (eq status :inherited) shadowing)
+                            (shadowing-import* symbol to-package)
+                            (unintern existing to-package))
+                        t)))))
+          (when (and accessible (eq status :external))
+            (ensure-exported name symbol to-package recycle))))))
+  (defun ensure-exported (name symbol from-package &optional recycle)
+    (dolist (to-package (package-used-by-list from-package))
+      (ensure-exported-to-user name symbol to-package recycle))
+    (unless (eq from-package (symbol-package symbol))
+      (ensure-imported symbol from-package))
+    (export* name from-package))
+  (defun ensure-export (name from-package &optional recycle)
+    (multiple-value-bind (symbol status) (find-symbol* name from-package)
+      (unless (eq status :external)
+        (ensure-exported name symbol from-package recycle))))
+
+  #+package-local-nicknames
+  (defun install-package-local-nicknames (destination-package new-nicknames)
+    ;; First, remove all package-local nicknames. (We'll reinstall any desired ones later.)
+    (dolist (pair-to-remove (uiop/package-local-nicknames:package-local-nicknames destination-package))
+      (uiop/package-local-nicknames:remove-package-local-nickname
+       (string (car pair-to-remove)) destination-package))
+    ;; Then, install all desired nicknames.
+    (loop :for (nickname package) :in new-nicknames
+          :do (uiop/package-local-nicknames:add-package-local-nickname
+               (string nickname)
+               (find-package package)
+               destination-package)))
+
+  (defun ensure-package (name &key
+                                nicknames documentation use
+                                shadow shadowing-import-from
+                                import-from export intern
+                                recycle mix reexport
+                                unintern local-nicknames)
+    #+genera (declare (ignore documentation))
+    (let* ((package-name (string name))
+           (nicknames (mapcar #'string nicknames))
+           (names (cons package-name nicknames))
+           (previous (packages-from-names names))
+           (discarded (cdr previous))
+           (to-delete ())
+           (package (or (first previous) (make-package package-name :nicknames nicknames)))
+           (recycle (packages-from-names recycle))
+           (use (mapcar 'find-package* use))
+           (mix (mapcar 'find-package* mix))
+           (reexport (mapcar 'find-package* reexport))
+           (shadow (mapcar 'string shadow))
+           (export (mapcar 'string export))
+           (intern (mapcar 'string intern))
+           (unintern (mapcar 'string unintern))
+           (local-nicknames (mapcar #'(lambda (pair) (mapcar 'string pair)) local-nicknames))
+           (shadowed (make-hash-table :test 'equal)) ; string to bool
+           (imported (make-hash-table :test 'equal)) ; string to bool
+           (exported (make-hash-table :test 'equal)) ; string to bool
+           ;; string to list home package and use package:
+           (inherited (make-hash-table :test 'equal)))
+      #-package-local-nicknames
+      (declare (ignore local-nicknames)) ; if not supported
+      (when-package-fishiness (record-fishy package-name))
+      ;; if supported, put package documentation
+      #-genera
+      (when documentation (setf (documentation package t) documentation))
+      ;; remove unwanted packages from use list
+      (loop :for p :in (set-difference (package-use-list package) (append mix use))
+            :do (note-package-fishiness :over-use name (package-names p))
+                (unuse-package p package))
+      ;; mark unwanted packages for deletion
+      (loop :for p :in discarded
+            :for n = (remove-if #'(lambda (x) (member x names :test 'equal))
+                                (package-names p))
+            :do (note-package-fishiness :nickname name (package-names p))
+                (cond (n (rename-package p (first n) (rest n)))
+                      (t (rename-package-away p)
+                         (push p to-delete))))
+      ;; give package its desired name
+      (rename-package package package-name nicknames)
+      ;; Handle local nicknames
+      #+package-local-nicknames
+      (install-package-local-nicknames package local-nicknames)
+      (dolist (name unintern)
+        (multiple-value-bind (existing status) (find-symbol name package)
+          (when status
+            (unless (eq status :inherited)
+              (note-package-fishiness
+               :unintern (package-name package) name (symbol-package-name existing) status)
+              (unintern* name package nil)))))
+      ;; handle exports
+      (dolist (name export)
+        (setf (gethash name exported) t))
+      ;; handle reexportss
+      (dolist (p reexport)
+        (do-external-symbols (sym p)
+          (setf (gethash (string sym) exported) t)))
+      ;; unexport symbols not listed in (re)export
+      (do-external-symbols (sym package)
+        (let ((name (symbol-name sym)))
+          (unless (gethash name exported)
+            (note-package-fishiness
+             :over-export (package-name package) name
+             (or (home-package-p sym package) (symbol-package-name sym)))
+            (unexport sym package))))
+      ;; handle explicitly listed shadowed ssymbols
+      (dolist (name shadow)
+        (setf (gethash name shadowed) t)
+        (multiple-value-bind (existing status) (find-symbol name package)
+          (multiple-value-bind (recycled previous) (recycle-symbol name recycle exported)
+            (let ((shadowing (and status (symbol-shadowing-p existing package))))
+              (cond
+                ((eq previous package))
+                (previous
+                 (rehome-symbol recycled package))
+                ((or (member status '(nil :inherited))
+                     (home-package-p existing package)))
+                (t
+                 (let ((dummy (make-symbol name)))
+                   (note-package-fishiness
+                    :shadow-imported (package-name package) name
+                    (symbol-package-name existing) status shadowing)
+                   (shadowing-import* dummy package)
+                   (import* dummy package)))))))
+        (shadow* name package))
+      ;; handle shadowing imports
+      (loop :for (p . syms) :in shadowing-import-from
+            :for pp = (find-package* p) :do
+              (dolist (sym syms) (ensure-shadowing-import (string sym) package pp shadowed imported)))
+      ;; handle mixed packages
+      (loop :for p :in mix
+            :for pp = (find-package* p) :do
+              (do-external-symbols (sym pp) (ensure-mix (symbol-name sym) sym package pp shadowed imported inherited)))
+      ;; handle import-from packages
+      (loop :for (p . syms) :in import-from
+            :for pp = (find-package p) :do
+              (dolist (sym syms) (ensure-import (symbol-name sym) package pp shadowed imported)))
+      ;; handle use-list and mix
+      (dolist (p (append use mix))
+        (do-external-symbols (sym p) (ensure-inherited (string sym) sym package p nil shadowed imported inherited))
+        (use-package p package))
+      (loop :for name :being :the :hash-keys :of exported :do
+        (ensure-symbol name package t recycle shadowed imported inherited exported)
+        (ensure-export name package recycle))
+      ;; intern dessired symbols
+      (dolist (name intern)
+        (ensure-symbol name package t recycle shadowed imported inherited exported))
+      (do-symbols (sym package)
+        (ensure-symbol (symbol-name sym) package nil recycle shadowed imported inherited exported))
+      ;; delete now-deceased packages
+      (map () 'delete-package* to-delete)
+      package)))
+
+
+(eval-when (:load-toplevel :compile-toplevel :execute)
+  (defun parse-define-package-form (package clauses)
+    (loop
+      :with use-p = nil :with recycle-p = nil
+      :with documentation = nil
+      :for (kw . args) :in clauses
+      :when (eq kw :nicknames) :append args :into nicknames :else
+      :when (eq kw :documentation)
+        :do (cond
+              (documentation (error "define-package: can't define documentation twice"))
+              ((or (atom args) (cdr args)) (error "define-package: bad documentation"))
+              (t (setf documentation (car args)))) :else
+      :when (eq kw :use) :append args :into use :and :do (setf use-p t) :else
+      :when (eq kw :shadow) :append args :into shadow :else
+      :when (eq kw :shadowing-import-from) :collect args :into shadowing-import-from :else
+      :when (eq kw :import-from) :collect args :into import-from :else
+      :when (eq kw :export) :append args :into export :else
+      :when (eq kw :intern) :append args :into intern :else
+      :when (eq kw :recycle) :append args :into recycle :and :do (setf recycle-p t) :else
+      :when (eq kw :mix) :append args :into mix :else
+      :when (eq kw :reexport) :append args :into reexport :else
+      :when (eq kw :use-reexport) :append args :into use :and :append args :into reexport
+        :and :do (setf use-p t) :else
+      :when (eq kw :mix-reexport) :append args :into mix :and :append args :into reexport
+        :and :do (setf use-p t) :else
+      :when (eq kw :unintern) :append args :into unintern :else
+      :when (eq kw :local-nicknames)
+        :if (symbol-call '#:uiop '#:featurep :package-local-nicknames)
+          :append args :into local-nicknames
+        :else
+          :do (error ":LOCAL-NICKAMES option is not supported on this lisp implementation.")
+        :end
+      :else
+        :do (error "unrecognized define-package keyword ~S" kw)
+      :finally (return `(',package
+                         :nicknames ',nicknames :documentation ',documentation
+                         :use ',(if use-p use '(:common-lisp))
+                         :shadow ',shadow :shadowing-import-from ',shadowing-import-from
+                         :import-from ',import-from :export ',export :intern ',intern
+                         :recycle ',(if recycle-p recycle (cons package nicknames))
+                         :mix ',mix :reexport ',reexport :unintern ',unintern
+                         :local-nicknames ',local-nicknames)))))
+
+(defmacro define-package (package &rest clauses)
+  "DEFINE-PACKAGE takes a PACKAGE and a number of CLAUSES, of the form
+\(KEYWORD . ARGS\).
+DEFINE-PACKAGE supports the following keywords:
+USE, SHADOW, SHADOWING-IMPORT-FROM, IMPORT-FROM, EXPORT, INTERN, NICKNAMES,
+DOCUMENTATION -- as per CL:DEFPACKAGE.
+RECYCLE -- Recycle the package's exported symbols from the specified packages,
+in order.  For every symbol scheduled to be exported by the DEFINE-PACKAGE,
+either through an :EXPORT option or a :REEXPORT option, if the symbol exists in
+one of the :RECYCLE packages, the first such symbol is re-homed to the package
+being defined.
+For the sake of idempotence, it is important that the package being defined
+should appear in first position if it already exists, and even if it doesn't,
+ahead of any package that is not going to be deleted afterwards and never
+created again. In short, except for special cases, always make it the first
+package on the list if the list is not empty.
+MIX -- Takes a list of package designators.  MIX behaves like
+\(:USE PKG1 PKG2 ... PKGn\) but additionally uses :SHADOWING-IMPORT-FROM to
+resolve conflicts in favor of the first found symbol.  It may still yield
+an error if there is a conflict with an explicitly :IMPORT-FROM symbol.
+REEXPORT -- Takes a list of package designators.  For each package, p, in the list,
+export symbols with the same name as those exported from p.  Note that in the case
+of shadowing, etc. the symbols with the same name may not be the same symbols.
+UNINTERN -- Remove symbols here from PACKAGE.
+LOCAL-NICKNAMES -- If the host implementation supports package local nicknames
+\(check for the :PACKAGE-LOCAL-NICKNAMES feature\), then this should be a list of
+nickname and package name pairs.  Using this option will cause an error if the
+host CL implementation does not support it.
+USE-REEXPORT, MIX-REEXPORT -- Use or mix the specified packages as per the USE or
+MIX directives, and reexport their contents as per the REEXPORT directive."
+  (let ((ensure-form
+         `(prog1
+              (funcall 'ensure-package ,@(parse-define-package-form package clauses))
+            #+sbcl (setf (sb-impl::package-source-location (find-package ',package))
+                         (sb-c:source-location)))))
+    `(progn
+       #+(or clasp ecl gcl mkcl) (defpackage ,package (:use))
+       (eval-when (:compile-toplevel :load-toplevel :execute)
+         ,ensure-form))))
+
+;; This package, unlike UIOP/PACKAGE, is allowed to evolve and acquire new symbols or drop old ones.
+(define-package :uiop/package*
+  (:use-reexport :uiop/package
+                 #+package-local-nicknames :uiop/package-local-nicknames))
+;;;; -------------------------------------------------------------------------
+;;;; Handle compatibility with multiple implementations.
+;;; This file is for papering over the deficiencies and peculiarities
+;;; of various Common Lisp implementations.
+;;; For implementation-specific access to the system, see os.lisp instead.
+;;; A few functions are defined here, but actually exported from utility;
+;;; from this package only common-lisp symbols are exported.
+
+(uiop/package:define-package :uiop/common-lisp
+  (:nicknames :uiop/cl)
+  (:use :uiop/package)
+  (:use-reexport #-genera :common-lisp #+genera :future-common-lisp)
+  #+allegro (:intern #:*acl-warn-save*)
+  #+cormanlisp (:shadow #:user-homedir-pathname)
+  #+cormanlisp
+  (:export
+   #:logical-pathname #:translate-logical-pathname
+   #:make-broadcast-stream #:file-namestring)
+  #+genera (:shadowing-import-from :scl #:boolean)
+  #+genera (:export #:boolean #:ensure-directories-exist #:read-sequence #:write-sequence)
+  #+(or mcl cmucl) (:shadow #:user-homedir-pathname))
+(in-package :uiop/common-lisp)
+
+#-(or abcl allegro clasp clisp clozure cmucl cormanlisp ecl gcl genera lispworks mcl mezzano mkcl sbcl scl xcl)
+(error "ASDF is not supported on your implementation. Please help us port it.")
+
+;; (declaim (optimize (speed 1) (debug 3) (safety 3))) ; DON'T: trust implementation defaults.
+
+
+;;;; Early meta-level tweaks
+
+#+(or allegro clasp clisp clozure cmucl ecl lispworks mezzano mkcl sbcl)
+(eval-when (:load-toplevel :compile-toplevel :execute)
+  (when (and #+allegro (member :ics *features*)
+             #+(or clasp clisp cmucl ecl lispworks mkcl) (member :unicode *features*)
+             #+clozure (member :openmcl-unicode-strings *features*)
+             #+sbcl (member :sb-unicode *features*))
+    ;; Check for unicode at runtime, so that a hypothetical FASL compiled with unicode
+    ;; but loaded in a non-unicode setting (e.g. on Allegro) won't tell a lie.
+    (pushnew :asdf-unicode *features*)))
+
+#+allegro
+(eval-when (:load-toplevel :compile-toplevel :execute)
+  ;; We need to disable autoloading BEFORE any mention of package ASDF.
+  ;; In particular, there must NOT be a mention of package ASDF in the defpackage of this file
+  ;; or any previous file.
+  (setf excl::*autoload-package-name-alist*
+        (remove "asdf" excl::*autoload-package-name-alist*
+                :test 'equalp :key 'car))
+  (defparameter *acl-warn-save*
+    (when (boundp 'excl:*warn-on-nested-reader-conditionals*)
+      excl:*warn-on-nested-reader-conditionals*))
+  (when (boundp 'excl:*warn-on-nested-reader-conditionals*)
+    (setf excl:*warn-on-nested-reader-conditionals* nil))
+  (setf *print-readably* nil))
+
+#+clasp
+(eval-when (:load-toplevel :compile-toplevel :execute)
+  (setf *load-verbose* nil)
+  (defun use-ecl-byte-compiler-p () nil))
+
+#+clozure (in-package :ccl)
+#+(and clozure windows-target) ;; See http://trac.clozure.com/ccl/ticket/1117
+(eval-when (:load-toplevel :compile-toplevel :execute)
+  (unless (fboundp 'external-process-wait)
+    (in-development-mode
+     (defun external-process-wait (proc)
+       (when (and (external-process-pid proc) (eq (external-process-%status proc) :running))
+         (with-interrupts-enabled
+             (wait-on-semaphore (external-process-completed proc))))
+       (values (external-process-%exit-code proc)
+               (external-process-%status proc))))))
+#+clozure (in-package :uiop/common-lisp) ;; back in this package.
+
+#+cmucl
+(eval-when (:load-toplevel :compile-toplevel :execute)
+  (setf ext:*gc-verbose* nil)
+  (defun user-homedir-pathname ()
+    (first (ext:search-list (cl:user-homedir-pathname)))))
+
+#+cormanlisp
+(eval-when (:load-toplevel :compile-toplevel :execute)
+  (deftype logical-pathname () nil)
+  (defun make-broadcast-stream () *error-output*)
+  (defun translate-logical-pathname (x) x)
+  (defun user-homedir-pathname (&optional host)
+    (declare (ignore host))
+    (parse-namestring (format nil "~A\\" (cl:user-homedir-pathname))))
+  (defun file-namestring (p)
+    (setf p (pathname p))
+    (format nil "~@[~A~]~@[.~A~]" (pathname-name p) (pathname-type p))))
+
+#+ecl
+(eval-when (:load-toplevel :compile-toplevel :execute)
+  (setf *load-verbose* nil)
+  (defun use-ecl-byte-compiler-p () (and (member :ecl-bytecmp *features*) t))
+  (unless (use-ecl-byte-compiler-p) (require :cmp)))
+
+#+gcl
+(eval-when (:load-toplevel :compile-toplevel :execute)
+  (unless (member :ansi-cl *features*)
+    (error "ASDF only supports GCL in ANSI mode. Aborting.~%"))
+  (setf compiler::*compiler-default-type* (pathname "")
+        compiler::*lsp-ext* "")
+  #.(let ((code ;; Only support very recent GCL 2.7.0 from November 2013 or later.
+            (cond
+              #+gcl
+              ((or (< system::*gcl-major-version* 2)
+                   (and (= system::*gcl-major-version* 2)
+                        (< system::*gcl-minor-version* 7)))
+               '(error "GCL 2.7 or later required to use ASDF")))))
+      (eval code)
+      code))
+
+#+genera
+(eval-when (:load-toplevel :compile-toplevel :execute)
+  (unless (fboundp 'lambda)
+    (defmacro lambda (&whole form &rest bvl-decls-and-body)
+      (declare (ignore bvl-decls-and-body)(zwei::indentation 1 1))
+      `#',(cons 'lisp::lambda (cdr form))))
+  (unless (fboundp 'ensure-directories-exist)
+    (defun ensure-directories-exist (path)
+      (fs:create-directories-recursively (pathname path))))
+  (unless (fboundp 'read-sequence)
+    (defun read-sequence (sequence stream &key (start 0) end)
+      (scl:send stream :string-in nil sequence start end)))
+  (unless (fboundp 'write-sequence)
+    (defun write-sequence (sequence stream &key (start 0) end)
+      (scl:send stream :string-out sequence start end)
+      sequence)))
+
+#+lispworks
+(eval-when (:load-toplevel :compile-toplevel :execute)
+  ;; lispworks 3 and earlier cannot be checked for so we always assume
+  ;; at least version 4
+  (unless (member :lispworks4 *features*)
+    (pushnew :lispworks5+ *features*)
+    (unless (member :lispworks5 *features*)
+      (pushnew :lispworks6+ *features*)
+      (unless (member :lispworks6 *features*)
+        (pushnew :lispworks7+ *features*)))))
+
+
+#.(or #+mcl ;; the #$ doesn't work on other lisps, even protected by #+mcl, so we use this trick
+      (read-from-string
+       "(eval-when (:load-toplevel :compile-toplevel :execute)
+          (ccl:define-entry-point (_getenv \"getenv\") ((name :string)) :string)
+          (ccl:define-entry-point (_system \"system\") ((name :string)) :int)
+          ;; Note: ASDF may expect user-homedir-pathname to provide
+          ;; the pathname of the current user's home directory, whereas
+          ;; MCL by default provides the directory from which MCL was started.
+          ;; See http://code.google.com/p/mcl/wiki/Portability
+          (defun user-homedir-pathname ()
+            (ccl::findfolder #$kuserdomain #$kCurrentUserFolderType))
+          (defun probe-posix (posix-namestring)
+            \"If a file exists for the posix namestring, return the pathname\"
+            (ccl::with-cstrs ((cpath posix-namestring))
+              (ccl::rlet ((is-dir :boolean)
+                          (fsref :fsref))
+                (when (eq #$noerr (#_fspathmakeref cpath fsref is-dir))
+                  (ccl::%path-from-fsref fsref is-dir))))))"))
+
+#+mkcl
+(eval-when (:load-toplevel :compile-toplevel :execute)
+  (require :cmp)
+  (setq clos::*redefine-class-in-place* t)) ;; Make sure we have strict ANSI class redefinition semantics
+
+
+;;;; compatfmt: avoid fancy format directives when unsupported
+(eval-when (:load-toplevel :compile-toplevel :execute)
+  (defun frob-substrings (string substrings &optional frob)
+    "for each substring in SUBSTRINGS, find occurrences of it within STRING
+that don't use parts of matched occurrences of previous strings, and
+FROB them, that is to say, remove them if FROB is NIL,
+replace by FROB if FROB is a STRING, or if FROB is a FUNCTION,
+call FROB with the match and a function that emits a string in the output.
+Return a string made of the parts not omitted or emitted by FROB."
+    (declare (optimize (speed 0) (safety #-gcl 3 #+gcl 0) (debug 3)))
+    (let ((length (length string)) (stream nil))
+      (labels ((emit-string (x &optional (start 0) (end (length x)))
+                 (when (< start end)
+                   (unless stream (setf stream (make-string-output-stream)))
+                   (write-string x stream :start start :end end)))
+               (emit-substring (start end)
+                 (when (and (zerop start) (= end length))
+                   (return-from frob-substrings string))
+                 (emit-string string start end))
+               (recurse (substrings start end)
+                 (cond
+                   ((>= start end))
+                   ((null substrings) (emit-substring start end))
+                   (t (let* ((sub-spec (first substrings))
+                             (sub (if (consp sub-spec) (car sub-spec) sub-spec))
+                             (fun (if (consp sub-spec) (cdr sub-spec) frob))
+                             (found (search sub string :start2 start :end2 end))
+                             (more (rest substrings)))
+                        (cond
+                          (found
+                           (recurse more start found)
+                           (etypecase fun
+                             (null)
+                             (string (emit-string fun))
+                             (function (funcall fun sub #'emit-string)))
+                           (recurse substrings (+ found (length sub)) end))
+                          (t
+                           (recurse more start end))))))))
+        (recurse substrings 0 length))
+      (if stream (get-output-stream-string stream) "")))
+
+  (defmacro compatfmt (format)
+    #+(or gcl genera)
+    (frob-substrings format `("~3i~_" #+genera ,@'("~@<" "~@;" "~@:>" "~:>")))
+    #-(or gcl genera) format))
+;;;; -------------------------------------------------------------------------
+;;;; General Purpose Utilities for ASDF
+
+(uiop/package:define-package :uiop/utility
+  (:use :uiop/common-lisp :uiop/package)
+  ;; import and reexport a few things defined in :uiop/common-lisp
+  (:import-from :uiop/common-lisp #:compatfmt #:frob-substrings
+   #+(or clasp ecl) #:use-ecl-byte-compiler-p #+mcl #:probe-posix)
+  (:export #:compatfmt #:frob-substrings #:compatfmt
+   #+(or clasp ecl) #:use-ecl-byte-compiler-p #+mcl #:probe-posix)
+  (:export
+   ;; magic helper to define debugging functions:
+   #:uiop-debug #:load-uiop-debug-utility #:*uiop-debug-utility*
+   #:with-upgradability ;; (un)defining functions in an upgrade-friendly way
+   #:nest #:if-let ;; basic flow control
+   #:parse-body ;; macro definition helper
+   #:while-collecting #:appendf #:length=n-p #:ensure-list ;; lists
+   #:remove-plist-keys #:remove-plist-key ;; plists
+   #:emptyp ;; sequences
+   #:+non-base-chars-exist-p+ ;; characters
+   #:+max-character-type-index+ #:character-type-index #:+character-types+
+   #:base-string-p #:strings-common-element-type #:reduce/strcat #:strcat ;; strings
+   #:first-char #:last-char #:split-string #:stripln #:+cr+ #:+lf+ #:+crlf+
+   #:string-prefix-p #:string-enclosed-p #:string-suffix-p
+   #:standard-case-symbol-name #:find-standard-case-symbol ;; symbols
+   #:coerce-class ;; CLOS
+   #:timestamp< #:timestamps< #:timestamp*< #:timestamp<= ;; timestamps
+   #:earlier-timestamp #:timestamps-earliest #:earliest-timestamp
+   #:later-timestamp #:timestamps-latest #:latest-timestamp #:latest-timestamp-f
+   #:list-to-hash-set #:ensure-gethash ;; hash-table
+   #:ensure-function #:access-at #:access-at-count ;; functions
+   #:call-function #:call-functions #:register-hook-function
+   #:lexicographic< #:lexicographic<= ;; version
+   #:simple-style-warning #:style-warn ;; simple style warnings
+   #:match-condition-p #:match-any-condition-p ;; conditions
+   #:call-with-muffled-conditions #:with-muffled-conditions
+   #:not-implemented-error #:parameter-error
+   #:symbol-test-to-feature-expression
+   #:boolean-to-feature-expression))
+(in-package :uiop/utility)
+
+;;;; Defining functions in a way compatible with hot-upgrade:
+;; - The WTIH-UPGRADABILITY infrastructure below ensures that functions are declared NOTINLINE,
+;;   so that new definitions are always seen by all callers, even those up the stack.
+;; - WITH-UPGRADABILITY also uses EVAL-WHEN so that definitions used by ASDF are in a limbo state
+;;   (especially for gf's) in between the COMPILE-OP and LOAD-OP operations on the defining file.
+;; - THOU SHALT NOT redefine a function with a backward-incompatible semantics without renaming it,
+;;   at least if that function is used by ASDF while performing the plan to load ASDF.
+;; - THOU SHALT change the name of a function whenever thou makest an incompatible change.
+;; - For instance, when the meanings of NIL and T for timestamps was inverted,
+;;   functions in the STAMP<, STAMP<=, etc. family had to be renamed to TIMESTAMP<, TIMESTAMP<=, etc.,
+;;   because the change other caused a huge incompatibility during upgrade.
+;; - Whenever a function goes from a DEFUN to a DEFGENERIC, or the DEFGENERIC signature changes, etc.,
+;;   even in a backward-compatible way, you MUST precede the definition by FMAKUNBOUND.
+;; - Since FMAKUNBOUND will remove all the methods on the generic function, make sure that
+;;   all the methods required for ASDF to successfully continue compiling itself
+;;   shall be defined in the same file as the one with the FMAKUNBOUND, *after* the DEFGENERIC.
+;; - When a function goes from DEFGENERIC to DEFUN, you may omit to use FMAKUNBOUND.
+;; - For safety, you shall put the FMAKUNBOUND just before the DEFUN or DEFGENERIC,
+;;   in the same WITH-UPGRADABILITY form (and its implicit EVAL-WHEN).
+;; - Any time you change a signature, please keep a comment specifying the first release after the change;
+;;   put that comment on the same line as FMAKUNBOUND, it you use FMAKUNBOUND.
+(eval-when (:load-toplevel :compile-toplevel :execute)
+  (defun ensure-function-notinline (definition &aux (name (second definition)))
+    (assert (member (first definition) '(defun defgeneric)))
+    `(progn
+       ,(when (and #+(or clasp ecl) (symbolp name)) ; NB: fails for (SETF functions) on ECL
+          `(declaim (notinline ,name)))
+       ,definition))
+  (defmacro with-upgradability ((&optional) &body body)
+    "Evaluate BODY at compile- load- and run- times, with DEFUN and DEFGENERIC modified
+to also declare the functions NOTINLINE and to accept a wrapping the function name
+specification into a list with keyword argument SUPERSEDE (which defaults to T if the name
+is not wrapped, and NIL if it is wrapped). If SUPERSEDE is true, call UNDEFINE-FUNCTION
+to supersede any previous definition."
+    `(eval-when (:compile-toplevel :load-toplevel :execute)
+       ,@(loop :for form :in body :collect
+               (if (consp form)
+                   (case (first form)
+                     ((defun defgeneric) (ensure-function-notinline form))
+                     (otherwise form))
+                   form)))))
+
+;;; Magic debugging help. See contrib/debug.lisp
+(with-upgradability ()
+  (defvar *uiop-debug-utility*
+    '(symbol-call :uiop :subpathname (symbol-call :uiop :uiop-directory) "contrib/debug.lisp")
+    "form that evaluates to the pathname to your favorite debugging utilities")
+
+  (defmacro uiop-debug (&rest keys)
+    "Load the UIOP debug utility at compile-time as well as runtime"
+    `(eval-when (:compile-toplevel :load-toplevel :execute)
+       (load-uiop-debug-utility ,@keys)))
+
+  (defun load-uiop-debug-utility (&key package utility-file)
+    "Load the UIOP debug utility in given PACKAGE (default *PACKAGE*).
+Beware: The utility is located by EVAL'uating the UTILITY-FILE form (default *UIOP-DEBUG-UTILITY*)."
+    (let* ((*package* (if package (find-package package) *package*))
+           (keyword (read-from-string
+                     (format nil ":DBG-~:@(~A~)" (package-name *package*)))))
+      (unless (member keyword *features*)
+        (let* ((utility-file (or utility-file *uiop-debug-utility*))
+               (file (ignore-errors (probe-file (eval utility-file)))))
+          (if file (load file)
+              (error "Failed to locate debug utility file: ~S" utility-file)))))))
+
+;;; Flow control
+(with-upgradability ()
+  (defmacro nest (&rest things)
+    "Macro to keep code nesting and indentation under control." ;; Thanks to mbaringer
+    (reduce #'(lambda (outer inner) `(,@outer ,inner))
+            things :from-end t))
+
+  (defmacro if-let (bindings &body (then-form &optional else-form)) ;; from alexandria
+    ;; bindings can be (var form) or ((var1 form1) ...)
+    (let* ((binding-list (if (and (consp bindings) (symbolp (car bindings)))
+                             (list bindings)
+                             bindings))
+           (variables (mapcar #'car binding-list)))
+      `(let ,binding-list
+         (if (and ,@variables)
+             ,then-form
+             ,else-form)))))
+
+;;; Macro definition helper
+(with-upgradability ()
+  (defun parse-body (body &key documentation whole) ;; from alexandria
+    "Parses BODY into (values remaining-forms declarations doc-string).
+Documentation strings are recognized only if DOCUMENTATION is true.
+Syntax errors in body are signalled and WHOLE is used in the signal
+arguments when given."
+    (let ((doc nil)
+          (decls nil)
+          (current nil))
+      (tagbody
+       :declarations
+         (setf current (car body))
+         (when (and documentation (stringp current) (cdr body))
+           (if doc
+               (error "Too many documentation strings in ~S." (or whole body))
+               (setf doc (pop body)))
+           (go :declarations))
+         (when (and (listp current) (eql (first current) 'declare))
+           (push (pop body) decls)
+           (go :declarations)))
+      (values body (nreverse decls) doc))))
+
+
+;;; List manipulation
+(with-upgradability ()
+  (defmacro while-collecting ((&rest collectors) &body body)
+    "COLLECTORS should be a list of names for collections.  A collector
+defines a function that, when applied to an argument inside BODY, will
+add its argument to the corresponding collection.  Returns multiple values,
+a list for each collection, in order.
+   E.g.,
+\(while-collecting \(foo bar\)
+           \(dolist \(x '\(\(a 1\) \(b 2\) \(c 3\)\)\)
+             \(foo \(first x\)\)
+             \(bar \(second x\)\)\)\)
+Returns two values: \(A B C\) and \(1 2 3\)."
+    (let ((vars (mapcar #'(lambda (x) (gensym (symbol-name x))) collectors))
+          (initial-values (mapcar (constantly nil) collectors)))
+      `(let ,(mapcar #'list vars initial-values)
+         (flet ,(mapcar #'(lambda (c v) `(,c (x) (push x ,v) (values))) collectors vars)
+           ,@body
+           (values ,@(mapcar #'(lambda (v) `(reverse ,v)) vars))))))
+
+  (define-modify-macro appendf (&rest args)
+    append "Append onto list") ;; only to be used on short lists.
+
+  (defun length=n-p (x n) ;is it that (= (length x) n) ?
+    (check-type n (integer 0 *))
+    (loop
+      :for l = x :then (cdr l)
+      :for i :downfrom n :do
+        (cond
+          ((zerop i) (return (null l)))
+          ((not (consp l)) (return nil)))))
+
+  (defun ensure-list (x)
+    (if (listp x) x (list x))))
+
+
+;;; Remove a key from a plist, i.e. for keyword argument cleanup
+(with-upgradability ()
+  (defun remove-plist-key (key plist)
+    "Remove a single key from a plist"
+    (loop :for (k v) :on plist :by #'cddr
+          :unless (eq k key)
+            :append (list k v)))
+
+  (defun remove-plist-keys (keys plist)
+    "Remove a list of keys from a plist"
+    (loop :for (k v) :on plist :by #'cddr
+          :unless (member k keys)
+            :append (list k v))))
+
+
+;;; Sequences
+(with-upgradability ()
+  (defun emptyp (x)
+    "Predicate that is true for an empty sequence"
+    (or (null x) (and (vectorp x) (zerop (length x))))))
+
+
+;;; Characters
+(with-upgradability ()
+  ;; base-char != character on ECL, LW, SBCL, Genera.
+  ;; NB: We assume a total order on character types.
+  ;; If that's not true... this code will need to be updated.
+  (defparameter +character-types+ ;; assuming a simple hierarchy
+    #.(coerce (loop :for (type next) :on
+                    '(;; In SCL, all characters seem to be 16-bit base-char
+                      ;; Yet somehow character fails to be a subtype of base-char
+                      #-scl base-char
+                      ;; LW6 has BASE-CHAR < SIMPLE-CHAR < CHARACTER
+                      ;; LW7 has BASE-CHAR < BMP-CHAR < SIMPLE-CHAR = CHARACTER
+                      #+lispworks7+ lw:bmp-char
+                      #+lispworks lw:simple-char
+                      character)
+                    :unless (and next (subtypep next type))
+                      :collect type) 'vector))
+  (defparameter +max-character-type-index+ (1- (length +character-types+)))
+  (defconstant +non-base-chars-exist-p+ (plusp +max-character-type-index+))
+  (when +non-base-chars-exist-p+ (pushnew :non-base-chars-exist-p *features*)))
+
+(with-upgradability ()
+  (defun character-type-index (x)
+    (declare (ignorable x))
+    #.(case +max-character-type-index+
+        (0 0)
+        (1 '(etypecase x
+             (character (if (typep x 'base-char) 0 1))
+             (symbol (if (subtypep x 'base-char) 0 1))))
+        (otherwise
+         '(or (position-if (etypecase x
+                             (character #'(lambda (type) (typep x type)))
+                             (symbol #'(lambda (type) (subtypep x type))))
+               +character-types+)
+           (error "Not a character or character type: ~S" x))))))
+
+
+;;; Strings
+(with-upgradability ()
+  (defun base-string-p (string)
+    "Does the STRING only contain BASE-CHARs?"
+    (declare (ignorable string))
+    (and #+non-base-chars-exist-p (eq 'base-char (array-element-type string))))
+
+  (defun strings-common-element-type (strings)
+    "What least subtype of CHARACTER can contain all the elements of all the STRINGS?"
+    (declare (ignorable strings))
+    #.(if +non-base-chars-exist-p+
+          `(aref +character-types+
+            (loop :with index = 0 :for s :in strings :do
+              (flet ((consider (i)
+                       (cond ((= i ,+max-character-type-index+) (return i))
+                             ,@(when (> +max-character-type-index+ 1) `(((> i index) (setf index i)))))))
+                (cond
+                  ((emptyp s)) ;; NIL or empty string
+                  ((characterp s) (consider (character-type-index s)))
+                  ((stringp s) (let ((string-type-index
+                                       (character-type-index (array-element-type s))))
+                                 (unless (>= index string-type-index)
+                                   (loop :for c :across s :for i = (character-type-index c)
+                                         :do (consider i)
+                                         ,@(when (> +max-character-type-index+ 1)
+                                             `((when (= i string-type-index) (return))))))))
+                  (t (error "Invalid string designator ~S for ~S" s 'strings-common-element-type))))
+                  :finally (return index)))
+          ''character))
+
+  (defun reduce/strcat (strings &key key start end)
+    "Reduce a list as if by STRCAT, accepting KEY START and END keywords like REDUCE.
+NIL is interpreted as an empty string. A character is interpreted as a string of length one."
+    (when (or start end) (setf strings (subseq strings start end)))
+    (when key (setf strings (mapcar key strings)))
+    (loop :with output = (make-string (loop :for s :in strings
+                                            :sum (if (characterp s) 1 (length s)))
+                                      :element-type (strings-common-element-type strings))
+          :with pos = 0
+          :for input :in strings
+          :do (etypecase input
+                (null)
+                (character (setf (char output pos) input) (incf pos))
+                (string (replace output input :start1 pos) (incf pos (length input))))
+          :finally (return output)))
+
+  (defun strcat (&rest strings)
+    "Concatenate strings.
+NIL is interpreted as an empty string, a character as a string of length one."
+    (reduce/strcat strings))
+
+  (defun first-char (s)
+    "Return the first character of a non-empty string S, or NIL"
+    (and (stringp s) (plusp (length s)) (char s 0)))
+
+  (defun last-char (s)
+    "Return the last character of a non-empty string S, or NIL"
+    (and (stringp s) (plusp (length s)) (char s (1- (length s)))))
+
+  (defun split-string (string &key max (separator '(#\Space #\Tab)))
+    "Split STRING into a list of components separated by
+any of the characters in the sequence SEPARATOR.
+If MAX is specified, then no more than max(1,MAX) components will be returned,
+starting the separation from the end, e.g. when called with arguments
+ \"a.b.c.d.e\" :max 3 :separator \".\" it will return (\"a.b.c\" \"d\" \"e\")."
+    (block ()
+      (let ((list nil) (words 0) (end (length string)))
+        (when (zerop end) (return nil))
+        (flet ((separatorp (char) (find char separator))
+               (done () (return (cons (subseq string 0 end) list))))
+          (loop
+            :for start = (if (and max (>= words (1- max)))
+                             (done)
+                             (position-if #'separatorp string :end end :from-end t))
+            :do (when (null start) (done))
+                (push (subseq string (1+ start) end) list)
+                (incf words)
+                (setf end start))))))
+
+  (defun string-prefix-p (prefix string)
+    "Does STRING begin with PREFIX?"
+    (let* ((x (string prefix))
+           (y (string string))
+           (lx (length x))
+           (ly (length y)))
+      (and (<= lx ly) (string= x y :end2 lx))))
+
+  (defun string-suffix-p (string suffix)
+    "Does STRING end with SUFFIX?"
+    (let* ((x (string string))
+           (y (string suffix))
+           (lx (length x))
+           (ly (length y)))
+      (and (<= ly lx) (string= x y :start1 (- lx ly)))))
+
+  (defun string-enclosed-p (prefix string suffix)
+    "Does STRING begin with PREFIX and end with SUFFIX?"
+    (and (string-prefix-p prefix string)
+         (string-suffix-p string suffix)))
+
+  (defvar +cr+ (coerce #(#\Return) 'string))
+  (defvar +lf+ (coerce #(#\Linefeed) 'string))
+  (defvar +crlf+ (coerce #(#\Return #\Linefeed) 'string))
+
+  (defun stripln (x)
+    "Strip a string X from any ending CR, LF or CRLF.
+Return two values, the stripped string and the ending that was stripped,
+or the original value and NIL if no stripping took place.
+Since our STRCAT accepts NIL as empty string designator,
+the two results passed to STRCAT always reconstitute the original string"
+    (check-type x string)
+    (block nil
+      (flet ((c (end) (when (string-suffix-p x end)
+                        (return (values (subseq x 0 (- (length x) (length end))) end)))))
+        (when x (c +crlf+) (c +lf+) (c +cr+) (values x nil)))))
+
+  (defun standard-case-symbol-name (name-designator)
+    "Given a NAME-DESIGNATOR for a symbol, if it is a symbol, convert it to a string using STRING;
+if it is a string, use STRING-UPCASE on an ANSI CL platform, or STRING on a so-called \"modern\"
+platform such as Allegro with modern syntax."
+    (check-type name-designator (or string symbol))
+    (cond
+      ((or (symbolp name-designator) #+allegro (eq excl:*current-case-mode* :case-sensitive-lower))
+       (string name-designator))
+      ;; Should we be doing something on CLISP?
+      (t (string-upcase name-designator))))
+
+  (defun find-standard-case-symbol (name-designator package-designator &optional (error t))
+    "Find a symbol designated by NAME-DESIGNATOR in a package designated by PACKAGE-DESIGNATOR,
+where STANDARD-CASE-SYMBOL-NAME is used to transform them if these designators are strings.
+If optional ERROR argument is NIL, return NIL instead of an error when the symbol is not found."
+    (find-symbol* (standard-case-symbol-name name-designator)
+                  (etypecase package-designator
+                    ((or package symbol) package-designator)
+                    (string (standard-case-symbol-name package-designator)))
+                  error)))
+
+;;; timestamps: a REAL or a boolean where T=-infinity, NIL=+infinity
+(eval-when (#-lispworks :compile-toplevel :load-toplevel :execute)
+  (deftype timestamp () '(or real boolean)))
+(with-upgradability ()
+  (defun timestamp< (x y)
+    (etypecase x
+      ((eql t) (not (eql y t)))
+      (real (etypecase y
+              ((eql t) nil)
+              (real (< x y))
+              (null t)))
+      (null nil)))
+  (defun timestamps< (list) (loop :for y :in list :for x = nil :then y :always (timestamp< x y)))
+  (defun timestamp*< (&rest list) (timestamps< list))
+  (defun timestamp<= (x y) (not (timestamp< y x)))
+  (defun earlier-timestamp (x y) (if (timestamp< x y) x y))
+  (defun timestamps-earliest (list) (reduce 'earlier-timestamp list :initial-value nil))
+  (defun earliest-timestamp (&rest list) (timestamps-earliest list))
+  (defun later-timestamp (x y) (if (timestamp< x y) y x))
+  (defun timestamps-latest (list) (reduce 'later-timestamp list :initial-value t))
+  (defun latest-timestamp (&rest list) (timestamps-latest list))
+  (define-modify-macro latest-timestamp-f (&rest timestamps) latest-timestamp))
+
+
+;;; Function designators
+(with-upgradability ()
+  (defun ensure-function (fun &key (package :cl))
+    "Coerce the object FUN into a function.
+
+If FUN is a FUNCTION, return it.
+If the FUN is a non-sequence literal constant, return constantly that,
+i.e. for a boolean keyword character number or pathname.
+Otherwise if FUN is a non-literally constant symbol, return its FDEFINITION.
+If FUN is a CONS, return the function that applies its CAR
+to the appended list of the rest of its CDR and the arguments,
+unless the CAR is LAMBDA, in which case the expression is evaluated.
+If FUN is a string, READ a form from it in the specified PACKAGE (default: CL)
+and EVAL that in a (FUNCTION ...) context."
+    (etypecase fun
+      (function fun)
+      ((or boolean keyword character number pathname) (constantly fun))
+      (hash-table #'(lambda (x) (gethash x fun)))
+      (symbol (fdefinition fun))
+      (cons (if (eq 'lambda (car fun))
+                (eval fun)
+                #'(lambda (&rest args) (apply (car fun) (append (cdr fun) args)))))
+      (string (eval `(function ,(with-standard-io-syntax
+                                  (let ((*package* (find-package package)))
+                                    (read-from-string fun))))))))
+
+  (defun access-at (object at)
+    "Given an OBJECT and an AT specifier, list of successive accessors,
+call each accessor on the result of the previous calls.
+An accessor may be an integer, meaning a call to ELT,
+a keyword, meaning a call to GETF,
+NIL, meaning identity,
+a function or other symbol, meaning itself,
+or a list of a function designator and arguments, interpreted as per ENSURE-FUNCTION.
+As a degenerate case, the AT specifier may be an atom of a single such accessor
+instead of a list."
+    (flet ((access (object accessor)
+             (etypecase accessor
+               (function (funcall accessor object))
+               (integer (elt object accessor))
+               (keyword (getf object accessor))
+               (null object)
+               (symbol (funcall accessor object))
+               (cons (funcall (ensure-function accessor) object)))))
+      (if (listp at)
+          (dolist (accessor at object)
+            (setf object (access object accessor)))
+          (access object at))))
+
+  (defun access-at-count (at)
+    "From an AT specification, extract a COUNT of maximum number
+of sub-objects to read as per ACCESS-AT"
+    (cond
+      ((integerp at)
+       (1+ at))
+      ((and (consp at) (integerp (first at)))
+       (1+ (first at)))))
+
+  (defun call-function (function-spec &rest arguments)
+    "Call the function designated by FUNCTION-SPEC as per ENSURE-FUNCTION,
+with the given ARGUMENTS"
+    (apply (ensure-function function-spec) arguments))
+
+  (defun call-functions (function-specs)
+    "For each function in the list FUNCTION-SPECS, in order, call the function as per CALL-FUNCTION"
+    (map () 'call-function function-specs))
+
+  (defun register-hook-function (variable hook &optional call-now-p)
+    "Push the HOOK function (a designator as per ENSURE-FUNCTION) onto the hook VARIABLE.
+When CALL-NOW-P is true, also call the function immediately."
+    (pushnew hook (symbol-value variable) :test 'equal)
+    (when call-now-p (call-function hook))))
+
+
+;;; CLOS
+(with-upgradability ()
+  (defun coerce-class (class &key (package :cl) (super t) (error 'error))
+    "Coerce CLASS to a class that is subclass of SUPER if specified,
+or invoke ERROR handler as per CALL-FUNCTION.
+
+A keyword designates the name a symbol, which when found in either PACKAGE, designates a class.
+-- for backward compatibility, *PACKAGE* is also accepted for now, but this may go in the future.
+A string is read as a symbol while in PACKAGE, the symbol designates a class.
+
+A class object designates itself.
+NIL designates itself (no class).
+A symbol otherwise designates a class by name."
+    (let* ((normalized
+            (typecase class
+              (keyword (or (find-symbol* class package nil)
+                           (find-symbol* class *package* nil)))
+              (string (symbol-call :uiop :safe-read-from-string class :package package))
+              (t class)))
+           (found
+            (etypecase normalized
+              ((or standard-class built-in-class) normalized)
+              ((or null keyword) nil)
+              (symbol (find-class normalized nil nil))))
+           (super-class
+            (etypecase super
+              ((or standard-class built-in-class) super)
+              ((or null keyword) nil)
+              (symbol (find-class super nil nil)))))
+      #+allegro (when found (mop:finalize-inheritance found))
+      (or (and found
+               (or (eq super t) (#-cormanlisp subtypep #+cormanlisp cl::subclassp found super-class))
+               found)
+          (call-function error "Can't coerce ~S to a ~:[class~;subclass of ~:*~S~]" class super)))))
+
+
+;;; Hash-tables
+(with-upgradability ()
+  (defun ensure-gethash (key table default)
+    "Lookup the TABLE for a KEY as by GETHASH, but if not present,
+call the (possibly constant) function designated by DEFAULT as per CALL-FUNCTION,
+set the corresponding entry to the result in the table.
+Return two values: the entry after its optional computation, and whether it was found"
+    (multiple-value-bind (value foundp) (gethash key table)
+      (values
+       (if foundp
+           value
+           (setf (gethash key table) (call-function default)))
+       foundp)))
+
+  (defun list-to-hash-set (list &aux (h (make-hash-table :test 'equal)))
+    "Convert a LIST into hash-table that has the same elements when viewed as a set,
+up to the given equality TEST"
+    (dolist (x list h) (setf (gethash x h) t))))
+
+
+;;; Lexicographic comparison of lists of numbers
+(with-upgradability ()
+  (defun lexicographic< (element< x y)
+    "Lexicographically compare two lists of using the function element< to compare elements.
+element< is a strict total order; the resulting order on X and Y will also be strict."
+    (cond ((null y) nil)
+          ((null x) t)
+          ((funcall element< (car x) (car y)) t)
+          ((funcall element< (car y) (car x)) nil)
+          (t (lexicographic< element< (cdr x) (cdr y)))))
+
+  (defun lexicographic<= (element< x y)
+    "Lexicographically compare two lists of using the function element< to compare elements.
+element< is a strict total order; the resulting order on X and Y will be a non-strict total order."
+    (not (lexicographic< element< y x))))
+
+
+;;; Simple style warnings
+(with-upgradability ()
+  (define-condition simple-style-warning
+      #+sbcl (sb-int:simple-style-warning) #-sbcl (simple-condition style-warning)
+    ())
+
+  (defun style-warn (datum &rest arguments)
+    (etypecase datum
+      (string (warn (make-condition 'simple-style-warning :format-control datum :format-arguments arguments)))
+      (symbol (assert (subtypep datum 'style-warning)) (apply 'warn datum arguments))
+      (style-warning (apply 'warn datum arguments)))))
+
+
+;;; Condition control
+
+(with-upgradability ()
+  (defparameter +simple-condition-format-control-slot+
+    #+abcl 'system::format-control
+    #+allegro 'excl::format-control
+    #+(or clasp ecl mkcl) 'si::format-control
+    #+clisp 'system::$format-control
+    #+clozure 'ccl::format-control
+    #+(or cmucl scl) 'conditions::format-control
+    #+(or gcl lispworks) 'conditions::format-string
+    #+sbcl 'sb-kernel:format-control
+    #-(or abcl allegro clasp clisp clozure cmucl ecl gcl lispworks mkcl sbcl scl) nil
+    "Name of the slot for FORMAT-CONTROL in simple-condition")
+
+  (defun match-condition-p (x condition)
+    "Compare received CONDITION to some pattern X:
+a symbol naming a condition class,
+a simple vector of length 2, arguments to find-symbol* with result as above,
+or a string describing the format-control of a simple-condition."
+    (etypecase x
+      (symbol (typep condition x))
+      ((simple-vector 2)
+       (ignore-errors (typep condition (find-symbol* (svref x 0) (svref x 1) nil))))
+      (function (funcall x condition))
+      (string (and (typep condition 'simple-condition)
+                   ;; On SBCL, it's always set and the check triggers a warning
+                   #+(or allegro clozure cmucl lispworks scl)
+                   (slot-boundp condition +simple-condition-format-control-slot+)
+                   (ignore-errors (equal (simple-condition-format-control condition) x))))))
+
+  (defun match-any-condition-p (condition conditions)
+    "match CONDITION against any of the patterns of CONDITIONS supplied"
+    (loop :for x :in conditions :thereis (match-condition-p x condition)))
+
+  (defun call-with-muffled-conditions (thunk conditions)
+    "calls the THUNK in a context where the CONDITIONS are muffled"
+    (handler-bind ((t #'(lambda (c) (when (match-any-condition-p c conditions)
+                                      (muffle-warning c)))))
+      (funcall thunk)))
+
+  (defmacro with-muffled-conditions ((conditions) &body body)
+    "Shorthand syntax for CALL-WITH-MUFFLED-CONDITIONS"
+    `(call-with-muffled-conditions #'(lambda () ,@body) ,conditions)))
+
+;;; Conditions
+
+(with-upgradability ()
+  (define-condition not-implemented-error (error)
+    ((functionality :initarg :functionality)
+     (format-control :initarg :format-control)
+     (format-arguments :initarg :format-arguments))
+    (:report (lambda (condition stream)
+               (format stream "Not (currently) implemented on ~A: ~S~@[ ~?~]"
+                       (nth-value 1 (symbol-call :uiop :implementation-type))
+                       (slot-value condition 'functionality)
+                       (slot-value condition 'format-control)
+                       (slot-value condition 'format-arguments)))))
+
+  (defun not-implemented-error (functionality &optional format-control &rest format-arguments)
+    "Signal an error because some FUNCTIONALITY is not implemented in the current version
+of the software on the current platform; it may or may not be implemented in different combinations
+of version of the software and of the underlying platform. Optionally, report a formatted error
+message."
+    (error 'not-implemented-error
+           :functionality functionality
+           :format-control format-control
+           :format-arguments format-arguments))
+
+  (define-condition parameter-error (error)
+    ((functionality :initarg :functionality)
+     (format-control :initarg :format-control)
+     (format-arguments :initarg :format-arguments))
+    (:report (lambda (condition stream)
+               (apply 'format stream
+                       (slot-value condition 'format-control)
+                       (slot-value condition 'functionality)
+                       (slot-value condition 'format-arguments)))))
+
+  ;; Note that functionality MUST be passed as the second argument to parameter-error, just after
+  ;; the format-control. If you want it to not appear in first position in actual message, use
+  ;; ~* and ~:* to adjust parameter order.
+  (defun parameter-error (format-control functionality &rest format-arguments)
+    "Signal an error because some FUNCTIONALITY or its specific implementation on a given underlying
+platform does not accept a given parameter or combination of parameters. Report a formatted error
+message, that takes the functionality as its first argument (that can be skipped with ~*)."
+    (error 'parameter-error
+           :functionality functionality
+           :format-control format-control
+           :format-arguments format-arguments)))
+
+(with-upgradability ()
+  (defun boolean-to-feature-expression (value)
+    "Converts a boolean VALUE to a form suitable for testing with #+."
+    (if value
+        '(:and)
+        '(:or)))
+
+  (defun symbol-test-to-feature-expression (name package)
+    "Check if a symbol with a given NAME exists in PACKAGE and returns a
+form suitable for testing with #+."
+    (boolean-to-feature-expression
+     (find-symbol* name package nil))))
+(uiop/package:define-package :uiop/version
+  (:recycle :uiop/version :uiop/utility :asdf)
+  (:use :uiop/common-lisp :uiop/package :uiop/utility)
+  (:export
+   #:*uiop-version*
+   #:parse-version #:unparse-version #:version< #:version<= ;; version support, moved from uiop/utility
+   #:next-version
+   #:deprecated-function-condition #:deprecated-function-name ;; deprecation control
+   #:deprecated-function-style-warning #:deprecated-function-warning
+   #:deprecated-function-error #:deprecated-function-should-be-deleted
+   #:version-deprecation #:with-deprecation))
+(in-package :uiop/version)
+
+(with-upgradability ()
+  (defparameter *uiop-version* "3.3.5")
+
+  (defun unparse-version (version-list)
+    "From a parsed version (a list of natural numbers), compute the version string"
+    (format nil "~{~D~^.~}" version-list))
+
+  (defun parse-version (version-string &optional on-error)
+    "Parse a VERSION-STRING as a series of natural numbers separated by dots.
+Return a (non-null) list of integers if the string is valid;
+otherwise return NIL.
+
+When invalid, ON-ERROR is called as per CALL-FUNCTION before to return NIL,
+with format arguments explaining why the version is invalid.
+ON-ERROR is also called if the version is not canonical
+in that it doesn't print back to itself, but the list is returned anyway."
+    (block nil
+      (unless (stringp version-string)
+        (call-function on-error "~S: ~S is not a string" 'parse-version version-string)
+        (return))
+      (unless (loop :for prev = nil :then c :for c :across version-string
+                    :always (or (digit-char-p c)
+                                (and (eql c #\.) prev (not (eql prev #\.))))
+                    :finally (return (and c (digit-char-p c))))
+        (call-function on-error "~S: ~S doesn't follow asdf version numbering convention"
+                       'parse-version version-string)
+        (return))
+      (let* ((version-list
+               (mapcar #'parse-integer (split-string version-string :separator ".")))
+             (normalized-version (unparse-version version-list)))
+        (unless (equal version-string normalized-version)
+          (call-function on-error "~S: ~S contains leading zeros" 'parse-version version-string))
+        version-list)))
+
+  (defun next-version (version)
+    "When VERSION is not nil, it is a string, then parse it as a version, compute the next version
+and return it as a string."
+    (when version
+      (let ((version-list (parse-version version)))
+        (incf (car (last version-list)))
+        (unparse-version version-list))))
+
+  (defun version< (version1 version2)
+    "Given two version strings, return T if the second is strictly newer"
+    (let ((v1 (parse-version version1 nil))
+          (v2 (parse-version version2 nil)))
+      (lexicographic< '< v1 v2)))
+
+  (defun version<= (version1 version2)
+    "Given two version strings, return T if the second is newer or the same"
+    (not (version< version2 version1))))
+
+
+(with-upgradability ()
+  (define-condition deprecated-function-condition (condition)
+    ((name :initarg :name :reader deprecated-function-name)))
+  (define-condition deprecated-function-style-warning (deprecated-function-condition style-warning) ())
+  (define-condition deprecated-function-warning (deprecated-function-condition warning) ())
+  (define-condition deprecated-function-error (deprecated-function-condition error) ())
+  (define-condition deprecated-function-should-be-deleted (deprecated-function-condition error) ())
+
+  (defun deprecated-function-condition-kind (type)
+    (ecase type
+      ((deprecated-function-style-warning) :style-warning)
+      ((deprecated-function-warning) :warning)
+      ((deprecated-function-error) :error)
+      ((deprecated-function-should-be-deleted) :delete)))
+
+  (defmethod print-object ((c deprecated-function-condition) stream)
+    (let ((name (deprecated-function-name c)))
+      (cond
+        (*print-readably*
+         (let ((fmt "#.(make-condition '~S :name ~S)")
+               (args (list (type-of c) name)))
+           (if *read-eval*
+               (apply 'format stream fmt args)
+               (error "Can't print ~?" fmt args))))
+        (*print-escape*
+         (print-unreadable-object (c stream :type t) (format stream ":name ~S" name)))
+        (t
+         (let ((*package* (find-package :cl))
+               (type (type-of c)))
+           (format stream
+                   (if (eq type 'deprecated-function-should-be-deleted)
+                       "~A: Still defining deprecated function~:P ~{~S~^ ~} that promised to delete"
+                       "~A: Using deprecated function ~S -- please update your code to use a newer API.~
+~@[~%The docstring for this function says:~%~A~%~]")
+                   type name (when (symbolp name) (documentation name 'function))))))))
+
+  (defun notify-deprecated-function (status name)
+    (ecase status
+      ((nil) nil)
+      ((:style-warning) (style-warn 'deprecated-function-style-warning :name name))
+      ((:warning) (warn 'deprecated-function-warning :name name))
+      ((:error) (cerror "USE FUNCTION ANYWAY" 'deprecated-function-error :name name))))
+
+  (defun version-deprecation (version &key (style-warning nil)
+                                        (warning (next-version style-warning))
+                                        (error (next-version warning))
+                                        (delete (next-version error)))
+    "Given a VERSION string, and the starting versions for notifying the programmer of
+various levels of deprecation, return the current level of deprecation as per WITH-DEPRECATION
+that is the highest level that has a declared version older than the specified version.
+Each start version for a level of deprecation can be specified by a keyword argument, or
+if left unspecified, will be the NEXT-VERSION of the immediate lower level of deprecation."
+    (cond
+      ((and delete (version<= delete version)) :delete)
+      ((and error (version<= error version)) :error)
+      ((and warning (version<= warning version)) :warning)
+      ((and style-warning (version<= style-warning version)) :style-warning)))
+
+  (defmacro with-deprecation ((level) &body definitions)
+    "Given a deprecation LEVEL (a form to be EVAL'ed at macro-expansion time), instrument the
+DEFUN and DEFMETHOD forms in DEFINITIONS to notify the programmer of the deprecation of the function
+when it is compiled or called.
+
+Increasing levels (as result from evaluating LEVEL) are: NIL (not deprecated yet),
+:STYLE-WARNING (a style warning is issued when used), :WARNING (a full warning is issued when used),
+:ERROR (a continuable error instead), and :DELETE (it's an error if the code is still there while
+at that level).
+
+Forms other than DEFUN and DEFMETHOD are not instrumented, and you can protect a DEFUN or DEFMETHOD
+from instrumentation by enclosing it in a PROGN."
+    (let ((level (eval level)))
+      (check-type level (member nil :style-warning :warning :error :delete))
+      (when (eq level :delete)
+        (error 'deprecated-function-should-be-deleted :name
+               (mapcar 'second
+                       (remove-if-not #'(lambda (x) (member x '(defun defmethod)))
+                                      definitions :key 'first))))
+      (labels ((instrument (name head body whole)
+                 (if level
+                     (let ((notifiedp
+                            (intern (format nil "*~A-~A-~A-~A*"
+                                            :deprecated-function level name :notified-p))))
+                       (multiple-value-bind (remaining-forms declarations doc-string)
+                           (parse-body body :documentation t :whole whole)
+                         `(progn
+                            (defparameter ,notifiedp nil)
+                            ;; tell some implementations to use the compiler-macro
+                            (declaim (inline ,name))
+                            (define-compiler-macro ,name (&whole form &rest args)
+                              (declare (ignore args))
+                              (notify-deprecated-function ,level ',name)
+                              form)
+                            (,@head ,@(when doc-string (list doc-string)) ,@declarations
+                                    (unless ,notifiedp
+                                      (setf ,notifiedp t)
+                                      (notify-deprecated-function ,level ',name))
+                                    ,@remaining-forms))))
+                     `(progn
+                        (eval-when (:compile-toplevel :load-toplevel :execute)
+                          (setf (compiler-macro-function ',name) nil))
+                        (declaim (notinline ,name))
+                        (,@head ,@body)))))
+        `(progn
+           ,@(loop :for form :in definitions :collect
+               (cond
+                 ((and (consp form) (eq (car form) 'defun))
+                  (instrument (second form) (subseq form 0 3) (subseq form 3) form))
+                 ((and (consp form) (eq (car form) 'defmethod))
+                  (let ((body-start (if (listp (third form)) 3 4)))
+                    (instrument (second form)
+                                (subseq form 0 body-start)
+                                (subseq form body-start)
+                                form)))
+                 (t
+                  form))))))))
+;;;; ---------------------------------------------------------------------------
+;;;; Access to the Operating System
+
+(uiop/package:define-package :uiop/os
+  (:use :uiop/common-lisp :uiop/package :uiop/utility)
+  (:export
+   #:featurep #:os-unix-p #:os-macosx-p #:os-windows-p #:os-genera-p #:detect-os ;; features
+   #:os-cond
+   #:getenv #:getenvp ;; environment variables
+   #:implementation-identifier ;; implementation identifier
+   #:implementation-type #:*implementation-type*
+   #:operating-system #:architecture #:lisp-version-string
+   #:hostname #:getcwd #:chdir
+   ;; Windows shortcut support
+   #:read-null-terminated-string #:read-little-endian
+   #:parse-file-location-info #:parse-windows-shortcut))
+(in-package :uiop/os)
+
+;;; Features
+(with-upgradability ()
+  (defun featurep (x &optional (*features* *features*))
+    "Checks whether a feature expression X is true with respect to the *FEATURES* set,
+as per the CLHS standard for #+ and #-. Beware that just like the CLHS,
+we assume symbols from the KEYWORD package are used, but that unless you're using #+/#-
+your reader will not have magically used the KEYWORD package, so you need specify
+keywords explicitly."
+    (cond
+      ((atom x) (and (member x *features*) t))
+      ((eq :not (car x)) (assert (null (cddr x))) (not (featurep (cadr x))))
+      ((eq :or (car x)) (some #'featurep (cdr x)))
+      ((eq :and (car x)) (every #'featurep (cdr x)))
+      (t (parameter-error "~S: malformed feature specification ~S" 'featurep x))))
+
+  ;; Starting with UIOP 3.1.5, these are runtime tests.
+  ;; You may bind *features* with a copy of what your target system offers to test its properties.
+  (defun os-macosx-p ()
+    "Is the underlying operating system MacOS X?"
+    ;; OS-MACOSX is not mutually exclusive with OS-UNIX,
+    ;; in fact the former implies the latter.
+    (featurep '(:or :darwin (:and :allegro :macosx) (:and :clisp :macos))))
+
+  (defun os-unix-p ()
+    "Is the underlying operating system some Unix variant?"
+    (or (featurep '(:or :unix :cygwin :haiku)) (os-macosx-p)))
+
+  (defun os-windows-p ()
+    "Is the underlying operating system Microsoft Windows?"
+    (and (not (os-unix-p)) (featurep '(:or :win32 :windows :mswindows :mingw32 :mingw64))))
+
+  (defun os-genera-p ()
+    "Is the underlying operating system Genera (running on a Symbolics Lisp Machine)?"
+    (featurep :genera))
+
+  (defun os-oldmac-p ()
+    "Is the underlying operating system an (emulated?) MacOS 9 or earlier?"
+    (featurep :mcl))
+
+  (defun os-haiku-p ()
+    "Is the underlying operating system Haiku?"
+    (featurep :haiku))
+
+  (defun os-mezzano-p ()
+    "Is the underlying operating system Mezzano?"
+    (featurep :mezzano))
+
+  (defun detect-os ()
+    "Detects the current operating system. Only needs be run at compile-time,
+except on ABCL where it might change between FASL compilation and runtime."
+    (loop :with o
+          :for (feature . detect) :in '((:os-unix . os-unix-p) (:os-macosx . os-macosx-p)
+                                        (:os-windows . os-windows-p)
+                                        (:os-genera . os-genera-p) (:os-oldmac . os-oldmac-p)
+                                        (:os-haiku . os-haiku-p)
+                                        (:os-mezzano . os-mezzano-p))
+          :when (and (or (not o) (eq feature :os-macosx) (eq feature :os-haiku)) (funcall detect))
+            :do (setf o feature) (pushnew feature *features*)
+          :else :do (setf *features* (remove feature *features*))
+          :finally
+             (return (or o (error "Congratulations for trying ASDF on an operating system~%~
+that is neither Unix, nor Windows, nor Genera, nor even old MacOS.~%Now you port it.")))))
+
+  (defmacro os-cond (&rest clauses)
+    #+abcl `(cond ,@clauses)
+    #-abcl (loop :for (test . body) :in clauses :when (eval test) :return `(progn ,@body)))
+
+  (detect-os))
+
+;;;; Environment variables: getting them, and parsing them.
+(with-upgradability ()
+  (defun getenv (x)
+    "Query the environment, as in C getenv.
+Beware: may return empty string if a variable is present but empty;
+use getenvp to return NIL in such a case."
+    (declare (ignorable x))
+    #+(or abcl clasp clisp ecl xcl) (ext:getenv x)
+    #+allegro (sys:getenv x)
+    #+clozure (ccl:getenv x)
+    #+cmucl (unix:unix-getenv x)
+    #+scl (cdr (assoc x ext:*environment-list* :test #'string=))
+    #+cormanlisp
+    (let* ((buffer (ct:malloc 1))
+           (cname (ct:lisp-string-to-c-string x))
+           (needed-size (win:getenvironmentvariable cname buffer 0))
+           (buffer1 (ct:malloc (1+ needed-size))))
+      (prog1 (if (zerop (win:getenvironmentvariable cname buffer1 needed-size))
+                 nil
+                 (ct:c-string-to-lisp-string buffer1))
+        (ct:free buffer)
+        (ct:free buffer1)))
+    #+gcl (system:getenv x)
+    #+(or genera mezzano) nil
+    #+lispworks (lispworks:environment-variable x)
+    #+mcl (ccl:with-cstrs ((name x))
+            (let ((value (_getenv name)))
+              (unless (ccl:%null-ptr-p value)
+                (ccl:%get-cstring value))))
+    #+mkcl (#.(or (find-symbol* 'getenv :si nil) (find-symbol* 'getenv :mk-ext nil)) x)
+    #+sbcl (sb-ext:posix-getenv x)
+    #-(or abcl allegro clasp clisp clozure cmucl cormanlisp ecl gcl genera lispworks mcl mezzano mkcl sbcl scl xcl)
+    (not-implemented-error 'getenv))
+
+  (defsetf getenv (x) (val)
+    "Set an environment variable."
+    (declare (ignorable x val))
+    #+allegro `(setf (sys:getenv ,x) ,val)
+    #+clasp `(ext:setenv ,x ,val)
+    #+clisp `(system::setenv ,x ,val)
+    #+clozure `(ccl:setenv ,x ,val)
+    #+cmucl `(unix:unix-setenv ,x ,val 1)
+    #+(or ecl clasp) `(ext:setenv ,x ,val)
+    #+lispworks `(setf (lispworks:environment-variable ,x) ,val)
+    #+mkcl `(mkcl:setenv ,x ,val)
+    #+sbcl `(progn (require :sb-posix) (symbol-call :sb-posix :setenv ,x ,val 1))
+    #-(or allegro clasp clisp clozure cmucl ecl lispworks mkcl sbcl)
+    '(not-implemented-error '(setf getenv)))
+
+  (defun getenvp (x)
+    "Predicate that is true if the named variable is present in the libc environment,
+then returning the non-empty string value of the variable"
+    (let ((g (getenv x))) (and (not (emptyp g)) g))))
+
+
+;;;; implementation-identifier
+;;
+;; produce a string to identify current implementation.
+;; Initially stolen from SLIME's SWANK, completely rewritten since.
+;; We're back to runtime checking, for the sake of e.g. ABCL.
+
+(with-upgradability ()
+  (defun first-feature (feature-sets)
+    "A helper for various feature detection functions"
+    (dolist (x feature-sets)
+      (multiple-value-bind (short long feature-expr)
+          (if (consp x)
+              (values (first x) (second x) (cons :or (rest x)))
+              (values x x x))
+        (when (featurep feature-expr)
+          (return (values short long))))))
+
+  (defun implementation-type ()
+    "The type of Lisp implementation used, as a short UIOP-standardized keyword"
+    (first-feature
+     '(:abcl (:acl :allegro) (:ccl :clozure) :clisp (:corman :cormanlisp)
+       (:cmu :cmucl :cmu) :clasp :ecl :gcl
+       (:lwpe :lispworks-personal-edition) (:lw :lispworks)
+       :mcl :mezzano :mkcl :sbcl :scl (:smbx :symbolics) :xcl)))
+
+  (defvar *implementation-type* (implementation-type)
+    "The type of Lisp implementation used, as a short UIOP-standardized keyword")
+
+  (defun operating-system ()
+    "The operating system of the current host"
+    (first-feature
+     '(:cygwin
+       (:win :windows :mswindows :win32 :mingw32) ;; try cygwin first!
+       (:linux :linux :linux-target) ;; for GCL at least, must appear before :bsd
+       (:macosx :macosx :darwin :darwin-target :apple) ; also before :bsd
+       (:solaris :solaris :sunos)
+       (:bsd :bsd :freebsd :netbsd :openbsd :dragonfly)
+       :unix
+       :genera
+       :mezzano)))
+
+  (defun architecture ()
+    "The CPU architecture of the current host"
+    (first-feature
+     '((:x64 :x86-64 :x86_64 :x8664-target :amd64 (:and :word-size=64 :pc386))
+       (:x86 :x86 :i386 :i486 :i586 :i686 :pentium3 :pentium4 :pc386 :iapx386 :x8632-target)
+       (:ppc64 :ppc64 :ppc64-target) (:ppc32 :ppc32 :ppc32-target :ppc :powerpc)
+       :hppa64 :hppa :sparc64 (:sparc32 :sparc32 :sparc)
+       :mipsel :mipseb :mips :alpha
+       (:arm64 :arm64 :aarch64 :armv8l :armv8b :aarch64_be :|aarch64|)
+       (:arm :arm :arm-target) :vlm :imach
+       ;; Java comes last: if someone uses C via CFFI or otherwise JNA or JNI,
+       ;; we may have to segregate the code still by architecture.
+       (:java :java :java-1.4 :java-1.5 :java-1.6 :java-1.7))))
+
+  #+clozure
+  (defun ccl-fasl-version ()
+    ;; the fasl version is target-dependent from CCL 1.8 on.
+    (or (let ((s 'ccl::target-fasl-version))
+          (and (fboundp s) (funcall s)))
+        (and (boundp 'ccl::fasl-version)
+             (symbol-value 'ccl::fasl-version))
+        (error "Can't determine fasl version.")))
+
+  (defun lisp-version-string ()
+    "return a string that identifies the current Lisp implementation version"
+    (let ((s (lisp-implementation-version)))
+      (car ; as opposed to OR, this idiom prevents some unreachable code warning
+       (list
+        #+allegro
+        (format nil "~A~@[~A~]~@[~A~]~@[~A~]"
+                excl::*common-lisp-version-number*
+                ;; M means "modern", as opposed to ANSI-compatible mode (which I consider default)
+                (and (eq excl:*current-case-mode* :case-sensitive-lower) "M")
+                ;; Note if not using International ACL
+                ;; see http://www.franz.com/support/documentation/8.1/doc/operators/excl/ics-target-case.htm
+                (excl:ics-target-case (:-ics "8"))
+                (and (member :smp *features*) "S"))
+        #+armedbear (format nil "~a-fasl~a" s system::*fasl-version*)
+        #+clisp
+        (subseq s 0 (position #\space s)) ; strip build information (date, etc.)
+        #+clozure
+        (format nil "~d.~d-f~d" ; shorten for windows
+                ccl::*openmcl-major-version*
+                ccl::*openmcl-minor-version*
+                (logand (ccl-fasl-version) #xFF))
+        #+cmucl (substitute #\- #\/ s)
+        #+scl (format nil "~A~A" s
+                      ;; ANSI upper case vs lower case.
+                      (ecase ext:*case-mode* (:upper "") (:lower "l")))
+        #+ecl (format nil "~A~@[-~A~]" s
+                      (let ((vcs-id (ext:lisp-implementation-vcs-id)))
+                        (unless (equal vcs-id "UNKNOWN")
+                          (subseq vcs-id 0 (min (length vcs-id) 8)))))
+        #+gcl (subseq s (1+ (position #\space s)))
+        #+genera
+        (multiple-value-bind (major minor) (sct:get-system-version "System")
+          (format nil "~D.~D" major minor))
+        #+mcl (subseq s 8) ; strip the leading "Version "
+        #+mezzano (format nil "~A-~D"
+                          (subseq s 0 (position #\space s)) ; strip commit hash
+                          sys.int::*llf-version*)
+        ;; seems like there should be a shorter way to do this, like ACALL.
+        #+mkcl (or
+                (let ((fname (find-symbol* '#:git-describe-this-mkcl :mkcl nil)))
+                  (when (and fname (fboundp fname))
+                    (funcall fname)))
+                s)
+        s))))
+
+  (defun implementation-identifier ()
+    "Return a string that identifies the ABI of the current implementation,
+suitable for use as a directory name to segregate Lisp FASLs, C dynamic libraries, etc."
+    (substitute-if
+     #\_ #'(lambda (x) (find x " /:;&^\\|?<>(){}[]$#`'\""))
+     (format nil "~(~a~@{~@[-~a~]~}~)"
+             (or (implementation-type) (lisp-implementation-type))
+             (lisp-version-string)
+             (or (operating-system) (software-type))
+             (or (architecture) (machine-type))))))
+
+
+;;;; Other system information
+
+(with-upgradability ()
+  (defun hostname ()
+    "return the hostname of the current host"
+    #+(or abcl clasp clozure cmucl ecl genera lispworks mcl mezzano mkcl sbcl scl xcl) (machine-instance)
+    #+cormanlisp "localhost" ;; is there a better way? Does it matter?
+    #+allegro (symbol-call :excl.osi :gethostname)
+    #+clisp (first (split-string (machine-instance) :separator " "))
+    #+gcl (system:gethostname)))
+
+
+;;; Current directory
+(with-upgradability ()
+
+  #+cmucl
+  (defun parse-unix-namestring* (unix-namestring)
+    "variant of LISP::PARSE-UNIX-NAMESTRING that returns a pathname object"
+    (multiple-value-bind (host device directory name type version)
+        (lisp::parse-unix-namestring unix-namestring 0 (length unix-namestring))
+      (make-pathname :host (or host lisp::*unix-host*) :device device
+                     :directory directory :name name :type type :version version)))
+
+  (defun getcwd ()
+    "Get the current working directory as per POSIX getcwd(3), as a pathname object"
+    (or #+(or abcl genera mezzano xcl) (truename *default-pathname-defaults*) ;; d-p-d is canonical!
+        #+allegro (excl::current-directory)
+        #+clisp (ext:default-directory)
+        #+clozure (ccl:current-directory)
+        #+(or cmucl scl) (#+cmucl parse-unix-namestring* #+scl lisp::parse-unix-namestring
+                        (strcat (nth-value 1 (unix:unix-current-directory)) "/"))
+        #+cormanlisp (pathname (pl::get-current-directory)) ;; Q: what type does it return?
+        #+(or clasp ecl) (ext:getcwd)
+        #+gcl (let ((*default-pathname-defaults* #p"")) (truename #p""))
+        #+lispworks (hcl:get-working-directory)
+        #+mkcl (mk-ext:getcwd)
+        #+sbcl (sb-ext:parse-native-namestring (sb-unix:posix-getcwd/))
+        #+xcl (extensions:current-directory)
+        (not-implemented-error 'getcwd)))
+
+  (defun chdir (x)
+    "Change current directory, as per POSIX chdir(2), to a given pathname object"
+    (if-let (x (pathname x))
+      #+(or abcl genera mezzano xcl) (setf *default-pathname-defaults* (truename x)) ;; d-p-d is canonical!
+      #+allegro (excl:chdir x)
+      #+clisp (ext:cd x)
+      #+clozure (setf (ccl:current-directory) x)
+      #+(or cmucl scl) (unix:unix-chdir (ext:unix-namestring x))
+      #+cormanlisp (unless (zerop (win32::_chdir (namestring x)))
+                     (error "Could not set current directory to ~A" x))
+      #+ecl (ext:chdir x)
+      #+clasp (ext:chdir x t)
+      #+gcl (system:chdir x)
+      #+lispworks (hcl:change-directory x)
+      #+mkcl (mk-ext:chdir x)
+      #+sbcl (progn (require :sb-posix) (symbol-call :sb-posix :chdir (sb-ext:native-namestring x)))
+      #-(or abcl allegro clasp clisp clozure cmucl cormanlisp ecl gcl genera lispworks mkcl sbcl scl xcl)
+      (not-implemented-error 'chdir))))
+
+
+;;;; -----------------------------------------------------------------
+;;;; Windows shortcut support.  Based on:
+;;;;
+;;;; Jesse Hager: The Windows Shortcut File Format.
+;;;; http://www.wotsit.org/list.asp?fc=13
+
+#-(or clisp genera) ; CLISP doesn't need it, and READ-SEQUENCE annoys old Genera that doesn't need it
+(with-upgradability ()
+  (defparameter *link-initial-dword* 76)
+  (defparameter *link-guid* #(1 20 2 0 0 0 0 0 192 0 0 0 0 0 0 70))
+
+  (defun read-null-terminated-string (s)
+    "Read a null-terminated string from an octet stream S"
+    ;; note: doesn't play well with UNICODE
+    (with-output-to-string (out)
+      (loop :for code = (read-byte s)
+            :until (zerop code)
+            :do (write-char (code-char code) out))))
+
+  (defun read-little-endian (s &optional (bytes 4))
+    "Read a number in little-endian format from an byte (octet) stream S,
+the number having BYTES octets (defaulting to 4)."
+    (loop :for i :from 0 :below bytes
+          :sum (ash (read-byte s) (* 8 i))))
+
+  (defun parse-file-location-info (s)
+    "helper to parse-windows-shortcut"
+    (let ((start (file-position s))
+          (total-length (read-little-endian s))
+          (end-of-header (read-little-endian s))
+          (fli-flags (read-little-endian s))
+          (local-volume-offset (read-little-endian s))
+          (local-offset (read-little-endian s))
+          (network-volume-offset (read-little-endian s))
+          (remaining-offset (read-little-endian s)))
+      (declare (ignore total-length end-of-header local-volume-offset))
+      (unless (zerop fli-flags)
+        (cond
+          ((logbitp 0 fli-flags)
+           (file-position s (+ start local-offset)))
+          ((logbitp 1 fli-flags)
+           (file-position s (+ start
+                               network-volume-offset
+                               #x14))))
+        (strcat (read-null-terminated-string s)
+                (progn
+                  (file-position s (+ start remaining-offset))
+                  (read-null-terminated-string s))))))
+
+  (defun parse-windows-shortcut (pathname)
+    "From a .lnk windows shortcut, extract the pathname linked to"
+    ;; NB: doesn't do much checking & doesn't look like it will work well with UNICODE.
