bug#69187: 29.2; Poor compatibility in align.el

[Eli Zaretskii <eliz@gnu.org>]

> From: Ikumi Keita <ikumi@ikumi.que.jp>
> cc: 69187@debbugs.gnu.org, John Wiegley <johnw@gnu.org>
> Comments: In-reply-to Eli Zaretskii <eliz@gnu.org>
>    message dated "Sat, 06 Apr 2024 09:21:18 +0300."
> Date: Sat, 06 Apr 2024 18:30:49 +0900
> 
> >>>>> Eli Zaretskii <eliz@gnu.org> writes:
> > Please explain the issue in more detail and in terms that someone who
> > doesn't use AUCTeX and has only superficial understanding of align.el
> > can understand and reason about.
> 
> > Three questions that pop up immediately, perhaps because I'm missing
> > something:
> 
> >   . why not use derived-mode-p instead of 'equal' in the run-if form
> 
> That's what I thought. Arash and I are proposing to _remove_ the run-if
> form so that `derived-mode-p' in `align-region' would do the expected
> job.
> 
> >     (and why remove it in the first place)?
> 
> See above.
> 
> >   . what is the rationale for not using align-tex-modes here, only
> >     latex-mode?
> 
> Because the current `tex-tabbing-separator' entry in `align-rules-list'
> excludes other modes by `run-if' form. I'm just following that behavior
> for AUCTeX modes. As I said in my previous message, this isn't much
> relavant; using `align-tex-modes' instead of '(latex-mode) would almost
> be the same for practical usage, provided that the `run-if' form is
> removed.
> 
> >   . why not just add the new LaTeX-mode to the list in
> >     align-tex-modes, so that people who use an old AUCTeX will not
> >     have their align rules broken?
> 
> That isn't necessary. Only `latex-mode' is needed there because
> `derived-mode-p' considers that `latex-mode' is parent of `LaTeX-mode'.
> However, the current `run-if' form excludes `LaTeX-mode' because if uses
> `eq', not `derived-mode-p'.

Then I'm okay with installing the proposed change.