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bug#59426: 29.0.50; [tree-sitter] Some functions exceed maximum recursio
From: |
Yuan Fu |
Subject: |
bug#59426: 29.0.50; [tree-sitter] Some functions exceed maximum recursion limit |
Date: |
Mon, 21 Nov 2022 08:52:53 -0800 |
> On Nov 21, 2022, at 5:19 AM, Eli Zaretskii <eliz@gnu.org> wrote:
>
>> From: Yuan Fu <casouri@gmail.com>
>> Date: Sun, 20 Nov 2022 16:53:45 -0800
>>
>>
>> Emacs crashed on a very large C file when c-ts-mode is on, because
>> the function building the imenu list tries to walk through the whole
>> parse tree, and end up recusing ~10k times because of how deep the parse
>> tree is. These recursive functions should have a built-in limit. Does
>> Emacs already have some way to determined the max recursion limit on
>> each system? Or should we come up with some hard-coded numbers?
>
> Is the recursion in our code, or is it in libtree-sitter?
In our code, when we walk the parse tree.
>
> If the former, one solution, albeit a crude one, is to track the recursion
> level and error out if it becomes too deep. Another solution is to handle
> the stack in our code, in which case the stack can be allocated on the heap.
That’s my idea, hence my asking for a reasonable way to get a limit. I think a
hard limit is totally reasonable, because there is no way for a “normal” parse
tree to be 10k levels deep (that means the source program is 10k levels deep,
ver unlikely for any program a human would write or a machine would generated).
The one I observed is likely due to the parser misunderstanding the source (due
to errors in the code). Plus, I don’t think any user would want to walk that
deep into the parse tree either. If someone expects to walk that deep into a
parse tree, her program is ill-designed.
The tree-walking function already has a limit parameter, we just need to give
it a default value.
> Yet another solution is to replace stack-based recursive algorithm with
> queue-based iteration, like if you replace depth-first search with
> breadth-first search.
Because of reasons above, I think a hard limit is good enough.
>
> I'm sure there are other ideas as well.
Yuan
- bug#59426: 29.0.50; [tree-sitter] Some functions exceed maximum recursion limit, (continued)
- bug#59426: 29.0.50; [tree-sitter] Some functions exceed maximum recursion limit, Mattias Engdegård, 2022/11/21
- bug#59426: 29.0.50; [tree-sitter] Some functions exceed maximum recursion limit, Yuan Fu, 2022/11/21
- bug#59426: 29.0.50; [tree-sitter] Some functions exceed maximum recursion limit, Eli Zaretskii, 2022/11/21
- bug#59426: 29.0.50; [tree-sitter] Some functions exceed maximum recursion limit, Stefan Kangas, 2022/11/21
- bug#59426: 29.0.50; [tree-sitter] Some functions exceed maximum recursion limit, Po Lu, 2022/11/21
- bug#59426: 29.0.50; [tree-sitter] Some functions exceed maximum recursion limit, Mattias Engdegård, 2022/11/22
bug#59426: 29.0.50; [tree-sitter] Some functions exceed maximum recursion limit, Eli Zaretskii, 2022/11/21
- bug#59426: 29.0.50; [tree-sitter] Some functions exceed maximum recursion limit,
Yuan Fu <=