+    (with-open-file (s pathname :element-type '(unsigned-byte 8))
+      (handler-case
+          (when (and (= (read-little-endian s) *link-initial-dword*)
+                     (let ((header (make-array (length *link-guid*))))
+                       (read-sequence header s)
+                       (equalp header *link-guid*)))
+            (let ((flags (read-little-endian s)))
+              (file-position s 76)        ;skip rest of header
+              (when (logbitp 0 flags)
+                ;; skip shell item id list
+                (let ((length (read-little-endian s 2)))
+                  (file-position s (+ length (file-position s)))))
+              (cond
+                ((logbitp 1 flags)
+                 (parse-file-location-info s))
+                (t
+                 (when (logbitp 2 flags)
+                   ;; skip description string
+                   (let ((length (read-little-endian s 2)))
+                     (file-position s (+ length (file-position s)))))
+                 (when (logbitp 3 flags)
+                   ;; finally, our pathname
+                   (let* ((length (read-little-endian s 2))
+                          (buffer (make-array length)))
+                     (read-sequence buffer s)
+                     (map 'string #'code-char buffer)))))))
+        (end-of-file (c)
+          (declare (ignore c))
+          nil)))))
+
+
+;;;; -------------------------------------------------------------------------
+;;;; Portability layer around Common Lisp pathnames
+;; This layer allows for portable manipulation of pathname objects themselves,
+;; which all is necessary prior to any access the filesystem or environment.
+
+(uiop/package:define-package :uiop/pathname
+  (:nicknames :asdf/pathname) ;; deprecated. Used by ceramic
+  (:use :uiop/common-lisp :uiop/package :uiop/utility :uiop/os)
+  (:export
+   ;; Making and merging pathnames, portably
+   #:normalize-pathname-directory-component #:denormalize-pathname-directory-component
+   #:merge-pathname-directory-components #:*unspecific-pathname-type* #:make-pathname*
+   #:make-pathname-component-logical #:make-pathname-logical
+   #:merge-pathnames*
+   #:nil-pathname #:*nil-pathname* #:with-pathname-defaults
+   ;; Predicates
+   #:pathname-equal #:logical-pathname-p #:physical-pathname-p #:physicalize-pathname
+   #:absolute-pathname-p #:relative-pathname-p #:hidden-pathname-p #:file-pathname-p
+   ;; Directories
+   #:pathname-directory-pathname #:pathname-parent-directory-pathname
+   #:directory-pathname-p #:ensure-directory-pathname
+   ;; Parsing filenames
+   #:split-name-type #:parse-unix-namestring #:unix-namestring
+   #:split-unix-namestring-directory-components
+   ;; Absolute and relative pathnames
+   #:subpathname #:subpathname*
+   #:ensure-absolute-pathname
+   #:pathname-root #:pathname-host-pathname
+   #:subpathp #:enough-pathname #:with-enough-pathname #:call-with-enough-pathname
+   ;; Checking constraints
+   #:ensure-pathname ;; implemented in filesystem.lisp to accommodate for existence constraints
+   ;; Wildcard pathnames
+   #:*wild* #:*wild-file* #:*wild-file-for-directory* #:*wild-directory*
+   #:*wild-inferiors* #:*wild-path* #:wilden
+   ;; Translate a pathname
+   #:relativize-directory-component #:relativize-pathname-directory
+   #:directory-separator-for-host #:directorize-pathname-host-device
+   #:translate-pathname*
+   #:*output-translation-function*))
+(in-package :uiop/pathname)
+
+;;; Normalizing pathnames across implementations
+
+(with-upgradability ()
+  (defun normalize-pathname-directory-component (directory)
+    "Convert the DIRECTORY component from a format usable by the underlying
+implementation's MAKE-PATHNAME and other primitives to a CLHS-standard format
+that is a list and not a string."
+    (cond
+      #-(or cmucl sbcl scl) ;; these implementations already normalize directory components.
+      ((stringp directory) `(:absolute ,directory))
+      ((or (null directory)
+           (and (consp directory) (member (first directory) '(:absolute :relative))))
+       directory)
+      #+gcl
+      ((consp directory)
+       (cons :relative directory))
+      (t
+       (parameter-error (compatfmt "~@<~S: Unrecognized pathname directory component ~S~@:>")
+                        'normalize-pathname-directory-component directory))))
+
+  (defun denormalize-pathname-directory-component (directory-component)
+    "Convert the DIRECTORY-COMPONENT from a CLHS-standard format to a format usable
+by the underlying implementation's MAKE-PATHNAME and other primitives"
+    directory-component)
+
+  (defun merge-pathname-directory-components (specified defaults)
+    "Helper for MERGE-PATHNAMES* that handles directory components"
+    (let ((directory (normalize-pathname-directory-component specified)))
+      (ecase (first directory)
+        ((nil) defaults)
+        (:absolute specified)
+        (:relative
+         (let ((defdir (normalize-pathname-directory-component defaults))
+               (reldir (cdr directory)))
+           (cond
+             ((null defdir)
+              directory)
+             ((not (eq :back (first reldir)))
+              (append defdir reldir))
+             (t
+              (loop :with defabs = (first defdir)
+                    :with defrev = (reverse (rest defdir))
+                    :while (and (eq :back (car reldir))
+                                (or (and (eq :absolute defabs) (null defrev))
+                                    (stringp (car defrev))))
+                    :do (pop reldir) (pop defrev)
+                    :finally (return (cons defabs (append (reverse defrev) reldir)))))))))))
+
+  ;; Giving :unspecific as :type argument to make-pathname is not portable.
+  ;; See CLHS make-pathname and 19.2.2.2.3.
+  ;; This will be :unspecific if supported, or NIL if not.
+  (defparameter *unspecific-pathname-type*
+    #+(or abcl allegro clozure cmucl lispworks sbcl scl) :unspecific
+    #+(or genera clasp clisp ecl mkcl gcl xcl #|These haven't been tested:|# cormanlisp mcl mezzano) nil
+    "Unspecific type component to use with the underlying implementation's MAKE-PATHNAME")
+
+  (defun make-pathname* (&rest keys &key directory host device name type version defaults
+                                      #+scl &allow-other-keys)
+    "Takes arguments like CL:MAKE-PATHNAME in the CLHS, and
+   tries hard to make a pathname that will actually behave as documented,
+   despite the peculiarities of each implementation. DEPRECATED: just use MAKE-PATHNAME."
+    (declare (ignore host device directory name type version defaults))
+    (apply 'make-pathname keys))
+
+  (defun make-pathname-component-logical (x)
+    "Make a pathname component suitable for use in a logical-pathname"
+    (typecase x
+      ((eql :unspecific) nil)
+      #+clisp (string (string-upcase x))
+      #+clisp (cons (mapcar 'make-pathname-component-logical x))
+      (t x)))
+
+  (defun make-pathname-logical (pathname host)
+    "Take a PATHNAME's directory, name, type and version components,
+and make a new pathname with corresponding components and specified logical HOST"
+    (make-pathname
+     :host host
+     :directory (make-pathname-component-logical (pathname-directory pathname))
+     :name (make-pathname-component-logical (pathname-name pathname))
+     :type (make-pathname-component-logical (pathname-type pathname))
+     :version (make-pathname-component-logical (pathname-version pathname))))
+
+  (defun merge-pathnames* (specified &optional (defaults *default-pathname-defaults*))
+    "MERGE-PATHNAMES* is like MERGE-PATHNAMES except that
+if the SPECIFIED pathname does not have an absolute directory,
+then the HOST and DEVICE both come from the DEFAULTS, whereas
+if the SPECIFIED pathname does have an absolute directory,
+then the HOST and DEVICE both come from the SPECIFIED pathname.
+This is what users want on a modern Unix or Windows operating system,
+unlike the MERGE-PATHNAMES behavior.
+Also, if either argument is NIL, then the other argument is returned unmodified;
+this is unlike MERGE-PATHNAMES which always merges with a pathname,
+by default *DEFAULT-PATHNAME-DEFAULTS*, which cannot be NIL."
+    (when (null specified) (return-from merge-pathnames* defaults))
+    (when (null defaults) (return-from merge-pathnames* specified))
+    #+scl
+    (ext:resolve-pathname specified defaults)
+    #-scl
+    (let* ((specified (pathname specified))
+           (defaults (pathname defaults))
+           (directory (normalize-pathname-directory-component (pathname-directory specified)))
+           (name (or (pathname-name specified) (pathname-name defaults)))
+           (type (or (pathname-type specified) (pathname-type defaults)))
+           (version (or (pathname-version specified) (pathname-version defaults))))
+      (labels ((unspecific-handler (p)
+                 (if (typep p 'logical-pathname) #'make-pathname-component-logical #'identity)))
+        (multiple-value-bind (host device directory unspecific-handler)
+            (ecase (first directory)
+              ((:absolute)
+               (values (pathname-host specified)
+                       (pathname-device specified)
+                       directory
+                       (unspecific-handler specified)))
+              ((nil :relative)
+               (values (pathname-host defaults)
+                       (pathname-device defaults)
+                       (merge-pathname-directory-components directory (pathname-directory defaults))
+                       (unspecific-handler defaults))))
+          (make-pathname :host host :device device :directory directory
+                         :name (funcall unspecific-handler name)
+                         :type (funcall unspecific-handler type)
+                         :version (funcall unspecific-handler version))))))
+
+  (defun logical-pathname-p (x)
+    "is X a logical-pathname?"
+    (typep x 'logical-pathname))
+
+  (defun physical-pathname-p (x)
+    "is X a pathname that is not a logical-pathname?"
+    (and (pathnamep x) (not (logical-pathname-p x))))
+
+  (defun physicalize-pathname (x)
+    "if X is a logical pathname, use translate-logical-pathname on it."
+    ;; Ought to be the same as translate-logical-pathname, except the latter borks on CLISP
+    (let ((p (when x (pathname x))))
+      (if (logical-pathname-p p) (translate-logical-pathname p) p)))
+
+  (defun nil-pathname (&optional (defaults *default-pathname-defaults*))
+    "A pathname that is as neutral as possible for use as defaults
+when merging, making or parsing pathnames"
+    ;; 19.2.2.2.1 says a NIL host can mean a default host;
+    ;; see also "valid physical pathname host" in the CLHS glossary, that suggests
+    ;; strings and lists of strings or :unspecific
+    ;; But CMUCL decides to die on NIL.
+    ;; MCL has issues with make-pathname, nil and defaulting
+    (declare (ignorable defaults))
+    #.`(make-pathname :directory nil :name nil :type nil :version nil
+                      :device (or #+(and mkcl os-unix) :unspecific)
+                      :host (or #+cmucl lisp::*unix-host* #+(and mkcl os-unix) "localhost")
+                      #+scl ,@'(:scheme nil :scheme-specific-part nil
+                                :username nil :password nil :parameters nil :query nil :fragment nil)
+                      ;; the default shouldn't matter, but we really want something physical
+                      #-mcl ,@'(:defaults defaults)))
+
+  (defvar *nil-pathname* (nil-pathname (physicalize-pathname (user-homedir-pathname)))
+    "A pathname that is as neutral as possible for use as defaults
+when merging, making or parsing pathnames")
+
+  (defmacro with-pathname-defaults ((&optional defaults) &body body)
+    "Execute BODY in a context where the *DEFAULT-PATHNAME-DEFAULTS* is as specified,
+where leaving the defaults NIL or unspecified means a (NIL-PATHNAME), except
+on ABCL, Genera and XCL, where it remains unchanged for it doubles as current-directory."
+    `(let ((*default-pathname-defaults*
+             ,(or defaults
+                  #-(or abcl genera xcl) '*nil-pathname*
+                  #+(or abcl genera xcl) '*default-pathname-defaults*)))
+       ,@body)))
+
+
+;;; Some pathname predicates
+(with-upgradability ()
+  (defun pathname-equal (p1 p2)
+    "Are the two pathnames P1 and P2 reasonably equal in the paths they denote?"
+    (when (stringp p1) (setf p1 (pathname p1)))
+    (when (stringp p2) (setf p2 (pathname p2)))
+    (flet ((normalize-component (x)
+             (unless (member x '(nil :unspecific :newest (:relative)) :test 'equal)
+               x)))
+      (macrolet ((=? (&rest accessors)
+                   (flet ((frob (x)
+                            (reduce 'list (cons 'normalize-component accessors)
+                                    :initial-value x :from-end t)))
+                     `(equal ,(frob 'p1) ,(frob 'p2)))))
+        (or (and (null p1) (null p2))
+            (and (pathnamep p1) (pathnamep p2)
+                 (and (=? pathname-host)
+                      #-(and mkcl os-unix) (=? pathname-device)
+                      (=? normalize-pathname-directory-component pathname-directory)
+                      (=? pathname-name)
+                      (=? pathname-type)
+                      #-mkcl (=? pathname-version)))))))
+
+  (defun absolute-pathname-p (pathspec)
+    "If PATHSPEC is a pathname or namestring object that parses as a pathname
+possessing an :ABSOLUTE directory component, return the (parsed) pathname.
+Otherwise return NIL"
+    (and pathspec
+         (typep pathspec '(or null pathname string))
+         (let ((pathname (pathname pathspec)))
+           (and (eq :absolute (car (normalize-pathname-directory-component
+                                    (pathname-directory pathname))))
+                pathname))))
+
+  (defun relative-pathname-p (pathspec)
+    "If PATHSPEC is a pathname or namestring object that parses as a pathname
+possessing a :RELATIVE or NIL directory component, return the (parsed) pathname.
+Otherwise return NIL"
+    (and pathspec
+         (typep pathspec '(or null pathname string))
+         (let* ((pathname (pathname pathspec))
+                (directory (normalize-pathname-directory-component
+                            (pathname-directory pathname))))
+           (when (or (null directory) (eq :relative (car directory)))
+             pathname))))
+
+  (defun hidden-pathname-p (pathname)
+    "Return a boolean that is true if the pathname is hidden as per Unix style,
+i.e. its name starts with a dot."
+    (and pathname (equal (first-char (pathname-name pathname)) #\.)))
+
+  (defun file-pathname-p (pathname)
+    "Does PATHNAME represent a file, i.e. has a non-null NAME component?
+
+Accepts NIL, a string (converted through PARSE-NAMESTRING) or a PATHNAME.
+
+Note that this does _not_ check to see that PATHNAME points to an
+actually-existing file.
+
+Returns the (parsed) PATHNAME when true"
+    (when pathname
+      (let ((pathname (pathname pathname)))
+        (unless (and (member (pathname-name pathname) '(nil :unspecific "") :test 'equal)
+                     (member (pathname-type pathname) '(nil :unspecific "") :test 'equal))
+          pathname)))))
+
+
+;;; Directory pathnames
+(with-upgradability ()
+  (defun pathname-directory-pathname (pathname)
+    "Returns a new pathname with same HOST, DEVICE, DIRECTORY as PATHNAME,
+and NIL NAME, TYPE and VERSION components"
+    (when pathname
+      (make-pathname :name nil :type nil :version nil :defaults pathname)))
+
+  (defun pathname-parent-directory-pathname (pathname)
+    "Returns a new pathname that corresponds to the parent of the current pathname's directory,
+i.e. removing one level of depth in the DIRECTORY component. e.g. if pathname is
+Unix pathname /foo/bar/baz/file.type then return /foo/bar/"
+    (when pathname
+      (make-pathname :name nil :type nil :version nil
+                     :directory (merge-pathname-directory-components
+                                 '(:relative :back) (pathname-directory pathname))
+                     :defaults pathname)))
+
+  (defun directory-pathname-p (pathname)
+    "Does PATHNAME represent a directory?
+
+A directory-pathname is a pathname _without_ a filename. The three
+ways that the filename components can be missing are for it to be NIL,
+:UNSPECIFIC or the empty string.
+
+Note that this does _not_ check to see that PATHNAME points to an
+actually-existing directory."
+    (when pathname
+      ;; I tried using Allegro's excl:file-directory-p, but this cannot be done,
+      ;; because it rejects apparently legal pathnames as
+      ;; ill-formed. [2014/02/10:rpg]
+      (let ((pathname (pathname pathname)))
+        (flet ((check-one (x)
+                 (member x '(nil :unspecific) :test 'equal)))
+          (and (not (wild-pathname-p pathname))
+               (check-one (pathname-name pathname))
+               (check-one (pathname-type pathname))
+               t)))))
+
+  (defun ensure-directory-pathname (pathspec &optional (on-error 'error))
+    "Converts the non-wild pathname designator PATHSPEC to directory form."
+    (cond
+      ((stringp pathspec)
+       (ensure-directory-pathname (pathname pathspec)))
+      ((not (pathnamep pathspec))
+       (call-function on-error (compatfmt "~@<Invalid pathname designator ~S~@:>") pathspec))
+      ((wild-pathname-p pathspec)
+       (call-function on-error (compatfmt "~@<Can't reliably convert wild pathname ~3i~_~S~@:>") pathspec))
+      ((directory-pathname-p pathspec)
+       pathspec)
+      (t
+       (handler-case
+           (make-pathname :directory (append (or (normalize-pathname-directory-component
+                                                  (pathname-directory pathspec))
+                                                 (list :relative))
+                                             (list #-genera (file-namestring pathspec)
+                                                   ;; On Genera's native filesystem (LMFS),
+                                                   ;; directories have a type and version
+                                                   ;; which must be ignored when converting
+                                                   ;; to a directory pathname
+                                                   #+genera (if (typep pathspec 'fs:lmfs-pathname)
+                                                                (pathname-name pathspec)
+                                                                (file-namestring pathspec))))
+                          :name nil :type nil :version nil :defaults pathspec)
+         (error (c) (call-function on-error (compatfmt "~@<error while trying to create a directory pathname for ~S: ~A~@:>") pathspec c)))))))
+
+
+;;; Parsing filenames
+(with-upgradability ()
+  (declaim (ftype function ensure-pathname)) ; forward reference
+
+  (defun split-unix-namestring-directory-components
+      (unix-namestring &key ensure-directory dot-dot)
+    "Splits the path string UNIX-NAMESTRING, returning four values:
+A flag that is either :absolute or :relative, indicating
+   how the rest of the values are to be interpreted.
+A directory path --- a list of strings and keywords, suitable for
+   use with MAKE-PATHNAME when prepended with the flag value.
+   Directory components with an empty name or the name . are removed.
+   Any directory named .. is read as DOT-DOT, or :BACK if it's NIL (not :UP).
+A last-component, either a file-namestring including type extension,
+   or NIL in the case of a directory pathname.
+A flag that is true iff the unix-style-pathname was just
+   a file-namestring without / path specification.
+ENSURE-DIRECTORY forces the namestring to be interpreted as a directory pathname:
+the third return value will be NIL, and final component of the namestring
+will be treated as part of the directory path.
+
+An empty string is thus read as meaning a pathname object with all fields nil.
+
+Note that colon characters #\: will NOT be interpreted as host specification.
+Absolute pathnames are only appropriate on Unix-style systems.
+
+The intention of this function is to support structured component names,
+e.g., \(:file \"foo/bar\"\), which will be unpacked to relative pathnames."
+    (check-type unix-namestring string)
+    (check-type dot-dot (member nil :back :up))
+    (if (and (not (find #\/ unix-namestring)) (not ensure-directory)
+             (plusp (length unix-namestring)))
+        (values :relative () unix-namestring t)
+        (let* ((components (split-string unix-namestring :separator "/"))
+               (last-comp (car (last components))))
+          (multiple-value-bind (relative components)
+              (if (equal (first components) "")
+                  (if (equal (first-char unix-namestring) #\/)
+                      (values :absolute (cdr components))
+                      (values :relative nil))
+                  (values :relative components))
+            (setf components (remove-if #'(lambda (x) (member x '("" ".") :test #'equal))
+                                        components))
+            (setf components (substitute (or dot-dot :back) ".." components :test #'equal))
+            (cond
+              ((equal last-comp "")
+               (values relative components nil nil)) ; "" already removed from components
+              (ensure-directory
+               (values relative components nil nil))
+              (t
+               (values relative (butlast components) last-comp nil)))))))
+
+  (defun split-name-type (filename)
+    "Split a filename into two values NAME and TYPE that are returned.
+We assume filename has no directory component.
+The last . if any separates name and type from from type,
+except that if there is only one . and it is in first position,
+the whole filename is the NAME with an empty type.
+NAME is always a string.
+For an empty type, *UNSPECIFIC-PATHNAME-TYPE* is returned."
+    (check-type filename string)
+    (assert (plusp (length filename)))
+    (destructuring-bind (name &optional (type *unspecific-pathname-type*))
+        (split-string filename :max 2 :separator ".")
+      (if (equal name "")
+          (values filename *unspecific-pathname-type*)
+          (values name type))))
+
+  (defun parse-unix-namestring (name &rest keys &key type defaults dot-dot ensure-directory
+                                &allow-other-keys)
+    "Coerce NAME into a PATHNAME using standard Unix syntax.
+
+Unix syntax is used whether or not the underlying system is Unix;
+on such non-Unix systems it is reliably usable only for relative pathnames.
+This function is especially useful to manipulate relative pathnames portably,
+where it is crucial to possess a portable pathname syntax independent of the underlying OS.
+This is what PARSE-UNIX-NAMESTRING provides, and why we use it in ASDF.
+
+When given a PATHNAME object, just return it untouched.
+When given NIL, just return NIL.
+When given a non-null SYMBOL, first downcase its name and treat it as a string.
+When given a STRING, portably decompose it into a pathname as below.
+
+#\\/ separates directory components.
+
+The last #\\/-separated substring is interpreted as follows:
+1- If TYPE is :DIRECTORY or ENSURE-DIRECTORY is true,
+ the string is made the last directory component, and NAME and TYPE are NIL.
+ if the string is empty, it's the empty pathname with all slots NIL.
+2- If TYPE is NIL, the substring is a file-namestring, and its NAME and TYPE
+ are separated by SPLIT-NAME-TYPE.
+3- If TYPE is a string, it is the given TYPE, and the whole string is the NAME.
+
+Directory components with an empty name or the name \".\" are removed.
+Any directory named \"..\" is read as DOT-DOT,
+which must be one of :BACK or :UP and defaults to :BACK.
+
+HOST, DEVICE and VERSION components are taken from DEFAULTS,
+which itself defaults to *NIL-PATHNAME*, also used if DEFAULTS is NIL.
+No host or device can be specified in the string itself,
+which makes it unsuitable for absolute pathnames outside Unix.
+
+For relative pathnames, these components (and hence the defaults) won't matter
+if you use MERGE-PATHNAMES* but will matter if you use MERGE-PATHNAMES,
+which is an important reason to always use MERGE-PATHNAMES*.
+
+Arbitrary keys are accepted, and the parse result is passed to ENSURE-PATHNAME
+with those keys, removing TYPE DEFAULTS and DOT-DOT.
+When you're manipulating pathnames that are supposed to make sense portably
+even though the OS may not be Unixish, we recommend you use :WANT-RELATIVE T
+to throw an error if the pathname is absolute"
+    (block nil
+      (check-type type (or null string (eql :directory)))
+      (when ensure-directory
+        (setf type :directory))
+      (etypecase name
+        ((or null pathname) (return name))
+        (symbol
+         (setf name (string-downcase name)))
+        (string))
+      (multiple-value-bind (relative path filename file-only)
+          (split-unix-namestring-directory-components
+           name :dot-dot dot-dot :ensure-directory (eq type :directory))
+        (multiple-value-bind (name type)
+            (cond
+              ((or (eq type :directory) (null filename))
+               (values nil nil))
+              (type
+               (values filename type))
+              (t
+               (split-name-type filename)))
+          (apply 'ensure-pathname
+                 (make-pathname
+                  :directory (unless file-only (cons relative path))
+                  :name name :type type
+                  :defaults (or #-mcl defaults *nil-pathname*))
+                 (remove-plist-keys '(:type :dot-dot :defaults) keys))))))
+
+  (defun unix-namestring (pathname)
+    "Given a non-wild PATHNAME, return a Unix-style namestring for it.
+If the PATHNAME is NIL or a STRING, return it unchanged.
+
+This only considers the DIRECTORY, NAME and TYPE components of the pathname.
+This is a portable solution for representing relative pathnames,
+But unless you are running on a Unix system, it is not a general solution
+to representing native pathnames.
+
+An error is signaled if the argument is not NULL, a STRING or a PATHNAME,
+or if it is a PATHNAME but some of its components are not recognized."
+    (etypecase pathname
+      ((or null string) pathname)
+      (pathname
+       (with-output-to-string (s)
+         (flet ((err () (parameter-error "~S: invalid unix-namestring ~S"
+                                         'unix-namestring pathname)))
+           (let* ((dir (normalize-pathname-directory-component (pathname-directory pathname)))
+                  (name (pathname-name pathname))
+                  (name (and (not (eq name :unspecific)) name))
+                  (type (pathname-type pathname))
+                  (type (and (not (eq type :unspecific)) type)))
+             (cond
+               ((member dir '(nil :unspecific)))
+               ((eq dir '(:relative)) (princ "./" s))
+               ((consp dir)
+                (destructuring-bind (relabs &rest dirs) dir
+                  (or (member relabs '(:relative :absolute)) (err))
+                  (when (eq relabs :absolute) (princ #\/ s))
+                  (loop :for x :in dirs :do
+                    (cond
+                      ((member x '(:back :up)) (princ "../" s))
+                      ((equal x "") (err))
+                      ;;((member x '("." "..") :test 'equal) (err))
+                      ((stringp x) (format s "~A/" x))
+                      (t (err))))))
+               (t (err)))
+             (cond
+               (name
+                (unless (and (stringp name) (or (null type) (stringp type))) (err))
+                (format s "~A~@[.~A~]" name type))
+               (t
+                (or (null type) (err)))))))))))
+
+;;; Absolute and relative pathnames
+(with-upgradability ()
+  (defun subpathname (pathname subpath &key type)
+    "This function takes a PATHNAME and a SUBPATH and a TYPE.
+If SUBPATH is already a PATHNAME object (not namestring),
+and is an absolute pathname at that, it is returned unchanged;
+otherwise, SUBPATH is turned into a relative pathname with given TYPE
+as per PARSE-UNIX-NAMESTRING with :WANT-RELATIVE T :TYPE TYPE,
+then it is merged with the PATHNAME-DIRECTORY-PATHNAME of PATHNAME."
+    (or (and (pathnamep subpath) (absolute-pathname-p subpath))
+        (merge-pathnames* (parse-unix-namestring subpath :type type :want-relative t)
+                          (pathname-directory-pathname pathname))))
+
+  (defun subpathname* (pathname subpath &key type)
+    "returns NIL if the base pathname is NIL, otherwise like SUBPATHNAME."
+    (and pathname
+         (subpathname (ensure-directory-pathname pathname) subpath :type type)))
+
+  (defun pathname-root (pathname)
+    "return the root directory for the host and device of given PATHNAME"
+    (make-pathname :directory '(:absolute)
+                   :name nil :type nil :version nil
+                   :defaults pathname ;; host device, and on scl, *some*
+                   ;; scheme-specific parts: port username password, not others:
+                   . #.(or #+scl '(:parameters nil :query nil :fragment nil))))
+
+  (defun pathname-host-pathname (pathname)
+    "return a pathname with the same host as given PATHNAME, and all other fields NIL"
+    (make-pathname :directory nil
+                   :name nil :type nil :version nil :device nil
+                   :defaults pathname ;; host device, and on scl, *some*
+                   ;; scheme-specific parts: port username password, not others:
+                   . #.(or #+scl '(:parameters nil :query nil :fragment nil))))
+
+  (defun ensure-absolute-pathname (path &optional defaults (on-error 'error))
+    "Given a pathname designator PATH, return an absolute pathname as specified by PATH
+considering the DEFAULTS, or, if not possible, use CALL-FUNCTION on the specified ON-ERROR behavior,
+with a format control-string and other arguments as arguments"
+    (cond
+      ((absolute-pathname-p path))
+      ((stringp path) (ensure-absolute-pathname (pathname path) defaults on-error))
+      ((not (pathnamep path)) (call-function on-error "not a valid pathname designator ~S" path))
+      ((let ((default-pathname (if (pathnamep defaults) defaults (call-function defaults))))
+         (or (if (absolute-pathname-p default-pathname)
+                 (absolute-pathname-p (merge-pathnames* path default-pathname))
+                 (call-function on-error "Default pathname ~S is not an absolute pathname"
+                                default-pathname))
+             (call-function on-error "Failed to merge ~S with ~S into an absolute pathname"
+                            path default-pathname))))
+      (t (call-function on-error
+                        "Cannot ensure ~S is evaluated as an absolute pathname with defaults ~S"
+                        path defaults))))
+
+  (defun subpathp (maybe-subpath base-pathname)
+    "if MAYBE-SUBPATH is a pathname that is under BASE-PATHNAME, return a pathname object that
+when used with MERGE-PATHNAMES* with defaults BASE-PATHNAME, returns MAYBE-SUBPATH."
+    (and (pathnamep maybe-subpath) (pathnamep base-pathname)
+         (absolute-pathname-p maybe-subpath) (absolute-pathname-p base-pathname)
+         (directory-pathname-p base-pathname) (not (wild-pathname-p base-pathname))
+         (pathname-equal (pathname-root maybe-subpath) (pathname-root base-pathname))
+         (with-pathname-defaults (*nil-pathname*)
+           (let ((enough (enough-namestring maybe-subpath base-pathname)))
+             (and (relative-pathname-p enough) (pathname enough))))))
+
+  (defun enough-pathname (maybe-subpath base-pathname)
+    "if MAYBE-SUBPATH is a pathname that is under BASE-PATHNAME, return a pathname object that
+when used with MERGE-PATHNAMES* with defaults BASE-PATHNAME, returns MAYBE-SUBPATH."
+    (let ((sub (when maybe-subpath (pathname maybe-subpath)))
+          (base (when base-pathname (ensure-absolute-pathname (pathname base-pathname)))))
+      (or (and base (subpathp sub base)) sub)))
+
+  (defun call-with-enough-pathname (maybe-subpath defaults-pathname thunk)
+    "In a context where *DEFAULT-PATHNAME-DEFAULTS* is bound to DEFAULTS-PATHNAME (if not null,
+or else to its current value), call THUNK with ENOUGH-PATHNAME for MAYBE-SUBPATH
+given DEFAULTS-PATHNAME as a base pathname."
+    (let ((enough (enough-pathname maybe-subpath defaults-pathname))
+          (*default-pathname-defaults* (or defaults-pathname *default-pathname-defaults*)))
+      (funcall thunk enough)))
+
+  (defmacro with-enough-pathname ((pathname-var &key (pathname pathname-var)
+                                                  (defaults *default-pathname-defaults*))
+                                  &body body)
+    "Shorthand syntax for CALL-WITH-ENOUGH-PATHNAME"
+    `(call-with-enough-pathname ,pathname ,defaults #'(lambda (,pathname-var) ,@body))))
+
+
+;;; Wildcard pathnames
+(with-upgradability ()
+  (defparameter *wild* (or #+cormanlisp "*" :wild)
+    "Wild component for use with MAKE-PATHNAME")
+  (defparameter *wild-directory-component* (or :wild)
+    "Wild directory component for use with MAKE-PATHNAME")
+  (defparameter *wild-inferiors-component* (or :wild-inferiors)
+    "Wild-inferiors directory component for use with MAKE-PATHNAME")
+  (defparameter *wild-file*
+    (make-pathname :directory nil :name *wild* :type *wild*
+                   :version (or #-(or allegro abcl xcl) *wild*))
+    "A pathname object with wildcards for matching any file with TRANSLATE-PATHNAME")
+  (defparameter *wild-file-for-directory*
+    (make-pathname :directory nil :name *wild* :type (or #-(or clisp gcl) *wild*)
+                   :version (or #-(or allegro abcl clisp gcl xcl) *wild*))
+    "A pathname object with wildcards for matching any file with DIRECTORY")
+  (defparameter *wild-directory*
+    (make-pathname :directory `(:relative ,*wild-directory-component*)
+                   :name nil :type nil :version nil)
+    "A pathname object with wildcards for matching any subdirectory")
+  (defparameter *wild-inferiors*
+    (make-pathname :directory `(:relative ,*wild-inferiors-component*)
+                   :name nil :type nil :version nil)
+    "A pathname object with wildcards for matching any recursive subdirectory")
+  (defparameter *wild-path*
+    (merge-pathnames* *wild-file* *wild-inferiors*)
+    "A pathname object with wildcards for matching any file in any recursive subdirectory")
+
+  (defun wilden (path)
+    "From a pathname, return a wildcard pathname matching any file in any subdirectory of given pathname's directory"
+    (merge-pathnames* *wild-path* path)))
+
+
+;;; Translate a pathname
+(with-upgradability ()
+  (defun relativize-directory-component (directory-component)
+    "Given the DIRECTORY-COMPONENT of a pathname, return an otherwise similar relative directory component"
+    (let ((directory (normalize-pathname-directory-component directory-component)))
+      (cond
+        ((stringp directory)
+         (list :relative directory))
+        ((eq (car directory) :absolute)
+         (cons :relative (cdr directory)))
+        (t
+         directory))))
+
+  (defun relativize-pathname-directory (pathspec)
+    "Given a PATHNAME, return a relative pathname with otherwise the same components"
+    (let ((p (pathname pathspec)))
+      (make-pathname
+       :directory (relativize-directory-component (pathname-directory p))
+       :defaults p)))
+
+  (defun directory-separator-for-host (&optional (pathname *default-pathname-defaults*))
+    "Given a PATHNAME, return the character used to delimit directory names on this host and device."
+    (let ((foo (make-pathname :directory '(:absolute "FOO") :defaults pathname)))
+      (last-char (namestring foo))))
+
+  #-scl
+  (defun directorize-pathname-host-device (pathname)
+    "Given a PATHNAME, return a pathname that has representations of its HOST and DEVICE components
+added to its DIRECTORY component. This is useful for output translations."
+    (os-cond
+     ((os-unix-p)
+      (when (physical-pathname-p pathname)
+        (return-from directorize-pathname-host-device pathname))))
+    (let* ((root (pathname-root pathname))
+           (wild-root (wilden root))
+           (absolute-pathname (merge-pathnames* pathname root))
+           (separator (directory-separator-for-host root))
+           (root-namestring (namestring root))
+           (root-string
+             (substitute-if #\/
+                            #'(lambda (x) (or (eql x #\:)
+                                              (eql x separator)))
+                            root-namestring)))
+      (multiple-value-bind (relative path filename)
+          (split-unix-namestring-directory-components root-string :ensure-directory t)
+        (declare (ignore relative filename))
+        (let ((new-base (make-pathname :defaults root :directory `(:absolute ,@path))))
+          (translate-pathname absolute-pathname wild-root (wilden new-base))))))
+
+  #+scl
+  (defun directorize-pathname-host-device (pathname)
+    (let ((scheme (ext:pathname-scheme pathname))
+          (host (pathname-host pathname))
+          (port (ext:pathname-port pathname))
+          (directory (pathname-directory pathname)))
+      (flet ((specificp (x) (and x (not (eq x :unspecific)))))
+        (if (or (specificp port)
+                (and (specificp host) (plusp (length host)))
+                (specificp scheme))
+            (let ((prefix ""))
+              (when (specificp port)
+                (setf prefix (format nil ":~D" port)))
+              (when (and (specificp host) (plusp (length host)))
+                (setf prefix (strcat host prefix)))
+              (setf prefix (strcat ":" prefix))
+              (when (specificp scheme)
+                (setf prefix (strcat scheme prefix)))
+              (assert (and directory (eq (first directory) :absolute)))
+              (make-pathname :directory `(:absolute ,prefix ,@(rest directory))
+                             :defaults pathname)))
+        pathname)))
+
+  (defun translate-pathname* (path absolute-source destination &optional root source)
+    "A wrapper around TRANSLATE-PATHNAME to be used by the ASDF output-translations facility.
+PATH is the pathname to be translated.
+ABSOLUTE-SOURCE is an absolute pathname to use as source for translate-pathname,
+DESTINATION is either a function, to be called with PATH and ABSOLUTE-SOURCE,
+or a relative pathname, to be merged with ROOT and used as destination for translate-pathname
+or an absolute pathname, to be used as destination for translate-pathname.
+In that last case, if ROOT is non-NIL, PATH is first transformated by DIRECTORIZE-PATHNAME-HOST-DEVICE."
+    (declare (ignore source))
+    (cond
+      ((functionp destination)
+       (funcall destination path absolute-source))
+      ((eq destination t)
+       path)
+      ((not (pathnamep destination))
+       (parameter-error "~S: Invalid destination" 'translate-pathname*))
+      ((not (absolute-pathname-p destination))
+       (translate-pathname path absolute-source (merge-pathnames* destination root)))
+      (root
+       (translate-pathname (directorize-pathname-host-device path) absolute-source destination))
+      (t
+       (translate-pathname path absolute-source destination))))
+
+  (defvar *output-translation-function* 'identity
+    "Hook for output translations.
+
+This function needs to be idempotent, so that actions can work
+whether their inputs were translated or not,
+which they will be if we are composing operations. e.g. if some
+create-lisp-op creates a lisp file from some higher-level input,
+you need to still be able to use compile-op on that lisp file."))
+;;;; -------------------------------------------------------------------------
+;;;; Portability layer around Common Lisp filesystem access
+
+(uiop/package:define-package :uiop/filesystem
+  (:use :uiop/common-lisp :uiop/package :uiop/utility :uiop/os :uiop/pathname)
+  (:export
+   ;; Native namestrings
+   #:native-namestring #:parse-native-namestring
+   ;; Probing the filesystem
+   #:truename* #:safe-file-write-date #:probe-file* #:directory-exists-p #:file-exists-p
+   #:directory* #:filter-logical-directory-results #:directory-files #:subdirectories
+   #:collect-sub*directories
+   ;; Resolving symlinks somewhat
+   #:truenamize #:resolve-symlinks #:*resolve-symlinks* #:resolve-symlinks*
+   ;; merging with cwd
+   #:get-pathname-defaults #:call-with-current-directory #:with-current-directory
+   ;; Environment pathnames
+   #:inter-directory-separator #:split-native-pathnames-string
+   #:getenv-pathname #:getenv-pathnames
+   #:getenv-absolute-directory #:getenv-absolute-directories
+   #:lisp-implementation-directory #:lisp-implementation-pathname-p
+   ;; Simple filesystem operations
+   #:ensure-all-directories-exist
+   #:rename-file-overwriting-target
+   #:delete-file-if-exists #:delete-empty-directory #:delete-directory-tree))
+(in-package :uiop/filesystem)
+
+;;; Native namestrings, as seen by the operating system calls rather than Lisp
+(with-upgradability ()
+  (defun native-namestring (x)
+    "From a non-wildcard CL pathname, a return namestring suitable for passing to the operating system"
+    (when x
+      (let ((p (pathname x)))
+        #+clozure (with-pathname-defaults () (ccl:native-translated-namestring p)) ; see ccl bug 978
+        #+(or cmucl scl) (ext:unix-namestring p nil)
+        #+sbcl (sb-ext:native-namestring p)
+        #-(or clozure cmucl sbcl scl)
+        (os-cond
+         ((os-unix-p) (unix-namestring p))
+         (t (namestring p))))))
+
+  (defun parse-native-namestring (string &rest constraints &key ensure-directory &allow-other-keys)
+    "From a native namestring suitable for use by the operating system, return
+a CL pathname satisfying all the specified constraints as per ENSURE-PATHNAME"
+    (check-type string (or string null))
+    (let* ((pathname
+             (when string
+               (with-pathname-defaults ()
+                 #+clozure (ccl:native-to-pathname string)
+                 #+cmucl (uiop/os::parse-unix-namestring* string)
+                 #+sbcl (sb-ext:parse-native-namestring string)
+                 #+scl (lisp::parse-unix-namestring string)
+                 #-(or clozure cmucl sbcl scl)
+                 (os-cond
+                  ((os-unix-p) (parse-unix-namestring string :ensure-directory ensure-directory))
+                  (t (parse-namestring string))))))
+           (pathname
+             (if ensure-directory
+                 (and pathname (ensure-directory-pathname pathname))
+                 pathname)))
+      (apply 'ensure-pathname pathname constraints))))
+
+
+;;; Probing the filesystem
+(with-upgradability ()
+  (defun truename* (p)
+    "Nicer variant of TRUENAME that plays well with NIL, avoids logical pathname contexts, and tries both files and directories"
+    (when p
+      (when (stringp p) (setf p (with-pathname-defaults () (parse-namestring p))))
+      (values
+       (or (ignore-errors (truename p))
+           ;; this is here because trying to find the truename of a directory pathname WITHOUT supplying
+           ;; a trailing directory separator, causes an error on some lisps.
+           #+(or clisp gcl) (if-let (d (ensure-directory-pathname p nil)) (ignore-errors (truename d)))
+           ;; On Genera, truename of a directory pathname will probably fail as Genera
+           ;; will merge in a filename/type/version from *default-pathname-defaults* and
+           ;; will try to get the truename of a file that probably doesn't exist.
+           #+genera (when (directory-pathname-p p)
+                      (let ((d (scl:send p :directory-pathname-as-file)))
+                        (ensure-directory-pathname (ignore-errors (truename d)) nil)))))))
+
+  (defun safe-file-write-date (pathname)
+    "Safe variant of FILE-WRITE-DATE that may return NIL rather than raise an error."
+    ;; If FILE-WRITE-DATE returns NIL, it's possible that
+    ;; the user or some other agent has deleted an input file.
+    ;; Also, generated files will not exist at the time planning is done
+    ;; and calls compute-action-stamp which calls safe-file-write-date.
+    ;; So it is very possible that we can't get a valid file-write-date,
+    ;; and we can survive and we will continue the planning
+    ;; as if the file were very old.
+    ;; (or should we treat the case in a different, special way?)
+    (and pathname
+         (handler-case (file-write-date (physicalize-pathname pathname))
+           (file-error () nil))))
+
+  (defun probe-file* (p &key truename)
+    "when given a pathname P (designated by a string as per PARSE-NAMESTRING),
+probes the filesystem for a file or directory with given pathname.
+If it exists, return its truename if TRUENAME is true,
+or the original (parsed) pathname if it is false (the default)."
+    (values
+     (ignore-errors
+      (setf p (funcall 'ensure-pathname p
+                       :namestring :lisp
+                       :ensure-physical t
+                       :ensure-absolute t :defaults 'get-pathname-defaults
+                       :want-non-wild t
+                       :on-error nil))
+      (when p
+        #+allegro
+        (probe-file p :follow-symlinks truename)
+        #+gcl
+        (if truename
+            (truename* p)
+            (let ((kind (car (si::stat p))))
+              (when (eq kind :link)
+                (setf kind (ignore-errors (car (si::stat (truename* p))))))
+              (ecase kind
+                ((nil) nil)
+                ((:file :link)
+                 (cond
+                   ((file-pathname-p p) p)
+                   ((directory-pathname-p p)
+                    (subpathname p (car (last (pathname-directory p)))))))
+                (:directory (ensure-directory-pathname p)))))
+        #+clisp
+        #.(let* ((fs (or #-os-windows (find-symbol* '#:file-stat :posix nil)))
+                 (pp (find-symbol* '#:probe-pathname :ext nil)))
+            `(if truename
+                 ,(if pp
+                      `(values (,pp p))
+                      '(or (truename* p)
+                        (truename* (ignore-errors (ensure-directory-pathname p)))))
+                 ,(cond
+                    (fs `(and (,fs p) p))
+                    (pp `(nth-value 1 (,pp p)))
+                    (t '(or (and (truename* p) p)
+                         (if-let (d (ensure-directory-pathname p))
+                          (and (truename* d) d)))))))
+        #-(or allegro clisp gcl)
+        (if truename
+            (probe-file p)
+            (and
+             #+(or cmucl scl) (unix:unix-stat (ext:unix-namestring p))
+             #+(and lispworks os-unix) (system:get-file-stat p)
+             #+sbcl (sb-unix:unix-stat (sb-ext:native-namestring p))
+             #-(or cmucl (and lispworks os-unix) sbcl scl) (file-write-date p)
+             p))))))
+
+  (defun directory-exists-p (x)
+    "Is X the name of a directory that exists on the filesystem?"
+    #+allegro
+    (excl:probe-directory x)
+    #+clisp
+    (handler-case (ext:probe-directory x)
+           (sys::simple-file-error ()
+             nil))
+    #-(or allegro clisp)
+    (let ((p (probe-file* x :truename t)))
+      (and (directory-pathname-p p) p)))
+
+  (defun file-exists-p (x)
+    "Is X the name of a file that exists on the filesystem?"
+    (let ((p (probe-file* x :truename t)))
+      (and (file-pathname-p p) p)))
+
+  (defun directory* (pathname-spec &rest keys &key &allow-other-keys)
+    "Return a list of the entries in a directory by calling DIRECTORY.
+Try to override the defaults to not resolving symlinks, if implementation allows."
+    (apply 'directory pathname-spec
+           (append keys '#.(or #+allegro '(:directories-are-files nil :follow-symbolic-links nil)
+                               #+(or clozure digitool) '(:follow-links nil)
+                               #+clisp '(:circle t :if-does-not-exist :ignore)
+                               #+(or cmucl scl) '(:follow-links nil :truenamep nil)
+                               #+lispworks '(:link-transparency nil)
+                               #+sbcl (when (find-symbol* :resolve-symlinks '#:sb-impl nil)
+                                        '(:resolve-symlinks nil))))))
+
+  (defun filter-logical-directory-results (directory entries merger)
+    "If DIRECTORY isn't a logical pathname, return ENTRIES. If it is,
+given ENTRIES in the DIRECTORY, remove the entries which are physical yet
+when transformed by MERGER have a different TRUENAME.
+Also remove duplicates as may appear with some translation rules.
+This function is used as a helper to DIRECTORY-FILES to avoid invalid entries
+when using logical-pathnames."
+    (if (logical-pathname-p directory)
+        (remove-duplicates ;; on CLISP, querying ~/ will return duplicates
+         ;; Try hard to not resolve logical-pathname into physical pathnames;
+         ;; otherwise logical-pathname users/lovers will be disappointed.
+         ;; If directory* could use some implementation-dependent magic,
+         ;; we will have logical pathnames already; otherwise,
+         ;; we only keep pathnames for which specifying the name and
+         ;; translating the LPN commute.
+         (loop :for f :in entries
+               :for p = (or (and (logical-pathname-p f) f)
+                            (let* ((u (ignore-errors (call-function merger f))))
+                              ;; The first u avoids a cumbersome (truename u) error.
+                              ;; At this point f should already be a truename,
+                              ;; but isn't quite in CLISP, for it doesn't have :version :newest
+                              (and u (equal (truename* u) (truename* f)) u)))
+           :when p :collect p)
+         :test 'pathname-equal)
+        entries))
+
+  (defun directory-files (directory &optional (pattern *wild-file-for-directory*))
+    "Return a list of the files in a directory according to the PATTERN.
+Subdirectories should NOT be returned.
+  PATTERN defaults to a pattern carefully chosen based on the implementation;
+override the default at your own risk.
+  DIRECTORY-FILES tries NOT to resolve symlinks if the implementation permits this,
+but the behavior in presence of symlinks is not portable. Use IOlib to handle such situations."
+    (let ((dir (ensure-directory-pathname directory)))
+      (when (logical-pathname-p dir)
+        ;; Because of the filtering we do below,
+        ;; logical pathnames have restrictions on wild patterns.
+        ;; Not that the results are very portable when you use these patterns on physical pathnames.
+        (when (wild-pathname-p dir)
+          (parameter-error "~S: Invalid wild pattern in logical directory ~S"
+                           'directory-files directory))
+        (unless (member (pathname-directory pattern) '(() (:relative)) :test 'equal)
+          (parameter-error "~S: Invalid file pattern ~S for logical directory ~S" 'directory-files pattern directory))
+        (setf pattern (make-pathname-logical pattern (pathname-host dir))))
+      (let* ((pat (merge-pathnames* pattern dir))
+             (entries (ignore-errors (directory* pat))))
+        (remove-if 'directory-pathname-p
+                   (filter-logical-directory-results
+                    directory entries
+                    #'(lambda (f)
+                        (make-pathname :defaults dir
+                                       :name (make-pathname-component-logical (pathname-name f))
+                                       :type (make-pathname-component-logical (pathname-type f))
+                                       :version (make-pathname-component-logical (pathname-version f)))))))))
+
+  (defun subdirectories (directory)
+    "Given a DIRECTORY pathname designator, return a list of the subdirectories under it.
+The behavior in presence of symlinks is not portable. Use IOlib to handle such situations."
+    (let* ((directory (ensure-directory-pathname directory))
+           #-(or abcl cormanlisp genera xcl)
+           (wild (merge-pathnames*
+                  #-(or abcl allegro cmucl lispworks sbcl scl xcl)
+                  *wild-directory*
+                  #+(or abcl allegro cmucl lispworks sbcl scl xcl) "*.*"
+                  directory))
+           (dirs
+             #-(or abcl cormanlisp genera xcl)
+             (ignore-errors
+              (directory* wild . #.(or #+clozure '(:directories t :files nil)
+                                       #+mcl '(:directories t))))
+             #+(or abcl xcl) (system:list-directory directory)
+             #+cormanlisp (cl::directory-subdirs directory)
+             #+genera (handler-case (fs:directory-list directory) (fs:directory-not-found () nil)))
+           #+(or abcl allegro cmucl genera lispworks sbcl scl xcl)
+           (dirs (loop :for x :in dirs
+                       :for d = #+(or abcl xcl) (extensions:probe-directory x)
+                       #+allegro (excl:probe-directory x)
+                       #+(or cmucl sbcl scl) (directory-pathname-p x)
+                       #+genera (getf (cdr x) :directory)
+                       #+lispworks (lw:file-directory-p x)
+                       :when d :collect #+(or abcl allegro xcl) (ensure-directory-pathname d)
+                         #+genera (ensure-directory-pathname (first x))
+                       #+(or cmucl lispworks sbcl scl) x)))
+      (filter-logical-directory-results
+       directory dirs
+       (let ((prefix (or (normalize-pathname-directory-component (pathname-directory directory))
+                         '(:absolute)))) ; because allegro returns NIL for #p"FOO:"
+         #'(lambda (d)
+             (let ((dir (normalize-pathname-directory-component (pathname-directory d))))
+               (and (consp dir) (consp (cdr dir))
+                    (make-pathname
+                     :defaults directory :name nil :type nil :version nil
+                     :directory (append prefix (make-pathname-component-logical (last dir)))))))))))
+
+  (defun collect-sub*directories (directory collectp recursep collector)
+    "Given a DIRECTORY, when COLLECTP returns true when CALL-FUNCTION'ed with the directory,
+call-function the COLLECTOR function designator on the directory,
+and recurse each of its subdirectories on which the RECURSEP returns true when CALL-FUNCTION'ed with them.
+This function will thus let you traverse a filesystem hierarchy,
+superseding the functionality of CL-FAD:WALK-DIRECTORY.
+The behavior in presence of symlinks is not portable. Use IOlib to handle such situations."
+    (when (call-function collectp directory)
+      (call-function collector directory)
+      (dolist (subdir (subdirectories directory))
+        (when (call-function recursep subdir)
+          (collect-sub*directories subdir collectp recursep collector))))))
+
+;;; Resolving symlinks somewhat
+(with-upgradability ()
+  (defun truenamize (pathname)
+    "Resolve as much of a pathname as possible"
+    (block nil
+      (when (typep pathname '(or null logical-pathname)) (return pathname))
+      (let ((p pathname))
+        (unless (absolute-pathname-p p)
+          (setf p (or (absolute-pathname-p (ensure-absolute-pathname p 'get-pathname-defaults nil))
+                      (return p))))
+        (when (logical-pathname-p p) (return p))
+        (let ((found (probe-file* p :truename t)))
+          (when found (return found)))
+        (let* ((directory (normalize-pathname-directory-component (pathname-directory p)))
+               (up-components (reverse (rest directory)))
+               (down-components ()))
+          (assert (eq :absolute (first directory)))
+          (loop :while up-components :do
+            (if-let (parent
+                     (ignore-errors
+                      (probe-file* (make-pathname :directory `(:absolute ,@(reverse up-components))
+                                                  :name nil :type nil :version nil :defaults p))))
+              (if-let (simplified
+                       (ignore-errors
+                        (merge-pathnames*
+                         (make-pathname :directory `(:relative ,@down-components)
+                                        :defaults p)
+                         (ensure-directory-pathname parent))))
+                (return simplified)))
+            (push (pop up-components) down-components)
+            :finally (return p))))))
+
+  (defun resolve-symlinks (path)
+    "Do a best effort at resolving symlinks in PATH, returning a partially or totally resolved PATH."
+    #-allegro (truenamize path)
+    #+allegro
+    (if (physical-pathname-p path)
+        (or (ignore-errors (excl:pathname-resolve-symbolic-links path)) path)
+        path))
+
+  (defvar *resolve-symlinks* t
+    "Determine whether or not ASDF resolves symlinks when defining systems.
+Defaults to T.")
+
+  (defun resolve-symlinks* (path)
+    "RESOLVE-SYMLINKS in PATH iff *RESOLVE-SYMLINKS* is T (the default)."
+    (if *resolve-symlinks*
+        (and path (resolve-symlinks path))
+        path)))
+
+
+;;; Check pathname constraints
+(with-upgradability ()
+  (defun ensure-pathname
+      (pathname &key
+                  on-error
+                  defaults type dot-dot namestring
+                  empty-is-nil
+                  want-pathname
+                  want-logical want-physical ensure-physical
+                  want-relative want-absolute ensure-absolute ensure-subpath
+                  want-non-wild want-wild wilden
+                  want-file want-directory ensure-directory
+                  want-existing ensure-directories-exist
+                  truename resolve-symlinks truenamize
+       &aux (p pathname)) ;; mutable working copy, preserve original
+    "Coerces its argument into a PATHNAME,
+optionally doing some transformations and checking specified constraints.
+
+If the argument is NIL, then NIL is returned unless the WANT-PATHNAME constraint is specified.
+
+If the argument is a STRING, it is first converted to a pathname via
+PARSE-UNIX-NAMESTRING, PARSE-NAMESTRING or PARSE-NATIVE-NAMESTRING respectively
+depending on the NAMESTRING argument being :UNIX, :LISP or :NATIVE respectively,
+or else by using CALL-FUNCTION on the NAMESTRING argument;
+if :UNIX is specified (or NIL, the default, which specifies the same thing),
+then PARSE-UNIX-NAMESTRING it is called with the keywords
+DEFAULTS TYPE DOT-DOT ENSURE-DIRECTORY WANT-RELATIVE, and
+the result is optionally merged into the DEFAULTS if ENSURE-ABSOLUTE is true.
+
+The pathname passed or resulting from parsing the string
+is then subjected to all the checks and transformations below are run.
+
+Each non-nil constraint argument can be one of the symbols T, ERROR, CERROR or IGNORE.
+The boolean T is an alias for ERROR.
+ERROR means that an error will be raised if the constraint is not satisfied.
+CERROR means that an continuable error will be raised if the constraint is not satisfied.
+IGNORE means just return NIL instead of the pathname.
+
+The ON-ERROR argument, if not NIL, is a function designator (as per CALL-FUNCTION)
+that will be called with the the following arguments:
+a generic format string for ensure pathname, the pathname,
+the keyword argument corresponding to the failed check or transformation,
+a format string for the reason ENSURE-PATHNAME failed,
+and a list with arguments to that format string.
+If ON-ERROR is NIL, ERROR is used instead, which does the right thing.
+You could also pass (CERROR \"CONTINUE DESPITE FAILED CHECK\").
+
+The transformations and constraint checks are done in this order,
+which is also the order in the lambda-list:
+
+EMPTY-IS-NIL returns NIL if the argument is an empty string.
+WANT-PATHNAME checks that pathname (after parsing if needed) is not null.
+Otherwise, if the pathname is NIL, ensure-pathname returns NIL.
+WANT-LOGICAL checks that pathname is a LOGICAL-PATHNAME
+WANT-PHYSICAL checks that pathname is not a LOGICAL-PATHNAME
+ENSURE-PHYSICAL ensures that pathname is physical via TRANSLATE-LOGICAL-PATHNAME
+WANT-RELATIVE checks that pathname has a relative directory component
+WANT-ABSOLUTE checks that pathname does have an absolute directory component
+ENSURE-ABSOLUTE merges with the DEFAULTS, then checks again
+that the result absolute is an absolute pathname indeed.
+ENSURE-SUBPATH checks that the pathname is a subpath of the DEFAULTS.
+WANT-FILE checks that pathname has a non-nil FILE component
+WANT-DIRECTORY checks that pathname has nil FILE and TYPE components
+ENSURE-DIRECTORY uses ENSURE-DIRECTORY-PATHNAME to interpret
+any file and type components as being actually a last directory component.
+WANT-NON-WILD checks that pathname is not a wild pathname
+WANT-WILD checks that pathname is a wild pathname
+WILDEN merges the pathname with **/*.*.* if it is not wild
+WANT-EXISTING checks that a file (or directory) exists with that pathname.
+ENSURE-DIRECTORIES-EXIST creates any parent directory with ENSURE-DIRECTORIES-EXIST.
+TRUENAME replaces the pathname by its truename, or errors if not possible.
+RESOLVE-SYMLINKS replaces the pathname by a variant with symlinks resolved by RESOLVE-SYMLINKS.
+TRUENAMIZE uses TRUENAMIZE to resolve as many symlinks as possible."
+    (block nil
+      (flet ((report-error (keyword description &rest arguments)
+               (call-function (or on-error 'error)
+                              "Invalid pathname ~S: ~*~?"
+                              pathname keyword description arguments)))
+        (macrolet ((err (constraint &rest arguments)
+                     `(report-error ',(intern* constraint :keyword) ,@arguments))
+                   (check (constraint condition &rest arguments)
+                     `(when ,constraint
+                        (unless ,condition (err ,constraint ,@arguments))))
+                   (transform (transform condition expr)
+                     `(when ,transform
+                        (,@(if condition `(when ,condition) '(progn))
+                         (setf p ,expr)))))
+          (etypecase p
+            ((or null pathname))
+            (string
+             (when (and (emptyp p) empty-is-nil)
+               (return-from ensure-pathname nil))
+             (setf p (case namestring
+                       ((:unix nil)
+                        (parse-unix-namestring
+                         p :defaults defaults :type type :dot-dot dot-dot
+                           :ensure-directory ensure-directory :want-relative want-relative))
+                       ((:native)
+                        (parse-native-namestring p))
+                       ((:lisp)
+                        (parse-namestring p))
+                       (t
+                        (call-function namestring p))))))
+          (etypecase p
+            (pathname)
+            (null
+             (check want-pathname (pathnamep p) "Expected a pathname, not NIL")
+             (return nil)))
+          (check want-logical (logical-pathname-p p) "Expected a logical pathname")
+          (check want-physical (physical-pathname-p p) "Expected a physical pathname")
+          (transform ensure-physical () (physicalize-pathname p))
+          (check ensure-physical (physical-pathname-p p) "Could not translate to a physical pathname")
+          (check want-relative (relative-pathname-p p) "Expected a relative pathname")
+          (check want-absolute (absolute-pathname-p p) "Expected an absolute pathname")
+          (transform ensure-absolute (not (absolute-pathname-p p))
+                     (ensure-absolute-pathname p defaults (list #'report-error :ensure-absolute "~@?")))
+          (check ensure-absolute (absolute-pathname-p p)
+                 "Could not make into an absolute pathname even after merging with ~S" defaults)
+          (check ensure-subpath (absolute-pathname-p defaults)
+                 "cannot be checked to be a subpath of non-absolute pathname ~S" defaults)
+          (check ensure-subpath (subpathp p defaults) "is not a sub pathname of ~S" defaults)
+          (check want-file (file-pathname-p p) "Expected a file pathname")
+          (check want-directory (directory-pathname-p p) "Expected a directory pathname")
+          (transform ensure-directory (not (directory-pathname-p p)) (ensure-directory-pathname p))
+          (check want-non-wild (not (wild-pathname-p p)) "Expected a non-wildcard pathname")
+          (check want-wild (wild-pathname-p p) "Expected a wildcard pathname")
+          (transform wilden (not (wild-pathname-p p)) (wilden p))
+          (when want-existing
+            (let ((existing (probe-file* p :truename truename)))
+              (if existing
+                  (when truename
+                    (return existing))
+                  (err want-existing "Expected an existing pathname"))))
+          (when ensure-directories-exist (ensure-directories-exist p))
+          (when truename
+            (let ((truename (truename* p)))
+              (if truename
+                  (return truename)
+                  (err truename "Can't get a truename for pathname"))))
+          (transform resolve-symlinks () (resolve-symlinks p))
+          (transform truenamize () (truenamize p))
+          p)))))
+
+
+;;; Pathname defaults
+(with-upgradability ()
+  (defun get-pathname-defaults (&optional (defaults *default-pathname-defaults*))
+    "Find the actual DEFAULTS to use for pathnames, including
+resolving them with respect to GETCWD if the DEFAULTS were relative"
+    (or (absolute-pathname-p defaults)
+        (merge-pathnames* defaults (getcwd))))
+
+  (defun call-with-current-directory (dir thunk)
+    "call the THUNK in a context where the current directory was changed to DIR, if not NIL.
+Note that this operation is usually NOT thread-safe."
+    (if dir
+        (let* ((dir (resolve-symlinks*
+                     (get-pathname-defaults
+                      (ensure-directory-pathname
+                       dir))))
+               (cwd (getcwd))
+               (*default-pathname-defaults* dir))
+          (chdir dir)
+          (unwind-protect
+               (funcall thunk)
+            (chdir cwd)))
+        (funcall thunk)))
+
+  (defmacro with-current-directory ((&optional dir) &body body)
+    "Call BODY while the POSIX current working directory is set to DIR"
+    `(call-with-current-directory ,dir #'(lambda () ,@body))))
+
+
+;;; Environment pathnames
+(with-upgradability ()
+  (defun inter-directory-separator ()
+    "What character does the current OS conventionally uses to separate directories?"
+    (os-cond ((os-unix-p) #\:) (t #\;)))
+
+  (defun split-native-pathnames-string (string &rest constraints &key &allow-other-keys)
+    "Given a string of pathnames specified in native OS syntax, separate them in a list,
+check constraints and normalize each one as per ENSURE-PATHNAME,
+where an empty string denotes NIL."
+    (loop :for namestring :in (split-string string :separator (string (inter-directory-separator)))
+          :collect (unless (emptyp namestring) (apply 'parse-native-namestring namestring constraints))))
+
+  (defun getenv-pathname (x &rest constraints &key ensure-directory want-directory on-error &allow-other-keys)
+    "Extract a pathname from a user-configured environment variable, as per native OS,
+check constraints and normalize as per ENSURE-PATHNAME."
+    ;; For backward compatibility with ASDF 2, want-directory implies ensure-directory
+    (apply 'parse-native-namestring (getenvp x)
+           :ensure-directory (or ensure-directory want-directory)
+           :on-error (or on-error
+                         `(error "In (~S ~S), invalid pathname ~*~S: ~*~?" getenv-pathname ,x))
+           constraints))
+  (defun getenv-pathnames (x &rest constraints &key on-error &allow-other-keys)
+    "Extract a list of pathname from a user-configured environment variable, as per native OS,
+check constraints and normalize each one as per ENSURE-PATHNAME.
+       Any empty entries in the environment variable X will be returned as NILs."
+    (unless (getf constraints :empty-is-nil t)
+      (parameter-error "Cannot have EMPTY-IS-NIL false for ~S" 'getenv-pathnames))
+    (apply 'split-native-pathnames-string (getenvp x)
+           :on-error (or on-error
+                         `(error "In (~S ~S), invalid pathname ~*~S: ~*~?" getenv-pathnames ,x))
+           :empty-is-nil t
+           constraints))
+  (defun getenv-absolute-directory (x)
+    "Extract an absolute directory pathname from a user-configured environment variable,
+as per native OS"
+    (getenv-pathname x :want-absolute t :ensure-directory t))
+  (defun getenv-absolute-directories (x)
+    "Extract a list of absolute directories from a user-configured environment variable,
+as per native OS.  Any empty entries in the environment variable X will be returned as
+NILs."
+    (getenv-pathnames x :want-absolute t :ensure-directory t))
+
+  (defun lisp-implementation-directory (&key truename)
+    "Where are the system files of the current installation of the CL implementation?"
+    (declare (ignorable truename))
+    (let ((dir
+            #+abcl extensions:*lisp-home*
+            #+(or allegro clasp ecl mkcl) #p"SYS:"
+            #+clisp custom:*lib-directory*
+            #+clozure #p"ccl:"
+            #+cmucl (ignore-errors (pathname-parent-directory-pathname (truename #p"modules:")))
+            #+gcl system::*system-directory*
+            #+lispworks lispworks:*lispworks-directory*
+            #+sbcl (if-let (it (find-symbol* :sbcl-homedir-pathname :sb-int nil))
+                     (funcall it)
+                     (getenv-pathname "SBCL_HOME" :ensure-directory t))
+            #+scl (ignore-errors (pathname-parent-directory-pathname (truename #p"file://modules/")))
+            #+xcl ext:*xcl-home*))
+      (if (and dir truename)
+          (truename* dir)
+          dir)))
+
+  (defun lisp-implementation-pathname-p (pathname)
+    "Is the PATHNAME under the current installation of the CL implementation?"
+    ;; Other builtin systems are those under the implementation directory
+    (and (when pathname
+           (if-let (impdir (lisp-implementation-directory))
+             (or (subpathp pathname impdir)
+                 (when *resolve-symlinks*
+                   (if-let (truename (truename* pathname))
+                     (if-let (trueimpdir (truename* impdir))
+                       (subpathp truename trueimpdir)))))))
+         t)))
+
+
+;;; Simple filesystem operations
+(with-upgradability ()
+  (defun ensure-all-directories-exist (pathnames)
+    "Ensure that for every pathname in PATHNAMES, we ensure its directories exist"
+    (dolist (pathname pathnames)
+      (when pathname
+        (ensure-directories-exist (physicalize-pathname pathname)))))
+
+  (defun delete-file-if-exists (x)
+    "Delete a file X if it already exists"
+    (when x (handler-case (delete-file x) (file-error () nil))))
+
+  (defun rename-file-overwriting-target (source target)
+    "Rename a file, overwriting any previous file with the TARGET name,
+in an atomic way if the implementation allows."
+    (let ((source (ensure-pathname source :namestring :lisp :ensure-physical t :want-file t))
+          (target (ensure-pathname target :namestring :lisp :ensure-physical t :want-file t)))
+      #+clisp ;; in recent enough versions of CLISP, :if-exists :overwrite would make it atomic
+      (progn (funcall 'require "syscalls")
+             (symbol-call :posix :copy-file source target :method :rename))
+      #+(and sbcl os-windows) (delete-file-if-exists target) ;; not atomic
+      #-clisp
+      (rename-file source target
+                   #+(or clasp clozure ecl) :if-exists
+                   #+clozure :rename-and-delete #+(or clasp ecl) t)))
+
+  (defun delete-empty-directory (directory-pathname)
+    "Delete an empty directory"
+    #+(or abcl digitool gcl) (delete-file directory-pathname)
+    #+allegro (excl:delete-directory directory-pathname)
+    #+clisp (ext:delete-directory directory-pathname)
+    #+clozure (ccl::delete-empty-directory directory-pathname)
+    #+(or cmucl scl) (multiple-value-bind (ok errno)
+                       (unix:unix-rmdir (native-namestring directory-pathname))
+                     (unless ok
+                       #+cmucl (error "Error number ~A when trying to delete directory ~A"
+                                    errno directory-pathname)
+                       #+scl (error "~@<Error deleting ~S: ~A~@:>"
+                                    directory-pathname (unix:get-unix-error-msg errno))))
+    #+cormanlisp (win32:delete-directory directory-pathname)
+    #+(or clasp ecl) (si:rmdir directory-pathname)
+    #+genera (fs:delete-directory directory-pathname)
+    #+lispworks (lw:delete-directory directory-pathname)
+    #+mkcl (mkcl:rmdir directory-pathname)
+    #+sbcl #.(if-let (dd (find-symbol* :delete-directory :sb-ext nil))
+               `(,dd directory-pathname) ;; requires SBCL 1.0.44 or later
+               `(progn (require :sb-posix) (symbol-call :sb-posix :rmdir directory-pathname)))
+    #+xcl (symbol-call :uiop :run-program `("rmdir" ,(native-namestring directory-pathname)))
+    #-(or abcl allegro clasp clisp clozure cmucl cormanlisp digitool ecl gcl genera lispworks mkcl sbcl scl xcl)
+    (not-implemented-error 'delete-empty-directory "(on your platform)")) ; genera
+
+  (defun delete-directory-tree (directory-pathname &key (validate nil validatep) (if-does-not-exist :error))
+    "Delete a directory including all its recursive contents, aka rm -rf.
+
+To reduce the risk of infortunate mistakes, DIRECTORY-PATHNAME must be
+a physical non-wildcard directory pathname (not namestring).
+
+If the directory does not exist, the IF-DOES-NOT-EXIST argument specifies what happens:
+if it is :ERROR (the default), an error is signaled, whereas if it is :IGNORE, nothing is done.
+
+Furthermore, before any deletion is attempted, the DIRECTORY-PATHNAME must pass
+the validation function designated (as per ENSURE-FUNCTION) by the VALIDATE keyword argument
+which in practice is thus compulsory, and validates by returning a non-NIL result.
+If you're suicidal or extremely confident, just use :VALIDATE T."
+    (check-type if-does-not-exist (member :error :ignore))
+    (setf directory-pathname (ensure-pathname directory-pathname
+                                              :want-pathname t :want-non-wild t
+                                              :want-physical t :want-directory t))
+    (cond
+      ((not validatep)
+       (parameter-error "~S was asked to delete ~S but was not provided a validation predicate"
+              'delete-directory-tree directory-pathname))
+      ((not (call-function validate directory-pathname))
+       (parameter-error "~S was asked to delete ~S but it is not valid ~@[according to ~S~]"
+              'delete-directory-tree directory-pathname validate))
+      ((not (directory-exists-p directory-pathname))
+       (ecase if-does-not-exist
+         (:error
+          (error "~S was asked to delete ~S but the directory does not exist"
+              'delete-directory-tree directory-pathname))
+         (:ignore nil)))
+      #-(or allegro cmucl clozure genera sbcl scl)
+      ((os-unix-p) ;; On Unix, don't recursively walk the directory and delete everything in Lisp,
+       ;; except on implementations where we can prevent DIRECTORY from following symlinks;
+       ;; instead spawn a standard external program to do the dirty work.
+       (symbol-call :uiop :run-program `("rm" "-rf" ,(native-namestring directory-pathname))))
+      (t
+       ;; On supported implementation, call supported system functions
+       #+allegro (symbol-call :excl.osi :delete-directory-and-files
+                              directory-pathname :if-does-not-exist if-does-not-exist)
+       #+clozure (ccl:delete-directory directory-pathname)
+       #+genera (fs:delete-directory directory-pathname :confirm nil)
+       #+sbcl #.(if-let (dd (find-symbol* :delete-directory :sb-ext nil))
+                  `(,dd directory-pathname :recursive t) ;; requires SBCL 1.0.44 or later
+                  '(error "~S requires SBCL 1.0.44 or later" 'delete-directory-tree))
+       ;; Outside Unix or on CMUCL and SCL that can avoid following symlinks,
+       ;; do things the hard way.
+       #-(or allegro clozure genera sbcl)
+       (let ((sub*directories
+               (while-collecting (c)
+                 (collect-sub*directories directory-pathname t t #'c))))
+             (dolist (d (nreverse sub*directories))
+               (map () 'delete-file (directory-files d))
+               (delete-empty-directory d)))))))
+;;;; ---------------------------------------------------------------------------
+;;;; Utilities related to streams
+
+(uiop/package:define-package :uiop/stream
+  (:use :uiop/common-lisp :uiop/package :uiop/utility :uiop/os :uiop/pathname :uiop/filesystem)
+  (:export
+   #:*default-stream-element-type*
+   #:*stdin* #:setup-stdin #:*stdout* #:setup-stdout #:*stderr* #:setup-stderr
+   #:detect-encoding #:*encoding-detection-hook* #:always-default-encoding
+   #:encoding-external-format #:*encoding-external-format-hook* #:default-encoding-external-format
+   #:*default-encoding* #:*utf-8-external-format*
+   #:with-safe-io-syntax #:call-with-safe-io-syntax #:safe-read-from-string
+   #:with-output #:output-string #:with-input #:input-string
+   #:with-input-file #:call-with-input-file #:with-output-file #:call-with-output-file
+   #:null-device-pathname #:call-with-null-input #:with-null-input
+   #:call-with-null-output #:with-null-output
+   #:finish-outputs #:format! #:safe-format!
+   #:copy-stream-to-stream #:concatenate-files #:copy-file
+   #:slurp-stream-string #:slurp-stream-lines #:slurp-stream-line
+   #:slurp-stream-forms #:slurp-stream-form
+   #:read-file-string #:read-file-line #:read-file-lines #:safe-read-file-line
+   #:read-file-forms #:read-file-form #:safe-read-file-form
+   #:eval-input #:eval-thunk #:standard-eval-thunk
+   #:println #:writeln
+   #:file-stream-p #:file-or-synonym-stream-p
+   ;; Temporary files
+   #:*temporary-directory* #:temporary-directory #:default-temporary-directory
+   #:setup-temporary-directory
+   #:call-with-temporary-file #:with-temporary-file
+   #:add-pathname-suffix #:tmpize-pathname
+   #:call-with-staging-pathname #:with-staging-pathname))
+(in-package :uiop/stream)
+
+(with-upgradability ()
+  (defvar *default-stream-element-type*
+    (or #+(or abcl cmucl cormanlisp scl xcl) 'character
+        #+lispworks 'lw:simple-char
+        :default)
+    "default element-type for open (depends on the current CL implementation)")
+
+  (defvar *stdin* *standard-input*
+    "the original standard input stream at startup")
+
+  (defun setup-stdin ()
+    (setf *stdin*
+          #.(or #+clozure 'ccl::*stdin*
+                #+(or cmucl scl) 'system:*stdin*
+                #+(or clasp ecl) 'ext::+process-standard-input+
+                #+sbcl 'sb-sys:*stdin*
+                '*standard-input*)))
+
+  (defvar *stdout* *standard-output*
+    "the original standard output stream at startup")
+
+  (defun setup-stdout ()
+    (setf *stdout*
+          #.(or #+clozure 'ccl::*stdout*
+                #+(or cmucl scl) 'system:*stdout*
+                #+(or clasp ecl) 'ext::+process-standard-output+
+                #+sbcl 'sb-sys:*stdout*
+                '*standard-output*)))
+
+  (defvar *stderr* *error-output*
+    "the original error output stream at startup")
+
+  (defun setup-stderr ()
+    (setf *stderr*
+          #.(or #+allegro 'excl::*stderr*
+                #+clozure 'ccl::*stderr*
+                #+(or cmucl scl) 'system:*stderr*
+                #+(or clasp ecl) 'ext::+process-error-output+
+                #+sbcl 'sb-sys:*stderr*
+                '*error-output*)))
+
+  ;; Run them now. In image.lisp, we'll register them to be run at image restart.
+  (setup-stdin) (setup-stdout) (setup-stderr))
+
+
+;;; Encodings (mostly hooks only; full support requires asdf-encodings)
+(with-upgradability ()
+  (defparameter *default-encoding*
+    ;; preserve explicit user changes to something other than the legacy default :default
+    (or (if-let (previous (and (boundp '*default-encoding*) (symbol-value '*default-encoding*)))
+          (unless (eq previous :default) previous))
+        :utf-8)
+    "Default encoding for source files.
+The default value :utf-8 is the portable thing.
+The legacy behavior was :default.
+If you (asdf:load-system :asdf-encodings) then
+you will have autodetection via *encoding-detection-hook* below,
+reading emacs-style -*- coding: utf-8 -*- specifications,
+and falling back to utf-8 or latin1 if nothing is specified.")
+
+  (defparameter *utf-8-external-format*
+    (if (featurep :asdf-unicode)
+        (or #+clisp charset:utf-8 :utf-8)
+        :default)
+    "Default :external-format argument to pass to CL:OPEN and also
+CL:LOAD or CL:COMPILE-FILE to best process a UTF-8 encoded file.
+On modern implementations, this will decode UTF-8 code points as CL characters.
+On legacy implementations, it may fall back on some 8-bit encoding,
+with non-ASCII code points being read as several CL characters;
+hopefully, if done consistently, that won't affect program behavior too much.")
+
+  (defun always-default-encoding (pathname)
+    "Trivial function to use as *encoding-detection-hook*,
+always 'detects' the *default-encoding*"
+    (declare (ignore pathname))
+    *default-encoding*)
+
+  (defvar *encoding-detection-hook* #'always-default-encoding
+    "Hook for an extension to define a function to automatically detect a file's encoding")
+
+  (defun detect-encoding (pathname)
+    "Detects the encoding of a specified file, going through user-configurable hooks"
+    (if (and pathname (not (directory-pathname-p pathname)) (probe-file* pathname))
+        (funcall *encoding-detection-hook* pathname)
+        *default-encoding*))
+
+  (defun default-encoding-external-format (encoding)
+    "Default, ignorant, function to transform a character ENCODING as a
+portable keyword to an implementation-dependent EXTERNAL-FORMAT specification.
+Load system ASDF-ENCODINGS to hook in a better one."
+    (case encoding
+      (:default :default) ;; for backward-compatibility only. Explicit usage discouraged.
+      (:utf-8 *utf-8-external-format*)
+      (otherwise
+       (cerror "Continue using :external-format :default" (compatfmt "~@<Your ASDF component is using encoding ~S but it isn't recognized. Your system should :defsystem-depends-on (:asdf-encodings).~:>") encoding)
+       :default)))
+
+  (defvar *encoding-external-format-hook*
+    #'default-encoding-external-format
+    "Hook for an extension (e.g. ASDF-ENCODINGS) to define a better mapping
+from non-default encodings to and implementation-defined external-format's")
+
+  (defun encoding-external-format (encoding)
+    "Transform a portable ENCODING keyword to an implementation-dependent EXTERNAL-FORMAT,
+going through all the proper hooks."
+    (funcall *encoding-external-format-hook* (or encoding *default-encoding*))))
+
+
+;;; Safe syntax
+(with-upgradability ()
+  (defvar *standard-readtable* (with-standard-io-syntax *readtable*)
+    "The standard readtable, implementing the syntax specified by the CLHS.
+It must never be modified, though only good implementations will even enforce that.")
+
+  (defmacro with-safe-io-syntax ((&key (package :cl)) &body body)
+    "Establish safe CL reader options around the evaluation of BODY"
+    `(call-with-safe-io-syntax #'(lambda () (let ((*package* (find-package ,package))) ,@body))))
+
+  (defun call-with-safe-io-syntax (thunk &key (package :cl))
+    (with-standard-io-syntax
+      (let ((*package* (find-package package))
+            (*read-default-float-format* 'double-float)
+            (*print-readably* nil)
+            (*read-eval* nil))
+        (funcall thunk))))
+
+  (defun safe-read-from-string (string &key (package :cl) (eof-error-p t) eof-value (start 0) end preserve-whitespace)
+    "Read from STRING using a safe syntax, as per WITH-SAFE-IO-SYNTAX"
+    (with-safe-io-syntax (:package package)
+      (read-from-string string eof-error-p eof-value :start start :end end :preserve-whitespace preserve-whitespace))))
+
+;;; Output helpers
+ (with-upgradability ()
+  (defun call-with-output-file (pathname thunk
+                                &key
+                                  (element-type *default-stream-element-type*)
+                                  (external-format *utf-8-external-format*)
+                                  (if-exists :error)
+                                  (if-does-not-exist :create))
+    "Open FILE for input with given recognizes options, call THUNK with the resulting stream.
+Other keys are accepted but discarded."
+    (with-open-file (s pathname :direction :output
+                                :element-type element-type
+                                :external-format external-format
+                                :if-exists if-exists
+                                :if-does-not-exist if-does-not-exist)
+      (funcall thunk s)))
+
+  (defmacro with-output-file ((var pathname &rest keys
+                               &key element-type external-format if-exists if-does-not-exist)
+                              &body body)
+    (declare (ignore element-type external-format if-exists if-does-not-exist))
+    `(call-with-output-file ,pathname #'(lambda (,var) ,@body) ,@keys))
+
+  (defun call-with-output (output function &key (element-type 'character))
+    "Calls FUNCTION with an actual stream argument,
+behaving like FORMAT with respect to how stream designators are interpreted:
+If OUTPUT is a STREAM, use it as the stream.
