bug#55579: 29.0.50; Abbrevs not saved on exit anymore

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Cc: 55579@debbugs.gnu.org
> Date: Wed, 25 May 2022 09:37:20 +0300
> 
> >> > Save abbrevs in ~/.emacs.d/abbrev_defs?
> >>
> >> BTW, I noticed that ~/.emacs.d/abbrev_defs
> >> is visited without font-locking.  Here's the fix:
> >
> > Won't that make loading abbrevs slower and more expensive?  that file
> > is normally not edited interactively, only if the user explicitly
> > wants to do so.  So why is font-lock in it important?
> 
> This is part of recent efforts to add modes to .emacs.d files.
> So far we added the mode tag to ~/.emacs.d/bookmarks, ~/.emacs.d/tramp,
> ~/.emacs.d/.emacs.desktop, ~/.emacs.d/network-security.data,
> ~/.emacs.d/places, ~/.emacs.d/projects.  But mode is still missing
> in ~/.emacs.d/abbrev_defs and ~/.emacs.d/recentf.

We don't need to do that for all of the files, only for files that are
frequently (or always) visited or edited interactively by users.  So
I'm asking this question specifically for abbrev_defs, not for all the
other files there: why do we need this, and how significant is the
reason?