GNU bug report logs - #59426
29.0.50; [tree-sitter] Some functions exceed maximum recursion limit

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Message #62 received at 59426 <at> debbugs.gnu.org (full text, mbox):

From: Yuan Fu <casouri <at> gmail.com>
To: Mattias Engdegård <mattiase <at> acm.org>
Cc: luangruo <at> yahoo.com, 59426 <at> debbugs.gnu.org, Eli Zaretskii <eliz <at> gnu.org>,
 stefankangas <at> gmail.com
Subject: Re: bug#59426: 29.0.50; [tree-sitter] Some functions exceed maximum
 recursion limit
Date: Mon, 21 Nov 2022 11:00:56 -0800

> On Nov 21, 2022, at 10:20 AM, Mattias Engdegård <mattiase <at> acm.org> wrote:
> 
>> And don't forget that GC is also highly recursive and eats up a lot of stack space.
> 
> Not any more.
> 
> ---
> 
> If tree-sitter really needs a deep stack whose size depend on the input file and grammar in an unbounded way, then it shouldn't use the C stack; that would be an unnecessary restriction on the files that could be edited. A dynamically allocated stack could still have a limit, but it would be decoupled from the C stack size.

Fortunately tree-sitter doesn’t need a deep stack. I don’t think any human-written or even machine generated source file is ever intended to parse into a tree of more than 1k level. Eg, who would write/generate a function that has thousands level of nested brackets {{{{{{{{{{{{{{{{…. ? (Unless they want to try to break the parser/compiler.) So a sane limit is more than enough, just to guard against weird source files that makes the parser (erroneously) generate very very tall trees.

Yuan

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