+If OUTPUT is NIL, use a STRING-OUTPUT-STREAM of given ELEMENT-TYPE as the stream, and
+return the resulting string.
+If OUTPUT is T, use *STANDARD-OUTPUT* as the stream.
+If OUTPUT is a STRING with a fill-pointer, use it as a STRING-OUTPUT-STREAM of given ELEMENT-TYPE.
+If OUTPUT is a PATHNAME, open the file and write to it, passing ELEMENT-TYPE to WITH-OUTPUT-FILE
+-- this latter as an extension since ASDF 3.1.
+\(Proper ELEMENT-TYPE treatment since ASDF 3.3.4 only.\)
+Otherwise, signal an error."
+    (etypecase output
+      (null
+       (with-output-to-string (stream nil :element-type element-type) (funcall function stream)))
+      ((eql t)
+       (funcall function *standard-output*))
+      (stream
+       (funcall function output))
+      (string
+       (assert (fill-pointer output))
+       (with-output-to-string (stream output :element-type element-type) (funcall function stream)))
+      (pathname
+       (call-with-output-file output function :element-type element-type)))))
+
+(with-upgradability ()
+  (locally (declare #+sbcl (sb-ext:muffle-conditions style-warning))
+    (handler-bind (#+sbcl (style-warning #'muffle-warning))
+      (defmacro with-output ((output-var &optional (value output-var) &key element-type) &body body)
+        "Bind OUTPUT-VAR to an output stream obtained from VALUE (default: previous binding
+of OUTPUT-VAR) treated as a stream designator per CALL-WITH-OUTPUT. Evaluate BODY in
+the scope of this binding."
+        `(call-with-output ,value #'(lambda (,output-var) ,@body)
+                           ,@(when element-type `(:element-type ,element-type)))))))
+
+(defun output-string (string &optional output)
+  "If the desired OUTPUT is not NIL, print the string to the output; otherwise return the string"
+  (if output
+      (with-output (output) (princ string output))
+      string))
+
+
+;;; Input helpers
+(with-upgradability ()
+  (defun call-with-input-file (pathname thunk
+                               &key
+                                 (element-type *default-stream-element-type*)
+                                 (external-format *utf-8-external-format*)
+                                 (if-does-not-exist :error))
+    "Open FILE for input with given recognizes options, call THUNK with the resulting stream.
+Other keys are accepted but discarded."
+    (with-open-file (s pathname :direction :input
+                                :element-type element-type
+                                :external-format external-format
+                                :if-does-not-exist if-does-not-exist)
+      (funcall thunk s)))
+
+  (defmacro with-input-file ((var pathname &rest keys
+                              &key element-type external-format if-does-not-exist)
+                             &body body)
+    (declare (ignore element-type external-format if-does-not-exist))
+    `(call-with-input-file ,pathname #'(lambda (,var) ,@body) ,@keys))
+
+  (defun call-with-input (input function &key keys)
+    "Calls FUNCTION with an actual stream argument, interpreting
+stream designators like READ, but also coercing strings to STRING-INPUT-STREAM,
+and PATHNAME to FILE-STREAM.
+If INPUT is a STREAM, use it as the stream.
+If INPUT is NIL, use a *STANDARD-INPUT* as the stream.
+If INPUT is T, use *TERMINAL-IO* as the stream.
+If INPUT is a STRING, use it as a string-input-stream.
+If INPUT is a PATHNAME, open it, passing KEYS to WITH-INPUT-FILE
+-- the latter is an extension since ASDF 3.1.
+Otherwise, signal an error."
+    (etypecase input
+      (null (funcall function *standard-input*))
+      ((eql t) (funcall function *terminal-io*))
+      (stream (funcall function input))
+      (string (with-input-from-string (stream input) (funcall function stream)))
+      (pathname (apply 'call-with-input-file input function keys))))
+
+  (defmacro with-input ((input-var &optional (value input-var)) &body body)
+    "Bind INPUT-VAR to an input stream, coercing VALUE (default: previous binding of INPUT-VAR)
+as per CALL-WITH-INPUT, and evaluate BODY within the scope of this binding."
+    `(call-with-input ,value #'(lambda (,input-var) ,@body)))
+
+  (defun input-string (&optional input)
+    "If the desired INPUT is a string, return that string; otherwise slurp the INPUT into a string
+and return that"
+    (if (stringp input)
+        input
+        (with-input (input) (funcall 'slurp-stream-string input)))))
+
+;;; Null device
+(with-upgradability ()
+  (defun null-device-pathname ()
+    "Pathname to a bit bucket device that discards any information written to it
+and always returns EOF when read from"
+    (os-cond
+      ((os-unix-p) #p"/dev/null")
+      ((os-windows-p) #p"NUL") ;; Q: how many Lisps accept the #p"NUL:" syntax?
+      (t (error "No /dev/null on your OS"))))
+  (defun call-with-null-input (fun &key element-type external-format if-does-not-exist)
+    "Call FUN with an input stream that always returns end of file.
+The keyword arguments are allowed for backward compatibility, but are ignored."
+    (declare (ignore element-type external-format if-does-not-exist))
+    (with-open-stream (input (make-concatenated-stream))
+      (funcall fun input)))
+  (defmacro with-null-input ((var &rest keys
+                              &key element-type external-format if-does-not-exist)
+                             &body body)
+    (declare (ignore element-type external-format if-does-not-exist))
+    "Evaluate BODY in a context when VAR is bound to an input stream that always returns end of file.
+The keyword arguments are allowed for backward compatibility, but are ignored."
+    `(call-with-null-input #'(lambda (,var) ,@body) ,@keys))
+  (defun call-with-null-output (fun
+                                &key (element-type *default-stream-element-type*)
+                                  (external-format *utf-8-external-format*)
+                                  (if-exists :overwrite)
+                                  (if-does-not-exist :error))
+    (declare (ignore element-type external-format if-exists if-does-not-exist))
+    "Call FUN with an output stream that discards all output.
+The keyword arguments are allowed for backward compatibility, but are ignored."
+    (with-open-stream (output (make-broadcast-stream))
+      (funcall fun output)))
+  (defmacro with-null-output ((var &rest keys
+                              &key element-type external-format if-does-not-exist if-exists)
+                              &body body)
+    "Evaluate BODY in a context when VAR is bound to an output stream that discards all output.
+The keyword arguments are allowed for backward compatibility, but are ignored."
+    (declare (ignore element-type external-format if-exists if-does-not-exist))
+    `(call-with-null-output #'(lambda (,var) ,@body) ,@keys)))
+
+;;; Ensure output buffers are flushed
+(with-upgradability ()
+  (defun finish-outputs (&rest streams)
+    "Finish output on the main output streams as well as any specified one.
+Useful for portably flushing I/O before user input or program exit."
+    ;; CCL notably buffers its stream output by default.
+    (dolist (s (append streams
+                       (list *stdout* *stderr* *error-output* *standard-output* *trace-output*
+                             *debug-io* *terminal-io* *query-io*)))
+      (ignore-errors (finish-output s)))
+    (values))
+
+  (defun format! (stream format &rest args)
+    "Just like format, but call finish-outputs before and after the output."
+    (finish-outputs stream)
+    (apply 'format stream format args)
+    (finish-outputs stream))
+
+  (defun safe-format! (stream format &rest args)
+    "Variant of FORMAT that is safe against both
+dangerous syntax configuration and errors while printing."
+    (with-safe-io-syntax ()
+      (ignore-errors (apply 'format! stream format args))
+      (finish-outputs stream)))) ; just in case format failed
+
+
+;;; Simple Whole-Stream processing
+(with-upgradability ()
+  (defun copy-stream-to-stream (input output &key element-type buffer-size linewise prefix)
+    "Copy the contents of the INPUT stream into the OUTPUT stream.
+If LINEWISE is true, then read and copy the stream line by line, with an optional PREFIX.
+Otherwise, using WRITE-SEQUENCE using a buffer of size BUFFER-SIZE."
+    (with-open-stream (input input)
+      (if linewise
+          (loop :for (line eof) = (multiple-value-list (read-line input nil nil))
+                :while line :do
+                  (when prefix (princ prefix output))
+                  (princ line output)
+                  (unless eof (terpri output))
+                  (finish-output output)
+                  (when eof (return)))
+          (loop
+            :with buffer-size = (or buffer-size 8192)
+            :with buffer = (make-array (list buffer-size) :element-type (or element-type 'character))
+            :for end = (read-sequence buffer input)
+            :until (zerop end)
+            :do (write-sequence buffer output :end end)
+                (when (< end buffer-size) (return))))))
+
+  (defun concatenate-files (inputs output)
+    "create a new OUTPUT file the contents of which a the concatenate of the INPUTS files."
+    (with-open-file (o output :element-type '(unsigned-byte 8)
+                              :direction :output :if-exists :rename-and-delete)
+      (dolist (input inputs)
+        (with-open-file (i input :element-type '(unsigned-byte 8)
+                                 :direction :input :if-does-not-exist :error)
+          (copy-stream-to-stream i o :element-type '(unsigned-byte 8))))))
+
+  (defun copy-file (input output)
+    "Copy contents of the INPUT file to the OUTPUT file"
+    ;; Not available on LW personal edition or LW 6.0 on Mac: (lispworks:copy-file i f)
+    #+allegro
+    (excl.osi:copy-file input output)
+    #+ecl
+    (ext:copy-file input output)
+    #-(or allegro ecl)
+    (concatenate-files (list input) output))
+
+  (defun slurp-stream-string (input &key (element-type 'character) stripped)
+    "Read the contents of the INPUT stream as a string"
+    (let ((string
+            (with-open-stream (input input)
+              (with-output-to-string (output nil :element-type element-type)
+                (copy-stream-to-stream input output :element-type element-type)))))
+      (if stripped (stripln string) string)))
+
+  (defun slurp-stream-lines (input &key count)
+    "Read the contents of the INPUT stream as a list of lines, return those lines.
+
+Note: relies on the Lisp's READ-LINE, but additionally removes any remaining CR
+from the line-ending if the file or stream had CR+LF but Lisp only removed LF.
+
+Read no more than COUNT lines."
+    (check-type count (or null integer))
+    (with-open-stream (input input)
+      (loop :for n :from 0
+            :for l = (and (or (not count) (< n count))
+                          (read-line input nil nil))
+            ;; stripln: to remove CR when the OS sends CRLF and Lisp only remove LF
+            :while l :collect (stripln l))))
+
+  (defun slurp-stream-line (input &key (at 0))
+    "Read the contents of the INPUT stream as a list of lines,
+then return the ACCESS-AT of that list of lines using the AT specifier.
+PATH defaults to 0, i.e. return the first line.
+PATH is typically an integer, or a list of an integer and a function.
+If PATH is NIL, it will return all the lines in the file.
+
+The stream will not be read beyond the Nth lines,
+where N is the index specified by path
+if path is either an integer or a list that starts with an integer."
+    (access-at (slurp-stream-lines input :count (access-at-count at)) at))
+
+  (defun slurp-stream-forms (input &key count)
+    "Read the contents of the INPUT stream as a list of forms,
+and return those forms.
+
+If COUNT is null, read to the end of the stream;
+if COUNT is an integer, stop after COUNT forms were read.
+
+BEWARE: be sure to use WITH-SAFE-IO-SYNTAX, or some variant thereof"
+    (check-type count (or null integer))
+    (loop :with eof = '#:eof
+          :for n :from 0
+          :for form = (if (and count (>= n count))
+                          eof
+                          (read-preserving-whitespace input nil eof))
+          :until (eq form eof) :collect form))
+
+  (defun slurp-stream-form (input &key (at 0))
+    "Read the contents of the INPUT stream as a list of forms,
+then return the ACCESS-AT of these forms following the AT.
+AT defaults to 0, i.e. return the first form.
+AT is typically a list of integers.
+If AT is NIL, it will return all the forms in the file.
+
+The stream will not be read beyond the Nth form,
+where N is the index specified by path,
+if path is either an integer or a list that starts with an integer.
+
+BEWARE: be sure to use WITH-SAFE-IO-SYNTAX, or some variant thereof"
+    (access-at (slurp-stream-forms input :count (access-at-count at)) at))
+
+  (defun read-file-string (file &rest keys)
+    "Open FILE with option KEYS, read its contents as a string"
+    (apply 'call-with-input-file file 'slurp-stream-string keys))
+
+  (defun read-file-lines (file &rest keys)
+    "Open FILE with option KEYS, read its contents as a list of lines
+BEWARE: be sure to use WITH-SAFE-IO-SYNTAX, or some variant thereof"
+    (apply 'call-with-input-file file 'slurp-stream-lines keys))
+
+  (defun read-file-line (file &rest keys &key (at 0) &allow-other-keys)
+    "Open input FILE with option KEYS (except AT),
+and read its contents as per SLURP-STREAM-LINE with given AT specifier.
+BEWARE: be sure to use WITH-SAFE-IO-SYNTAX, or some variant thereof"
+    (apply 'call-with-input-file file
+           #'(lambda (input) (slurp-stream-line input :at at))
+           (remove-plist-key :at keys)))
+
+  (defun read-file-forms (file &rest keys &key count &allow-other-keys)
+    "Open input FILE with option KEYS (except COUNT),
+and read its contents as per SLURP-STREAM-FORMS with given COUNT.
+If COUNT is null, read to the end of the stream;
+if COUNT is an integer, stop after COUNT forms were read.
+BEWARE: be sure to use WITH-SAFE-IO-SYNTAX, or some variant thereof"
+    (apply 'call-with-input-file file
+           #'(lambda (input) (slurp-stream-forms input :count count))
+           (remove-plist-key :count keys)))
+
+  (defun read-file-form (file &rest keys &key (at 0) &allow-other-keys)
+    "Open input FILE with option KEYS (except AT),
+and read its contents as per SLURP-STREAM-FORM with given AT specifier.
+BEWARE: be sure to use WITH-SAFE-IO-SYNTAX, or some variant thereof"
+    (apply 'call-with-input-file file
+           #'(lambda (input) (slurp-stream-form input :at at))
+           (remove-plist-key :at keys)))
+
+  (defun safe-read-file-line (pathname &rest keys &key (package :cl) &allow-other-keys)
+    "Reads the specified line from the top of a file using a safe standardized syntax.
+Extracts the line using READ-FILE-LINE,
+within an WITH-SAFE-IO-SYNTAX using the specified PACKAGE."
+    (with-safe-io-syntax (:package package)
+      (apply 'read-file-line pathname (remove-plist-key :package keys))))
+
+  (defun safe-read-file-form (pathname &rest keys &key (package :cl) &allow-other-keys)
+    "Reads the specified form from the top of a file using a safe standardized syntax.
+Extracts the form using READ-FILE-FORM,
+within an WITH-SAFE-IO-SYNTAX using the specified PACKAGE."
+    (with-safe-io-syntax (:package package)
+      (apply 'read-file-form pathname (remove-plist-key :package keys))))
+
+  (defun eval-input (input)
+    "Portably read and evaluate forms from INPUT, return the last values."
+    (with-input (input)
+      (loop :with results :with eof ='#:eof
+            :for form = (read input nil eof)
+            :until (eq form eof)
+            :do (setf results (multiple-value-list (eval form)))
+            :finally (return (values-list results)))))
+
+  (defun eval-thunk (thunk)
+    "Evaluate a THUNK of code:
+If a function, FUNCALL it without arguments.
+If a constant literal and not a sequence, return it.
+If a cons or a symbol, EVAL it.
+If a string, repeatedly read and evaluate from it, returning the last values."
+    (etypecase thunk
+      ((or boolean keyword number character pathname) thunk)
+      ((or cons symbol) (eval thunk))
+      (function (funcall thunk))
+      (string (eval-input thunk))))
+
+  (defun standard-eval-thunk (thunk &key (package :cl))
+    "Like EVAL-THUNK, but in a more standardized evaluation context."
+    ;; Note: it's "standard-" not "safe-", because evaluation is never safe.
+    (when thunk
+      (with-safe-io-syntax (:package package)
+        (let ((*read-eval* t))
+          (eval-thunk thunk))))))
+
+(with-upgradability ()
+  (defun println (x &optional (stream *standard-output*))
+    "Variant of PRINC that also calls TERPRI afterwards"
+    (princ x stream) (terpri stream) (finish-output stream) (values))
+
+  (defun writeln (x &rest keys &key (stream *standard-output*) &allow-other-keys)
+    "Variant of WRITE that also calls TERPRI afterwards"
+    (apply 'write x keys) (terpri stream) (finish-output stream) (values)))
+
+
+;;; Using temporary files
+(with-upgradability ()
+  (defun default-temporary-directory ()
+    "Return a default directory to use for temporary files"
+    (os-cond
+      ((os-unix-p)
+       (or (getenv-pathname "TMPDIR" :ensure-directory t)
+           (parse-native-namestring "/tmp/")))
+      ((os-windows-p)
+       (getenv-pathname "TEMP" :ensure-directory t))
+      (t (subpathname (user-homedir-pathname) "tmp/"))))
+
+  (defvar *temporary-directory* nil "User-configurable location for temporary files")
+
+  (defun temporary-directory ()
+    "Return a directory to use for temporary files"
+    (or *temporary-directory* (default-temporary-directory)))
+
+  (defun setup-temporary-directory ()
+    "Configure a default temporary directory to use."
+    (setf *temporary-directory* (default-temporary-directory))
+    #+gcl (setf system::*tmp-dir* *temporary-directory*))
+
+  (defun call-with-temporary-file
+      (thunk &key
+               (want-stream-p t) (want-pathname-p t) (direction :io) keep after
+               directory (type "tmp" typep) prefix (suffix (when typep "-tmp"))
+               (element-type *default-stream-element-type*)
+               (external-format *utf-8-external-format*))
+    "Call a THUNK with stream and/or pathname arguments identifying a temporary file.
+
+The temporary file's pathname will be based on concatenating
+PREFIX (or \"tmp\" if it's NIL), a random alphanumeric string,
+and optional SUFFIX (defaults to \"-tmp\" if a type was provided)
+and TYPE (defaults to \"tmp\", using a dot as separator if not NIL),
+within DIRECTORY (defaulting to the TEMPORARY-DIRECTORY) if the PREFIX isn't absolute.
+
+The file will be open with specified DIRECTION (defaults to :IO),
+ELEMENT-TYPE (defaults to *DEFAULT-STREAM-ELEMENT-TYPE*) and
+EXTERNAL-FORMAT (defaults to *UTF-8-EXTERNAL-FORMAT*).
+If WANT-STREAM-P is true (the defaults to T), then THUNK will then be CALL-FUNCTION'ed
+with the stream and the pathname (if WANT-PATHNAME-P is true, defaults to T),
+and stream will be closed after the THUNK exits (either normally or abnormally).
+If WANT-STREAM-P is false, then WANT-PATHAME-P must be true, and then
+THUNK is only CALL-FUNCTION'ed after the stream is closed, with the pathname as argument.
+Upon exit of THUNK, the AFTER thunk if defined is CALL-FUNCTION'ed with the pathname as argument.
+If AFTER is defined, its results are returned, otherwise, the results of THUNK are returned.
+Finally, the file will be deleted, unless the KEEP argument when CALL-FUNCTION'ed returns true."
+    #+xcl (declare (ignorable typep))
+    (check-type direction (member :output :io))
+    (assert (or want-stream-p want-pathname-p))
+    (loop
+      :with prefix-pn = (ensure-absolute-pathname
+                         (or prefix "tmp")
+                         (or (ensure-pathname
+                              directory
+                              :namestring :native
+                              :ensure-directory t
+                              :ensure-physical t)
+                             #'temporary-directory))
+      :with prefix-nns = (native-namestring prefix-pn)
+      :with results = (progn (ensure-directories-exist prefix-pn)
+                             ())
+      :for counter :from (random (expt 36 #-gcl 8 #+gcl 5))
+      :for pathname = (parse-native-namestring
+                       (format nil "~A~36R~@[~A~]~@[.~A~]"
+                               prefix-nns counter suffix (unless (eq type :unspecific) type)))
+      :for okp = nil :do
+        ;; TODO: on Unix, do something about umask
+        ;; TODO: on Unix, audit the code so we make sure it uses O_CREAT|O_EXCL
+        ;; TODO: on Unix, use CFFI and mkstemp --
+        ;; except UIOP is precisely meant to not depend on CFFI or on anything! Grrrr.
+        ;; Can we at least design some hook?
+        (unwind-protect
+             (progn
+               (ensure-directories-exist pathname)
+               (with-open-file (stream pathname
+                                       :direction direction
+                                       :element-type element-type
+                                       :external-format external-format
+                                       :if-exists nil :if-does-not-exist :create)
+                 (when stream
+                   (setf okp pathname)
+                   (when want-stream-p
+                     ;; Note: can't return directly from within with-open-file
+                     ;; or the non-local return causes the file creation to be undone.
+                     (setf results (multiple-value-list
+                                    (if want-pathname-p
+                                        (call-function thunk stream pathname)
+                                        (call-function thunk stream)))))))
+               ;; if we don't want a stream, then we must call the thunk *after*
+               ;; the stream is closed, but only if it was successfully opened.
+               (when okp
+                 (when (and want-pathname-p (not want-stream-p))
+                   (setf results (multiple-value-list (call-function thunk okp))))
+                 ;; if the stream was successfully opened, then return a value,
+                 ;; either one computed already, or one from AFTER, if that exists.
+                 (if after
+                     (return (call-function after pathname))
+                     (return (values-list results)))))
+          (when (and okp (not (call-function keep)))
+            (ignore-errors (delete-file-if-exists okp))))))
+
+  (defmacro with-temporary-file ((&key (stream (gensym "STREAM") streamp)
+                                    (pathname (gensym "PATHNAME") pathnamep)
+                                    directory prefix suffix type
+                                    keep direction element-type external-format)
+                                 &body body)
+    "Evaluate BODY where the symbols specified by keyword arguments
+STREAM and PATHNAME (if respectively specified) are bound corresponding
+to a newly created temporary file ready for I/O, as per CALL-WITH-TEMPORARY-FILE.
+At least one of STREAM or PATHNAME must be specified.
+If the STREAM is not specified, it will be closed before the BODY is evaluated.
+If STREAM is specified, then the :CLOSE-STREAM label if it appears in the BODY,
+separates forms run before and after the stream is closed.
+The values of the last form of the BODY (not counting the separating :CLOSE-STREAM) are returned.
+Upon success, the KEEP form is evaluated and the file is is deleted unless it evaluates to TRUE."
+    (check-type stream symbol)
+    (check-type pathname symbol)
+    (assert (or streamp pathnamep))
+    (let* ((afterp (position :close-stream body))
+           (before (if afterp (subseq body 0 afterp) body))
+           (after (when afterp (subseq body (1+ afterp))))
+           (beforef (gensym "BEFORE"))
+           (afterf (gensym "AFTER")))
+      (when (eql afterp 0)
+        (style-warn ":CLOSE-STREAM should not be the first form of BODY in WITH-TEMPORARY-FILE. Instead, do not provide a STREAM."))
+      `(flet (,@(when before
+                  `((,beforef (,@(when streamp `(,stream)) ,@(when pathnamep `(,pathname)))
+                       ,@(when after `((declare (ignorable ,pathname))))
+                       ,@before)))
+              ,@(when after
+                  (assert pathnamep)
+                  `((,afterf (,pathname) ,@after))))
+         #-gcl (declare (dynamic-extent ,@(when before `(#',beforef)) ,@(when after `(#',afterf))))
+         (call-with-temporary-file
+          ,(when before `#',beforef)
+          :want-stream-p ,streamp
+          :want-pathname-p ,pathnamep
+          ,@(when direction `(:direction ,direction))
+          ,@(when directory `(:directory ,directory))
+          ,@(when prefix `(:prefix ,prefix))
+          ,@(when suffix `(:suffix ,suffix))
+          ,@(when type `(:type ,type))
+          ,@(when keep `(:keep ,keep))
+          ,@(when after `(:after #',afterf))
+          ,@(when element-type `(:element-type ,element-type))
+          ,@(when external-format `(:external-format ,external-format))))))
+
+  (defun get-temporary-file (&key directory prefix suffix type (keep t))
+    (with-temporary-file (:pathname pn :keep keep
+                          :directory directory :prefix prefix :suffix suffix :type type)
+      pn))
+
+  ;; Temporary pathnames in simple cases where no contention is assumed
+  (defun add-pathname-suffix (pathname suffix &rest keys)
+    "Add a SUFFIX to the name of a PATHNAME, return a new pathname.
+Further KEYS can be passed to MAKE-PATHNAME."
+    (apply 'make-pathname :name (strcat (pathname-name pathname) suffix)
+                          :defaults pathname keys))
+
+  (defun tmpize-pathname (x)
+    "Return a new pathname modified from X by adding a trivial random suffix.
+A new empty file with said temporary pathname is created, to ensure there is no
+clash with any concurrent process attempting the same thing."
+    (let* ((px (ensure-pathname x :ensure-physical t))
+           (prefix (if-let (n (pathname-name px)) (strcat n "-tmp") "tmp"))
+           (directory (pathname-directory-pathname px)))
+      ;; Genera uses versioned pathnames -- If we leave the empty file in place,
+      ;; the system will create a new version of the file when the caller opens
+      ;; it for output. That empty file will remain after the operation is completed.
+      ;; As Genera is a single core processor, the possibility of a name conflict is
+      ;; minimal if not nil. (And, in the event of a collision, the two processes
+      ;; would be writing to different versions of the file.)
+      (get-temporary-file :directory directory :prefix prefix :type (pathname-type px)
+                          #+genera :keep #+genera nil)))
+
+  (defun call-with-staging-pathname (pathname fun)
+    "Calls FUN with a staging pathname, and atomically
+renames the staging pathname to the PATHNAME in the end.
+NB: this protects only against failure of the program, not against concurrent attempts.
+For the latter case, we ought pick a random suffix and atomically open it."
+    (let* ((pathname (pathname pathname))
+           (staging (tmpize-pathname pathname)))
+      (unwind-protect
+           (multiple-value-prog1
+               (funcall fun staging)
+             (rename-file-overwriting-target staging pathname))
+        (delete-file-if-exists staging))))
+
+  (defmacro with-staging-pathname ((pathname-var &optional (pathname-value pathname-var)) &body body)
+    "Trivial syntax wrapper for CALL-WITH-STAGING-PATHNAME"
+    `(call-with-staging-pathname ,pathname-value #'(lambda (,pathname-var) ,@body))))
+
+(with-upgradability ()
+  (defun file-stream-p (stream)
+    (typep stream 'file-stream))
+  (defun file-or-synonym-stream-p (stream)
+    (or (file-stream-p stream)
+        (and (typep stream 'synonym-stream)
+             (file-or-synonym-stream-p
+              (symbol-value (synonym-stream-symbol stream)))))))
+;;;; -------------------------------------------------------------------------
+;;;; Starting, Stopping, Dumping a Lisp image
+
+(uiop/package:define-package :uiop/image
+  (:use :uiop/common-lisp :uiop/package :uiop/utility :uiop/pathname :uiop/stream :uiop/os)
+  (:export
+   #:*image-dumped-p* #:raw-command-line-arguments #:*command-line-arguments*
+   #:command-line-arguments #:raw-command-line-arguments #:setup-command-line-arguments #:argv0
+   #:*lisp-interaction*
+   #:fatal-condition #:fatal-condition-p
+   #:handle-fatal-condition
+   #:call-with-fatal-condition-handler #:with-fatal-condition-handler
+   #:*image-restore-hook* #:*image-prelude* #:*image-entry-point*
+   #:*image-postlude* #:*image-dump-hook*
+   #:quit #:die #:raw-print-backtrace #:print-backtrace #:print-condition-backtrace
+   #:shell-boolean-exit
+   #:register-image-restore-hook #:register-image-dump-hook
+   #:call-image-restore-hook #:call-image-dump-hook
+   #:restore-image #:dump-image #:create-image
+))
+(in-package :uiop/image)
+
+(with-upgradability ()
+  (defvar *lisp-interaction* t
+    "Is this an interactive Lisp environment, or is it batch processing?")
+
+  (defvar *command-line-arguments* nil
+    "Command-line arguments")
+
+  (defvar *image-dumped-p* nil ; may matter as to how to get to command-line-arguments
+    "Is this a dumped image? As a standalone executable?")
+
+  (defvar *image-restore-hook* nil
+    "Functions to call (in reverse order) when the image is restored")
+
+  (defvar *image-restored-p* nil
+    "Has the image been restored? A boolean, or :in-progress while restoring, :in-regress while dumping")
+
+  (defvar *image-prelude* nil
+    "a form to evaluate, or string containing forms to read and evaluate
+when the image is restarted, but before the entry point is called.")
+
+  (defvar *image-entry-point* nil
+    "a function with which to restart the dumped image when execution is restored from it.")
+
+  (defvar *image-postlude* nil
+    "a form to evaluate, or string containing forms to read and evaluate
+before the image dump hooks are called and before the image is dumped.")
+
+  (defvar *image-dump-hook* nil
+    "Functions to call (in order) when before an image is dumped"))
+
+(eval-when (#-lispworks :compile-toplevel :load-toplevel :execute)
+  (deftype fatal-condition ()
+    `(and serious-condition #+clozure (not ccl:process-reset))))
+
+;;; Exiting properly or im-
+(with-upgradability ()
+  (defun quit (&optional (code 0) (finish-output t))
+    "Quits from the Lisp world, with the given exit status if provided.
+This is designed to abstract away the implementation specific quit forms."
+    (when finish-output ;; essential, for ClozureCL, and for standard compliance.
+      (finish-outputs))
+    #+(or abcl xcl) (ext:quit :status code)
+    #+allegro (excl:exit code :quiet t)
+    #+(or clasp ecl) (si:quit code)
+    #+clisp (ext:quit code)
+    #+clozure (ccl:quit code)
+    #+cormanlisp (win32:exitprocess code)
+    #+(or cmucl scl) (unix:unix-exit code)
+    #+gcl (system:quit code)
+    #+genera (error "~S: You probably don't want to Halt Genera. (code: ~S)" 'quit code)
+    #+lispworks (lispworks:quit :status code :confirm nil :return nil :ignore-errors-p t)
+    #+mcl (progn code (ccl:quit)) ;; or should we use FFI to call libc's exit(3) ?
+    #+mkcl (mk-ext:quit :exit-code code)
+    #+sbcl #.(let ((exit (find-symbol* :exit :sb-ext nil))
+                   (quit (find-symbol* :quit :sb-ext nil)))
+               (cond
+                 (exit `(,exit :code code :abort (not finish-output)))
+                 (quit `(,quit :unix-status code :recklessly-p (not finish-output)))))
+    #-(or abcl allegro clasp clisp clozure cmucl ecl gcl genera lispworks mcl mkcl sbcl scl xcl)
+    (not-implemented-error 'quit "(called with exit code ~S)" code))
+
+  (defun die (code format &rest arguments)
+    "Die in error with some error message"
+    (with-safe-io-syntax ()
+      (ignore-errors
+       (format! *stderr* "~&~?~&" format arguments)))
+    (quit code))
+
+  (defun raw-print-backtrace (&key (stream *debug-io*) count condition)
+    "Print a backtrace, directly accessing the implementation"
+    (declare (ignorable stream count condition))
+    #+abcl
+    (loop :for i :from 0
+          :for frame :in (sys:backtrace (or count most-positive-fixnum)) :do
+            (safe-format! stream "~&~D: ~A~%" i frame))
+    #+allegro
+    (let ((*terminal-io* stream)
+          (*standard-output* stream)
+          (tpl:*zoom-print-circle* *print-circle*)
+          (tpl:*zoom-print-level* *print-level*)
+          (tpl:*zoom-print-length* *print-length*))
+      (tpl:do-command "zoom"
+        :from-read-eval-print-loop nil
+        :count (or count t)
+        :all t))
+    #+clasp
+    (clasp-debug:print-backtrace :stream stream :count count)
+    #+(or ecl mkcl)
+    (let* ((top (si:ihs-top))
+           (repeats (if count (min top count) top))
+           (backtrace (loop :for ihs :from 0 :below top
+                            :collect (list (si::ihs-fun ihs)
+                                           (si::ihs-env ihs)))))
+      (loop :for i :from 0 :below repeats
+            :for frame :in (nreverse backtrace) :do
+              (safe-format! stream "~&~D: ~S~%" i frame)))
+    #+clisp
+    (system::print-backtrace :out stream :limit count)
+    #+(or clozure mcl)
+    (let ((*debug-io* stream))
+      #+clozure (ccl:print-call-history :count count :start-frame-number 1)
+      #+mcl (ccl:print-call-history :detailed-p nil)
+      (finish-output stream))
+    #+(or cmucl scl)
+    (let ((debug:*debug-print-level* *print-level*)
+          (debug:*debug-print-length* *print-length*))
+      (debug:backtrace (or count most-positive-fixnum) stream))
+    #+gcl
+    (let ((*debug-io* stream))
+      (ignore-errors
+       (with-safe-io-syntax ()
+         (if condition
+             (conditions::condition-backtrace condition)
+             (system::simple-backtrace)))))
+    #+lispworks
+    (let ((dbg::*debugger-stack*
+            (dbg::grab-stack nil :how-many (or count most-positive-fixnum)))
+          (*debug-io* stream)
+          (dbg:*debug-print-level* *print-level*)
+          (dbg:*debug-print-length* *print-length*))
+      (dbg:bug-backtrace nil))
+    #+mezzano
+    (let ((*standard-output* stream))
+      (sys.int::backtrace count))
+    #+sbcl
+    (sb-debug:print-backtrace :stream stream :count (or count most-positive-fixnum))
+    #+xcl
+    (loop :for i :from 0 :below (or count most-positive-fixnum)
+          :for frame :in (extensions:backtrace-as-list) :do
+            (safe-format! stream "~&~D: ~S~%" i frame)))
+
+  (defun print-backtrace (&rest keys &key stream count condition)
+    "Print a backtrace"
+    (declare (ignore stream count condition))
+    (with-safe-io-syntax (:package :cl)
+      (let ((*print-readably* nil)
+            (*print-circle* t)
+            (*print-miser-width* 75)
+            (*print-length* nil)
+            (*print-level* nil)
+            (*print-pretty* t))
+        (ignore-errors (apply 'raw-print-backtrace keys)))))
+
+  (defun print-condition-backtrace (condition &key (stream *stderr*) count)
+    "Print a condition after a backtrace triggered by that condition"
+    ;; We print the condition *after* the backtrace,
+    ;; for the sake of who sees the backtrace at a terminal.
+    ;; It is up to the caller to print the condition *before*, with some context.
+    (print-backtrace :stream stream :count count :condition condition)
+    (when condition
+      (safe-format! stream "~&Above backtrace due to this condition:~%~A~&"
+                    condition)))
+
+  (defun fatal-condition-p (condition)
+    "Is the CONDITION fatal?"
+    (typep condition 'fatal-condition))
+
+  (defun handle-fatal-condition (condition)
+    "Handle a fatal CONDITION:
+depending on whether *LISP-INTERACTION* is set, enter debugger or die"
+    (cond
+      (*lisp-interaction*
+       (invoke-debugger condition))
+      (t
+       (safe-format! *stderr* "~&Fatal condition:~%~A~%" condition)
+       (print-condition-backtrace condition :stream *stderr*)
+       (die 99 "~A" condition))))
+
+  (defun call-with-fatal-condition-handler (thunk)
+    "Call THUNK in a context where fatal conditions are appropriately handled"
+    (handler-bind ((fatal-condition #'handle-fatal-condition))
+      (funcall thunk)))
+
+  (defmacro with-fatal-condition-handler ((&optional) &body body)
+    "Execute BODY in a context where fatal conditions are appropriately handled"
+    `(call-with-fatal-condition-handler #'(lambda () ,@body)))
+
+  (defun shell-boolean-exit (x)
+    "Quit with a return code that is 0 iff argument X is true"
+    (quit (if x 0 1))))
+
+
+;;; Using image hooks
+(with-upgradability ()
+  (defun register-image-restore-hook (hook &optional (call-now-p t))
+    "Regiter a hook function to be run when restoring a dumped image"
+    (register-hook-function '*image-restore-hook* hook call-now-p))
+
+  (defun register-image-dump-hook (hook &optional (call-now-p nil))
+    "Register a the hook function to be run before to dump an image"
+    (register-hook-function '*image-dump-hook* hook call-now-p))
+
+  (defun call-image-restore-hook ()
+    "Call the hook functions registered to be run when restoring a dumped image"
+    (call-functions (reverse *image-restore-hook*)))
+
+  (defun call-image-dump-hook ()
+    "Call the hook functions registered to be run before to dump an image"
+    (call-functions *image-dump-hook*)))
+
+
+;;; Proper command-line arguments
+(with-upgradability ()
+  (defun raw-command-line-arguments ()
+    "Find what the actual command line for this process was."
+    #+abcl ext:*command-line-argument-list* ; Use 1.0.0 or later!
+    #+allegro (sys:command-line-arguments) ; default: :application t
+    #+(or clasp ecl) (loop :for i :from 0 :below (si:argc) :collect (si:argv i))
+    #+clisp (coerce (ext:argv) 'list)
+    #+clozure ccl:*command-line-argument-list*
+    #+(or cmucl scl) extensions:*command-line-strings*
+    #+gcl si:*command-args*
+    #+(or genera mcl mezzano) nil
+    #+lispworks sys:*line-arguments-list*
+    #+mkcl (loop :for i :from 0 :below (mkcl:argc) :collect (mkcl:argv i))
+    #+sbcl sb-ext:*posix-argv*
+    #+xcl system:*argv*
+    #-(or abcl allegro clasp clisp clozure cmucl ecl gcl genera lispworks mcl mezzano mkcl sbcl scl xcl)
+    (not-implemented-error 'raw-command-line-arguments))
+
+  (defun command-line-arguments (&optional (arguments (raw-command-line-arguments)))
+    "Extract user arguments from command-line invocation of current process.
+Assume the calling conventions of a generated script that uses --
+if we are not called from a directly executable image."
+    (block nil
+      #+abcl (return arguments)
+      ;; SBCL and Allegro already separate user arguments from implementation arguments.
+      #-(or sbcl allegro)
+      (unless (eq *image-dumped-p* :executable)
+        ;; LispWorks command-line processing isn't transparent to the user
+        ;; unless you create a standalone executable; in that case,
+        ;; we rely on cl-launch or some other script to set the arguments for us.
+        #+lispworks (return *command-line-arguments*)
+        ;; On other implementations, on non-standalone executables,
+        ;; we trust cl-launch or whichever script starts the program
+        ;; to use -- as a delimiter between implementation arguments and user arguments.
+        #-lispworks (setf arguments (member "--" arguments :test 'string-equal)))
+      (rest arguments)))
+
+  (defun argv0 ()
+    "On supported implementations (most that matter), or when invoked by a proper wrapper script,
+return a string that for the name with which the program was invoked, i.e. argv[0] in C.
+Otherwise, return NIL."
+    (cond
+      ((eq *image-dumped-p* :executable) ; yes, this ARGV0 is our argv0 !
+       ;; NB: not currently available on ABCL, Corman, Genera, MCL
+       (or #+(or allegro clisp clozure cmucl gcl lispworks sbcl scl xcl)
+           (first (raw-command-line-arguments))
+           #+(or clasp ecl) (si:argv 0) #+mkcl (mkcl:argv 0)))
+      (t ;; argv[0] is the name of the interpreter.
+       ;; The wrapper script can export __CL_ARGV0. cl-launch does as of 4.0.1.8.
+       (getenvp "__CL_ARGV0"))))
+
+  (defun setup-command-line-arguments ()
+    (setf *command-line-arguments* (command-line-arguments)))
+
+  (defun restore-image (&key
+                          (lisp-interaction *lisp-interaction*)
+                          (restore-hook *image-restore-hook*)
+                          (prelude *image-prelude*)
+                          (entry-point *image-entry-point*)
+                          (if-already-restored '(cerror "RUN RESTORE-IMAGE ANYWAY")))
+    "From a freshly restarted Lisp image, restore the saved Lisp environment
+by setting appropriate variables, running various hooks, and calling any specified entry point.
+
+If the image has already been restored or is already being restored, as per *IMAGE-RESTORED-P*,
+call the IF-ALREADY-RESTORED error handler (by default, a continuable error), and do return
+immediately to the surrounding restore process if allowed to continue.
+
+Then, comes the restore process itself:
+First, call each function in the RESTORE-HOOK,
+in the order they were registered with REGISTER-IMAGE-RESTORE-HOOK.
+Second, evaluate the prelude, which is often Lisp text that is read,
+as per EVAL-INPUT.
+Third, call the ENTRY-POINT function, if any is specified, with no argument.
+
+The restore process happens in a WITH-FATAL-CONDITION-HANDLER, so that if LISP-INTERACTION is NIL,
+any unhandled error leads to a backtrace and an exit with an error status.
+If LISP-INTERACTION is NIL, the process also exits when no error occurs:
+if neither restart nor entry function is provided, the program will exit with status 0 (success);
+if a function was provided, the program will exit after the function returns (if it returns),
+with status 0 if and only if the primary return value of result is generalized boolean true,
+and with status 1 if this value is NIL.
+
+If LISP-INTERACTION is true, unhandled errors will take you to the debugger, and the result
+of the function will be returned rather than interpreted as a boolean designating an exit code."
+    (when *image-restored-p*
+      (if if-already-restored
+          (call-function if-already-restored "Image already ~:[being ~;~]restored"
+                         (eq *image-restored-p* t))
+          (return-from restore-image)))
+    (with-fatal-condition-handler ()
+      (setf *lisp-interaction* lisp-interaction)
+      (setf *image-restore-hook* restore-hook)
+      (setf *image-prelude* prelude)
+      (setf *image-restored-p* :in-progress)
+      (call-image-restore-hook)
+      (standard-eval-thunk prelude)
+      (setf *image-restored-p* t)
+      (let ((results (multiple-value-list
+                      (if entry-point
+                          (call-function entry-point)
+                          t))))
+        (if lisp-interaction
+            (values-list results)
+            (shell-boolean-exit (first results)))))))
+
+
+;;; Dumping an image
+
+(with-upgradability ()
+  (defun dump-image (filename &key output-name executable
+                                (postlude *image-postlude*)
+                                (dump-hook *image-dump-hook*)
+                                #+clozure prepend-symbols #+clozure (purify t)
+                                #+sbcl compression
+                                #+(and sbcl os-windows) application-type)
+    "Dump an image of the current Lisp environment at pathname FILENAME, with various options.
+
+First, finalize the image, by evaluating the POSTLUDE as per EVAL-INPUT, then calling each of
+ the functions in DUMP-HOOK, in reverse order of registration by REGISTER-IMAGE-DUMP-HOOK.
+
+If EXECUTABLE is true, create an standalone executable program that calls RESTORE-IMAGE on startup.
+
+Pass various implementation-defined options, such as PREPEND-SYMBOLS and PURITY on CCL,
+or COMPRESSION on SBCL, and APPLICATION-TYPE on SBCL/Windows."
+    ;; Note: at least SBCL saves only global values of variables in the heap image,
+    ;; so make sure things you want to dump are NOT just local bindings shadowing the global values.
+    (declare (ignorable filename output-name executable))
+    (setf *image-dumped-p* (if executable :executable t))
+    (setf *image-restored-p* :in-regress)
+    (setf *image-postlude* postlude)
+    (standard-eval-thunk *image-postlude*)
+    (setf *image-dump-hook* dump-hook)
+    (call-image-dump-hook)
+    (setf *image-restored-p* nil)
+    #-(or clisp clozure (and cmucl executable) lispworks sbcl scl)
+    (when executable
+      (not-implemented-error 'dump-image "dumping an executable"))
+    #+allegro
+    (progn
+      (sys:resize-areas :global-gc t :pack-heap t :sift-old-areas t :tenure t) ; :new 5000000
+      (excl:dumplisp :name filename :suppress-allegro-cl-banner t))
+    #+clisp
+    (apply #'ext:saveinitmem filename
+           :quiet t
+           :start-package *package*
+           :keep-global-handlers nil
+           ;; Faré explains the odd executable value (slightly paraphrased):
+           ;; 0 is very different from t in clisp and there for a good reason:
+           ;; 0 turns the executable into one that has its own command-line handling, so hackers can't
+           ;; use the underlying -i or -x to turn your would-be restricted binary into an unrestricted evaluator.
+           :executable (if executable 0 t) ;--- requires clisp 2.48 or later, still catches --clisp-x
+           (when executable
+             (list
+              ;; :parse-options nil ;--- requires a non-standard patch to clisp.
+              :norc t :script nil :init-function #'restore-image)))
+    #+clozure
+    (flet ((dump (prepend-kernel)
+             (ccl:save-application filename :prepend-kernel prepend-kernel :purify purify
+                                            :toplevel-function (when executable #'restore-image))))
+      ;;(setf ccl::*application* (make-instance 'ccl::lisp-development-system))
+      (if prepend-symbols
+          (with-temporary-file (:prefix "ccl-symbols-" :direction :output :pathname path)
+            (require 'elf)
+            (funcall (fdefinition 'ccl::write-elf-symbols-to-file) path)
+            (dump path))
+          (dump t)))
+    #+(or cmucl scl)
+    (progn
+      (ext:gc :full t)
+      (setf ext:*batch-mode* nil)
+      (setf ext::*gc-run-time* 0)
+      (apply 'ext:save-lisp filename
+             :allow-other-keys t ;; hush SCL and old versions of CMUCL
+             #+(and cmucl executable) :executable #+(and cmucl executable) t
+             (when executable '(:init-function restore-image :process-command-line nil
+                                :quiet t :load-init-file nil :site-init nil))))
+    #+gcl
+    (progn
+      (si::set-hole-size 500) (si::gbc nil) (si::sgc-on t)
+      (si::save-system filename))
+    #+lispworks
+    (if executable
+        (lispworks:deliver 'restore-image filename 0 :interface nil)
+        (hcl:save-image filename :environment nil))
+    #+sbcl
+    (progn
+      ;;(sb-pcl::precompile-random-code-segments) ;--- it is ugly slow at compile-time (!) when the initial core is a big CLOS program. If you want it, do it yourself
+      (setf sb-ext::*gc-run-time* 0)
+      (apply 'sb-ext:save-lisp-and-die filename
+             :executable t ;--- always include the runtime that goes with the core
+             (append
+              (when compression (list :compression compression))
+              ;;--- only save runtime-options for standalone executables
+              (when executable (list :toplevel #'restore-image :save-runtime-options t))
+              #+(and sbcl os-windows) ;; passing :application-type :gui will disable the console window.
+              ;; the default is :console - only works with SBCL 1.1.15 or later.
+              (when application-type (list :application-type application-type)))))
+    #-(or allegro clisp clozure cmucl gcl lispworks sbcl scl)
+    (not-implemented-error 'dump-image))
+
+  (defun create-image (destination lisp-object-files
+                       &key kind output-name prologue-code epilogue-code extra-object-files
+                         (prelude () preludep) (postlude () postludep)
+                         (entry-point () entry-point-p) build-args no-uiop)
+    (declare (ignorable destination lisp-object-files extra-object-files kind output-name
+                        prologue-code epilogue-code prelude preludep postlude postludep
+                        entry-point entry-point-p build-args no-uiop))
+    "On ECL, create an executable at pathname DESTINATION from the specified OBJECT-FILES and options"
+    ;; Is it meaningful to run these in the current environment?
+    ;; only if we also track the object files that constitute the "current" image,
+    ;; and otherwise simulate dump-image, including quitting at the end.
+    #-(or clasp ecl mkcl) (not-implemented-error 'create-image)
+    #+(or clasp ecl mkcl)
+    (let ((epilogue-code
+           (if no-uiop
+               epilogue-code
+               (let ((forms
+                      (append
+                       (when epilogue-code `(,epilogue-code))
+                       (when postludep `((setf *image-postlude* ',postlude)))
+                       (when preludep `((setf *image-prelude* ',prelude)))
+                       (when entry-point-p `((setf *image-entry-point* ',entry-point)))
+                       (case kind
+                         ((:image)
+                          (setf kind :program) ;; to ECL, it's just another program.
+                          `((setf *image-dumped-p* t)
+                            (si::top-level #+(or clasp ecl) t) (quit)))
+                         ((:program)
+                          `((setf *image-dumped-p* :executable)
+                            (shell-boolean-exit
+                             (restore-image))))))))
+                 (when forms `(progn ,@forms))))))
+      (check-type kind (member :dll :shared-library :lib :static-library
+                               :fasl :fasb :program))
+      (apply #+clasp 'cmp:builder #+clasp kind
+             #+(or ecl mkcl)
+             (ecase kind
+               ((:dll :shared-library)
+                #+ecl 'c::build-shared-library #+mkcl 'compiler:build-shared-library)
+               ((:lib :static-library)
+                #+ecl 'c::build-static-library #+mkcl 'compiler:build-static-library)
+               ((:fasl #+ecl :fasb)
+                #+ecl 'c::build-fasl #+mkcl 'compiler:build-fasl)
+               #+mkcl ((:fasb) 'compiler:build-bundle)
+               ((:program)
+                #+ecl 'c::build-program #+mkcl 'compiler:build-program))
+             (pathname destination)
+             #+(or clasp ecl) :lisp-files #+mkcl :lisp-object-files
+             (append lisp-object-files #+(or clasp ecl) extra-object-files)
+             #+ecl :init-name
+             #+ecl (getf build-args :init-name)
+             (append
+              (when prologue-code `(:prologue-code ,prologue-code))
+              (when epilogue-code `(:epilogue-code ,epilogue-code))
+              #+mkcl (when extra-object-files `(:object-files ,extra-object-files))
+              build-args)))))
+
+
+;;; Some universal image restore hooks
+(with-upgradability ()
+  (map () 'register-image-restore-hook
+       '(setup-stdin setup-stdout setup-stderr
+         setup-command-line-arguments setup-temporary-directory
+         #+abcl detect-os)))
+;;;; -------------------------------------------------------------------------
+;;;; Support to build (compile and load) Lisp files
+
+(uiop/package:define-package :uiop/lisp-build
+  (:nicknames :asdf/lisp-build) ;; OBSOLETE, used by slime/contrib/swank-asdf.lisp
+  (:use :uiop/common-lisp :uiop/package :uiop/utility
+   :uiop/os :uiop/pathname :uiop/filesystem :uiop/stream :uiop/image)
+  (:export
+   ;; Variables
+   #:*compile-file-warnings-behaviour* #:*compile-file-failure-behaviour*
+   #:*output-translation-function*
+   #:*optimization-settings* #:*previous-optimization-settings*
+   #:*base-build-directory*
+   #:compile-condition #:compile-file-error #:compile-warned-error #:compile-failed-error
+   #:compile-warned-warning #:compile-failed-warning
+   #:check-lisp-compile-results #:check-lisp-compile-warnings
+   #:*uninteresting-conditions* #:*usual-uninteresting-conditions*
+   #:*uninteresting-compiler-conditions* #:*uninteresting-loader-conditions*
+   ;; Types
+   #+sbcl #:sb-grovel-unknown-constant-condition
+   ;; Functions & Macros
+   #:get-optimization-settings #:proclaim-optimization-settings #:with-optimization-settings
+   #:call-with-muffled-compiler-conditions #:with-muffled-compiler-conditions
+   #:call-with-muffled-loader-conditions #:with-muffled-loader-conditions
+   #:reify-simple-sexp #:unreify-simple-sexp
+   #:reify-deferred-warnings #:unreify-deferred-warnings
+   #:reset-deferred-warnings #:save-deferred-warnings #:check-deferred-warnings
+   #:with-saved-deferred-warnings #:warnings-file-p #:warnings-file-type #:*warnings-file-type*
+   #:enable-deferred-warnings-check #:disable-deferred-warnings-check
+   #:current-lisp-file-pathname #:load-pathname
+   #:lispize-pathname #:compile-file-type #:call-around-hook
+   #:compile-file* #:compile-file-pathname* #:*compile-check*
+   #:load* #:load-from-string #:combine-fasls)
+  (:intern #:defaults #:failure-p #:warnings-p #:s #:y #:body))
+(in-package :uiop/lisp-build)
+
+(with-upgradability ()
+  (defvar *compile-file-warnings-behaviour*
+    (or #+clisp :ignore :warn)
+    "How should ASDF react if it encounters a warning when compiling a file?
+Valid values are :error, :warn, and :ignore.")
+
+  (defvar *compile-file-failure-behaviour*
+    (or #+(or mkcl sbcl) :error #+clisp :ignore :warn)
+    "How should ASDF react if it encounters a failure (per the ANSI spec of COMPILE-FILE)
+when compiling a file, which includes any non-style-warning warning.
+Valid values are :error, :warn, and :ignore.
+Note that ASDF ALWAYS raises an error if it fails to create an output file when compiling.")
+
+  (defvar *base-build-directory* nil
+    "When set to a non-null value, it should be an absolute directory pathname,
+which will serve as the *DEFAULT-PATHNAME-DEFAULTS* around a COMPILE-FILE,
+what more while the input-file is shortened if possible to ENOUGH-PATHNAME relative to it.
+This can help you produce more deterministic output for FASLs."))
+
+;;; Optimization settings
+(with-upgradability ()
+  (defvar *optimization-settings* nil
+    "Optimization settings to be used by PROCLAIM-OPTIMIZATION-SETTINGS")
+  (defvar *previous-optimization-settings* nil
+    "Optimization settings saved by PROCLAIM-OPTIMIZATION-SETTINGS")
+  (defparameter +optimization-variables+
+    ;; TODO: allegro genera corman mcl
+    (or #+(or abcl xcl) '(system::*speed* system::*space* system::*safety* system::*debug*)
+        #+clisp '() ;; system::*optimize* is a constant hash-table! (with non-constant contents)
+        #+clozure '(ccl::*nx-speed* ccl::*nx-space* ccl::*nx-safety*
+                    ccl::*nx-debug* ccl::*nx-cspeed*)
+        #+(or cmucl scl) '(c::*default-cookie*)
+        #+clasp nil
+        #+ecl (unless (use-ecl-byte-compiler-p) '(c::*speed* c::*space* c::*safety* c::*debug*))
+        #+gcl '(compiler::*speed* compiler::*space* compiler::*compiler-new-safety* compiler::*debug*)
+        #+lispworks '(compiler::*optimization-level*)
+        #+mkcl '(si::*speed* si::*space* si::*safety* si::*debug*)
+        #+sbcl '(sb-c::*policy*)))
+  (defun get-optimization-settings ()
+    "Get current compiler optimization settings, ready to PROCLAIM again"
+    #-(or abcl allegro clasp clisp clozure cmucl ecl lispworks mkcl sbcl scl xcl)
+    (warn "~S does not support ~S. Please help me fix that."
+          'get-optimization-settings (implementation-type))
+    #+clasp (cleavir-env:optimize (cleavir-env:optimize-info CLASP-CLEAVIR:*CLASP-ENV*))
+    #+(or abcl allegro clisp clozure cmucl ecl lispworks mkcl sbcl scl xcl)
+    (let ((settings '(speed space safety debug compilation-speed #+(or cmucl scl) c::brevity)))
+      #.`(loop #+(or allegro clozure)
+               ,@'(:with info = #+allegro (sys:declaration-information 'optimize)
+                   #+clozure (ccl:declaration-information 'optimize nil))
+               :for x :in settings
+               ,@(or #+(or abcl clasp ecl gcl mkcl xcl) '(:for v :in +optimization-variables+))
+               :for y = (or #+(or allegro clozure) (second (assoc x info)) ; normalize order
+                            #+clisp (gethash x system::*optimize* 1)
+                            #+(or abcl ecl mkcl xcl) (symbol-value v)
+                            #+(or cmucl scl) (slot-value c::*default-cookie*
+                                                       (case x (compilation-speed 'c::cspeed)
+                                                             (otherwise x)))
+                            #+lispworks (slot-value compiler::*optimization-level* x)
+                            #+sbcl (sb-c::policy-quality sb-c::*policy* x))
+               :when y :collect (list x y))))
+  (defun proclaim-optimization-settings ()
+    "Proclaim the optimization settings in *OPTIMIZATION-SETTINGS*"
+    (proclaim `(optimize ,@*optimization-settings*))
+    (let ((settings (get-optimization-settings)))
+      (unless (equal *previous-optimization-settings* settings)
+        (setf *previous-optimization-settings* settings))))
+  (defmacro with-optimization-settings ((&optional (settings *optimization-settings*)) &body body)
+    #+(or allegro clasp clisp)
+    (let ((previous-settings (gensym "PREVIOUS-SETTINGS"))
+          (reset-settings (gensym "RESET-SETTINGS")))
+      `(let* ((,previous-settings (get-optimization-settings))
+              (,reset-settings #+clasp (reverse ,previous-settings) #-clasp ,previous-settings))
+         ,@(when settings `((proclaim `(optimize ,@,settings))))
+         (unwind-protect (progn ,@body)
+           (proclaim `(optimize ,@,reset-settings)))))
+    #-(or allegro clasp clisp)
+    `(let ,(loop :for v :in +optimization-variables+ :collect `(,v ,v))
+       ,@(when settings `((proclaim `(optimize ,@,settings))))
+       ,@body)))
+
+
+;;; Condition control
+(with-upgradability ()
+  #+sbcl
+  (progn
+    (defun sb-grovel-unknown-constant-condition-p (c)
+      "Detect SB-GROVEL unknown-constant conditions on older versions of SBCL"
+      (ignore-errors
+       (and (typep c 'sb-int:simple-style-warning)
+            (string-enclosed-p
+             "Couldn't grovel for "
+             (simple-condition-format-control c)
+             " (unknown to the C compiler)."))))
+    (deftype sb-grovel-unknown-constant-condition ()
+      '(and style-warning (satisfies sb-grovel-unknown-constant-condition-p))))
+
+  (defvar *usual-uninteresting-conditions*
+    (append
+     ;;#+clozure '(ccl:compiler-warning)
+     #+cmucl '("Deleting unreachable code.")
+     #+lispworks '("~S being redefined in ~A (previously in ~A)."
+                   "~S defined more than once in ~A.") ;; lispworks gets confused by eval-when.
+     #+sbcl
+     '(sb-c::simple-compiler-note
+       "&OPTIONAL and &KEY found in the same lambda list: ~S"
+       sb-kernel:undefined-alien-style-warning
+       sb-grovel-unknown-constant-condition ; defined above.
+       sb-ext:implicit-generic-function-warning ;; Controversial.
+       sb-int:package-at-variance
+       sb-kernel:uninteresting-redefinition
+       ;; BEWARE: the below four are controversial to include here.
+       sb-kernel:redefinition-with-defun
+       sb-kernel:redefinition-with-defgeneric
+       sb-kernel:redefinition-with-defmethod
+       sb-kernel::redefinition-with-defmacro) ; not exported by old SBCLs
+     #+sbcl
+     (let ((condition (find-symbol* '#:lexical-environment-too-complex :sb-kernel nil)))
+       (when condition
+         (list condition)))
+     '("No generic function ~S present when encountering macroexpansion of defmethod. Assuming it will be an instance of standard-generic-function.")) ;; from closer2mop
+    "A suggested value to which to set or bind *uninteresting-conditions*.")
+
+  (defvar *uninteresting-conditions* '()
+    "Conditions that may be skipped while compiling or loading Lisp code.")
+  (defvar *uninteresting-compiler-conditions* '()
+    "Additional conditions that may be skipped while compiling Lisp code.")
+  (defvar *uninteresting-loader-conditions*
+    (append
+     '("Overwriting already existing readtable ~S." ;; from named-readtables
+       #(#:finalizers-off-warning :asdf-finalizers)) ;; from asdf-finalizers
+     #+clisp '(clos::simple-gf-replacing-method-warning))
+    "Additional conditions that may be skipped while loading Lisp code."))
+
+;;;; ----- Filtering conditions while building -----
+(with-upgradability ()
+  (defun call-with-muffled-compiler-conditions (thunk)
+    "Call given THUNK in a context where uninteresting conditions and compiler conditions are muffled"
+    (call-with-muffled-conditions
+     thunk (append *uninteresting-conditions* *uninteresting-compiler-conditions*)))
+  (defmacro with-muffled-compiler-conditions ((&optional) &body body)
+    "Trivial syntax for CALL-WITH-MUFFLED-COMPILER-CONDITIONS"
+    `(call-with-muffled-compiler-conditions #'(lambda () ,@body)))
+  (defun call-with-muffled-loader-conditions (thunk)
+    "Call given THUNK in a context where uninteresting conditions and loader conditions are muffled"
+    (call-with-muffled-conditions
+     thunk (append *uninteresting-conditions* *uninteresting-loader-conditions*)))
+  (defmacro with-muffled-loader-conditions ((&optional) &body body)
+    "Trivial syntax for CALL-WITH-MUFFLED-LOADER-CONDITIONS"
+    `(call-with-muffled-loader-conditions #'(lambda () ,@body))))
+
+
+;;;; Handle warnings and failures
+(with-upgradability ()
+  (define-condition compile-condition (condition)
+    ((context-format
+      :initform nil :reader compile-condition-context-format :initarg :context-format)
+     (context-arguments
+      :initform nil :reader compile-condition-context-arguments :initarg :context-arguments)
+     (description
+      :initform nil :reader compile-condition-description :initarg :description))
+    (:report (lambda (c s)
+               (format s (compatfmt "~@<~A~@[ while ~?~]~@:>")
+                       (or (compile-condition-description c) (type-of c))
+                       (compile-condition-context-format c)
+                       (compile-condition-context-arguments c)))))
+  (define-condition compile-file-error (compile-condition error) ())
+  (define-condition compile-warned-warning (compile-condition warning) ())
+  (define-condition compile-warned-error (compile-condition error) ())
+  (define-condition compile-failed-warning (compile-condition warning) ())
+  (define-condition compile-failed-error (compile-condition error) ())
+
+  (defun check-lisp-compile-warnings (warnings-p failure-p
+                                                  &optional context-format context-arguments)
+    "Given the warnings or failures as resulted from COMPILE-FILE or checking deferred warnings,
+raise an error or warning as appropriate"
+    (when failure-p
+      (case *compile-file-failure-behaviour*
+        (:warn (warn 'compile-failed-warning
+                     :description "Lisp compilation failed"
+                     :context-format context-format
+                     :context-arguments context-arguments))
+        (:error (error 'compile-failed-error
+                       :description "Lisp compilation failed"
+                       :context-format context-format
+                       :context-arguments context-arguments))
+        (:ignore nil)))
+    (when warnings-p
+      (case *compile-file-warnings-behaviour*
+        (:warn (warn 'compile-warned-warning
+                     :description "Lisp compilation had style-warnings"
+                     :context-format context-format
+                     :context-arguments context-arguments))
+        (:error (error 'compile-warned-error
+                       :description "Lisp compilation had style-warnings"
+                       :context-format context-format
+                       :context-arguments context-arguments))
+        (:ignore nil))))
+
+  (defun check-lisp-compile-results (output warnings-p failure-p
+                                             &optional context-format context-arguments)
+    "Given the results of COMPILE-FILE, raise an error or warning as appropriate"
+    (unless output
+      (error 'compile-file-error :context-format context-format :context-arguments context-arguments))
+    (check-lisp-compile-warnings warnings-p failure-p context-format context-arguments)))
+
+
+;;;; Deferred-warnings treatment, originally implemented by Douglas Katzman.
+;;;
+;;; To support an implementation, three functions must be implemented:
+;;; reify-deferred-warnings unreify-deferred-warnings reset-deferred-warnings
+;;; See their respective docstrings.
+(with-upgradability ()
+  (defun reify-simple-sexp (sexp)
+    "Given a simple SEXP, return a representation of it as a portable SEXP.
+Simple means made of symbols, numbers, characters, simple-strings, pathnames, cons cells."
+    (etypecase sexp
+      (symbol (reify-symbol sexp))
+      ((or number character simple-string pathname) sexp)
+      (cons (cons (reify-simple-sexp (car sexp)) (reify-simple-sexp (cdr sexp))))
+      (simple-vector (vector (mapcar 'reify-simple-sexp (coerce sexp 'list))))))
+
+  (defun unreify-simple-sexp (sexp)
+    "Given the portable output of REIFY-SIMPLE-SEXP, return the simple SEXP it represents"
+    (etypecase sexp
+      ((or symbol number character simple-string pathname) sexp)
+      (cons (cons (unreify-simple-sexp (car sexp)) (unreify-simple-sexp (cdr sexp))))
+      ((simple-vector 2) (unreify-symbol sexp))
+      ((simple-vector 1) (coerce (mapcar 'unreify-simple-sexp (aref sexp 0)) 'vector))))
+
+  #+clozure
+  (progn
+    (defun reify-source-note (source-note)
+      (when source-note
+        (with-accessors ((source ccl::source-note-source) (filename ccl:source-note-filename)
+                         (start-pos ccl:source-note-start-pos) (end-pos ccl:source-note-end-pos)) source-note
+          (declare (ignorable source))
+          (list :filename filename :start-pos start-pos :end-pos end-pos
+                #|:source (reify-source-note source)|#))))
+    (defun unreify-source-note (source-note)
+      (when source-note
+        (destructuring-bind (&key filename start-pos end-pos source) source-note
+          (ccl::make-source-note :filename filename :start-pos start-pos :end-pos end-pos
+                                 :source (unreify-source-note source)))))
+    (defun unsymbolify-function-name (name)
+      (if-let (setfed (gethash name ccl::%setf-function-name-inverses%))
+        `(setf ,setfed)
+        name))
+    (defun symbolify-function-name (name)
+      (if (and (consp name) (eq (first name) 'setf))
+          (let ((setfed (second name)))
+            (gethash setfed ccl::%setf-function-names%))
+          name))
+    (defun reify-function-name (function-name)
+      (let ((name (or (first function-name) ;; defun: extract the name
+                      (let ((sec (second function-name)))
+                        (or (and (atom sec) sec) ; scoped method: drop scope
+                            (first sec)))))) ; method: keep gf name, drop method specializers
+        (list name)))
+    (defun unreify-function-name (function-name)
+      function-name)
+    (defun nullify-non-literals (sexp)
+      (typecase sexp
+        ((or number character simple-string symbol pathname) sexp)
+        (cons (cons (nullify-non-literals (car sexp))
+                    (nullify-non-literals (cdr sexp))))
+        (t nil)))
+    (defun reify-deferred-warning (deferred-warning)
+      (with-accessors ((warning-type ccl::compiler-warning-warning-type)
+                       (args ccl::compiler-warning-args)
+                       (source-note ccl:compiler-warning-source-note)
+                       (function-name ccl:compiler-warning-function-name)) deferred-warning
+        (list :warning-type warning-type :function-name (reify-function-name function-name)
+              :source-note (reify-source-note source-note)
+              :args (destructuring-bind (fun &rest more)
+                        args
+                      (cons (unsymbolify-function-name fun)
+                            (nullify-non-literals more))))))
+    (defun unreify-deferred-warning (reified-deferred-warning)
+      (destructuring-bind (&key warning-type function-name source-note args)
+          reified-deferred-warning
+        (make-condition (or (cdr (ccl::assq warning-type ccl::*compiler-whining-conditions*))
+                            'ccl::compiler-warning)
+                        :function-name (unreify-function-name function-name)
+                        :source-note (unreify-source-note source-note)
+                        :warning-type warning-type
+                        :args (destructuring-bind (fun . more) args
+                                (cons (symbolify-function-name fun) more))))))
+  #+(or cmucl scl)
+  (defun reify-undefined-warning (warning)
+    ;; Extracting undefined-warnings from the compilation-unit
+    ;; To be passed through the above reify/unreify link, it must be a "simple-sexp"
+    (list*
+     (c::undefined-warning-kind warning)
+     (c::undefined-warning-name warning)
+     (c::undefined-warning-count warning)
+     (mapcar
+      #'(lambda (frob)
+          ;; the lexenv slot can be ignored for reporting purposes
+          `(:enclosing-source ,(c::compiler-error-context-enclosing-source frob)
+            :source ,(c::compiler-error-context-source frob)
+            :original-source ,(c::compiler-error-context-original-source frob)
+            :context ,(c::compiler-error-context-context frob)
+            :file-name ,(c::compiler-error-context-file-name frob) ; a pathname
+            :file-position ,(c::compiler-error-context-file-position frob) ; an integer
+            :original-source-path ,(c::compiler-error-context-original-source-path frob)))
+      (c::undefined-warning-warnings warning))))
+
+  #+sbcl
+  (defun reify-undefined-warning (warning)
+    ;; Extracting undefined-warnings from the compilation-unit
+    ;; To be passed through the above reify/unreify link, it must be a "simple-sexp"
+    (list*
+     (sb-c::undefined-warning-kind warning)
+     (sb-c::undefined-warning-name warning)
+     (sb-c::undefined-warning-count warning)
+     ;; the COMPILER-ERROR-CONTEXT struct has changed in SBCL, which means how we
+     ;; handle deferred warnings must change... TODO: when enough time has
+     ;; gone by, just assume all versions of SBCL are adequately
+     ;; up-to-date, and cut this material.[2018/05/30:rpg]
+     (mapcar
+      #'(lambda (frob)
+          ;; the lexenv slot can be ignored for reporting purposes
+          `(
+            #- #.(uiop/utility:symbol-test-to-feature-expression '#:compiler-error-context-%source '#:sb-c)
+            ,@`(:enclosing-source
+                ,(sb-c::compiler-error-context-enclosing-source frob)
+                :source
+                ,(sb-c::compiler-error-context-source frob)
+                :original-source
+                ,(sb-c::compiler-error-context-original-source frob))
+            #+ #.(uiop/utility:symbol-test-to-feature-expression '#:compiler-error-context-%source '#:sb-c)
+            ,@ `(:%enclosing-source
+                 ,(sb-c::compiler-error-context-enclosing-source frob)
+                 :%source
+                 ,(sb-c::compiler-error-context-source frob)
+                 :original-form
+                 ,(sb-c::compiler-error-context-original-form frob))
+            :context ,(sb-c::compiler-error-context-context frob)
+            :file-name ,(sb-c::compiler-error-context-file-name frob) ; a pathname
+            :file-position ,(sb-c::compiler-error-context-file-position frob) ; an integer
+            :original-source-path ,(sb-c::compiler-error-context-original-source-path frob)))
+      (sb-c::undefined-warning-warnings warning))))
+
+  (defun reify-deferred-warnings ()
+    "return a portable S-expression, portably readable and writeable in any Common Lisp implementation
+using READ within a WITH-SAFE-IO-SYNTAX, that represents the warnings currently deferred by
+WITH-COMPILATION-UNIT. One of three functions required for deferred-warnings support in ASDF."
+    #+allegro
+    (list :functions-defined excl::.functions-defined.
+          :functions-called excl::.functions-called.)
+    #+clozure
+    (mapcar 'reify-deferred-warning
+            (if-let (dw ccl::*outstanding-deferred-warnings*)
+              (let ((mdw (ccl::ensure-merged-deferred-warnings dw)))
+                (ccl::deferred-warnings.warnings mdw))))
+    #+(or cmucl scl)
+    (when lisp::*in-compilation-unit*
+      ;; Try to send nothing through the pipe if nothing needs to be accumulated
+      `(,@(when c::*undefined-warnings*
+            `((c::*undefined-warnings*
+               ,@(mapcar #'reify-undefined-warning c::*undefined-warnings*))))
+        ,@(loop :for what :in '(c::*compiler-error-count*
+                                c::*compiler-warning-count*
+                                c::*compiler-note-count*)
+                :for value = (symbol-value what)
+                :when (plusp value)
+                  :collect `(,what . ,value))))
+    #+sbcl
+    (when sb-c::*in-compilation-unit*
+      ;; Try to send nothing through the pipe if nothing needs to be accumulated
+      `(,@(when sb-c::*undefined-warnings*
+            `((sb-c::*undefined-warnings*
+               ,@(mapcar #'reify-undefined-warning sb-c::*undefined-warnings*))))
+        ,@(loop :for what :in '(sb-c::*aborted-compilation-unit-count*
+                                sb-c::*compiler-error-count*
+                                sb-c::*compiler-warning-count*
+                                sb-c::*compiler-style-warning-count*
+                                sb-c::*compiler-note-count*)
+                :for value = (symbol-value what)
+                :when (plusp value)
+                  :collect `(,what . ,value)))))
+
+  (defun unreify-deferred-warnings (reified-deferred-warnings)
+    "given a S-expression created by REIFY-DEFERRED-WARNINGS, reinstantiate the corresponding
+deferred warnings as to be handled at the end of the current WITH-COMPILATION-UNIT.
+Handle any warning that has been resolved already,
+such as an undefined function that has been defined since.
+One of three functions required for deferred-warnings support in ASDF."
+    (declare (ignorable reified-deferred-warnings))
+    #+allegro
+    (destructuring-bind (&key functions-defined functions-called)
+        reified-deferred-warnings
+      (setf excl::.functions-defined.
+            (append functions-defined excl::.functions-defined.)
+            excl::.functions-called.
+            (append functions-called excl::.functions-called.)))
+    #+clozure
+    (let ((dw (or ccl::*outstanding-deferred-warnings*
+                  (setf ccl::*outstanding-deferred-warnings* (ccl::%defer-warnings t)))))
+      (appendf (ccl::deferred-warnings.warnings dw)
+               (mapcar 'unreify-deferred-warning reified-deferred-warnings)))
+    #+(or cmucl scl)
+    (dolist (item reified-deferred-warnings)
+      ;; Each item is (symbol . adjustment) where the adjustment depends on the symbol.
+      ;; For *undefined-warnings*, the adjustment is a list of initargs.
+      ;; For everything else, it's an integer.
+      (destructuring-bind (symbol . adjustment) item
+        (case symbol
+          ((c::*undefined-warnings*)
+           (setf c::*undefined-warnings*
+                 (nconc (mapcan
+                         #'(lambda (stuff)
+                             (destructuring-bind (kind name count . rest) stuff
+                               (unless (case kind (:function (fboundp name)))
+                                 (list
+                                  (c::make-undefined-warning
+                                   :name name
+                                   :kind kind
+                                   :count count
+                                   :warnings
+                                   (mapcar #'(lambda (x)
+                                               (apply #'c::make-compiler-error-context x))
+                                           rest))))))
+                         adjustment)
+                        c::*undefined-warnings*)))
+          (otherwise
+           (set symbol (+ (symbol-value symbol) adjustment))))))
+    #+sbcl
+    (dolist (item reified-deferred-warnings)
+      ;; Each item is (symbol . adjustment) where the adjustment depends on the symbol.
+      ;; For *undefined-warnings*, the adjustment is a list of initargs.
+      ;; For everything else, it's an integer.
+      (destructuring-bind (symbol . adjustment) item
+        (case symbol
+          ((sb-c::*undefined-warnings*)
+           (setf sb-c::*undefined-warnings*
+                 (nconc (mapcan
+                         #'(lambda (stuff)
+                             (destructuring-bind (kind name count . rest) stuff
+                               (unless (case kind (:function (fboundp name)))
+                                 (list
+                                  (sb-c::make-undefined-warning
+                                   :name name
+                                   :kind kind
+                                   :count count
+                                   :warnings
+                                   (mapcar #'(lambda (x)
+                                               (apply #'sb-c::make-compiler-error-context x))
+                                           rest))))))
+                         adjustment)
+                        sb-c::*undefined-warnings*)))
+          (otherwise
+           (set symbol (+ (symbol-value symbol) adjustment)))))))
+
+  (defun reset-deferred-warnings ()
+    "Reset the set of deferred warnings to be handled at the end of the current WITH-COMPILATION-UNIT.
+One of three functions required for deferred-warnings support in ASDF."
+    #+allegro
+    (setf excl::.functions-defined. nil
+          excl::.functions-called. nil)
+    #+clozure
+    (if-let (dw ccl::*outstanding-deferred-warnings*)
+      (let ((mdw (ccl::ensure-merged-deferred-warnings dw)))
+        (setf (ccl::deferred-warnings.warnings mdw) nil)))
+    #+(or cmucl scl)
+    (when lisp::*in-compilation-unit*
+      (setf c::*undefined-warnings* nil
+            c::*compiler-error-count* 0
+            c::*compiler-warning-count* 0
+            c::*compiler-note-count* 0))
+    #+sbcl
+    (when sb-c::*in-compilation-unit*
+      (setf sb-c::*undefined-warnings* nil
+            sb-c::*aborted-compilation-unit-count* 0
+            sb-c::*compiler-error-count* 0
+            sb-c::*compiler-warning-count* 0
+            sb-c::*compiler-style-warning-count* 0
+            sb-c::*compiler-note-count* 0)))
+
+  (defun save-deferred-warnings (warnings-file)
+    "Save forward reference conditions so they may be issued at a latter time,
+possibly in a different process."
+    (with-open-file (s warnings-file :direction :output :if-exists :supersede
+                       :element-type *default-stream-element-type*
+                       :external-format *utf-8-external-format*)
+      (with-safe-io-syntax ()
+        (let ((*read-eval* t))
+          (write (reify-deferred-warnings) :stream s :pretty t :readably t))
+        (terpri s))))
+
+  (defun warnings-file-type (&optional implementation-type)
+    "The pathname type for warnings files on given IMPLEMENTATION-TYPE,
+where NIL designates the current one"
+    (case (or implementation-type *implementation-type*)
+      ((:acl :allegro) "allegro-warnings")
+      ;;((:clisp) "clisp-warnings")
+      ((:cmu :cmucl) "cmucl-warnings")
+      ((:sbcl) "sbcl-warnings")
+      ((:clozure :ccl) "ccl-warnings")
+      ((:scl) "scl-warnings")))
+
+  (defvar *warnings-file-type* nil
+    "Pathname type for warnings files, or NIL if disabled")
+
+  (defun enable-deferred-warnings-check ()
+    "Enable the saving of deferred warnings"
+    (setf *warnings-file-type* (warnings-file-type)))
+
+  (defun disable-deferred-warnings-check ()
+    "Disable the saving of deferred warnings"
+    (setf *warnings-file-type* nil))
+
+  (defun warnings-file-p (file &optional implementation-type)
+    "Is FILE a saved warnings file for the given IMPLEMENTATION-TYPE?
+If that given type is NIL, use the currently configured *WARNINGS-FILE-TYPE* instead."
+    (if-let (type (if implementation-type
+                      (warnings-file-type implementation-type)
+                      *warnings-file-type*))
+      (equal (pathname-type file) type)))
+
+  (defun check-deferred-warnings (files &optional context-format context-arguments)
+    "Given a list of FILES containing deferred warnings saved by CALL-WITH-SAVED-DEFERRED-WARNINGS,
+re-intern and raise any warnings that are still meaningful."
+    (let ((file-errors nil)
+          (failure-p nil)
+          (warnings-p nil))
+      (handler-bind
+          ((warning #'(lambda (c)
+                        (setf warnings-p t)
+                        (unless (typep c 'style-warning)
+                          (setf failure-p t)))))
+        (with-compilation-unit (:override t)
+          (reset-deferred-warnings)
+          (dolist (file files)
+            (unreify-deferred-warnings
+             (handler-case
+                 (with-safe-io-syntax ()
+                   (let ((*read-eval* t))
+                     (read-file-form file)))
+               (error (c)
+                 ;;(delete-file-if-exists file) ;; deleting forces rebuild but prevents debugging
+                 (push c file-errors)
+                 nil))))))
+      (dolist (error file-errors) (error error))
+      (check-lisp-compile-warnings
+       (or failure-p warnings-p) failure-p context-format context-arguments)))
+
+  #|
+  Mini-guide to adding support for deferred warnings on an implementation.
+
+  First, look at what such a warning looks like:
+
+  (describe
+  (handler-case
+  (and (eval '(lambda () (some-undefined-function))) nil)
+  (t (c) c)))
+
+  Then you can grep for the condition type in your compiler sources
+  and see how to catch those that have been deferred,
+  and/or read, clear and restore the deferred list.
