bug#70136: 30.0.50; compilation-mode [was: comint-mode] doesn't call hack-dir-local-variables-non-file-buffer

[Eli Zaretskii]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: arstoffel@gmail.com,  70136@debbugs.gnu.org
> Date: Wed, 17 Apr 2024 08:59:50 -0400
> 
> >> Also, I'm not seeing why "That's not the same".
> >
> > Because introducing a new feature is qualitatively different: it can
> > have no backward-compatibility problems, since no one can possibly
> > have existing customizations for it.
> 
> That commit I referred to had AFAICT the same effect as the one
> discussed here: it made some modes (diff-mode, log-edit-mode, and a few
> more) obey dir-locals whereas they didn't before.
> And dir-locals existed since several years before that.
> 
> Why would it be more likely for them to have .dir-locals which
> accidentally affect grep-mode than diff-mode/log-edit-mode/...?
> 
> AFAICT it risked the exact same backward compatibility problems.

So we should risk it again?

> >> Should we add a message like
> >> "ignoring dir-locals.  See 
> >> obey-dir-local-variables-in-all-non-file-buffers"?
> > The time for April 1 jokes has come and passed this year, no? ;-)
> 
> I'm quite serious.  From where I stand, I think most users would
> want to enable this feature in they have a situation where it affects
> the behavior of Emacs.

If you are right, we will be able to make this on by default in Emacs
31 (assuming we introduce the opt-in feature in Emacs 30, that is: no
one has yet shown the code, so we are discussing a highly theoretical
feature).