Date: Tue, 16 Oct 2012 05:09:31 +1100 (EST) From: Bruce Evans <brde@optusnet.com.au> To: Jilles Tjoelker <jilles@stack.nl> Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, Gleb Smirnoff <glebius@FreeBSD.org>, src-committers@FreeBSD.org, John Baldwin <jhb@FreeBSD.org> Subject: Re: svn commit: r241546 - head/sys/contrib/ipfilter/netinet Message-ID: <20121016045904.Q15233@besplex.bde.org> In-Reply-To: <20121015151147.GA92923@stack.nl> References: <201210141503.q9EF37rE087018@svn.freebsd.org> <201210150834.09553.jhb@freebsd.org> <20121015143658.GU89655@FreeBSD.org> <20121015151147.GA92923@stack.nl>
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On Mon, 15 Oct 2012, Jilles Tjoelker wrote: > On Mon, Oct 15, 2012 at 06:36:58PM +0400, Gleb Smirnoff wrote: >> On Mon, Oct 15, 2012 at 08:34:09AM -0400, John Baldwin wrote: >> J> On Sunday, October 14, 2012 11:03:07 am Gleb Smirnoff wrote: >> J> > Author: glebius >> J> > Date: Sun Oct 14 15:03:06 2012 >> J> > New Revision: 241546 >> J> > URL: http://svn.freebsd.org/changeset/base/241546 > >> J> > Log: >> J> > Fix defines in r241245. We actually don't define FreeBSD. > >> J> > Reported & tested by: Oleg Ginzburg > >> J> Seems like it should be using 'defined(__FreeBSD_version)' instead? > >> AFAIU, the construction which left after r241546 works fine. Anything >> undefined resolves to zero, so in case of non-FreeBSD build we test >> if (0 > 10000019) and this fails which is what we expect. > >> I have used this construction several times already without any side >> effects. I have also seen it in some software in ports, where it works >> okay, too. > > The C standard indeed permits this, but gcc -Wundef will warn about it. > That compiler warning is in CWARNFLAGS in sys/conf/kern.mk so I suggest > adding the 'defined(__FreeBSD_version) &&'. The C standard requires this, but some misconfigured compilers like gcc -Wundef warn about it, and some non-C compilers like gcc -Wundef -Werror fail on it. The bug is sometimes hidden by -Wno-system-headers, but FreeBSD wants to detect bugs in system headers so it sets -Wsystem-headers at WARNS >= 1, and then the buggy compilers find this non-bug in system headers. The result is uglification of many system headers to use if `defined(__FOO) && ...' instead of depending on this standard and useful feature. Bruce
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