+
+  Also look at
+  (macroexpand-1 '(with-compilation-unit () foo))
+  |#
+
+  (defun call-with-saved-deferred-warnings (thunk warnings-file &key source-namestring)
+    "If WARNINGS-FILE is not nil, record the deferred-warnings around a call to THUNK
+and save those warnings to the given file for latter use,
+possibly in a different process. Otherwise just call THUNK."
+    (declare (ignorable source-namestring))
+    (if warnings-file
+        (with-compilation-unit (:override t #+sbcl :source-namestring #+sbcl source-namestring)
+          (unwind-protect
+               (let (#+sbcl (sb-c::*undefined-warnings* nil))
+                 (multiple-value-prog1
+                     (funcall thunk)
+                   (save-deferred-warnings warnings-file)))
+            (reset-deferred-warnings)))
+        (funcall thunk)))
+
+  (defmacro with-saved-deferred-warnings ((warnings-file &key source-namestring) &body body)
+    "Trivial syntax for CALL-WITH-SAVED-DEFERRED-WARNINGS"
+    `(call-with-saved-deferred-warnings
+      #'(lambda () ,@body) ,warnings-file :source-namestring ,source-namestring)))
+
+
+;;; from ASDF
+(with-upgradability ()
+  (defun current-lisp-file-pathname ()
+    "Portably return the PATHNAME of the current Lisp source file being compiled or loaded"
+    (or *compile-file-pathname* *load-pathname*))
+
+  (defun load-pathname ()
+    "Portably return the LOAD-PATHNAME of the current source file or fasl.
+    May return a relative pathname."
+    *load-pathname*) ;; magic no longer needed for GCL.
+
+  (defun lispize-pathname (input-file)
+    "From a INPUT-FILE pathname, return a corresponding .lisp source pathname"
+    (make-pathname :type "lisp" :defaults input-file))
+
+  (defun compile-file-type (&rest keys)
+    "pathname TYPE for lisp FASt Loading files"
+    (declare (ignorable keys))
+    #-(or clasp ecl mkcl) (load-time-value (pathname-type (compile-file-pathname "foo.lisp")))
+    #+(or clasp ecl mkcl) (pathname-type (apply 'compile-file-pathname "foo" keys)))
+
+  (defun call-around-hook (hook function)
+    "Call a HOOK around the execution of FUNCTION"
+    (call-function (or hook 'funcall) function))
+
+  (defun compile-file-pathname* (input-file &rest keys &key output-file &allow-other-keys)
+    "Variant of COMPILE-FILE-PATHNAME that works well with COMPILE-FILE*"
+    (let* ((keys
+             (remove-plist-keys `(#+(or (and allegro (not (version>= 8 2)))) :external-format
+                                    ,@(unless output-file '(:output-file))) keys)))
+      (if (absolute-pathname-p output-file)
+          ;; what cfp should be doing, w/ mp* instead of mp
+          (let* ((type (pathname-type (apply 'compile-file-type keys)))
+                 (defaults (make-pathname
+                            :type type :defaults (merge-pathnames* input-file))))
+            (merge-pathnames* output-file defaults))
+          (funcall *output-translation-function*
+                   (apply 'compile-file-pathname input-file keys)))))
+
+  (defvar *compile-check* nil
+    "A hook for user-defined compile-time invariants")
+
+  (defun compile-file* (input-file &rest keys
+                                      &key (compile-check *compile-check*) output-file warnings-file
+                                      #+clisp lib-file #+(or clasp ecl mkcl) object-file #+sbcl emit-cfasl
+                                      &allow-other-keys)
+    "This function provides a portable wrapper around COMPILE-FILE.
+It ensures that the OUTPUT-FILE value is only returned and
+the file only actually created if the compilation was successful,
+even though your implementation may not do that. It also checks an optional
+user-provided consistency function COMPILE-CHECK to determine success;
+it will call this function if not NIL at the end of the compilation
+with the arguments sent to COMPILE-FILE*, except with :OUTPUT-FILE TMP-FILE
+where TMP-FILE is the name of a temporary output-file.
+It also checks two flags (with legacy british spelling from ASDF1),
+*COMPILE-FILE-FAILURE-BEHAVIOUR* and *COMPILE-FILE-WARNINGS-BEHAVIOUR*
+with appropriate implementation-dependent defaults,
+and if a failure (respectively warnings) are reported by COMPILE-FILE,
+it will consider that an error unless the respective behaviour flag
+is one of :SUCCESS :WARN :IGNORE.
+If WARNINGS-FILE is defined, deferred warnings are saved to that file.
+On ECL or MKCL, it creates both the linkable object and loadable fasl files.
+On implementations that erroneously do not recognize standard keyword arguments,
+it will filter them appropriately."
+    #+(or clasp ecl)
+    (when (and object-file (equal (compile-file-type) (pathname object-file)))
+      (format t "Whoa, some funky ASDF upgrade switched ~S calling convention for ~S and ~S~%"
+              'compile-file* output-file object-file)
+      (rotatef output-file object-file))
+    (let* ((keywords (remove-plist-keys
+                      `(:output-file :compile-check :warnings-file
+                                     #+clisp :lib-file #+(or clasp ecl mkcl) :object-file) keys))
+           (output-file
+             (or output-file
+                 (apply 'compile-file-pathname* input-file :output-file output-file keywords)))
+           (physical-output-file (physicalize-pathname output-file))
+           #+(or clasp ecl)
+           (object-file
+             (unless (use-ecl-byte-compiler-p)
+               (or object-file
+                   #+ecl (compile-file-pathname output-file :type :object)
+                   #+clasp (compile-file-pathname output-file :output-type :object))))
+           #+mkcl
+           (object-file
+             (or object-file
+                 (compile-file-pathname output-file :fasl-p nil)))
+           (tmp-file (tmpize-pathname physical-output-file))
+           #+clasp
+           (tmp-object-file (compile-file-pathname tmp-file :output-type :object))
+           #+sbcl
+           (cfasl-file (etypecase emit-cfasl
+                         (null nil)
+                         ((eql t) (make-pathname :type "cfasl" :defaults physical-output-file))
+                         (string (parse-namestring emit-cfasl))
+                         (pathname emit-cfasl)))
+           #+sbcl
+           (tmp-cfasl (when cfasl-file (make-pathname :type "cfasl" :defaults tmp-file)))
+           #+clisp
+           (tmp-lib (make-pathname :type "lib" :defaults tmp-file)))
+      (multiple-value-bind (output-truename warnings-p failure-p)
+          (with-enough-pathname (input-file :defaults *base-build-directory*)
+            (with-saved-deferred-warnings (warnings-file :source-namestring (namestring input-file))
+              (with-muffled-compiler-conditions ()
+                (or #-(or clasp ecl mkcl)
+                    (let (#+genera (si:*common-lisp-syntax-is-ansi-common-lisp* t))
+                      (apply 'compile-file input-file :output-file tmp-file
+                             #+sbcl (if emit-cfasl (list* :emit-cfasl tmp-cfasl keywords) keywords)
+                             #-sbcl keywords))
+                    #+ecl (apply 'compile-file input-file :output-file
+                                (if object-file
+                                    (list* object-file :system-p t keywords)
+                                    (list* tmp-file keywords)))
+                    #+clasp (apply 'compile-file input-file :output-file
+                                  (if object-file
+                                      (list* tmp-object-file :output-type :object #|:system-p t|# keywords)
+                                      (list* tmp-file keywords)))
+                    #+mkcl (apply 'compile-file input-file
+                                  :output-file object-file :fasl-p nil keywords)))))
+        (cond
+          ((and output-truename
+                (flet ((check-flag (flag behaviour)
+                         (or (not flag) (member behaviour '(:success :warn :ignore)))))
+                  (and (check-flag failure-p *compile-file-failure-behaviour*)
+                       (check-flag warnings-p *compile-file-warnings-behaviour*)))
+                (progn
+                  #+(or clasp ecl mkcl)
+                  (when (and #+(or clasp ecl) object-file)
+                    (setf output-truename
+                          (compiler::build-fasl tmp-file
+                           #+(or clasp ecl) :lisp-files #+mkcl :lisp-object-files (list #+clasp tmp-object-file #-clasp object-file))))
+                  (or (not compile-check)
+                      (apply compile-check input-file
+                             :output-file output-truename
+                             keywords))))
+           (delete-file-if-exists physical-output-file)
+           (when output-truename
+             ;; see CLISP bug 677
+             #+clisp
+             (progn
+               (setf tmp-lib (make-pathname :type "lib" :defaults output-truename))
+               (unless lib-file (setf lib-file (make-pathname :type "lib" :defaults physical-output-file)))
+               (rename-file-overwriting-target tmp-lib lib-file))
+             #+sbcl (when cfasl-file (rename-file-overwriting-target tmp-cfasl cfasl-file))
+             #+clasp
+             (progn
+               ;;; the following 4 rename-file-overwriting-target better be atomic, but we can't implement this right now
+               #+:target-os-darwin
+               (let ((temp-dwarf (pathname (strcat (namestring output-truename) ".dwarf")))
+                     (target-dwarf (pathname (strcat (namestring physical-output-file) ".dwarf"))))
+                 (when (probe-file temp-dwarf)
+                   (rename-file-overwriting-target temp-dwarf target-dwarf)))
+               ;;; need to rename the bc or ll file as well or test-bundle.script fails
+               ;;; They might not exist with parallel compilation
+               (let ((bitcode-src (compile-file-pathname tmp-file :output-type :bitcode))
+                     (bitcode-target (compile-file-pathname physical-output-file :output-type :bitcode)))
+                 (when (probe-file bitcode-src)
+                   (rename-file-overwriting-target bitcode-src bitcode-target)))
+               (rename-file-overwriting-target tmp-object-file object-file))
+             (rename-file-overwriting-target output-truename physical-output-file)
+             (setf output-truename (truename physical-output-file)))
+           #+clasp (delete-file-if-exists tmp-file)
+           #+clisp (progn (delete-file-if-exists tmp-file) ;; this one works around clisp BUG 677
+                          (delete-file-if-exists tmp-lib))) ;; this one is "normal" defensive cleanup
+          (t ;; error or failed check
+           (delete-file-if-exists output-truename)
+           #+clisp (delete-file-if-exists tmp-lib)
+           #+sbcl (delete-file-if-exists tmp-cfasl)
+           (setf output-truename nil)))
+        (values output-truename warnings-p failure-p))))
+
+  (defun load* (x &rest keys &key &allow-other-keys)
+    "Portable wrapper around LOAD that properly handles loading from a stream."
+    (with-muffled-loader-conditions ()
+      (let (#+genera (si:*common-lisp-syntax-is-ansi-common-lisp* t))
+        (etypecase x
+          ((or pathname string #-(or allegro clozure genera) stream #+clozure file-stream)
+           (apply 'load x keys))
+          ;; Genera can't load from a string-input-stream
+          ;; ClozureCL 1.6 can only load from file input stream
+          ;; Allegro 5, I don't remember but it must have been broken when I tested.
+          #+(or allegro clozure genera)
+          (stream ;; make do this way
+           (let ((*package* *package*)
+                 (*readtable* *readtable*)
+                 (*load-pathname* nil)
+                 (*load-truename* nil))
+             (eval-input x)))))))
+
+  (defun load-from-string (string)
+    "Portably read and evaluate forms from a STRING."
+    (with-input-from-string (s string) (load* s))))
+
+;;; Links FASLs together
+(with-upgradability ()
+  (defun combine-fasls (inputs output)
+    "Combine a list of FASLs INPUTS into a single FASL OUTPUT"
+    #-(or abcl allegro clisp clozure cmucl lispworks sbcl scl xcl)
+    (not-implemented-error 'combine-fasls "~%inputs: ~S~%output: ~S" inputs output)
+    #+abcl (funcall 'sys::concatenate-fasls inputs output) ; requires ABCL 1.2.0
+    #+(or allegro clisp cmucl sbcl scl xcl) (concatenate-files inputs output)
+    #+clozure (ccl:fasl-concatenate output inputs :if-exists :supersede)
+    #+lispworks
+    (let (fasls)
+      (unwind-protect
+           (progn
+             (loop :for i :in inputs
+                   :for n :from 1
+                   :for f = (add-pathname-suffix
+                             output (format nil "-FASL~D" n))
+                   :do (copy-file i f)
+                       (push f fasls))
+             (ignore-errors (lispworks:delete-system :fasls-to-concatenate))
+             (eval `(scm:defsystem :fasls-to-concatenate
+                      (:default-pathname ,(pathname-directory-pathname output))
+                      :members
+                      ,(loop :for f :in (reverse fasls)
+                             :collect `(,(namestring f) :load-only t))))
+             (scm:concatenate-system output :fasls-to-concatenate :force t))
+        (loop :for f :in fasls :do (ignore-errors (delete-file f)))
+        (ignore-errors (lispworks:delete-system :fasls-to-concatenate))))))
+;;;; -------------------------------------------------------------------------
+;;;; launch-program - semi-portably spawn asynchronous subprocesses
+
+(uiop/package:define-package :uiop/launch-program
+  (:use :uiop/common-lisp :uiop/package :uiop/utility
+   :uiop/pathname :uiop/os :uiop/filesystem :uiop/stream
+   :uiop/version)
+  (:export
+   ;;; Escaping the command invocation madness
+   #:easy-sh-character-p #:escape-sh-token #:escape-sh-command
+   #:escape-windows-token #:escape-windows-command
+   #:escape-shell-token #:escape-shell-command
+   #:escape-token #:escape-command
+
+   ;;; launch-program
+   #:launch-program
+   #:close-streams #:process-alive-p #:terminate-process #:wait-process
+   #:process-info-error-output #:process-info-input #:process-info-output #:process-info-pid))
+(in-package :uiop/launch-program)
+
+;;;; ----- Escaping strings for the shell -----
+(with-upgradability ()
+  (defun requires-escaping-p (token &key good-chars bad-chars)
+    "Does this token require escaping, given the specification of
+either good chars that don't need escaping or bad chars that do need escaping,
+as either a recognizing function or a sequence of characters."
+    (some
+     (cond
+       ((and good-chars bad-chars)
+        (parameter-error "~S: only one of good-chars and bad-chars can be provided"
+                         'requires-escaping-p))
+       ((typep good-chars 'function)
+        (complement good-chars))
+       ((typep bad-chars 'function)
+        bad-chars)
+       ((and good-chars (typep good-chars 'sequence))
+        #'(lambda (c) (not (find c good-chars))))
+       ((and bad-chars (typep bad-chars 'sequence))
+        #'(lambda (c) (find c bad-chars)))
+       (t (parameter-error "~S: no good-char criterion" 'requires-escaping-p)))
+     token))
+
+  (defun escape-token (token &key stream quote good-chars bad-chars escaper)
+    "Call the ESCAPER function on TOKEN string if it needs escaping as per
+REQUIRES-ESCAPING-P using GOOD-CHARS and BAD-CHARS, otherwise output TOKEN,
+using STREAM as output (or returning result as a string if NIL)"
+    (if (requires-escaping-p token :good-chars good-chars :bad-chars bad-chars)
+        (with-output (stream)
+          (apply escaper token stream (when quote `(:quote ,quote))))
+        (output-string token stream)))
+
+  (defun escape-windows-token-within-double-quotes (x &optional s)
+    "Escape a string token X within double-quotes
+for use within a MS Windows command-line, outputing to S."
+    (labels ((issue (c) (princ c s))
+             (issue-backslash (n) (loop :repeat n :do (issue #\\))))
+      (loop
+        :initially (issue #\") :finally (issue #\")
+        :with l = (length x) :with i = 0
+        :for i+1 = (1+ i) :while (< i l) :do
+          (case (char x i)
+            ((#\") (issue-backslash 1) (issue #\") (setf i i+1))
+            ((#\\)
+             (let* ((j (and (< i+1 l) (position-if-not
+                                       #'(lambda (c) (eql c #\\)) x :start i+1)))
+                    (n (- (or j l) i)))
+               (cond
+                 ((null j)
+                  (issue-backslash (* 2 n)) (setf i l))
+                 ((and (< j l) (eql (char x j) #\"))
+                  (issue-backslash (1+ (* 2 n))) (issue #\") (setf i (1+ j)))
+                 (t
+                  (issue-backslash n) (setf i j)))))
+            (otherwise
+             (issue (char x i)) (setf i i+1))))))
+
+  (defun easy-windows-character-p (x)
+    "Is X an \"easy\" character that does not require quoting by the shell?"
+    (or (alphanumericp x) (find x "+-_.,@:/=")))
+
+  (defun escape-windows-token (token &optional s)
+    "Escape a string TOKEN within double-quotes if needed
+for use within a MS Windows command-line, outputing to S."
+    (escape-token token :stream s :good-chars #'easy-windows-character-p :quote nil
+                        :escaper 'escape-windows-token-within-double-quotes))
+
+  (defun escape-sh-token-within-double-quotes (x s &key (quote t))
+    "Escape a string TOKEN within double-quotes
+for use within a POSIX Bourne shell, outputing to S;
+omit the outer double-quotes if key argument :QUOTE is NIL"
+    (when quote (princ #\" s))
+    (loop :for c :across x :do
+      (when (find c "$`\\\"") (princ #\\ s))
+      (princ c s))
+    (when quote (princ #\" s)))
+
+  (defun easy-sh-character-p (x)
+    "Is X an \"easy\" character that does not require quoting by the shell?"
+    (or (alphanumericp x) (find x "+-_.,%@:/=")))
+
+  (defun escape-sh-token (token &optional s)
+    "Escape a string TOKEN within double-quotes if needed
+for use within a POSIX Bourne shell, outputing to S."
+    (escape-token token :stream s :quote #\" :good-chars #'easy-sh-character-p
+                        :escaper 'escape-sh-token-within-double-quotes))
+
+  (defun escape-shell-token (token &optional s)
+    "Escape a token for the current operating system shell"
+    (os-cond
+      ((os-unix-p) (escape-sh-token token s))
+      ((os-windows-p) (escape-windows-token token s))))
+
+  (defun escape-command (command &optional s
+                                  (escaper 'escape-shell-token))
+    "Given a COMMAND as a list of tokens, return a string of the
+spaced, escaped tokens, using ESCAPER to escape."
+    (etypecase command
+      (string (output-string command s))
+      (list (with-output (s)
+              (loop :for first = t :then nil :for token :in command :do
+                (unless first (princ #\space s))
+                (funcall escaper token s))))))
+
+  (defun escape-windows-command (command &optional s)
+    "Escape a list of command-line arguments into a string suitable for parsing
+by CommandLineToArgv in MS Windows"
+    ;; http://msdn.microsoft.com/en-us/library/bb776391(v=vs.85).aspx
+    ;; http://msdn.microsoft.com/en-us/library/17w5ykft(v=vs.85).aspx
+    (escape-command command s 'escape-windows-token))
+
+  (defun escape-sh-command (command &optional s)
+    "Escape a list of command-line arguments into a string suitable for parsing
+by /bin/sh in POSIX"
+    (escape-command command s 'escape-sh-token))
+
+  (defun escape-shell-command (command &optional stream)
+    "Escape a command for the current operating system's shell"
+    (escape-command command stream 'escape-shell-token)))
+
+
+(with-upgradability ()
+  ;;; Internal helpers for run-program
+  (defun %normalize-io-specifier (specifier &optional role)
+    "Normalizes a portable I/O specifier for LAUNCH-PROGRAM into an implementation-dependent
+argument to pass to the internal RUN-PROGRAM"
+    (declare (ignorable role))
+    (typecase specifier
+      (null (or #+(or allegro lispworks) (null-device-pathname)))
+      (string (parse-native-namestring specifier))
+      (pathname specifier)
+      (stream specifier)
+      ((eql :stream) :stream)
+      ((eql :interactive)
+       #+(or allegro lispworks) nil
+       #+clisp :terminal
+       #+(or abcl clozure cmucl ecl mkcl sbcl scl) t
+       #-(or abcl clozure cmucl ecl mkcl sbcl scl allegro lispworks clisp)
+       (not-implemented-error :interactive-output
+                              "On this lisp implementation, cannot interpret ~a value of ~a"
+                              specifier role))
+      ((eql :output)
+       (cond ((eq role :error-output)
+              #+(or abcl allegro clozure cmucl ecl lispworks mkcl sbcl scl)
+              :output
+              #-(or abcl allegro clozure cmucl ecl lispworks mkcl sbcl scl)
+              (not-implemented-error :error-output-redirect
+                                     "Can't send ~a to ~a on this lisp implementation."
+                                     role specifier))
+             (t (parameter-error "~S IO specifier invalid for ~S" specifier role))))
+      ((eql t)
+       #+ (or lispworks abcl)
+       (not-implemented-error :interactive-output
+                              "On this lisp implementation, cannot interpret ~a value of ~a"
+                              specifier role)
+       #- (or lispworks abcl)
+       (cond ((eq role :error-output) *error-output*)
+             ((eq role :output) #+lispworks *terminal-io* #-lispworks *standard-output*)
+             ((eq role :input) *standard-input*)))
+      (otherwise
+       (parameter-error "Incorrect I/O specifier ~S for ~S"
+                        specifier role))))
+
+  (defun %interactivep (input output error-output)
+    (member :interactive (list input output error-output)))
+
+  (defun %signal-to-exit-code (signum)
+    (+ 128 signum))
+
+  (defun %code-to-status (exit-code signal-code)
+    (cond ((null exit-code) :running)
+          ((null signal-code) (values :exited exit-code))
+          (t (values :signaled signal-code))))
+
+  #+mkcl
+  (defun %mkcl-signal-to-number (signal)
+    (require :mk-unix)
+    (symbol-value (find-symbol signal :mk-unix)))
+
+  (defclass process-info ()
+    (;; The process field is highly platform-, implementation-, and
+     ;; even version-dependent.
+     ;; Prior to LispWorks 7, the only information that
+     ;; `sys:run-shell-command` with `:wait nil` was certain to return
+     ;; is a PID (e.g. when all streams are nil), hence we stored it
+     ;; and used `sys:pid-exit-status` to obtain an exit status
+     ;; later. That is still what we do.
+     ;; From LispWorks 7 on, if `sys:run-shell-command` does not
+     ;; return a proper stream, we are instead given a dummy stream.
+     ;; We can thus always store a stream and use
+     ;; `sys:pipe-exit-status` to obtain an exit status later.
+     ;; The advantage of dealing with streams instead of PID is the
+     ;; availability of functions like `sys:pipe-kill-process`.
+     (process :initform nil)
+     (input-stream :initform nil)
+     (output-stream :initform nil)
+     (bidir-stream :initform nil)
+     (error-output-stream :initform nil)
+     ;; For backward-compatibility, to maintain the property (zerop
+     ;; exit-code) <-> success, an exit in response to a signal is
+     ;; encoded as 128+signum.
+     (exit-code :initform nil)
+     ;; If the platform allows it, distinguish exiting with a code
+     ;; >128 from exiting in response to a signal by setting this code
+     (signal-code :initform nil)))
+
+;;;---------------------------------------------------------------------------
+;;; The following two helper functions take care of handling the IF-EXISTS and
+;;; IF-DOES-NOT-EXIST arguments for RUN-PROGRAM. In particular, they process the
+;;; :ERROR, :APPEND, and :SUPERSEDE arguments *here*, allowing the master
+;;; function to treat input and output files unconditionally for reading and
+;;; writing.
+;;;---------------------------------------------------------------------------
+
+  (defun %handle-if-exists (file if-exists)
+    (when (or (stringp file) (pathnamep file))
+      (ecase if-exists
+        ((:append :supersede :error)
+         (with-open-file (dummy file :direction :output :if-exists if-exists)
+           (declare (ignorable dummy)))))))
+
+  (defun %handle-if-does-not-exist (file if-does-not-exist)
+    (when (or (stringp file) (pathnamep file))
+      (ecase if-does-not-exist
+        ((:create :error)
+         (with-open-file (dummy file :direction :probe
+                                :if-does-not-exist if-does-not-exist)
+           (declare (ignorable dummy)))))))
+
+  (defun process-info-error-output (process-info)
+    (slot-value process-info 'error-output-stream))
+  (defun process-info-input (process-info)
+    (or (slot-value process-info 'bidir-stream)
+        (slot-value process-info 'input-stream)))
+  (defun process-info-output (process-info)
+    (or (slot-value process-info 'bidir-stream)
+        (slot-value process-info 'output-stream)))
+
+  (defun process-info-pid (process-info)
+    (let ((process (slot-value process-info 'process)))
+      (declare (ignorable process))
+      #+abcl (symbol-call :sys :process-pid process)
+      #+allegro process
+      #+clozure (ccl:external-process-id process)
+      #+ecl (ext:external-process-pid process)
+      #+(or cmucl scl) (ext:process-pid process)
+      #+lispworks7+ (sys:pipe-pid process)
+      #+(and lispworks (not lispworks7+)) process
+      #+mkcl (mkcl:process-id process)
+      #+sbcl (sb-ext:process-pid process)
+      #-(or abcl allegro clozure cmucl ecl mkcl lispworks sbcl scl)
+      (not-implemented-error 'process-info-pid)))
+
+  (defun %process-status (process-info)
+    (if-let (exit-code (slot-value process-info 'exit-code))
+      (return-from %process-status
+        (if-let (signal-code (slot-value process-info 'signal-code))
+          (values :signaled signal-code)
+          (values :exited exit-code))))
+    #-(or allegro clozure cmucl ecl lispworks mkcl sbcl scl)
+    (not-implemented-error '%process-status)
+    (if-let (process (slot-value process-info 'process))
+      (multiple-value-bind (status code)
+          (progn
+            #+allegro (multiple-value-bind (exit-code pid signal-code)
+                          (sys:reap-os-subprocess :pid process :wait nil)
+                        (assert pid)
+                        (%code-to-status exit-code signal-code))
+            #+clozure (ccl:external-process-status process)
+            #+(or cmucl scl) (let ((status (ext:process-status process)))
+                               (if (member status '(:exited :signaled))
+                                   ;; Calling ext:process-exit-code on
+                                   ;; processes that are still alive
+                                   ;; yields an undefined result
+                                   (values status (ext:process-exit-code process))
+                                   status))
+            #+ecl (ext:external-process-status process)
+            #+lispworks
+            ;; a signal is only returned on LispWorks 7+
+            (multiple-value-bind (exit-code signal-code)
+                (symbol-call :sys
+                             #+lispworks7+ :pipe-exit-status
+                             #-lispworks7+ :pid-exit-status
+                             process :wait nil)
+              (%code-to-status exit-code signal-code))
+            #+mkcl (let ((status (mk-ext:process-status process)))
+                     (if (eq status :exited)
+                         ;; Only call mk-ext:process-exit-code when
+                         ;; necessary since it leads to another waitpid()
+                         (let ((code (mk-ext:process-exit-code process)))
+                           (if (stringp code)
+                               (values :signaled (%mkcl-signal-to-number code))
+                               (values :exited code)))
+                         status))
+            #+sbcl (let ((status (sb-ext:process-status process)))
+                     (if (eq status :running)
+                         :running
+                         ;; sb-ext:process-exit-code can also be
+                         ;; called for stopped processes to determine
+                         ;; the signal that stopped them
+                         (values status (sb-ext:process-exit-code process)))))
+        (case status
+          (:exited (setf (slot-value process-info 'exit-code) code))
+          (:signaled (let ((%code (%signal-to-exit-code code)))
+                       (setf (slot-value process-info 'exit-code) %code
+                             (slot-value process-info 'signal-code) code))))
+        (if code
+            (values status code)
+            status))))
+
+  (defun process-alive-p (process-info)
+    "Check if a process has yet to exit."
+    (unless (slot-value process-info 'exit-code)
+      #+abcl (sys:process-alive-p (slot-value process-info 'process))
+      #+(or cmucl scl) (ext:process-alive-p (slot-value process-info 'process))
+      #+sbcl (sb-ext:process-alive-p (slot-value process-info 'process))
+      #-(or abcl cmucl sbcl scl) (find (%process-status process-info)
+                                       '(:running :stopped :continued :resumed))))
+
+  (defun wait-process (process-info)
+    "Wait for the process to terminate, if it is still running.
+Otherwise, return immediately. An exit code (a number) will be
+returned, with 0 indicating success, and anything else indicating
+failure. If the process exits after receiving a signal, the exit code
+will be the sum of 128 and the (positive) numeric signal code. A second
+value may be returned in this case: the numeric signal code itself.
+Any asynchronously spawned process requires this function to be run
+before it is garbage-collected in order to free up resources that
+might otherwise be irrevocably lost."
+    (if-let (exit-code (slot-value process-info 'exit-code))
+      (if-let (signal-code (slot-value process-info 'signal-code))
+        (values exit-code signal-code)
+        exit-code)
+      (let ((process (slot-value process-info 'process)))
+        #-(or abcl allegro clozure cmucl ecl lispworks mkcl sbcl scl)
+        (not-implemented-error 'wait-process)
+        (when process
+          ;; 1- wait
+          #+clozure (ccl::external-process-wait process)
+          #+(or cmucl scl) (ext:process-wait process)
+          #+sbcl (sb-ext:process-wait process)
+          ;; 2- extract result
+          (multiple-value-bind (exit-code signal-code)
+              (progn
+                #+abcl (sys:process-wait process)
+                #+allegro (multiple-value-bind (exit-code pid signal)
+                              (sys:reap-os-subprocess :pid process :wait t)
+                            (assert pid)
+                            (values exit-code signal))
+                #+clozure (multiple-value-bind (status code)
+                              (ccl:external-process-status process)
+                            (if (eq status :signaled)
+                                (values nil code)
+                                code))
+                #+(or cmucl scl) (let ((status (ext:process-status process))
+                                       (code (ext:process-exit-code process)))
+                                   (if (eq status :signaled)
+                                       (values nil code)
+                                       code))
+                #+ecl (multiple-value-bind (status code)
+                          (ext:external-process-wait process t)
+                        (if (eq status :signaled)
+                            (values nil code)
+                            code))
+                #+lispworks (symbol-call :sys
+                                         #+lispworks7+ :pipe-exit-status
+                                         #-lispworks7+ :pid-exit-status
+                                         process :wait t)
+                #+mkcl (let ((code (mkcl:join-process process)))
+                         (if (stringp code)
+                             (values nil (%mkcl-signal-to-number code))
+                             code))
+                #+sbcl (let ((status (sb-ext:process-status process))
+                             (code (sb-ext:process-exit-code process)))
+                         (if (eq status :signaled)
+                             (values nil code)
+                             code)))
+            (if signal-code
+                (let ((%exit-code (%signal-to-exit-code signal-code)))
+                  (setf (slot-value process-info 'exit-code) %exit-code
+                        (slot-value process-info 'signal-code) signal-code)
+                  (values %exit-code signal-code))
+                (progn (setf (slot-value process-info 'exit-code) exit-code)
+                       exit-code)))))))
+
+  ;; WARNING: For signals other than SIGTERM and SIGKILL this may not
+  ;; do what you expect it to. Sending SIGSTOP to a process spawned
+  ;; via LAUNCH-PROGRAM, e.g., will stop the shell /bin/sh that is used
+  ;; to run the command (via `sh -c command`) but not the actual
+  ;; command.
+  #+os-unix
+  (defun %posix-send-signal (process-info signal)
+    #+allegro (excl.osi:kill (slot-value process-info 'process) signal)
+    #+clozure (ccl:signal-external-process (slot-value process-info 'process)
+                                           signal :error-if-exited nil)
+    #+(or cmucl scl) (ext:process-kill (slot-value process-info 'process) signal)
+    #+sbcl (sb-ext:process-kill (slot-value process-info 'process) signal)
+    #-(or allegro clozure cmucl sbcl scl)
+    (if-let (pid (process-info-pid process-info))
+      (symbol-call :uiop :run-program
+                   (format nil "kill -~a ~a" signal pid) :ignore-error-status t)))
+
+  ;;; this function never gets called on Windows, but the compiler cannot tell
+  ;;; that. [2016/09/25:rpg]
+  #+os-windows
+  (defun %posix-send-signal (process-info signal)
+    (declare (ignore process-info signal))
+    (values))
+
+  (defun terminate-process (process-info &key urgent)
+    "Cause the process to exit. To that end, the process may or may
+not be sent a signal, which it will find harder (or even impossible)
+to ignore if URGENT is T. On some platforms, it may also be subject to
+race conditions."
+    (declare (ignorable urgent))
+    #+abcl (sys:process-kill (slot-value process-info 'process))
+    ;; On ECL, this will only work on versions later than 2016-09-06,
+    ;; but we still want to compile on earlier versions, so we use symbol-call
+    #+ecl (symbol-call :ext :terminate-process (slot-value process-info 'process) urgent)
+    #+lispworks7+ (sys:pipe-kill-process (slot-value process-info 'process))
+    #+mkcl (mk-ext:terminate-process (slot-value process-info 'process)
+                                     :force urgent)
+    #-(or abcl ecl lispworks7+ mkcl)
+    (os-cond
+     ((os-unix-p) (%posix-send-signal process-info (if urgent 9 15)))
+     ((os-windows-p) (if-let (pid (process-info-pid process-info))
+                       (symbol-call :uiop :run-program
+                                    (format nil "taskkill ~:[~;/f ~]/pid ~a" urgent pid)
+                                    :ignore-error-status t)))
+     (t (not-implemented-error 'terminate-process))))
+
+  (defun close-streams (process-info)
+    "Close any stream that the process might own. Needs to be run
+whenever streams were requested by passing :stream to :input, :output,
+or :error-output."
+    (dolist (stream
+              (cons (slot-value process-info 'error-output-stream)
+                    (if-let (bidir-stream (slot-value process-info 'bidir-stream))
+                      (list bidir-stream)
+                      (list (slot-value process-info 'input-stream)
+                            (slot-value process-info 'output-stream)))))
+      (when stream (close stream))))
+
+  (defun launch-program (command &rest keys
+                         &key
+                           input (if-input-does-not-exist :error)
+                           output (if-output-exists :supersede)
+                           error-output (if-error-output-exists :supersede)
+                           (element-type #-clozure *default-stream-element-type*
+                                         #+clozure 'character)
+                           (external-format *utf-8-external-format*)
+                           directory
+                           #+allegro separate-streams
+                           &allow-other-keys)
+    "Launch program specified by COMMAND,
+either a list of strings specifying a program and list of arguments,
+or a string specifying a shell command (/bin/sh on Unix, CMD.EXE on
+Windows) _asynchronously_.
+
+If OUTPUT is a pathname, a string designating a pathname, or NIL (the
+default) designating the null device, the file at that path is used as
+output.
+If it's :INTERACTIVE, output is inherited from the current process;
+beware that this may be different from your *STANDARD-OUTPUT*, and
+under SLIME will be on your *inferior-lisp* buffer.  If it's T, output
+goes to your current *STANDARD-OUTPUT* stream.  If it's :STREAM, a new
+stream will be made available that can be accessed via
+PROCESS-INFO-OUTPUT and read from. Otherwise, OUTPUT should be a value
+that the underlying lisp implementation knows how to handle.
+
+IF-OUTPUT-EXISTS, which is only meaningful if OUTPUT is a string or a
+pathname, can take the values :ERROR, :APPEND, and :SUPERSEDE (the
+default). The meaning of these values and their effect on the case
+where OUTPUT does not exist, is analogous to the IF-EXISTS parameter
+to OPEN with :DIRECTION :OUTPUT.
+
+ERROR-OUTPUT is similar to OUTPUT. T designates the *ERROR-OUTPUT*,
+:OUTPUT means redirecting the error output to the output stream,
+and :STREAM causes a stream to be made available via
+PROCESS-INFO-ERROR-OUTPUT.
+
+IF-ERROR-OUTPUT-EXISTS is similar to IF-OUTPUT-EXIST, except that it
+affects ERROR-OUTPUT rather than OUTPUT.
+
+INPUT is similar to OUTPUT, except that T designates the
+*STANDARD-INPUT* and a stream requested through the :STREAM keyword
+would be available through PROCESS-INFO-INPUT.
+
+IF-INPUT-DOES-NOT-EXIST, which is only meaningful if INPUT is a string
+or a pathname, can take the values :CREATE and :ERROR (the
+default). The meaning of these values is analogous to the
+IF-DOES-NOT-EXIST parameter to OPEN with :DIRECTION :INPUT.
+
+ELEMENT-TYPE and EXTERNAL-FORMAT are passed on to your Lisp
+implementation, when applicable, for creation of the output stream.
+
+LAUNCH-PROGRAM returns a PROCESS-INFO object.
+
+LAUNCH-PROGRAM currently does not smooth over all the differences between
+implementations. Of particular note is when streams are provided for OUTPUT or
+ERROR-OUTPUT. Some implementations don't support this at all, some support only
+certain subclasses of streams, and some support any arbitrary
+stream. Additionally, the implementations that support streams may have
+differing behavior on how those streams are filled with data. If data is not
+periodically read from the child process and sent to the stream, the child
+could block because its output buffers are full."
+    #-(or abcl allegro clozure cmucl ecl (and lispworks os-unix) mkcl sbcl scl)
+    (progn command keys input output error-output directory element-type external-format
+           if-input-does-not-exist if-output-exists if-error-output-exists ;; ignore
+           (not-implemented-error 'launch-program))
+    #+allegro
+    (when (some #'(lambda (stream)
+                    (and (streamp stream)
+                         (not (file-stream-p stream))))
+                (list input output error-output))
+      (parameter-error "~S: Streams passed as I/O parameters need to be file streams on this lisp"
+                       'launch-program))
+    #+(or abcl clisp lispworks)
+    (when (some #'streamp (list input output error-output))
+      (parameter-error "~S: I/O parameters cannot be foreign streams on this lisp"
+                       'launch-program))
+    #+clisp
+    (unless (eq error-output :interactive)
+      (parameter-error "~S: The only admissible value for ~S is ~S on this lisp"
+                       'launch-program :error-output :interactive))
+    #+ecl
+    (when (and (version< (lisp-implementation-version) "20.4.24")
+               (some #'(lambda (stream)
+                         (and (streamp stream)
+                              (not (file-or-synonym-stream-p stream))))
+                     (list input output error-output)))
+      (parameter-error "~S: Streams passed as I/O parameters need to be (synonymous with) file streams on this lisp"
+                       'launch-program))
+    #+(or abcl allegro clozure cmucl ecl (and lispworks os-unix) mkcl sbcl scl)
+    (nest
+     (progn ;; see comments for these functions
+       (%handle-if-does-not-exist input if-input-does-not-exist)
+       (%handle-if-exists output if-output-exists)
+       (%handle-if-exists error-output if-error-output-exists))
+     #+ecl (let ((*standard-input* *stdin*)
+                 (*standard-output* *stdout*)
+                 (*error-output* *stderr*)))
+     (let ((process-info (make-instance 'process-info))
+           (input (%normalize-io-specifier input :input))
+           (output (%normalize-io-specifier output :output))
+           (error-output (%normalize-io-specifier error-output :error-output))
+           #+(and allegro os-windows) (interactive (%interactivep input output error-output))
+           (command
+            (etypecase command
+              #+os-unix (string `("/bin/sh" "-c" ,command))
+              #+os-unix (list command)
+              #+os-windows
+              (string
+               ;; NB: On other Windows implementations, this is utterly bogus
+               ;; except in the most trivial cases where no quoting is needed.
+               ;; Use at your own risk.
+               #-(or allegro clisp clozure ecl)
+               (nest
+                #+(or ecl sbcl) (unless (find-symbol* :escape-arguments #+ecl :ext #+sbcl :sb-impl nil))
+                (parameter-error "~S doesn't support string commands on Windows on this Lisp"
+                                 'launch-program command))
+               ;; NB: We add cmd /c here. Behavior without going through cmd is not well specified
+               ;; when the command contains spaces or special characters:
+               ;; IIUC, the system will use space as a separator,
+               ;; but the C++ argv-decoding libraries won't, and
+               ;; you're supposed to use an extra argument to CreateProcess to bridge the gap,
+               ;; yet neither allegro nor clisp provide access to that argument.
+               #+(or allegro clisp) (strcat "cmd /c " command)
+               ;; On ClozureCL for Windows, we assume you are using
+               ;; r15398 or later in 1.9 or later,
+               ;; so that bug 858 is fixed http://trac.clozure.com/ccl/ticket/858
+               ;; On ECL, commit 2040629 https://gitlab.com/embeddable-common-lisp/ecl/issues/304
+               ;; On SBCL, we assume the patch from fcae0fd (to be part of SBCL 1.3.13)
+               #+(or clozure ecl sbcl) (cons "cmd" (strcat "/c " command)))
+              #+os-windows
+              (list
+               #+allegro (escape-windows-command command)
+               #-allegro command)))))
+     #+(or abcl (and allegro os-unix) clozure cmucl ecl mkcl sbcl)
+     (let ((program (car command))
+           #-allegro (arguments (cdr command))))
+     #+(and (or ecl sbcl) os-windows)
+     (multiple-value-bind (arguments escape-arguments)
+         (if (listp arguments)
+             (values arguments t)
+             (values (list arguments) nil)))
+     #-(or allegro mkcl sbcl) (with-current-directory (directory))
+     (multiple-value-bind
+       #+(or abcl clozure cmucl sbcl scl) (process)
+       #+allegro (in-or-io out-or-err err-or-pid pid-or-nil)
+       #+ecl (stream code process)
+       #+lispworks (io-or-pid err-or-nil #-lispworks7+ pid-or-nil)
+       #+mkcl (stream process code)
+       #.`(apply
+           #+abcl 'sys:run-program
+           #+allegro ,@'('excl:run-shell-command
+                         #+os-unix (coerce (cons program command) 'vector)
+                         #+os-windows command)
+           #+clozure 'ccl:run-program
+           #+(or cmucl ecl scl) 'ext:run-program
+           #+lispworks ,@'('system:run-shell-command `("/usr/bin/env" ,@command)) ; full path needed
+           #+mkcl 'mk-ext:run-program
+           #+sbcl 'sb-ext:run-program
+           #+(or abcl clozure cmucl ecl mkcl sbcl) ,@'(program arguments)
+           #+(and (or ecl sbcl) os-windows) ,@'(:escape-arguments escape-arguments)
+           :input input :if-input-does-not-exist :error
+           :output output :if-output-exists :append
+           ,(or #+(or allegro lispworks) :error-output :error) error-output
+           ,(or #+(or allegro lispworks) :if-error-output-exists :if-error-exists) :append
+           :wait nil :element-type element-type :external-format external-format
+           :allow-other-keys t
+           #+allegro ,@`(:directory directory
+                         #+os-windows ,@'(:show-window (if interactive nil :hide)))
+           #+lispworks ,@'(:save-exit-status t)
+           #+mkcl ,@'(:directory (native-namestring directory))
+           #-sbcl keys ;; on SBCL, don't pass :directory nil but remove it from the keys
+           #+sbcl ,@'(:search t (if directory keys (remove-plist-key :directory keys)))))
+     (labels ((prop (key value) (setf (slot-value process-info key) value)))
+       #+allegro
+       (cond
+         (separate-streams
+          (prop 'process pid-or-nil)
+          (when (eq input :stream) (prop 'input-stream in-or-io))
+          (when (eq output :stream) (prop 'output-stream out-or-err))
+          (when (eq error-output :stream) (prop 'error-output-stream err-or-pid)))
+         (t
+          (prop 'process err-or-pid)
+          (ecase (+ (if (eq input :stream) 1 0) (if (eq output :stream) 2 0))
+            (0)
+            (1 (prop 'input-stream in-or-io))
+            (2 (prop 'output-stream in-or-io))
+            (3 (prop 'bidir-stream in-or-io)))
+          (when (eq error-output :stream)
+            (prop 'error-output-stream out-or-err))))
+       #+(or abcl clozure cmucl sbcl scl)
+       (progn
+         (prop 'process process)
+         (when (eq input :stream)
+           (nest
+            (prop 'input-stream)
+            #+abcl (symbol-call :sys :process-input)
+            #+clozure (ccl:external-process-input-stream)
+            #+(or cmucl scl) (ext:process-input)
+            #+sbcl (sb-ext:process-input)
+            process))
+         (when (eq output :stream)
+           (nest
+            (prop 'output-stream)
+            #+abcl (symbol-call :sys :process-output)
+            #+clozure (ccl:external-process-output-stream)
+            #+(or cmucl scl) (ext:process-output)
+            #+sbcl (sb-ext:process-output)
+            process))
+         (when (eq error-output :stream)
+           (nest
+            (prop 'error-output-stream)
+            #+abcl (symbol-call :sys :process-error)
+            #+clozure (ccl:external-process-error-stream)
+            #+(or cmucl scl) (ext:process-error)
+            #+sbcl (sb-ext:process-error)
+            process)))
+       #+(or ecl mkcl)
+       (let ((mode (+ (if (eq input :stream) 1 0) (if (eq output :stream) 2 0))))
+         code ;; ignore
+         (unless (zerop mode)
+           (prop (case mode (1 'input-stream) (2 'output-stream) (3 'bidir-stream)) stream))
+         (when (eq error-output :stream)
+           (prop 'error-output-stream
+                 (if (version< (lisp-implementation-version) "16.0.0")
+                     (symbol-call :ext :external-process-error process)
+                     (symbol-call :ext :external-process-error-stream process))))
+         (prop 'process process))
+       #+lispworks
+       ;; See also the comments on the process-info class
+       (let ((mode (+ (if (eq input :stream) 1 0) (if (eq output :stream) 2 0))))
+         (cond
+           ((or (plusp mode) (eq error-output :stream))
+            (prop 'process #+lispworks7+ io-or-pid #-lispworks7+ pid-or-nil)
+            (when (plusp mode)
+              (prop (ecase mode (1 'input-stream) (2 'output-stream) (3 'bidir-stream))
+                    io-or-pid))
+            (when (eq error-output :stream)
+              (prop 'error-output-stream err-or-nil)))
+           ;; Prior to Lispworks 7, this returned (pid); now it
+           ;; returns (io err pid) of which we keep io.
+           (t (prop 'process io-or-pid)))))
+     process-info)))
+
+;;;; -------------------------------------------------------------------------
+;;;; run-program initially from xcvb-driver.
+
+(uiop/package:define-package :uiop/run-program
+  (:nicknames :asdf/run-program) ; OBSOLETE. Used by cl-sane, printv.
+  (:use :uiop/common-lisp :uiop/package :uiop/utility :uiop/version
+   :uiop/pathname :uiop/os :uiop/filesystem :uiop/stream :uiop/launch-program)
+  (:export
+   #:run-program
+   #:slurp-input-stream #:vomit-output-stream
+   #:subprocess-error
+   #:subprocess-error-code #:subprocess-error-command #:subprocess-error-process)
+  (:import-from :uiop/launch-program
+   #:%handle-if-does-not-exist #:%handle-if-exists #:%interactivep
+   #:input-stream #:output-stream #:error-output-stream))
+(in-package :uiop/run-program)
+
+;;;; Slurping a stream, typically the output of another program
+(with-upgradability ()
+  (defun call-stream-processor (fun processor stream)
+    "Given FUN (typically SLURP-INPUT-STREAM or VOMIT-OUTPUT-STREAM,
+a PROCESSOR specification which is either an atom or a list specifying
+a processor an keyword arguments, call the specified processor with
+the given STREAM as input"
+    (if (consp processor)
+        (apply fun (first processor) stream (rest processor))
+        (funcall fun processor stream)))
+
+  (defgeneric slurp-input-stream (processor input-stream &key)
+    (:documentation
+     "SLURP-INPUT-STREAM is a generic function with two positional arguments
+PROCESSOR and INPUT-STREAM and additional keyword arguments, that consumes (slurps)
+the contents of the INPUT-STREAM and processes them according to a method
+specified by PROCESSOR.
+
+Built-in methods include the following:
+* if PROCESSOR is a function, it is called with the INPUT-STREAM as its argument
+* if PROCESSOR is a list, its first element should be a function.  It will be applied to a cons of the
+  INPUT-STREAM and the rest of the list.  That is (x . y) will be treated as
+    \(APPLY x <stream> y\)
+* if PROCESSOR is an output-stream, the contents of INPUT-STREAM is copied to the output-stream,
+  per copy-stream-to-stream, with appropriate keyword arguments.
+* if PROCESSOR is the symbol CL:STRING or the keyword :STRING, then the contents of INPUT-STREAM
+  are returned as a string, as per SLURP-STREAM-STRING.
+* if PROCESSOR is the keyword :LINES then the INPUT-STREAM will be handled by SLURP-STREAM-LINES.
+* if PROCESSOR is the keyword :LINE then the INPUT-STREAM will be handled by SLURP-STREAM-LINE.
+* if PROCESSOR is the keyword :FORMS then the INPUT-STREAM will be handled by SLURP-STREAM-FORMS.
+* if PROCESSOR is the keyword :FORM then the INPUT-STREAM will be handled by SLURP-STREAM-FORM.
+* if PROCESSOR is T, it is treated the same as *standard-output*. If it is NIL, NIL is returned.
+
+Programmers are encouraged to define their own methods for this generic function."))
+
+  #-genera
+  (defmethod slurp-input-stream ((function function) input-stream &key)
+    (funcall function input-stream))
+
+  (defmethod slurp-input-stream ((list cons) input-stream &key)
+    (apply (first list) input-stream (rest list)))
+
+  #-genera
+  (defmethod slurp-input-stream ((output-stream stream) input-stream
+                                 &key linewise prefix (element-type 'character) buffer-size)
+    (copy-stream-to-stream
+     input-stream output-stream
+     :linewise linewise :prefix prefix :element-type element-type :buffer-size buffer-size))
+
+  (defmethod slurp-input-stream ((x (eql 'string)) stream &key stripped)
+    (slurp-stream-string stream :stripped stripped))
+
+  (defmethod slurp-input-stream ((x (eql :string)) stream &key stripped)
+    (slurp-stream-string stream :stripped stripped))
+
+  (defmethod slurp-input-stream ((x (eql :lines)) stream &key count)
+    (slurp-stream-lines stream :count count))
+
+  (defmethod slurp-input-stream ((x (eql :line)) stream &key (at 0))
+    (slurp-stream-line stream :at at))
+
+  (defmethod slurp-input-stream ((x (eql :forms)) stream &key count)
+    (slurp-stream-forms stream :count count))
+
+  (defmethod slurp-input-stream ((x (eql :form)) stream &key (at 0))
+    (slurp-stream-form stream :at at))
+
+  (defmethod slurp-input-stream ((x (eql t)) stream &rest keys &key &allow-other-keys)
+    (apply 'slurp-input-stream *standard-output* stream keys))
+
+  (defmethod slurp-input-stream ((x null) (stream t) &key)
+    nil)
+
+  (defmethod slurp-input-stream ((pathname pathname) input
+                                 &key
+                                   (element-type *default-stream-element-type*)
+                                   (external-format *utf-8-external-format*)
+                                   (if-exists :rename-and-delete)
+                                   (if-does-not-exist :create)
+                                   buffer-size
+                                   linewise)
+    (with-output-file (output pathname
+                              :element-type element-type
+                              :external-format external-format
+                              :if-exists if-exists
+                              :if-does-not-exist if-does-not-exist)
+      (copy-stream-to-stream
+       input output
+       :element-type element-type :buffer-size buffer-size :linewise linewise)))
+
+  (defmethod slurp-input-stream (x stream
+                                 &key linewise prefix (element-type 'character) buffer-size)
+    (declare (ignorable stream linewise prefix element-type buffer-size))
+    (cond
+      #+genera
+      ((functionp x) (funcall x stream))
+      #+genera
+      ((output-stream-p x)
+       (copy-stream-to-stream
+        stream x
+        :linewise linewise :prefix prefix :element-type element-type :buffer-size buffer-size))
+      (t
+       (parameter-error "Invalid ~S destination ~S" 'slurp-input-stream x)))))
+
+;;;; Vomiting a stream, typically into the input of another program.
+(with-upgradability ()
+  (defgeneric vomit-output-stream (processor output-stream &key)
+    (:documentation
+     "VOMIT-OUTPUT-STREAM is a generic function with two positional arguments
+PROCESSOR and OUTPUT-STREAM and additional keyword arguments, that produces (vomits)
+some content onto the OUTPUT-STREAM, according to a method specified by PROCESSOR.
+
+Built-in methods include the following:
+* if PROCESSOR is a function, it is called with the OUTPUT-STREAM as its argument
+* if PROCESSOR is a list, its first element should be a function.
+  It will be applied to a cons of the OUTPUT-STREAM and the rest of the list.
+  That is (x . y) will be treated as \(APPLY x <stream> y\)
+* if PROCESSOR is an input-stream, its contents will be copied the OUTPUT-STREAM,
+  per copy-stream-to-stream, with appropriate keyword arguments.
+* if PROCESSOR is a string, its contents will be printed to the OUTPUT-STREAM.
+* if PROCESSOR is T, it is treated the same as *standard-input*. If it is NIL, nothing is done.
+
+Programmers are encouraged to define their own methods for this generic function."))
+
+  #-genera
+  (defmethod vomit-output-stream ((function function) output-stream &key)
+    (funcall function output-stream))
+
+  (defmethod vomit-output-stream ((list cons) output-stream &key)
+    (apply (first list) output-stream (rest list)))
+
+  #-genera
+  (defmethod vomit-output-stream ((input-stream stream) output-stream
+                                 &key linewise prefix (element-type 'character) buffer-size)
+    (copy-stream-to-stream
+     input-stream output-stream
+     :linewise linewise :prefix prefix :element-type element-type :buffer-size buffer-size))
+
+  (defmethod vomit-output-stream ((x string) stream &key fresh-line terpri)
+    (princ x stream)
+    (when fresh-line (fresh-line stream))
+    (when terpri (terpri stream))
+    (values))
+
+  (defmethod vomit-output-stream ((x (eql t)) stream &rest keys &key &allow-other-keys)
+    (apply 'vomit-output-stream *standard-input* stream keys))
+
+  (defmethod vomit-output-stream ((x null) (stream t) &key)
+    (values))
+
+  (defmethod vomit-output-stream ((pathname pathname) input
+                                 &key
+                                   (element-type *default-stream-element-type*)
+                                   (external-format *utf-8-external-format*)
+                                   (if-exists :rename-and-delete)
+                                   (if-does-not-exist :create)
+                                   buffer-size
+                                   linewise)
+    (with-output-file (output pathname
+                              :element-type element-type
+                              :external-format external-format
+                              :if-exists if-exists
+                              :if-does-not-exist if-does-not-exist)
+      (copy-stream-to-stream
+       input output
+       :element-type element-type :buffer-size buffer-size :linewise linewise)))
+
+  (defmethod vomit-output-stream (x stream
+                                 &key linewise prefix (element-type 'character) buffer-size)
+    (declare (ignorable stream linewise prefix element-type buffer-size))
+    (cond
+      #+genera
+      ((functionp x) (funcall x stream))
+      #+genera
+      ((input-stream-p x)
+       (copy-stream-to-stream
+        x stream
+        :linewise linewise :prefix prefix :element-type element-type :buffer-size buffer-size))
+      (t
+       (parameter-error "Invalid ~S source ~S" 'vomit-output-stream x)))))
+
+
+;;;; Run-program: synchronously run a program in a subprocess, handling input, output and error-output.
+(with-upgradability ()
+  (define-condition subprocess-error (error)
+    ((code :initform nil :initarg :code :reader subprocess-error-code)
+     (command :initform nil :initarg :command :reader subprocess-error-command)
+     (process :initform nil :initarg :process :reader subprocess-error-process))
+    (:report (lambda (condition stream)
+               (format stream "Subprocess ~@[~S~% ~]~@[with command ~S~% ~]exited with error~@[ code ~D~]"
+                       (subprocess-error-process condition)
+                       (subprocess-error-command condition)
+                       (subprocess-error-code condition)))))
+
+  (defun %check-result (exit-code &key command process ignore-error-status)
+    (unless ignore-error-status
+      (unless (eql exit-code 0)
+        (cerror "IGNORE-ERROR-STATUS"
+                'subprocess-error :command command :code exit-code :process process)))
+    exit-code)
+
+  (defun %active-io-specifier-p (specifier)
+    "Determines whether a run-program I/O specifier requires Lisp-side processing
+via SLURP-INPUT-STREAM or VOMIT-OUTPUT-STREAM (return T),
+or whether it's already taken care of by the implementation's underlying run-program."
+    (not (typep specifier '(or null string pathname (member :interactive :output)
+                            #+(or cmucl (and sbcl os-unix) scl) (or stream (eql t))
+                            #+lispworks file-stream))))
+
+  (defun %run-program (command &rest keys &key &allow-other-keys)
+    "DEPRECATED. Use LAUNCH-PROGRAM instead."
+    (apply 'launch-program command keys))
+
+  (defun %call-with-program-io (gf tval stream-easy-p fun direction spec activep returner
+                                &key
+                                  (element-type #-clozure *default-stream-element-type* #+clozure 'character)
+                                  (external-format *utf-8-external-format*) &allow-other-keys)
+    ;; handle redirection for run-program and system
+    ;; SPEC is the specification for the subprocess's input or output or error-output
+    ;; TVAL is the value used if the spec is T
+    ;; GF is the generic function to call to handle arbitrary values of SPEC
+    ;; STREAM-EASY-P is T if we're going to use a RUN-PROGRAM that copies streams in the background
+    ;; (it's only meaningful on CMUCL, SBCL, SCL that actually do it)
+    ;; DIRECTION is :INPUT, :OUTPUT or :ERROR-OUTPUT for the direction of this io argument
+    ;; FUN is a function of the new reduced spec and an activity function to call with a stream
+    ;; when the subprocess is active and communicating through that stream.
+    ;; ACTIVEP is a boolean true if we will get to run code while the process is running
+    ;; ELEMENT-TYPE and EXTERNAL-FORMAT control what kind of temporary file we may open.
+    ;; RETURNER is a function called with the value of the activity.
+    ;; --- TODO (fare@tunes.org): handle if-output-exists and such when doing it the hard way.
+    (declare (ignorable stream-easy-p))
+    (let* ((actual-spec (if (eq spec t) tval spec))
+           (activity-spec (if (eq actual-spec :output)
+                              (ecase direction
+                                ((:input :output)
+                                 (parameter-error "~S does not allow ~S as a ~S spec"
+                                                  'run-program :output direction))
+                                ((:error-output)
+                                 nil))
+                              actual-spec)))
+      (labels ((activity (stream)
+                 (call-function returner (call-stream-processor gf activity-spec stream)))
+               (easy-case ()
+                 (funcall fun actual-spec nil))
+               (hard-case ()
+                 (if activep
+                     (funcall fun :stream #'activity)
+                     (with-temporary-file (:pathname tmp)
+                       (ecase direction
+                         (:input
+                          (with-output-file (s tmp :if-exists :overwrite
+                                               :external-format external-format
+                                               :element-type element-type)
+                            (activity s))
+                          (funcall fun tmp nil))
+                         ((:output :error-output)
+                          (multiple-value-prog1 (funcall fun tmp nil)
+                            (with-input-file (s tmp
+                                               :external-format external-format
+                                               :element-type element-type)
+                              (activity s)))))))))
+        (typecase activity-spec
+          ((or null string pathname (eql :interactive))
+           (easy-case))
+          #+(or cmucl (and sbcl os-unix) scl) ;; streams are only easy on implementations that try very hard
+          (stream
+           (if stream-easy-p (easy-case) (hard-case)))
+          (t
+           (hard-case))))))
+
+  (defmacro place-setter (place)
+    (when place
+      (let ((value (gensym)))
+        `#'(lambda (,value) (setf ,place ,value)))))
+
+  (defmacro with-program-input (((reduced-input-var
+                                  &optional (input-activity-var (gensym) iavp))
+                                 input-form &key setf stream-easy-p active keys) &body body)
+    `(apply '%call-with-program-io 'vomit-output-stream *standard-input* ,stream-easy-p
+            #'(lambda (,reduced-input-var ,input-activity-var)
+                ,@(unless iavp `((declare (ignore ,input-activity-var))))
+                ,@body)
+            :input ,input-form ,active (place-setter ,setf) ,keys))
+
+  (defmacro with-program-output (((reduced-output-var
+                                  &optional (output-activity-var (gensym) oavp))
+                                  output-form &key setf stream-easy-p active keys) &body body)
+    `(apply '%call-with-program-io 'slurp-input-stream *standard-output* ,stream-easy-p
+            #'(lambda (,reduced-output-var ,output-activity-var)
+                ,@(unless oavp `((declare (ignore ,output-activity-var))))
+                ,@body)
+            :output ,output-form ,active (place-setter ,setf) ,keys))
+
+  (defmacro with-program-error-output (((reduced-error-output-var
+                                         &optional (error-output-activity-var (gensym) eoavp))
+                                        error-output-form &key setf stream-easy-p active keys)
+                                       &body body)
+    `(apply '%call-with-program-io 'slurp-input-stream *error-output* ,stream-easy-p
+            #'(lambda (,reduced-error-output-var ,error-output-activity-var)
+                ,@(unless eoavp `((declare (ignore ,error-output-activity-var))))
+                ,@body)
+            :error-output ,error-output-form ,active (place-setter ,setf) ,keys))
+
+  (defun %use-launch-program (command &rest keys
+                           &key input output error-output ignore-error-status &allow-other-keys)
+    ;; helper for RUN-PROGRAM when using LAUNCH-PROGRAM
+    #+(or cormanlisp gcl (and lispworks os-windows) mcl xcl)
+    (progn
+      command keys input output error-output ignore-error-status ;; ignore
+      (not-implemented-error '%use-launch-program))
+    (when (member :stream (list input output error-output))
+      (parameter-error "~S: ~S is not allowed as synchronous I/O redirection argument"
+                       'run-program :stream))
+    (let* ((active-input-p (%active-io-specifier-p input))
+           (active-output-p (%active-io-specifier-p output))
+           (active-error-output-p (%active-io-specifier-p error-output))
+           (activity
+             (cond
+               (active-output-p :output)
+               (active-input-p :input)
+               (active-error-output-p :error-output)
+               (t nil)))
+           output-result error-output-result exit-code process-info)
+      (with-program-output ((reduced-output output-activity)
+                            output :keys keys :setf output-result
+                            :stream-easy-p t :active (eq activity :output))
+        (with-program-error-output ((reduced-error-output error-output-activity)
+                                    error-output :keys keys :setf error-output-result
+                                    :stream-easy-p t :active (eq activity :error-output))
+          (with-program-input ((reduced-input input-activity)
+                               input :keys keys
+                               :stream-easy-p t :active (eq activity :input))
+            (setf process-info
+                  (apply 'launch-program command
+                         :input reduced-input :output reduced-output
+                         :error-output (if (eq error-output :output) :output reduced-error-output)
+                         keys))
+            (labels ((get-stream (stream-name &optional fallbackp)
+                       (or (slot-value process-info stream-name)
+                           (when fallbackp
+                             (slot-value process-info 'bidir-stream))))
+                     (run-activity (activity stream-name &optional fallbackp)
+                       (if-let (stream (get-stream stream-name fallbackp))
+                         (funcall activity stream)
+                         (error 'subprocess-error
+                                :code `(:missing ,stream-name)
+                                :command command :process process-info))))
+              (unwind-protect
+                   (ecase activity
+                     ((nil))
+                     (:input (run-activity input-activity 'input-stream t))
+                     (:output (run-activity output-activity 'output-stream t))
+                     (:error-output (run-activity error-output-activity 'error-output-stream)))
+                (close-streams process-info)
+                (setf exit-code (wait-process process-info)))))))
+      (%check-result exit-code
+                     :command command :process process-info
+                     :ignore-error-status ignore-error-status)
+      (values output-result error-output-result exit-code)))
+
+  (defun %normalize-system-command (command) ;; helper for %USE-SYSTEM
+    (etypecase command
+      (string command)
+      (list (escape-shell-command
+             (os-cond
+              ((os-unix-p) (cons "exec" command))
+              (t command))))))
+
+  (defun %redirected-system-command (command in out err directory) ;; helper for %USE-SYSTEM
+    (flet ((redirect (spec operator)
+             (let ((pathname
+                     (typecase spec
+                       (null (null-device-pathname))
+                       (string (parse-native-namestring spec))
+                       (pathname spec)
+                       ((eql :output)
+                        (unless (equal operator " 2>>")
+                          (parameter-error "~S: only the ~S argument can be ~S"
+                                           'run-program :error-output :output))
+                        (return-from redirect '(" 2>&1"))))))
+               (when pathname
+                 (list operator " "
+                       (escape-shell-token (native-namestring pathname)))))))
+      (let* ((redirections (append (redirect in " <") (redirect out " >>") (redirect err " 2>>")))
+             (normalized (%normalize-system-command command))
+             (directory (or directory #+(or abcl xcl) (getcwd)))
+             (chdir (when directory
+                      (let ((dir-arg (escape-shell-token (native-namestring directory))))
+                        (os-cond
+                         ((os-unix-p) `("cd " ,dir-arg " ; "))
+                         ((os-windows-p) `("cd /d " ,dir-arg " & ")))))))
+        (reduce/strcat
+         (os-cond
+          ((os-unix-p) `(,@(when redirections `("exec " ,@redirections " ; ")) ,@chdir ,normalized))
+          ((os-windows-p) `(,@redirections " (" ,@chdir ,normalized ")")))))))
+
+  (defun %system (command &rest keys &key directory
+                                       input (if-input-does-not-exist :error)
+                                       output (if-output-exists :supersede)
+                                       error-output (if-error-output-exists :supersede)
+                                       &allow-other-keys)
+    "A portable abstraction of a low-level call to libc's system()."
+    (declare (ignorable keys directory input if-input-does-not-exist output
+                        if-output-exists error-output if-error-output-exists))
+    (when (member :stream (list input output error-output))
+      (parameter-error "~S: ~S is not allowed as synchronous I/O redirection argument"
+                       'run-program :stream))
+    #+(or abcl allegro clozure cmucl ecl (and lispworks os-unix) mkcl sbcl scl)
+    (let (#+(or abcl ecl mkcl)
+            (version (parse-version
+                      #-abcl
+                      (lisp-implementation-version)
+                      #+abcl
+                      (second (split-string (implementation-identifier) :separator '(#\-))))))
+      (nest
+       #+abcl (unless (lexicographic< '< version '(1 4 0)))
+       #+ecl (unless (lexicographic<= '< version '(16 0 0)))
+       #+mkcl (unless (lexicographic<= '< version '(1 1 9)))
+       (return-from %system
+         (wait-process
+          (apply 'launch-program (%normalize-system-command command) keys)))))
+    #+(or abcl clasp clisp cormanlisp ecl gcl genera (and lispworks os-windows) mkcl xcl)
+    (let ((%command (%redirected-system-command command input output error-output directory)))
+      ;; see comments for these functions
+      (%handle-if-does-not-exist input if-input-does-not-exist)
+      (%handle-if-exists output if-output-exists)
+      (%handle-if-exists error-output if-error-output-exists)
+      #+abcl (ext:run-shell-command %command)
+      #+(or clasp ecl) (let ((*standard-input* *stdin*)
+                             (*standard-output* *stdout*)
+                             (*error-output* *stderr*))
+                         (ext:system %command))
+      #+clisp
+      (let ((raw-exit-code
+             (or
+              #.`(#+os-windows ,@'(ext:run-shell-command %command)
+                  #+os-unix ,@'(ext:run-program "/bin/sh" :arguments `("-c" ,%command))
+                  :wait t :input :terminal :output :terminal)
+              0)))
+        (if (minusp raw-exit-code)
+            (- 128 raw-exit-code)
+            raw-exit-code))
+      #+cormanlisp (win32:system %command)
+      #+gcl (system:system %command)
+      #+genera (not-implemented-error '%system)
+      #+(and lispworks os-windows)
+      (system:call-system %command :current-directory directory :wait t)
+      #+mcl (ccl::with-cstrs ((%%command %command)) (_system %%command))
+      #+mkcl (mkcl:system %command)
+      #+xcl (system:%run-shell-command %command)))
+
+  (defun %use-system (command &rest keys
+                      &key input output error-output ignore-error-status &allow-other-keys)
+    ;; helper for RUN-PROGRAM when using %system
+    (let (output-result error-output-result exit-code)
+      (with-program-output ((reduced-output)
+                            output :keys keys :setf output-result)
+        (with-program-error-output ((reduced-error-output)
+                                    error-output :keys keys :setf error-output-result)
+          (with-program-input ((reduced-input) input :keys keys)
+            (setf exit-code (apply '%system command
+                                   :input reduced-input :output reduced-output
+                                   :error-output reduced-error-output keys)))))
+      (%check-result exit-code
+                     :command command
+                     :ignore-error-status ignore-error-status)
+      (values output-result error-output-result exit-code)))
+
+  (defun run-program (command &rest keys
+                       &key ignore-error-status (force-shell nil force-shell-suppliedp)
+                         input (if-input-does-not-exist :error)
+                         output (if-output-exists :supersede)
+                         error-output (if-error-output-exists :supersede)
+                         (element-type #-clozure *default-stream-element-type* #+clozure 'character)
+                         (external-format *utf-8-external-format*)
+                       &allow-other-keys)
+    "Run program specified by COMMAND,
+either a list of strings specifying a program and list of arguments,
+or a string specifying a shell command (/bin/sh on Unix, CMD.EXE on Windows);
+_synchronously_ process its output as specified and return the processing results
+when the program and its output processing are complete.
+
+Always call a shell (rather than directly execute the command when possible)
+if FORCE-SHELL is specified.  Similarly, never call a shell if FORCE-SHELL is
+specified to be NIL.
+
+Signal a continuable SUBPROCESS-ERROR if the process wasn't successful (exit-code 0),
+unless IGNORE-ERROR-STATUS is specified.
+
+If OUTPUT is a pathname, a string designating a pathname, or NIL (the default)
+designating the null device, the file at that path is used as output.
+If it's :INTERACTIVE, output is inherited from the current process;
+beware that this may be different from your *STANDARD-OUTPUT*,
+and under SLIME will be on your *inferior-lisp* buffer.
+If it's T, output goes to your current *STANDARD-OUTPUT* stream.
+Otherwise, OUTPUT should be a value that is a suitable first argument to
+SLURP-INPUT-STREAM (qv.), or a list of such a value and keyword arguments.
+In this case, RUN-PROGRAM will create a temporary stream for the program output;
+the program output, in that stream, will be processed by a call to SLURP-INPUT-STREAM,
+using OUTPUT as the first argument (or the first element of OUTPUT, and the rest as keywords).
+The primary value resulting from that call (or NIL if no call was needed)
+will be the first value returned by RUN-PROGRAM.
+E.g., using :OUTPUT :STRING will have it return the entire output stream as a string.
+And using :OUTPUT '(:STRING :STRIPPED T) will have it return the same string
+stripped of any ending newline.
+
+IF-OUTPUT-EXISTS, which is only meaningful if OUTPUT is a string or a
+pathname, can take the values :ERROR, :APPEND, and :SUPERSEDE (the
+default). The meaning of these values and their effect on the case
+where OUTPUT does not exist, is analogous to the IF-EXISTS parameter
+to OPEN with :DIRECTION :OUTPUT.
+
+ERROR-OUTPUT is similar to OUTPUT, except that the resulting value is returned
+as the second value of RUN-PROGRAM. T designates the *ERROR-OUTPUT*.
+Also :OUTPUT means redirecting the error output to the output stream,
+in which case NIL is returned.
+
+IF-ERROR-OUTPUT-EXISTS is similar to IF-OUTPUT-EXIST, except that it
+affects ERROR-OUTPUT rather than OUTPUT.
+
+INPUT is similar to OUTPUT, except that VOMIT-OUTPUT-STREAM is used,
+no value is returned, and T designates the *STANDARD-INPUT*.
+
+IF-INPUT-DOES-NOT-EXIST, which is only meaningful if INPUT is a string
+or a pathname, can take the values :CREATE and :ERROR (the
+default). The meaning of these values is analogous to the
+IF-DOES-NOT-EXIST parameter to OPEN with :DIRECTION :INPUT.
+
+ELEMENT-TYPE and EXTERNAL-FORMAT are passed on
+to your Lisp implementation, when applicable, for creation of the output stream.
+
+One and only one of the stream slurping or vomiting may or may not happen
+in parallel in parallel with the subprocess,
+depending on options and implementation,
+and with priority being given to output processing.
+Other streams are completely produced or consumed
+before or after the subprocess is spawned, using temporary files.
+
+RUN-PROGRAM returns 3 values:
+0- the result of the OUTPUT slurping if any, or NIL
+1- the result of the ERROR-OUTPUT slurping if any, or NIL
+2- either 0 if the subprocess exited with success status,
+or an indication of failure via the EXIT-CODE of the process"
+    (declare (ignorable input output error-output if-input-does-not-exist if-output-exists
+                        if-error-output-exists element-type external-format ignore-error-status))
+    #-(or abcl allegro clasp clisp clozure cmucl cormanlisp ecl gcl lispworks mcl mkcl sbcl scl xcl)
+    (not-implemented-error 'run-program)
+    (apply (if (or force-shell
+                   ;; Per doc string, set FORCE-SHELL to T if we get command as a string.
+                   ;; But don't override user's specified preference. [2015/06/29:rpg]
+                   (and (stringp command)
+                        (or (not force-shell-suppliedp)
+                            #-(or allegro clisp clozure sbcl) (os-cond ((os-windows-p) t))))
+                   #+(or clasp clisp cormanlisp gcl (and lispworks os-windows) mcl xcl) t
+                   ;; A race condition in ECL <= 16.0.0 prevents using ext:run-program
+                   #+ecl #.(if-let (ver (parse-version (lisp-implementation-version)))
+                                   (lexicographic<= '< ver '(16 0 0)))
+                   #+(and lispworks os-unix) (%interactivep input output error-output))
+               '%use-system '%use-launch-program)
+           command keys)))
+
+;;;; ---------------------------------------------------------------------------
+;;;; Generic support for configuration files
+
+(uiop/package:define-package :uiop/configuration
+  (:recycle :uiop/configuration :asdf/configuration) ;; necessary to upgrade from 2.27.
+  (:use :uiop/package :uiop/common-lisp :uiop/utility
+   :uiop/os :uiop/pathname :uiop/filesystem :uiop/stream :uiop/image :uiop/lisp-build)
+  (:export
+   #:user-configuration-directories #:system-configuration-directories ;; implemented in backward-driver
+   #:in-first-directory #:in-user-configuration-directory #:in-system-configuration-directory ;; idem
+   #:get-folder-path
+   #:xdg-data-home #:xdg-config-home #:xdg-data-dirs #:xdg-config-dirs
+   #:xdg-cache-home #:xdg-runtime-dir #:system-config-pathnames
+   #:filter-pathname-set #:xdg-data-pathnames #:xdg-config-pathnames
+   #:find-preferred-file #:xdg-data-pathname #:xdg-config-pathname
+   #:validate-configuration-form #:validate-configuration-file #:validate-configuration-directory
+   #:configuration-inheritance-directive-p
+   #:report-invalid-form #:invalid-configuration #:*ignored-configuration-form* #:*user-cache*
+   #:*clear-configuration-hook* #:clear-configuration #:register-clear-configuration-hook
+   #:resolve-location #:location-designator-p #:location-function-p #:*here-directory*
+   #:resolve-relative-location #:resolve-absolute-location #:upgrade-configuration
+   #:uiop-directory))
+(in-package :uiop/configuration)
+
+(with-upgradability ()
+  (define-condition invalid-configuration ()
+    ((form :reader condition-form :initarg :form)
+     (location :reader condition-location :initarg :location)
+     (format :reader condition-format :initarg :format)
+     (arguments :reader condition-arguments :initarg :arguments :initform nil))
+    (:report (lambda (c s)
+               (format s (compatfmt "~@<~? (will be skipped)~@:>")
+                       (condition-format c)
+                       (list* (condition-form c) (condition-location c)
+                              (condition-arguments c))))))
+
+  (defun configuration-inheritance-directive-p (x)
+    "Is X a configuration inheritance directive?"
+    (let ((kw '(:inherit-configuration :ignore-inherited-configuration)))
+      (or (member x kw)
+          (and (length=n-p x 1) (member (car x) kw)))))
+
+  (defun report-invalid-form (reporter &rest args)
+    "Report an invalid form according to REPORTER and various ARGS"
+    (etypecase reporter
+      (null
+       (apply 'error 'invalid-configuration args))
+      (function
+       (apply reporter args))
+      ((or symbol string)
+       (apply 'error reporter args))
+      (cons
+       (apply 'apply (append reporter args)))))
+
+  (defvar *ignored-configuration-form* nil
+    "Have configuration forms been ignored while parsing the configuration?")
+
+  (defun validate-configuration-form (form tag directive-validator
+                                            &key location invalid-form-reporter)
+    "Validate a configuration FORM. By default it will raise an error if the
+FORM is not valid.  Otherwise it will return the validated form.
+     Arguments control the behavior:
+     The configuration FORM should be of the form (TAG . <rest>)
+     Each element of <rest> will be checked by first seeing if it's a configuration inheritance
+directive (see CONFIGURATION-INHERITANCE-DIRECTIVE-P) then invoking DIRECTIVE-VALIDATOR
+on it.
+     In the event of an invalid form, INVALID-FORM-REPORTER will be used to control
+reporting (see REPORT-INVALID-FORM) with LOCATION providing information about where
+the configuration form appeared."
+    (unless (and (consp form) (eq (car form) tag))
+      (setf *ignored-configuration-form* t)
+      (report-invalid-form invalid-form-reporter :form form :location location)
+      (return-from validate-configuration-form nil))
+    (loop :with inherit = 0 :with ignore-invalid-p = nil :with x = (list tag)
+          :for directive :in (cdr form)
+          :when (cond
+                  ((configuration-inheritance-directive-p directive)
+                   (incf inherit) t)
+                  ((eq directive :ignore-invalid-entries)
+                   (setf ignore-invalid-p t) t)
+                  ((funcall directive-validator directive)
+                   t)
+                  (ignore-invalid-p
+                   nil)
+                  (t
+                   (setf *ignored-configuration-form* t)
+                   (report-invalid-form invalid-form-reporter :form directive :location location)
+                   nil))
+            :do (push directive x)
+          :finally
+             (unless (= inherit 1)
+               (report-invalid-form invalid-form-reporter
+                                    :form form :location location
+                                    ;; we throw away the form and location arguments, hence the ~2*
+                                    ;; this is necessary because of the report in INVALID-CONFIGURATION
+                                    :format (compatfmt "~@<Invalid source registry ~S~@[ in ~S~]. ~
+                                                        One and only one of ~S or ~S is required.~@:>")
+                                    :arguments '(:inherit-configuration :ignore-inherited-configuration)))
+             (return (nreverse x))))
+
+  (defun validate-configuration-file (file validator &key description)
+    "Validate a configuration FILE.  The configuration file should have only one s-expression
+in it, which will be checked with the VALIDATOR FORM.  DESCRIPTION argument used for error
+reporting."
+    (let ((forms (read-file-forms file)))
+      (unless (length=n-p forms 1)
+        (error (compatfmt "~@<One and only one form allowed for ~A. Got: ~3i~_~S~@:>~%")
+               description forms))
+      (funcall validator (car forms) :location file)))
+
+  (defun validate-configuration-directory (directory tag validator &key invalid-form-reporter)
+    "Map the VALIDATOR across the .conf files in DIRECTORY, the TAG will
+be applied to the results to yield a configuration form.  Current
+values of TAG include :source-registry and :output-translations."
+    (let ((files (sort (ignore-errors ;; SORT w/o COPY-LIST is OK: DIRECTORY returns a fresh list
+                        (remove-if
+                         'hidden-pathname-p
+                         (directory* (make-pathname :name *wild* :type "conf" :defaults directory))))
+                       #'string< :key #'namestring)))
+      `(,tag
+        ,@(loop :for file :in files :append
+                                    (loop :with ignore-invalid-p = nil
+                                          :for form :in (read-file-forms file)
+                                          :when (eq form :ignore-invalid-entries)
+                                            :do (setf ignore-invalid-p t)
+                                          :else
+                                            :when (funcall validator form)
+                                              :collect form
+                                          :else
+                                            :when ignore-invalid-p
+                                              :do (setf *ignored-configuration-form* t)
+                                          :else
+                                            :do (report-invalid-form invalid-form-reporter :form form :location file)))
+        :inherit-configuration)))
+
+  (defun resolve-relative-location (x &key ensure-directory wilden)
+    "Given a designator X for an relative location, resolve it to a pathname."
