bug#62333: 30.0.50; Issue with tree-sitter syntax tree during certain changes

[Yuan Fu]

> On Mar 25, 2023, at 9:28 PM, Eli Zaretskii <eliz@gnu.org> wrote:
> 
>> From: Yuan Fu <casouri@gmail.com>
>> Date: Sat, 25 Mar 2023 12:31:58 -0700
>> Cc: Dmitry Gutov <dgutov@yandex.ru>,
>> Wilhelm Kirschbaum <wkirschbaum@gmail.com>,
>> 62333@debbugs.gnu.org
>> 
>> 
>> I don’t think we should blindly widen in tree-sitter sexp functions, but not 
>> because of mmm-mode—tree-sitter ranges should have that mostly covered. My 
>> primary concern is that what if narrowing is intended by the caller?
> 
> What could be the reason for the caller to narrow when calling a
> sexp-movement function?  Keep in mind that the only narrowing that
> matters is one that prevents the sexp-movement function to find the
> target of the movement.

Maybe the user narrowed to a defun when writing code. There is a bug report on 
narrow-to-defun not working right in c-ts-mode, so there are definitely people 
who work like that.

>> But I don’t have any good idea for blink-matching right now.
> 
> We could leave this alone for now, but in that case let's at least add
> some FIXME comment in the relevant place(s), so that we could later
> revisit this.

Dmitry’s idea sounds good, we can add a tree-sitter backend for 
show-paren-data-function, and make the backend for blink-matching-paren 
configurable, then add a backend for it that uses show-paren-data-function, 
which in turn uses tree-sitter (or we add a backend that uses tree-sitter 
directly). In either case, the tree-sitter backend don’t need to use narrowing 
and we are good.

Yuan