bug#59662: 29.0.50; [PATCH] Add treesit--indent-defun

[Eli Zaretskii]

> From: Theodor Thornhill <theo@thornhill.no>
> Cc: casouri@gmail.com, 59662@debbugs.gnu.org, casouri@gmail.org
> Date: Thu, 08 Dec 2022 09:11:28 +0100
> 
> > Bonus points for adding something that could use treesit.el
> > capabilities, when those are available, instead of syntax-ppss, to
> > determine when we are in a comment or in a string.  Or maybe Theo or
> > Yuan could suggest such an addition.
> 
> This works perfectly as is in *-ts-modes.  At least for modes where
> syntax-table is set correctly.  I don't think there's a reason to enable
> treesit.el capabilities, unless there's a case where this doesn't work.

My point is that tree-sitter in many cases parses the program better
than syntax-ppss.  So if we can use its information about comments and
strings, why not do that?  It's exactly the same logic that Dmitry
used:

> +    (if (or (nth 8 (syntax-ppss))
> +            (re-search-forward comment-start-skip (line-end-position) t))

which falls back on regexp search if syntax-ppss cannot help.  I'm
asking why not try tree-sitter before we fall back on syntax-ppss or
regexp search?

Does that make sense?  If not, why not?

> If this ends up in master, should I backport some similar feature for
> the *ts-modes?

Why do we need this on the release branch?  A general
indent-or-fill-comment feature for all the progmodes didn't exist
until now, which is why we intend to install this on master.