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

[Eli Zaretskii]

> From: Joseph Turner <joseph@breatheoutbreathe.in>
> Cc: 65414@debbugs.gnu.org, jonas@bernoul.li
> Date: Sat, 26 Aug 2023 00:32:23 -0700
> 
> 
> > In any case, not calling save-some-buffers-functions when PRED is
> > non-nil is not something we can do, as that would be an incompatible
> > behavior change.  We could perhaps add PRED to the arguments with
> > which save-some-buffers-functions are called, as an optional argument.
> > Would that be satisfactory?
> 
> Yes, that would solve the interference between Magit and hyperdrive.el.
> 
> See patch.

Hmm... but how to make this change backward-compatible?  I mean, if
there's some function out there that is used in
save-some-buffers-functions, and it was written to accept only 2
arguments, we cannot safely call it with 3 arguments, can we?

Stefan, do we have any way of doing that without causing errors?

If not, perhaps the way forward is to bind some variable around the
call to these functions, whose value will be PRED?