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

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

On Fri, Feb 03 2023, Jeff King wrote:

> On Thu, Feb 02, 2023 at 05:22:37PM +0100, demerphq wrote:
>
>> I've been lurking watching some of the regex discussion on the list
>> and personally I think it is asking for trouble to use "whatever regex
>> engine is traditional in a given environment" instead of just choosing
>> a good open source engine and using it consistently everywhere.  I
>> don't really buy the arguments I have seen to justify a policy of "use
>> the standard library version"; regex engines vary widely in
>> performance and implementation and feature set, and even the really
>> good ones do not entirely agree on every semantic[1], so if you don't
>> standardize you will be forever dealing with bugs related to those
>> differences.
>
> I think this is a perennial question for portable software: is it better
> to be consistent across platforms (by shipping our own regex engine), or
> consistent with other programs on the same platform (by using the system
> regex).

*nod*

> I don't have a strong opinion either way. The main concern I'd have is
> handling dependencies. I like pcre a lot, but I'm not sure that I would
> want building Git to require pcre on every platform. If there's an
> engine we can ship as a vendored dependency that builds everywhere, that
> helps.

We can just make that fallback engine be PCRE. I submitted patches a
while ago to include a minimal version of it in compat/pcre, as we seem
to have some allergy to external dependencies:
https://lore.kernel.org/git/20170511175115.648-1-avarab@gmail.com/

It's ~80k lines instead of compat/regex's ~15k, but it's actually
maintained, and would be much easier to upgrade.