GNU bug report logs - #55744
infinite loop

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Message #28 received at 55744 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: "Daniel R. Grayson" <danielrichardgrayson <at> gmail.com>
Cc: 55744 <at> debbugs.gnu.org
Subject: Re: bug#55744: infinite loop
Date: Wed, 01 Jun 2022 17:35:04 +0200

"Daniel R. Grayson" <danielrichardgrayson <at> gmail.com> 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

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