Re: [PATCH 1/1] git-compat-util: add a test balloon for C99 support

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Nov 22, 2021, 11:44 UTC
Message-ID: <nycvar.QRO.7.76.6.2111221242320.63@tvgsbejvaqbjf.bet>
In-Reply-To: <xmqqk0h7423v.fsf@gitster.g>

Hi Junio & brian,

On Wed, 17 Nov 2021, Junio C Hamano wrote:

Show 29 quoted lines

> Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:
>
> >> Even MSVC, long a holdout against modern C, now supports both C11 and
> >> C17 with an appropriate update.  Moreover, even if people are using an
> >> older version of MSVC on these systems, they will generally need some
> >> implementation of the standard Unix utilities for the testsuite, and GNU
> >> coreutils, the most common option, has required C99 since 2009.
> >> Therefore, we can safely assume that a suitable version of GCC or clang
> >> is available to users even if their version of MSVC is not sufficiently
> >> capable.
> >
> > I am all in favor of this patch!
>
> I like the direction, but ...
>
> >> diff --git a/Makefile b/Makefile
> >> index 12be39ac49..22d9e67542 100644
> >> --- a/Makefile
> >> +++ b/Makefile
> >> @@ -1204,7 +1204,7 @@ endif
> >>  # Set CFLAGS, LDFLAGS and other *FLAGS variables. These might be
> >>  # tweaked by config.* below as well as the command-line, both of
> >>  # which'll override these defaults.
> >> -CFLAGS = -g -O2 -Wall
> >> +CFLAGS = -g -O2 -Wall -std=gnu99
>
> ... as has been already pointed out, this part probably should not
> be there.  It is not our intention to require gcc/clang, or to
> constrain newer systems to gnu99.

Another data point in favor of dropping this: our FreeBSD CI build reports a compile error with this:

	[...]
	archive.c:337:35: error: '_Generic' is a C11 extension
	[-Werror,-Wc11-extensions]
			strbuf_addstr(&path_in_archive, basename(path));
							^
	/usr/include/libgen.h:61:21: note: expanded from macro 'basename'
	#define basename(x)     __generic(x, const char *, __old_basename, basename)(x)
				^
	/usr/include/sys/cdefs.h:329:2: note: expanded from macro '__generic'
		_Generic(expr, t: yes, default: no)
		^
	1 error generated.

I verified in https://github.com/gitgitgadget/git/pull/1082 that this patch is indeed the cause of this compile error.

Ciao, Dscho