bug#59693: 29.0.50; treesitter in base buffer doesn't respond to modifications in indirect buffer correctly

[Yuan Fu]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Yuan Fu <casouri@gmail.com>
>> Date: Wed, 7 Dec 2022 15:13:19 -0800
>> Cc: Stefan Monnier <monnier@iro.umontreal.ca>,
>>  59693@debbugs.gnu.org,
>>  miha@kamnitnik.top
>> 
>> >> 1. Only allow base buffer to have parsers, no change is needed
>> >> for insdel.c, treesit_record_change can find the base buffer and
>> >> update its parsers. We can ask indirect buffers to use their base
>> >> buffer’s parser. Unless the base buffer is narrowed, I think it
>> >> will work fine.
>> > 
>> > I think this is fine, but we need to document it.
>> > 
>> >> I remember that there were a discussion along the lines of user-narrow vs 
>> >> low-level narrow, what was the outcome of that discussion?
>> > 
>> > Nothing in particular, and I don't think it's relevant.  If some mode needs
>> > to widen, it can.
>> > 
>> > Thanks.
>> 
>> Here is a patch that does #1.
>
> Thanks, a few minor comments for documentation below.
>
>> +If @var{buffer} (or the current buffer) is an indirect buffer, its
>> +base buffer is used instead.  That is, indirect buffers uses their
>                                           ^^^^^^^^^^^^^^^^^^^^^
> "use", in plural.
>
>> @@ -447,7 +455,9 @@ Using Parser
>>  @defun treesit-parser-list &optional buffer
>>  This function returns the parser list of @var{buffer}.  If
>>  @var{buffer} is @code{nil} or omitted, it defaults to the current
>> -buffer.
>> +buffer.  If @var{buffer} (or the current buffer) is an indirect
>             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> I'd say more concisely
>
>   If that buffer is an indirect buffer, ...
>
> And please add a cross-reference to the node where indirect buffers
> are described.
>
>> +buffer, its base buffer is used instead.  That is, indirect buffers
>> +uses their base buffer's parsers.
>    ^^^^
> "use".
>
>> +   Parsers in indirect buffers: We make indirect buffers to share the
>> +   parser of its base buffer.  See bug#59693 for reasoning.  */
>
> I'd rather have a short summary of the reasoning here than ask the
> readers to go to the bug tracker and read a long discussion.  Just
> explain why indirect buffers present a problem for a parser, and then
> say that we decided to do this as the easiest, simplest solution.
>
>> +If BUFFER (or the current buffer) is an indirect buffer, its base
>> +buffer is used instead.  That is, indirect buffers uses their base
>                                                       ^^^^
> "use"
>
>> +buffer's parsers.  If the base buffer is narrowed, an indirect buffer
>> +might not be able to retrieve information of the portion of the buffer
>> +text that are invisible in the base buffer.  Lisp programs should
>> +widen as necessary should they want to use a parser in an indirect
>> +buffer.  */)
>
> Here I would remove the second sentence: it is appropriate for the
> manual, but is redundant in the doc string, since the next sentence
> says it all.
>
>> @@ -1329,7 +1345,10 @@ DEFUN ("treesit-parser-list",
>>         Ftreesit_parser_list, Streesit_parser_list,
>>         0, 1, 0,
>>         doc: /* Return BUFFER's parser list.
>> -BUFFER defaults to the current buffer.  */)
>> +
>> +BUFFER defaults to the current buffer.  If BUFFER (or the current
>> +buffer) is an indirect buffer, its base buffer is used instead.  That
>> +is, indirect buffers uses their base buffer's parsers.  */)
>                         ^^^^
> "use"
>
> Otherwise, LGTM.

Cool, I fixed those and pushed.

Yuan