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Subject: |
"default" is now the first item returned from (font-faces), breaking various code. |
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Date: |
Tue, 14 Feb 2023 19:31:30 -0500 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.7.1 |
Various code seems to expect "default" to be the /last/ item in the list
returned by that function, not the first. For example, this comment in faces.el:
;; The `reverse' is so that `default' goes first.
(dolist (face (nreverse (face-list)))
Also, org-html-htmlize-generate-css does not work when default comes first in
the list (as it skips processing all fonts after default).
I am not sure why this was changed and if the change was intentional, but it can
be fixed by changing the "<" to a ">" in the last line of face-list, so I
suspect it might have been a mistake.
diff --git lisp/faces.el lisp/faces.el
index 4933b495a6c..e998dc504e5 100644
--- lisp/faces.el
+++ lisp/faces.el
@@ -199,7 +199,7 @@ face-list
(maphash (lambda (face spec)
(push `(,(car spec) . ,face) faces))
face--new-frame-defaults)
- (mapcar #'cdr (sort faces (lambda (f1 f2) (< (car f1) (car f2)))))))
+ (mapcar #'cdr (sort faces (lambda (f1 f2) (> (car f1) (car f2)))))))
(defun make-face (face)
"Define a new face with name FACE, a symbol.
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--- Begin Message ---
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Subject: |
Re: bug#61521: "default" is now the first item returned from (font-faces), breaking various code. |
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Date: |
Fri, 17 Feb 2023 10:29:39 +0200 |
> Date: Wed, 15 Feb 2023 11:19:54 -0500
> Cc: 61521@debbugs.gnu.org
> From: Brennan Vincent <brennan@umanwizard.com>
>
> > Good question. AFAICT, the sorting was added when we switched from
> > storing faces in alists to storing them in hash tables. It probably
> > sorted faces to be more compatible with what face-list returned before
> > the switch to hash table. So I suspect the order we have now is
> > simply a bug, and we do need to change the order of sorting to get
> > back the original order.
>
> I tend to agree. Sorry for not explaining this reasoning more fully in my
> original message.
>
> Here's what I suspect happened (not 100% sure, it's just a theory):
>
> (1) Initially set of faces was stored as a list, so it was naturally
> maintained
> in the inverse order that things were added to it (thus default would be at
> the
> end).
>
> (2) Now faces are stored in a hash table whose key is the face and whose value
> contains various pieces of data, including the face ID.
>
> (3) This face ID is allocated in increasing order (see e.g. this code in
> xfaces.c:
> Lisp_Object face_id = make_fixnum (next_lface_id);
> lface_id_to_name[next_lface_id] = face;
> Fput (face, Qface, face_id);
> ++next_lface_id;
>
> (4) Thus, `face-list` and `frame-face-alist` sorted the faces by face ID in
> order to maintain the old ordering behavior. However, the author accidentally
> inverted the comparison when doing so.
>
>
> > Gregory, any counter-arguments?
No further comments, so I've now installed the proposed changes on the
emacs-29 branch, and I'm boldly closing this bug as done.
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