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

[Dmitry Gutov <dgutov@yandex.ru>]

On 28/03/2023 14:32, Eli Zaretskii wrote:
>> Date: Tue, 28 Mar 2023 02:06:17 +0300
>> Cc: wkirschbaum@gmail.com, casouri@gmail.com, 62333@debbugs.gnu.org
>> From: Dmitry Gutov <dgutov@yandex.ru>
>>
>> On 27/03/2023 16:39, Eli Zaretskii wrote:
>>>> Date: Mon, 27 Mar 2023 08:24:42 +0000
>>>> From: Gregory Heytings<gregory@heytings.org>
>>>> cc: Eli Zaretskii<eliz@gnu.org>,wkirschbaum@gmail.com,casouri@gmail.com,
>>>>       62333@debbugs.gnu.org
>>>>
>>>>>> Which is a fragile, semi-broken means, as we all know.
>>>>> What is a broken mess, is user-level narrowing. And how the downstream
>>>>> code can never guess the purpose the narrowing was applied for.
>>>> Note that this is what labeled narrowings attempts to solve.
>>> Labeled narrowing cannot solve this because it does nothing to
>>> alleviate the problems with user-defined narrowing.  So if the user
>>> narrows the buffer, we cannot do anything to safely widen in the
>>> general case, and labeled narrowing cannot help us.
>>
>> Is that because we don't think the user level narrowing is done purely
>> for visual effect?
> 
> Indeed, it isn't always for visual effect.

When isn't it? Is there a way to determine that from code?

>> judging by regular user requests for make this or that command
>> ignore user-level narrowing, it seems like "purely visual" should be the
>> default interpretation.
> 
> I think you base your judgment on feedback from users who are not used
> to take advantage of narrowing in editing.  I think most young people
> aren't, since this feature is more-or-less unique to Emacs.

Either narrowing should be used to change lexical/grammatical/etc 
context, or it should not. Do we have any documentation that says one or 
the other way? That should affect how Lisp code deals with narrowing -- 
which interactive functions should widen, and so on.