Re: grep: fix multibyte regex handling under macOS (1819ad327b7a1f19540a819813b70a0e8a7f798f)

From: Jeff King <peff@peff.net>
Date: Feb 7, 2023, 18:23 UTC
Message-ID: <Y+KXC5b0qUg2/nxt@coredump.intra.peff.net>
In-Reply-To: <CALnO6CC2w5LUAjXVw7CWKAVobjFMc7M7jm7HuuGT1SO0q5cYbA@mail.gmail.com>

On Sun, Feb 05, 2023 at 02:51:05PM -0500, D. Ben Knoble wrote:

> Any thoughts on some sort of stop-gap measure to fix --word-diff while
> Git decides how to handle the regex engine incompatibilities? How
> important is the sequence of bytes at the end of --word-diff regexes
> in userdiff.c?

It comes from 664d44ee7f (userdiff: simplify word-diff safeguard, 2011-01-11). So presumably we'd want to figure out a way to accomplish the same thing in a portable way. I'm not sure that's possible, though, without making assumptions about the regex engine.

There's a little more discussion in the original thread:

  https://lore.kernel.org/git/561247.22837.qm@web110707.mail.gq1.yahoo.com/

but I didn't read it very carefully.

It may also be possible to play tricks with LC_CTYPE (either not setting it, or resetting before/after a regex), but that feels pretty hacky.

-Peff