GNU bug report logs - #64128
regexp parser zero-width assertion bugs

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Message #23 received at 64128 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Mattias Engdegård <mattias.engdegard <at> gmail.com>
Cc: Eli Zaretskii <eliz <at> gnu.org>, Paul Eggert <eggert <at> cs.ucla.edu>,
 64128 <at> debbugs.gnu.org
Subject: Re: bug#64128: regexp parser zero-width assertion bugs
Date: Sun, 18 Jun 2023 23:04:49 -0400

> To make everything clear, we have to groups of zero-width assertions:
>
> Group A: ^ $ \` \' \b \B

IIRC `^` is only special if it's at the beginning of a group, so `^*` will
always treat this * as a literal, right?
"Similarly" `$` is only special if it's at the end of a group, so `$*` will
always be a repetition of the $ character no?

So the remaining problematic elements are \` \' \b and \B

I suspect if we don't want to signal errors, the next best thing is to
treat them like group B.


        Stefan

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