From: "brian m. carlson" <sandals@crustytoothpaste.net>
To: Jeff King <peff@peff.net>
Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>,
Eric Sunshine <sunshine@sunshineco.com>
Subject: Re: [PATCH v2 1/1] git-compat-util: add a test balloon for C99 support
Date: Wed, 17 Nov 2021 01:44:23 +0000 [thread overview]
Message-ID: <YZRedzMSodOYjjPP@camp.crustytoothpaste.net> (raw)
In-Reply-To: <YZOh370ZMMqSADUE@coredump.intra.peff.net>
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On 2021-11-16 at 12:19:43, Jeff King wrote:
> On Tue, Nov 16, 2021 at 02:12:41AM +0000, brian m. carlson wrote:
>
> > The C99 standard was released in January 1999, now 22 years ago. It
> > provides a variety of useful features, including variadic arguments for
> > macros, declarations after statements, variable length arrays, and a
> > wide variety of other useful features, many of which we already use.
>
> I like the idea of being able to assume C99. And I know this list is
> just "here are some things we could do". But I'd like to express caution
> over variable length arrays. We've already had problems with alloca()
> causing stack exhaustion, and VLAs are basically the same thing. And the
> worst part is there's no way to recover; you just get a segfault.
Since it looks like I'll be doing a v3, I'll reroll without that.
> > diff --git a/Makefile b/Makefile
> > index 12be39ac49..893d533d22 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
> > LDFLAGS =
> > CC_LD_DYNPATH = -Wl,-rpath,
> > BASIC_CFLAGS = -I.
>
> Do most compilers understand -std=gnu99? It seems like we're breaking
> the out-of-the-box build for everything that isn't gcc or clang.
I'm pretty sure -Wall is GCC- and clang-specific, as is -Wl,-rpath, so I
think we've already crossed that bridge. There are places in
config.mak.uname where they're specifically overridden for that reason.
-std=gnu99 (or -std=c99) is absolutely required for sparse, though,
since it defaults to C89 (at least in CI).
> I understand that older versions of gcc (prior to 5.1.0, from my
> digging) default to gnu89, and so they would be broken _without_ this.
> So it is a tradeoff one way or the other. But somehow this seems
> backwards to me. We should assume that modern compilers support C99 out
> of the box, and put the burden on older ones to trigger C99 support in
> whatever non-portable way they need.
We'll have to adjust the CI job that builds with GCC 4.8, but I can do
that. I just am not eager to hear complaints from people that it
doesn't work out of the box, especially since CentOS 7 is going to hit
this case.
--
brian m. carlson (he/him or they/them)
Toronto, Ontario, CA
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next prev parent reply other threads:[~2021-11-17 1:44 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-14 21:24 [PATCH 0/1] Add a test balloon for C99 brian m. carlson
2021-11-14 21:24 ` [PATCH 1/1] git-compat-util: add a test balloon for C99 support brian m. carlson
2021-11-15 1:14 ` Ævar Arnfjörð Bjarmason
2021-11-15 1:54 ` brian m. carlson
2021-11-15 3:16 ` Eric Sunshine
2021-11-16 1:53 ` brian m. carlson
2021-11-22 11:47 ` Johannes Schindelin
2021-11-14 21:43 ` [PATCH 0/1] Add a test balloon for C99 brian m. carlson
2021-11-15 7:00 ` Junio C Hamano
2021-11-15 22:41 ` brian m. carlson
2021-11-16 19:02 ` Junio C Hamano
2021-11-17 1:51 ` brian m. carlson
2021-11-16 2:12 ` [PATCH v2 0/1] Add a test balloon for C99 support brian m. carlson
2021-11-16 2:12 ` [PATCH v2 1/1] git-compat-util: add " brian m. carlson
2021-11-16 12:19 ` Jeff King
2021-11-16 12:54 ` Ævar Arnfjörð Bjarmason
2021-11-16 14:54 ` Jeff King
2021-11-17 2:53 ` brian m. carlson
2021-11-17 3:01 ` Jeff King
2021-11-17 23:18 ` brian m. carlson
2021-11-17 23:45 ` Carlo Arenas
2021-11-18 2:26 ` Ævar Arnfjörð Bjarmason
2021-11-18 19:10 ` Junio C Hamano
2021-11-17 8:49 ` Junio C Hamano
2021-11-16 19:44 ` Phillip Wood
2021-11-17 1:44 ` brian m. carlson [this message]
2021-11-17 2:58 ` Jeff King
2021-11-30 20:43 ` Microsoft's C language policy (was: [PATCH 0/1] Add a test balloon for C99) Ævar Arnfjörð Bjarmason
2021-11-30 22:37 ` brian m. carlson
2021-12-01 1:40 ` [PATCH v3 0/1] Add a test balloon for C99 support brian m. carlson
2021-12-01 1:40 ` [PATCH v3 1/1] git-compat-util: add " brian m. carlson
2021-12-02 17:38 ` Johannes Schindelin
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