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

On Thu, Oct 06, 2016 at 03:25:00PM -0400, Rich Felker wrote:

quoted

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).

If you have autoconf testing for REG_STARTEND at configure time then
compat/regex.c can #include "config.h" and test for HAVE_REG_STARTEND
rather than for REG_STARTEND, or something like that.

Right, that part is easy; we do not even have to touch compat/regex.c,
because we already have such a knob in the Makefile (NO_REGEX), and
autoconf just needs to tweak that knob.

My question was whether we could do it without running a separate
compile (via autoconf or via the Makefile), and I think the answer is
"no".

-Peff