bug#69983: Use category for display-buffer-alist

[Eli Zaretskii <eliz@gnu.org>]

> From: Juri Linkov <juri@linkov.net>
> Cc: rudalics@gmx.at,  69983@debbugs.gnu.org
> Date: Fri, 12 Apr 2024 09:37:10 +0300
> 
> >> There is already the option display-buffer-alist.
> >
> > Which I think is not appropriate for customizing what warnings.el
> > does, for the reasons I explained above.
> 
> As you can see in the Subject, the whole point of this bug report is to
> add a category to display-buffer calls, so displaying the warning buffer
> can be customized by the existing option 'display-buffer-alist'.

I don't object to adding the category to display-buffer-alist.  I
object to using that as a means to control what warnings.el does.  In
particular, as I already pointed out, some warnings don't pop up a
window with a special buffer, so if the users use display-buffer-alist
for controlling warnings.el, they will be disappointed in some cases.

> Adding hundreds of separate options for every display-buffer call
> makes no sense.

Adding hundreds of separate options indeed doesn't make sense, but I
suggested to add just one.  In addition:

  . you haven't addressed my comments that currently we don't even
    document that warnings.el uses display-buffer (and neither do I
    think we _should_ document that);
  . you haven't explained what kind of behavior change would you like
    to make in how warnings.el displays the warnings, without which
    I'm not even sure I understand the intended change of behavior