bug#63840: 29.0.91; c-ts-mode fails to fontify common C extension

[Eli Zaretskii]

> From: Yuan Fu <casouri@gmail.com>
> Date: Mon, 26 Jun 2023 22:54:16 -0700
> Cc: Theodor Thornhill <theo@thornhill.no>,
>  Po Lu <luangruo@yahoo.com>,
>  63840@debbugs.gnu.org
> 
> 
> 
> > On Jun 19, 2023, at 9:23 AM, Eli Zaretskii <eliz@gnu.org> wrote:
> > 
> >> From: Yuan Fu <casouri@gmail.com>
> >> Date: Sun, 18 Jun 2023 23:43:51 -0700
> >> Cc: Theodor Thornhill <theo@thornhill.no>,
> >> Po Lu <luangruo@yahoo.com>,
> >> 63840@debbugs.gnu.org
> >> 
> >>> On Jun 15, 2023, at 11:31 PM, Eli Zaretskii <eliz@gnu.org> wrote:
> >>> 
> >>>> From: Yuan Fu <casouri@gmail.com>
> >>>> Date: Thu, 15 Jun 2023 22:05:33 -0700
> >>>> Cc: Theodor Thornhill <theo@thornhill.no>,
> >>>> Po Lu <luangruo@yahoo.com>,
> >>>> 63840@debbugs.gnu.org
> >>>> 
> >>>>> Ping!  Any progress with this?
> >>>> 
> >>>> The best option is to ask tree-sitter-c to recognize $. I see a PR for 
> >>>> it but the author closed it shortly after posting, not sure what was 
> >>>> going on[1].
> >>> 
> >>> Any hope of re-opening it, or at least asking why it was closed
> >>> without fixing?
> >> 
> >> I asked on GitHub.
> >> 
> >>> 
> >>>> Fixing it ourselves involves checking every identifier during 
> >>>> fontification. Is that something we want to do?
> >>> 
> >>> How would that work?  Can you describe how could this be implemented?
> >>> It is hard to decide whether it's something we want to do without
> >>> knowing the implications.
> >> 
> >> I was going to write a demo implementation, but that actually would change 
> >> quite some lines. So let me just describe it for now. In 
> >> c-ts-mode--font-lock-settings, I would replace all the different types of 
> >> faces used for all the identifiers to a function. (If you search for 
> >> identifier in c-ts-mode--font-lock-settings, there are quite a few of 
> >> them.) This function would obviously receive the beg and end of the 
> >> identifier tree-sitter detects, and it would check if there are $ right 
> >> before or after the given range, if there is, it would extend the range 
> >> fontified.
> >> 
> >> For example, for a code like abc$de, tree-sitter might consider abc as an 
> >> identifier, and $ de to be error. The function I mentioned would look at 
> >> abc’s beg and end, and see that c is immediately followed by a $, so it 
> >> would extend the fontification range to include abc$de.
> > 
> > Thanks.  This sounds like a lot of hair, so let's first see how the
> > developers of the tree-sitter-c grammar respond.
> 
> Cool. (Not surprisingly) I didn’t get any reply on GitHub as for now. It 
> would be nice if tree-sitter-c (and other grammars) can have a separate 
> maintainer other than tree-sitter’s author. He seems to be heavily overloaded 
> right now (tree-sitter, a dozen grammars, Zed editor).

Would it be possible for you or someone else of the interested Emacs
users to submit a patch for the grammar library to support $, either
as an option or as an extension?  IOW, is it hard to modify the
TS grammar definitions for such relatively simple and straightforward
extensions?