bug#80837: treesit-forward-comment off-by-one issue: overshoots by one character

> From: Juri Linkov <[email protected]>
> Cc: Sean Whitton <[email protected]>,  [email protected],  Eli
>  Zaretskii <[email protected]>,  [email protected],  [email protected]
> Date: Wed, 19 Aug 2026 19:53:26 +0300
> 
> >>>> I'm very sorry to reopen it, but we still have the same problem
> >>>> in the emacs-31 release branch.  For example, try in c-ts-mode to
> >>>> uncomment a comment, and it leaves the trailing */ comment endings.
> >>> 
> >>> I'm not sure this is important enough to block the release, but we can
> >>> at least discuss whether we think there is a possible small,
> >>> non-invasive for the emacs-31 branch.  Yuan, sorry to go back and forth
> >>> so many times here, but do you think there is a way to do it less
> >>> invasively?
> >> 
> >> Leaving emacs-31 unfixed makes c-ts-mode somewhat unusable
> >> since uncommenting is a frequent operation.  If a small fix
> >> for treesit-forward-comment is still unfeasible, then at least
> >> we need to disable the 'comment' thing for c-ts-mode
> >> in the release branch:
> >> 
> >> diff --git a/lisp/progmodes/c-ts-mode.el b/lisp/progmodes/c-ts-mode.el
> >> index 5f064716a89..3efbee6f8a7 100644
> >> --- a/lisp/progmodes/c-ts-mode.el
> >> +++ b/lisp/progmodes/c-ts-mode.el
> >> @@ -1275,8 +1275,7 @@ c-ts-mode--thing-settings
> >>                     "goto_statement"
> >>                     "case_statement")))
> >>     (text ,(regexp-opt '("comment"
> >> -                         "raw_string_literal")))
> >> -    (comment "comment"))
> >> +                         "raw_string_literal"))))
> >>   "`treesit-thing-settings' for both C and C++.")
> >
> > Actually this makes a lot of sense. I don’t think we are missing anything
> > by not using tree-sitter for the comment thing, forward/backward-comment
> > already works perfectly fine without it. We can also add a comment to
> > explain why we leave the comment thing out for c-ts-mode in the release
> > version.
> 
> Eli and Sean, is this change ok to install on the release branch?

I don't mind, but please wait for Sean to respond.