bug#61521: "default" is now the first item returned from (font-faces), breaking various code.

[Eli Zaretskii <eliz@gnu.org>]

> From: Brennan Vincent <brennan@umanwizard.com>
> Date: Wed, 15 Feb 2023 09:01:31 -0500
> Cc: 61521@debbugs.gnu.org
> 
> > On Feb 15, 2023, at 07:58, Eli Zaretskii <eliz@gnu.org> wrote:
> > 
> > 
> >> 
> >> Date: Tue, 14 Feb 2023 19:31:30 -0500
> >> From: Brennan Vincent <brennan@umanwizard.com>
> >> 
> >> 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)))
> > 
> > That comment is obsolete and needs to be changed (and the call to
> > nreverse should perhaps be removed).
> 
> If the order returned by face-list is not guaranteed, then why does it do sorting at all?

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.

Gregory, any counter-arguments?