+    (ensure-pathname
+     (etypecase x
+       (null nil)
+       (pathname x)
+       (string (parse-unix-namestring
+                x :ensure-directory ensure-directory))
+       (cons
+        (if (null (cdr x))
+            (resolve-relative-location
+             (car x) :ensure-directory ensure-directory :wilden wilden)
+            (let* ((car (resolve-relative-location
+                         (car x) :ensure-directory t :wilden nil)))
+              (merge-pathnames*
+               (resolve-relative-location
+                (cdr x) :ensure-directory ensure-directory :wilden wilden)
+               car))))
+       ((eql :*/) *wild-directory*)
+       ((eql :**/) *wild-inferiors*)
+       ((eql :*.*.*) *wild-file*)
+       ((eql :implementation)
+        (parse-unix-namestring
+         (implementation-identifier) :ensure-directory t))
+       ((eql :implementation-type)
+        (parse-unix-namestring
+         (string-downcase (implementation-type)) :ensure-directory t))
+       ((eql :hostname)
+        (parse-unix-namestring (hostname) :ensure-directory t)))
+     :wilden (and wilden (not (pathnamep x)) (not (member x '(:*/ :**/ :*.*.*))))
+     :want-relative t))
+
+  (defvar *here-directory* nil
+    "This special variable is bound to the currect directory during calls to
+PROCESS-SOURCE-REGISTRY in order that we be able to interpret the :here
+directive.")
+
+  (defvar *user-cache* nil
+    "A specification as per RESOLVE-LOCATION of where the user keeps his FASL cache")
+
+  (defun resolve-absolute-location (x &key ensure-directory wilden)
+    "Given a designator X for an absolute location, resolve it to a pathname"
+    (ensure-pathname
+     (etypecase x
+       (null nil)
+       (pathname x)
+       (string
+        (let ((p #-mcl (parse-namestring x)
+                 #+mcl (probe-posix x)))
+          #+mcl (unless p (error "POSIX pathname ~S does not exist" x))
+          (if ensure-directory (ensure-directory-pathname p) p)))
+       (cons
+        (return-from resolve-absolute-location
+          (if (null (cdr x))
+              (resolve-absolute-location
+               (car x) :ensure-directory ensure-directory :wilden wilden)
+              (merge-pathnames*
+               (resolve-relative-location
+                (cdr x) :ensure-directory ensure-directory :wilden wilden)
+               (resolve-absolute-location
+                (car x) :ensure-directory t :wilden nil)))))
+       ((eql :root)
+        ;; special magic! we return a relative pathname,
+        ;; but what it means to the output-translations is
+        ;; "relative to the root of the source pathname's host and device".
+        (return-from resolve-absolute-location
+          (let ((p (make-pathname :directory '(:relative))))
+            (if wilden (wilden p) p))))
+       ((eql :home) (user-homedir-pathname))
+       ((eql :here) (resolve-absolute-location
+                     (or *here-directory* (pathname-directory-pathname (truename (load-pathname))))
+                     :ensure-directory t :wilden nil))
+       ((eql :user-cache) (resolve-absolute-location
+                           *user-cache* :ensure-directory t :wilden nil)))
+     :wilden (and wilden (not (pathnamep x)))
+     :resolve-symlinks *resolve-symlinks*
+     :want-absolute t))
+
+  ;; Try to override declaration in previous versions of ASDF.
+  (declaim (ftype (function (t &key (:directory boolean) (:wilden boolean)
+                               (:ensure-directory boolean)) t) resolve-location))
+
+  (defun resolve-location (x &key ensure-directory wilden directory)
+    "Resolve location designator X into a PATHNAME"
+    ;; :directory backward compatibility, until 2014-01-16: accept directory as well as ensure-directory
+    (loop :with dirp = (or directory ensure-directory)
+          :with (first . rest) = (if (atom x) (list x) x)
+          :with path = (or (resolve-absolute-location
+                            first :ensure-directory (and (or dirp rest) t)
+                            :wilden (and wilden (null rest)))
+                           (return nil))
+          :for (element . morep) :on rest
+          :for dir = (and (or morep dirp) t)
+          :for wild = (and wilden (not morep))
+          :for sub = (merge-pathnames*
+                      (resolve-relative-location
+                       element :ensure-directory dir :wilden wild)
+                      path)
+          :do (setf path (if (absolute-pathname-p sub) (resolve-symlinks* sub) sub))
+          :finally (return path)))
+
+  (defun location-designator-p (x)
+    "Is X a designator for a location?"
+    ;; NIL means "skip this entry", or as an output translation, same as translation input.
+    ;; T means "any input" for a translation, or as output, same as translation input.
+    (flet ((absolute-component-p (c)
+             (typep c '(or string pathname
+                        (member :root :home :here :user-cache))))
+           (relative-component-p (c)
+             (typep c '(or string pathname
+                        (member :*/ :**/ :*.*.* :implementation :implementation-type)))))
+      (or (typep x 'boolean)
+          (absolute-component-p x)
+          (and (consp x) (absolute-component-p (first x)) (every #'relative-component-p (rest x))))))
+
+  (defun location-function-p (x)
+    "Is X the specification of a location function?"
+    ;; Location functions are allowed in output translations, and notably used by ABCL for JAR file support.
+    (and (length=n-p x 2) (eq (car x) :function)))
+
+  (defvar *clear-configuration-hook* '())
+
+  (defun register-clear-configuration-hook (hook-function &optional call-now-p)
+    "Register a function to be called when clearing configuration"
+    (register-hook-function '*clear-configuration-hook* hook-function call-now-p))
+
+  (defun clear-configuration ()
+    "Call the functions in *CLEAR-CONFIGURATION-HOOK*"
+    (call-functions *clear-configuration-hook*))
+
+  (register-image-dump-hook 'clear-configuration)
+
+  (defun upgrade-configuration ()
+    "If a previous version of ASDF failed to read some configuration, try again now."
+    (when *ignored-configuration-form*
+      (clear-configuration)
+      (setf *ignored-configuration-form* nil)))
+
+
+  (defun get-folder-path (folder)
+    "Semi-portable implementation of a subset of LispWorks' sys:get-folder-path,
+this function tries to locate the Windows FOLDER for one of
+:LOCAL-APPDATA, :APPDATA or :COMMON-APPDATA.
+     Returns NIL when the folder is not defined (e.g., not on Windows)."
+    (or #+(and lispworks os-windows) (sys:get-folder-path folder)
+        ;; read-windows-registry HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders\AppData
+        (ecase folder
+          (:local-appdata (or (getenv-absolute-directory "LOCALAPPDATA")
+                              (subpathname* (get-folder-path :appdata) "Local")))
+          (:appdata (getenv-absolute-directory "APPDATA"))
+          (:common-appdata (or (getenv-absolute-directory "ALLUSERSAPPDATA")
+                               (subpathname* (getenv-absolute-directory "ALLUSERSPROFILE") "Application Data/"))))))
+
+
+  ;; Support for the XDG Base Directory Specification
+  (defun xdg-data-home (&rest more)
+    "Returns an absolute pathname for the directory containing user-specific data files.
+MORE may contain specifications for a subpath relative to this directory: a
+subpathname specification and keyword arguments as per RESOLVE-LOCATION \(see
+also \"Configuration DSL\"\) in the ASDF manual."
+    (resolve-absolute-location
+     `(,(or (getenv-absolute-directory "XDG_DATA_HOME")
+            (os-cond
+             ((os-windows-p) (get-folder-path :local-appdata))
+             (t (subpathname (user-homedir-pathname) ".local/share/"))))
+       ,more)))
+
+  (defun xdg-config-home (&rest more)
+    "Returns a pathname for the directory containing user-specific configuration files.
+MORE may contain specifications for a subpath relative to this directory: a
+subpathname specification and keyword arguments as per RESOLVE-LOCATION \(see
+also \"Configuration DSL\"\) in the ASDF manual."
+    (resolve-absolute-location
+     `(,(or (getenv-absolute-directory "XDG_CONFIG_HOME")
+            (os-cond
+             ((os-windows-p) (xdg-data-home "config/"))
+             (t (subpathname (user-homedir-pathname) ".config/"))))
+       ,more)))
+
+  (defun xdg-data-dirs (&rest more)
+    "The preference-ordered set of additional paths to search for data files.
+Returns a list of absolute directory pathnames.
+MORE may contain specifications for a subpath relative to these directories: a
+subpathname specification and keyword arguments as per RESOLVE-LOCATION \(see
+also \"Configuration DSL\"\) in the ASDF manual."
+    (mapcar #'(lambda (d) (resolve-location `(,d ,more)))
+            (or (remove nil (getenv-absolute-directories "XDG_DATA_DIRS"))
+                (os-cond
+                 ((os-windows-p) (mapcar 'get-folder-path '(:appdata :common-appdata)))
+                 ;; macOS' separate read-only system volume means that the contents
+                 ;; of /usr/share are frozen by Apple. Unlike when running natively
+                 ;; on macOS, Genera must access the filesystem through NFS. Attempting
+                 ;; to export either the root (/) or /usr/share simply doesn't work.
+                 ;; (Genera will go into an infinite loop trying to access those mounts.)
+                 ;; So, when running Genera on macOS, only search /usr/local/share.
+                 ((os-genera-p)
+                  #+Genera (sys:system-case
+                            (darwin-vlm (mapcar 'parse-unix-namestring '("/usr/local/share/")))
+                            (otherwise (mapcar 'parse-unix-namestring '("/usr/local/share/" "/usr/share/")))))
+                 (t (mapcar 'parse-unix-namestring '("/usr/local/share/" "/usr/share/")))))))
+
+  (defun xdg-config-dirs (&rest more)
+    "The preference-ordered set of additional base paths to search for configuration files.
+Returns a list of absolute directory pathnames.
+MORE may contain specifications for a subpath relative to these directories:
+subpathname specification and keyword arguments as per RESOLVE-LOCATION \(see
+also \"Configuration DSL\"\) in the ASDF manual."
+    (mapcar #'(lambda (d) (resolve-location `(,d ,more)))
+            (or (remove nil (getenv-absolute-directories "XDG_CONFIG_DIRS"))
+                (os-cond
+                 ((os-windows-p) (xdg-data-dirs "config/"))
+                 (t (mapcar 'parse-unix-namestring '("/etc/xdg/")))))))
+
+  (defun xdg-cache-home (&rest more)
+    "The base directory relative to which user specific non-essential data files should be stored.
+Returns an absolute directory pathname.
+MORE may contain specifications for a subpath relative to this directory: a
+subpathname specification and keyword arguments as per RESOLVE-LOCATION \(see
+also \"Configuration DSL\"\) in the ASDF manual."
+    (resolve-absolute-location
+     `(,(or (getenv-absolute-directory "XDG_CACHE_HOME")
+            (os-cond
+             ((os-windows-p) (xdg-data-home "cache/"))
+             (t (subpathname* (user-homedir-pathname) ".cache/"))))
+       ,more)))
+
+  (defun xdg-runtime-dir (&rest more)
+    "Pathname for user-specific non-essential runtime files and other file objects,
+such as sockets, named pipes, etc.
+Returns an absolute directory pathname.
+MORE may contain specifications for a subpath relative to this directory: a
+subpathname specification and keyword arguments as per RESOLVE-LOCATION \(see
+also \"Configuration DSL\"\) in the ASDF manual."
+    ;; The XDG spec says that if not provided by the login system, the application should
+    ;; issue a warning and provide a replacement. UIOP is not equipped to do that and returns NIL.
+    (resolve-absolute-location `(,(getenv-absolute-directory "XDG_RUNTIME_DIR") ,more)))
+
+  ;;; NOTE: modified the docstring because "system user configuration
+  ;;; directories" seems self-contradictory. I'm not sure my wording is right.
+  (defun system-config-pathnames (&rest more)
+    "Return a list of directories where are stored the system's default user configuration information.
+MORE may contain specifications for a subpath relative to these directories: a
+subpathname specification and keyword arguments as per RESOLVE-LOCATION \(see
+also \"Configuration DSL\"\) in the ASDF manual."
+    (declare (ignorable more))
+    (os-cond
+     ((os-unix-p) (list (resolve-absolute-location `(,(parse-unix-namestring "/etc/") ,more))))))
+
+  (defun filter-pathname-set (dirs)
+    "Parse strings as unix namestrings and remove duplicates and non absolute-pathnames in a list."
+    (remove-duplicates (remove-if-not #'absolute-pathname-p dirs) :from-end t :test 'equal))
+
+  (defun xdg-data-pathnames (&rest more)
+    "Return a list of absolute pathnames for application data directories.  With APP,
+returns directory for data for that application, without APP, returns the set of directories
+for storing all application configurations.
+MORE may contain specifications for a subpath relative to these directories: a
+subpathname specification and keyword arguments as per RESOLVE-LOCATION \(see
+also \"Configuration DSL\"\) in the ASDF manual."
+    (filter-pathname-set
+     `(,(xdg-data-home more)
+       ,@(xdg-data-dirs more))))
+
+  (defun xdg-config-pathnames (&rest more)
+    "Return a list of pathnames for application configuration.
+MORE may contain specifications for a subpath relative to these directories: a
+subpathname specification and keyword arguments as per RESOLVE-LOCATION \(see
+also \"Configuration DSL\"\) in the ASDF manual."
+    (filter-pathname-set
+     `(,(xdg-config-home more)
+       ,@(xdg-config-dirs more))))
+
+  (defun find-preferred-file (files &key (direction :input))
+    "Find first file in the list of FILES that exists (for direction :input or :probe)
+or just the first one (for direction :output or :io).
+    Note that when we say \"file\" here, the files in question may be directories."
+    (find-if (ecase direction ((:probe :input) 'probe-file*) ((:output :io) 'identity)) files))
+
+  (defun xdg-data-pathname (&optional more (direction :input))
+    (find-preferred-file (xdg-data-pathnames more) :direction direction))
+
+  (defun xdg-config-pathname (&optional more (direction :input))
+    (find-preferred-file (xdg-config-pathnames more) :direction direction))
+
+  (defun compute-user-cache ()
+    "Compute (and return) the location of the default user-cache for translate-output
+objects. Side-effects for cached file location computation."
+    (setf *user-cache* (xdg-cache-home "common-lisp" :implementation)))
+  (register-image-restore-hook 'compute-user-cache)
+
+  (defun uiop-directory ()
+    "Try to locate the UIOP source directory at runtime"
+    (labels ((pf (x) (ignore-errors (probe-file* x)))
+             (sub (x y) (pf (subpathname x y)))
+             (ssd (x) (ignore-errors (symbol-call :asdf :system-source-directory x))))
+      ;; NB: conspicuously *not* including searches based on #.(current-lisp-pathname)
+      (or
+       ;; Look under uiop if available as source override, under asdf if avaiable as source
+       (ssd "uiop")
+       (sub (ssd "asdf") "uiop/")
+       ;; Look in recommended path for user-visible source installation
+       (sub (user-homedir-pathname) "common-lisp/asdf/uiop/")
+       ;; Look in XDG paths under known package names for user-invisible source installation
+       (xdg-data-pathname "common-lisp/source/asdf/uiop/")
+       (xdg-data-pathname "common-lisp/source/cl-asdf/uiop/") ; traditional Debian location
+       ;; The last one below is useful for Fare, primary (sole?) known user
+       (sub (user-homedir-pathname) "cl/asdf/uiop/")
+       (cerror "Configure source registry to include UIOP source directory and retry."
+               "Unable to find UIOP directory")
+       (uiop-directory)))))
+;;; -------------------------------------------------------------------------
+;;; Hacks for backward-compatibility with older versions of UIOP
+
+(uiop/package:define-package :uiop/backward-driver
+  (:recycle :uiop/backward-driver :asdf/backward-driver :uiop)
+  (:use :uiop/common-lisp :uiop/package :uiop/utility :uiop/version
+   :uiop/pathname :uiop/stream :uiop/os :uiop/image
+   :uiop/run-program :uiop/lisp-build :uiop/configuration)
+  (:export
+   #:coerce-pathname
+   #:user-configuration-directories #:system-configuration-directories
+   #:in-first-directory #:in-user-configuration-directory #:in-system-configuration-directory
+   #:version-compatible-p))
+(in-package :uiop/backward-driver)
+
+(eval-when (:compile-toplevel :load-toplevel :execute)
+(with-deprecation ((version-deprecation *uiop-version* :style-warning "3.2" :warning "3.4"))
+  ;; Backward compatibility with ASDF 2.000 to 2.26
+
+  ;; For backward-compatibility only, for people using internals
+  ;; Reported users in quicklisp 2015-11: hu.dwim.asdf (removed in next release)
+  ;; Will be removed after 2015-12.
+  (defun coerce-pathname (name &key type defaults)
+    "DEPRECATED. Please use UIOP:PARSE-UNIX-NAMESTRING instead."
+    (parse-unix-namestring name :type type :defaults defaults))
+
+  ;; Backward compatibility for ASDF 2.27 to 3.1.4
+  (defun user-configuration-directories ()
+    "Return the current user's list of user configuration directories
+for configuring common-lisp.
+DEPRECATED. Use UIOP:XDG-CONFIG-PATHNAMES instead."
+    (xdg-config-pathnames "common-lisp"))
+  (defun system-configuration-directories ()
+    "Return the list of system configuration directories for common-lisp.
+DEPRECATED. Use UIOP:SYSTEM-CONFIG-PATHNAMES (with argument \"common-lisp\"),
+instead."
+    (system-config-pathnames "common-lisp"))
+  (defun in-first-directory (dirs x &key (direction :input))
+    "Finds the first appropriate file named X in the list of DIRS for I/O
+in DIRECTION \(which may be :INPUT, :OUTPUT, :IO, or :PROBE).
+If direction is :INPUT or :PROBE, will return the first extant file named
+X in one of the DIRS.
+If direction is :OUTPUT or :IO, will simply return the file named X in the
+first element of DIRS that exists. DEPRECATED."
+    (find-preferred-file
+     (mapcar #'(lambda (dir) (subpathname (ensure-directory-pathname dir) x)) dirs)
+     :direction direction))
+  (defun in-user-configuration-directory (x &key (direction :input))
+    "Return the file named X in the user configuration directory for common-lisp.
+DEPRECATED."
+    (xdg-config-pathname `("common-lisp" ,x) direction))
+  (defun in-system-configuration-directory (x &key (direction :input))
+    "Return the pathname for the file named X under the system configuration directory
+for common-lisp. DEPRECATED."
+    (find-preferred-file (system-config-pathnames "common-lisp" x) :direction direction))
+
+
+  ;; Backward compatibility with ASDF 1 to ASDF 2.32
+
+  (defun version-compatible-p (provided-version required-version)
+    "Is the provided version a compatible substitution for the required-version?
+If major versions differ, it's not compatible.
+If they are equal, then any later version is compatible,
+with later being determined by a lexicographical comparison of minor numbers.
+DEPRECATED."
+    (let ((x (parse-version provided-version nil))
+          (y (parse-version required-version nil)))
+      (and x y (= (car x) (car y)) (lexicographic<= '< (cdr y) (cdr x)))))))
+
+;;;; ---------------------------------------------------------------------------
+;;;; Re-export all the functionality in UIOP
+
+(uiop/package:define-package :uiop/driver
+  (:nicknames :uiop ;; Official name we recommend should be used for all references to uiop symbols.
+              :asdf/driver) ;; DO NOT USE, a deprecated name, not supported anymore.
+  ;; We should remove the name :asdf/driver at some point,
+  ;; but not until it has been eradicated from Quicklisp for a year or two.
+  ;; The last known user was cffi (PR merged in May 2020).
+  (:use :uiop/common-lisp)
+  ;; NB: We are not reexporting uiop/common-lisp
+  ;; which include all of CL with compatibility modifications on select platforms,
+  ;; because that would cause potential conflicts for packages that
+  ;; might want to :use (:cl :uiop) or :use (:closer-common-lisp :uiop), etc.
+  (:use-reexport
+   :uiop/package* :uiop/utility :uiop/version
+   :uiop/os :uiop/pathname :uiop/filesystem :uiop/stream :uiop/image
+   :uiop/launch-program :uiop/run-program
+   :uiop/lisp-build :uiop/configuration :uiop/backward-driver))
+
+;; Provide both lowercase and uppercase, to satisfy more implementations.
+(provide "uiop") (provide "UIOP")
+;;;; -------------------------------------------------------------------------
+;;;; Handle upgrade as forward- and backward-compatibly as possible
+;; See https://bugs.launchpad.net/asdf/+bug/485687
+
+(uiop/package:define-package :asdf/upgrade
+  (:recycle :asdf/upgrade :asdf)
+  (:use :uiop/common-lisp :uiop)
+  (:export
+   #:asdf-version #:*previous-asdf-versions* #:*asdf-version*
+   #:asdf-message #:*verbose-out*
+   #:upgrading-p #:when-upgrading #:upgrade-asdf #:defparameter*
+   #:*post-upgrade-cleanup-hook* #:cleanup-upgraded-asdf
+   ;; There will be no symbol left behind!
+   #:with-asdf-deprecation
+   #:intern*)
+  (:import-from :uiop/package #:intern* #:find-symbol*))
+(in-package :asdf/upgrade)
+
+;;; Special magic to detect if this is an upgrade
+
+(with-upgradability ()
+  (defun asdf-version ()
+    "Exported interface to the version of ASDF currently installed. A string.
+You can compare this string with e.g.: (ASDF:VERSION-SATISFIES (ASDF:ASDF-VERSION) \"3.4.5.67\")."
+    (when (find-package :asdf)
+      (or (symbol-value (find-symbol (string :*asdf-version*) :asdf))
+          (let* ((revsym (find-symbol (string :*asdf-revision*) :asdf))
+                 (rev (and revsym (boundp revsym) (symbol-value revsym))))
+            (etypecase rev
+              (string rev)
+              (cons (format nil "~{~D~^.~}" rev))
+              (null "1.0"))))))
+  ;; This (private) variable contains a list of versions of previously loaded variants of ASDF,
+  ;; from which ASDF was upgraded.
+  ;; Important: define *p-a-v* /before/ *a-v* so that they initialize correctly.
+  (defvar *previous-asdf-versions*
+    (let ((previous (asdf-version)))
+      (when previous
+        ;; Punt on upgrade from ASDF1 or ASDF2, by renaming (or deleting) the package.
+        (when (version< previous "2.27") ;; 2.27 is the first to have the :asdf3 feature.
+          (let ((away (format nil "~A-~A" :asdf previous)))
+            (rename-package :asdf away)
+            (when *load-verbose*
+              (format t "~&; Renamed old ~A package away to ~A~%" :asdf away))))
+        (list previous))))
+  ;; This public variable will be bound shortly to the currently loaded version of ASDF.
+  (defvar *asdf-version* nil)
+  ;; We need to clear systems from versions older than the one in this (private) parameter.
+  ;; The latest incompatible defclass is 2.32.13 renaming a slot in component,
+  ;; or 3.2.0.2 for CCL (incompatibly changing some superclasses).
+  ;; the latest incompatible gf change is in 3.1.7.20 (see redefined-functions below).
+  (defparameter *oldest-forward-compatible-asdf-version* "3.2.0.2")
+  ;; Semi-private variable: a designator for a stream on which to output ASDF progress messages
+  (defvar *verbose-out* nil)
+  ;; Private function by which ASDF outputs progress messages and warning messages:
+  (defun asdf-message (format-string &rest format-args)
+    (when *verbose-out* (apply 'format *verbose-out* format-string format-args)))
+  ;; Private hook for functions to run after ASDF has upgraded itself from an older variant:
+  (defvar *post-upgrade-cleanup-hook* ())
+  ;; Private function to detect whether the current upgrade counts as an incompatible
+  ;; data schema upgrade implying the need to drop data.
+  (defun upgrading-p (&optional (oldest-compatible-version *oldest-forward-compatible-asdf-version*))
+    (and *previous-asdf-versions*
+         (version< (first *previous-asdf-versions*) oldest-compatible-version)))
+  ;; Private variant of defparameter that works in presence of incompatible upgrades:
+  ;; behaves like defvar in a compatible upgrade (e.g. reloading system after simple code change),
+  ;; but behaves like defparameter if in presence of an incompatible upgrade.
+  (defmacro defparameter* (var value &optional docstring (version *oldest-forward-compatible-asdf-version*))
+    (let* ((name (string-trim "*" var))
+           (valfun (intern (format nil "%~A-~A-~A" :compute name :value))))
+      `(progn
+         (defun ,valfun () ,value)
+         (defvar ,var (,valfun) ,@(ensure-list docstring))
+         (when (upgrading-p ,version)
+           (setf ,var (,valfun))))))
+  ;; Private macro to declare sections of code that are only compiled and run when upgrading.
+  ;; The use of eval portably ensures that the code will not have adverse compile-time side-effects,
+  ;; whereas the use of handler-bind portably ensures that it will not issue warnings when it runs.
+  (defmacro when-upgrading ((&key (version *oldest-forward-compatible-asdf-version*)
+                               (upgrading-p `(upgrading-p ,version)) when) &body body)
+    "A wrapper macro for code that should only be run when upgrading a
+previously-loaded version of ASDF."
+    `(with-upgradability ()
+       (when (and ,upgrading-p ,@(when when `(,when)))
+         (handler-bind ((style-warning #'muffle-warning))
+           (eval '(progn ,@body))))))
+  ;; Only now can we safely update the version.
+  (let* (;; For bug reporting sanity, please always bump this version when you modify this file.
+         ;; Please also modify asdf.asd to reflect this change. make bump-version v=3.4.5.67.8
+         ;; can help you do these changes in synch (look at the source for documentation).
+         ;; Relying on its automation, the version is now redundantly present on top of asdf.lisp.
+         ;; "3.4" would be the general branch for major version 3, minor version 4.
+         ;; "3.4.5" would be an official release in the 3.4 branch.
+         ;; "3.4.5.67" would be a development version in the official branch, on top of 3.4.5.
+         ;; "3.4.5.0.8" would be your eighth local modification of official release 3.4.5
+         ;; "3.4.5.67.8" would be your eighth local modification of development version 3.4.5.67
+         (asdf-version "3.3.5")
+         (existing-version (asdf-version)))
+    (setf *asdf-version* asdf-version)
+    (when (and existing-version (not (equal asdf-version existing-version)))
+      (push existing-version *previous-asdf-versions*)
+      (when (or *verbose-out* *load-verbose*)
+        (format (or *verbose-out* *trace-output*)
+                (compatfmt "~&~@<; ~@;Upgrading ASDF ~@[from version ~A ~]to version ~A~@:>~%")
+                existing-version asdf-version)))))
+
+;;; Upon upgrade, specially frob some functions and classes that are being incompatibly redefined
+(when-upgrading ()
+  (let* ((previous-version (first *previous-asdf-versions*))
+         (redefined-functions ;; List of functions that changed incompatibly since 2.27:
+          ;; gf signature changed, defun that became a generic function (but not way around),
+          ;; method removed that will mess up with new ones
+          ;; (especially :around :before :after, more specific or call-next-method'ed method)
+          ;; and/or semantics otherwise modified. Oops.
+          ;; NB: it's too late to do anything about functions in UIOP!
+          ;; If you introduce some critical incompatibility there, you MUST change the function name.
+          ;; Note that we don't need do anything about functions that changed incompatibly
+          ;; from ASDF 2.26 or earlier: we wholly punt on the entire ASDF package in such an upgrade.
+          ;; Also, the strong constraints apply most importantly for functions called from
+          ;; the continuation of compiling or loading some of the code in ASDF or UIOP.
+          ;; See discussion at https://gitlab.common-lisp.net/asdf/asdf/merge_requests/36
+          ;; and at https://gitlab.common-lisp.net/asdf/asdf/-/merge_requests/141
+          `(,@(when (version< previous-version "2.31") '(#:normalize-version)) ;; pathname became &key
+            ,@(when (version< previous-version "3.1.2") '(#:component-depends-on #:input-files)) ;; crucial methods *removed* before 3.1.2
+            ,@(when (version< previous-version "3.1.7.20") '(#:find-component)))) ;; added &key registered
+         (redefined-classes
+          ;; with the old ASDF during upgrade, and many implementations bork
+          (when (or #+(or clozure mkcl) t)
+            '((#:compile-concatenated-source-op (#:operation) ())
+              (#:compile-bundle-op (#:operation) ())
+              (#:concatenate-source-op (#:operation) ())
+              (#:dll-op (#:operation) ())
+              (#:lib-op (#:operation) ())
+              (#:monolithic-compile-bundle-op (#:operation) ())
+              (#:monolithic-concatenate-source-op (#:operation) ())))))
+    (loop :for name :in redefined-functions
+      :for sym = (find-symbol* name :asdf nil)
+      :do (when sym (fmakunbound sym)))
+    (labels ((asym (x) (multiple-value-bind (s p)
+                           (if (consp x) (values (car x) (cadr x)) (values x :asdf))
+                         (find-symbol* s p nil)))
+             (asyms (l) (mapcar #'asym l)))
+      (loop :for (name superclasses slots) :in redefined-classes
+            :for sym = (find-symbol* name :asdf nil)
+            :when (and sym (find-class sym))
+              :do #+ccl (eval `(defclass ,sym ,(asyms superclasses) ,(asyms slots)))
+                  #-ccl (setf (find-class sym) nil))))) ;; mkcl
+
+;;; Self-upgrade functions
+(with-upgradability ()
+  ;; This private function is called at the end of asdf/footer and ensures that,
+  ;; *if* this loading of ASDF was an upgrade, then all registered cleanup functions will be called.
+  (defun cleanup-upgraded-asdf (&optional (old-version (first *previous-asdf-versions*)))
+    (let ((new-version (asdf-version)))
+      (unless (equal old-version new-version)
+        (push new-version *previous-asdf-versions*)
+        (when old-version
+          (if (version<= new-version old-version)
+              (error (compatfmt "~&~@<; ~@;Downgraded ASDF from version ~A to version ~A~@:>~%")
+                     old-version new-version)
+              (asdf-message (compatfmt "~&~@<; ~@;Upgraded ASDF from version ~A to version ~A~@:>~%")
+                            old-version new-version))
+          ;; In case the previous version was too old to be forward-compatible, clear systems.
+          ;; TODO: if needed, we may have to define a separate hook to run
+          ;; in case of forward-compatible upgrade.
+          ;; Or to move the tests forward-compatibility test inside each hook function?
+          (unless (version<= *oldest-forward-compatible-asdf-version* old-version)
+            (call-functions (reverse *post-upgrade-cleanup-hook*)))
+          t))))
+
+  (defun upgrade-asdf ()
+    "Try to upgrade of ASDF. If a different version was used, return T.
+   We need do that before we operate on anything that may possibly depend on ASDF."
+    (let ((*load-print* nil)
+          (*compile-print* nil))
+      (handler-bind (((or style-warning) #'muffle-warning))
+        (symbol-call :asdf :load-system :asdf :verbose nil))))
+
+  (defmacro with-asdf-deprecation ((&rest keys &key &allow-other-keys) &body body)
+    `(with-upgradability ()
+       (with-deprecation ((version-deprecation *asdf-version* ,@keys))
+         ,@body))))
+;;;; -------------------------------------------------------------------------
+;;;; Session
+
+(uiop/package:define-package :asdf/session
+  (:recycle :asdf/session :asdf/cache :asdf/component
+            :asdf/action :asdf/find-system :asdf/plan :asdf)
+  (:use :uiop/common-lisp :uiop :asdf/upgrade)
+  (:export
+   #:get-file-stamp #:compute-file-stamp #:register-file-stamp
+   #:asdf-cache #:set-asdf-cache-entry #:unset-asdf-cache-entry #:consult-asdf-cache
+   #:do-asdf-cache #:normalize-namestring
+   #:call-with-asdf-session #:with-asdf-session
+   #:*asdf-session* #:*asdf-session-class* #:session #:toplevel-asdf-session
+   #:session-cache #:forcing #:asdf-upgraded-p
+   #:visited-actions #:visiting-action-set #:visiting-action-list
+   #:total-action-count #:planned-action-count #:planned-output-action-count
+   #:clear-configuration-and-retry #:retry
+   #:operate-level
+   ;; conditions
+   #:system-definition-error ;; top level, moved here because this is the earliest place for it.
+   #:formatted-system-definition-error #:format-control #:format-arguments #:sysdef-error))
+(in-package :asdf/session)
+
+
+(with-upgradability ()
+  ;; The session variable.
+  ;; NIL when outside a session.
+  (defvar *asdf-session* nil)
+  (defparameter* *asdf-session-class* 'session
+    "The default class for sessions")
+
+  (defclass session ()
+    (;; The ASDF session cache is used to memoize some computations.
+     ;; It is instrumental in achieving:
+     ;; * Consistency in the view of the world relied on by ASDF within a given session.
+     ;;   Inconsistencies in file stamps, system definitions, etc., could cause infinite loops
+     ;;   (a.k.a. stack overflows) and other erratic behavior.
+     ;; * Speed and reliability of ASDF, with fewer side-effects from access to the filesystem, and
+     ;;   no expensive recomputations of transitive dependencies for input-files or output-files.
+     ;; * Testability of ASDF with the ability to fake timestamps without actually touching files.
+     (ancestor
+      :initform nil :initarg :ancestor :reader session-ancestor
+      :documentation "Top level session that this is part of")
+     (session-cache
+      :initform (make-hash-table :test 'equal) :initarg :session-cache :reader session-cache
+      :documentation "Memoize expensive computations")
+     (operate-level
+      :initform 0 :initarg :operate-level :accessor session-operate-level
+      :documentation "Number of nested calls to operate we're under (for toplevel session only)")
+     ;; shouldn't the below be superseded by the session-wide caching of action-status
+     ;; for (load-op "asdf") ?
+     (asdf-upgraded-p
+      :initform nil :initarg :asdf-upgraded-p :accessor asdf-upgraded-p
+      :documentation "Was ASDF already upgraded in this session - only valid for toplevel-asdf-session.")
+     (forcing
+      :initform nil :initarg :forcing :accessor forcing
+      :documentation "Forcing parameters for the session")
+     ;; Table that to actions already visited while walking the dependencies associates status
+     (visited-actions :initform (make-hash-table :test 'equal) :accessor visited-actions)
+     ;; Actions that depend on those being currently walked through, to detect circularities
+     (visiting-action-set ;; as a set
+      :initform (make-hash-table :test 'equal) :accessor visiting-action-set)
+     (visiting-action-list :initform () :accessor visiting-action-list) ;; as a list
+     ;; Counts of total actions in plan
+     (total-action-count :initform 0 :accessor total-action-count)
+     ;; Count of actions that need to be performed
+     (planned-action-count :initform 0 :accessor planned-action-count)
+     ;; Count of actions that need to be performed that have a non-empty list of output-files.
+     (planned-output-action-count :initform 0 :accessor planned-output-action-count))
+    (:documentation "An ASDF session with a cache to memoize some computations"))
+
+  (defun toplevel-asdf-session ()
+    (when *asdf-session* (or (session-ancestor *asdf-session*) *asdf-session*)))
+
+  (defun operate-level ()
+    (session-operate-level (toplevel-asdf-session)))
+
+  (defun (setf operate-level) (new-level)
+    (setf (session-operate-level (toplevel-asdf-session)) new-level))
+
+  (defun asdf-cache ()
+    (session-cache *asdf-session*))
+
+  ;; Set a session cache entry for KEY to a list of values VALUE-LIST, when inside a session.
+  ;; Return those values.
+  (defun set-asdf-cache-entry (key value-list)
+    (values-list (if *asdf-session*
+                     (setf (gethash key (asdf-cache)) value-list)
+                     value-list)))
+
+  ;; Unset the session cache entry for KEY, when inside a session.
+  (defun unset-asdf-cache-entry (key)
+    (when *asdf-session*
+      (remhash key (session-cache *asdf-session*))))
+
+  ;; Consult the session cache entry for KEY if present and in a session;
+  ;; if not present, compute it by calling the THUNK,
+  ;; and set the session cache entry accordingly, if in a session.
+  ;; Return the values from the cache and/or the thunk computation.
+  (defun consult-asdf-cache (key &optional thunk)
+    (if *asdf-session*
+        (multiple-value-bind (results foundp) (gethash key (session-cache *asdf-session*))
+          (if foundp
+              (values-list results)
+              (set-asdf-cache-entry key (multiple-value-list (call-function thunk)))))
+        (call-function thunk)))
+
+  ;; Syntactic sugar for consult-asdf-cache
+  (defmacro do-asdf-cache (key &body body)
+    `(consult-asdf-cache ,key #'(lambda () ,@body)))
+
+  ;; Compute inside a ASDF session with a cache.
+  ;; First, make sure an ASDF session is underway, by binding the session cache variable
+  ;; to a new hash-table if it's currently null (or even if it isn't, if OVERRIDE is true).
+  ;; Second, if a new session was started, establish restarts for retrying the overall computation.
+  ;; Finally, consult the cache if a KEY was specified with the THUNK as a fallback when the cache
+  ;; entry isn't found, or just call the THUNK if no KEY was specified.
+  (defun call-with-asdf-session (thunk &key override key override-cache override-forcing)
+    (let ((fun (if key #'(lambda () (consult-asdf-cache key thunk)) thunk)))
+      (if (and (not override) *asdf-session*)
+          (funcall fun)
+          (loop
+            (restart-case
+                (let ((*asdf-session*
+                       (apply 'make-instance *asdf-session-class*
+                              (when *asdf-session*
+                                `(:ancestor ,(toplevel-asdf-session)
+                                  ,@(unless override-forcing
+                                      `(:forcing ,(forcing *asdf-session*)))
+                                  ,@(unless override-cache
+                                      `(:session-cache ,(session-cache *asdf-session*))))))))
+                  (return (funcall fun)))
+              (retry ()
+                :report (lambda (s)
+                          (format s (compatfmt "~@<Retry ASDF operation.~@:>"))))
+              (clear-configuration-and-retry ()
+                :report (lambda (s)
+                          (format s (compatfmt "~@<Retry ASDF operation after resetting the configuration.~@:>")))
+                (clrhash (session-cache *asdf-session*))
+                (clear-configuration)))))))
+
+  ;; Syntactic sugar for call-with-asdf-session
+  (defmacro with-asdf-session ((&key key override override-cache override-forcing) &body body)
+    `(call-with-asdf-session
+      #'(lambda () ,@body)
+      :override ,override :key ,key
+      :override-cache ,override-cache :override-forcing ,override-forcing))
+
+
+  ;;; Define specific accessor for file (date) stamp.
+
+  ;; Normalize a namestring for use as a key in the session cache.
+  (defun normalize-namestring (pathname)
+    (let ((resolved (resolve-symlinks*
+                     (ensure-absolute-pathname
+                      (physicalize-pathname pathname)
+                      'get-pathname-defaults))))
+      (with-pathname-defaults () (namestring resolved))))
+
+  ;; Compute the file stamp for a normalized namestring
+  (defun compute-file-stamp (normalized-namestring)
+    (with-pathname-defaults ()
+      (or (safe-file-write-date normalized-namestring) t)))
+
+  ;; Override the time STAMP associated to a given FILE in the session cache.
+  ;; If no STAMP is specified, recompute a new one from the filesystem.
+  (defun register-file-stamp (file &optional (stamp nil stampp))
+    (let* ((namestring (normalize-namestring file))
+           (stamp (if stampp stamp (compute-file-stamp namestring))))
+      (set-asdf-cache-entry `(get-file-stamp ,namestring) (list stamp))))
+
+  ;; Get or compute a memoized stamp for given FILE from the session cache.
+  (defun get-file-stamp (file)
+    (when file
+      (let ((namestring (normalize-namestring file)))
+        (do-asdf-cache `(get-file-stamp ,namestring) (compute-file-stamp namestring)))))
+
+
+  ;;; Conditions
+
+  (define-condition system-definition-error (error) ()
+    ;; [this use of :report should be redundant, but unfortunately it's not.
+    ;; cmucl's lisp::output-instance prefers the kernel:slot-class-print-function
+    ;; over print-object; this is always conditions::%print-condition for
+    ;; condition objects, which in turn does inheritance of :report options at
+    ;; run-time.  fortunately, inheritance means we only need this kludge here in
+    ;; order to fix all conditions that build on it.  -- rgr, 28-Jul-02.]
+    #+cmucl (:report print-object))
+
+  (define-condition formatted-system-definition-error (system-definition-error)
+    ((format-control :initarg :format-control :reader format-control)
+     (format-arguments :initarg :format-arguments :reader format-arguments))
+    (:report (lambda (c s)
+               (apply 'format s (format-control c) (format-arguments c)))))
+
+  (defun sysdef-error (format &rest arguments)
+    (error 'formatted-system-definition-error :format-control
+           format :format-arguments arguments)))
+;;;; -------------------------------------------------------------------------
+;;;; Components
+
+(uiop/package:define-package :asdf/component
+  (:recycle :asdf/component :asdf/find-component :asdf)
+  (:use :uiop/common-lisp :uiop :asdf/upgrade :asdf/session)
+  (:export
+   #:component #:component-find-path
+   #:find-component ;; methods defined in find-component
+   #:component-name #:component-pathname #:component-relative-pathname
+   #:component-parent #:component-system #:component-parent-pathname
+   #:child-component #:parent-component #:module
+   #:file-component
+   #:source-file #:c-source-file #:java-source-file
+   #:static-file #:doc-file #:html-file
+   #:file-type
+   #:source-file-type #:source-file-explicit-type ;; backward-compatibility
+   #:component-in-order-to #:component-sideway-dependencies
+   #:component-if-feature #:around-compile-hook
+   #:component-description #:component-long-description
+   #:component-version #:version-satisfies
+   #:component-inline-methods ;; backward-compatibility only. DO NOT USE!
+   #:component-operation-times ;; For internal use only.
+   ;; portable ASDF encoding and implementation-specific external-format
+   #:component-external-format #:component-encoding
+   #:component-children-by-name #:component-children #:compute-children-by-name
+   #:component-build-operation
+   #:module-default-component-class
+   #:module-components ;; backward-compatibility. DO NOT USE.
+   #:sub-components
+
+   ;; conditions
+   #:duplicate-names
+
+   ;; Internals we'd like to share with the ASDF package, especially for upgrade purposes
+   #:name #:version #:description #:long-description #:author #:maintainer #:licence
+   #:components-by-name #:components #:children #:children-by-name
+   #:default-component-class #:source-file
+   #:defsystem-depends-on ; This symbol retained for backward compatibility.
+   #:sideway-dependencies #:if-feature #:in-order-to #:inline-methods
+   #:relative-pathname #:absolute-pathname #:operation-times #:around-compile
+   #:%encoding #:properties #:component-properties #:parent))
+(in-package :asdf/component)
+
+(with-upgradability ()
+  (defgeneric component-name (component)
+    (:documentation "Name of the COMPONENT, unique relative to its parent"))
+  (defgeneric component-system (component)
+    (:documentation "Top-level system containing the COMPONENT"))
+  (defgeneric component-pathname (component)
+    (:documentation "Pathname of the COMPONENT if any, or NIL."))
+  (defgeneric component-relative-pathname (component)
+    ;; in ASDF4, rename that to component-specified-pathname ?
+    (:documentation "Specified pathname of the COMPONENT,
+intended to be merged with the pathname of that component's parent if any, using merged-pathnames*.
+Despite the function's name, the return value can be an absolute pathname, in which case the merge
+will leave it unmodified."))
+  (defgeneric component-external-format (component)
+    (:documentation "The external-format of the COMPONENT.
+By default, deduced from the COMPONENT-ENCODING."))
+  (defgeneric component-encoding (component)
+    (:documentation "The encoding of the COMPONENT. By default, only :utf-8 is supported.
+Use asdf-encodings to support more encodings."))
+  (defgeneric version-satisfies (component version)
+    (:documentation "Check whether a COMPONENT satisfies the constraint of being at least as recent
+as the specified VERSION, which must be a string of dot-separated natural numbers, or NIL."))
+  (defgeneric component-version (component)
+    (:documentation "Return the version of a COMPONENT, which must be a string of dot-separated
+natural numbers, or NIL."))
+  (defgeneric (setf component-version) (new-version component)
+    (:documentation "Updates the version of a COMPONENT, which must be a string of dot-separated
+natural numbers, or NIL."))
+  (defgeneric component-parent (component)
+    (:documentation "The parent of a child COMPONENT,
+or NIL for top-level components (a.k.a. systems)"))
+  ;; NIL is a designator for the absence of a component, in which case the parent is also absent.
+  (defmethod component-parent ((component null)) nil)
+
+  ;; Deprecated: Backward compatible way of computing the FILE-TYPE of a component.
+  (with-asdf-deprecation (:style-warning "3.4")
+   (defgeneric source-file-type (component system)
+     (:documentation "DEPRECATED. Use the FILE-TYPE of a COMPONENT instead.")))
+
+  (define-condition duplicate-names (system-definition-error)
+    ((name :initarg :name :reader duplicate-names-name))
+    (:report (lambda (c s)
+               (format s (compatfmt "~@<Error while defining system: multiple components are given same name ~S~@:>")
+                       (duplicate-names-name c))))))
+
+
+(with-upgradability ()
+  (defclass component ()
+    ((name :accessor component-name :initarg :name :type string :documentation
+           "Component name: designator for a string composed of portable pathname characters")
+     ;; We might want to constrain version with
+     ;; :type (and string (satisfies parse-version))
+     ;; but we cannot until we fix all systems that don't use it correctly!
+     (version :accessor component-version :initarg :version :initform nil)
+     (description :accessor component-description :initarg :description :initform nil)
+     (long-description :accessor component-long-description :initarg :long-description :initform nil)
+     (sideway-dependencies :accessor component-sideway-dependencies :initform nil)
+     (if-feature :accessor component-if-feature :initform nil :initarg :if-feature)
+     ;; In the ASDF object model, dependencies exist between *actions*,
+     ;; where an action is a pair of an operation and a component.
+     ;; Dependencies are represented as alists of operations
+     ;; to a list where each entry is a pair of an operation and a list of component specifiers.
+     ;; Up until ASDF 2.26.9, there used to be two kinds of dependencies:
+     ;; in-order-to and do-first, each stored in its own slot. Now there is only in-order-to.
+     ;; in-order-to used to represent things that modify the filesystem (such as compiling a fasl)
+     ;; and do-first things that modify the current image (such as loading a fasl).
+     ;; These are now unified because we now correctly propagate timestamps between dependencies.
+     ;; Happily, no one seems to have used do-first too much (especially since until ASDF 2.017,
+     ;; anything you specified was overridden by ASDF itself anyway), but the name in-order-to remains.
+     ;; The names are bad, but they have been the official API since Dan Barlow's ASDF 1.52!
+     ;; LispWorks's defsystem has caused-by and requires for in-order-to and do-first respectively.
+     ;; Maybe rename the slots in ASDF? But that's not very backward-compatible.
+     ;; See our ASDF 2 paper for more complete explanations.
+     (in-order-to :initform nil :initarg :in-order-to
+                  :accessor component-in-order-to)
+     ;; Methods defined using the "inline" style inside a defsystem form:
+     ;; we store them here so we can delete them when the system is re-evaluated.
+     (inline-methods :accessor component-inline-methods :initform nil)
+     ;; ASDF4: rename it from relative-pathname to specified-pathname. It need not be relative.
+     ;; There is no initform and no direct accessor for this specified pathname,
+     ;; so we only access the information through appropriate methods, after it has been processed.
+     ;; Unhappily, some braindead systems directly access the slot. Make them stop before ASDF4.
+     (relative-pathname :initarg :pathname)
+     ;; The absolute-pathname is computed based on relative-pathname and parent pathname.
+     ;; The slot is but a cache used by component-pathname.
+     (absolute-pathname)
+     (operation-times :initform (make-hash-table)
+                      :accessor component-operation-times)
+     (around-compile :initarg :around-compile)
+     ;; Properties are for backward-compatibility with ASDF2 only. DO NOT USE!
+     (properties :accessor component-properties :initarg :properties
+                 :initform nil)
+     (%encoding :accessor %component-encoding :initform nil :initarg :encoding)
+     ;; For backward-compatibility, this slot is part of component rather than of child-component. ASDF4: stop it.
+     (parent :initarg :parent :initform nil :reader component-parent)
+     (build-operation
+      :initarg :build-operation :initform nil :reader component-build-operation)
+     ;; Cache for ADDITIONAL-INPUT-FILES function.
+     (additional-input-files :accessor %additional-input-files :initform nil))
+    (:documentation "Base class for all components of a build"))
+
+  (defgeneric find-component (base path &key registered)
+    (:documentation "Find a component by resolving the PATH starting from BASE parent.
+If REGISTERED is true, only search currently registered systems."))
+
+  (defun component-find-path (component)
+    "Return a path from a root system to the COMPONENT.
+The return value is a list of component NAMES; a list of strings."
+    (check-type component (or null component))
+    (reverse
+     (loop :for c = component :then (component-parent c)
+           :while c :collect (component-name c))))
+
+  (defmethod print-object ((c component) stream)
+    (print-unreadable-object (c stream :type t :identity nil)
+      (format stream "~{~S~^ ~}" (component-find-path c))))
+
+  (defmethod component-system ((component component))
+    (if-let (system (component-parent component))
+      (component-system system)
+      component)))
+
+
+;;;; Component hierarchy within a system
+;; The tree typically but not necessarily follows the filesystem hierarchy.
+(with-upgradability ()
+  (defclass child-component (component) ()
+    (:documentation "A CHILD-COMPONENT is a COMPONENT that may be part of
+a PARENT-COMPONENT."))
+
+  (defclass file-component (child-component)
+    ((type :accessor file-type :initarg :type)) ; no default
+    (:documentation "a COMPONENT that represents a file"))
+  (defclass source-file (file-component)
+    ((type :accessor source-file-explicit-type ;; backward-compatibility
+           :initform nil))) ;; NB: many systems have come to rely on this default.
+  (defclass c-source-file (source-file)
+    ((type :initform "c")))
+  (defclass java-source-file (source-file)
+    ((type :initform "java")))
+  (defclass static-file (source-file)
+    ((type :initform nil))
+    (:documentation "Component for a file to be included as is in the build output"))
+  (defclass doc-file (static-file) ())
+  (defclass html-file (doc-file)
+    ((type :initform "html")))
+
+  (defclass parent-component (component)
+    ((children
+      :initform nil
+      :initarg :components
+      :reader module-components ; backward-compatibility
+      :accessor component-children)
+     (children-by-name
+      :reader module-components-by-name ; backward-compatibility
+      :accessor component-children-by-name)
+     (default-component-class
+      :initform nil
+      :initarg :default-component-class
+      :accessor module-default-component-class))
+  (:documentation "A PARENT-COMPONENT is a component that may have children.")))
+
+(with-upgradability ()
+  ;; (Private) Function that given a PARENT component,
+  ;; the list of children of which has been initialized,
+  ;; compute the hash-table in slot children-by-name that allows to retrieve its children by name.
+  ;; If ONLY-IF-NEEDED-P is defined, skip any (re)computation if the slot is already populated.
+  (defun compute-children-by-name (parent &key only-if-needed-p)
+    (unless (and only-if-needed-p (slot-boundp parent 'children-by-name))
+      (let ((hash (make-hash-table :test 'equal)))
+        (setf (component-children-by-name parent) hash)
+        (loop :for c :in (component-children parent)
+              :for name = (component-name c)
+              :for previous = (gethash name hash)
+              :do (when previous (error 'duplicate-names :name name))
+                  (setf (gethash name hash) c))
+        hash))))
+
+(with-upgradability ()
+  (defclass module (child-component parent-component)
+    (#+clisp (components)) ;; backward compatibility during upgrade only
+    (:documentation "A module is a intermediate component with both a parent and children,
+typically but not necessarily representing the files in a subdirectory of the build source.")))
+
+
+;;;; component pathnames
+(with-upgradability ()
+  (defgeneric component-parent-pathname (component)
+    (:documentation "The pathname of the COMPONENT's parent, if any, or NIL"))
+  (defmethod component-parent-pathname (component)
+    (component-pathname (component-parent component)))
+
+  ;; The default method for component-pathname tries to extract a cached precomputed
+  ;; absolute-pathname from the relevant slot, and if not, computes it by merging the
+  ;; component-relative-pathname (which should be component-specified-pathname, it can be absolute)
+  ;; with the directory of the component-parent-pathname.
+  (defmethod component-pathname ((component component))
+    (if (slot-boundp component 'absolute-pathname)
+        (slot-value component 'absolute-pathname)
+        (let ((pathname
+                (merge-pathnames*
+                 (component-relative-pathname component)
+                 (pathname-directory-pathname (component-parent-pathname component)))))
+          (unless (or (null pathname) (absolute-pathname-p pathname))
+            (error (compatfmt "~@<Invalid relative pathname ~S for component ~S~@:>")
+                   pathname (component-find-path component)))
+          (setf (slot-value component 'absolute-pathname) pathname)
+          pathname)))
+
+  ;; Default method for component-relative-pathname:
+  ;; combine the contents of slot relative-pathname (from specified initarg :pathname)
+  ;; with the appropriate source-file-type, which defaults to the file-type of the component.
+  (defmethod component-relative-pathname ((component component))
+    ;; SOURCE-FILE-TYPE below is strictly for backward-compatibility with ASDF1.
+    ;; We ought to be able to extract this from the component alone with FILE-TYPE.
+    ;; TODO: track who uses it in Quicklisp, and have them not use it anymore;
+    ;; maybe issue a WARNING (then eventually CERROR) if the two methods diverge?
+    (parse-unix-namestring
+     (or (and (slot-boundp component 'relative-pathname)
+              (slot-value component 'relative-pathname))
+         (component-name component))
+     :want-relative t
+     :type (source-file-type component (component-system component))
+     :defaults (component-parent-pathname component)))
+
+  (defmethod source-file-type ((component parent-component) (system parent-component))
+    :directory)
+
+  (defmethod source-file-type ((component file-component) (system parent-component))
+    (file-type component)))
+
+
+;;;; Encodings
+(with-upgradability ()
+  (defmethod component-encoding ((c component))
+    (or (loop :for x = c :then (component-parent x)
+              :while x :thereis (%component-encoding x))
+        (detect-encoding (component-pathname c))))
+
+  (defmethod component-external-format ((c component))
+    (encoding-external-format (component-encoding c))))
+
+
+;;;; around-compile-hook
+(with-upgradability ()
+  (defgeneric around-compile-hook (component)
+    (:documentation "An optional hook function that will be called with one argument, a thunk.
+The hook function must call the thunk, that will compile code from the component, and may or may not
+also evaluate the compiled results. The hook function may establish dynamic variable bindings around
+this compilation, or check its results, etc."))
+  (defmethod around-compile-hook ((c component))
+    (cond
+      ((slot-boundp c 'around-compile)
+       (slot-value c 'around-compile))
+      ((component-parent c)
+       (around-compile-hook (component-parent c))))))
+
+
+;;;; version-satisfies
+(with-upgradability ()
+  ;; short-circuit testing of null version specifications.
+  ;; this is an all-pass, without warning
+  (defmethod version-satisfies :around ((c t) (version null))
+    t)
+  (defmethod version-satisfies ((c component) version)
+    (unless (and version (slot-boundp c 'version) (component-version c))
+      (when version
+        (warn "Requested version ~S but ~S has no version" version c))
+      (return-from version-satisfies nil))
+    (version-satisfies (component-version c) version))
+
+  (defmethod version-satisfies ((cver string) version)
+    (version<= version cver)))
+
+
+;;; all sub-components (of a given type)
+(with-upgradability ()
+  (defun sub-components (component &key (type t))
+    "Compute the transitive sub-components of given COMPONENT that are of given TYPE"
+    (while-collecting (c)
+      (labels ((recurse (x)
+                 (when (if-let (it (component-if-feature x)) (featurep it) t)
+                   (when (typep x type)
+                     (c x))
+                   (when (typep x 'parent-component)
+                     (map () #'recurse (component-children x))))))
+        (recurse component)))))
+
+;;;; -------------------------------------------------------------------------
+;;;; Operations
+
+(uiop/package:define-package :asdf/operation
+  (:recycle :asdf/operation :asdf/action :asdf) ;; asdf/action for FEATURE pre 2.31.5.
+  (:use :uiop/common-lisp :uiop :asdf/upgrade :asdf/session)
+  (:export
+   #:operation
+   #:*operations* #:make-operation #:find-operation
+   #:feature)) ;; TODO: stop exporting the deprecated FEATURE feature.
+(in-package :asdf/operation)
+
+;;; Operation Classes
+(when-upgrading (:version "2.27" :when (find-class 'operation nil))
+  ;; override any obsolete shared-initialize method when upgrading from ASDF2.
+  (defmethod shared-initialize :after ((o operation) (slot-names t) &key)
+    (values)))
+
+(with-upgradability ()
+  (defclass operation ()
+    ()
+    (:documentation "The base class for all ASDF operations.
+
+ASDF does NOT and never did distinguish between multiple operations of the same class.
+Therefore, all slots of all operations MUST have :allocation :class and no initargs. No exceptions.
+"))
+
+  (defvar *in-make-operation* nil)
+
+  (defun check-operation-constructor ()
+    "Enforce that OPERATION instances must be created with MAKE-OPERATION."
+    (unless *in-make-operation*
+      (sysdef-error "OPERATION instances must only be created through MAKE-OPERATION.")))
+
+  (defmethod print-object ((o operation) stream)
+    (print-unreadable-object (o stream :type t :identity nil)))
+
+  ;;; Override previous methods (from 3.1.7 and earlier) and add proper error checking.
+  #-genera ;; Genera adds its own system initargs, e.g. clos-internals:storage-area 8
+  (defmethod initialize-instance :after ((o operation) &rest initargs &key &allow-other-keys)
+    (unless (null initargs)
+      (parameter-error "~S does not accept initargs" 'operation))))
+
+
+;;; make-operation, find-operation
+
+(with-upgradability ()
+  ;; A table to memoize instances of a given operation. There shall be only one.
+  (defparameter* *operations* (make-hash-table :test 'equal))
+
+  ;; A memoizing way of creating instances of operation.
+  (defun make-operation (operation-class)
+    "This function creates and memoizes an instance of OPERATION-CLASS.
+All operation instances MUST be created through this function.
+
+Use of INITARGS is not supported at this time."
+    (let ((class (coerce-class operation-class
+                               :package :asdf/interface :super 'operation :error 'sysdef-error))
+          (*in-make-operation* t))
+      (ensure-gethash class *operations* `(make-instance ,class))))
+
+  ;; This function is mostly for backward and forward compatibility:
+  ;; operations used to preserve the operation-original-initargs of the context,
+  ;; and may in the future preserve some operation-canonical-initargs.
+  ;; Still, the treatment of NIL as a disabling context is useful in some cases.
+  (defgeneric find-operation (context spec)
+    (:documentation "Find an operation by resolving the SPEC in the CONTEXT"))
+  (defmethod find-operation ((context t) (spec operation))
+    spec)
+  (defmethod find-operation ((context t) (spec symbol))
+    (when spec ;; NIL designates itself, i.e. absence of operation
+      (make-operation spec))) ;; TODO: preserve the (operation-canonical-initargs context)
+  (defmethod find-operation ((context t) (spec string))
+    (make-operation spec))) ;; TODO: preserve the (operation-canonical-initargs context)
+
+;;;; -------------------------------------------------------------------------
+;;;; Systems
+
+(uiop/package:define-package :asdf/system
+  (:recycle :asdf :asdf/system :asdf/find-system)
+  (:use :uiop/common-lisp :uiop :asdf/upgrade :asdf/session :asdf/component)
+  (:export
+   #:system #:proto-system #:undefined-system #:reset-system-class
+   #:system-source-file #:system-source-directory #:system-relative-pathname
+   #:system-description #:system-long-description
+   #:system-author #:system-maintainer #:system-licence #:system-license
+   #:system-version
+   #:definition-dependency-list #:definition-dependency-set #:system-defsystem-depends-on
+   #:system-depends-on #:system-weakly-depends-on
+   #:component-build-pathname #:build-pathname
+   #:component-entry-point #:entry-point
+   #:homepage #:system-homepage
+   #:bug-tracker #:system-bug-tracker
+   #:mailto #:system-mailto
+   #:long-name #:system-long-name
+   #:source-control #:system-source-control
+   #:coerce-name #:primary-system-name #:primary-system-p #:coerce-filename
+   #:find-system #:builtin-system-p)) ;; forward-reference, defined in find-system
+(in-package :asdf/system)
+
+(with-upgradability ()
+  ;; The method is actually defined in asdf/find-system,
+  ;; but we declare the function here to avoid a forward reference.
+  (defgeneric find-system (system &optional error-p)
+    (:documentation "Given a system designator, find the actual corresponding system object.
+If no system is found, then signal an error if ERROR-P is true (the default), or else return NIL.
+A system designator is usually a string (conventionally all lowercase) or a symbol, designating
+the same system as its downcased name; it can also be a system object (designating itself)."))
+
+  (defgeneric system-source-file (system)
+    (:documentation "Return the source file in which system is defined."))
+
+  ;; This is bad design, but was the easiest kluge I found to let the user specify that
+  ;; some special actions create outputs at locations controled by the user that are not affected
+  ;; by the usual output-translations.
+  ;; TODO: Fix operate to stop passing flags to operation (which in the current design shouldn't
+  ;; have any flags, since the stamp cache, etc., can't distinguish them), and instead insert
+  ;; *there* the ability of specifying special output paths, not in the system definition.
+  (defgeneric component-build-pathname (component)
+    (:documentation "The COMPONENT-BUILD-PATHNAME, when defined and not null, specifies the
+output pathname for the action using the COMPONENT-BUILD-OPERATION.
+
+NB: This interface is subject to change. Please contact ASDF maintainers if you use it."))
+
+  ;; TODO: Should this have been made a SYSTEM-ENTRY-POINT instead?
+  (defgeneric component-entry-point (component)
+    (:documentation "The COMPONENT-ENTRY-POINT, when defined, specifies what function to call
+(with no argument) when running an image dumped from the COMPONENT.
+
+NB: This interface is subject to change. Please contact ASDF maintainers if you use it."))
+
+  (defmethod component-entry-point ((c component))
+    nil))
+
+
+;;;; The system class
+
+(with-upgradability ()
+  (defclass proto-system () ; slots to keep when resetting a system
+    ;; To preserve identity for all objects, we'd need keep the components slots
+    ;; but also to modify parse-component-form to reset the recycled objects.
+    ((name)
+     (source-file)
+     ;; These two slots contains the *inferred* dependencies of define-op,
+     ;; from loading the .asd file, as list and as set.
+     (definition-dependency-list
+         :initform nil :accessor definition-dependency-list)
+     (definition-dependency-set
+         :initform (list-to-hash-set nil) :accessor definition-dependency-set))
+    (:documentation "PROTO-SYSTEM defines the elements of identity that are preserved when
+a SYSTEM is redefined and its class is modified."))
+
+  (defclass system (module proto-system)
+    ;; Backward-compatibility: inherit from module. ASDF4: only inherit from parent-component.
+    (;; {,long-}description is now inherited from component, but we add the legacy accessors
+     (description :writer (setf system-description))
+     (long-description :writer (setf system-long-description))
+     (author :writer (setf system-author) :initarg :author :initform nil)
+     (maintainer :writer (setf system-maintainer) :initarg :maintainer :initform nil)
+     (licence :writer (setf system-licence) :initarg :licence
+              :writer (setf system-license) :initarg :license
+              :initform nil)
+     (homepage :writer (setf system-homepage) :initarg :homepage :initform nil)
+     (bug-tracker :writer (setf system-bug-tracker) :initarg :bug-tracker :initform nil)
+     (mailto :writer (setf system-mailto) :initarg :mailto :initform nil)
+     (long-name :writer (setf system-long-name) :initarg :long-name :initform nil)
+     ;; Conventions for this slot aren't clear yet as of ASDF 2.27, but whenever they are, they will be enforced.
+     ;; I'm introducing the slot before the conventions are set for maximum compatibility.
+     (source-control :writer (setf system-source-control) :initarg :source-control :initform nil)
+
+     (builtin-system-p :accessor builtin-system-p :initform nil :initarg :builtin-system-p)
+     (build-pathname
+      :initform nil :initarg :build-pathname :accessor component-build-pathname)
+     (entry-point
+      :initform nil :initarg :entry-point :accessor component-entry-point)
+     (source-file :initform nil :initarg :source-file :accessor system-source-file)
+     ;; This slot contains the *declared* defsystem-depends-on dependencies
+     (defsystem-depends-on :reader system-defsystem-depends-on :initarg :defsystem-depends-on
+                           :initform nil)
+     ;; these two are specially set in parse-component-form, so have no :INITARGs.
+     (depends-on :reader system-depends-on :initform nil)
+     (weakly-depends-on :reader system-weakly-depends-on :initform nil))
+    (:documentation "SYSTEM is the base class for top-level components that users may request
+ASDF to build."))
+
+  (defclass undefined-system (system) ()
+    (:documentation "System that was not defined yet."))
+
+  (defun reset-system-class (system new-class &rest keys &key &allow-other-keys)
+    "Erase any data from a SYSTEM except its basic identity, then reinitialize it
+based on supplied KEYS."
+    (change-class (change-class system 'proto-system) new-class)
+    (apply 'reinitialize-instance system keys)))
+
+
+;;; Canonicalizing system names
+
+(with-upgradability ()
+  (defun coerce-name (name)
+    "Given a designator for a component NAME, return the name as a string.
+The designator can be a COMPONENT (designing its name; note that a SYSTEM is a component),
+a SYMBOL (designing its name, downcased), or a STRING (designing itself)."
+    (typecase name
+      (component (component-name name))
+      (symbol (string-downcase name))
+      (string name)
+      (t (sysdef-error (compatfmt "~@<Invalid component designator: ~3i~_~A~@:>") name))))
+
+  (defun primary-system-name (system-designator)
+    "Given a system designator NAME, return the name of the corresponding
+primary system, after which the .asd file in which it is defined is named.
+If given a string or symbol (to downcase), do it syntactically
+ by stripping anything from the first slash on.
+If given a component, do it semantically by extracting
+the system-primary-system-name of its system from its source-file if any,
+falling back to the syntactic criterion if none."
+    (etypecase system-designator
+      (string (if-let (p (position #\/ system-designator))
+                (subseq system-designator 0 p) system-designator))
+      (symbol (primary-system-name (coerce-name system-designator)))
+      (component (let* ((system (component-system system-designator))
+                        (source-file (physicalize-pathname (system-source-file system))))
+                   (if source-file
+                       (and (equal (pathname-type source-file) "asd")
+                            (pathname-name source-file))
+                       (primary-system-name (component-name system)))))))
+
+  (defun primary-system-p (system)
+    "Given a system designator SYSTEM, return T if it designates a primary system, or else NIL.
+If given a string, do it syntactically and return true if the name does not contain a slash.
+If given a symbol, downcase to a string then fallback to previous case (NB: for NIL return T).
+If given a component, do it semantically and return T if it's a SYSTEM and its primary-system-name
+is the same as its component-name."
+    (etypecase system
+      (string (not (find #\/ system)))
+      (symbol (primary-system-p (coerce-name system)))
+      (component (and (typep system 'system)
+                      (equal (component-name system) (primary-system-name system))))))
+
+  (defun coerce-filename (name)
+    "Coerce a system designator NAME into a string suitable as a filename component.
+The (current) transformation is to replace characters /:\\ each by --,
+the former being forbidden in a filename component.
+NB: The onus is unhappily on the user to avoid clashes."
+    (frob-substrings (coerce-name name) '("/" ":" "\\") "--")))
+
+
+;;; System virtual slot readers, recursing to the primary system if needed.
+(with-upgradability ()
+  (defvar *system-virtual-slots* '(long-name description long-description
+                                   author maintainer mailto
+                                   homepage source-control
+                                   licence version bug-tracker)
+    "The list of system virtual slot names.")
+  (defun system-virtual-slot-value (system slot-name)
+    "Return SYSTEM's virtual SLOT-NAME value.
+If SYSTEM's SLOT-NAME value is NIL and SYSTEM is a secondary system, look in
+the primary one."
+    (or (slot-value system slot-name)
+        (unless (primary-system-p system)
+          (slot-value (find-system (primary-system-name system))
+                      slot-name))))
+  (defmacro define-system-virtual-slot-reader (slot-name)
+    (let ((name (intern (strcat (string :system-) (string slot-name)))))
+      `(progn
+         (fmakunbound ',name) ;; These were gf from defgeneric before 3.3.2.11
+         (declaim (notinline ,name))
+         (defun ,name (system) (system-virtual-slot-value system ',slot-name)))))
+  (defmacro define-system-virtual-slot-readers ()
+    `(progn ,@(mapcar (lambda (slot-name)
+                        `(define-system-virtual-slot-reader ,slot-name))
+                *system-virtual-slots*)))
+  (define-system-virtual-slot-readers)
+  (defun system-license (system)
+    (system-virtual-slot-value system 'licence)))
+
+
+;;;; Pathnames
+
+(with-upgradability ()
+  ;; Resolve a system designator to a system before extracting its system-source-file
+  (defmethod system-source-file ((system-name string))
+    (system-source-file (find-system system-name)))
+  (defmethod system-source-file ((system-name symbol))
+    (when system-name
+      (system-source-file (find-system system-name))))
+
+  (defun system-source-directory (system-designator)
+    "Return a pathname object corresponding to the directory
+in which the system specification (.asd file) is located."
+    (pathname-directory-pathname (system-source-file system-designator)))
+
+  (defun system-relative-pathname (system name &key type)
+    "Given a SYSTEM, and a (Unix-style relative path) NAME of a file (or directory) of given TYPE,
+return the absolute pathname of a corresponding file under that system's source code pathname."
+    (subpathname (system-source-directory system) name :type type))
+
+  (defmethod component-pathname ((system system))
+    "Given a SYSTEM, and a (Unix-style relative path) NAME of a file (or directory) of given TYPE,
+return the absolute pathname of a corresponding file under that system's source code pathname."
+    (let ((pathname (or (call-next-method) (system-source-directory system))))
+      (unless (and (slot-boundp system 'relative-pathname) ;; backward-compatibility with ASDF1-age
+                   (slot-value system 'relative-pathname)) ;; systems that directly access this slot.
+        (setf (slot-value system 'relative-pathname) pathname))
+      pathname))
+
+  ;; The default method of component-relative-pathname for a system:
+  ;; if a pathname was specified in the .asd file, it must be relative to the .asd file
+  ;; (actually, to its truename* if *resolve-symlinks* it true, the default).
+  ;; The method will return an *absolute* pathname, once again showing that the historical name
+  ;; component-relative-pathname is misleading and should have been component-specified-pathname.
+  (defmethod component-relative-pathname ((system system))
+    (parse-unix-namestring
+     (and (slot-boundp system 'relative-pathname)
+          (slot-value system 'relative-pathname))
+     :want-relative t
+     :type :directory
+     :ensure-absolute t
+     :defaults (system-source-directory system)))
+
+  ;; A system has no parent; if some method wants to make a path "relative to its parent",
+  ;; it will instead be relative to the system itself.
+  (defmethod component-parent-pathname ((system system))
+    (system-source-directory system))
+
+  ;; Most components don't have a specified component-build-pathname, and therefore
+  ;; no magic redirection of their output that disregards the output-translations.
+  (defmethod component-build-pathname ((c component))
+    nil))
+
+;;;; -------------------------------------------------------------------------
+;;;; Finding systems
+
+(uiop/package:define-package :asdf/system-registry
+  (:recycle :asdf/system-registry :asdf/find-system :asdf)
+  (:use :uiop/common-lisp :uiop :asdf/upgrade
+    :asdf/session :asdf/component :asdf/system)
+  (:export
+   #:remove-entry-from-registry #:coerce-entry-to-directory
+   #:registered-system #:register-system
+   #:registered-systems* #:registered-systems
+   #:clear-system #:map-systems
+   #:*system-definition-search-functions* #:search-for-system-definition
+   #:*central-registry* #:probe-asd #:sysdef-central-registry-search
+   #:contrib-sysdef-search #:sysdef-find-asdf ;; backward compatibility symbols, functions removed
+   #:sysdef-preloaded-system-search #:register-preloaded-system #:*preloaded-systems*
+   #:find-system-if-being-defined #:mark-component-preloaded ;; forward references to asdf/find-system
+   #:sysdef-immutable-system-search #:register-immutable-system #:*immutable-systems*
+   #:*registered-systems* #:clear-registered-systems
+   ;; defined in source-registry, but specially mentioned here:
+   #:sysdef-source-registry-search))
+(in-package :asdf/system-registry)
+
+(with-upgradability ()
+  ;;; Registry of Defined Systems
+
+  (defvar *registered-systems* (make-hash-table :test 'equal)
+    "This is a hash table whose keys are strings -- the names of systems --
+and whose values are systems.
+A system is referred to as \"registered\" if it is present in this table.")
+
+  (defun registered-system (name)
+    "Return a system of given NAME that was registered already,
+if such a system exists.  NAME is a system designator, to be
+normalized by COERCE-NAME. The value returned is a system object,
+or NIL if not found."
+    (gethash (coerce-name name) *registered-systems*))
+
+  (defun registered-systems* ()
+    "Return a list containing every registered system (as a system object)."
+    (loop :for registered :being :the :hash-values :of *registered-systems*
+          :collect registered))
+
+  (defun registered-systems ()
+    "Return a list of the names of every registered system."
+    (mapcar 'coerce-name (registered-systems*)))
+
+  (defun register-system (system)
+    "Given a SYSTEM object, register it."
+    (check-type system system)
+    (let ((name (component-name system)))
+      (check-type name string)
+      (asdf-message (compatfmt "~&~@<; ~@;Registering system ~3i~_~A~@:>~%") name)
+      (setf (gethash name *registered-systems*) system)))
+
+  (defun map-systems (fn)
+    "Apply FN to each defined system.
+
+FN should be a function of one argument. It will be
+called with an object of type asdf:system."
+    (loop :for registered :being :the :hash-values :of *registered-systems*
+          :do (funcall fn registered)))
+
+
+  ;;; Preloaded systems: in the image even if you can't find source files backing them.
+
+  (defvar *preloaded-systems* (make-hash-table :test 'equal)
+    "Registration table for preloaded systems.")
+
+  (declaim (ftype (function (t) t) mark-component-preloaded)) ; defined in asdf/find-system
+
+  (defun make-preloaded-system (name keys)
+    "Make a preloaded system of given NAME with build information from KEYS"
+    (let ((system (apply 'make-instance (getf keys :class 'system)
+                         :name name :source-file (getf keys :source-file)
+                         (remove-plist-keys '(:class :name :source-file) keys))))
+      (mark-component-preloaded system)
+      system))
+
+  (defun sysdef-preloaded-system-search (requested)
+    "If REQUESTED names a system registered as preloaded, return a new system
+with its registration information."
+    (let ((name (coerce-name requested)))
+      (multiple-value-bind (keys foundp) (gethash name *preloaded-systems*)
+        (when foundp
+          (make-preloaded-system name keys)))))
+
+  (defun ensure-preloaded-system-registered (name)
+    "If there isn't a registered _defined_ system of given NAME,
+and a there is a registered _preloaded_ system of given NAME,
+then define and register said preloaded system."
+    (if-let (system (and (not (registered-system name)) (sysdef-preloaded-system-search name)))
+      (register-system system)))
+
+  (defun register-preloaded-system (system-name &rest keys &key (version t) &allow-other-keys)
+    "Register a system as being preloaded. If the system has not been loaded from the filesystem
+yet, or if its build information is later cleared with CLEAR-SYSTEM, a dummy system will be
+registered without backing filesystem information, based on KEYS (e.g. to provide a VERSION).
+If VERSION is the default T, and a system was already loaded, then its version will be preserved."
+    (let ((name (coerce-name system-name)))
+      (when (eql version t)
+        (if-let (system (registered-system name))
+          (setf (getf keys :version) (component-version system))))
+      (setf (gethash name *preloaded-systems*) keys)
+      (ensure-preloaded-system-registered system-name)))
+
+
+  ;;; Immutable systems: in the image and can't be reloaded from source.
+
+  (defvar *immutable-systems* nil
+    "A hash-set (equal hash-table mapping keys to T) of systems that are immutable,
+i.e. already loaded in memory and not to be refreshed from the filesystem.
+They will be treated specially by find-system, and passed as :force-not argument to make-plan.
+
+For instance, to can deliver an image with many systems precompiled, that *will not* check the
+filesystem for them every time a user loads an extension, what more risk a problematic upgrade
+ or catastrophic downgrade, before you dump an image, you may use:
+   (map () 'asdf:register-immutable-system (asdf:already-loaded-systems))
+
+Note that direct access to this variable from outside ASDF is not supported.
+Please call REGISTER-IMMUTABLE-SYSTEM to add new immutable systems, and
+contact maintainers if you need a stable API to do more than that.")
+
+  (defun sysdef-immutable-system-search (requested)
+    (let ((name (coerce-name requested)))
+      (when (and *immutable-systems* (gethash name *immutable-systems*))
+        (or (registered-system requested)
+            (error 'formatted-system-definition-error
+                   :format-control "Requested system ~A registered as an immutable-system, ~
+but not even registered as defined"
+                   :format-arguments (list name))))))
+
+  (defun register-immutable-system (system-name &rest keys)
+    "Register SYSTEM-NAME as preloaded and immutable.
+It will automatically be considered as passed to FORCE-NOT in a plan."
+    (let ((system-name (coerce-name system-name)))
+      (apply 'register-preloaded-system system-name keys)
+      (unless *immutable-systems*
+        (setf *immutable-systems* (list-to-hash-set nil)))
+      (setf (gethash system-name *immutable-systems*) t)))
+
+
+  ;;; Making systems undefined.
+
+  (defun clear-system (system)
+    "Clear the entry for a SYSTEM in the database of systems previously defined.
+However if the system was registered as PRELOADED (which it is if it is IMMUTABLE),
+then a new system with the same name will be defined and registered in its place
+from which build details will have been cleared.
+Note that this does NOT in any way cause any of the code of the system to be unloaded.
+Returns T if system was or is now undefined, NIL if a new preloaded system was redefined."
+    ;; There is no "unload" operation in Common Lisp, and
+    ;; a general such operation cannot be portably written,
+    ;; considering how much CL relies on side-effects to global data structures.
+    (let ((name (coerce-name system)))
+      (remhash name *registered-systems*)
+      (unset-asdf-cache-entry `(find-system ,name))
+      (not (ensure-preloaded-system-registered name))))
+
+  (defun clear-registered-systems ()
+    "Clear all currently registered defined systems.
+Preloaded systems (including immutable ones) will be reset, other systems will be de-registered."
+    (map () 'clear-system (registered-systems)))
+
+
+  ;;; Searching for system definitions
+
+  ;; For the sake of keeping things reasonably neat, we adopt a convention that
+  ;; only symbols are to be pushed to this list (rather than e.g. function objects),
+  ;; which makes upgrade easier. Also, the name of these symbols shall start with SYSDEF-
+  (defvar *system-definition-search-functions* '()
+    "A list that controls the ways that ASDF looks for system definitions.
+It contains symbols to be funcalled in order, with a requested system name as argument,
+until one returns a non-NIL result (if any), which must then be a fully initialized system object
+with that name.")
+
+  ;; Initialize and/or upgrade the *system-definition-search-functions*
+  ;; so it doesn't contain obsolete symbols, and does contain the current ones.
+  (defun cleanup-system-definition-search-functions ()
+    (setf *system-definition-search-functions*
+          (append
+           ;; Remove known-incompatible sysdef functions from old versions of asdf.
+           ;; Order matters, so we can't just use set-difference.
