From owner-freebsd-hackers@FreeBSD.ORG  Tue Jul  5 10:11:37 2011
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Date: Tue, 05 Jul 2011 12:11:36 +0200
From: Dimitry Andric <dim@FreeBSD.org>
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To: Robert Millan <rmh@debian.org>
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Cc: freebsd-hackers@freebsd.org, Ed Maste <emaste@freebsd.org>
Subject: Re: [PATCH] __FreeBSD_cc_version in <sys/cdefs.h>
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On 2011-07-04 18:30, Robert Millan wrote:
> This patch fixes a (harmless) warning when<sys/cdefs.h>  is parsed by
> upstream version of GCC.
>
> -#if __FreeBSD_cc_version >= 300001 && defined(__GNUC__) && !defined(__INTEL_COMPILER)
> +#if defined(__FreeBSD_cc_version) && __FreeBSD_cc_version >= 300001 && defined(__GNUC__) && !defined(__INTEL_COMPILER)

As far as I can see, this code only gives warnings when compiled with
gcc 4.5 or higher, and when using the -Wundef flag.  Isn't it easier to
just remove the -Wundef flag here?

Additionally, it looks like the C standard is a bit vague about whether
the preprocessor uses short-circuited boolean evaluation (although gcc's
manual says it does), so I'm not sure whether this patch solves the
problem properly either.