bug#59455: 29.0.50; Treesit font lock changes unrelated code

[Yuan Fu <casouri@gmail.com>]

Theodor Thornhill <theo@thornhill.no> writes:

> On 22 November 2022 11:05:50 CET, Yuan Fu <yuf011@ucsd.edu> wrote:
>>
>>Theodor Thornhill <theo@thornhill.no> writes:
>>
>>> Hi Yuan!
>>>
>>> I've noticed some strange behavior with font-lock lately in c-ts-mode,
>>> and also in all the other ts modes.
>>>
>>> to reproduce:
>>>
>>> emacs -Q
>>>
>>> C-x C-f foo.c RET
>>>
>>> Insert this:
>>>
>>> ```
>>> /* lol lol lol lol lol lol lol lol lol lol */
>>> /* lol lol lol lol lol lol lol lol lol lol */
>>> /* lol lol lol lol lol lol lol lol lol lol */
>>> /* lol lol lol lol lol lol lol lol lol lol */
>>> /* lol lol lol lol lol lol lol lol lol lol */
>>> /* lol lol lol lol lol lol lol lol lol lol */
>>> /* lol lol lol lol lol lol lol lol lol lol */
>>> /* lol lol lol lol lol lol lol lol lol lol */
>>> /* lol lol lol lol lol lol lol lol lol lol */
>>>
>>> int
>>> foo (void)
>>> {
>>>   return 5;
>>> }
>>>
>>> int
>>> foo (void)
>>> {
>>>   if (x)
>>>     {
>>>       return 5;
>>>     }
>>> }
>>>
>>> int
>>> foo (void)
>>> {
>>>   return 5;
>>> }
>>> ```
>>>
>>> M-x c-ts-mode RET
>>>
>>> Now on the first line, repeatedly press 'M-c' (capitalize-word) and
>>> watch the highlights of the rest of the file jump around.  Then try
>>> undoing the changes by repeatedly pressing 'C-/' until you are back at
>>> the state right after the first insert.  Now highlights are messed up.
>>>
>>> I'm not sure where to start looking for this, but I do remember there
>>> being some issues in Eglot with these "multi-edit" commands.
>>>
>>> If you have some pointers for where to look I can dig around :)
>>
>>Thanks for the catch! It is due to tree-sitter not correctly recording
>>changes in casefiddle.c. I’ve fixed it now. 
>
>
>> Now you can Lol as much as your heart desire.
>
> Don't you always capitalize lols at the top of your files? 

I should do it more, heard that it’s a good warm-up for programming :-)
Closing.

Yuan