+           (let ((obsolete
+                  '(contrib-sysdef-search sysdef-find-asdf sysdef-preloaded-system-search)))
+             (remove-if #'(lambda (x) (member x obsolete)) *system-definition-search-functions*))
+           ;; Tuck our defaults at the end of the list if they were absent.
+           ;; This is imperfect, in case they were removed on purpose,
+           ;; but then it will be the responsibility of whoever removes these symmbols
+           ;; to upgrade asdf before he does such a thing rather than after.
+           (remove-if #'(lambda (x) (member x *system-definition-search-functions*))
+                      '(sysdef-central-registry-search
+                        sysdef-source-registry-search)))))
+  (cleanup-system-definition-search-functions)
+
+  ;; This (private) function does the search for a system definition using *s-d-s-f*;
+  ;; it is to be called by locate-system.
+  (defun search-for-system-definition (system)
+    ;; Search for valid definitions of the system available in the current session.
+    ;; Previous definitions as registered in *registered-systems* MUST NOT be considered;
+    ;; they will be reconciled by locate-system then find-system.
+    ;; There are two special treatments: first, specially search for objects being defined
+    ;; in the current session, to avoid definition races between several files;
+    ;; second, specially search for immutable systems, so they cannot be redefined.
+    ;; Finally, use the search functions specified in *system-definition-search-functions*.
+    (let ((name (coerce-name system)))
+      (flet ((try (f) (if-let ((x (funcall f name))) (return-from search-for-system-definition x))))
+        (try 'find-system-if-being-defined)
+        (try 'sysdef-immutable-system-search)
+        (map () #'try *system-definition-search-functions*))))
+
+
+  ;;; The legacy way of finding a system: the *central-registry*
+
+  ;; This variable contains a list of directories to be lazily searched for the requested asd
+  ;; by sysdef-central-registry-search.
+  (defvar *central-registry* nil
+    "A list of 'system directory designators' ASDF uses to find systems.
+
+A 'system directory designator' is a pathname or an expression
+which evaluates to a pathname. For example:
+
+    (setf asdf:*central-registry*
+          (list '*default-pathname-defaults*
+                #p\"/home/me/cl/systems/\"
+                #p\"/usr/share/common-lisp/systems/\"))
+
+This variable is for backward compatibility.
+Going forward, we recommend new users should be using the source-registry.")
+
+  ;; Function to look for an asd file of given NAME under a directory provided by DEFAULTS.
+  ;; Return the truename of that file if it is found and TRUENAME is true.
+  ;; Return NIL if the file is not found.
+  ;; On Windows, follow shortcuts to .asd files.
+  (defun probe-asd (name defaults &key truename)
+    (block nil
+      (when (directory-pathname-p defaults)
+        (if-let (file (probe-file*
+                       (ensure-absolute-pathname
+                        (parse-unix-namestring name :type "asd")
+                        #'(lambda () (ensure-absolute-pathname defaults 'get-pathname-defaults nil))
+                        nil)
+                       :truename truename))
+          (return file))
+        #-(or clisp genera) ; clisp doesn't need it, plain genera doesn't have read-sequence(!)
+        (os-cond
+         ((os-windows-p)
+          (when (physical-pathname-p defaults)
+            (let ((shortcut
+                    (make-pathname
+                     :defaults defaults :case :local
+                     :name (strcat name ".asd")
+                     :type "lnk")))
+              (when (probe-file* shortcut)
+                (ensure-pathname (parse-windows-shortcut shortcut) :namestring :native)))))))))
+
+  ;; Function to push onto *s-d-s-f* to use the *central-registry*
+  (defun sysdef-central-registry-search (system)
+    (let ((name (primary-system-name system))
+          (to-remove nil)
+          (to-replace nil))
+      (block nil
+        (unwind-protect
+             (dolist (dir *central-registry*)
+               (let ((defaults (eval dir))
+                     directorized)
+                 (when defaults
+                   (cond ((directory-pathname-p defaults)
+                          (let* ((file (probe-asd name defaults :truename *resolve-symlinks*)))
+                            (when file
+                              (return file))))
+                         (t
+                          (restart-case
+                              (let* ((*print-circle* nil)
+                                     (message
+                                       (format nil
+                                               (compatfmt "~@<While searching for system ~S: ~3i~_~S evaluated to ~S which is not an absolute directory.~@:>")
+                                               system dir defaults)))
+                                (error message))
+                            (remove-entry-from-registry ()
+                              :report "Remove entry from *central-registry* and continue"
+                              (push dir to-remove))
+                            (coerce-entry-to-directory ()
+                              :test (lambda (c) (declare (ignore c))
+                                      (and (not (directory-pathname-p defaults))
+                                           (directory-pathname-p
+                                            (setf directorized
+                                                  (ensure-directory-pathname defaults)))))
+                              :report (lambda (s)
+                                        (format s (compatfmt "~@<Coerce entry to ~a, replace ~a and continue.~@:>")
+                                                directorized dir))
+                              (push (cons dir directorized) to-replace))))))))
+          ;; cleanup
+          (dolist (dir to-remove)
+            (setf *central-registry* (remove dir *central-registry*)))
+          (dolist (pair to-replace)
+            (let* ((current (car pair))
+                   (new (cdr pair))
+                   (position (position current *central-registry*)))
+              (setf *central-registry*
+                    (append (subseq *central-registry* 0 position)
+                            (list new)
+                            (subseq *central-registry* (1+ position)))))))))))
+
+;;;; -------------------------------------------------------------------------
+;;;; Actions
+
+(uiop/package:define-package :asdf/action
+  (:nicknames :asdf-action)
+  (:recycle :asdf/action :asdf/plan :asdf)
+  (:use :uiop/common-lisp :uiop :asdf/upgrade :asdf/session :asdf/component :asdf/operation)
+  (:import-from :asdf/operation #:check-operation-constructor)
+  (:import-from :asdf/component #:%additional-input-files)
+  (:export
+   #:action #:define-convenience-action-methods
+   #:action-description #:format-action
+   #:downward-operation #:upward-operation #:sideway-operation #:selfward-operation
+   #:non-propagating-operation
+   #:component-depends-on
+   #:input-files #:output-files #:output-file #:operation-done-p
+   #:action-operation #:action-component #:make-action
+   #:component-operation-time #:mark-operation-done #:compute-action-stamp
+   #:perform #:perform-with-restarts #:retry #:accept
+   #:action-path #:find-action
+   #:operation-definition-warning #:operation-definition-error ;; condition
+   #:action-valid-p
+   #:circular-dependency #:circular-dependency-actions
+   #:call-while-visiting-action #:while-visiting-action
+   #:additional-input-files))
+(in-package :asdf/action)
+
+(eval-when (#-lispworks :compile-toplevel :load-toplevel :execute) ;; LispWorks issues spurious warning
+
+  (deftype action ()
+    "A pair of operation and component uniquely identifies a node in the dependency graph
+of steps to be performed while building a system."
+    '(cons operation component))
+
+  (deftype operation-designator ()
+    "An operation designates itself. NIL designates a context-dependent current operation,
+and a class-name or class designates the canonical instance of the designated class."
+    '(or operation null symbol class)))
+
+;;; these are pseudo accessors -- let us abstract away the CONS cell representation of plan
+;;; actions.
+(with-upgradability ()
+  (defun make-action (operation component)
+    (cons operation component))
+  (defun action-operation (action)
+    (car action))
+  (defun action-component (action)
+    (cdr action)))
+
+;;;; Reified representation for storage or debugging. Note: an action is identified by its class.
+(with-upgradability ()
+  (defun action-path (action)
+    "A readable data structure that identifies the action."
+    (when action
+      (let ((o (action-operation action))
+            (c (action-component action)))
+        (cons (type-of o) (component-find-path c)))))
+  (defun find-action (path)
+    "Reconstitute an action from its action-path"
+    (destructuring-bind (o . c) path (make-action (make-operation o) (find-component () c)))))
+
+;;;; Convenience methods
+(with-upgradability ()
+  ;; A macro that defines convenience methods for a generic function (gf) that
+  ;; dispatches on operation and component.  The convenience methods allow users
+  ;; to call the gf with operation and/or component designators, that the
+  ;; methods will resolve into actual operation and component objects, so that
+  ;; the users can interact using readable designators, but developers only have
+  ;; to write methods that handle operation and component objects.
+  ;; FUNCTION is the generic function name
+  ;; FORMALS is its list of arguments, which must include OPERATION and COMPONENT.
+  ;; IF-NO-OPERATION is a form (defaults to NIL) describing what to do if no operation is found.
+  ;; IF-NO-COMPONENT is a form (defaults to NIL) describing what to do if no component is found.
+  (defmacro define-convenience-action-methods
+      (function formals &key if-no-operation if-no-component)
+    (let* ((rest (gensym "REST"))
+           (found (gensym "FOUND"))
+           (keyp (equal (last formals) '(&key)))
+           (formals-no-key (if keyp (butlast formals) formals))
+           (len (length formals-no-key))
+           (operation 'operation)
+           (component 'component)
+           (opix (position operation formals))
+           (coix (position component formals))
+           (prefix (subseq formals 0 opix))
+           (suffix (subseq formals (1+ coix) len))
+           (more-args (when keyp `(&rest ,rest &key &allow-other-keys))))
+      (assert (and (integerp opix) (integerp coix) (= coix (1+ opix))))
+      (flet ((next-method (o c)
+               (if keyp
+                   `(apply ',function ,@prefix ,o ,c ,@suffix ,rest)
+                   `(,function ,@prefix ,o ,c ,@suffix))))
+        `(progn
+           (defmethod ,function (,@prefix (,operation string) ,component ,@suffix ,@more-args)
+             (declare (notinline ,function))
+             (let ((,component (find-component () ,component))) ;; do it first, for defsystem-depends-on
+               ,(next-method `(safe-read-from-string ,operation :package :asdf/interface) component)))
+           (defmethod ,function (,@prefix (,operation symbol) ,component ,@suffix ,@more-args)
+             (declare (notinline ,function))
+             (if ,operation
+                 ,(next-method
+                   `(make-operation ,operation)
+                   `(or (find-component () ,component) ,if-no-component))
+                 ,if-no-operation))
+           (defmethod ,function (,@prefix (,operation operation) ,component ,@suffix ,@more-args)
+             (declare (notinline ,function))
+             (if (typep ,component 'component)
+                 (error "No defined method for ~S on ~/asdf-action:format-action/"
+                        ',function (make-action ,operation ,component))
+                 (if-let (,found (find-component () ,component))
+                    ,(next-method operation found)
+                    ,if-no-component))))))))
+
+
+;;;; Self-description
+(with-upgradability ()
+  (defgeneric action-description (operation component)
+    (:documentation "returns a phrase that describes performing this operation
+on this component, e.g. \"loading /a/b/c\".
+You can put together sentences using this phrase."))
+  (defmethod action-description (operation component)
+    (format nil (compatfmt "~@<~A on ~A~@:>")
+            operation component))
+
+  (defun format-action (stream action &optional colon-p at-sign-p)
+    "FORMAT helper to display an action's action-description.
+Use it in FORMAT control strings as ~/asdf-action:format-action/"
+    (assert (null colon-p)) (assert (null at-sign-p))
+    (destructuring-bind (operation . component) action
+      (princ (action-description operation component) stream))))
+
+
+;;;; Detection of circular dependencies
+(with-upgradability ()
+  (defun action-valid-p (operation component)
+    "Is this action valid to include amongst dependencies?"
+    ;; If either the operation or component was resolved to nil, the action is invalid.
+    ;; :if-feature will invalidate actions on components for which the features don't apply.
+    (and operation component
+         (if-let (it (component-if-feature component)) (featurep it) t)))
+
+  (define-condition circular-dependency (system-definition-error)
+    ((actions :initarg :actions :reader circular-dependency-actions))
+    (:report (lambda (c s)
+               (format s (compatfmt "~@<Circular dependency of ~s on: ~3i~_~S~@:>")
+                       (first (circular-dependency-actions c))
+                       (circular-dependency-actions c)))))
+
+  (defun call-while-visiting-action (operation component fun)
+    "Detect circular dependencies"
+    (with-asdf-session ()
+      (with-accessors ((action-set visiting-action-set)
+                       (action-list visiting-action-list)) *asdf-session*
+        (let ((action (cons operation component)))
+          (when (gethash action action-set)
+            (error 'circular-dependency :actions
+                   (member action (reverse action-list) :test 'equal)))
+          (setf (gethash action action-set) t)
+          (push action action-list)
+          (unwind-protect
+               (funcall fun)
+            (pop action-list)
+            (setf (gethash action action-set) nil))))))
+
+  ;; Syntactic sugar for call-while-visiting-action
+  (defmacro while-visiting-action ((o c) &body body)
+    `(call-while-visiting-action ,o ,c #'(lambda () ,@body))))
+
+
+;;;; Dependencies
+(with-upgradability ()
+  (defgeneric component-depends-on (operation component) ;; ASDF4: rename to component-dependencies
+    (:documentation
+     "Returns a list of dependencies needed by the component to perform
+    the operation.  A dependency has one of the following forms:
+
+      (<operation> <component>*), where <operation> is an operation designator
+        with respect to FIND-OPERATION in the context of the OPERATION argument,
+        and each <component> is a component designator with respect to
+        FIND-COMPONENT in the context of the COMPONENT argument,
+        and means that the component depends on
+        <operation> having been performed on each <component>;
+
+        [Note: an <operation> is an operation designator -- it can be either an
+        operation name or an operation object.  Similarly, a <component> may be
+        a component name or a component object.  Also note that, the degenerate
+        case of (<operation>) is a no-op.]
+
+    Methods specialized on subclasses of existing component types
+    should usually append the results of CALL-NEXT-METHOD to the list."))
+  (define-convenience-action-methods component-depends-on (operation component))
+
+  (defmethod component-depends-on :around ((o operation) (c component))
+    (do-asdf-cache `(component-depends-on ,o ,c)
+      (call-next-method))))
+
+
+;;;; upward-operation, downward-operation, sideway-operation, selfward-operation
+;; These together handle actions that propagate along the component hierarchy or operation universe.
+(with-upgradability ()
+  (defclass downward-operation (operation)
+    ((downward-operation
+      :initform nil :reader downward-operation
+      :type operation-designator :allocation :class))
+    (:documentation "A DOWNWARD-OPERATION's dependencies propagate down the component hierarchy.
+I.e., if O is a DOWNWARD-OPERATION and its DOWNWARD-OPERATION slot designates operation D, then
+the action (O . M) of O on module M will depends on each of (D . C) for each child C of module M.
+The default value for slot DOWNWARD-OPERATION is NIL, which designates the operation O itself.
+E.g. in order for a MODULE to be loaded with LOAD-OP (resp. compiled with COMPILE-OP), all the
+children of the MODULE must have been loaded with LOAD-OP (resp. compiled with COMPILE-OP."))
+  (defun downward-operation-depends-on (o c)
+    `((,(or (downward-operation o) o) ,@(component-children c))))
+  (defmethod component-depends-on ((o downward-operation) (c parent-component))
+    `(,@(downward-operation-depends-on o c) ,@(call-next-method)))
+
+  (defclass upward-operation (operation)
+    ((upward-operation
+      :initform nil :reader upward-operation
+      :type operation-designator :allocation :class))
+    (:documentation "An UPWARD-OPERATION has dependencies that propagate up the component hierarchy.
+I.e., if O is an instance of UPWARD-OPERATION, and its UPWARD-OPERATION slot designates operation U,
+then the action (O . C) of O on a component C that has the parent P will depends on (U . P).
+The default value for slot UPWARD-OPERATION is NIL, which designates the operation O itself.
+E.g. in order for a COMPONENT to be prepared for loading or compiling with PREPARE-OP, its PARENT
+must first be prepared for loading or compiling with PREPARE-OP."))
+  ;; For backward-compatibility reasons, a system inherits from module and is a child-component
+  ;; so we must guard against this case. ASDF4: remove that.
+  (defun upward-operation-depends-on (o c)
+    (if-let (p (component-parent c)) `((,(or (upward-operation o) o) ,p))))
+  (defmethod component-depends-on ((o upward-operation) (c child-component))
+    `(,@(upward-operation-depends-on o c) ,@(call-next-method)))
+
+  (defclass sideway-operation (operation)
+    ((sideway-operation
+      :initform nil :reader sideway-operation
+      :type operation-designator :allocation :class))
+    (:documentation "A SIDEWAY-OPERATION has dependencies that propagate \"sideway\" to siblings
+that a component depends on. I.e. if O is a SIDEWAY-OPERATION, and its SIDEWAY-OPERATION slot
+designates operation S (where NIL designates O itself), then the action (O . C) of O on component C
+depends on each of (S . D) where D is a declared dependency of C.
+E.g. in order for a COMPONENT to be prepared for loading or compiling with PREPARE-OP,
+each of its declared dependencies must first be loaded as by LOAD-OP."))
+  (defun sideway-operation-depends-on (o c)
+    `((,(or (sideway-operation o) o) ,@(component-sideway-dependencies c))))
+  (defmethod component-depends-on ((o sideway-operation) (c component))
+    `(,@(sideway-operation-depends-on o c) ,@(call-next-method)))
+
+  (defclass selfward-operation (operation)
+    ((selfward-operation
+      ;; NB: no :initform -- if an operation depends on others, it must explicitly specify which
+      :type (or operation-designator list) :reader selfward-operation :allocation :class))
+    (:documentation "A SELFWARD-OPERATION depends on another operation on the same component.
+I.e., if O is a SELFWARD-OPERATION, and its SELFWARD-OPERATION designates a list of operations L,
+then the action (O . C) of O on component C depends on each (S . C) for S in L.
+E.g. before a component may be loaded by LOAD-OP, it must have been compiled by COMPILE-OP.
+A operation-designator designates a singleton list of the designated operation;
+a list of operation-designators designates the list of designated operations;
+NIL is not a valid operation designator in that context.  Note that any dependency
+ordering between the operations in a list of SELFWARD-OPERATION should be specified separately
+in the respective operation's COMPONENT-DEPENDS-ON methods so that they be scheduled properly."))
+  (defun selfward-operation-depends-on (o c)
+    (loop :for op :in (ensure-list (selfward-operation o)) :collect `(,op ,c)))
+  (defmethod component-depends-on ((o selfward-operation) (c component))
+    `(,@(selfward-operation-depends-on o c) ,@(call-next-method)))
+
+  (defclass non-propagating-operation (operation)
+    ()
+    (:documentation "A NON-PROPAGATING-OPERATION is an operation that propagates
+no dependencies whatsoever.  It is supplied in order that the programmer be able
+to specify that s/he is intentionally specifying an operation which invokes no
+dependencies.")))
+
+
+;;;---------------------------------------------------------------------------
+;;; Help programmers catch obsolete OPERATION subclasses
+;;;---------------------------------------------------------------------------
+(with-upgradability ()
+  (define-condition operation-definition-warning (simple-warning)
+    ()
+    (:documentation "Warning condition related to definition of obsolete OPERATION objects."))
+
+  (define-condition operation-definition-error (simple-error)
+    ()
+    (:documentation "Error condition related to definition of incorrect OPERATION objects."))
+
+  (defmethod initialize-instance :before ((o operation) &key)
+    (check-operation-constructor)
+    (unless (typep o '(or downward-operation upward-operation sideway-operation
+                          selfward-operation non-propagating-operation))
+      (warn 'operation-definition-warning
+            :format-control
+            "No dependency propagating scheme specified for operation class ~S.
+The class needs to be updated for ASDF 3.1 and specify appropriate propagation mixins."
+            :format-arguments (list (type-of o)))))
+
+  (defmethod initialize-instance :before ((o non-propagating-operation) &key)
+    (when (typep o '(or downward-operation upward-operation sideway-operation selfward-operation))
+      (error 'operation-definition-error
+             :format-control
+             "Inconsistent class: ~S
+  NON-PROPAGATING-OPERATION is incompatible with propagating operation classes as superclasses."
+             :format-arguments
+             (list (type-of o)))))
+
+  (defun backward-compatible-depends-on (o c)
+    "DEPRECATED: all subclasses of OPERATION used in ASDF should inherit from one of
+ DOWNWARD-OPERATION UPWARD-OPERATION SIDEWAY-OPERATION SELFWARD-OPERATION NON-PROPAGATING-OPERATION.
+ The function BACKWARD-COMPATIBLE-DEPENDS-ON temporarily provides ASDF2 behaviour for those that
+ don't. In the future this functionality will be removed, and the default will be no propagation."
+    (uiop/version::notify-deprecated-function
+     (version-deprecation *asdf-version* :style-warning "3.2")
+     `(backward-compatible-depends-on :for-operation ,o))
+    `(,@(sideway-operation-depends-on o c)
+      ,@(when (typep c 'parent-component) (downward-operation-depends-on o c))))
+
+  (defmethod component-depends-on ((o operation) (c component))
+    `(;; Normal behavior, to allow user-specified in-order-to dependencies
+      ,@(cdr (assoc (type-of o) (component-in-order-to c)))
+        ;; For backward-compatibility with ASDF2, any operation that doesn't specify propagation
+        ;; or non-propagation through an appropriate mixin will be downward and sideway.
+        ,@(unless (typep o '(or downward-operation upward-operation sideway-operation
+                             selfward-operation non-propagating-operation))
+            (backward-compatible-depends-on o c))))
+
+  (defmethod downward-operation ((o operation)) nil)
+  (defmethod sideway-operation ((o operation)) nil))
+
+
+;;;---------------------------------------------------------------------------
+;;; End of OPERATION class checking
+;;;---------------------------------------------------------------------------
+
+
+;;;; Inputs, Outputs, and invisible dependencies
+(with-upgradability ()
+  (defgeneric output-files (operation component)
+    (:documentation "Methods for this function return two values: a list of output files
+corresponding to this action, and a boolean indicating if they have already been subjected
+to relevant output translations and should not be further translated.
+
+Methods on PERFORM *must* call this function to determine where their outputs are to be located.
+They may rely on the order of the files to discriminate between outputs.
+"))
+  (defgeneric input-files (operation component)
+    (:documentation "A list of input files corresponding to this action.
+
+Methods on PERFORM *must* call this function to determine where their inputs are located.
+They may rely on the order of the files to discriminate between inputs.
+"))
+  (defgeneric operation-done-p (operation component)
+    (:documentation "Returns a boolean which is NIL if the action must be performed (again)."))
+  (define-convenience-action-methods output-files (operation component))
+  (define-convenience-action-methods input-files (operation component))
+  (define-convenience-action-methods operation-done-p (operation component))
+
+  (defmethod operation-done-p ((o operation) (c component))
+    t)
+
+  ;; Translate output files, unless asked not to. Memoize the result.
+  (defmethod output-files :around ((operation t) (component t))
+    (do-asdf-cache `(output-files ,operation ,component)
+      (values
+       (multiple-value-bind (pathnames fixedp) (call-next-method)
+         ;; 1- Make sure we have absolute pathnames
+         (let* ((directory (pathname-directory-pathname
+                            (component-pathname (find-component () component))))
+                (absolute-pathnames
+                  (loop
+                    :for pathname :in pathnames
+                    :collect (ensure-absolute-pathname pathname directory))))
+           ;; 2- Translate those pathnames as required
+           (if fixedp
+               absolute-pathnames
+               (mapcar *output-translation-function* absolute-pathnames))))
+       t)))
+  (defmethod output-files ((o operation) (c component))
+    nil)
+  (defun output-file (operation component)
+    "The unique output file of performing OPERATION on COMPONENT"
+    (let ((files (output-files operation component)))
+      (assert (length=n-p files 1))
+      (first files)))
+
+  (defgeneric additional-input-files (operation component)
+    (:documentation "Additional input files for the operation on this
+    component.  These are files that are inferred, rather than
+    explicitly specified, and these are typically NOT files that
+    undergo operations directly.  Instead, they are files that it is
+    important for ASDF to know about in order to compute operation times,etc."))
+  (define-convenience-action-methods additional-input-files (operation component))
+  (defmethod additional-input-files ((op operation) (comp component))
+      (cdr (assoc op (%additional-input-files comp))))
+
+  ;; Memoize input files.
+  (defmethod input-files :around (operation component)
+    (do-asdf-cache `(input-files ,operation ,component)
+      ;; get the additional input files, if any
+      (append (call-next-method)
+              ;; must come after the first, for other code that
+              ;; assumes the first will be the "key" file
+              (additional-input-files operation component))))
+
+  ;; By default an action has no input-files.
+  (defmethod input-files ((o operation) (c component))
+    nil)
+
+  ;; An action with a selfward-operation by default gets its input-files from the output-files of
+  ;; the actions using selfward-operations it depends on (and the same component),
+  ;; or if there are none, on the component-pathname of the component if it's a file
+  ;; -- and then on the results of the next-method.
+  (defmethod input-files ((o selfward-operation) (c component))
+    `(,@(or (loop :for dep-o :in (ensure-list (selfward-operation o))
+                  :append (or (output-files dep-o c) (input-files dep-o c)))
+            (if-let ((pathname (component-pathname c)))
+              (and (file-pathname-p pathname) (list pathname))))
+      ,@(call-next-method))))
+
+
+;;;; Done performing
+(with-upgradability ()
+  ;; ASDF4: hide it behind plan-action-stamp
+  (defgeneric component-operation-time (operation component)
+    (:documentation "Return the timestamp for when an action was last performed"))
+  (defgeneric (setf component-operation-time) (time operation component)
+    (:documentation "Update the timestamp for when an action was last performed"))
+  (define-convenience-action-methods component-operation-time (operation component))
+
+  ;; ASDF4: hide it behind (setf plan-action-stamp)
+  (defgeneric mark-operation-done (operation component)
+    (:documentation "Mark a action as having been just done.
+
+Updates the action's COMPONENT-OPERATION-TIME to match the COMPUTE-ACTION-STAMP
+using the JUST-DONE flag."))
+  (defgeneric compute-action-stamp (plan- operation component &key just-done)
+    ;; NB: using plan- rather than plan above allows clisp to upgrade from 2.26(!)
+    (:documentation "Has this action been successfully done already,
+and at what known timestamp has it been done at or will it be done at?
+* PLAN is a plan object modelling future effects of actions,
+  or NIL to denote what actually happened.
+* OPERATION and COMPONENT denote the action.
+Takes keyword JUST-DONE:
+* JUST-DONE is a boolean that is true if the action was just successfully performed,
+  at which point we want compute the actual stamp and warn if files are missing;
+  otherwise we are making plans, anticipating the effects of the action.
+Returns two values:
+* a STAMP saying when it was done or will be done,
+  or T if the action involves files that need to be recomputed.
+* a boolean DONE-P that indicates whether the action has actually been done,
+  and both its output-files and its in-image side-effects are up to date."))
+
+  (defmethod component-operation-time ((o operation) (c component))
+    (gethash o (component-operation-times c)))
+
+  (defmethod (setf component-operation-time) (stamp (o operation) (c component))
+    (assert stamp () "invalid null stamp for ~A" (action-description o c))
+    (setf (gethash o (component-operation-times c)) stamp))
+
+  (defmethod mark-operation-done ((o operation) (c component))
+    (let ((stamp (compute-action-stamp nil o c :just-done t)))
+      (assert stamp () "Failed to compute a stamp for completed action ~A" (action-description o c))1
+      (setf (component-operation-time o c) stamp))))
+
+
+;;;; Perform
+(with-upgradability ()
+  (defgeneric perform (operation component)
+    (:documentation "PERFORM an action, consuming its input-files and building its output-files"))
+  (define-convenience-action-methods perform (operation component))
+
+  (defmethod perform :around ((o operation) (c component))
+    (while-visiting-action (o c) (call-next-method)))
+  (defmethod perform :before ((o operation) (c component))
+    (ensure-all-directories-exist (output-files o c)))
+  (defmethod perform :after ((o operation) (c component))
+    (mark-operation-done o c))
+  (defmethod perform ((o operation) (c parent-component))
+    nil)
+  (defmethod perform ((o operation) (c source-file))
+    ;; For backward compatibility, don't error on operations that don't specify propagation.
+    (when (typep o '(or downward-operation upward-operation sideway-operation
+                     selfward-operation non-propagating-operation))
+      (sysdef-error
+       (compatfmt "~@<Required method ~S not implemented for ~/asdf-action:format-action/~@:>")
+       'perform (make-action o c))))
+
+  ;; The restarts of the perform-with-restarts variant matter in an interactive context.
+  ;; The retry strategies of p-w-r itself, and/or the background workers of a multiprocess build
+  ;; may call perform directly rather than call p-w-r.
+  (defgeneric perform-with-restarts (operation component)
+    (:documentation "PERFORM an action in a context where suitable restarts are in place."))
+  (defmethod perform-with-restarts (operation component)
+    (perform operation component))
+  (defmethod perform-with-restarts :around (operation component)
+    (loop
+      (restart-case
+          (return (call-next-method))
+        (retry ()
+          :report
+          (lambda (s)
+            (format s (compatfmt "~@<Retry ~A.~@:>")
+                    (action-description operation component))))
+        (accept ()
+          :report
+          (lambda (s)
+            (format s (compatfmt "~@<Continue, treating ~A as having been successful.~@:>")
+                    (action-description operation component)))
+          (mark-operation-done operation component)
+          (return))))))
+;;;; -------------------------------------------------------------------------
+;;;; Actions to build Common Lisp software
+
+(uiop/package:define-package :asdf/lisp-action
+  (:recycle :asdf/lisp-action :asdf)
+  (:use :uiop/common-lisp :uiop :asdf/upgrade :asdf/session
+   :asdf/component :asdf/system :asdf/operation :asdf/action)
+  (:export
+   #:try-recompiling
+   #:cl-source-file #:cl-source-file.cl #:cl-source-file.lsp
+   #:basic-load-op #:basic-compile-op
+   #:load-op #:prepare-op #:compile-op #:test-op #:load-source-op #:prepare-source-op
+   #:call-with-around-compile-hook
+   #:perform-lisp-compilation #:perform-lisp-load-fasl #:perform-lisp-load-source
+   #:lisp-compilation-output-files))
+(in-package :asdf/lisp-action)
+
+
+;;;; Component classes
+(with-upgradability ()
+  (defclass cl-source-file (source-file)
+    ((type :initform "lisp"))
+    (:documentation "Component class for a Common Lisp source file (using type \"lisp\")"))
+  (defclass cl-source-file.cl (cl-source-file)
+    ((type :initform "cl"))
+    (:documentation "Component class for a Common Lisp source file using type \"cl\""))
+  (defclass cl-source-file.lsp (cl-source-file)
+    ((type :initform "lsp"))
+    (:documentation "Component class for a Common Lisp source file using type \"lsp\"")))
+
+
+;;;; Operation classes
+(with-upgradability ()
+  (defclass basic-load-op (operation) ()
+    (:documentation "Base class for operations that apply the load-time effects of a file"))
+  (defclass basic-compile-op (operation) ()
+    (:documentation "Base class for operations that apply the compile-time effects of a file")))
+
+
+;;; Our default operations: loading into the current lisp image
+(with-upgradability ()
+  (defclass prepare-op (upward-operation sideway-operation)
+    ((sideway-operation :initform 'load-op :allocation :class))
+    (:documentation "Load the dependencies for the COMPILE-OP or LOAD-OP of a given COMPONENT."))
+  (defclass load-op (basic-load-op downward-operation selfward-operation)
+    ;; NB: even though compile-op depends on prepare-op it is not needed-in-image-p,
+    ;; so we need to directly depend on prepare-op for its side-effects in the current image.
+    ((selfward-operation :initform '(prepare-op compile-op) :allocation :class))
+    (:documentation "Operation for loading the compiled FASL for a Lisp file"))
+  (defclass compile-op (basic-compile-op downward-operation selfward-operation)
+    ((selfward-operation :initform 'prepare-op :allocation :class))
+    (:documentation "Operation for compiling a Lisp file to a FASL"))
+
+
+  (defclass prepare-source-op (upward-operation sideway-operation)
+    ((sideway-operation :initform 'load-source-op :allocation :class))
+    (:documentation "Operation for loading the dependencies of a Lisp file as source."))
+  (defclass load-source-op (basic-load-op downward-operation selfward-operation)
+    ((selfward-operation :initform 'prepare-source-op :allocation :class))
+    (:documentation "Operation for loading a Lisp file as source."))
+
+  (defclass test-op (selfward-operation)
+    ((selfward-operation :initform 'load-op :allocation :class))
+    (:documentation "Operation for running the tests for system.
+If the tests fail, an error will be signaled.")))
+
+
+;;;; Methods for prepare-op, compile-op and load-op
+
+;;; prepare-op
+(with-upgradability ()
+  (defmethod action-description ((o prepare-op) (c component))
+    (format nil (compatfmt "~@<loading dependencies of ~3i~_~A~@:>") c))
+  (defmethod perform ((o prepare-op) (c component))
+    nil)
+  (defmethod input-files ((o prepare-op) (s system))
+    (if-let (it (system-source-file s)) (list it))))
+
+;;; compile-op
+(with-upgradability ()
+  (defmethod action-description ((o compile-op) (c component))
+    (format nil (compatfmt "~@<compiling ~3i~_~A~@:>") c))
+  (defmethod action-description ((o compile-op) (c parent-component))
+    (format nil (compatfmt "~@<completing compilation for ~3i~_~A~@:>") c))
+  (defgeneric call-with-around-compile-hook (component thunk)
+    (:documentation "A method to be called around the PERFORM'ing of actions that apply the
+compile-time side-effects of file (i.e., COMPILE-OP or LOAD-SOURCE-OP). This method can be used
+to setup readtables and other variables that control reading, macroexpanding, and compiling, etc.
+Note that it will NOT be called around the performing of LOAD-OP."))
+  (defmethod call-with-around-compile-hook ((c component) function)
+    (call-around-hook (around-compile-hook c) function))
+  (defun perform-lisp-compilation (o c)
+    "Perform the compilation of the Lisp file associated to the specified action (O . C)."
+    (let (;; Before 2.26.53, that was unfortunately component-pathname. Now,
+          ;; we consult input-files, the first of which should be the one to compile-file
+          (input-file (first (input-files o c)))
+          ;; On some implementations, there are more than one output-file,
+          ;; but the first one should always be the primary fasl that gets loaded.
+          (outputs (output-files o c)))
+      (multiple-value-bind (output warnings-p failure-p)
+          (destructuring-bind
+              (output-file
+               &optional
+                 #+(or clasp ecl mkcl) object-file
+                 #+clisp lib-file
+                 warnings-file &rest rest) outputs
+            ;; Allow for extra outputs that are not of type warnings-file
+            ;; The way we do it is kludgy. In ASDF4, output-files shall not be positional.
+            (declare (ignore rest))
+            (when warnings-file
+              (unless (equal (pathname-type warnings-file) (warnings-file-type))
+                (setf warnings-file nil)))
+            (call-with-around-compile-hook
+             c #'(lambda (&rest flags)
+                   (apply 'compile-file* input-file
+                          :output-file output-file
+                          :external-format (component-external-format c)
+                          :warnings-file warnings-file
+                          (append
+                           #+clisp (list :lib-file lib-file)
+                           #+(or clasp ecl mkcl) (list :object-file object-file)
+                           flags)))))
+        (check-lisp-compile-results output warnings-p failure-p
+                                    "~/asdf-action::format-action/" (list (cons o c))))))
+  (defun report-file-p (f)
+    "Is F a build report file containing, e.g., warnings to check?"
+    (equalp (pathname-type f) "build-report"))
+  (defun perform-lisp-warnings-check (o c)
+    "Check the warnings associated with the dependencies of an action."
+    (let* ((expected-warnings-files (remove-if-not #'warnings-file-p (input-files o c)))
+           (actual-warnings-files (loop :for w :in expected-warnings-files
+                                        :when (get-file-stamp w)
+                                          :collect w
+                                        :else :do (warn "Missing warnings file ~S while ~A"
+                                                        w (action-description o c)))))
+      (check-deferred-warnings actual-warnings-files)
+      (let* ((output (output-files o c))
+             (report (find-if #'report-file-p output)))
+        (when report
+          (with-open-file (s report :direction :output :if-exists :supersede)
+            (format s ":success~%"))))))
+  (defmethod perform ((o compile-op) (c cl-source-file))
+    (perform-lisp-compilation o c))
+  (defun lisp-compilation-output-files (o c)
+    "Compute the output-files for compiling the Lisp file for the specified action (O . C),
+an OPERATION and a COMPONENT."
+    (let* ((i (first (input-files o c)))
+           (f (compile-file-pathname
+               i #+clasp :output-type #+ecl :type #+(or clasp ecl) :fasl
+               #+mkcl :fasl-p #+mkcl t)))
+      `(,f ;; the fasl is the primary output, in first position
+        #+clasp
+        ,@(unless nil ;; was (use-ecl-byte-compiler-p)
+            `(,(compile-file-pathname i :output-type :object)))
+        #+clisp
+        ,@`(,(make-pathname :type "lib" :defaults f))
+        #+ecl
+        ,@(unless (use-ecl-byte-compiler-p)
+            `(,(compile-file-pathname i :type :object)))
+        #+mkcl
+        ,(compile-file-pathname i :fasl-p nil) ;; object file
+        ,@(when (and *warnings-file-type* (not (builtin-system-p (component-system c))))
+            `(,(make-pathname :type *warnings-file-type* :defaults f))))))
+  (defmethod output-files ((o compile-op) (c cl-source-file))
+    (lisp-compilation-output-files o c))
+  (defmethod perform ((o compile-op) (c static-file))
+    nil)
+
+  ;; Performing compile-op on a system will check the deferred warnings for the system
+  (defmethod perform ((o compile-op) (c system))
+    (when (and *warnings-file-type* (not (builtin-system-p c)))
+      (perform-lisp-warnings-check o c)))
+  (defmethod input-files ((o compile-op) (c system))
+    (when (and *warnings-file-type* (not (builtin-system-p c)))
+      ;; The most correct way to do it would be to use:
+      ;; (collect-dependencies o c :other-systems nil :keep-operation 'compile-op :keep-component 'cl-source-file)
+      ;; but it's expensive and we don't care too much about file order or ASDF extensions.
+      (loop :for sub :in (sub-components c :type 'cl-source-file)
+            :nconc (remove-if-not 'warnings-file-p (output-files o sub)))))
+  (defmethod output-files ((o compile-op) (c system))
+    (when (and *warnings-file-type* (not (builtin-system-p c)))
+      (if-let ((pathname (component-pathname c)))
+        (list (subpathname pathname (coerce-filename c) :type "build-report"))))))
+
+;;; load-op
+(with-upgradability ()
+  (defmethod action-description ((o load-op) (c cl-source-file))
+    (format nil (compatfmt "~@<loading FASL for ~3i~_~A~@:>") c))
+  (defmethod action-description ((o load-op) (c parent-component))
+    (format nil (compatfmt "~@<completing load for ~3i~_~A~@:>") c))
+  (defmethod action-description ((o load-op) (c component))
+    (format nil (compatfmt "~@<loading ~3i~_~A~@:>") c))
+  (defmethod perform-with-restarts ((o load-op) (c cl-source-file))
+    (loop
+      (restart-case
+          (return (call-next-method))
+        (try-recompiling ()
+          :report (lambda (s)
+                    (format s "Recompile ~a and try loading it again"
+                            (component-name c)))
+          (perform (find-operation o 'compile-op) c)))))
+  (defun perform-lisp-load-fasl (o c)
+    "Perform the loading of a FASL associated to specified action (O . C),
+an OPERATION and a COMPONENT."
+    (if-let (fasl (first (input-files o c)))
+      (load* fasl)))
+  (defmethod perform ((o load-op) (c cl-source-file))
+    (perform-lisp-load-fasl o c))
+  (defmethod perform ((o load-op) (c static-file))
+    nil))
+
+
+;;;; prepare-source-op, load-source-op
+
+;;; prepare-source-op
+(with-upgradability ()
+  (defmethod action-description ((o prepare-source-op) (c component))
+    (format nil (compatfmt "~@<loading source for dependencies of ~3i~_~A~@:>") c))
+  (defmethod input-files ((o prepare-source-op) (s system))
+    (if-let (it (system-source-file s)) (list it)))
+  (defmethod perform ((o prepare-source-op) (c component))
+    nil))
+
+;;; load-source-op
+(with-upgradability ()
+  (defmethod action-description ((o load-source-op) (c component))
+    (format nil (compatfmt "~@<Loading source of ~3i~_~A~@:>") c))
+  (defmethod action-description ((o load-source-op) (c parent-component))
+    (format nil (compatfmt "~@<Loaded source of ~3i~_~A~@:>") c))
+  (defun perform-lisp-load-source (o c)
+    "Perform the loading of a Lisp file as associated to specified action (O . C)"
+    (call-with-around-compile-hook
+     c #'(lambda ()
+           (load* (first (input-files o c))
+                  :external-format (component-external-format c)))))
+
+  (defmethod perform ((o load-source-op) (c cl-source-file))
+    (perform-lisp-load-source o c))
+  (defmethod perform ((o load-source-op) (c static-file))
+    nil))
+
+
+;;;; test-op
+(with-upgradability ()
+  (defmethod perform ((o test-op) (c component))
+    nil)
+  (defmethod operation-done-p ((o test-op) (c system))
+    "Testing a system is _never_ done."
+    nil))
+;;;; -------------------------------------------------------------------------
+;;;; Finding components
+
+(uiop/package:define-package :asdf/find-component
+  (:recycle :asdf/find-component :asdf/find-system :asdf)
+  (:use :uiop/common-lisp :uiop :asdf/upgrade :asdf/session
+   :asdf/component :asdf/system :asdf/system-registry)
+  (:export
+   #:find-component
+   #:resolve-dependency-name #:resolve-dependency-spec
+   #:resolve-dependency-combination
+   ;; Conditions
+   #:missing-component #:missing-requires #:missing-parent #:missing-component-of-version #:retry
+   #:missing-dependency #:missing-dependency-of-version
+   #:missing-requires #:missing-parent
+   #:missing-required-by #:missing-version))
+(in-package :asdf/find-component)
+
+;;;; Missing component conditions
+
+(with-upgradability ()
+  (define-condition missing-component (system-definition-error)
+    ((requires :initform "(unnamed)" :reader missing-requires :initarg :requires)
+     (parent :initform nil :reader missing-parent :initarg :parent)))
+
+  (define-condition missing-component-of-version (missing-component)
+    ((version :initform nil :reader missing-version :initarg :version)))
+
+  (define-condition missing-dependency (missing-component)
+    ((required-by :initarg :required-by :reader missing-required-by)))
+
+  (defmethod print-object ((c missing-dependency) s)
+    (format s (compatfmt "~@<~A, required by ~A~@:>")
+            (call-next-method c nil) (missing-required-by c)))
+
+  (define-condition missing-dependency-of-version (missing-dependency
+                                                   missing-component-of-version)
+    ())
+
+  (defmethod print-object ((c missing-component) s)
+    (format s (compatfmt "~@<Component ~S not found~@[ in ~A~]~@:>")
+            (missing-requires c)
+            (when (missing-parent c)
+              (coerce-name (missing-parent c)))))
+
+  (defmethod print-object ((c missing-component-of-version) s)
+    (format s (compatfmt "~@<Component ~S does not match version ~A~@[ in ~A~]~@:>")
+            (missing-requires c)
+            (missing-version c)
+            (when (missing-parent c)
+              (coerce-name (missing-parent c))))))
+
+
+;;;; Finding components
+
+(with-upgradability ()
+  (defgeneric resolve-dependency-combination (component combinator arguments)
+    (:documentation "Return a component satisfying the dependency specification (COMBINATOR . ARGUMENTS)
+in the context of COMPONENT"))
+
+  ;; Methods for find-component
+
+  ;; If the base component is a string, resolve it as a system, then if not nil follow the path.
+  (defmethod find-component ((base string) path &key registered)
+    (if-let ((s (if registered
+                    (registered-system base)
+                    (find-system base nil))))
+      (find-component s path :registered registered)))
+
+  ;; If the base component is a symbol, coerce it to a name if not nil, and resolve that.
+  ;; If nil, use the path as base if not nil, or else return nil.
+  (defmethod find-component ((base symbol) path &key registered)
+    (cond
+      (base (find-component (coerce-name base) path :registered registered))
+      (path (find-component path nil :registered registered))
+      (t    nil)))
+
+  ;; If the base component is a cons cell, resolve its car, and add its cdr to the path.
+  (defmethod find-component ((base cons) path &key registered)
+    (find-component (car base) (cons (cdr base) path) :registered registered))
+
+  ;; If the base component is a parent-component and the path a string, find the named child.
+  (defmethod find-component ((parent parent-component) (name string) &key registered)
+    (declare (ignorable registered))
+    (compute-children-by-name parent :only-if-needed-p t)
+    (values (gethash name (component-children-by-name parent))))
+
+  ;; If the path is a symbol, coerce it to a name if non-nil, or else just return the base.
+  (defmethod find-component (base (name symbol) &key registered)
+    (if name
+        (find-component base (coerce-name name) :registered registered)
+        base))
+
+  ;; If the path is a cons, first resolve its car as path, then its cdr.
+  (defmethod find-component ((c component) (name cons) &key registered)
+    (find-component (find-component c (car name) :registered registered)
+                    (cdr name) :registered registered))
+
+  ;; If the path is a component, return it, disregarding the base.
+  (defmethod find-component ((base t) (actual component) &key registered)
+    (declare (ignorable registered))
+    actual)
+
+  ;; Resolve dependency NAME in the context of a COMPONENT, with given optional VERSION constraint.
+  ;; This (private) function is used below by RESOLVE-DEPENDENCY-SPEC and by the :VERSION spec.
+  (defun resolve-dependency-name (component name &optional version)
+    (loop
+      (restart-case
+          (return
+            (let ((comp (find-component (component-parent component) name)))
+              (unless comp
+                (error 'missing-dependency
+                       :required-by component
+                       :requires name))
+              (when version
+                (unless (version-satisfies comp version)
+                  (error 'missing-dependency-of-version
+                         :required-by component
+                         :version version
+                         :requires name)))
+              comp))
+        (retry ()
+          :report (lambda (s)
+                    (format s (compatfmt "~@<Retry loading ~3i~_~A.~@:>") name))
+          :test
+          (lambda (c)
+            (or (null c)
+                (and (typep c 'missing-dependency)
+                     (eq (missing-required-by c) component)
+                     (equal (missing-requires c) name))))
+          (unless (component-parent component)
+            (let ((name (coerce-name name)))
+              (unset-asdf-cache-entry `(find-system ,name))))))))
+
+  ;; Resolve dependency specification DEP-SPEC in the context of COMPONENT.
+  ;; This is notably used by MAP-DIRECT-DEPENDENCIES to process the results of COMPONENT-DEPENDS-ON
+  ;; and by PARSE-DEFSYSTEM to process DEFSYSTEM-DEPENDS-ON.
+  (defun resolve-dependency-spec (component dep-spec)
+    (let ((component (find-component () component)))
+      (if (atom dep-spec)
+          (resolve-dependency-name component dep-spec)
+          (resolve-dependency-combination component (car dep-spec) (cdr dep-spec)))))
+
+  ;; Methods for RESOLVE-DEPENDENCY-COMBINATION to parse lists as dependency specifications.
+  (defmethod resolve-dependency-combination (component combinator arguments)
+    (parameter-error (compatfmt "~@<In ~S, bad dependency ~S for ~S~@:>")
+                     'resolve-dependency-combination (cons combinator arguments) component))
+
+  (defmethod resolve-dependency-combination (component (combinator (eql :feature)) arguments)
+    (when (featurep (first arguments))
+      (resolve-dependency-spec component (second arguments))))
+
+  (defmethod resolve-dependency-combination (component (combinator (eql :version)) arguments)
+    (resolve-dependency-name component (first arguments) (second arguments)))) ;; See lp#527788
+
+;;;; -------------------------------------------------------------------------
+;;;; Forcing
+
+(uiop/package:define-package :asdf/forcing
+  (:recycle :asdf/forcing :asdf/plan :asdf)
+  (:use :uiop/common-lisp :uiop :asdf/upgrade :asdf/session
+        :asdf/component :asdf/operation :asdf/system :asdf/system-registry)
+  (:export
+   #:forcing #:make-forcing #:forced #:forced-not #:performable-p
+   #:normalize-forced-systems #:normalize-forced-not-systems
+   #:action-forced-p #:action-forced-not-p))
+(in-package :asdf/forcing)
+
+;;;; Forcing
+(with-upgradability ()
+  (defclass forcing ()
+    (;; Can plans using this forcing be PERFORMed? A plan that has different force and force-not
+     ;; settings than the session can only be used for read-only queries that do not cause the
+     ;; status of any action to be raised.
+     (performable-p :initform nil :initarg :performable-p :reader performable-p)
+     ;; Parameters
+     (parameters :initform nil :initarg :parameters :reader parameters)
+     ;; Table of systems specified via :force arguments
+     (forced :initarg :forced :reader forced)
+     ;; Table of systems specified via :force-not argument (and/or immutable)
+     (forced-not :initarg :forced-not :reader forced-not)))
+
+  (defgeneric action-forced-p (forcing operation component)
+    (:documentation "Is this action forced to happen in this plan?"))
+  (defgeneric action-forced-not-p (forcing operation component)
+    (:documentation "Is this action forced to not happen in this plan?
+Takes precedence over action-forced-p."))
+
+  (defun normalize-forced-systems (force system)
+    "Given a SYSTEM on which operate is called and the specified FORCE argument,
+extract a hash-set of systems that are forced, or a predicate on system names,
+or NIL if none are forced, or :ALL if all are."
+    (etypecase force
+      ((or (member nil :all) hash-table function) force)
+      (cons (list-to-hash-set (mapcar #'coerce-name force)))
+      ((eql t) (when system (list-to-hash-set (list (coerce-name system)))))))
+
+  (defun normalize-forced-not-systems (force-not system)
+    "Given a SYSTEM on which operate is called, the specified FORCE-NOT argument,
+and the set of IMMUTABLE systems, extract a hash-set of systems that are effectively forced-not,
+or predicate on system names, or NIL if none are forced, or :ALL if all are."
+    (let ((requested
+            (etypecase force-not
+              ((or (member nil :all) hash-table function) force-not)
+              (cons (list-to-hash-set (mapcar #'coerce-name force-not)))
+              ((eql t) (if system (let ((name (coerce-name system)))
+                                    #'(lambda (x) (not (equal x name))))
+                           :all)))))
+      (if (and *immutable-systems* requested)
+          #'(lambda (x) (or (call-function requested x)
+                            (call-function *immutable-systems* x)))
+          (or *immutable-systems* requested))))
+
+  ;; TODO: shouldn't we be looking up the primary system name, rather than the system name?
+  (defun action-override-p (forcing operation component override-accessor)
+    "Given a plan, an action, and a function that given the plan accesses a set of overrides,
+i.e. force or force-not, see if the override applies to the current action."
+    (declare (ignore operation))
+    (call-function (funcall override-accessor forcing)
+                   (coerce-name (component-system (find-component () component)))))
+
+  (defmethod action-forced-p (forcing operation component)
+    (and
+     ;; Did the user ask us to re-perform the action?
+     (action-override-p forcing operation component 'forced)
+     ;; You really can't force a builtin system and :all doesn't apply to it.
+     (not (builtin-system-p (component-system component)))))
+
+  (defmethod action-forced-not-p (forcing operation component)
+    ;; Did the user ask us to not re-perform the action?
+    ;; NB: force-not takes precedence over force, as it should
+    (action-override-p forcing operation component 'forced-not))
+
+  ;; Null forcing means no forcing either way
+  (defmethod action-forced-p ((forcing null) (operation operation) (component component))
+    nil)
+  (defmethod action-forced-not-p ((forcing null) (operation operation) (component component))
+    nil)
+
+  (defun or-function (fun1 fun2)
+    (cond
+      ((or (null fun2) (eq fun1 :all)) fun1)
+      ((or (null fun1) (eq fun2 :all)) fun2)
+      (t #'(lambda (x) (or (call-function fun1 x) (call-function fun2 x))))))
+
+  (defun make-forcing (&key performable-p system
+                         (force nil force-p) (force-not nil force-not-p) &allow-other-keys)
+    (let* ((session-forcing (when *asdf-session* (forcing *asdf-session*)))
+           (system (and system (coerce-name system)))
+           (forced (normalize-forced-systems force system))
+           (forced-not (normalize-forced-not-systems force-not system))
+           (parameters `(,@(when force `(:force ,force))
+                         ,@(when force-not `(:force-not ,force-not))
+                         ,@(when (or (eq force t) (eq force-not t)) `(:system ,system))
+                         ,@(when performable-p `(:performable-p t))))
+           forcing)
+      (cond
+        ((not session-forcing)
+         (setf forcing (make-instance 'forcing
+                                      :performable-p performable-p :parameters parameters
+                                      :forced forced :forced-not forced-not))
+         (when (and performable-p *asdf-session*)
+           (setf (forcing *asdf-session*) forcing)))
+        (performable-p
+         (when (and (not (equal parameters (parameters session-forcing)))
+                    (or force-p force-not-p))
+           (parameter-error "~*~S and ~S arguments not allowed in a nested call to ~3:*~S ~
+unless identically to toplevel"
+                            (find-symbol* :operate :asdf) :force :force-not))
+         (setf forcing session-forcing))
+        (t
+         (setf forcing (make-instance 'forcing
+                           ;; Combine force and force-not with values from the toplevel-plan
+                           :parameters `(,@parameters :on-top-of ,(parameters session-forcing))
+                           :forced (or-function (forced session-forcing) forced)
+                           :forced-not (or-function (forced-not session-forcing) forced-not)))))
+      forcing))
+
+  (defmethod print-object ((forcing forcing) stream)
+    (print-unreadable-object (forcing stream :type t)
+      (format stream "~{~S~^ ~}" (parameters forcing))))
+
+  ;; During upgrade, the *asdf-session* may legitimately be NIL, so we must handle that case.
+  (defmethod forcing ((x null))
+    (if-let (session (toplevel-asdf-session))
+      (forcing session)
+      (make-forcing :performable-p t)))
+
+  ;; When performing a plan that is a list of actions, use the toplevel asdf sesssion forcing.
+  (defmethod forcing ((x cons)) (forcing (toplevel-asdf-session))))
+;;;; -------------------------------------------------------------------------
+;;;; Plan
+
+(uiop/package:define-package :asdf/plan
+  ;; asdf/action below is needed for required-components, traverse-action and traverse-sub-actions
+  ;; that used to live there before 3.2.0.
+  (:recycle :asdf/plan :asdf/action :asdf)
+  (:use :uiop/common-lisp :uiop :asdf/upgrade :asdf/session
+        :asdf/component :asdf/operation :asdf/action :asdf/lisp-action
+        :asdf/system :asdf/system-registry :asdf/find-component :asdf/forcing)
+  (:export
+   #:plan #:plan-traversal #:sequential-plan #:*plan-class*
+   #:action-status #:status-stamp #:status-index #:status-done-p #:status-keep-p #:status-need-p
+   #:action-already-done-p
+   #:+status-good+ #:+status-todo+ #:+status-void+
+   #:system-out-of-date #:action-up-to-date-p
+   #:circular-dependency #:circular-dependency-actions
+   #:needed-in-image-p
+   #:map-direct-dependencies #:reduce-direct-dependencies #:direct-dependencies
+   #:compute-action-stamp #:traverse-action #:record-dependency
+   #:make-plan #:plan-actions #:plan-actions-r #:perform-plan #:mark-as-done
+   #:required-components #:filtered-sequential-plan
+   #:plan-component-type #:plan-keep-operation #:plan-keep-component))
+(in-package :asdf/plan)
+
+;;;; Generic plan traversal class
+(with-upgradability ()
+  (defclass plan () ()
+    (:documentation "Base class for a plan based on which ASDF can build a system"))
+  (defclass plan-traversal (plan)
+    (;; The forcing parameters for this plan. Also indicates whether the plan is performable,
+     ;; in which case the forcing is the same as for the entire session.
+     (forcing :initform (forcing (toplevel-asdf-session)) :initarg :forcing :reader forcing))
+    (:documentation "Base class for plans that simply traverse dependencies"))
+  ;; Sequential plans (the default)
+  (defclass sequential-plan (plan-traversal)
+    ((actions-r :initform nil :accessor plan-actions-r))
+    (:documentation "Simplest, default plan class, accumulating a sequence of actions"))
+
+  (defgeneric plan-actions (plan)
+    (:documentation "Extract from a plan a list of actions to perform in sequence"))
+  (defmethod plan-actions ((plan list))
+    plan)
+  (defmethod plan-actions ((plan sequential-plan))
+    (reverse (plan-actions-r plan)))
+
+  (defgeneric record-dependency (plan operation component)
+    (:documentation "Record that, within PLAN, performing OPERATION on COMPONENT depends on all
+of the (OPERATION . COMPONENT) actions in the current ASDF session's VISITING-ACTION-LIST.
+
+You can get a single action which dominates the set of dependencies corresponding to this call with
+(first (visiting-action-list *asdf-session*))
+since VISITING-ACTION-LIST is a stack whose top action depends directly on its second action,
+and whose second action depends directly on its third action, and so forth."))
+
+  ;; No need to record a dependency to build a full graph, just accumulate nodes in order.
+  (defmethod record-dependency ((plan sequential-plan) (o operation) (c component))
+    (values)))
+
+(when-upgrading (:version "3.3.0")
+  (defmethod initialize-instance :after ((plan plan-traversal) &key &allow-other-keys)))
+
+
+;;;; Planned action status
+(with-upgradability ()
+  (defclass action-status ()
+    ((bits
+      :type fixnum :initarg :bits :reader status-bits
+      :documentation "bitmap describing the status of the action.")
+     (stamp
+      :type (or integer boolean) :initarg :stamp :reader status-stamp
+      :documentation "STAMP associated with the ACTION if it has been completed already in some
+previous session or image, T if it was done and builtin the image, or NIL if it needs to be done.")
+     (level
+      :type fixnum :initarg :level :initform 0 :reader status-level
+      :documentation "the highest (operate-level) at which the action was needed")
+     (index
+      :type (or integer null) :initarg :index :initform nil :reader status-index
+      :documentation "INDEX associated with the ACTION in the current session,
+or NIL if no the status is considered outside of a specific plan."))
+    (:documentation "Status of an action in a plan"))
+
+  ;; STAMP   KEEP-P DONE-P NEED-P     symbol bitmap  previously   currently
+  ;; not-nil   T      T      T     =>  GOOD     7    up-to-date   done (e.g. file previously loaded)
+  ;; not-nil   T      T     NIL    =>  HERE     6    up-to-date   unplanned yet done
+  ;; not-nil   T     NIL     T     =>  REDO     5    up-to-date   planned (e.g. file to load)
+  ;; not-nil   T     NIL    NIL    =>  SKIP     4    up-to-date   unplanned (e.g. file compiled)
+  ;; not-nil  NIL     T      T     =>  DONE     3    out-of-date  done
+  ;; not-nil  NIL     T     NIL    =>  WHAT     2    out-of-date  unplanned yet done(?)
+  ;;  NIL     NIL    NIL     T     =>  TODO     1    out-of-date  planned
+  ;;  NIL     NIL    NIL    NIL    =>  VOID     0    out-of-date  unplanned
+  ;;
+  ;; Note that a VOID status cannot happen as part of a transitive dependency of a wanted node
+  ;; while traversing a node with TRAVERSE-ACTION; it can only happen while checking whether an
+  ;; action is up-to-date with ACTION-UP-TO-DATE-P.
+  ;;
+  ;; When calling TRAVERSE-ACTION, the +need-bit+ is set,
+  ;; unless the action is up-to-date and not needed-in-image (HERE, SKIP).
+  ;; When PERFORMing an action, the +done-bit+ is set.
+  ;; When the +need-bit+ is set but not the +done-bit+, the level slot indicates which level of
+  ;; OPERATE it was last marked needed for; if it happens to be needed at a higher-level, then
+  ;; its urgency (and that of its transitive dependencies) must be escalated so that it will be
+  ;; done before the end of this level of operate.
+  ;;
+  ;; Also, when no ACTION-STATUS is associated to an action yet, NIL serves as a bottom value.
+  ;;
+  (defparameter +keep-bit+ 4)
+  (defparameter +done-bit+ 2)
+  (defparameter +need-bit+ 1)
+  (defparameter +good-bits+ 7)
+  (defparameter +todo-bits+ 1)
+  (defparameter +void-bits+ 0)
+
+  (defparameter +status-good+
+    (make-instance 'action-status :bits +good-bits+ :stamp t))
+  (defparameter +status-todo+
+    (make-instance 'action-status :bits +todo-bits+ :stamp nil))
+  (defparameter +status-void+
+    (make-instance 'action-status :bits +void-bits+ :stamp nil)))
+
+(with-upgradability ()
+  (defun make-action-status (&key bits stamp (level 0) index)
+    (check-type bits (integer 0 7))
+    (check-type stamp (or integer boolean))
+    (check-type level (integer 0 #.most-positive-fixnum))
+    (check-type index (or integer null))
+    (assert (eq (null stamp) (zerop (logand bits #.(logior +keep-bit+ +done-bit+)))) ()
+            "Bad action-status :bits ~S :stamp ~S" bits stamp)
+    (block nil
+      (when (and (null index) (zerop level))
+        (case bits
+          (#.+void-bits+ (return +status-void+))
+          (#.+todo-bits+ (return +status-todo+))
+          (#.+good-bits+ (when (eq stamp t) (return +status-good+)))))
+      (make-instance 'action-status :bits bits :stamp stamp :level level :index index)))
+
+  (defun status-keep-p (status)
+    (plusp (logand (status-bits status) #.+keep-bit+)))
+  (defun status-done-p (status)
+    (plusp (logand (status-bits status) #.+done-bit+)))
+  (defun status-need-p (status)
+    (plusp (logand (status-bits status) #.+need-bit+)))
+
+  (defun merge-action-status (status1 status2) ;; status-and
+    "Return the earliest status later than both status1 and status2"
+    (make-action-status
+     :bits (logand (status-bits status1) (status-bits status2))
+     :stamp (latest-timestamp (status-stamp status1) (status-stamp status2))
+     :level (min (status-level status1) (status-level status2))
+     :index (or (status-index status1) (status-index status2))))
+
+  (defun mark-status-needed (status &optional (level (operate-level))) ;; limited status-or
+    "Return the same status but with the need bit set, for the given level"
+    (if (and (status-need-p status)
+             (>= (status-level status) level))
+        status
+        (make-action-status
+         :bits (logior (status-bits status) +need-bit+)
+         :level (max level (status-level status))
+         :stamp (status-stamp status)
+         :index (status-index status))))
+
+  (defmethod print-object ((status action-status) stream)
+    (print-unreadable-object (status stream :type t)
+      (with-slots (bits stamp level index) status
+        (format stream "~{~S~^ ~}" `(:bits ,bits :stamp ,stamp :level ,level :index ,index)))))
+
+  (defgeneric action-status (plan operation component)
+    (:documentation "Returns the ACTION-STATUS associated to the action of OPERATION on COMPONENT
+in the PLAN, or NIL if the action wasn't visited yet as part of the PLAN."))
+
+  (defgeneric (setf action-status) (new-status plan operation component)
+    (:documentation "Sets the ACTION-STATUS associated to
+the action of OPERATION on COMPONENT in the PLAN"))
+
+  (defmethod action-status ((plan null) (o operation) (c component))
+    (multiple-value-bind (stamp done-p) (component-operation-time o c)
+      (if done-p
+          (make-action-status :bits #.+keep-bit+ :stamp stamp)
+          +status-void+)))
+
+  (defmethod (setf action-status) (new-status (plan null) (o operation) (c component))
+    (let ((times (component-operation-times c)))
+      (if (status-done-p new-status)
+          (setf (gethash o times) (status-stamp new-status))
+          (remhash o times)))
+    new-status)
+
+  ;; Handle FORCED-NOT: it makes an action return its current timestamp as status
+  (defmethod action-status ((p plan) (o operation) (c component))
+    ;; TODO: should we instead test something like:
+    ;; (action-forced-not-p plan operation (primary-system component))
+    (or (gethash (make-action o c) (visited-actions *asdf-session*))
+        (when (action-forced-not-p (forcing p) o c)
+          (let ((status (action-status nil o c)))
+            (setf (gethash (make-action o c) (visited-actions *asdf-session*))
+                  (make-action-status
+                   :bits +good-bits+
+                   :stamp (or (and status (status-stamp status)) t)
+                   :index (incf (total-action-count *asdf-session*))))))))
+
+  (defmethod (setf action-status) (new-status (p plan) (o operation) (c component))
+    (setf (gethash (make-action o c) (visited-actions *asdf-session*)) new-status))
+
+  (defmethod (setf action-status) :after
+      (new-status (p sequential-plan) (o operation) (c component))
+    (unless (status-done-p new-status)
+      (push (make-action o c) (plan-actions-r p)))))
+
+
+;;;; Is the action needed in this image?
+(with-upgradability ()
+  (defgeneric needed-in-image-p (operation component)
+    (:documentation "Is the action of OPERATION on COMPONENT needed in the current image
+to be meaningful, or could it just as well have been done in another Lisp image?"))
+
+  (defmethod needed-in-image-p ((o operation) (c component))
+    ;; We presume that actions that modify the filesystem don't need be run
+    ;; in the current image if they have already been done in another,
+    ;; and can be run in another process (e.g. a fork),
+    ;; whereas those that don't are meant to side-effect the current image and can't.
+    (not (output-files o c))))
+
+
+;;;; Visiting dependencies of an action and computing action stamps
+(with-upgradability ()
+  (defun map-direct-dependencies (operation component fun)
+    "Call FUN on all the valid dependencies of the given action in the given plan"
+    (loop :for (dep-o-spec . dep-c-specs) :in (component-depends-on operation component)
+          :for dep-o = (find-operation operation dep-o-spec)
+          :when dep-o
+            :do (loop :for dep-c-spec :in dep-c-specs
+                      :for dep-c = (and dep-c-spec (resolve-dependency-spec component dep-c-spec))
+                      :when (action-valid-p dep-o dep-c)
+                        :do (funcall fun dep-o dep-c))))
+
+  (defun reduce-direct-dependencies (operation component combinator seed)
+    "Reduce the direct dependencies to a value computed by iteratively calling COMBINATOR
+for each dependency action on the dependency's operation and component and an accumulator
+initialized with SEED."
+    (map-direct-dependencies
+     operation component
+     #'(lambda (dep-o dep-c) (setf seed (funcall combinator dep-o dep-c seed))))
+    seed)
+
+  (defun direct-dependencies (operation component)
+    "Compute a list of the direct dependencies of the action within the plan"
+    (reverse (reduce-direct-dependencies operation component #'acons nil)))
+
+  ;; In a distant future, get-file-stamp, component-operation-time and latest-stamp
+  ;; shall also be parametrized by the plan, or by a second model object,
+  ;; so they need not refer to the state of the filesystem,
+  ;; and the stamps could be cryptographic checksums rather than timestamps.
+  ;; Such a change remarkably would only affect COMPUTE-ACTION-STAMP.
+  (define-condition dependency-not-done (warning)
+    ((op
+      :initarg :op)
+     (component
+      :initarg :component)
+     (dep-op
+      :initarg :dep-op)
+     (dep-component
+      :initarg :dep-component)
+     (plan
+      :initarg :plan
+      :initform nil))
+    (:report (lambda (condition stream)
+               (with-slots (op component dep-op dep-component plan) condition
+                 (format stream "Computing just-done stamp ~@[in plan ~S~] for action ~S, but dependency ~S wasn't done yet!"
+                         plan
+                         (action-path (make-action op component))
+                         (action-path (make-action dep-op dep-component)))))))
+
+  (defmethod compute-action-stamp (plan (o operation) (c component) &key just-done)
+    ;; Given an action, figure out at what time in the past it has been done,
+    ;; or if it has just been done, return the time that it has.
+    ;; Returns two values:
+    ;; 1- the TIMESTAMP of the action if it has already been done and is up to date,
+    ;;   or NIL is either hasn't been done or is out of date.
+    ;;   (An ASDF extension could use a cryptographic digest instead.)
+    ;; 2- the DONE-IN-IMAGE-P boolean flag that is T if the action has already been done
+    ;;   in the current image, or NIL if it hasn't.
+    ;; Note that if e.g. LOAD-OP only depends on up-to-date files, but
+    ;; hasn't been done in the current image yet, then it can have a non-NIL timestamp,
+    ;; yet a NIL done-in-image-p flag: we can predict what timestamp it will have once loaded,
+    ;; i.e. that of the input-files.
+    ;; If just-done is NIL, these values return are the notional fields of
+    ;; a KEEP, REDO or TODO status (VOID is possible, but probably an error).
+    ;; If just-done is T, they are the notional fields of DONE status
+    ;; (or, if something went wrong, TODO).
+    (nest
+     (block ())
+     (let* ((dep-status ; collect timestamp from dependencies (or T if forced or out-of-date)
+             (reduce-direct-dependencies
+              o c
+              #'(lambda (do dc status)
+                  ;; out-of-date dependency: don't bother looking further
+                  (let ((action-status (action-status plan do dc)))
+                    (cond
+                      ((and action-status (or (status-keep-p action-status)
+                                              (and just-done (status-stamp action-status))))
+                       (merge-action-status action-status status))
+                      (just-done
+                       ;; It's OK to lose some ASDF action stamps during self-upgrade
+                       (unless (equal "asdf" (primary-system-name dc))
+                         (warn 'dependency-not-done
+                               :plan plan
+                               :op o :component c
+                               :dep-op do :dep-component dc))
+                       status)
+                      (t
+                       (return (values nil nil))))))
+              +status-good+))
+            (dep-stamp (status-stamp dep-status))))
+     (let* (;; collect timestamps from inputs, and exit early if any is missing
+            (in-files (input-files o c))
+            (in-stamps (mapcar #'get-file-stamp in-files))
+            (missing-in (loop :for f :in in-files :for s :in in-stamps :unless s :collect f))
+            (latest-in (timestamps-latest (cons dep-stamp in-stamps))))
+       (when (and missing-in (not just-done)) (return (values nil nil))))
+     (let* (;; collect timestamps from outputs, and exit early if any is missing
+            (out-files (remove-if 'null (output-files o c)))
+            (out-stamps (mapcar (if just-done 'register-file-stamp 'get-file-stamp) out-files))
+            (missing-out (loop :for f :in out-files :for s :in out-stamps :unless s :collect f))
+            (earliest-out (timestamps-earliest out-stamps)))
+       (when (and missing-out (not just-done)) (return (values nil nil))))
+     (let (;; Time stamps from the files at hand, and whether any is missing
+           (all-present (not (or missing-in missing-out)))
+           ;; Has any input changed since we last generated the files?
+           ;; Note that we use timestamp<= instead of timestamp< to play nice with generated files.
+           ;; Any race condition is intrinsic to the limited timestamp resolution.
+           (up-to-date-p (timestamp<= latest-in earliest-out))
+           ;; If everything is up to date, the latest of inputs and outputs is our stamp
+           (done-stamp (timestamps-latest (cons latest-in out-stamps))))
+       ;; Warn if some files are missing:
+       ;; either our model is wrong or some other process is messing with our files.
+       (when (and just-done (not all-present))
+         ;; Shouldn't that be an error instead?
+         (warn "~A completed without ~:[~*~;~*its input file~:p~2:*~{ ~S~}~*~]~
+                ~:[~; or ~]~:[~*~;~*its output file~:p~2:*~{ ~S~}~*~]"
+               (action-description o c)
+               missing-in (length missing-in) (and missing-in missing-out)
+               missing-out (length missing-out))))
+     (let (;; There are three kinds of actions:
+           (out-op (and out-files t)) ; those that create files on the filesystem
+           ;;(image-op (and in-files (null out-files))) ; those that load stuff into the image
+           ;;(null-op (and (null out-files) (null in-files))) ; placeholders that do nothing
+           ))
+     (if (or just-done ;; The done-stamp is valid: if we're just done, or
+             (and all-present ;; if all filesystem effects are up-to-date
+                  up-to-date-p
+                  (operation-done-p o c) ;; and there's no invalidating reason.
+                  (not (action-forced-p (forcing (or plan *asdf-session*)) o c))))
+         (values done-stamp ;; return the hard-earned timestamp
+                 (or just-done
+                     out-op ;; A file-creating op is done when all files are up to date.
+                     ;; An image-effecting operation is done when
+                     (and (status-done-p dep-status) ;; all the dependencies were done, and
+                          (multiple-value-bind (perform-stamp perform-done-p)
+                              (component-operation-time o c)
+                            (and perform-done-p ;; the op was actually run,
+                                 (equal perform-stamp done-stamp)))))) ;; with a matching stamp.
+         ;; done-stamp invalid: return a timestamp in an indefinite future, action not done yet
+         (values nil nil)))))
+
+
+;;;; The four different actual traversals:
+;; * TRAVERSE-ACTION o c T: Ensure all dependencies are either up-to-date in-image, or planned
+;; * TRAVERSE-ACTION o c NIL: Ensure all dependencies are up-to-date or planned, in-image or not
+;; * ACTION-UP-TO-DATE-P: Check whether some (defsystem-depends-on ?) dependencies are up to date
+;; * COLLECT-ACTION-DEPENDENCIES: Get the dependencies (filtered), don't change any status
+(with-upgradability ()
+
+  ;; Compute the action status for a newly visited action.
+  (defun compute-action-status (plan operation component need-p)
+    (multiple-value-bind (stamp done-p)
+        (compute-action-stamp plan operation component)
+      (assert (or stamp (not done-p)))
+      (make-action-status
+       :bits (logior (if stamp #.+keep-bit+ 0)
+                     (if done-p #.+done-bit+ 0)
+                     (if need-p #.+need-bit+ 0))
+       :stamp stamp
+       :level (operate-level)
+       :index (incf (total-action-count *asdf-session*)))))
+
+  ;; TRAVERSE-ACTION, in the context of a given PLAN object that accumulates dependency data,
+  ;; visits the action defined by its OPERATION and COMPONENT arguments,
+  ;; and all its transitive dependencies (unless already visited),
+  ;; in the context of the action being (or not) NEEDED-IN-IMAGE-P,
+  ;; i.e. needs to be done in the current image vs merely have been done in a previous image.
+  ;;
+  ;; TRAVERSE-ACTION updates the VISITED-ACTIONS entries for the action and for all its
+  ;; transitive dependencies (that haven't been sufficiently visited so far).
+  ;; It does not return any usable value.
+  ;;
+  ;; Note that for an XCVB-like plan with one-image-per-file-outputting-action,
+  ;; the below method would be insufficient, since it assumes a single image
+  ;; to traverse each node at most twice; non-niip actions would be traversed only once,
+  ;; but niip nodes could be traversed once per image, i.e. once plus once per non-niip action.
+
+  (defun traverse-action (plan operation component needed-in-image-p)
+    (block nil
+      (unless (action-valid-p operation component) (return))
+      ;; Record the dependency. This hook is needed by POIU, which tracks a full dependency graph,
+      ;; instead of just a dependency order as in vanilla ASDF.
+      ;; TODO: It is also needed to detect OPERATE-in-PERFORM.
+      (record-dependency plan operation component)
+      (while-visiting-action (operation component) ; maintain context, handle circularity.
+        ;; needed-in-image distinguishes b/w things that must happen in the
+        ;; current image and those things that simply need to have been done in a previous one.
+        (let* ((aniip (needed-in-image-p operation component)) ; action-specific needed-in-image
+               ;; effective niip: meaningful for the action and required by the plan as traversed
+               (eniip (and aniip needed-in-image-p))
+               ;; status: have we traversed that action previously, and if so what was its status?
+               (status (action-status plan operation component))
+               (level (operate-level)))
+          (when (and status
+                     (or (status-done-p status) ;; all done
+                         (and (status-need-p status) (<= level (status-level status))) ;; already visited
+                         (and (status-keep-p status) (not eniip)))) ;; up-to-date and not eniip
+            (return)) ; Already visited with sufficient need-in-image level!
+          (labels ((visit-action (niip) ; We may visit the action twice, once with niip NIL, then T
+                     (map-direct-dependencies ; recursively traverse dependencies
+                      operation component #'(lambda (o c) (traverse-action plan o c niip)))
+                     ;; AFTER dependencies have been traversed, compute action stamp
+                     (let* ((status (if status
+                                        (mark-status-needed status level)
+                                        (compute-action-status plan operation component t)))
+                            (out-of-date-p (not (status-keep-p status)))
+                            (to-perform-p (or out-of-date-p (and niip (not (status-done-p status))))))
+                       (cond ; it needs be done if it's out of date or needed in image but absent
+                         ((and out-of-date-p (not niip)) ; if we need to do it,
+                          (visit-action t)) ; then we need to do it *in the (current) image*!
+                         (t
+                          (setf (action-status plan operation component) status)
+                          (when (status-done-p status)
+                            (setf (component-operation-time operation component)
+                                  (status-stamp status)))
+                          (when to-perform-p ; if it needs to be added to the plan, count it
+                            (incf (planned-action-count *asdf-session*))
+                            (unless aniip ; if it's output-producing, count it
+                              (incf (planned-output-action-count *asdf-session*)))))))))
+            (visit-action eniip)))))) ; visit the action
+
+  ;; NB: This is not an error, not a warning, but a normal expected condition,
+  ;; to be to signaled by FIND-SYSTEM when it detects an out-of-date system,
+  ;; *before* it tries to replace it with a new definition.
+  (define-condition system-out-of-date (condition)
+    ((name :initarg :name :reader component-name))
+    (:documentation "condition signaled when a system is detected as being out of date")
+    (:report (lambda (c s)
+               (format s "system ~A is out of date" (component-name c)))))
+
+  (defun action-up-to-date-p (plan operation component)
+    "Check whether an action was up-to-date at the beginning of the session.
+Update the VISITED-ACTIONS table with the known status, but don't add anything to the PLAN."
+    (block nil
+      (unless (action-valid-p operation component) (return t))
+      (while-visiting-action (operation component) ; maintain context, handle circularity.
+        ;; Do NOT record the dependency: it might be out of date.
+        (let ((status (or (action-status plan operation component)
+                          (setf (action-status plan operation component)
+                                (let ((dependencies-up-to-date-p
+                                       (handler-case
+                                           (block nil
+                                             (map-direct-dependencies
+                                              operation component
+                                              #'(lambda (o c)
+                                                  (unless (action-up-to-date-p plan o c)
+                                                    (return nil))))
+                                             t)
+                                         (system-out-of-date () nil))))
+                                  (if dependencies-up-to-date-p
+                                      (compute-action-status plan operation component nil)
+                                      +status-void+))))))
+          (and (status-keep-p status) (status-stamp status)))))))
+
+
+;;;; Incidental traversals
+
+;;; Making a FILTERED-SEQUENTIAL-PLAN can be used to, e.g., all of the source
+;;; files required by a bundling operation.
+(with-upgradability ()
+  (defclass filtered-sequential-plan (sequential-plan)
+    ((component-type :initform t :initarg :component-type :reader plan-component-type)
+     (keep-operation :initform t :initarg :keep-operation :reader plan-keep-operation)
+     (keep-component :initform t :initarg :keep-component :reader plan-keep-component))
+    (:documentation "A variant of SEQUENTIAL-PLAN that only records a subset of actions."))
+
+  (defmethod initialize-instance :after ((plan filtered-sequential-plan)
+                                         &key system other-systems)
+    ;; Ignore force and force-not, rely on other-systems:
+    ;; force traversal of what we're interested in, i.e. current system or also others;
+    ;; force-not traversal of what we're not interested in, i.e. other systems unless other-systems.
+    (setf (slot-value plan 'forcing)
+          (make-forcing :system system :force :all :force-not (if other-systems nil t))))
+
+  (defmethod plan-actions ((plan filtered-sequential-plan))
+    (with-slots (keep-operation keep-component) plan
+      (loop :for action :in (call-next-method)
+        :as o = (action-operation action)
+        :as c = (action-component action)
+        :when (and (typep o keep-operation) (typep c keep-component))
+        :collect (make-action o c))))
+
+  (defun collect-action-dependencies (plan operation component)
+    (when (action-valid-p operation component)
+      (while-visiting-action (operation component) ; maintain context, handle circularity.
