bug#60691: 29.0.60; Slow tree-sitter font-lock in ruby-ts-mode

[Yuan Fu]

> On Jan 12, 2023, at 11:57 PM, Eli Zaretskii <eliz@gnu.org> wrote:
> 
>> Cc: 60691@debbugs.gnu.org, juri@linkov.net
>> Date: Fri, 13 Jan 2023 01:40:56 +0200
>> From: Dmitry Gutov <dgutov@yandex.ru>
>> 
>> Managed to reproduce this after running the test in a couple of 
>> different files.
>> 
>> But 'M-x memory-usage' says no such command, and 'M-x memory-report' 
>> ends up with this error:
>> 
>> Debugger entered--Lisp error: (wrong-type-argument number-or-marker-p nil)
>>   memory-report--gc-elem(nil strings)
>>   memory-report--garbage-collect()
>>   memory-report()
> 
> This means GC is disabled in this session at the time you invoke
> memory-report.  Which shouldn't happen, of course.  It sounds like
> your pure Lisp storage overflowed, and that disabled GC.
> 
> And I think I see the problem: we use build_pure_c_string in treesit.c
> in places that we shouldn't.
> 
> Yuan, build_pure_c_string should only be used in places such as
> syms_of_treesit, which are called just once, during dumping.  Look at
> all the other calls to this function in the sources, and you will see
> it.  In all other cases, you should do one of the following:
> 
>  . for strings whose text is fixed, define a variable, give it the
>    value in syms_of_treesit using build_pure_c_string, then use that
>    variable elsewhere in the source

Can I define a bunch of static C variables and initialize them in 
syms_of_treesit, or they have to be all Lisp variables? Eg,

static Lisp_Object TREESIT_STAR;

...

void
syms_of_treesit (void)
{
...
TREESIT_STAR = build_pure_c_string ("*");
...
}

Yuan