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

[Yuan Fu]

> 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).

Yuan