bug#71681: 29.3.50; tree-sitter crash

[Yuan Fu]

> On Jun 24, 2024, at 12:46 AM, Yuan Fu <casouri@gmail.com> wrote:
> 
> 
> 
>> On Jun 23, 2024, at 10:38 AM, Juri Linkov <juri@linkov.net> wrote:
>> 
>>>> Evaluating this expression causes a crash:
>>>> 
>>>> (progn
>>>> (find-file (expand-file-name "src/treesit.c" installation-directory))
>>>> (c-ts-mode)
>>>> (font-lock-ensure 63209 63387))
>>>> 
>>>> in latest master, but not in latest emacs-29 (only in 5-months old 
>>>> emacs-29).
>>>> 
>>>> If this is not reproducible, I could provide more details.
>>>> 
>>>> libtree-sitter is at the latest version.
>>> 
>>> Hmm, I can’t reproduce with latest master and libtree-sitter. Maybe you can 
>>> send me the exact commits that you used?
>>> 
>>> Here’s mine:
>>> 
>>> Emacs: 72f2b01e318
>>> Tree-sitter: 6ec478c1
>> 
>> Probably reproducibility depends on the content of the src/treesit.c file.
>> Then the most reliable way to reproduce it is this:
>> 
>> 0. emacs -Q
>> 1. eval: (add-to-list 'major-mode-remap-alist '(c-mode . c-ts-mode))
>> 2. C-x v L
>> 3. in the *vc-change-log* buffer move point to the commit 20af58d3a13
>> 4. type D
>> 5. crash caused by diff-font-lock-syntax fontification that uses treesit
>> 
>> The numbers in (font-lock-ensure 63209 63387) above were extracted
>> from diff hunk boundaries that might be different when the file was edited.
> 
> I reproduce it once with the first set of commits you provided, but for some 
> reason couldn’t reproduce it again. I’m sure it’s something wrong that I did. 
> I’ll report back when I make progress. TBH it seems like something wrong with 
> tree-sitter itself, but I’ll make sure to figure out what’s the problem 
> exactly.
> 
> Yuan

Ok, I can reproduce it now. Looking into it…

Yuan