bug#64048: 30.0.50; global-display-line-numbers-mode has no easy way to set modes where it is enabled

[Eli Zaretskii]

> From: Ihor Radchenko <yantar92@posteo.net>
> Cc: 64048@debbugs.gnu.org
> Date: Tue, 13 Jun 2023 16:09:30 +0000
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> that will also define `display-line-numbers-modes' variable that
> >> controls where the global mode is enabled/disabled?
> >> 
> >> Maybe it should even be the default in `define-globalized-minor-mode'
> >> when :predicate is not defined.
> >
> > I think it's too late for such changes, because it will definitely
> > break someone's setup.
> 
> May you please elaborate?
> 
> IMHO, the only way honouring `global-foo-modes' variable will break
> someone's setup is when somebody sets `global-foo-modes' (which has no
> effect now) and expects that there will be no effect in future as well.

I have enough gray hair to know that any such changes break something.

This mode has been with us since Emacs 26, so we cannot make such
changes after so much time.  Especially since the problem, if there is
a problem, is minor at best.

Sorry.