bug#64487: 29.0.92; Another tree-sitter warning inside Custom

[Dmitry Gutov]

On 26/02/2024 18:49, Eli Zaretskii wrote:
> > Date: Mon, 26 Feb 2024 18:25:33 +0200
> > Cc: 64487@debbugs.gnu.org
> > From: Dmitry Gutov <dmitry@gutov.dev>
> >
> > On 06/07/2023 12:12, Eli Zaretskii wrote:
> > > > Date: Thu, 06 Jul 2023 14:56:44 +0800
> > > > From:  Po Lu via "Bug reports for GNU Emacs,
> > > >    the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> > > >
> > > > Type M-x customize RET.  Click Programming and then Languages.  A
> > > > *Warnings* buffer will be displayed containing the following message:
> > > >
> > > >     Warning (treesit): Cannot activate tree-sitter, because language
> > > >     grammar for ruby is unavailable (not-found): (libtree-sitter-ruby
> > > >     libtree-sitter-ruby.0 libtree-sitter-ruby.0.0 libtree-sitter-ruby.so
> > > >     libtree-sitter-ruby.so.0 libtree-sitter-ruby.so.0.0) No such file or
> > > >     directory
> > >
> > > When you customize a group, Custom loads all the packages that belong
> > > to the group.  So in this case it loads ruby-ts-mode, and you get the
> > > warning.
> >
> > Which was never a problem before when simply loading a package didn't
> > alter auto-mode-alist.
>
> You want to start that old dispute again?  I didn't expect you to
> change your opinions, and you shouldn't expect me to change mine.  So
> why restart that?

I remember you saying that it was a question which is settled until any 
other problems come up. Isn't this an example of such problem?

> > Do I understand it right that performing the simple steps that Po Lu
> > outlined would silently assign ruby-ts-mode to *.rb files? And a bunch
> > of other such modes that get loaded as well. But only until the end of
> > the session.
>
> Could be, I didn't try.  If that's what happens, patches to avoid such
> a long-lasting effect, without changing what happens when the package
> is loaded outside of the Customize context, will be welcome.

I don't have any solutions to suggest except holding to the principle 
that simply loading a package has as few side-effects as possible. Which 
would mean reverting your earlier decision.