Re: Regression: git no longer works with musl libc's regex impl

From: Jeff King <peff@peff.net>
Date: Oct 6, 2016, 19:23 UTC
Message-ID: <20161006192339.3yddgxxk7jn7zfqx@sigill.intra.peff.net>
In-Reply-To: <CACBZZX4XPqZauD_M_ieOwVauT1fi3MQb4+6taELQaRG9M-Kz_w@mail.gmail.com>

On Thu, Oct 06, 2016 at 09:18:29PM +0200, Ævar Arnfjörð Bjarmason wrote:

Show 14 quoted lines

> On Tue, Oct 4, 2016 at 6:08 PM, Johannes Schindelin
> <Johannes.Schindelin@gmx.de> wrote:
> > As to making NO_REGEX conditional on REG_STARTEND: you are talking about
> > apples and oranges here. NO_REGEX is a Makefile flag, while REG_STARTEND
> > is a C preprocessor macro.
> >
> > Unless you can convince the rest of the Git developers (you would not
> > convince me) to simulate autoconf by compiling an executable every time
> > `make` is run, to determine whether REG_STARTEND is defined, this is a
> > no-go.
> 
> But just to clarify, does anyone have any objection to making our
> configure.ac compile a C program to check for this sort of thing?
> Because that seems like the easiest solution to this class of problem.

No, I think that is the exact purpose of configure.ac and autoconf.

It would be neat if we could auto-fallback during the build. Rich suggested always compiling compat/regex.c, and just having it be a noop at the preprocessor level. I'm not sure if that would work, though, because we'd have to include the system "regex.h" to know if we have REG_STARTEND, at which point it is potentially too late to compile our own regex routines (we're potentially going to conflict with the system declarations).

-Peff