Subject: bug#57639: [PATCH] Add new command 'toggle-theme'

From: Stefan Monnier <[email-masked]>
Date: Thu, 20 Oct 2022 13:04:28 -0400

>>>> We could arrange for `autoload/loaddefs-gen` to recognize `deftheme` and
>>>> add the directory containing the file containing this `deftheme` to the
>>>> `custom-theme-load-path`.
>>> If this is possible I think this would be a nice idea.
>> It should be easy to do.
> Sadly I am stumped on how this could be done, as I have little
> experience with the bootstrapping process.  Could you give me a few pointers?

I was thinking of something like the patch below.

        Stefan

diff --git a/lisp/emacs-lisp/loaddefs-gen.el b/lisp/emacs-lisp/loaddefs-gen.el
index ecc5f7e47bd..a07d0e9ad61 100644
--- a/lisp/emacs-lisp/loaddefs-gen.el
+++ b/lisp/emacs-lisp/loaddefs-gen.el
@@ -286,8 +286,16 @@ loaddefs-generate--make-autoload
      ;; Extract theme properties.
      ((eq car 'deftheme)
       (let* ((name (car-safe (cdr-safe form)))
-	     (props (nthcdr 3 form)))
-	`(put ',name 'theme-properties (list ,@props))))
+	     (props (nthcdr 3 form))
+	     (dir (file-name-directory file)))
+	`(progn
+	   (add-to-list 'custom-theme-load-path
+	                ,(if dir 
+	                     `(expand-file-name ,dir
+	                                        (file-name-directory
+	                                         (macroexp-file-name)))
+	                   `(file-name-directory (macroexp-file-name))))
+	   (put ',name 'theme-properties (list ,@props)))))
 
      ((eq car 'defgroup)
       ;; In Emacs this is normally handled separately by cus-dep.el, but for