bug#39823: 26.3; update-directory-autoloads regression from Emacs 26 to Emacs 27

[Maxim Cournoyer <maxim.cournoyer@gmail.com>]

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Hello Noam,

Noam Postavsky <npostavs@gmail.com> writes:

> Maxim Cournoyer <maxim.cournoyer@gmail.com> writes:
>
>> (defun update-directory-autoloads (&rest dirs)
>>
>> I don't see how &key can be combined with &rest without potentially
>> causing problems.
>
> You can check if the first arg is a keyword like
> :generated-autoload-file (which can't be a directory, since it's not a
> string), and if it is, then handle the second arg specially.

I've given this idea a try with the attached patch.  For some reason I
can't seem to simply eval the definition to test it (Debugger
entered--Lisp error: (void-function byte-compile-info-string).  I'm
rebuilding Emacs with the change right now.

Consider it untested for now.


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From 227fea1c404783b93540a1ca2c4c838f9c86ebba Mon Sep 17 00:00:00 2001
From: Maxim Cournoyer <maxim.cournoyer@gmail.com>
Date: Sun, 21 Jun 2020 23:09:53 -0400
Subject: [PATCH] lisp: autoload.el: Add a keyword argument to
 update-directory-autoloads.

This provides a way to explicitly specify the GENERATED-AUTOLOAD-FILE
file name to use for the generated autoload definitions, which is more
convenient when using lexical scoping.  Previously, the user had to
use dynamic scoping and bind the variable before calling
`update-directory-autoloads'.  This was discussed in
<https://bugs.gnu.org/39823>.

* lisp/emacs-lisp/autoload.el (update-directory-autoloads): Define the
procedure using cl-defun, and add a :generated-autoload-file keyword
argument.  Update doc.  Honor :generated-autoload-file keyword
argument, and remove it and its associated value from DIRS, if
present.
---
 lisp/emacs-lisp/autoload.el | 30 +++++++++++++++++++++++++-----
 1 file changed, 25 insertions(+), 5 deletions(-)

diff --git a/lisp/emacs-lisp/autoload.el b/lisp/emacs-lisp/autoload.el
index ede4edcd57..423cc67e99 100644
--- a/lisp/emacs-lisp/autoload.el
+++ b/lisp/emacs-lisp/autoload.el
@@ -32,6 +32,8 @@
 
 (require 'lisp-mode)			;for `doc-string-elt' properties.
 (require 'lisp-mnt)
+(require 'seq)
+
 (eval-when-compile (require 'cl-lib))
 
 (defvar generated-autoload-file nil
@@ -1023,7 +1025,10 @@ removes any prior now out-of-date autoload entries."
   (delete-region begin (point)))
 
 ;;;###autoload
-(defun update-directory-autoloads (&rest dirs)
+(cl-defun update-directory-autoloads (&rest dirs
+                                            &key (generated-autoload-file
+                                                  generated-autoload-file)
+                                            &allow-other-keys)
   "Update autoload definitions for Lisp files in the directories DIRS.
 In an interactive call, you must give one argument, the name of a
 single directory.  In a call from Lisp, you can supply multiple
@@ -1035,11 +1040,26 @@ directory or directories specified.
 In an interactive call, prompt for a default output file for the
 autoload definitions, and temporarily bind the variable
 `generated-autoload-file' to this value.  When called from Lisp,
-use the existing value of `generated-autoload-file'.  If any Lisp
-file binds `generated-autoload-file' as a file-local variable,
-write its autoloads into the specified file instead."
+use the existing value of `generated-autoload-file'.
+Alternatively, `generated-autoload-file' can also be provided
+using a Common Lisp style keyword ':generated-autoload-file'
+argument.  If any Lisp file binds `generated-autoload-file' as a
+file-local variable, write its autoloads into the specified file
+instead."
   (interactive "DUpdate autoloads from directory: ")
-  (let* ((files-re (let ((tmp nil))
+  (let* (;; Honor the :generated-autoload-file keyword argument.
+         (generated-autoload-file-arg (seq-position
+                                       dirs ':generated-autoload-file))
+         (generated-autoload-file (if generated-autoload-file-arg
+                                      (elt dirs
+                                           (1+ generated-autoload-file-arg))
+                                    generated-autoload-file))
+         ;; Cleanup dirs from such keyword argument, if any.
+         (dirs (if generated-autoload-file-arg
+                   (delete generated-autoload-file
+                           (delete ':generated-autoload-file dirs))
+                 dirs))
+         (files-re (let ((tmp nil))
 		     (dolist (suf (get-load-suffixes))
                        ;; We don't use module-file-suffix below because
                        ;; we don't want to depend on whether Emacs was
-- 
2.26.2


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Thank you!

Maxim