Subject: bug#61514: 30.0.50; sadistically long xml line hangs emacs

From: Gregory Heytings <[email-masked]>
Date: Mon, 20 Feb 2023 17:14:11 +0000

>
> where I can even reduce the regexp down to "[-._[:alnum:]]*\t*=".
>
> Looks like we're missing a case in our backtracking-elimination code.
>

Apparently we're doing the same thing at the same moment ;-)

I simplified it down to:

(with-current-buffer (get-buffer-create "*bug*")
   (erase-buffer)
   (insert (make-string 266666 ?n))
   (goto-char (point-min))
   (looking-at "[[:alpha:]]*=*"))

This fails with 266666, and succeeds with 266665.