+        (let ((action (make-action operation component)))
+          (unless (nth-value 1 (gethash action (visited-actions *asdf-session*)))
+            (setf (gethash action (visited-actions *asdf-session*)) nil)
+            (when (and (typep component (plan-component-type plan))
+                       (not (action-forced-not-p (forcing plan) operation component)))
+              (map-direct-dependencies operation component
+                                       #'(lambda (o c) (collect-action-dependencies plan o c)))
+              (push action (plan-actions-r plan))))))))
+
+  (defgeneric collect-dependencies (operation component &key &allow-other-keys)
+    (:documentation "Given an action, build a plan for all of its dependencies."))
+  (define-convenience-action-methods collect-dependencies (operation component &key))
+  (defmethod collect-dependencies ((operation operation) (component component)
+                                   &rest keys &key &allow-other-keys)
+    (let ((plan (apply 'make-instance 'filtered-sequential-plan
+                       :system (component-system component) keys)))
+      (loop :for action :in (direct-dependencies operation component)
+        :do (collect-action-dependencies plan (action-operation action) (action-component action)))
+      (plan-actions plan)))
+
+  (defun required-components (system &rest keys &key (goal-operation 'load-op) &allow-other-keys)
+    "Given a SYSTEM and a GOAL-OPERATION (default LOAD-OP), traverse the dependencies and
+return a list of the components involved in building the desired action."
+    (with-asdf-session (:override t)
+      (remove-duplicates
+       (mapcar 'action-component
+               (apply 'collect-dependencies goal-operation system
+                      (remove-plist-key :goal-operation keys)))
+       :from-end t))))
+
+
+;;;; High-level interface: make-plan, perform-plan
+(with-upgradability ()
+  (defgeneric make-plan (plan-class operation component &key &allow-other-keys)
+    (:documentation "Generate and return a plan for performing OPERATION on COMPONENT."))
+  (define-convenience-action-methods make-plan (plan-class operation component &key))
+
+  (defgeneric mark-as-done (plan-class operation component)
+    (:documentation "Mark an action as done in a plan, after performing it."))
+  (define-convenience-action-methods mark-as-done (plan-class operation component))
+
+  (defgeneric perform-plan (plan &key)
+    (:documentation "Actually perform a plan and build the requested actions"))
+
+  (defparameter* *plan-class* 'sequential-plan
+    "The default plan class to use when building with ASDF")
+
+  (defmethod make-plan (plan-class (o operation) (c component) &rest keys &key &allow-other-keys)
+    (with-asdf-session ()
+      (let ((plan (apply 'make-instance (or plan-class *plan-class*) keys)))
+        (traverse-action plan o c t)
+        plan)))
+
+  (defmethod perform-plan :around ((plan t) &key)
+    (assert (performable-p (forcing plan)) () "plan not performable")
+    (let ((*package* *package*)
+          (*readtable* *readtable*))
+      (with-compilation-unit () ;; backward-compatibility.
+        (call-next-method))))   ;; Going forward, see deferred-warning support in lisp-build.
+
+  (defun action-already-done-p (plan operation component)
+    (if-let (status (action-status plan operation component))
+      (status-done-p status)))
+
+  (defmethod perform-plan ((plan t) &key)
+    (loop :for action :in (plan-actions plan)
+      :as o = (action-operation action)
+      :as c = (action-component action) :do
+      (unless (action-already-done-p plan o c)
+        (perform-with-restarts o c)
+        (mark-as-done plan o c))))
+
+  (defmethod mark-as-done ((plan plan) (o operation) (c component))
+    (let ((plan-status (action-status plan o c))
+          (perform-status (action-status nil o c)))
+      (assert (and (status-stamp perform-status) (status-keep-p perform-status)) ()
+              "Just performed ~A but failed to mark it done" (action-description o c))
+      (setf (action-status plan o c)
+            (make-action-status
+             :bits (logior (status-bits plan-status) +done-bit+)
+             :stamp (status-stamp perform-status)
+             :level (status-level plan-status)
+             :index (status-index plan-status))))))
+;;;; -------------------------------------------------------------------------
+;;;; Invoking Operations
+
+(uiop/package:define-package :asdf/operate
+  (:recycle :asdf/operate :asdf)
+  (:use :uiop/common-lisp :uiop :asdf/upgrade :asdf/session
+        :asdf/component :asdf/system :asdf/system-registry :asdf/find-component
+        :asdf/operation :asdf/action :asdf/lisp-action :asdf/forcing :asdf/plan)
+  (:export
+   #:operate #:oos #:build-op #:make
+   #:load-system #:load-systems #:load-systems*
+   #:compile-system #:test-system #:require-system #:module-provide-asdf
+   #:component-loaded-p #:already-loaded-systems
+   #:recursive-operate))
+(in-package :asdf/operate)
+
+(with-upgradability ()
+  (defgeneric operate (operation component &key)
+    (:documentation
+     "Operate does mainly four things for the user:
+
+1. Resolves the OPERATION designator into an operation object.
+   OPERATION is typically a symbol denoting an operation class, instantiated with MAKE-OPERATION.
+2. Resolves the COMPONENT designator into a component object.
+   COMPONENT is typically a string or symbol naming a system, loaded from disk using FIND-SYSTEM.
+3. It then calls MAKE-PLAN with the operation and system as arguments.
+4. Finally calls PERFORM-PLAN on the resulting plan to actually build the system.
+
+The entire computation is wrapped in WITH-COMPILATION-UNIT and error handling code.
+If a VERSION argument is supplied, then operate also ensures that the system found satisfies it
+using the VERSION-SATISFIES method.
+If a PLAN-CLASS argument is supplied, that class is used for the plan.
+If a PLAN-OPTIONS argument is supplied, the options are passed to the plan.
+
+The :FORCE or :FORCE-NOT argument to OPERATE can be:
+  T to force the inside of the specified system to be rebuilt (resp. not),
+    without recursively forcing the other systems we depend on.
+  :ALL to force all systems including other systems we depend on to be rebuilt (resp. not).
+  (SYSTEM1 SYSTEM2 ... SYSTEMN) to force systems named in a given list
+:FORCE-NOT has precedence over :FORCE; builtin systems cannot be forced.
+
+For backward compatibility, all keyword arguments are passed to MAKE-OPERATION
+when instantiating a new operation, that will in turn be inherited by new operations.
+But do NOT depend on it, for this is deprecated behavior."))
+
+  (define-convenience-action-methods operate (operation component &key)
+    :if-no-component (error 'missing-component :requires component))
+
+  ;; This method ensures that an ASDF upgrade is attempted as the very first thing,
+  ;; with suitable state preservation in case in case it actually happens,
+  ;; and that a few suitable dynamic bindings are established.
+  (defmethod operate :around (operation component &rest keys
+                              &key verbose
+                                (on-warnings *compile-file-warnings-behaviour*)
+                                (on-failure *compile-file-failure-behaviour*))
+    (nest
+     (with-asdf-session ())
+     (let* ((operation-remaker ;; how to remake the operation after ASDF was upgraded (if it was)
+             (etypecase operation
+               (operation (let ((name (type-of operation)))
+                            #'(lambda () (make-operation name))))
+               ((or symbol string) (constantly operation))))
+            (component-path (typecase component ;; to remake the component after ASDF upgrade
+                              (component (component-find-path component))
+                              (t component)))
+            (system-name (labels ((first-name (x)
+                                    (etypecase x
+                                      ((or string symbol) x) ; NB: includes the NIL case.
+                                      (cons (or (first-name (car x)) (first-name (cdr x)))))))
+                           (coerce-name (first-name component-path)))))
+       (apply 'make-forcing :performable-p t :system system-name keys)
+       ;; Before we operate on any system, make sure ASDF is up-to-date,
+       ;; for if an upgrade is ever attempted at any later time, there may be BIG trouble.
+       (unless (asdf-upgraded-p (toplevel-asdf-session))
+         (setf (asdf-upgraded-p (toplevel-asdf-session)) t)
+         (when (upgrade-asdf)
+           ;; If we were upgraded, restart OPERATE the hardest of ways, for
+           ;; its function may have been redefined.
+           (return-from operate
+             (with-asdf-session (:override t :override-cache t)
+               (apply 'operate (funcall operation-remaker) component-path keys))))))
+      ;; Setup proper bindings around any operate call.
+     (let* ((*verbose-out* (and verbose *standard-output*))
+            (*compile-file-warnings-behaviour* on-warnings)
+            (*compile-file-failure-behaviour* on-failure)))
+     (unwind-protect
+          (progn
+            (incf (operate-level))
+            (call-next-method))
+       (decf (operate-level)))))
+
+  (defmethod operate :before ((operation operation) (component component)
+                              &key version)
+    (unless (version-satisfies component version)
+      (error 'missing-component-of-version :requires component :version version))
+    (record-dependency nil operation component))
+
+  (defmethod operate ((operation operation) (component component)
+                      &key plan-class plan-options)
+    (let ((plan (apply 'make-plan plan-class operation component
+                       :forcing (forcing *asdf-session*) plan-options)))
+      (perform-plan plan)
+      (values operation plan)))
+
+  (defun oos (operation component &rest args &key &allow-other-keys)
+    (apply 'operate operation component args))
+
+  (setf (documentation 'oos 'function)
+        (format nil "Short for _operate on system_ and an alias for the OPERATE function.~%~%~a"
+                (documentation 'operate 'function)))
+
+  (define-condition recursive-operate (warning)
+    ((operation :initarg :operation :reader condition-operation)
+     (component :initarg :component :reader condition-component)
+     (action :initarg :action :reader condition-action))
+    (:report (lambda (c s)
+               (format s (compatfmt "~@<Deprecated recursive use of (~S '~S '~S) while visiting ~S ~
+- please use proper dependencies instead~@:>")
+                       'operate
+                       (type-of (condition-operation c))
+                       (component-find-path (condition-component c))
+                       (action-path (condition-action c)))))))
+
+;;;; Common operations
+(when-upgrading ()
+  (defmethod component-depends-on ((o prepare-op) (s system))
+    (call-next-method)))
+(with-upgradability ()
+  (defclass build-op (non-propagating-operation) ()
+    (:documentation "Since ASDF3, BUILD-OP is the recommended 'master' operation,
+to operate by default on a system or component, via the function BUILD.
+Its meaning is configurable via the :BUILD-OPERATION option of a component.
+which typically specifies the name of a specific operation to which to delegate the build,
+as a symbol or as a string later read as a symbol (after loading the defsystem-depends-on);
+if NIL is specified (the default), BUILD-OP falls back to LOAD-OP,
+that will load the system in the current image."))
+  (defmethod component-depends-on ((o build-op) (c component))
+    `((,(or (component-build-operation c) 'load-op) ,c)
+      ,@(call-next-method)))
+
+  (defun make (system &rest keys)
+    "The recommended way to interact with ASDF3.1 is via (ASDF:MAKE :FOO).
+It will build system FOO using the operation BUILD-OP,
+the meaning of which is configurable by the system, and
+defaults to LOAD-OP, to load it in current image."
+    (apply 'operate 'build-op system keys)
+    t)
+
+  (defun load-system (system &rest keys &key force force-not verbose version &allow-other-keys)
+    "Shorthand for `(operate 'asdf:load-op system)`. See OPERATE for details."
+    (declare (ignore force force-not verbose version))
+    (apply 'operate 'load-op system keys)
+    t)
+
+  (defun load-systems* (systems &rest keys)
+    "Loading multiple systems at once."
+    (dolist (s systems) (apply 'load-system s keys)))
+
+  (defun load-systems (&rest systems)
+    "Loading multiple systems at once."
+    (load-systems* systems))
+
+  (defun compile-system (system &rest args &key force force-not verbose version &allow-other-keys)
+    "Shorthand for `(asdf:operate 'asdf:compile-op system)`. See OPERATE for details."
+    (declare (ignore force force-not verbose version))
+    (apply 'operate 'compile-op system args)
+    t)
+
+  (defun test-system (system &rest args &key force force-not verbose version &allow-other-keys)
+    "Shorthand for `(asdf:operate 'asdf:test-op system)`. See OPERATE for details."
+    (declare (ignore force force-not verbose version))
+    (apply 'operate 'test-op system args)
+    t))
+
+;;;;; Define the function REQUIRE-SYSTEM, that, similarly to REQUIRE,
+;; only tries to load its specified target if it's not loaded yet.
+(with-upgradability ()
+  (defun component-loaded-p (component)
+    "Has the given COMPONENT been successfully loaded in the current image (yet)?
+Note that this returns true even if the component is not up to date."
+    (if-let ((component (find-component component () :registered t)))
+      (nth-value 1 (component-operation-time (make-operation 'load-op) component))))
+
+  (defun already-loaded-systems ()
+    "return a list of the names of the systems that have been successfully loaded so far"
+    (mapcar 'coerce-name (remove-if-not 'component-loaded-p (registered-systems*)))))
+
+
+;;;; Define the class REQUIRE-SYSTEM, to be hooked into CL:REQUIRE when possible,
+;; i.e. for ABCL, CLISP, ClozureCL, CMUCL, ECL, MKCL and SBCL
+;; Note that despite the two being homonyms, the _function_ require-system
+;; and the _class_ require-system are quite distinct entities, fulfilling independent purposes.
+(with-upgradability ()
+  (defvar *modules-being-required* nil)
+
+  (defclass require-system (system)
+    ((module :initarg :module :initform nil :accessor required-module))
+    (:documentation "A SYSTEM subclass whose processing is handled by
+the implementation's REQUIRE rather than by internal ASDF mechanisms."))
+
+  (defmethod perform ((o compile-op) (c require-system))
+    nil)
+
+  (defmethod perform ((o load-op) (s require-system))
+    (let* ((module (or (required-module s) (coerce-name s)))
+           (*modules-being-required* (cons module *modules-being-required*)))
+      (assert (null (component-children s)))
+      (require module)))
+
+  (defmethod resolve-dependency-combination (component (combinator (eql :require)) arguments)
+    (unless (and (length=n-p arguments 1)
+                 (typep (car arguments) '(or string (and symbol (not null)))))
+      (parameter-error (compatfmt "~@<In ~S, bad dependency ~S for ~S. ~S takes one argument, a string or non-null symbol~@:>")
+                       'resolve-dependency-combination
+                       (cons combinator arguments) component combinator))
+    ;; :require must be prepared for some implementations providing modules using ASDF,
+    ;; as SBCL used to do, and others may might do. Thus, the system provided in the end
+    ;; would be a downcased name as per module-provide-asdf above. For the same reason,
+    ;; we cannot assume that the system in the end will be of type require-system,
+    ;; but must check whether we can use find-system and short-circuit cl:require.
+    ;; Otherwise, calling cl:require could result in nasty reentrant calls between
+    ;; cl:require and asdf:operate that could potentially blow up the stack,
+    ;; all the while defeating the consistency of the dependency graph.
+    (let* ((module (car arguments)) ;; NB: we already checked that it was not null
+           ;; CMUCL, MKCL, SBCL like their module names to be all upcase.
+           (module-name (string module))
+           (system-name (string-downcase module))
+           (system (find-system system-name nil)))
+      (or system (let ((system (make-instance 'require-system :name system-name :module module-name)))
+                   (register-system system)
+                   system))))
+
+  (defun module-provide-asdf (name)
+    ;; We must use string-downcase, because modules are traditionally specified as symbols,
+    ;; that implementations traditionally normalize as uppercase, for which we seek a system
+    ;; with a name that is traditionally in lowercase. Case is lost along the way. That's fine.
+    ;; We could make complex, non-portable rules to try to preserve case, and just documenting
+    ;; them would be a hell that it would be a disservice to inflict on users.
+    (let ((module-name (string name))
+          (system-name (string-downcase name)))
+      (unless (member module-name *modules-being-required* :test 'equal)
+        (let ((*modules-being-required* (cons module-name *modules-being-required*))
+              #+sbcl (sb-impl::*requiring* (remove module-name sb-impl::*requiring* :test 'equal)))
+          (handler-bind
+              (((or style-warning recursive-operate) #'muffle-warning)
+               (missing-component (constantly nil))
+               (fatal-condition
+                #'(lambda (e)
+                    (format *error-output* (compatfmt "~@<ASDF could not load ~(~A~) because ~A.~@:>~%")
+                            name e))))
+            (let ((*verbose-out* (make-broadcast-stream)))
+              (let ((system (find-system system-name nil)))
+                (when system
+                  ;; Do not use require-system after all, use load-system:
+                  ;; on the one hand, REQUIRE already uses *MODULES* not to load something twice,
+                  ;; on the other hand, REQUIRE-SYSTEM uses FORCE-NOT which may conflict with
+                  ;; the toplevel session forcing settings.
+                  (load-system system :verbose nil)
+                  t)))))))))
+
+
+;;;; Some upgrade magic
+(with-upgradability ()
+  (defun restart-upgraded-asdf ()
+    ;; If we're in the middle of something, restart it.
+    (let ((systems-being-defined
+           (when *asdf-session*
+             (prog1
+                 (loop :for k :being :the hash-keys :of (asdf-cache)
+                   :when (eq (first k) 'find-system) :collect (second k))
+               (clrhash (asdf-cache))))))
+      ;; Regardless, clear defined systems, since they might be invalid
+      ;; after an incompatible ASDF upgrade.
+      (clear-registered-systems)
+      ;; The configuration also may have to be upgraded.
+      (upgrade-configuration)
+      ;; If we were in the middle of an operation, be sure to restore the system being defined.
+      (dolist (s systems-being-defined) (find-system s nil))))
+  (register-hook-function '*post-upgrade-cleanup-hook* 'restart-upgraded-asdf))
+;;;; -------------------------------------------------------------------------
+;;;; Finding systems
+
+(uiop/package:define-package :asdf/find-system
+  (:recycle :asdf/find-system :asdf)
+  (:use :uiop/common-lisp :uiop :asdf/upgrade
+        :asdf/session :asdf/component :asdf/system :asdf/operation :asdf/action :asdf/lisp-action
+        :asdf/find-component :asdf/system-registry :asdf/plan :asdf/operate)
+  (:import-from #:asdf/component #:%additional-input-files)
+  (:export
+   #:find-system #:locate-system #:load-asd #:define-op
+   #:load-system-definition-error #:error-name #:error-pathname #:error-condition))
+(in-package :asdf/find-system)
+
+(with-upgradability ()
+  (define-condition load-system-definition-error (system-definition-error)
+    ((name :initarg :name :reader error-name)
+     (pathname :initarg :pathname :reader error-pathname)
+     (condition :initarg :condition :reader error-condition))
+    (:report (lambda (c s)
+               (format s (compatfmt "~@<Error while trying to load definition for system ~A from pathname ~A: ~3i~_~A~@:>")
+                       (error-name c) (error-pathname c) (error-condition c)))))
+
+
+  ;;; Methods for find-system
+
+  ;; Reject NIL as a system designator.
+  (defmethod find-system ((name null) &optional (error-p t))
+    (when error-p
+      (sysdef-error (compatfmt "~@<NIL is not a valid system name~@:>"))))
+
+  ;; Default method for find-system: resolve the argument using COERCE-NAME.
+  (defmethod find-system (name &optional (error-p t))
+    (find-system (coerce-name name) error-p))
+
+  (defun find-system-if-being-defined (name)
+    ;; This function finds systems being defined *in the current ASDF session*, as embodied by
+    ;; its session cache, even before they are fully defined and registered in *registered-systems*.
+    ;; The purpose of this function is to prevent races between two files that might otherwise
+    ;; try overwrite each other's system objects, resulting in infinite loops and stack overflow.
+    ;; This function explicitly MUST NOT find definitions merely registered in previous sessions.
+    ;; NB: this function depends on a corresponding side-effect in parse-defsystem;
+    ;; the precise protocol between the two functions may change in the future (or not).
+    (first (gethash `(find-system ,(coerce-name name)) (asdf-cache))))
+
+  (defclass define-op (non-propagating-operation) ()
+    (:documentation "An operation to record dependencies on loading a .asd file."))
+
+  (defmethod record-dependency ((plan null) (operation t) (component t))
+    (unless (or (typep operation 'define-op)
+                (and (typep operation 'load-op)
+                     (typep component 'system)
+                     (equal "asdf" (coerce-name component))))
+      (if-let ((action (first (visiting-action-list *asdf-session*))))
+        (let ((parent-operation (action-operation action))
+              (parent-component (action-component action)))
+          (cond
+            ((and (typep parent-operation 'define-op)
+                  (typep parent-component 'system))
+             (let ((action (cons operation component)))
+               (unless (gethash action (definition-dependency-set parent-component))
+                 (push (cons operation component) (definition-dependency-list parent-component))
+                 (setf (gethash action (definition-dependency-set parent-component)) t))))
+            (t
+             (warn 'recursive-operate
+                   :operation operation :component component :action action)))))))
+
+  (defmethod component-depends-on ((o define-op) (s system))
+    `(;;NB: 1- ,@(system-defsystem-depends-on s)) ; Should be already included in the below.
+      ;; 2- We don't call-next-method to avoid other methods
+      ,@(loop :for (o . c) :in (definition-dependency-list s) :collect (list o c))))
+
+  (defmethod component-depends-on ((o operation) (s system))
+    `(,@(when (and (not (typep o 'define-op))
+                   (or (system-source-file s) (definition-dependency-list s)))
+              `((define-op ,(primary-system-name s))))
+      ,@(call-next-method)))
+
+  (defmethod perform ((o operation) (c undefined-system))
+    (sysdef-error "Trying to use undefined or incompletely defined system ~A" (coerce-name c)))
+
+  ;; TODO: could this file be refactored so that locate-system is merely
+  ;; the cache-priming call to input-files here?
+  (defmethod input-files ((o define-op) (s system))
+    (if-let ((asd (system-source-file s))) (list asd)))
+
+  (defmethod perform ((o define-op) (s system))
+    (nest
+     (if-let ((pathname (first (input-files o s)))))
+     (let ((readtable *readtable*) ;; save outer syntax tables. TODO: proper syntax-control
+           (print-pprint-dispatch *print-pprint-dispatch*)))
+     (with-standard-io-syntax)
+     (let ((*print-readably* nil)
+           ;; Note that our backward-compatible *readtable* is
+           ;; a global readtable that gets globally side-effected. Ouch.
+           ;; Same for the *print-pprint-dispatch* table.
+           ;; We should do something about that for ASDF3 if possible, or else ASDF4.
+           (*readtable* readtable) ;; restore inside syntax table
+           (*print-pprint-dispatch* print-pprint-dispatch)
+           (*package* (find-package :asdf-user))
+           (*default-pathname-defaults*
+            ;; resolve logical-pathnames so they won't wreak havoc in parsing namestrings.
+            (pathname-directory-pathname (physicalize-pathname pathname)))))
+     (handler-bind
+         (((and error (not missing-component))
+           #'(lambda (condition)
+               (error 'load-system-definition-error
+                      :name (coerce-name s) :pathname pathname :condition condition))))
+       (asdf-message (compatfmt "~&~@<; ~@;Loading system definition~@[ for ~A~] from ~A~@:>~%")
+                     (coerce-name s) pathname)
+       ;; dependencies will depend on what's loaded via definition-dependency-list
+       (unset-asdf-cache-entry `(component-depends-on ,o ,s))
+       (unset-asdf-cache-entry `(input-files ,o ,s)))
+     (load* pathname :external-format (encoding-external-format (detect-encoding pathname)))))
+
+  (defun load-asd (pathname &key name)
+    "Load system definitions from PATHNAME.
+NAME if supplied is the name of a system expected to be defined in that file.
+
+Do NOT try to load a .asd file directly with CL:LOAD. Always use ASDF:LOAD-ASD."
+    (with-asdf-session ()
+      ;; TODO: use OPERATE, so we consult the cache and only load once per session.
+      (flet ((do-it (o c) (operate o c)))
+        (let ((primary-name (primary-system-name (or name (pathname-name pathname))))
+              (operation (make-operation 'define-op)))
+          (if-let (system (registered-system primary-name))
+            (progn
+              ;; We already determine this to be obsolete ---
+              ;; or should we move some tests from find-system to check for up-to-date-ness here?
+              (setf (component-operation-time operation system) t
+                    (definition-dependency-list system) nil
+                    (definition-dependency-set system) (list-to-hash-set nil))
+              (do-it operation system))
+            (let ((system (make-instance 'undefined-system
+                                         :name primary-name :source-file pathname)))
+              (register-system system)
+              (unwind-protect (do-it operation system)
+                (when (typep system 'undefined-system)
+                  (clear-system system)))))))))
+
+  (defvar *old-asdf-systems* (make-hash-table :test 'equal))
+
+  ;; (Private) function to check that a system that was found isn't an asdf downgrade.
+  ;; Returns T if everything went right, NIL if the system was an ASDF at an older version,
+  ;; or UIOP of the same or older version, that shall not be loaded.
+  ;; Also issue a warning if it was a strictly older version of ASDF.
+  (defun check-not-old-asdf-system (name pathname)
+    (or (not (member name '("asdf" "uiop") :test 'equal))
+        (null pathname)
+        (let* ((asdfp (equal name "asdf")) ;; otherwise, it's uiop
+               (version-pathname
+                (subpathname pathname "version" :type (if asdfp "lisp-expr" "lisp")))
+               (version (and (probe-file* version-pathname :truename nil)
+                             (read-file-form version-pathname :at (if asdfp '(0) '(2 2 2)))))
+               (old-version (asdf-version)))
+          (cond
+            ;; Same version is OK for ASDF, to allow loading from modified source.
+            ;; However, do *not* load UIOP of the exact same version:
+            ;; it was already loaded it as part of ASDF and would only be double-loading.
+            ;; Be quiet about it, though, since it's a normal situation.
+            ((equal old-version version) asdfp)
+            ((version< old-version version) t) ;; newer version: Good!
+            (t ;; old version: bad
+             (ensure-gethash
+              (list (namestring pathname) version) *old-asdf-systems*
+              #'(lambda ()
+                  (let ((old-pathname (system-source-file (registered-system "asdf"))))
+                    (if asdfp
+                        (warn "~@<~
+        You are using ASDF version ~A ~:[(probably from (require \"asdf\") ~
+        or loaded by quicklisp)~;from ~:*~S~] and have an older version of ASDF ~
+        ~:[(and older than 2.27 at that)~;~:*~A~] registered at ~S. ~
+        Having an ASDF installed and registered is the normal way of configuring ASDF to upgrade itself, ~
+        and having an old version registered is a configuration error. ~
+        ASDF will ignore this configured system rather than downgrade itself. ~
+        In the future, you may want to either: ~
+        (a) upgrade this configured ASDF to a newer version, ~
+        (b) install a newer ASDF and register it in front of the former in your configuration, or ~
+        (c) uninstall or unregister this and any other old version of ASDF from your configuration. ~
+        Note that the older ASDF might be registered implicitly through configuration inherited ~
+        from your system installation, in which case you might have to specify ~
+        :ignore-inherited-configuration in your in your ~~/.config/common-lisp/source-registry.conf ~
+        or other source-registry configuration file, environment variable or lisp parameter. ~
+        Indeed, a likely offender is an obsolete version of the cl-asdf debian or ubuntu package, ~
+        that you might want to upgrade (if a recent enough version is available) ~
+        or else remove altogether (since most implementations ship with a recent asdf); ~
+        if you lack the system administration rights to upgrade or remove this package, ~
+        then you might indeed want to either install and register a more recent version, ~
+        or use :ignore-inherited-configuration to avoid registering the old one. ~
+        Please consult ASDF documentation and/or experts.~@:>~%"
+                              old-version old-pathname version pathname)
+                        ;; NB: for UIOP, don't warn, just ignore.
+                        (warn "ASDF ~A (from ~A), UIOP ~A (from ~A)"
+                              old-version old-pathname version pathname)
+                        ))))
+             nil))))) ;; only issue the warning the first time, but always return nil
+
+  (defun locate-system (name)
+    "Given a system NAME designator, try to locate where to load the system from.
+Returns six values: FOUNDP FOUND-SYSTEM PATHNAME PREVIOUS PREVIOUS-TIME PREVIOUS-PRIMARY
+FOUNDP is true when a system was found,
+either a new unregistered one or a previously registered one.
+FOUND-SYSTEM when not null is a SYSTEM object that may be REGISTER-SYSTEM'ed.
+PATHNAME when not null is a path from which to load the system,
+either associated with FOUND-SYSTEM, or with the PREVIOUS system.
+PREVIOUS when not null is a previously loaded SYSTEM object of same name.
+PREVIOUS-TIME when not null is the time at which the PREVIOUS system was loaded.
+PREVIOUS-PRIMARY when not null is the primary system for the PREVIOUS system."
+    (with-asdf-session () ;; NB: We don't cache the results. We once used to, but it wasn't useful,
+      ;; and keeping a negative cache was a bug (see lp#1335323), which required
+      ;; explicit invalidation in clear-system and find-system (when unsucccessful).
+      (let* ((name (coerce-name name))
+             (previous (registered-system name)) ; load from disk if absent or newer on disk
+             (previous-primary-name (and previous (primary-system-name previous)))
+             (previous-primary-system (and previous-primary-name
+                                           (registered-system previous-primary-name)))
+             (previous-time (and previous-primary-system
+                                 (component-operation-time 'define-op previous-primary-system)))
+             (found (search-for-system-definition name))
+             (found-system (and (typep found 'system) found))
+             (pathname (ensure-pathname
+                        (or (and (typep found '(or pathname string)) (pathname found))
+                            (system-source-file found-system)
+                            (system-source-file previous))
+                        :want-absolute t :resolve-symlinks *resolve-symlinks*))
+             (foundp (and (or found-system pathname previous) t)))
+        (check-type found (or null pathname system))
+        (unless (check-not-old-asdf-system name pathname)
+          (check-type previous system) ;; asdf is preloaded, so there should be a previous one.
+          (setf found-system nil pathname nil))
+        (values foundp found-system pathname previous previous-time previous-primary-system))))
+
+  ;; TODO: make a prepare-define-op node for this
+  ;; so we can properly cache the answer rather than recompute it.
+  (defun definition-dependencies-up-to-date-p (system)
+    (check-type system system)
+    (or (not (primary-system-p system))
+        (handler-case
+            (loop :with plan = (make-instance *plan-class*)
+              :for action :in (definition-dependency-list system)
+              :always (action-up-to-date-p
+                       plan (action-operation action) (action-component action))
+              :finally
+              (let ((o (make-operation 'define-op)))
+                (multiple-value-bind (stamp done-p)
+                    (compute-action-stamp plan o system)
+                  (return (and (timestamp<= stamp (component-operation-time o system))
+                               done-p)))))
+          (system-out-of-date () nil))))
+
+  ;; Main method for find-system: first, make sure the computation is memoized in a session cache.
+  ;; Unless the system is immutable, use locate-system to find the primary system;
+  ;; reconcile the finding (if any) with any previous definition (in a previous session,
+  ;; preloaded, with a previous configuration, or before filesystem changes), and
+  ;; load a found .asd if appropriate. Finally, update registration table and return results.
+  (defmethod find-system ((name string) &optional (error-p t))
+    (nest
+     (with-asdf-session (:key `(find-system ,name)))
+     (let ((name-primary-p (primary-system-p name)))
+       (unless name-primary-p (find-system (primary-system-name name) nil)))
+     (or (and *immutable-systems* (gethash name *immutable-systems*) (registered-system name)))
+     (multiple-value-bind (foundp found-system pathname previous previous-time previous-primary)
+         (locate-system name)
+       (assert (eq foundp (and (or found-system pathname previous) t))))
+     (let ((previous-pathname (system-source-file previous))
+           (system (or previous found-system)))
+       (when (and found-system (not previous))
+         (register-system found-system))
+       (when (and system pathname)
+         (setf (system-source-file system) pathname))
+       (if-let ((stamp (get-file-stamp pathname)))
+         (let ((up-to-date-p
+                (and previous previous-primary
+                     (or (pathname-equal pathname previous-pathname)
+                         (and pathname previous-pathname
+                              (pathname-equal
+                               (physicalize-pathname pathname)
+                               (physicalize-pathname previous-pathname))))
+                     (timestamp<= stamp previous-time)
+                     ;; Check that all previous definition-dependencies are up-to-date,
+                     ;; traversing them without triggering the adding of nodes to the plan.
+                     ;; TODO: actually have a prepare-define-op, extract its timestamp,
+                     ;; and check that it is less than the stamp of the previous define-op ?
+                     (definition-dependencies-up-to-date-p previous-primary))))
+           (unless up-to-date-p
+             (restart-case
+                 (signal 'system-out-of-date :name name)
+               (continue () :report "continue"))
+             (load-asd pathname :name name)))))
+     ;; Try again after having loaded from disk if needed
+     (or (registered-system name)
+         (when error-p (error 'missing-component :requires name)))))
+
+  ;; Resolved forward reference for asdf/system-registry.
+  (defun mark-component-preloaded (component)
+    "Mark a component as preloaded."
+    (let ((component (find-component component nil :registered t)))
+      ;; Recurse to children, so asdf/plan will hopefully be happy.
+      (map () 'mark-component-preloaded (component-children component))
+      ;; Mark the timestamps of the common lisp-action operations as 0.
+      (let ((cot (component-operation-times component)))
+        (dolist (o `(,@(when (primary-system-p component) '(define-op))
+                       prepare-op compile-op load-op))
+          (setf (gethash (make-operation o) cot) 0))))))
+;;;; -------------------------------------------------------------------------
+;;;; Defsystem
+
+(uiop/package:define-package :asdf/parse-defsystem
+  (:recycle :asdf/parse-defsystem :asdf/defsystem :asdf)
+  (:nicknames :asdf/defsystem) ;; previous name, to be compatible with, in case anyone cares
+  (:use :uiop/common-lisp :asdf/driver :asdf/upgrade
+   :asdf/session :asdf/component :asdf/system :asdf/system-registry
+   :asdf/find-component :asdf/action :asdf/lisp-action :asdf/operate)
+  (:import-from :asdf/system #:depends-on #:weakly-depends-on)
+  ;; these needed for record-additional-system-input-file
+  (:import-from :asdf/operation #:make-operation)
+  (:import-from :asdf/component #:%additional-input-files)
+  (:import-from :asdf/find-system #:define-op)
+  (:export
+   #:defsystem #:register-system-definition
+   #:*default-component-class*
+   #:determine-system-directory #:parse-component-form
+   #:non-toplevel-system #:non-system-system #:bad-system-name
+   #:*known-systems-with-bad-secondary-system-names*
+   #:known-system-with-bad-secondary-system-names-p
+   #:sysdef-error-component #:check-component-input
+   #:explain
+   ;; for extending the component types
+   #:compute-component-children
+   #:class-for-type))
+(in-package :asdf/parse-defsystem)
+
+;;; Pathname
+(with-upgradability ()
+  (defun determine-system-directory (pathname)
+    ;; The defsystem macro calls this function to determine the pathname of a system as follows:
+    ;; 1. If the pathname argument is an pathname object (NOT a namestring),
+    ;;    that is already an absolute pathname, return it.
+    ;; 2. Otherwise, the directory containing the LOAD-PATHNAME
+    ;;    is considered (as deduced from e.g. *LOAD-PATHNAME*), and
+    ;;    if it is indeed available and an absolute pathname, then
+    ;;    the PATHNAME argument is normalized to a relative pathname
+    ;;    as per PARSE-UNIX-NAMESTRING (with ENSURE-DIRECTORY T)
+    ;;    and merged into that DIRECTORY as per SUBPATHNAME.
+    ;;    Note: avoid *COMPILE-FILE-PATHNAME* because the .asd is loaded as source,
+    ;;    but may be from within the EVAL-WHEN of a file compilation.
+    ;; If no absolute pathname was found, we return NIL.
+    (check-type pathname (or null string pathname))
+    (pathname-directory-pathname
+     (resolve-symlinks*
+      (ensure-absolute-pathname
+       (parse-unix-namestring pathname :type :directory)
+       #'(lambda () (ensure-absolute-pathname
+                     (load-pathname) 'get-pathname-defaults nil))
+       nil)))))
+
+
+(when-upgrading (:version "3.3.4.17")
+  ;; This turned into a generic function in 3.3.4.17
+  (fmakunbound 'class-for-type))
+
+;;; Component class
+(with-upgradability ()
+  ;; What :file gets interpreted as, unless overridden by a :default-component-class
+  (defvar *default-component-class* 'cl-source-file)
+
+  (defgeneric class-for-type (parent type-designator)
+    (:documentation
+     "Return a CLASS object to be used to instantiate components specified by TYPE-DESIGNATOR in the context of PARENT."))
+
+  (defmethod class-for-type ((parent null) type)
+    "If the PARENT is NIL, then TYPE must designate a subclass of SYSTEM."
+    (or (coerce-class type :package :asdf/interface :super 'system :error nil)
+        (sysdef-error "don't recognize component type ~S in the context of no parent" type)))
+
+  (defmethod class-for-type ((parent parent-component) type)
+    (or (coerce-class type :package :asdf/interface :super 'component :error nil)
+        (and (eq type :file)
+             (coerce-class
+              (or (loop :for p = parent :then (component-parent p) :while p
+                          :thereis (module-default-component-class p))
+                  *default-component-class*)
+              :package :asdf/interface :super 'component :error nil))
+        (sysdef-error "don't recognize component type ~S" type))))
+
+
+;;; Check inputs
+(with-upgradability ()
+  (define-condition non-system-system (system-definition-error)
+    ((name :initarg :name :reader non-system-system-name)
+     (class-name :initarg :class-name :reader non-system-system-class-name))
+    (:report (lambda (c s)
+               (format s (compatfmt "~@<Error while defining system ~S: class ~S isn't a subclass of ~S~@:>")
+                       (non-system-system-name c) (non-system-system-class-name c) 'system))))
+
+  (define-condition non-toplevel-system (system-definition-error)
+    ((parent :initarg :parent :reader non-toplevel-system-parent)
+     (name :initarg :name :reader non-toplevel-system-name))
+    (:report (lambda (c s)
+               (format s (compatfmt "~@<Error while defining system: component ~S claims to have a system ~S as a child~@:>")
+                       (non-toplevel-system-parent c) (non-toplevel-system-name c)))))
+
+  (define-condition bad-system-name (warning)
+    ((name :initarg :name :reader component-name)
+     (source-file :initarg :source-file :reader system-source-file))
+    (:report (lambda (c s)
+               (let* ((file (system-source-file c))
+                      (name (component-name c))
+                      (asd (pathname-name file)))
+                 (format s (compatfmt "~@<System definition file ~S contains definition for system ~S. ~
+Please only define ~S and secondary systems with a name starting with ~S (e.g. ~S) in that file.~@:>")
+                       file name asd (strcat asd "/") (strcat asd "/test"))))))
+
+  (defun sysdef-error-component (msg type name value)
+    (sysdef-error (strcat msg (compatfmt "~&~@<The value specified for ~(~A~) ~A is ~S~@:>"))
+                  type name value))
+
+  (defun check-component-input (type name weakly-depends-on
+                                depends-on components)
+    "A partial test of the values of a component."
+    (unless (listp depends-on)
+      (sysdef-error-component ":depends-on must be a list."
+                              type name depends-on))
+    (unless (listp weakly-depends-on)
+      (sysdef-error-component ":weakly-depends-on must be a list."
+                              type name weakly-depends-on))
+    (unless (listp components)
+      (sysdef-error-component ":components must be NIL or a list of components."
+                              type name components)))
+
+
+  (defun record-additional-system-input-file (pathname component parent)
+    (let* ((record-on (if parent
+                          (loop :with retval
+                                :for par = parent :then (component-parent par)
+                                :while par
+                                :do (setf retval par)
+                                :finally (return retval))
+                          component))
+           (comp (if (typep record-on 'component)
+                     record-on
+                     ;; at this point there will be no parent for RECORD-ON
+                     (find-component record-on nil)))
+           (op (make-operation 'define-op))
+           (cell (or (assoc op (%additional-input-files comp))
+                       (let ((new-cell (list op)))
+                         (push new-cell (%additional-input-files comp))
+                         new-cell))))
+      (pushnew pathname (cdr cell) :test 'pathname-equal)
+      (values)))
+
+  ;; Given a form used as :version specification, in the context of a system definition
+  ;; in a file at PATHNAME, for given COMPONENT with given PARENT, normalize the form
+  ;; to an acceptable ASDF-format version.
+  (fmakunbound 'normalize-version) ;; signature changed between 2.27 and 2.31
+  (defun normalize-version (form &key pathname component parent)
+    (labels ((invalid (&optional (continuation "using NIL instead"))
+               (warn (compatfmt "~@<Invalid :version specifier ~S~@[ for component ~S~]~@[ in ~S~]~@[ from file ~S~]~@[, ~A~]~@:>")
+                     form component parent pathname continuation))
+             (invalid-parse (control &rest args)
+               (unless (if-let (target (find-component parent component)) (builtin-system-p target))
+                 (apply 'warn control args)
+                 (invalid))))
+      (if-let (v (typecase form
+                   ((or string null) form)
+                   (real
+                    (invalid "Substituting a string")
+                    (format nil "~D" form)) ;; 1.0 becomes "1.0"
+                   (cons
+                    (case (first form)
+                      ((:read-file-form)
+                       (destructuring-bind (subpath &key (at 0)) (rest form)
+                         (let ((path (subpathname pathname subpath)))
+                           (record-additional-system-input-file path component parent)
+                           (safe-read-file-form path
+                                                :at at :package :asdf-user))))
+                      ((:read-file-line)
+                       (destructuring-bind (subpath &key (at 0)) (rest form)
+                         (let ((path (subpathname pathname subpath)))
+                           (record-additional-system-input-file path component parent)
+                           (safe-read-file-line (subpathname pathname subpath)
+                                                :at at))))
+                      (otherwise
+                       (invalid))))
+                   (t
+                    (invalid))))
+        (if-let (pv (parse-version v #'invalid-parse))
+          (unparse-version pv)
+          (invalid))))))
+
+
+;;; "inline methods"
+(with-upgradability ()
+  (defparameter* +asdf-methods+
+      '(perform-with-restarts perform explain output-files operation-done-p))
+
+  (defun %remove-component-inline-methods (component)
+    (dolist (name +asdf-methods+)
+      (map ()
+           ;; this is inefficient as most of the stored
+           ;; methods will not be for this particular gf
+           ;; But this is hardly performance-critical
+           #'(lambda (m)
+               (remove-method (symbol-function name) m))
+           (component-inline-methods component)))
+    (component-inline-methods component) nil)
+
+  (defparameter *standard-method-combination-qualifiers*
+    '(:around :before :after))
+
+;;; Find inline method definitions of the form
+;;;
+;;;   :perform (test-op :before (operation component) ...)
+;;;
+;;; in REST (which is the plist of all DEFSYSTEM initargs) and define the specified methods.
+  (defun %define-component-inline-methods (ret rest)
+    ;; find key-value pairs that look like inline method definitions in REST. For each identified
+    ;; definition, parse it and, if it is well-formed, define the method.
+    (loop :for (key value) :on rest :by #'cddr
+          :for name = (and (keywordp key) (find key +asdf-methods+ :test 'string=))
+          :when name :do
+            ;; parse VALUE as an inline method definition of the form
+            ;;
+            ;;   (OPERATION-NAME [QUALIFIER] (OPERATION-PARAMETER COMPONENT-PARAMETER) &rest BODY)
+            (destructuring-bind (operation-name &rest rest) value
+              (let ((qualifiers '()))
+                ;; ensure that OPERATION-NAME is a symbol.
+                (unless (and (symbolp operation-name) (not (null operation-name)))
+                  (sysdef-error "Ill-formed inline method: ~S. The first element is not a symbol ~
+                              designating an operation but ~S."
+                                value operation-name))
+                ;; ensure that REST starts with either a cons (potential lambda list, further checked
+                ;; below) or a qualifier accepted by the standard method combination. Everything else
+                ;; is ill-formed. In case of a valid qualifier, pop it from REST so REST now definitely
+                ;; has to start with the lambda list.
+                (cond
+                  ((consp (car rest)))
+                  ((not (member (car rest)
+                                *standard-method-combination-qualifiers*))
+                   (sysdef-error "Ill-formed inline method: ~S. Only a single of the standard ~
+                               qualifiers ~{~S~^ ~} is allowed, not ~S."
+                                 value *standard-method-combination-qualifiers* (car rest)))
+                  (t
+                   (setf qualifiers (list (pop rest)))))
+                ;; REST must start with a two-element lambda list.
+                (unless (and (listp (car rest))
+                             (length=n-p (car rest) 2)
+                             (null (cddar rest)))
+                  (sysdef-error "Ill-formed inline method: ~S. The operation name ~S is not followed by ~
+                              a lambda-list of the form (OPERATION COMPONENT) and a method body."
+                                value operation-name))
+                ;; define the method.
+                (destructuring-bind ((o c) &rest body) rest
+                  (pushnew
+                   (eval `(defmethod ,name ,@qualifiers ((,o ,operation-name) (,c (eql ,ret))) ,@body))
+                   (component-inline-methods ret)))))))
+
+  (defun %refresh-component-inline-methods (component rest)
+    ;; clear methods, then add the new ones
+    (%remove-component-inline-methods component)
+    (%define-component-inline-methods component rest)))
+
+
+;;; Main parsing function
+(with-upgradability ()
+  (defun parse-dependency-def (dd)
+    (if (listp dd)
+        (case (first dd)
+          (:feature
+           (unless (= (length dd) 3)
+             (sysdef-error "Ill-formed feature dependency: ~s" dd))
+           (let ((embedded (parse-dependency-def (third dd))))
+             `(:feature ,(second dd) ,embedded)))
+          (feature
+           (sysdef-error "`feature' has been removed from the dependency spec language of ASDF. Use :feature instead in ~s." dd))
+          (:require
+           (unless (= (length dd) 2)
+             (sysdef-error "Ill-formed require dependency: ~s" dd))
+           dd)
+          (:version
+           (unless (= (length dd) 3)
+             (sysdef-error "Ill-formed version dependency: ~s" dd))
+           `(:version ,(coerce-name (second dd)) ,(third dd)))
+          (otherwise (sysdef-error "Ill-formed dependency: ~s" dd)))
+      (coerce-name dd)))
+
+  (defun parse-dependency-defs (dd-list)
+    "Parse the dependency defs in DD-LIST into canonical form by translating all
+system names contained using COERCE-NAME. Return the result."
+    (mapcar 'parse-dependency-def dd-list))
+
+  (defgeneric compute-component-children (component components serial-p)
+    (:documentation
+     "Return a list of children for COMPONENT.
+
+COMPONENTS is a list of the explicitly defined children descriptions.
+
+SERIAL-P is non-NIL if each child in COMPONENTS should depend on the previous
+children."))
+
+  (defun stable-union (s1 s2 &key (test #'eql) (key 'identity))
+   (append s1
+     (remove-if #'(lambda (e2) (member (funcall key e2) (funcall key s1) :test test)) s2)))
+
+  (defun parse-component-form (parent options &key previous-serial-components)
+    (destructuring-bind
+        (type name &rest rest &key
+                                (builtin-system-p () bspp)
+                                ;; the following list of keywords is reproduced below in the
+                                ;; remove-plist-keys form.  important to keep them in sync
+                                components pathname perform explain output-files operation-done-p
+                                weakly-depends-on depends-on serial
+                                do-first if-component-dep-fails version
+                                ;; list ends
+         &allow-other-keys) options
+      (declare (ignore perform explain output-files operation-done-p builtin-system-p))
+      (check-component-input type name weakly-depends-on depends-on components)
+      (when (and parent
+                 (find-component parent name)
+                 (not ;; ignore the same object when rereading the defsystem
+                  (typep (find-component parent name)
+                         (class-for-type parent type))))
+        (error 'duplicate-names :name name))
+      (when do-first (error "DO-FIRST is not supported anymore as of ASDF 3"))
+      (let* ((name (coerce-name name))
+             (args `(:name ,name
+                     :pathname ,pathname
+                     ,@(when parent `(:parent ,parent))
+                     ,@(remove-plist-keys
+                        '(:components :pathname :if-component-dep-fails :version
+                          :perform :explain :output-files :operation-done-p
+                          :weakly-depends-on :depends-on :serial)
+                        rest)))
+             (component (find-component parent name))
+             (class (class-for-type parent type)))
+        (when (and parent (subtypep class 'system))
+          (error 'non-toplevel-system :parent parent :name name))
+        (if component ; preserve identity
+            (apply 'reinitialize-instance component args)
+            (setf component (apply 'make-instance class args)))
+        (component-pathname component) ; eagerly compute the absolute pathname
+        (when (typep component 'system)
+          ;; cache information for introspection
+          (setf (slot-value component 'depends-on)
+                (parse-dependency-defs depends-on)
+                (slot-value component 'weakly-depends-on)
+                ;; these must be a list of systems, cannot be features or versioned systems
+                (mapcar 'coerce-name weakly-depends-on)))
+        (let ((sysfile (system-source-file (component-system component)))) ;; requires the previous
+          (when (and (typep component 'system) (not bspp))
+            (setf (builtin-system-p component) (lisp-implementation-pathname-p sysfile)))
+          (setf version (normalize-version version :component name :parent parent :pathname sysfile)))
+        ;; Don't use the accessor: kluge to avoid upgrade issue on CCL 1.8.
+        ;; A better fix is required.
+        (setf (slot-value component 'version) version)
+        (when (typep component 'parent-component)
+          (setf (component-children component) (compute-component-children component components serial))
+          (compute-children-by-name component))
+        (when previous-serial-components
+          (setf depends-on (stable-union depends-on previous-serial-components :test #'equal)))
+        (when weakly-depends-on
+          ;; ASDF4: deprecate this feature and remove it.
+          (appendf depends-on
+                   (remove-if (complement #'(lambda (x) (find-system x nil))) weakly-depends-on)))
+        ;; Used by POIU. ASDF4: rename to component-depends-on?
+        (setf (component-sideway-dependencies component) depends-on)
+        (%refresh-component-inline-methods component rest)
+        (when if-component-dep-fails
+          (error "The system definition for ~S uses deprecated ~
+            ASDF option :IF-COMPONENT-DEP-FAILS. ~
+            Starting with ASDF 3, please use :IF-FEATURE instead"
+                 (coerce-name (component-system component))))
+        component)))
+
+  (defmethod compute-component-children ((component parent-component) components serial-p)
+    (loop
+      :with previous-components = nil ; list of strings
+      :for c-form :in components
+      :for c = (parse-component-form component c-form
+                                     :previous-serial-components previous-components)
+      :for name :of-type string = (component-name c)
+      :when serial-p
+        ;; if this is an if-feature component, we need to make a serial link
+        ;; from previous components to following components -- otherwise should
+        ;; the IF-FEATURE component drop out, the chain of serial dependencies will be
+        ;; broken.
+        :unless (component-if-feature c)
+          :do (setf previous-components nil)
+        :end
+        :and
+          :do (push name previous-components)
+      :end
+      :collect c))
+
+  ;; the following are all systems that Stas Boukarev maintains and refuses to fix,
+  ;; hoping instead to make my life miserable. Instead, I just make ASDF ignore them.
+  (defparameter* *known-systems-with-bad-secondary-system-names*
+    (list-to-hash-set '("cl-ppcre" "cl-interpol")))
+  (defun known-system-with-bad-secondary-system-names-p (asd-name)
+    ;; Does .asd file with name ASD-NAME contain known exceptions
+    ;; that should be screened out of checking for BAD-SYSTEM-NAME?
+    (gethash asd-name *known-systems-with-bad-secondary-system-names*))
+
+  (defun register-system-definition
+      (name &rest options &key pathname (class 'system) (source-file () sfp)
+                            defsystem-depends-on &allow-other-keys)
+    ;; The system must be registered before we parse the body,
+    ;; otherwise we recur when trying to find an existing system
+    ;; of the same name to reuse options (e.g. pathname) from.
+    ;; To avoid infinite recursion in cases where you defsystem a system
+    ;; that is registered to a different location to find-system,
+    ;; we also need to remember it in the asdf-cache.
+    (nest
+     (with-asdf-session ())
+     (let* ((name (coerce-name name))
+            (source-file (if sfp source-file (resolve-symlinks* (load-pathname))))))
+     (flet ((fix-case (x) (if (logical-pathname-p source-file) (string-downcase x) x))))
+     (let* ((asd-name (and source-file
+                           (equal "asd" (fix-case (pathname-type source-file)))
+                           (fix-case (pathname-name source-file))))
+            ;; note that PRIMARY-NAME is a *syntactically* primary name
+            (primary-name (primary-system-name name)))
+       (when (and asd-name
+                  (not (equal asd-name primary-name))
+                  (not (known-system-with-bad-secondary-system-names-p asd-name)))
+         (warn (make-condition 'bad-system-name :source-file source-file :name name))))
+     (let* (;; NB: handle defsystem-depends-on BEFORE to create the system object,
+            ;; so that in case it fails, there is no incomplete object polluting the build.
+            (checked-defsystem-depends-on
+             (let* ((dep-forms (parse-dependency-defs defsystem-depends-on))
+                    (deps (loop :for spec :in dep-forms
+                            :when (resolve-dependency-spec nil spec)
+                            :collect :it)))
+               (load-systems* deps)
+               dep-forms))
+            (system (or (find-system-if-being-defined name)
+                        (if-let (registered (registered-system name))
+                          (reset-system-class registered 'undefined-system
+                                              :name name :source-file source-file)
+                          (register-system (make-instance 'undefined-system
+                                                          :name name :source-file source-file)))))
+            (component-options
+             (append
+              (remove-plist-keys '(:defsystem-depends-on :class) options)
+              ;; cache defsystem-depends-on in canonical form
+              (when checked-defsystem-depends-on
+                `(:defsystem-depends-on ,checked-defsystem-depends-on))))
+            (directory (determine-system-directory pathname)))
+       ;; This works hand in hand with asdf/find-system:find-system-if-being-defined:
+       (set-asdf-cache-entry `(find-system ,name) (list system)))
+     ;; We change-class AFTER we loaded the defsystem-depends-on
+     ;; since the class might be defined as part of those.
+     (let ((class (class-for-type nil class)))
+       (unless (subtypep class 'system)
+         (error 'non-system-system :name name :class-name (class-name class)))
+       (unless (eq (type-of system) class)
+         (reset-system-class system class)))
+     (parse-component-form nil (list* :system name :pathname directory component-options))))
+
+  (defmacro defsystem (name &body options)
+    `(apply 'register-system-definition ',name ',options)))
+;;;; -------------------------------------------------------------------------
+;;;; ASDF-Bundle
+
+(uiop/package:define-package :asdf/bundle
+  (:recycle :asdf/bundle :asdf)
+  (:use :uiop/common-lisp :uiop :asdf/upgrade
+   :asdf/component :asdf/system :asdf/operation
+   :asdf/find-component ;; used by ECL
+   :asdf/action :asdf/lisp-action :asdf/plan :asdf/operate :asdf/parse-defsystem)
+  (:export
+   #:bundle-op #:bundle-type #:program-system
+   #:bundle-system #:bundle-pathname-type #:direct-dependency-files
+   #:monolithic-op #:monolithic-bundle-op #:operation-monolithic-p
+   #:basic-compile-bundle-op #:prepare-bundle-op
+   #:compile-bundle-op #:load-bundle-op #:monolithic-compile-bundle-op #:monolithic-load-bundle-op
+   #:lib-op #:monolithic-lib-op
+   #:dll-op #:monolithic-dll-op
+   #:deliver-asd-op #:monolithic-deliver-asd-op
+   #:program-op #:image-op #:compiled-file #:precompiled-system #:prebuilt-system
+   #:user-system-p #:user-system #:trivial-system-p
+   #:prologue-code #:epilogue-code #:static-library))
+(in-package :asdf/bundle)
+
+(with-upgradability ()
+  (defclass bundle-op (operation) ()
+    (:documentation "base class for operations that bundle outputs from multiple components"))
+  (defgeneric bundle-type (bundle-op))
+
+  (defclass monolithic-op (operation) ()
+    (:documentation "A MONOLITHIC operation operates on a system *and all of its
+dependencies*.  So, for example, a monolithic concatenate operation will
+concatenate together a system's components and all of its dependencies, but a
+simple concatenate operation will concatenate only the components of the system
+itself."))
+
+  (defclass monolithic-bundle-op (bundle-op monolithic-op)
+    ;; Old style way of specifying prologue and epilogue on ECL: in the monolithic operation.
+    ;; DEPRECATED. Supported replacement: Define slots on program-system instead.
+    ((prologue-code :initform nil :accessor prologue-code)
+     (epilogue-code :initform nil :accessor epilogue-code))
+    (:documentation "operations that are both monolithic-op and bundle-op"))
+
+  (defclass program-system (system)
+    ;; New style (ASDF3.1) way of specifying prologue and epilogue on ECL: in the system
+    ((prologue-code :initform nil :initarg :prologue-code :reader prologue-code)
+     (epilogue-code :initform nil :initarg :epilogue-code :reader epilogue-code)
+     (no-uiop :initform nil :initarg :no-uiop :reader no-uiop)
+     (prefix-lisp-object-files :initarg :prefix-lisp-object-files
+                               :initform nil :accessor prefix-lisp-object-files)
+     (postfix-lisp-object-files :initarg :postfix-lisp-object-files
+                                :initform nil :accessor postfix-lisp-object-files)
+     (extra-object-files :initarg :extra-object-files
+                         :initform nil :accessor extra-object-files)
+     (extra-build-args :initarg :extra-build-args
+                       :initform nil :accessor extra-build-args)))
+
+  (defmethod prologue-code ((x system)) nil)
+  (defmethod epilogue-code ((x system)) nil)
+  (defmethod no-uiop ((x system)) nil)
+  (defmethod prefix-lisp-object-files ((x system)) nil)
+  (defmethod postfix-lisp-object-files ((x system)) nil)
+  (defmethod extra-object-files ((x system)) nil)
+  (defmethod extra-build-args ((x system)) nil)
+
+  (defclass link-op (bundle-op) ()
+    (:documentation "Abstract operation for linking files together"))
+
+  (defclass gather-operation (bundle-op) ()
+    (:documentation "Abstract operation for gathering many input files from a system"))
+  (defgeneric gather-operation (gather-operation))
+  (defmethod gather-operation ((o gather-operation)) nil)
+  (defgeneric gather-type (gather-operation))
+
+  (defun operation-monolithic-p (op)
+    (typep op 'monolithic-op))
+
+  ;; Dependencies of a gather-op are the actions of the dependent operation
+  ;; for all the (sorted) required components for loading the system.
+  ;; Monolithic operations typically use lib-op as the dependent operation,
+  ;; and all system-level dependencies as required components.
+  ;; Non-monolithic operations typically use compile-op as the dependent operation,
+  ;; and all transitive sub-components as required components (excluding other systems).
+  (defmethod component-depends-on ((o gather-operation) (s system))
+    (let* ((mono (operation-monolithic-p o))
+           (go (make-operation (or (gather-operation o) 'compile-op)))
+           (bundle-p (typep go 'bundle-op))
+           ;; In a non-mono operation, don't recurse to other systems.
+           ;; In a mono operation gathering bundles, don't recurse inside systems.
+           (component-type (if mono (if bundle-p 'system t) '(not system)))
+           ;; In the end, only keep system bundles or non-system bundles, depending.
+           (keep-component (if bundle-p 'system '(not system)))
+           (deps
+            ;; Required-components only looks at the dependencies of an action, excluding the action
+            ;; itself, so it may be safely used by an action recursing on its dependencies (which
+            ;; may or may not be an overdesigned API, since in practice we never use it that way).
+            ;; Therefore, if we use :goal-operation 'load-op :keep-operation 'load-op, which looks
+            ;; cleaner, we will miss the load-op on the requested system itself, which doesn't
+            ;; matter for a regular system, but matters, a lot, for a package-inferred-system.
+            ;; Using load-op as the goal operation and basic-compile-op as the keep-operation works
+            ;; for our needs of gathering all the files we want to include in a bundle.
+            ;; Note that we use basic-compile-op rather than compile-op so it will still work on
+            ;; systems that would somehow load dependencies with load-bundle-op.
+            (required-components
+             s :other-systems mono :component-type component-type :keep-component keep-component
+             :goal-operation 'load-op :keep-operation 'basic-compile-op)))
+      `((,go ,@deps) ,@(call-next-method))))
+
+  ;; Create a single fasl for the entire library
+  (defclass basic-compile-bundle-op (bundle-op basic-compile-op) ()
+    (:documentation "Base class for compiling into a bundle"))
+  (defmethod bundle-type ((o basic-compile-bundle-op)) :fasb)
+  (defmethod gather-type ((o basic-compile-bundle-op))
+    #-(or clasp ecl mkcl) :fasl
+    #+(or clasp ecl mkcl) :object)
+
+  ;; Analog to prepare-op, for load-bundle-op and compile-bundle-op
+  (defclass prepare-bundle-op (sideway-operation)
+    ((sideway-operation
+      :initform #+(or clasp ecl mkcl) 'load-bundle-op #-(or clasp ecl mkcl) 'load-op
+      :allocation :class))
+    (:documentation "Operation class for loading the bundles of a system's dependencies"))
+
+  (defclass lib-op (link-op gather-operation non-propagating-operation) ()
+    (:documentation "Compile the system and produce a linkable static library (.a/.lib)
+for all the linkable object files associated with the system. Compare with DLL-OP.
+
+On most implementations, these object files only include extensions to the runtime
+written in C or another language with a compiler producing linkable object files.
+On CLASP, ECL, MKCL, these object files _also_ include the contents of Lisp files
+themselves. In any case, this operation will produce what you need to further build
+a static runtime for your system, or a dynamic library to load in an existing runtime."))
+  (defmethod bundle-type ((o lib-op)) :lib)
+  (defmethod gather-type ((o lib-op)) :object)
+
+  ;; What works: on ECL, CLASP(?), MKCL, we link the many .o files from the system into the .so;
+  ;; on other implementations, we combine (usually concatenate) the .fasl files into one.
+  (defclass compile-bundle-op (basic-compile-bundle-op selfward-operation gather-operation
+                                                       #+(or clasp ecl mkcl) link-op)
+    ((selfward-operation :initform '(prepare-bundle-op) :allocation :class))
+    (:documentation "This operator is an alternative to COMPILE-OP. Build a system
+and all of its dependencies, but build only a single (\"monolithic\") FASL, instead
+of one per source file, which may be more resource efficient.  That monolithic
+FASL should be loaded with LOAD-BUNDLE-OP, rather than LOAD-OP."))
+
+  (defclass load-bundle-op (basic-load-op selfward-operation)
+    ((selfward-operation :initform '(prepare-bundle-op compile-bundle-op) :allocation :class))
+    (:documentation "This operator is an alternative to LOAD-OP. Build a system
+and all of its dependencies, using COMPILE-BUNDLE-OP. The difference with
+respect to LOAD-OP is that it builds only a single FASL, which may be
+faster and more resource efficient."))
+
+  ;; NB: since the monolithic-op's can't be sideway-operation's,
+  ;; if we wanted lib-op, dll-op, deliver-asd-op to be sideway-operation's,
+  ;; we'd have to have the monolithic-op not inherit from the main op,
+  ;; but instead inherit from a basic-FOO-op as with basic-compile-bundle-op above.
+
+  (defclass dll-op (link-op gather-operation non-propagating-operation) ()
+    (:documentation "Compile the system and produce a dynamic loadable library (.so/.dll)
+for all the linkable object files associated with the system. Compare with LIB-OP."))
+  (defmethod bundle-type ((o dll-op)) :dll)
+  (defmethod gather-type ((o dll-op)) :object)
+
+  (defclass deliver-asd-op (basic-compile-op selfward-operation)
+    ((selfward-operation
+      ;; TODO: implement link-op on all implementations, and make that
+      ;; '(compile-bundle-op lib-op #-(or clasp ecl mkcl) dll-op)
+      :initform '(compile-bundle-op #+(or clasp ecl mkcl) lib-op)
+      :allocation :class))
+    (:documentation "produce an asd file for delivering the system as a single fasl"))
+
+
+  (defclass monolithic-deliver-asd-op (deliver-asd-op monolithic-bundle-op)
+    ((selfward-operation
+      ;; TODO: implement link-op on all implementations, and make that
+      ;; '(monolithic-compile-bundle-op monolithic-lib-op #-(or clasp ecl mkcl) monolithic-dll-op)
+      :initform '(monolithic-compile-bundle-op #+(or clasp ecl mkcl) monolithic-lib-op)
+      :allocation :class))
+    (:documentation "produce fasl and asd files for combined system and dependencies."))
+
+  (defclass monolithic-compile-bundle-op
+      (basic-compile-bundle-op monolithic-bundle-op
+       #+(or clasp ecl mkcl) link-op gather-operation non-propagating-operation)
+    ()
+    (:documentation "Create a single fasl for the system and its dependencies."))
+
+  (defclass monolithic-load-bundle-op (load-bundle-op monolithic-bundle-op)
+    ((selfward-operation :initform 'monolithic-compile-bundle-op :allocation :class))
+    (:documentation "Load a single fasl for the system and its dependencies."))
+
+  (defclass monolithic-lib-op (lib-op monolithic-bundle-op non-propagating-operation) ()
+    (:documentation "Compile the system and produce a linkable static library (.a/.lib)
+for all the linkable object files associated with the system or its dependencies. See LIB-OP."))
+
+  (defclass monolithic-dll-op (dll-op monolithic-bundle-op non-propagating-operation) ()
+    (:documentation "Compile the system and produce a dynamic loadable library (.so/.dll)
+for all the linkable object files associated with the system or its dependencies. See LIB-OP"))
+
+  (defclass image-op (monolithic-bundle-op selfward-operation
+                      #+(or clasp ecl mkcl) link-op #+(or clasp ecl mkcl) gather-operation)
+    ((selfward-operation :initform '(#-(or clasp ecl mkcl) load-op) :allocation :class))
+    (:documentation "create an image file from the system and its dependencies"))
+  (defmethod bundle-type ((o image-op)) :image)
+  #+(or clasp ecl mkcl) (defmethod gather-operation ((o image-op)) 'lib-op)
+  #+(or clasp ecl mkcl) (defmethod gather-type ((o image-op)) :static-library)
+
+  (defclass program-op (image-op) ()
+    (:documentation "create an executable file from the system and its dependencies"))
+  (defmethod bundle-type ((o program-op)) :program)
+
+  ;; From the ASDF-internal bundle-type identifier, get a filesystem-usable pathname type.
+  (defun bundle-pathname-type (bundle-type)
+    (etypecase bundle-type
+      ((or null string) ;; pass through nil or string literal
+       bundle-type)
+      ((eql :no-output-file) ;; marker for a bundle-type that has NO output file
+       (error "No output file, therefore no pathname type"))
+      ((eql :fasl) ;; the type of a fasl
+       (compile-file-type)) ; on image-based platforms, used as input and output
+      ((eql :fasb) ;; the type of a fasl
+       #-(or clasp ecl mkcl) (compile-file-type) ; on image-based platforms, used as input and output
+       #+(or ecl mkcl) "fasb"
+       #+clasp "fasp") ; on C-linking platforms, only used as output for system bundles
+      ((member :image)
+       #+allegro "dxl"
+       #+(and clisp os-windows) "exe"
+       #-(or allegro (and clisp os-windows)) "image")
+      ;; NB: on CLASP and ECL these implementations, we better agree with
+      ;; (compile-file-type :type bundle-type))
+      ((eql :object) ;; the type of a linkable object file
+       (os-cond ((os-unix-p)
+                 #+clasp "fasp" ;(core:build-extension cmp:*default-object-type*)
+                 #-clasp "o")
+                ((os-windows-p) (if (featurep '(:or :mingw32 :mingw64)) "o" "obj"))))
+      ((member :lib :static-library) ;; the type of a linkable library
+       (os-cond ((os-unix-p) "a")
+                ((os-windows-p) (if (featurep '(:or :mingw32 :mingw64)) "a" "lib"))))
+      ((member :dll :shared-library) ;; the type of a shared library
+       (os-cond ((os-macosx-p) "dylib") ((os-unix-p) "so") ((os-windows-p) "dll")))
+      ((eql :program) ;; the type of an executable program
+       (os-cond ((os-unix-p) nil) ((os-windows-p) "exe")))))
+
+  ;; Compute the output-files for a given bundle action
+  (defun bundle-output-files (o c)
+    (let ((bundle-type (bundle-type o)))
+      (unless (or (eq bundle-type :no-output-file) ;; NIL already means something regarding type.
+                  (and (null (input-files o c)) (not (member bundle-type '(:image :program)))))
+        (let ((name (or (component-build-pathname c)
+                        (let ((suffix
+                               (unless (typep o 'program-op)
+                                 ;; "." is no good separator for Logical Pathnames, so we use "--"
+                                 (if (operation-monolithic-p o)
+                                     "--all-systems"
+                                     ;; These use a different type .fasb or .a instead of .fasl
+                                     #-(or clasp ecl mkcl) "--system"))))
+                          (format nil "~A~@[~A~]" (coerce-filename (component-name c)) suffix))))
+              (type (bundle-pathname-type bundle-type)))
+          (values (list (subpathname (component-pathname c) name :type type))
+                  (eq (class-of o) (coerce-class (component-build-operation c)
+                                                 :package :asdf/interface
+                                                 :super 'operation
+                                                 :error nil)))))))
+
+  (defmethod output-files ((o bundle-op) (c system))
+    (bundle-output-files o c))
+
+  #-(or clasp ecl mkcl)
+  (progn
+    (defmethod perform ((o image-op) (c system))
+      (dump-image (output-file o c) :executable (typep o 'program-op)))
+    (defmethod perform :before ((o program-op) (c system))
+      (setf *image-entry-point* (ensure-function (component-entry-point c)))))
+
+  (defclass compiled-file (file-component)
+    ((type :initform #-(or clasp ecl mkcl) (compile-file-type) #+(or clasp ecl mkcl) "fasb"))
+    (:documentation "Class for a file that is already compiled,
+e.g. as part of the implementation, of an outer build system that calls into ASDF,
+or of opaque libraries shipped along the source code."))
+
+  (defclass precompiled-system (system)
+    ((build-pathname :initarg :fasb :initarg :fasl))
+    (:documentation "Class For a system that is delivered as a precompiled fasl"))
+
+  (defclass prebuilt-system (system)
+    ((build-pathname :initarg :static-library :initarg :lib
+                     :accessor prebuilt-system-static-library))
+    (:documentation "Class for a system delivered with a linkable static library (.a/.lib)")))
+
+
+;;;
+;;; BUNDLE-OP
+;;;
+;;; This operation takes all components from one or more systems and
+;;; creates a single output file, which may be
+;;; a FASL, a statically linked library, a shared library, etc.
+;;; The different targets are defined by specialization.
+;;;
+(when-upgrading (:version "3.2.0")
+  ;; Cancel any previously defined method
+  (defmethod initialize-instance :after ((instance bundle-op) &rest initargs &key &allow-other-keys)
+    (declare (ignore initargs))))
+
+(with-upgradability ()
+  (defgeneric trivial-system-p (component))
+
+  (defun user-system-p (s)
+    (and (typep s 'system)
+         (not (builtin-system-p s))
+         (not (trivial-system-p s)))))
+
+(eval-when (#-lispworks :compile-toplevel :load-toplevel :execute)
+  (deftype user-system () '(and system (satisfies user-system-p))))
+
+;;;
+;;; First we handle monolithic bundles.
+;;; These are standalone systems which contain everything,
+;;; including other ASDF systems required by the current one.
+;;; A PROGRAM is always monolithic.
+;;;
+;;; MONOLITHIC SHARED LIBRARIES, PROGRAMS, FASL
+;;;
+(with-upgradability ()
+  (defun direct-dependency-files (o c &key (test 'identity) (key 'output-files) &allow-other-keys)
+    ;; This function selects output files from direct dependencies;
+    ;; your component-depends-on method must gather the correct dependencies in the correct order.
+    (while-collecting (collect)
+      (map-direct-dependencies
+       o c #'(lambda (sub-o sub-c)
+               (loop :for f :in (funcall key sub-o sub-c)
+                 :when (funcall test f) :do (collect f))))))
+
+  (defun pathname-type-equal-function (type)
+    #'(lambda (p) (equalp (pathname-type p) type)))
+
+  (defmethod input-files ((o gather-operation) (c system))
+    (unless (eq (bundle-type o) :no-output-file)
+      (direct-dependency-files
+       o c :key 'output-files
+           :test (pathname-type-equal-function (bundle-pathname-type (gather-type o))))))
+
+  ;; Find the operation that produces a given bundle-type
+  (defun select-bundle-operation (type &optional monolithic)
+    (ecase type
+      ((:dll :shared-library)
+       (if monolithic 'monolithic-dll-op 'dll-op))
+      ((:lib :static-library)
+       (if monolithic 'monolithic-lib-op 'lib-op))
+      ((:fasb)
+       (if monolithic 'monolithic-compile-bundle-op 'compile-bundle-op))
+      ((:image)
+       'image-op)
+      ((:program)
+       'program-op))))
+
+;;;
+;;; LOAD-BUNDLE-OP
+;;;
+;;; This is like ASDF's LOAD-OP, but using bundle fasl files.
+;;;
+(with-upgradability ()
+  (defmethod component-depends-on ((o load-bundle-op) (c system))
+    `((,o ,@(component-sideway-dependencies c))
+      (,(if (user-system-p c) 'compile-bundle-op 'load-op) ,c)
+      ,@(call-next-method)))
+
+  (defmethod input-files ((o load-bundle-op) (c system))
+    (when (user-system-p c)
+      (output-files (find-operation o 'compile-bundle-op) c)))
+
+  (defmethod perform ((o load-bundle-op) (c system))
+    (when (input-files o c)
+      (perform-lisp-load-fasl o c)))
+
+  (defmethod mark-operation-done :after ((o load-bundle-op) (c system))
+    (mark-operation-done (find-operation o 'load-op) c)))
+
+;;;
+;;; PRECOMPILED FILES
+;;;
+;;; This component can be used to distribute ASDF systems in precompiled form.
+;;; Only useful when the dependencies have also been precompiled.
+;;;
+(with-upgradability ()
+  (defmethod trivial-system-p ((s system))
+    (every #'(lambda (c) (typep c 'compiled-file)) (component-children s)))
+
+  (defmethod input-files ((o operation) (c compiled-file))
+    (list (component-pathname c)))
+  (defmethod perform ((o load-op) (c compiled-file))
+    (perform-lisp-load-fasl o c))
+  (defmethod perform ((o load-source-op) (c compiled-file))
+    (perform (find-operation o 'load-op) c))
+  (defmethod perform ((o operation) (c compiled-file))
+    nil))
+
+;;;
+;;; Pre-built systems
+;;;
+(with-upgradability ()
+  (defmethod trivial-system-p ((s prebuilt-system))
+    t)
+
+  (defmethod perform ((o link-op) (c prebuilt-system))
+    nil)
+
+  (defmethod perform ((o basic-compile-bundle-op) (c prebuilt-system))
+    nil)
+
+  (defmethod perform ((o lib-op) (c prebuilt-system))
+    nil)
+
+  (defmethod perform ((o dll-op) (c prebuilt-system))
+    nil)
+
+  (defmethod component-depends-on ((o gather-operation) (c prebuilt-system))
+    nil)
+
+  (defmethod output-files ((o lib-op) (c prebuilt-system))
+    (values (list (prebuilt-system-static-library c)) t)))
+
+
+;;;
+;;; PREBUILT SYSTEM CREATOR
+;;;
+(with-upgradability ()
+  (defmethod output-files ((o deliver-asd-op) (s system))
+    (list (make-pathname :name (coerce-filename (component-name s)) :type "asd"
+                         :defaults (component-pathname s))))
+
+  ;; because of name collisions between the output files of different
+  ;; subclasses of DELIVER-ASD-OP, we cannot trust the file system to
+  ;; tell us if the output file is up-to-date, so just treat the
+  ;; operation as never being done.
+  (defmethod operation-done-p ((o deliver-asd-op) (s system))
+    (declare (ignorable o s))
+    nil)
+
+  (defun space-for-crlf (s)
+    (substitute-if #\space #'(lambda (x) (find x +crlf+)) s))
+
+  (defmethod perform ((o deliver-asd-op) (s system))
+    "Write an ASDF system definition for loading S as a delivered system."
+    (let* ((inputs (input-files o s))
+           (fasl (first inputs))
+           (library (second inputs))
+           (asd (output-file o s))
+           (name (if (and fasl asd) (pathname-name asd) (return-from perform)))
+           (version (component-version s))
+           (dependencies
+             (if (operation-monolithic-p o)
+                 ;; We want only dependencies, and we use basic-load-op rather than load-op so that
+                 ;; this will keep working on systems that load dependencies with load-bundle-op
+                 (remove-if-not 'builtin-system-p
+                                (required-components s :component-type 'system
+                                                       :keep-operation 'basic-load-op))
+                 (while-collecting (x) ;; resolve the sideway-dependencies of s
+                   (map-direct-dependencies
+                    'prepare-op s
+                    #'(lambda (o c)
+                        (when (and (typep o 'load-op) (typep c 'system))
+                          (x c)))))))
+           (depends-on (mapcar 'coerce-name dependencies)))
+      (when (pathname-equal asd (system-source-file s))
+        (cerror "overwrite the asd file"
+                "~/asdf-action:format-action/ is going to overwrite the system definition file ~S ~
+which is probably not what you want; you probably need to tweak your output translations."
+                (cons o s) asd))
+      (with-open-file (s asd :direction :output :if-exists :supersede
+                             :if-does-not-exist :create)
+        (format s ";;; Prebuilt~:[~; monolithic~] ASDF definition for system ~A~%"
+                (operation-monolithic-p o) name)
+        ;; this can cause bugs in cases where one of the functions returns a multi-line
+        ;; string
+        (let ((description-string (format nil ";;; Built for ~A ~A on a ~A/~A ~A"
+                    (lisp-implementation-type)
+                    (lisp-implementation-version)
+                    (software-type)
+                    (machine-type)
+                    (software-version))))
+          ;; ensure the whole thing is on one line
+          (println (space-for-crlf description-string) s))
+        (let ((*package* (find-package :asdf-user)))
+          (pprint `(defsystem ,name
+                     :class prebuilt-system
+                     :version ,version
+                     :depends-on ,depends-on
+                     :components ((:compiled-file ,(pathname-name fasl)))
+                     ,@(when library `(:lib ,(file-namestring library))))
+                  s)
+          (terpri s)))))
+
+  #-(or clasp ecl mkcl)
+  (defmethod perform ((o basic-compile-bundle-op) (c system))
+    (let* ((input-files (input-files o c))
+           (fasl-files (remove (compile-file-type) input-files :key #'pathname-type :test-not #'equalp))
+           (non-fasl-files (remove (compile-file-type) input-files :key #'pathname-type :test #'equalp))
+           (output-files (output-files o c)) ; can't use OUTPUT-FILE fn because possibility it's NIL
+           (output-file (first output-files)))
+      (assert (eq (not input-files) (not output-files)))
+      (when input-files
+        (when non-fasl-files
+          (error "On ~A, asdf/bundle can only bundle FASL files, but these were also produced: ~S"
+                 (implementation-type) non-fasl-files))
+        (when (or (prologue-code c) (epilogue-code c))
+          (error "prologue-code and epilogue-code are not supported on ~A"
+                 (implementation-type)))
+        (with-staging-pathname (output-file)
+          (combine-fasls fasl-files output-file)))))
+
+  (defmethod input-files ((o load-op) (s precompiled-system))
+    (bundle-output-files (find-operation o 'compile-bundle-op) s))
+
+  (defmethod perform ((o load-op) (s precompiled-system))
+    (perform-lisp-load-fasl o s))
+
+  (defmethod component-depends-on ((o load-bundle-op) (s precompiled-system))
+    `((load-op ,s) ,@(call-next-method))))
+
+#| ;; Example use:
+(asdf:defsystem :precompiled-asdf-utils :class asdf::precompiled-system :fasl (asdf:apply-output-translations (asdf:system-relative-pathname :asdf-utils "asdf-utils.system.fasl")))
+(asdf:load-system :precompiled-asdf-utils)
+|#
+
+#+(or clasp ecl mkcl)
+(with-upgradability ()
+  (defun system-module-pathname (module)
+    (let ((name (coerce-name module)))
+      (some
+       'file-exists-p
+       (list
+        #+clasp (compile-file-pathname (make-pathname :name name :defaults "sys:") :output-type :object)
+        #+ecl (compile-file-pathname (make-pathname :name name :defaults "sys:") :type :lib)
+        #+ecl (compile-file-pathname (make-pathname :name (strcat "lib" name) :defaults "sys:") :type :lib)
+        #+ecl (compile-file-pathname (make-pathname :name name :defaults "sys:") :type :object)
+        #+mkcl (make-pathname :name name :type (bundle-pathname-type :lib) :defaults #p"sys:")
+        #+mkcl (make-pathname :name name :type (bundle-pathname-type :lib) :defaults #p"sys:contrib;")))))
+
+  (defun make-prebuilt-system (name &optional (pathname (system-module-pathname name)))
+    "Creates a prebuilt-system if PATHNAME isn't NIL."
