Date: Mon, 15 Oct 2012 16:26:50 -0700 From: Garrett Cooper <yanegomi@gmail.com> To: Gleb Smirnoff <glebius@freebsd.org> Cc: src-committers@freebsd.org, John Baldwin <jhb@freebsd.org>, Jilles Tjoelker <jilles@stack.nl>, svn-src-all@freebsd.org, Bruce Evans <brde@optusnet.com.au>, svn-src-head@freebsd.org Subject: Re: svn commit: r241546 - head/sys/contrib/ipfilter/netinet Message-ID: <CAGH67wSGetFXNnUTGHRTz1r5pLDTMaCRCTLWOU3thq1fWw0Yeg@mail.gmail.com> In-Reply-To: <20121015222333.GY89655@FreeBSD.org> References: <201210141503.q9EF37rE087018@svn.freebsd.org> <201210150834.09553.jhb@freebsd.org> <20121015143658.GU89655@FreeBSD.org> <20121015151147.GA92923@stack.nl> <20121016045904.Q15233@besplex.bde.org> <20121015222333.GY89655@FreeBSD.org>
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On Mon, Oct 15, 2012 at 3:23 PM, Gleb Smirnoff <glebius@freebsd.org> wrote: > On Tue, Oct 16, 2012 at 05:09:31AM +1100, Bruce Evans wrote: > B> > On Mon, Oct 15, 2012 at 06:36:58PM +0400, Gleb Smirnoff wrote: > B> >> On Mon, Oct 15, 2012 at 08:34:09AM -0400, John Baldwin wrote: > B> >> J> On Sunday, October 14, 2012 11:03:07 am Gleb Smirnoff wrote: > B> >> J> > Author: glebius > B> >> J> > Date: Sun Oct 14 15:03:06 2012 > B> >> J> > New Revision: 241546 > B> >> J> > URL: http://svn.freebsd.org/changeset/base/241546 > B> > > B> >> J> > Log: > B> >> J> > Fix defines in r241245. We actually don't define FreeBSD. > B> > > B> >> J> > Reported & tested by: Oleg Ginzburg > B> > > B> >> J> Seems like it should be using 'defined(__FreeBSD_version)' instead? > B> > > B> >> AFAIU, the construction which left after r241546 works fine. Anything > B> >> undefined resolves to zero, so in case of non-FreeBSD build we test > B> >> if (0 > 10000019) and this fails which is what we expect. > B> > > B> >> I have used this construction several times already without any side > B> >> effects. I have also seen it in some software in ports, where it works > B> >> okay, too. > B> > > B> > The C standard indeed permits this, but gcc -Wundef will warn about it. > B> > That compiler warning is in CWARNFLAGS in sys/conf/kern.mk so I suggest > B> > adding the 'defined(__FreeBSD_version) &&'. > B> > B> The C standard requires this, but some misconfigured compilers like > B> gcc -Wundef warn about it, and some non-C compilers like gcc -Wundef > B> -Werror fail on it. The bug is sometimes hidden by -Wno-system-headers, > B> but FreeBSD wants to detect bugs in system headers so it sets > B> -Wsystem-headers at WARNS >= 1, and then the buggy compilers find this > B> non-bug in system headers. The result is uglification of many system > B> headers to use if `defined(__FOO) && ...' instead of depending on this > B> standard and useful feature. > > Shouldn't we then remove -Wundef from CWARNFLAGS in kern.mk? There is some value to -Wundef if used properly: -Wundef Warn whenever an identifier which is not a macro is encountered in an #if directive, outside of defined. Such identifiers are replaced with zero. Thanks, -Garrett
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