Subject: Re: [v2.35.0 regression] some PCRE hangs under UTF-8 locale

From: Junio C Hamano <[email-masked]>
Date: Thu, 17 Feb 2022 14:56:50 -0800

René Scharfe <[email-masked]> writes:

> Subject: [PATCH] grep: fix triggering PCRE2_NO_START_OPTIMIZE workaround
>
> PCRE2 bug 2642 was fixed in version 10.36.  Our 95ca1f987e (grep/pcre2:
> better support invalid UTF-8 haystacks, 2021-01-24) worked around it on
> older versions by setting the flag PCRE2_NO_START_OPTIMIZE.  797c359978
> (grep/pcre2: use compile-time PCREv2 version test, 2021-02-18) switched
> it around to set the flag on 10.36 and higher instead, while it claimed
> to use "the same test done at compile-time".
>
> Switch the condition back to apply the workaround on PCRE2 versions
> _before_ 10.36.
>
> Signed-off-by: René Scharfe <[email-masked]>
> ---
>  grep.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/grep.c b/grep.c
> index 5bec7fd793..ef34d764f9 100644
> --- a/grep.c
> +++ b/grep.c
> @@ -386,7 +386,7 @@ static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt
>  	if (!opt->ignore_locale && is_utf8_locale() && !literal)
>  		options |= (PCRE2_UTF | PCRE2_MATCH_INVALID_UTF);
>
> -#ifdef GIT_PCRE2_VERSION_10_36_OR_HIGHER
> +#ifndef GIT_PCRE2_VERSION_10_36_OR_HIGHER
>  	/* Work around https://bugs.exim.org/show_bug.cgi?id=2642 fixed in 10.36 */

Oh, that's embarrassing.  The #ifdef and the comment sit next to
each other and they make contradicting statement.

>  	if (PCRE2_MATCH_INVALID_UTF && options & (PCRE2_UTF | PCRE2_CASELESS))
>  		options |= PCRE2_NO_START_OPTIMIZE;
> --
> 2.35.1