Subject: Re: bug#58558: 29.0.50; re-search-forward is slow in some buffers

From: Stephen Berman <[email-masked]>
Date: Wed, 12 Apr 2023 16:38:53 +0200

On Wed, 12 Apr 2023 17:30:36 +0300 Eli Zaretskii <[email-masked]> wrote:

>> From: Stefan Monnier <[email-masked]>
>> Cc:  Ihor Radchenko <[email-masked]>, Eli Zaretskii <[email-masked]>,
>>   [email-masked],  [email-masked]
>> Date: Wed, 12 Apr 2023 10:06:03 -0400
>> 
>> > 1. emacs -Q
>> > 2. M-: (require 'cc-langs) <RET>
>> > 3. C-x b asd <RET>
>> > 4. M-: parse-sexp-lookup-properties <RET> => t
>> >
>> > On Emacs 28, (4) yields nil.
>> 
>> I suspect that the patch below might fix the immediate problem.
>> Of course, setting `parse-sexp-lookup-properties` should not have such
>> a major performance impact, so maybe we should keep digging into
>> the problem.
>
> Also, that code was there in Emacs 28 as well, so how come it suddenly
> has this effect now?

Note that, with emacs-28 -Q, `C-h v parse-sexp-lookup-properties' ==>

  parse-sexp-lookup-properties is a variable defined in ‘C source code’.
  
  Its value is nil

while with emacs-29 -Q, `C-h v parse-sexp-lookup-properties' ==>

  parse-sexp-lookup-properties is a variable defined in ‘C source code’.
  
  Its value is t
  Local in buffer *scratch*; global value is nil

Steve Berman