bug#55744: infinite loop

[Lars Ingebrigtsen]

"Daniel R. Grayson" <danielrichardgrayson@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.

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