Re: [PATCH 21/25] pickaxe: use PCREv2 for -G and -S

Ævar Arnfjörð Bjarmason  [off-list ref] writes:

Follow-up b65abcafc7a (grep: use PCRE v2 for optimized fixed-string
search, 2019-07-01) and remove the use of kwset in the pickaxe code
for fixed-string search, in favor of optimistically using PCRE v2.

This does mean that the semantics of the -G option subtly change,
before it's an ERE, whereas now it'll be a PCRE if we're compiled with
PCRE. Since PCRE is almost entirely a strict superset of ERE syntax I
think this is OK.

Since Git is no longer a tool shared among 100 developers who are at
least acquaintances, there will be people who are bothered by the
differences, and such a change deserves a backward-compatibility
warning in the release notes, at least.

Recently, I discovered that I've been building my personal copy of
Git without LIBPCRE support at all for a long time.  It is possible
I've never built with LIBPCRE.  This series may give me incentive to
start using "git grep -P" ;-)

Thanks.