Eli Zaretskii <eliz@gnu.org> writes:

>> Date: Tue, 07 Feb 2023 23:20:09 +0100
>> From:  Daniel Martín via "Bug reports for GNU Emacs,
>>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
>> 
>> 
>> Steps to reproduce the problem:
>> 
>> emacs -Q
>> C-x C-f emacs/src/xdisp.c RET
>> M-x c-ts-mode RET
>> C-x h
>> TAB
>> 
>> Expected result:
>> 
>> The buffer is reindented.
>> 
>> Actual results:
>> 
>> The operation fails with this error:
>> 
>> Debugger entered--Lisp error: (wrong-type-argument integer-or-marker-p nil)
>>   treesit-indent-region(1 1214226)
>>   indent-region(1 1214226)
>>   indent-for-tab-command(nil)
>>   funcall-interactively(indent-for-tab-command nil)
>>   call-interactively(indent-for-tab-command nil nil)
>>   command-execute(indent-for-tab-command)
>
> Thank you for your report.
>
> Yuan and Theo, could you please look into this?  I briefly stepped
> through the code involved in the problem, and it sounds like it makes
> some assumptions regarding the nodes which are not necessarily true in
> Real Life.

c-ts-mode from the tip of the emacs-29 branch can indent xdisp.c without
failures if I apply the patch from bug#61691 and the patch attached to
this email message.

It is very slow, though, compared to c-mode.  I have a very fast machine
and it took around 10 minutes to indent the whole file, while c-mode
indented the file in 30-40 seconds.  I guess the algorithm in
treesit-indent-region doesn't scale very well for very big files like
xdisp.c.