+    (when pathname
+      (make-instance 'prebuilt-system
+                     :name (coerce-name name)
+                     :static-library (resolve-symlinks* pathname))))
+
+  (defun linkable-system (x)
+    (or ;; If the system is available as source, use it.
+        (if-let (s (find-system x))
+          (and (output-files 'lib-op s) s))
+        ;; If an ASDF upgrade is available from source, but not a UIOP upgrade to that,
+        ;; then use the asdf/driver system instead of
+        ;; the UIOP that was disabled by check-not-old-asdf-system.
+        (if-let (s (and (equal (coerce-name x) "uiop")
+                        (output-files 'lib-op "asdf")
+                        (find-system "asdf/driver")))
+          (and (output-files 'lib-op s) s))
+        ;; If there was no source upgrade, look for modules provided by the implementation.
+        (if-let (p (system-module-pathname (coerce-name x)))
+          (make-prebuilt-system x p))))
+
+  (defmethod component-depends-on :around ((o image-op) (c system))
+    (let* ((next (call-next-method))
+           (deps (make-hash-table :test 'equal))
+           (linkable (loop :for (do . dcs) :in next :collect
+                       (cons do
+                             (loop :for dc :in dcs
+                               :for dep = (and dc (resolve-dependency-spec c dc))
+                               :when dep
+                               :do (setf (gethash (coerce-name (component-system dep)) deps) t)
+                               :collect (or (and (typep dep 'system) (linkable-system dep)) dep))))))
+        `((lib-op
+           ,@(unless (no-uiop c)
+               (list (linkable-system "cmp")
+                     (unless (or (and (gethash "uiop" deps) (linkable-system "uiop"))
+                                 (and (gethash "asdf" deps) (linkable-system "asdf")))
+                       (or (linkable-system "uiop")
+                           (linkable-system "asdf")
+                           "asdf")))))
+          ,@linkable)))
+
+  (defmethod perform ((o link-op) (c system))
+    (let* ((object-files (input-files o c))
+           (output (output-files o c))
+           (bundle (first output))
+           (programp (typep o 'program-op))
+           (kind (bundle-type o)))
+      (when output
+        (apply 'create-image
+               bundle (append
+                       (when programp (prefix-lisp-object-files c))
+                       object-files
+                       (when programp (postfix-lisp-object-files c)))
+               :kind kind
+               :prologue-code (when programp (prologue-code c))
+               :epilogue-code (when programp (epilogue-code c))
+               :build-args (when programp (extra-build-args c))
+               :extra-object-files (when programp (extra-object-files c))
+               :no-uiop (no-uiop c)
+               (when programp `(:entry-point ,(component-entry-point c))))))))
+;;;; -------------------------------------------------------------------------
+;;;; Concatenate-source
+
+(uiop/package:define-package :asdf/concatenate-source
+  (:recycle :asdf/concatenate-source :asdf)
+  (:use :uiop/common-lisp :uiop :asdf/upgrade
+   :asdf/component :asdf/operation
+   :asdf/system
+   :asdf/action :asdf/lisp-action :asdf/plan :asdf/bundle)
+  (:export
+   #:concatenate-source-op
+   #:load-concatenated-source-op
+   #:compile-concatenated-source-op
+   #:load-compiled-concatenated-source-op
+   #:monolithic-concatenate-source-op
+   #:monolithic-load-concatenated-source-op
+   #:monolithic-compile-concatenated-source-op
+   #:monolithic-load-compiled-concatenated-source-op))
+(in-package :asdf/concatenate-source)
+
+;;;
+;;; Concatenate sources
+;;;
+(with-upgradability ()
+  ;; Base classes for both regular and monolithic concatenate-source operations
+  (defclass basic-concatenate-source-op (bundle-op) ())
+  (defmethod bundle-type ((o basic-concatenate-source-op)) "lisp")
+  (defclass basic-load-concatenated-source-op (basic-load-op selfward-operation) ())
+  (defclass basic-compile-concatenated-source-op (basic-compile-op selfward-operation) ())
+  (defclass basic-load-compiled-concatenated-source-op (basic-load-op selfward-operation) ())
+
+  ;; Regular concatenate-source operations
+  (defclass concatenate-source-op (basic-concatenate-source-op non-propagating-operation) ()
+    (:documentation "Operation to concatenate all sources in a system into a single file"))
+  (defclass load-concatenated-source-op (basic-load-concatenated-source-op)
+    ((selfward-operation :initform '(prepare-op concatenate-source-op) :allocation :class))
+    (:documentation "Operation to load the result of concatenate-source-op as source"))
+  (defclass compile-concatenated-source-op (basic-compile-concatenated-source-op)
+    ((selfward-operation :initform '(prepare-op concatenate-source-op) :allocation :class))
+    (:documentation "Operation to compile the result of concatenate-source-op"))
+  (defclass load-compiled-concatenated-source-op (basic-load-compiled-concatenated-source-op)
+    ((selfward-operation :initform '(prepare-op compile-concatenated-source-op) :allocation :class))
+    (:documentation "Operation to load the result of compile-concatenated-source-op"))
+
+  (defclass monolithic-concatenate-source-op
+      (basic-concatenate-source-op monolithic-bundle-op non-propagating-operation) ()
+    (:documentation "Operation to concatenate all sources in a system and its dependencies
+into a single file"))
+  (defclass monolithic-load-concatenated-source-op (basic-load-concatenated-source-op)
+    ((selfward-operation :initform 'monolithic-concatenate-source-op :allocation :class))
+    (:documentation "Operation to load the result of monolithic-concatenate-source-op as source"))
+  (defclass monolithic-compile-concatenated-source-op (basic-compile-concatenated-source-op)
+    ((selfward-operation :initform 'monolithic-concatenate-source-op :allocation :class))
+    (:documentation "Operation to compile the result of monolithic-concatenate-source-op"))
+  (defclass monolithic-load-compiled-concatenated-source-op
+      (basic-load-compiled-concatenated-source-op)
+    ((selfward-operation :initform 'monolithic-compile-concatenated-source-op :allocation :class))
+    (:documentation "Operation to load the result of monolithic-compile-concatenated-source-op"))
+
+  (defmethod input-files ((operation basic-concatenate-source-op) (s system))
+    (loop :with encoding = (or (component-encoding s) *default-encoding*)
+          :with other-encodings = '()
+          :with around-compile = (around-compile-hook s)
+          :with other-around-compile = '()
+          :for c :in (required-components  ;; see note about similar call to required-components
+                      s :goal-operation 'load-op ;;  in bundle.lisp
+                        :keep-operation 'basic-compile-op
+                        :other-systems (operation-monolithic-p operation))
+          :append
+          (when (typep c 'cl-source-file)
+            (let ((e (component-encoding c)))
+              (unless (or (equal e encoding)
+                          (and (equal e :ASCII) (equal encoding :UTF-8)))
+                (let ((a (assoc e other-encodings)))
+                  (if a (push (component-find-path c) (cdr a))
+                      (push (list e (component-find-path c)) other-encodings)))))
+            (unless (equal around-compile (around-compile-hook c))
+              (push (component-find-path c) other-around-compile))
+            (input-files (make-operation 'compile-op) c)) :into inputs
+          :finally
+             (when other-encodings
+               (warn "~S uses encoding ~A but has sources that use these encodings:~{ ~A~}"
+                     operation encoding
+                     (mapcar #'(lambda (x) (cons (car x) (list (reverse (cdr x)))))
+                             other-encodings)))
+             (when other-around-compile
+               (warn "~S uses around-compile hook ~A but has sources that use these hooks: ~A"
+                     operation around-compile other-around-compile))
+             (return inputs)))
+  (defmethod output-files ((o basic-compile-concatenated-source-op) (s system))
+    (lisp-compilation-output-files o s))
+
+  (defmethod perform ((o basic-concatenate-source-op) (s system))
+    (let* ((ins (input-files o s))
+           (out (output-file o s))
+           (tmp (tmpize-pathname out)))
+      (concatenate-files ins tmp)
+      (rename-file-overwriting-target tmp out)))
+  (defmethod perform ((o basic-load-concatenated-source-op) (s system))
+    (perform-lisp-load-source o s))
+  (defmethod perform ((o basic-compile-concatenated-source-op) (s system))
+    (perform-lisp-compilation o s))
+  (defmethod perform ((o basic-load-compiled-concatenated-source-op) (s system))
+    (perform-lisp-load-fasl o s)))
+
+;;;; -------------------------------------------------------------------------
+;;;; Package systems in the style of quick-build or faslpath
+
+(uiop:define-package :asdf/package-inferred-system
+  (:recycle :asdf/package-inferred-system :asdf/package-system :asdf)
+  (:use :uiop/common-lisp :uiop
+        :asdf/upgrade :asdf/session
+        :asdf/component :asdf/system :asdf/system-registry :asdf/lisp-action
+        :asdf/parse-defsystem)
+  (:export
+   #:package-inferred-system #:sysdef-package-inferred-system-search
+   #:package-system ;; backward compatibility only. To be removed.
+   #:register-system-packages
+   #:*defpackage-forms* #:*package-inferred-systems* #:package-inferred-system-missing-package-error))
+(in-package :asdf/package-inferred-system)
+
+(with-upgradability ()
+  ;; The names of the recognized defpackage forms.
+  (defparameter *defpackage-forms* '(defpackage define-package))
+
+  (defun initial-package-inferred-systems-table ()
+    ;; Mark all existing packages are preloaded.
+    (let ((h (make-hash-table :test 'equal)))
+      (dolist (p (list-all-packages))
+        (dolist (n (package-names p))
+          (setf (gethash n h) t)))
+      h))
+
+  ;; Mapping from package names to systems that provide them.
+  (defvar *package-inferred-systems* (initial-package-inferred-systems-table))
+
+  (defclass package-inferred-system (system)
+    ()
+    (:documentation "Class for primary systems for which secondary systems are automatically
+in the one-file, one-file, one-system style: system names are mapped to files under the primary
+system's system-source-directory, dependencies are inferred from the first defpackage form in
+every such file"))
+
+  ;; DEPRECATED. For backward compatibility only. To be removed in an upcoming release:
+  (defclass package-system (package-inferred-system) ())
+
+  ;; Is a given form recognizable as a defpackage form?
+  (defun defpackage-form-p (form)
+    (and (consp form)
+         (member (car form) *defpackage-forms*)))
+
+  ;; Find the first defpackage form in a stream, if any
+  (defun stream-defpackage-form (stream)
+    (loop :for form = (read stream nil nil) :while form
+          :when (defpackage-form-p form) :return form))
+
+  (defun file-defpackage-form (file)
+    "Return the first DEFPACKAGE form in FILE."
+    (with-input-file (f file)
+      (stream-defpackage-form f)))
+
+  (define-condition package-inferred-system-missing-package-error (system-definition-error)
+    ((system :initarg :system :reader error-system)
+     (pathname :initarg :pathname :reader error-pathname))
+    (:report (lambda (c s)
+               (format s (compatfmt "~@<No package form found while ~
+                                     trying to define package-inferred-system ~A from file ~A~>")
+                       (error-system c) (error-pathname c)))))
+
+  (defun package-dependencies (defpackage-form)
+    "Return a list of packages depended on by the package
+defined in DEFPACKAGE-FORM.  A package is depended upon if
+the DEFPACKAGE-FORM uses it or imports a symbol from it."
+    (assert (defpackage-form-p defpackage-form))
+    (remove-duplicates
+     (while-collecting (dep)
+       (loop :for (option . arguments) :in (cddr defpackage-form) :do
+         (ecase option
+           ((:use :mix :reexport :use-reexport :mix-reexport)
+            (dolist (p arguments) (dep (string p))))
+           ((:import-from :shadowing-import-from)
+            (dep (string (first arguments))))
+           #+package-local-nicknames
+           ((:local-nicknames)
+            (loop :for (nil actual-package-name) :in arguments :do
+              (dep (string actual-package-name))))
+           ((:nicknames :documentation :shadow :export :intern :unintern :recycle)))))
+     :from-end t :test 'equal))
+
+  (defun package-designator-name (package)
+    "Normalize a package designator to a string"
+    (etypecase package
+      (package (package-name package))
+      (string package)
+      (symbol (string package))))
+
+  (defun register-system-packages (system packages)
+    "Register SYSTEM as providing PACKAGES."
+    (let ((name (or (eq system t) (coerce-name system))))
+      (dolist (p (ensure-list packages))
+        (setf (gethash (package-designator-name p) *package-inferred-systems*) name))))
+
+  (defun package-name-system (package-name)
+    "Return the name of the SYSTEM providing PACKAGE-NAME, if such exists,
+otherwise return a default system name computed from PACKAGE-NAME."
+    (check-type package-name string)
+    (or (gethash package-name *package-inferred-systems*)
+        (string-downcase package-name)))
+
+  ;; Given a file in package-inferred-system style, find its dependencies
+  (defun package-inferred-system-file-dependencies (file &optional system)
+    (if-let (defpackage-form (file-defpackage-form file))
+      (remove t (mapcar 'package-name-system (package-dependencies defpackage-form)))
+      (error 'package-inferred-system-missing-package-error :system system :pathname file)))
+
+  ;; Given package-inferred-system object, check whether its specification matches
+  ;; the provided parameters
+  (defun same-package-inferred-system-p (system name directory subpath around-compile dependencies)
+    (and (eq (type-of system) 'package-inferred-system)
+         (equal (component-name system) name)
+         (pathname-equal directory (component-pathname system))
+         (equal dependencies (component-sideway-dependencies system))
+         (equal around-compile (around-compile-hook system))
+         (let ((children (component-children system)))
+           (and (length=n-p children 1)
+                (let ((child (first children)))
+                  (and (eq (type-of child) 'cl-source-file)
+                       (equal (component-name child) "lisp")
+                       (and (slot-boundp child 'relative-pathname)
+                            (equal (slot-value child 'relative-pathname) subpath))))))))
+
+  ;; sysdef search function to push into *system-definition-search-functions*
+  (defun sysdef-package-inferred-system-search (system-name)
+  "Takes SYSTEM-NAME and returns an initialized SYSTEM object, or NIL.  Made to be added to
+*SYSTEM-DEFINITION-SEARCH-FUNCTIONS*."
+    (let ((primary (primary-system-name system-name)))
+      ;; this function ONLY does something if the primary system name is NOT the same as
+      ;; SYSTEM-NAME.  It is used to find the systems with names that are relative to
+      ;; the primary system's name, and that are not explicitly specified in the system
+      ;; definition
+      (unless (equal primary system-name)
+        (let ((top (find-system primary nil)))
+          (when (typep top 'package-inferred-system)
+            (if-let (dir (component-pathname top))
+              (let* ((sub (subseq system-name (1+ (length primary))))
+                     (component-type (class-for-type top :file))
+                     (file-type (file-type (make-instance component-type)))
+                     (f (probe-file* (subpathname dir sub :type file-type)
+                                     :truename *resolve-symlinks*)))
+                (when (file-pathname-p f)
+                  (let ((dependencies (package-inferred-system-file-dependencies f system-name))
+                        (previous (registered-system system-name))
+                        (around-compile (around-compile-hook top)))
+                    (if (same-package-inferred-system-p previous system-name dir sub around-compile dependencies)
+                        previous
+                        (eval `(defsystem ,system-name
+                                 :class package-inferred-system
+                                 :default-component-class ,component-type
+                                 :source-file ,(system-source-file top)
+                                 :pathname ,dir
+                                 :depends-on ,dependencies
+                                 :around-compile ,around-compile
+                                 :components ((,component-type file-type :pathname ,sub)))))))))))))))
+
+(with-upgradability ()
+  (pushnew 'sysdef-package-inferred-system-search *system-definition-search-functions*)
+  (setf *system-definition-search-functions*
+        (remove (find-symbol* :sysdef-package-system-search :asdf/package-system nil)
+                *system-definition-search-functions*)))
+;;;; ---------------------------------------------------------------------------
+;;;; asdf-output-translations
+
+(uiop/package:define-package :asdf/output-translations
+  (:recycle :asdf/output-translations :asdf)
+  (:use :uiop/common-lisp :uiop :asdf/upgrade)
+  (:export
+   #:*output-translations* #:*output-translations-parameter*
+   #:invalid-output-translation
+   #:output-translations #:output-translations-initialized-p
+   #:initialize-output-translations #:clear-output-translations
+   #:disable-output-translations #:ensure-output-translations
+   #:apply-output-translations
+   #:validate-output-translations-directive #:validate-output-translations-form
+   #:validate-output-translations-file #:validate-output-translations-directory
+   #:parse-output-translations-string #:wrapping-output-translations
+   #:user-output-translations-pathname #:system-output-translations-pathname
+   #:user-output-translations-directory-pathname #:system-output-translations-directory-pathname
+   #:environment-output-translations #:process-output-translations
+   #:compute-output-translations
+   #+abcl #:translate-jar-pathname
+   ))
+(in-package :asdf/output-translations)
+
+;; (setf output-translations) between 2.27 and 3.0.3 was using a defsetf macro
+;; for the sake of obsolete versions of GCL 2.6. Make sure it doesn't come to haunt us.
+(when-upgrading (:version "3.1.2") (fmakunbound '(setf output-translations)))
+
+(with-upgradability ()
+  (define-condition invalid-output-translation (invalid-configuration warning)
+    ((format :initform (compatfmt "~@<Invalid asdf output-translation ~S~@[ in ~S~]~@{ ~@?~}~@:>"))))
+
+  (defvar *output-translations* ()
+    "Either NIL (for uninitialized), or a list of one element,
+said element itself being a sorted list of mappings.
+Each mapping is a pair of a source pathname and destination pathname,
+and the order is by decreasing length of namestring of the source pathname.")
+
+  (defun output-translations ()
+    "Return the configured output-translations, if any"
+    (car *output-translations*))
+
+  ;; Set the output-translations, by sorting the provided new-value.
+  (defun set-output-translations (new-value)
+    (setf *output-translations*
+          (list
+           (stable-sort (copy-list new-value) #'>
+                        :key #'(lambda (x)
+                                 (etypecase (car x)
+                                   ((eql t) -1)
+                                   (pathname
+                                    (let ((directory
+                                           (normalize-pathname-directory-component
+                                            (pathname-directory (car x)))))
+                                      (if (listp directory) (length directory) 0))))))))
+    new-value)
+  (defun (setf output-translations) (new-value) (set-output-translations new-value))
+
+  (defun output-translations-initialized-p ()
+    "Have the output-translations been initialized yet?"
+    (and *output-translations* t))
+
+  (defun clear-output-translations ()
+    "Undoes any initialization of the output translations."
+    (setf *output-translations* '())
+    (values))
+  (register-clear-configuration-hook 'clear-output-translations)
+
+
+  ;;; Validation of the configuration directives...
+
+  (defun validate-output-translations-directive (directive)
+    (or (member directive '(:enable-user-cache :disable-cache nil))
+        (and (consp directive)
+             (or (and (length=n-p directive 2)
+                      (or (and (eq (first directive) :include)
+                               (typep (second directive) '(or string pathname null)))
+                          (and (location-designator-p (first directive))
+                               (or (location-designator-p (second directive))
+                                   (location-function-p (second directive))))))
+                 (and (length=n-p directive 1)
+                      (location-designator-p (first directive)))))))
+
+  (defun validate-output-translations-form (form &key location)
+    (validate-configuration-form
+     form
+     :output-translations
+     'validate-output-translations-directive
+     :location location :invalid-form-reporter 'invalid-output-translation))
+
+  (defun validate-output-translations-file (file)
+    (validate-configuration-file
+     file 'validate-output-translations-form :description "output translations"))
+
+  (defun validate-output-translations-directory (directory)
+    (validate-configuration-directory
+     directory :output-translations 'validate-output-translations-directive
+               :invalid-form-reporter 'invalid-output-translation))
+
+
+  ;;; Parse the ASDF_OUTPUT_TRANSLATIONS environment variable and/or some file contents
+  (defun parse-output-translations-string (string &key location)
+    (cond
+      ((or (null string) (equal string ""))
+       '(:output-translations :inherit-configuration))
+      ((not (stringp string))
+       (error (compatfmt "~@<Environment string isn't: ~3i~_~S~@:>") string))
+      ((eql (char string 0) #\")
+       (parse-output-translations-string (read-from-string string) :location location))
+      ((eql (char string 0) #\()
+       (validate-output-translations-form (read-from-string string) :location location))
+      (t
+       (loop
+         :with inherit = nil
+         :with directives = ()
+         :with start = 0
+         :with end = (length string)
+         :with source = nil
+         :with separator = (inter-directory-separator)
+         :for i = (or (position separator string :start start) end) :do
+           (let ((s (subseq string start i)))
+             (cond
+               (source
+                (push (list source (if (equal "" s) nil s)) directives)
+                (setf source nil))
+               ((equal "" s)
+                (when inherit
+                  (error (compatfmt "~@<Only one inherited configuration allowed: ~3i~_~S~@:>")
+                         string))
+                (setf inherit t)
+                (push :inherit-configuration directives))
+               (t
+                (setf source s)))
+             (setf start (1+ i))
+             (when (> start end)
+               (when source
+                 (error (compatfmt "~@<Uneven number of components in source to destination mapping: ~3i~_~S~@:>")
+                        string))
+               (unless inherit
+                 (push :ignore-inherited-configuration directives))
+               (return `(:output-translations ,@(nreverse directives)))))))))
+
+
+  ;; The default sources of configuration for output-translations
+  (defparameter* *default-output-translations*
+    '(environment-output-translations
+      user-output-translations-pathname
+      user-output-translations-directory-pathname
+      system-output-translations-pathname
+      system-output-translations-directory-pathname))
+
+  ;; Compulsory implementation-dependent wrapping for the translations:
+  ;; handle implementation-provided systems.
+  (defun wrapping-output-translations ()
+    `(:output-translations
+    ;; Some implementations have precompiled ASDF systems,
+    ;; so we must disable translations for implementation paths.
+      #+(or clasp #|clozure|# ecl mkcl sbcl)
+      ,@(let ((h (resolve-symlinks* (lisp-implementation-directory))))
+          (when h `(((,h ,*wild-path*) ()))))
+      #+mkcl (,(translate-logical-pathname "CONTRIB:") ())
+      ;; All-import, here is where we want user stuff to be:
+      :inherit-configuration
+      ;; These are for convenience, and can be overridden by the user:
+      #+abcl (#p"/___jar___file___root___/**/*.*" (:user-cache #p"**/*.*"))
+      #+abcl (#p"jar:file:/**/*.jar!/**/*.*" (:function translate-jar-pathname))
+      ;; We enable the user cache by default, and here is the place we do:
+      :enable-user-cache))
+
+  ;; Relative pathnames of output-translations configuration to XDG configuration directory
+  (defparameter *output-translations-file* (parse-unix-namestring "common-lisp/asdf-output-translations.conf"))
+  (defparameter *output-translations-directory* (parse-unix-namestring "common-lisp/asdf-output-translations.conf.d/"))
+
+  ;; Locating various configuration pathnames, depending on input or output intent.
+  (defun user-output-translations-pathname (&key (direction :input))
+    (xdg-config-pathname *output-translations-file* direction))
+  (defun system-output-translations-pathname (&key (direction :input))
+    (find-preferred-file (system-config-pathnames *output-translations-file*)
+                         :direction direction))
+  (defun user-output-translations-directory-pathname (&key (direction :input))
+    (xdg-config-pathname *output-translations-directory* direction))
+  (defun system-output-translations-directory-pathname (&key (direction :input))
+    (find-preferred-file (system-config-pathnames *output-translations-directory*)
+                         :direction direction))
+  (defun environment-output-translations ()
+    (getenv "ASDF_OUTPUT_TRANSLATIONS"))
+
+
+  ;;; Processing the configuration.
+
+  (defgeneric process-output-translations (spec &key inherit collect))
+
+  (defun inherit-output-translations (inherit &key collect)
+    (when inherit
+      (process-output-translations (first inherit) :collect collect :inherit (rest inherit))))
+
+  (defun process-output-translations-directive (directive &key inherit collect)
+    (if (atom directive)
+        (ecase directive
+          ((:enable-user-cache)
+           (process-output-translations-directive '(t :user-cache) :collect collect))
+          ((:disable-cache)
+           (process-output-translations-directive '(t t) :collect collect))
+          ((:inherit-configuration)
+           (inherit-output-translations inherit :collect collect))
+          ((:ignore-inherited-configuration :ignore-invalid-entries nil)
+           nil))
+        (let ((src (first directive))
+              (dst (second directive)))
+          (if (eq src :include)
+              (when dst
+                (process-output-translations (pathname dst) :inherit nil :collect collect))
+              (when src
+                (let ((trusrc (or (eql src t)
+                                  (let ((loc (resolve-location src :ensure-directory t :wilden t)))
+                                    (if (absolute-pathname-p loc) (resolve-symlinks* loc) loc)))))
+                  (cond
+                    ((location-function-p dst)
+                     (funcall collect
+                              (list trusrc (ensure-function (second dst)))))
+                    ((typep dst 'boolean)
+                     (funcall collect (list trusrc t)))
+                    (t
+                     (let* ((trudst (resolve-location dst :ensure-directory t :wilden t)))
+                       (funcall collect (list trudst t))
+                       (funcall collect (list trusrc trudst)))))))))))
+
+  (defmethod process-output-translations ((x symbol) &key
+                                                       (inherit *default-output-translations*)
+                                                       collect)
+    (process-output-translations (funcall x) :inherit inherit :collect collect))
+  (defmethod process-output-translations ((pathname pathname) &key inherit collect)
+    (cond
+      ((directory-pathname-p pathname)
+       (process-output-translations (validate-output-translations-directory pathname)
+                                    :inherit inherit :collect collect))
+      ((probe-file* pathname :truename *resolve-symlinks*)
+       (process-output-translations (validate-output-translations-file pathname)
+                                    :inherit inherit :collect collect))
+      (t
+       (inherit-output-translations inherit :collect collect))))
+  (defmethod process-output-translations ((string string) &key inherit collect)
+    (process-output-translations (parse-output-translations-string string)
+                                 :inherit inherit :collect collect))
+  (defmethod process-output-translations ((x null) &key inherit collect)
+    (inherit-output-translations inherit :collect collect))
+  (defmethod process-output-translations ((form cons) &key inherit collect)
+    (dolist (directive (cdr (validate-output-translations-form form)))
+      (process-output-translations-directive directive :inherit inherit :collect collect)))
+
+
+  ;;; Top-level entry-points to configure output-translations
+
+  (defun compute-output-translations (&optional parameter)
+    "read the configuration, return it"
+    (remove-duplicates
+     (while-collecting (c)
+       (inherit-output-translations
+        `(wrapping-output-translations ,parameter ,@*default-output-translations*) :collect #'c))
+     :test 'equal :from-end t))
+
+  ;; Saving the user-provided parameter to output-translations, if any,
+  ;; so we can recompute the translations after code upgrade.
+  (defvar *output-translations-parameter* nil)
+
+  ;; Main entry-point for users.
+  (defun initialize-output-translations (&optional (parameter *output-translations-parameter*))
+    "read the configuration, initialize the internal configuration variable,
+return the configuration"
+    (setf *output-translations-parameter* parameter
+          (output-translations) (compute-output-translations parameter)))
+
+  (defun disable-output-translations ()
+    "Initialize output translations in a way that maps every file to itself,
+effectively disabling the output translation facility."
+    (initialize-output-translations
+     '(:output-translations :disable-cache :ignore-inherited-configuration)))
+
+  ;; checks an initial variable to see whether the state is initialized
+  ;; or cleared. In the former case, return current configuration; in
+  ;; the latter, initialize.  ASDF will call this function at the start
+  ;; of (asdf:find-system).
+  (defun ensure-output-translations ()
+    (if (output-translations-initialized-p)
+        (output-translations)
+        (initialize-output-translations)))
+
+
+  ;; Top-level entry-point to _use_ output-translations
+  (defun apply-output-translations (path)
+    (etypecase path
+      (logical-pathname
+       path)
+      ((or pathname string)
+       (ensure-output-translations)
+       (loop :with p = (resolve-symlinks* path)
+             :for (source destination) :in (car *output-translations*)
+             :for root = (when (or (eq source t)
+                                   (and (pathnamep source)
+                                        (not (absolute-pathname-p source))))
+                           (pathname-root p))
+             :for absolute-source = (cond
+                                      ((eq source t) (wilden root))
+                                      (root (merge-pathnames* source root))
+                                      (t source))
+             :when (or (eq source t) (pathname-match-p p absolute-source))
+               :return (translate-pathname* p absolute-source destination root source)
+             :finally (return p)))))
+
+
+  ;; Hook into uiop's output-translation mechanism
+  #-cormanlisp
+  (setf *output-translation-function* 'apply-output-translations)
+
+
+  ;;; Implementation-dependent hacks
+  #+abcl ;; ABCL: make it possible to use systems provided in the ABCL jar.
+  (defun translate-jar-pathname (source wildcard)
+    (declare (ignore wildcard))
+    (flet ((normalize-device (pathname)
+             (if (find :windows *features*)
+                 pathname
+                 (make-pathname :defaults pathname :device :unspecific))))
+      (let* ((jar
+               (pathname (first (pathname-device source))))
+             (target-root-directory-namestring
+               (format nil "/___jar___file___root___/~@[~A/~]"
+                       (and (find :windows *features*)
+                            (pathname-device jar))))
+             (relative-source
+               (relativize-pathname-directory source))
+             (relative-jar
+               (relativize-pathname-directory (ensure-directory-pathname jar)))
+             (target-root-directory
+               (normalize-device
+                (pathname-directory-pathname
+                 (parse-namestring target-root-directory-namestring))))
+             (target-root
+               (merge-pathnames* relative-jar target-root-directory))
+             (target
+               (merge-pathnames* relative-source target-root)))
+        (normalize-device (apply-output-translations target))))))
+
+;;;; -----------------------------------------------------------------
+;;;; Source Registry Configuration, by Francois-Rene Rideau
+;;;; See the Manual and https://bugs.launchpad.net/asdf/+bug/485918
+
+(uiop/package:define-package :asdf/source-registry
+  ;; NB: asdf/find-system allows upgrade from <=3.2.1 that have initialize-source-registry there
+  (:recycle :asdf/source-registry :asdf/find-system :asdf)
+  (:use :uiop/common-lisp :uiop :asdf/upgrade :asdf/system :asdf/system-registry)
+  (:export
+   #:*source-registry-parameter* #:*default-source-registries*
+   #:invalid-source-registry
+   #:source-registry-initialized-p
+   #:initialize-source-registry #:clear-source-registry #:*source-registry*
+   #:ensure-source-registry #:*source-registry-parameter*
+   #:*default-source-registry-exclusions* #:*source-registry-exclusions*
+   #:*wild-asd* #:directory-asd-files #:register-asd-directory
+   #:*recurse-beyond-asds* #:collect-asds-in-directory #:collect-sub*directories-asd-files
+   #:validate-source-registry-directive #:validate-source-registry-form
+   #:validate-source-registry-file #:validate-source-registry-directory
+   #:parse-source-registry-string #:wrapping-source-registry
+   #:default-user-source-registry #:default-system-source-registry
+   #:user-source-registry #:system-source-registry
+   #:user-source-registry-directory #:system-source-registry-directory
+   #:environment-source-registry #:process-source-registry #:inherit-source-registry
+   #:compute-source-registry #:flatten-source-registry
+   #:sysdef-source-registry-search))
+(in-package :asdf/source-registry)
+
+(with-upgradability ()
+  (define-condition invalid-source-registry (invalid-configuration warning)
+    ((format :initform (compatfmt "~@<Invalid source registry ~S~@[ in ~S~]~@{ ~@?~}~@:>"))))
+
+  ;; Default list of directories under which the source-registry tree search won't recurse
+  (defvar *default-source-registry-exclusions*
+    '(;;-- Using ack 1.2 exclusions
+      ".bzr" ".cdv"
+      ;; "~.dep" "~.dot" "~.nib" "~.plst" ; we don't support ack wildcards
+      ".git" ".hg" ".pc" ".svn" "CVS" "RCS" "SCCS" "_darcs"
+      "_sgbak" "autom4te.cache" "cover_db" "_build"
+      ;;-- debian often builds stuff under the debian directory... BAD.
+      "debian"))
+
+  ;; Actual list of directories under which the source-registry tree search won't recurse
+  (defvar *source-registry-exclusions* *default-source-registry-exclusions*)
+
+  ;; The state of the source-registry after search in configured locations
+  (defvar *source-registry* nil
+    "Either NIL (for uninitialized), or an equal hash-table, mapping
+system names to pathnames of .asd files")
+
+  ;; Saving the user-provided parameter to the source-registry, if any,
+  ;; so we can recompute the source-registry after code upgrade.
+  (defvar *source-registry-parameter* nil)
+
+  (defun source-registry-initialized-p ()
+    (typep *source-registry* 'hash-table))
+
+  (defun clear-source-registry ()
+    "Undoes any initialization of the source registry."
+    (setf *source-registry* nil)
+    (values))
+  (register-clear-configuration-hook 'clear-source-registry)
+
+  (defparameter *wild-asd*
+    (make-pathname :directory nil :name *wild* :type "asd" :version :newest))
+
+  (defun directory-asd-files (directory)
+    (directory-files directory *wild-asd*))
+
+  (defun collect-asds-in-directory (directory collect)
+    (let ((asds (directory-asd-files directory)))
+      (map () collect asds)
+      asds))
+
+  (defvar *recurse-beyond-asds* t
+    "Should :tree entries of the source-registry recurse in subdirectories
+after having found a .asd file? True by default.")
+
+  ;; When walking down a filesystem tree, if in a directory there is a .cl-source-registry.cache,
+  ;; read its contents instead of further recursively querying the filesystem.
+  (defun process-source-registry-cache (directory collect)
+    (let ((cache (ignore-errors
+                  (safe-read-file-form (subpathname directory ".cl-source-registry.cache")))))
+      (when (and (listp cache) (eq :source-registry-cache (first cache)))
+        (loop :for s :in (rest cache) :do (funcall collect (subpathname directory s)))
+        t)))
+
+  (defun collect-sub*directories-asd-files
+      (directory &key (exclude *default-source-registry-exclusions*) collect
+                   (recurse-beyond-asds *recurse-beyond-asds*) ignore-cache)
+    (let ((visited (make-hash-table :test 'equalp)))
+      (flet ((collectp (dir)
+               (unless (and (not ignore-cache) (process-source-registry-cache dir collect))
+                 (let ((asds (collect-asds-in-directory dir collect)))
+                   (or recurse-beyond-asds (not asds)))))
+             (recursep (x)                    ; x will be a directory pathname
+               (and
+                (not (member (car (last (pathname-directory x))) exclude :test #'equal))
+                (flet ((pathname-key (x)
+                         (namestring (truename* x))))
+                  (let ((visitedp (gethash (pathname-key x) visited)))
+                    (if visitedp nil
+                        (setf (gethash (pathname-key x) visited) t)))))))
+      (collect-sub*directories directory #'collectp #'recursep (constantly nil)))))
+
+
+  ;;; Validate the configuration forms
+
+  (defun validate-source-registry-directive (directive)
+    (or (member directive '(:default-registry))
+        (and (consp directive)
+             (let ((rest (rest directive)))
+               (case (first directive)
+                 ((:include :directory :tree)
+                  (and (length=n-p rest 1)
+                       (location-designator-p (first rest))))
+                 ((:exclude :also-exclude)
+                  (every #'stringp rest))
+                 ((:default-registry)
+                  (null rest)))))))
+
+  (defun validate-source-registry-form (form &key location)
+    (validate-configuration-form
+     form :source-registry 'validate-source-registry-directive
+          :location location :invalid-form-reporter 'invalid-source-registry))
+
+  (defun validate-source-registry-file (file)
+    (validate-configuration-file
+     file 'validate-source-registry-form :description "a source registry"))
+
+  (defun validate-source-registry-directory (directory)
+    (validate-configuration-directory
+     directory :source-registry 'validate-source-registry-directive
+               :invalid-form-reporter 'invalid-source-registry))
+
+
+  ;;; Parse the configuration string
+
+  (defun parse-source-registry-string (string &key location)
+    (cond
+      ((or (null string) (equal string ""))
+       '(:source-registry :inherit-configuration))
+      ((not (stringp string))
+       (error (compatfmt "~@<Environment string isn't: ~3i~_~S~@:>") string))
+      ((find (char string 0) "\"(")
+       (validate-source-registry-form (read-from-string string) :location location))
+      (t
+       (loop
+         :with inherit = nil
+         :with directives = ()
+         :with start = 0
+         :with end = (length string)
+         :with separator = (inter-directory-separator)
+         :for pos = (position separator string :start start) :do
+           (let ((s (subseq string start (or pos end))))
+             (flet ((check (dir)
+                      (unless (absolute-pathname-p dir)
+                        (error (compatfmt "~@<source-registry string must specify absolute pathnames: ~3i~_~S~@:>") string))
+                      dir))
+               (cond
+                 ((equal "" s) ; empty element: inherit
+                  (when inherit
+                    (error (compatfmt "~@<Only one inherited configuration allowed: ~3i~_~S~@:>")
+                           string))
+                  (setf inherit t)
+                  (push ':inherit-configuration directives))
+                 ((string-suffix-p s "//") ;; TODO: allow for doubling of separator even outside Unix?
+                  (push `(:tree ,(check (subseq s 0 (- (length s) 2)))) directives))
+                 (t
+                  (push `(:directory ,(check s)) directives))))
+             (cond
+               (pos
+                (setf start (1+ pos)))
+               (t
+                (unless inherit
+                  (push '(:ignore-inherited-configuration) directives))
+                (return `(:source-registry ,@(nreverse directives))))))))))
+
+  (defun register-asd-directory (directory &key recurse exclude collect)
+    (if (not recurse)
+        (collect-asds-in-directory directory collect)
+        (collect-sub*directories-asd-files
+         directory :exclude exclude :collect collect)))
+
+  (defparameter* *default-source-registries*
+    '(environment-source-registry
+      user-source-registry
+      user-source-registry-directory
+      default-user-source-registry
+      system-source-registry
+      system-source-registry-directory
+      default-system-source-registry)
+    "List of default source registries" "3.1.0.102")
+
+  (defparameter *source-registry-file* (parse-unix-namestring "common-lisp/source-registry.conf"))
+  (defparameter *source-registry-directory* (parse-unix-namestring "common-lisp/source-registry.conf.d/"))
+
+  (defun wrapping-source-registry ()
+    `(:source-registry
+      #+(or clasp ecl sbcl) (:tree ,(resolve-symlinks* (lisp-implementation-directory)))
+      :inherit-configuration
+      #+mkcl (:tree ,(translate-logical-pathname "SYS:"))
+      #+cmucl (:tree #p"modules:")
+      #+scl (:tree #p"file://modules/")))
+  (defun default-user-source-registry ()
+    `(:source-registry
+      (:tree (:home "common-lisp/"))
+      #+sbcl (:directory (:home ".sbcl/systems/"))
+      (:directory ,(xdg-data-home "common-lisp/systems/"))
+      (:tree ,(xdg-data-home "common-lisp/source/"))
+      :inherit-configuration))
+  (defun default-system-source-registry ()
+    `(:source-registry
+      ,@(loop :for dir :in (xdg-data-dirs "common-lisp/")
+              :collect `(:directory (,dir "systems/"))
+              :collect `(:tree (,dir "source/")))
+      :inherit-configuration))
+  (defun user-source-registry (&key (direction :input))
+    (xdg-config-pathname *source-registry-file* direction))
+  (defun system-source-registry (&key (direction :input))
+    (find-preferred-file (system-config-pathnames *source-registry-file*)
+                         :direction direction))
+  (defun user-source-registry-directory (&key (direction :input))
+    (xdg-config-pathname *source-registry-directory* direction))
+  (defun system-source-registry-directory (&key (direction :input))
+    (find-preferred-file (system-config-pathnames *source-registry-directory*)
+                         :direction direction))
+  (defun environment-source-registry ()
+    (getenv "CL_SOURCE_REGISTRY"))
+
+
+  ;;; Process the source-registry configuration
+
+  (defgeneric process-source-registry (spec &key inherit register))
+
+  (defun inherit-source-registry (inherit &key register)
+    (when inherit
+      (process-source-registry (first inherit) :register register :inherit (rest inherit))))
+
+  (defun process-source-registry-directive (directive &key inherit register)
+    (destructuring-bind (kw &rest rest) (if (consp directive) directive (list directive))
+      (ecase kw
+        ((:include)
+         (destructuring-bind (pathname) rest
+           (process-source-registry (resolve-location pathname) :inherit nil :register register)))
+        ((:directory)
+         (destructuring-bind (pathname) rest
+           (when pathname
+             (funcall register (resolve-location pathname :ensure-directory t)))))
+        ((:tree)
+         (destructuring-bind (pathname) rest
+           (when pathname
+             (funcall register (resolve-location pathname :ensure-directory t)
+                      :recurse t :exclude *source-registry-exclusions*))))
+        ((:exclude)
+         (setf *source-registry-exclusions* rest))
+        ((:also-exclude)
+         (appendf *source-registry-exclusions* rest))
+        ((:default-registry)
+         (inherit-source-registry
+          '(default-user-source-registry default-system-source-registry) :register register))
+        ((:inherit-configuration)
+         (inherit-source-registry inherit :register register))
+        ((:ignore-inherited-configuration)
+         nil)))
+    nil)
+
+  (defmethod process-source-registry ((x symbol) &key inherit register)
+    (process-source-registry (funcall x) :inherit inherit :register register))
+  (defmethod process-source-registry ((pathname pathname) &key inherit register)
+    (cond
+      ((directory-pathname-p pathname)
+       (let ((*here-directory* (resolve-symlinks* pathname)))
+         (process-source-registry (validate-source-registry-directory pathname)
+                                  :inherit inherit :register register)))
+      ((probe-file* pathname :truename *resolve-symlinks*)
+       (let ((*here-directory* (pathname-directory-pathname pathname)))
+         (process-source-registry (validate-source-registry-file pathname)
+                                  :inherit inherit :register register)))
+      (t
+       (inherit-source-registry inherit :register register))))
+  (defmethod process-source-registry ((string string) &key inherit register)
+    (process-source-registry (parse-source-registry-string string)
+                             :inherit inherit :register register))
+  (defmethod process-source-registry ((x null) &key inherit register)
+    (inherit-source-registry inherit :register register))
+  (defmethod process-source-registry ((form cons) &key inherit register)
+    (let ((*source-registry-exclusions* *default-source-registry-exclusions*))
+      (dolist (directive (cdr (validate-source-registry-form form)))
+        (process-source-registry-directive directive :inherit inherit :register register))))
+
+
+  ;; Flatten the user-provided configuration into an ordered list of directories and trees
+  (defun flatten-source-registry (&optional (parameter *source-registry-parameter*))
+    (remove-duplicates
+     (while-collecting (collect)
+       (with-pathname-defaults () ;; be location-independent
+         (inherit-source-registry
+          `(wrapping-source-registry
+            ,parameter
+            ,@*default-source-registries*)
+          :register #'(lambda (directory &key recurse exclude)
+                        (collect (list directory :recurse recurse :exclude exclude))))))
+     :test 'equal :from-end t))
+
+  ;; MAYBE: move this utility function to uiop/pathname and export it?
+  (defun pathname-directory-depth (p)
+    (length (normalize-pathname-directory-component (pathname-directory p))))
+
+  (defun preferred-source-path-p (x y)
+    "Return T iff X is to be preferred over Y as a source path"
+    (let ((lx (pathname-directory-depth x))
+          (ly (pathname-directory-depth y)))
+      (or (< lx ly)
+          (and (= lx ly)
+               (string< (namestring x)
+                        (namestring y))))))
+
+  ;; Will read the configuration and initialize all internal variables.
+  (defun compute-source-registry (&optional (parameter *source-registry-parameter*)
+                                    (registry *source-registry*))
+    (dolist (entry (flatten-source-registry parameter))
+      (destructuring-bind (directory &key recurse exclude) entry
+        (let* ((h (make-hash-table :test 'equal))) ; table to detect duplicates
+          (register-asd-directory
+           directory :recurse recurse :exclude exclude :collect
+           #'(lambda (asd)
+               (let* ((name (pathname-name asd))
+                      (name (if (typep asd 'logical-pathname)
+                                ;; logical pathnames are upper-case,
+                                ;; at least in the CLHS and on SBCL,
+                                ;; yet (coerce-name :foo) is lower-case.
+                                ;; won't work well with (load-system "Foo")
+                                ;; instead of (load-system 'foo)
+                                (string-downcase name)
+                                name)))
+                 (unless (gethash name registry) ; already shadowed by something else
+                   (if-let (old (gethash name h))
+                     ;; If the name appears multiple times,
+                     ;; prefer the one with the shallowest directory,
+                     ;; or if they have same depth, compare unix-namestring with string<
+                     (multiple-value-bind (better worse)
+                         (if (preferred-source-path-p asd old)
+                             (progn (setf (gethash name h) asd) (values asd old))
+                             (values old asd))
+                       (when *verbose-out*
+                         (warn (compatfmt "~@<In source-registry entry ~A~@[/~*~] ~
+                                              found several entries for ~A - picking ~S over ~S~:>")
+                               directory recurse name better worse)))
+                     (setf (gethash name h) asd))))))
+          (maphash #'(lambda (k v) (setf (gethash k registry) v)) h))))
+    (values))
+
+  (defun initialize-source-registry (&optional (parameter *source-registry-parameter*))
+    ;; Record the parameter used to configure the registry
+    (setf *source-registry-parameter* parameter)
+    ;; Clear the previous registry database:
+    (setf *source-registry* (make-hash-table :test 'equal))
+    ;; Do it!
+    (compute-source-registry parameter))
+
+  ;; Checks an initial variable to see whether the state is initialized
+  ;; or cleared. In the former case, return current configuration; in
+  ;; the latter, initialize.  ASDF will call this function at the start
+  ;; of (asdf:find-system) to make sure the source registry is initialized.
+  ;; However, it will do so *without* a parameter, at which point it
+  ;; will be too late to provide a parameter to this function, though
+  ;; you may override the configuration explicitly by calling
+  ;; initialize-source-registry directly with your parameter.
+  (defun ensure-source-registry (&optional parameter)
+    (unless (source-registry-initialized-p)
+      (initialize-source-registry parameter))
+    (values))
+
+  (defun sysdef-source-registry-search (system)
+    (ensure-source-registry)
+    (values (gethash (primary-system-name system) *source-registry*))))
+
+
+;;;; -------------------------------------------------------------------------
+;;; Internal hacks for backward-compatibility
+
+(uiop/package:define-package :asdf/backward-internals
+  (:recycle :asdf/backward-internals :asdf)
+  (:use :uiop/common-lisp :uiop :asdf/upgrade :asdf/find-system)
+  (:export #:load-sysdef))
+(in-package :asdf/backward-internals)
+
+(with-asdf-deprecation (:style-warning "3.2" :warning "3.4")
+  (defun load-sysdef (name pathname)
+    (declare (ignore name pathname))
+    ;; Needed for backward compatibility with swank-asdf from SLIME 2015-12-01 or older.
+    (error "Use asdf:load-asd instead of asdf::load-sysdef")))
+;;;; -------------------------------------------------------------------------
+;;; Backward-compatible interfaces
+
+(uiop/package:define-package :asdf/backward-interface
+  (:recycle :asdf/backward-interface :asdf)
+  (:use :uiop/common-lisp :uiop :asdf/upgrade :asdf/session
+   :asdf/component :asdf/system :asdf/system-registry :asdf/operation :asdf/action
+   :asdf/lisp-action :asdf/plan :asdf/operate
+   :asdf/find-system :asdf/parse-defsystem :asdf/output-translations :asdf/bundle)
+  (:export
+   #:*asdf-verbose*
+   #:operation-error #:compile-error #:compile-failed #:compile-warned
+   #:error-component #:error-operation #:traverse
+   #:component-load-dependencies
+   #:enable-asdf-binary-locations-compatibility
+   #:operation-on-failure #:operation-on-warnings #:on-failure #:on-warnings
+   #:component-property
+   #:run-shell-command
+   #:system-definition-pathname #:system-registered-p #:require-system
+   #:explain
+   #+ecl #:make-build))
+(in-package :asdf/backward-interface)
+
+;; NB: the warning status of these functions may have to be distinguished later,
+;; as some get removed faster than the others in client code.
+(with-asdf-deprecation (:style-warning "3.2" :warning "3.4")
+
+  ;; These conditions from ASDF 1 and 2 are used by many packages in Quicklisp;
+  ;; but ASDF3 replaced them with somewhat different variants of uiop:compile-condition
+  ;; that do not involve ASDF actions.
+  ;; TODO: find the offenders and stop them.
+  (progn
+    (define-condition operation-error (error) ;; Bad, backward-compatible name
+      ;; Used by SBCL, cffi-tests, clsql-mysql, clsql-uffi, qt, elephant, uffi-tests, sb-grovel
+      ((component :reader error-component :initarg :component)
+       (operation :reader error-operation :initarg :operation))
+      (:report (lambda (c s)
+                 (format s (compatfmt "~@<~A while invoking ~A on ~A~@:>")
+                         (type-of c) (error-operation c) (error-component c)))))
+    (define-condition compile-error (operation-error) ())
+    (define-condition compile-failed (compile-error) ())
+    (define-condition compile-warned (compile-error) ()))
+
+  ;; In Quicklisp 2015-05, still used by lisp-executable, staple, repl-utilities, cffi
+  (defun component-load-dependencies (component) ;; from ASDF 2.000 to 2.26
+    "DEPRECATED. Please use COMPONENT-SIDEWAY-DEPENDENCIES instead; or better,
+define your operations with proper use of SIDEWAY-OPERATION, SELFWARD-OPERATION,
+or define methods on PREPARE-OP, etc."
+    ;; Old deprecated name for the same thing. Please update your software.
+    (component-sideway-dependencies component))
+
+  ;; These old interfaces from ASDF1 have never been very meaningful
+  ;; but are still used in obscure places.
+  ;; In Quicklisp 2015-05, still used by cl-protobufs and clx.
+  (defgeneric operation-on-warnings (operation)
+    (:documentation "DEPRECATED. Please use UIOP:*COMPILE-FILE-WARNINGS-BEHAVIOUR* instead."))
+  (defgeneric operation-on-failure (operation)
+    (:documentation "DEPRECATED. Please use UIOP:*COMPILE-FILE-FAILURE-BEHAVIOUR* instead."))
+  (defgeneric (setf operation-on-warnings) (x operation)
+    (:documentation "DEPRECATED. Please SETF UIOP:*COMPILE-FILE-WARNINGS-BEHAVIOUR* instead."))
+  (defgeneric (setf operation-on-failure) (x operation)
+    (:documentation "DEPRECATED. Please SETF UIOP:*COMPILE-FILE-FAILURE-BEHAVIOUR* instead."))
+  (progn
+    (defmethod operation-on-warnings ((o operation))
+      *compile-file-warnings-behaviour*)
+    (defmethod operation-on-failure ((o operation))
+      *compile-file-failure-behaviour*)
+    (defmethod (setf operation-on-warnings) (x (o operation))
+      (setf *compile-file-warnings-behaviour* x))
+    (defmethod (setf operation-on-failure) (x (o operation))
+      (setf *compile-file-failure-behaviour* x)))
+
+  ;; Quicklisp 2015-05: Still used by SLIME's swank-asdf (!), common-lisp-stat,
+  ;; js-parser, osicat, babel, staple, weblocks, cl-png, plain-odbc, autoproject,
+  ;; cl-blapack, com.informatimago, cells-gtk3, asdf-dependency-grovel,
+  ;; cl-glfw, cffi, jwacs, montezuma
+  (defun system-definition-pathname (x)
+    ;; As of 2.014.8, we mean to make this function obsolete,
+    ;; but that won't happen until all clients have been updated.
+    "DEPRECATED. This function used to expose ASDF internals with subtle
+differences with respect to user expectations, that have been refactored
+away since. We recommend you use ASDF:SYSTEM-SOURCE-FILE instead for a
+mostly compatible replacement that we're supporting, or even
+ASDF:SYSTEM-SOURCE-DIRECTORY or ASDF:SYSTEM-RELATIVE-PATHNAME
+if that's whay you mean." ;;)
+    (system-source-file x))
+
+  ;; TRAVERSE is the function used to compute a plan in ASDF 1 and 2.
+  ;; It was never officially exposed but some people still used it.
+  (defgeneric traverse (operation component &key &allow-other-keys)
+    (:documentation
+     "DEPRECATED. Use MAKE-PLAN and PLAN-ACTIONS, or REQUIRED-COMPONENTS,
+or some other supported interface instead.
+
+Generate and return a plan for performing OPERATION on COMPONENT.
+
+The plan returned is a list of dotted-pairs. Each pair is the CONS
+of ASDF operation object and a COMPONENT object. The pairs will be
+processed in order by OPERATE."))
+  (progn
+    (define-convenience-action-methods traverse (operation component &key)))
+  (defmethod traverse ((o operation) (c component) &rest keys &key plan-class &allow-other-keys)
+    (plan-actions (apply 'make-plan plan-class o c keys)))
+
+
+  ;; ASDF-Binary-Locations compatibility
+  ;; This remains supported for legacy user, but not recommended for new users.
+  ;; We suspect there are no more legacy users in 2016.
+  (defun enable-asdf-binary-locations-compatibility
+      (&key
+         (centralize-lisp-binaries nil)
+         (default-toplevel-directory
+             ;; Use ".cache/common-lisp/" instead ???
+             (subpathname (user-homedir-pathname) ".fasls/"))
+         (include-per-user-information nil)
+         (map-all-source-files (or #+(or clasp clisp ecl mkcl) t nil))
+         (source-to-target-mappings nil)
+         (file-types `(,(compile-file-type)
+                        "build-report"
+                        #+clasp (compile-file-type :output-type :object)
+                        #+ecl (compile-file-type :type :object)
+                        #+mkcl (compile-file-type :fasl-p nil)
+                        #+clisp "lib" #+sbcl "cfasl"
+                        #+sbcl "sbcl-warnings" #+clozure "ccl-warnings")))
+    "DEPRECATED. Use asdf-output-translations instead."
+    #+(or clasp clisp ecl mkcl)
+    (when (null map-all-source-files)
+      (error "asdf:enable-asdf-binary-locations-compatibility doesn't support :map-all-source-files nil on CLISP, ECL and MKCL"))
+    (let* ((patterns (if map-all-source-files (list *wild-file*)
+                         (loop :for type :in file-types
+                           :collect (make-pathname :type type :defaults *wild-file*))))
+           (destination-directory
+            (if centralize-lisp-binaries
+                `(,default-toplevel-directory
+                     ,@(when include-per-user-information
+                             (cdr (pathname-directory (user-homedir-pathname))))
+                     :implementation ,*wild-inferiors*)
+                `(:root ,*wild-inferiors* :implementation))))
+      (initialize-output-translations
+       `(:output-translations
+         ,@source-to-target-mappings
+         #+abcl (#p"jar:file:/**/*.jar!/**/*.*" (:function translate-jar-pathname))
+         #+abcl (#p"/___jar___file___root___/**/*.*" (,@destination-directory))
+         ,@(loop :for pattern :in patterns
+             :collect `((:root ,*wild-inferiors* ,pattern)
+                        (,@destination-directory ,pattern)))
+         (t t)
+         :ignore-inherited-configuration))))
+  (progn
+    (defmethod operate :before (operation-class system &rest args &key &allow-other-keys)
+      (declare (ignore operation-class system args))
+      (when (find-symbol* '#:output-files-for-system-and-operation :asdf nil)
+        (error "ASDF 2 is not compatible with ASDF-BINARY-LOCATIONS, which you are using.
+ASDF 2 now achieves the same purpose with its builtin ASDF-OUTPUT-TRANSLATIONS,
+which should be easier to configure. Please stop using ASDF-BINARY-LOCATIONS,
+and instead use ASDF-OUTPUT-TRANSLATIONS. See the ASDF manual for details.
+In case you insist on preserving your previous A-B-L configuration, but
+do not know how to achieve the same effect with A-O-T, you may use function
+ASDF:ENABLE-ASDF-BINARY-LOCATIONS-COMPATIBILITY as documented in the manual;
+call that function where you would otherwise have loaded and configured A-B-L."))))
+
+
+  ;; run-shell-command from ASDF 2, lightly fixed from ASDF 1, copied from MK-DEFSYSTEM. Die!
+  (defun run-shell-command (control-string &rest args)
+    "PLEASE DO NOT USE. This function is not just DEPRECATED, but also dysfunctional.
+Please use UIOP:RUN-PROGRAM instead."
+    #-(and ecl os-windows)
+    (let ((command (apply 'format nil control-string args)))
+      (asdf-message "; $ ~A~%" command)
+      (let ((exit-code
+             (ignore-errors
+               (nth-value 2 (run-program command :force-shell t :ignore-error-status t
+                                         :output *verbose-out*)))))
+        (typecase exit-code
+          ((integer 0 255) exit-code)
+          (t 255))))
+    #+(and ecl os-windows)
+    (not-implemented-error "run-shell-command" "for ECL on Windows."))
+
+  ;; HOW do we get rid of variables??? With a symbol-macro that issues a warning?
+  ;; In Quicklisp 2015-05, cl-protobufs still uses it, but that should be fixed in next version.
+  (progn
+    (defvar *asdf-verbose* nil)) ;; backward-compatibility with ASDF2 only. Unused.
+
+  ;; Do NOT use in new code. NOT SUPPORTED.
+  ;; NB: When this goes away, remove the slot PROPERTY in COMPONENT.
+  ;; In Quicklisp 2014-05, it's still used by yaclml, amazon-ecs, blackthorn-engine, cl-tidy.
+  ;; See TODO for further cleanups required before to get rid of it.
+  (defgeneric component-property (component property))
+  (defgeneric (setf component-property) (new-value component property))
+
+  (defmethod component-property ((c component) property)
+    (cdr (assoc property (slot-value c 'properties) :test #'equal)))
+
+  (defmethod (setf component-property) (new-value (c component) property)
+    (let ((a (assoc property (slot-value c 'properties) :test #'equal)))
+      (if a
+          (setf (cdr a) new-value)
+          (setf (slot-value c 'properties)
+                (acons property new-value (slot-value c 'properties)))))
+    new-value)
+
+
+  ;; This method survives from ASDF 1, but really it is superseded by action-description.
+  (defgeneric explain (operation component)
+    (:documentation "Display a message describing an action.
+
+DEPRECATED. Use ASDF:ACTION-DESCRIPTION and/or ASDF::FORMAT-ACTION instead."))
+  (progn
+    (define-convenience-action-methods explain (operation component)))
+  (defmethod explain ((o operation) (c component))
+    (asdf-message (compatfmt "~&~@<; ~@;~A~:>~%") (action-description o c))))
+
+(with-asdf-deprecation (:style-warning "3.3")
+  (defun system-registered-p (name)
+    "DEPRECATED. Return a generalized boolean that is true if a system of given NAME was registered already.
+NAME is a system designator, to be normalized by COERCE-NAME.
+The value returned if true is a pair of a timestamp and a system object."
+    (if-let (system (registered-system name))
+      (cons (if-let (primary-system (registered-system (primary-system-name name)))
+              (component-operation-time 'define-op primary-system))
+            system)))
+
+  (defun require-system (system &rest keys &key &allow-other-keys)
+    "Ensure the specified SYSTEM is loaded, passing the KEYS to OPERATE, but do not update the
+system or its dependencies if it has already been loaded."
+    (declare (ignore keys))
+    (unless (component-loaded-p system)
+      (load-system system))))
+
+;;; This function is for backward compatibility with ECL only.
+#+ecl
+(with-asdf-deprecation (:style-warning "3.2" :warning "9999")
+  (defun make-build (system &rest args
+                     &key (monolithic nil) (type :fasl) (move-here nil move-here-p)
+                       prologue-code epilogue-code no-uiop
+                       prefix-lisp-object-files postfix-lisp-object-files extra-object-files
+                       &allow-other-keys)
+    (let* ((operation (asdf/bundle::select-bundle-operation type monolithic))
+           (move-here-path (if (and move-here
+                                    (typep move-here '(or pathname string)))
+                               (ensure-pathname move-here :namestring :lisp :ensure-directory t)
+                               (system-relative-pathname system "asdf-output/")))
+           (extra-build-args (remove-plist-keys
+                              '(:monolithic :type :move-here
+                                :prologue-code :epilogue-code :no-uiop
+                                :prefix-lisp-object-files :postfix-lisp-object-files
+                                :extra-object-files)
+                              args))
+           (build-system (if (subtypep operation 'image-op)
+                             (eval `(defsystem "asdf.make-build"
+                                      :class program-system
+                                      :source-file nil
+                                      :pathname ,(system-source-directory system)
+                                      :build-operation ,operation
+                                      :build-pathname ,(subpathname move-here-path
+                                                                    (file-namestring (first (output-files operation system))))
+                                      :depends-on (,(coerce-name system))
+                                      :prologue-code ,prologue-code
+                                      :epilogue-code ,epilogue-code
+                                      :no-uiop ,no-uiop
+                                      :prefix-lisp-object-files ,prefix-lisp-object-files
+                                      :postfix-lisp-object-files ,postfix-lisp-object-files
+                                      :extra-object-files ,extra-object-files
+                                      :extra-build-args ,extra-build-args))
+                             system))
+           (files (output-files operation build-system)))
+      (operate operation build-system)
+      (if (or move-here
+              (and (null move-here-p) (member operation '(program-op image-op))))
+          (loop :with dest-path = (resolve-symlinks* (ensure-directories-exist move-here-path))
+            :for f :in files
+            :for new-f = (make-pathname :name (pathname-name f)
+                                        :type (pathname-type f)
+                                        :defaults dest-path)
+            :do (rename-file-overwriting-target f new-f)
+            :collect new-f)
+          files))))
+;;;; ---------------------------------------------------------------------------
+;;;; Handle ASDF package upgrade, including implementation-dependent magic.
+
+(uiop/package:define-package :asdf/interface
+  (:nicknames :asdf :asdf-utilities)
+  (:recycle :asdf/interface :asdf)
+  (:unintern
+   #:loaded-systems ; makes for annoying SLIME completion
+   #:output-files-for-system-and-operation) ; ASDF-BINARY-LOCATION function we use to detect ABL
+  (:use :uiop/common-lisp :uiop :asdf/upgrade :asdf/session
+   :asdf/component :asdf/system :asdf/system-registry :asdf/find-component
+   :asdf/operation :asdf/action :asdf/lisp-action
+   :asdf/output-translations :asdf/source-registry
+   :asdf/forcing :asdf/plan :asdf/operate :asdf/find-system :asdf/parse-defsystem
+   :asdf/bundle :asdf/concatenate-source
+   :asdf/backward-internals :asdf/backward-interface :asdf/package-inferred-system)
+  ;; Note: (1) we are NOT automatically reexporting everything from previous packages.
+  ;; (2) we only reexport UIOP functionality when backward-compatibility requires it.
+  (:export
+   #:defsystem #:find-system #:load-asd #:locate-system #:coerce-name
+   #:primary-system-name #:primary-system-p
+   #:oos #:operate #:make-plan #:perform-plan #:sequential-plan
+   #:system-definition-pathname
+   #:search-for-system-definition #:find-component #:component-find-path
+   #:compile-system #:load-system #:load-systems #:load-systems*
+   #:require-system #:test-system #:clear-system
+   #:operation #:make-operation #:find-operation
+   #:upward-operation #:downward-operation #:sideway-operation #:selfward-operation
+                      #:non-propagating-operation
+   #:build-op #:make
+   #:load-op #:prepare-op #:compile-op
+   #:prepare-source-op #:load-source-op #:test-op #:define-op
+   #:feature #:version #:version-satisfies #:upgrade-asdf
+   #:implementation-identifier #:implementation-type #:hostname
+   #:component-depends-on ; backward-compatible name rather than action-depends-on
+   #:input-files #:additional-input-files
+   #:output-files #:output-file #:perform #:perform-with-restarts
+   #:operation-done-p #:explain #:action-description #:component-sideway-dependencies
+   #:needed-in-image-p
+   #:bundle-op #:monolithic-bundle-op #:precompiled-system #:compiled-file #:bundle-system
+   #:program-system
+   #:basic-compile-bundle-op #:prepare-bundle-op
+   #:compile-bundle-op #:load-bundle-op #:monolithic-compile-bundle-op #:monolithic-load-bundle-op
+   #:lib-op #:dll-op #:deliver-asd-op #:program-op #:image-op
+   #:monolithic-lib-op #:monolithic-dll-op #:monolithic-deliver-asd-op
+   #:concatenate-source-op
+   #:load-concatenated-source-op
+   #:compile-concatenated-source-op
+   #:load-compiled-concatenated-source-op
+   #:monolithic-concatenate-source-op
+   #:monolithic-load-concatenated-source-op
+   #:monolithic-compile-concatenated-source-op
+   #:monolithic-load-compiled-concatenated-source-op
+   #:operation-monolithic-p
+   #:required-components
+   #:component-loaded-p
+   #:component #:parent-component #:child-component #:system #:module
+   #:file-component #:source-file #:c-source-file #:java-source-file
+   #:cl-source-file #:cl-source-file.cl #:cl-source-file.lsp
+   #:static-file #:doc-file #:html-file
+   #:file-type #:source-file-type
+   #:register-preloaded-system #:sysdef-preloaded-system-search
+   #:register-immutable-system #:sysdef-immutable-system-search
+   #:package-inferred-system #:register-system-packages
+   #:component-children
+   #:component-children-by-name
+   #:component-pathname
+   #:component-relative-pathname
+   #:component-name
+   #:component-version
+   #:component-parent
+   #:component-system
+   #:component-encoding
+   #:component-external-format
+   #:system-description
+   #:system-long-description
+   #:system-author
+   #:system-maintainer
+   #:system-license
+   #:system-licence
+   #:system-version
+   #:system-source-file
+   #:system-source-directory
+   #:system-relative-pathname
+   #:system-homepage
+   #:system-mailto
+   #:system-bug-tracker
+   #:system-long-name
+   #:system-source-control
+   #:map-systems
+   #:system-defsystem-depends-on
+   #:system-depends-on
+   #:system-weakly-depends-on
+   #:*system-definition-search-functions*   ; variables
+   #:*central-registry*
+   #:*compile-file-warnings-behaviour*
+   #:*compile-file-failure-behaviour*
+   #:*resolve-symlinks*
+   #:*verbose-out*
+   #:asdf-version
+   #:compile-condition #:compile-file-error #:compile-warned-error #:compile-failed-error
+   #:compile-warned-warning #:compile-failed-warning
+   #:error-name
+   #:error-pathname
+   #:load-system-definition-error
+   #:error-component #:error-operation
+   #:system-definition-error
+   #:missing-component
+   #:missing-component-of-version
+   #:missing-dependency
+   #:missing-dependency-of-version
+   #:circular-dependency        ; errors
+   #:duplicate-names #:non-toplevel-system #:non-system-system #:bad-system-name #:system-out-of-date
+   #:package-inferred-system-missing-package-error
+   #:operation-definition-warning #:operation-definition-error
+   #:try-recompiling ; restarts
+   #:retry
+   #:accept
+   #:coerce-entry-to-directory
+   #:remove-entry-from-registry
+   #:clear-configuration-and-retry
+   #:*encoding-detection-hook*
+   #:*encoding-external-format-hook*
+   #:*default-encoding*
+   #:*utf-8-external-format*
+   #:clear-configuration
+   #:*output-translations-parameter*
+   #:initialize-output-translations
+   #:disable-output-translations
+   #:clear-output-translations
+   #:ensure-output-translations
+   #:apply-output-translations
+   #:compile-file*
+   #:compile-file-pathname*
+   #:*warnings-file-type* #:enable-deferred-warnings-check #:disable-deferred-warnings-check
+   #:enable-asdf-binary-locations-compatibility
+   #:*default-source-registries*
+   #:*source-registry-parameter*
+   #:initialize-source-registry
+   #:compute-source-registry
+   #:clear-source-registry
+   #:ensure-source-registry
+   #:process-source-registry
+   #:registered-system #:registered-systems #:already-loaded-systems
+   #:resolve-location
+   #:asdf-message
+   #:*user-cache*
+   #:user-output-translations-pathname
+   #:system-output-translations-pathname
+   #:user-output-translations-directory-pathname
+   #:system-output-translations-directory-pathname
+   #:user-source-registry
+   #:system-source-registry
+   #:user-source-registry-directory
+   #:system-source-registry-directory
+
+   ;; The symbols below are all DEPRECATED, do not use. To be removed in a further release.
+   #:*asdf-verbose* #:run-shell-command
+   #:component-load-dependencies #:system-registered-p #:package-system
+   #+ecl #:make-build
+   #:operation-on-warnings #:operation-on-failure #:operation-error
+   #:compile-failed #:compile-warned #:compile-error
+   #:module-components #:component-property #:traverse))
+;;;; ---------------------------------------------------------------------------
+;;;; ASDF-USER, where the action happens.
+
+(uiop/package:define-package :asdf/user
+  (:nicknames :asdf-user)
+  ;; NB: releases before 3.1.2 this :use'd only uiop/package instead of uiop below.
+  ;; They also :use'd uiop/common-lisp, that reexports common-lisp and is not included in uiop.
+  ;; ASDF3 releases from 2.27 to 2.31 called uiop asdf-driver and asdf/foo uiop/foo.
+  ;; ASDF1 and ASDF2 releases (2.26 and earlier) create a temporary package
+  ;; that only :use's :cl and :asdf
+  (:use :uiop/common-lisp :uiop :asdf/interface))
+;;;; -----------------------------------------------------------------------
+;;;; ASDF Footer: last words and cleanup
+
+(uiop/package:define-package :asdf/footer
+  (:recycle :asdf/footer :asdf)
+  (:use :uiop/common-lisp :uiop
+        :asdf/system ;; used by ECL
+        :asdf/upgrade :asdf/system-registry :asdf/operate :asdf/bundle)
+  ;; Happily, all those implementations all have the same module-provider hook interface.
+  #+(or abcl clasp cmucl clozure ecl mezzano mkcl sbcl)
+  (:import-from #+abcl :sys #+(or clasp cmucl ecl) :ext #+clozure :ccl #+mkcl :mk-ext #+sbcl sb-ext #+mezzano :sys.int
+                #:*module-provider-functions*
+                #+ecl #:*load-hooks*)
+  #+(or clasp mkcl) (:import-from :si #:*load-hooks*))
+
+(in-package :asdf/footer)
+
+;;;; Register ASDF itself and all its subsystems as preloaded.
+(with-upgradability ()
+  (dolist (s '("asdf" "uiop" "asdf-package-system"))
+    ;; Don't bother with these system names, no one relies on them anymore:
+    ;; "asdf-utils" "asdf-bundle" "asdf-driver" "asdf-defsystem"
+    (register-preloaded-system s :version *asdf-version*)))
+
+
+;;;; Hook ASDF into the implementation's REQUIRE and other entry points.
+#+(or abcl clasp clisp clozure cmucl ecl mezzano mkcl sbcl)
+(with-upgradability ()
+  ;; Hook into CL:REQUIRE.
+  #-clisp (pushnew 'module-provide-asdf *module-provider-functions*)
+  #+clisp (if-let (x (find-symbol* '#:*module-provider-functions* :custom nil))
+            (eval `(pushnew 'module-provide-asdf ,x)))
+
+  #+(or clasp ecl mkcl)
+  (progn
+    (pushnew '("fasb" . si::load-binary) *load-hooks* :test 'equal :key 'car)
+
+    #+os-windows
+    (unless (assoc "asd" *load-hooks* :test 'equal)
+      (appendf *load-hooks* '(("asd" . si::load-source))))
+
+    ;; Wrap module provider functions in an idempotent, upgrade friendly way
+    (defvar *wrapped-module-provider* (make-hash-table))
+    (setf (gethash 'module-provide-asdf *wrapped-module-provider*) 'module-provide-asdf)
+    (defun wrap-module-provider (provider name)
+      (let ((results (multiple-value-list (funcall provider name))))
+        (when (first results) (register-preloaded-system (coerce-name name)))
+        (values-list results)))
+    (defun wrap-module-provider-function (provider)
+      (ensure-gethash provider *wrapped-module-provider*
+                      (constantly
+                       #'(lambda (module-name)
+                           (wrap-module-provider provider module-name)))))
+    (setf *module-provider-functions*
+          (mapcar #'wrap-module-provider-function *module-provider-functions*))))
+
+#+cmucl ;; Hook into the CMUCL herald.
+(with-upgradability ()
+  (defun herald-asdf (stream)
+    (format stream "    ASDF ~A" (asdf-version)))
+  (setf (getf ext:*herald-items* :asdf) '(herald-asdf)))
+
+
+;;;; Done!
+(with-upgradability ()
+  #+allegro ;; restore *w-o-n-r-c* setting as saved in uiop/common-lisp
+  (when (boundp 'excl:*warn-on-nested-reader-conditionals*)
+    (setf excl:*warn-on-nested-reader-conditionals* uiop/common-lisp::*acl-warn-save*))
+
+  ;; Advertise the features we provide.
+  (dolist (f '(:asdf :asdf2 :asdf3 :asdf3.1 :asdf3.2 :asdf3.3)) (pushnew f *features*))
+
+  ;; Provide both lowercase and uppercase, to satisfy more people, especially LispWorks users.
+  (provide "asdf") (provide "ASDF")
+
+  ;; Finally, call a function that will cleanup in case this is an upgrade of an older ASDF.
+  (cleanup-upgraded-asdf))
+
+(when *load-verbose*
+  (asdf-message ";; ASDF, version ~a~%" (asdf-version)))
diff --git a/swh/loader/core/tests/test_loader.py b/swh/loader/core/tests/test_loader.py
--- a/swh/loader/core/tests/test_loader.py
+++ b/swh/loader/core/tests/test_loader.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2018-2021  The Software Heritage developers
+# Copyright (C) 2018-2022  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
@@ -15,6 +15,7 @@
     SENTRY_ORIGIN_URL_TAG_NAME,
     SENTRY_VISIT_TYPE_TAG_NAME,
     BaseLoader,
+    ContentLoader,
     DVCSLoader,
 )
 from swh.loader.core.metadata_fetchers import MetadataFetcherProtocol
@@ -306,10 +307,12 @@
     assert save_path == expected_save_path
 
 
-def _check_load_failure(caplog, loader, exc_class, exc_text, status="partial"):
+def _check_load_failure(
+    caplog, loader, exc_class, exc_text, status="partial", origin=ORIGIN
+):
     """Check whether a failed load properly logged its exception, and that the
     snapshot didn't get referenced in storage"""
-    assert isinstance(loader, DVCSLoader)  # was implicit so far
+    assert isinstance(loader, (DVCSLoader, ContentLoader))  # was implicit so far
     for record in caplog.records:
         if record.levelname != "ERROR":
             continue
@@ -319,11 +322,12 @@
         assert isinstance(exc, exc_class)
         assert exc_text in exc.args[0]
 
-    # Check that the get_snapshot operation would have succeeded
-    assert loader.get_snapshot() is not None
+    if isinstance(loader, DVCSLoader):
+        # Check that the get_snapshot operation would have succeeded
+        assert loader.get_snapshot() is not None
 
     # And confirm that the visit doesn't reference a snapshot
-    visit = assert_last_visit_matches(loader.storage, ORIGIN.url, status)
+    visit = assert_last_visit_matches(loader.storage, origin.url, status)
     if status != "partial":
         assert visit.snapshot is None
         # But that the snapshot didn't get loaded
@@ -503,3 +507,92 @@
     sentry_tags = sentry_events[0]["tags"]
     assert sentry_tags.get(SENTRY_ORIGIN_URL_TAG_NAME) == ORIGIN.url
     assert sentry_tags.get(SENTRY_VISIT_TYPE_TAG_NAME) == DummyLoader.visit_type
+
+
+CONTENT_MIRROR = "https://common-lisp.net"
+CONTENT_URL = f"{CONTENT_MIRROR}/project/asdf/archives/asdf-3.3.5.lisp"
+
+
+def test_content_loader_missing_field(swh_storage):
+    origin = Origin(CONTENT_URL)
+    with pytest.raises(ValueError, match="Mandatory field"):
+        ContentLoader(swh_storage, origin.url)
+
+
+def test_content_loader_404(caplog, swh_storage, requests_mock_datadir):
+    unknown_origin = Origin(f"{CONTENT_MIRROR}/project/asdf/archives/unknown.lisp")
+    loader = ContentLoader(
+        swh_storage, unknown_origin.url, integrity="sha256-unusedfornow"
+    )
+    result = loader.load()
+
+    assert result == {"status": "uneventful"}
+
+    _check_load_failure(
+        caplog,
+        loader,
+        NotFound,
+        "Unknown origin",
+        status="not_found",
+        origin=unknown_origin,
+    )
+
+
+def test_content_loader_404_with_fallback(caplog, swh_storage, requests_mock_datadir):
+    unknown_origin = Origin(f"{CONTENT_MIRROR}/project/asdf/archives/unknown.lisp")
+    fallback_url_ko = f"{CONTENT_MIRROR}/project/asdf/archives/unknown2.lisp"
+    loader = ContentLoader(
+        swh_storage,
+        unknown_origin.url,
+        fallback_urls=[fallback_url_ko],
+        integrity="sha256-unusedfornow",
+    )
+    result = loader.load()
+
+    assert result == {"status": "uneventful"}
+
+    _check_load_failure(
+        caplog,
+        loader,
+        NotFound,
+        "Unknown origin",
+        status="not_found",
+        origin=unknown_origin,
+    )
+
+
+def test_content_loader_ok_with_fallback(caplog, swh_storage, requests_mock_datadir):
+    dead_origin = Origin(f"{CONTENT_MIRROR}/dead-origin-url")
+    fallback_url_ok = CONTENT_URL
+    fallback_url_ko = f"{CONTENT_MIRROR}/project/asdf/archives/unknown2.lisp"
+
+    loader = ContentLoader(
+        swh_storage,
+        dead_origin.url,
+        fallback_urls=[fallback_url_ok, fallback_url_ko],
+        integrity="sha256-0HwaD0oDEfgwRDj0ooiVOxXnoZG1qYLDiwq4EWP2zdc=",
+    )
+    result = loader.load()
+
+    assert result == {"status": "eventful"}
+
+
+def test_content_loader_ok_simple(swh_storage, requests_mock_datadir):
+    origin = Origin(CONTENT_URL)
+    loader = ContentLoader(
+        swh_storage,
+        origin.url,
+        integrity="sha256-0HwaD0oDEfgwRDj0ooiVOxXnoZG1qYLDiwq4EWP2zdc=",
+    )
+    result = loader.load()
+
+    assert result == {"status": "eventful"}
+
+    visit_status = assert_last_visit_matches(
+        swh_storage, origin.url, status="full", type="content"
+    )
+    assert visit_status.snapshot is not None
+
+    result2 = loader.load()
+
+    assert result2 == {"status": "uneventful"}