GNU bug report logs - #65726
29.1.50; Crash in regexp engine

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Package: emacs;

Reported by: martin rudalics <rudalics <at> gmx.at>

Date: Mon, 4 Sep 2023 07:48:02 UTC

Severity: normal

Found in version 29.1.50

Fixed in version 30.1

Done: Stefan Kangas <stefankangas <at> gmail.com>

Bug is archived. No further changes may be made.

Full log

Message #112 received at 65726 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Mattias Engdegård <mattias.engdegard <at> gmail.com>
Cc: martin rudalics <rudalics <at> gmx.at>, Eli Zaretskii <eliz <at> gnu.org>,
 65726 <at> debbugs.gnu.org
Subject: Re: bug#65726: 29.1.50; Crash in regexp engine
Date: Sun, 17 Sep 2023 23:59:32 -0400

> So maybe we should `skip_noops` before looking at the destinations to
> decide if it's a loop?

Nah, just introduces other problems :-(

BTW maybe we should replace

    31:     /on_failure_jump_loop to 37
    34:     /jump to 9

with

    31:     /on_failure_dont_jump_loop to 9

It's quite funny actually: with the current bytecodes, every iteration
of a backtracking greedy loop runs `jump + on_failure_jump`, whereas for
a non-greedy loop every iteration runs just a single `on_failure_jump`.
Yet those bytecodes predate the introduction of non-greedy loops :-)

[ Of course, there are reasons for it, beside historical ones: it's harder
  to rewrite a loop that ends with `on_failure_dont_jump_smart` into one
  using `on_failure_keep_string_jump` :-(  ]


        Stefan
This bug report was last modified 1 year and 242 days ago.

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