Subject: Re: [PATCH] regex: not all macOS platforms seem to have REG_ENHANCED

From: Junio C Hamano <[email-masked]>
Date: Fri, 20 Mar 2026 09:50:28 -0700

Johannes Schindelin <[email-masked]> writes:

> While this lets the build pass, it _does_ change behavior. Where
> previously, EREs were enforced, now BREs are silently enforced.

Enhanced is not about ERE/BRE but yes, you're right.  A build that
does not support REG_ENHANCED (due to the lack of definition in the
header) would compile but without enhanced features like \b, so the
"patch" above would not something I want to apply and blamed by
macOS users for X-<.

> So it might be desirable to instead imitate what `meson.build` does,
> namely define `USE_ENHANCED_BASIC_REGULAR_EXPRESSIONS` on macOS when
> compiling with `clang`.
>
> But that should already be the case:
> https://gitlab.com/git-scm/git/-/blob/v2.53.0/config.mak.uname#L151
>
>> ifeq ($(uname_S),Darwin)
>> [...]
>> 	USE_ENHANCED_BASIC_REGULAR_EXPRESSIONS = YesPlease
>
> So: hmm.

Hmm, indeed.