bug#59415: 29.0.50; [feature/tree-sitter] c-ts-mode fails to fontify a portion of a large C file

[Yuan Fu <casouri@gmail.com>]

> On Nov 21, 2022, at 7:15 AM, Eli Zaretskii <eliz@gnu.org> wrote:
> 
>> From: Yuan Fu <casouri@gmail.com>
>> Date: Sun, 20 Nov 2022 17:27:16 -0800
>> Cc: Eli Zaretskii <eliz@gnu.org>,
>> 59415@debbugs.gnu.org
>> 
>> I pushed a change that uses treesit-node-on. Now scrolling in most parts of the buffer is pretty fast. Scrolling around 194770 is still laggy, because the node we get from treesit-node-on is still too large. I tried some heuristics but they didn’t work very well, IMO because tree-sitter couldn’t parse that part of the code very well. The code should observe a structure like {{}, {}, {}, {}, {}, …} where there are tens thousands of inner brackets, so ideally we only need to grab the {}’s in the region we want to fontify. But tree-sitter seems to understand it in some weird structure and we still end up with very large nodes, which is far larger than the region we want to fontify and is slow to query.
>> 
>> I’ll try to improve it further in the future, but for now I think it’s good enough (because in most cases fontification is pretty fast).
> 
> Agreed.
> 
> Thanks, I think we can close the bug now.
> 
> What do you think about enlarging treesit-max-buffer-size as I proposed
> up-thread?

Yeah we should do it, but to what value though? 40MB?

Yuan