Re: Tree sitter support for C-like languages

[Yuan Fu <casouri@gmail.com>]

> On Nov 15, 2022, at 10:38 AM, Eli Zaretskii <eliz@gnu.org> wrote:
> 
>> From: Yuan Fu <casouri@gmail.com>
>> Date: Tue, 15 Nov 2022 10:18:21 -0800
>> Cc: Stefan Monnier <monnier@iro.umontreal.ca>,
>> theo@thornhill.no,
>> emacs-devel@gnu.org
>> 
>>> Maybe we should grow some augmentations for tree-sitter, at least
>>> given enough time.  Or maybe it's possible to identify the parts where
>>> this happens by some tree-sitter indications, and tweak the faces in
>>> those regions in some way.
>> 
>> I don’t know how could you improve this in tree-sitter since macros are literally “define you own syntax”. We can reasonably fix the highlighting for some of our macros like DEFUN. As a demonstration I added some emacs-devel-specific rules (that are disabled by default). Run this:
>> 
>> (add-hook 'c-ts-mode-hook
>>          (lambda ()
>>            (treesit-font-lock-recompute-features '(emacs-devel))))
>> 
>> And restart c-ts-mode, and DEFUN’s should look normal now.
> 
> I will try that when I have time, thanks.  But if this indeed works
> well, why not do something similar to fix more warnings?  

Truth to be told, I don’t know how to fix errors around preprocessor directive (#ifdef’s). Our macros shouldn’t be hard to fix. We can fix them as we encounter them.

> And why not
> make this the default, instead of asking users to write mode hooks?

Because this is Emacs-specific? It specifically fixes highlight for the DEFUN macro, nothing else. We can add some dir-local config that automatically enables this.

Yuan