bug#65414: save-some-buffers-functions are unexpectedly called when save-some-buffers pred is non-nil

[Eli Zaretskii <eliz@gnu.org>]

> Cc: jonas@bernoul.li
> Date: Sun, 20 Aug 2023 21:06:54 -0700
> From:  Joseph Turner via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> Functions which are added to save-some-buffers-functions are always
> called when save-some-buffers runs, even when a PRED argument is
> specified. This leads to unexpected behavior when PRED is intended to
> limit saving buffers to a specific set of file buffers, as in Magit's
> magit-save-repository-buffers function.
> 
> abbrev--possibly-save is added to save-some-buffers-functions by default
> now, so whenever magit-save-repository-buffers runs, Emacs prompts to
> save unsaved abbrevs (as well any other functions in the list).

Why is asking whether to save the abbrevs a problem in the case of
magit-save-repository-buffers?

And are you saying that before the change which added
save-some-buffers-functions, Emacs was not saving the abbrevs when
save-some-buffers was called?  If so, in what Emacs version was this
so?

> I propose that we pass along the PRED argument of save-some-buffers to
> each of save-some-buffers-functions, allowing them to determine what is
> appropriate to do. Alternatively, we could pass along the return value
> of files--buffers-needing-to-be-saved, which is a list of buffers.

We need a better understanding of the situation before we can discuss
solutions, so please fill-in the blanks outlined above.  (The solution
you propose is not very backward-compatible, so probably not
acceptable anyway, as Emacs 29 was already released with the current
code.  But let's defer this discussion until the issue is more clear.)