Re: [PATCH 1/3] compat: add qsort_s()

From: Junio C Hamano <gitster@pobox.com>
Date: Dec 1, 2016, 20:14 UTC
Message-ID: <xmqq7f7j9zkd.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <20161201193556.j2odwy3sepaxxq5a@sigill.intra.peff.net>

Jeff King <peff@peff.net> writes:

Show 7 quoted lines

> To make matters more fun, apparently[1] there are multiple variants of
> qsort_r with different argument orders. _And_ apparently Microsoft
> defines qsort_s, but it's not quite the same thing. But all of that can
> be dealt with by having more specific flags (HAVE_GNU_QSORT_R, etc).
>
> It just seems like we should be able to do a better job of using the
> system qsort in many cases.

If we were to go that route, perhaps we shouldn't have HAVE_QSORT_S so that Microsoft folks won't define it by mistake (instead perhaps call it HAVE_ISO_QSORT_S or something).

I like your suggestion in general. The body of git_qsort_s() on systems without ISO_QSORT_S can do

 - GNU qsort_r() without any change in the parameters,

 - Microsoft qsort_s() with parameter reordered, or

 - Apple/BSD qsort_r() with parameter reordered.

and that would cover the major platforms.

Eh, wait. BSD and Microsoft have paramters reordered in the callback comparison function. I suspect that would not fly very well.