Subject: Re: bug#55744: infinite loop

From: Lars Ingebrigtsen <[email-masked]>
Date: Wed, 01 Jun 2022 17:35:04 +0200

"Daniel R. Grayson" <[email-masked]> writes:

> Okay, I did that, and it seems to be this:
>
> (defconst M2-mode-font-lock-keywords
>           '("///\\(/?/?[^/]\\|\\(//\\)*////[^/]\\)*\\(//\\)*///" .
> 'font-lock-string-face) )

That's a regexp with a lot of backtracking, I think (i.e., elements that
can be matched both by the ?'s as well as the two *'s).  So matching
this will be slow, which results in the hangs you're seeing when Emacs
is trying to match that to the text in the buffer.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no