Date: Fri, 23 Dec 2011 00:46:23 +0000 From: Alexander Best <arundel@freebsd.org> To: Dimitry Andric <dim@FreeBSD.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r228822 - head/sys/conf Message-ID: <20111223004623.GA63192@freebsd.org> In-Reply-To: <20111223004341.GA59309@freebsd.org> References: <201112230023.pBN0NbRJ040161@svn.freebsd.org> <20111223004341.GA59309@freebsd.org>
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On Fri Dec 23 11, Alexander Best wrote: > On Fri Dec 23 11, Dimitry Andric wrote: > > Author: dim > > Date: Fri Dec 23 00:23:37 2011 > > New Revision: 228822 > > URL: http://svn.freebsd.org/changeset/base/228822 > > > > Log: > > When building the kernel with clang, it produces several warnings which > > might be useful in some cases, but which are not severe enough to error > > out the whole kernel build. Display them anyway, so there is at least > > some incentive to fix them eventually. > > > > Start with -Wtautological-compare warnings. These usually occur when > > people check if unsigned quantities are negative, or similar cases. To > > clean these up would be painful, and might give problems if the base > > type which is compared against changes to signed later on. > > ... or is signed on one arch, but unsigned on another. ;) > > any reason you add -Wno-error-tautological-compare to CWARNFLAGS seperately > and not in the upper CWARNFLAGS?= definition? the way you implemented it here > makes it impossible to specify custom CWARNFLAGS, where users might want to > keep -Wtautological-compare as an error and not turn it into a warning. > > i already sent you the following patch, which takes a different approach > towards the issue you're trying to solve. > > of course it's debatable, whether -Wno-error-tautological-compare should be > mandatory, or not. -fno-strict-aliasing e.g. is a flag which also gets appended > (only to COPTFLAGS) even when users set custom COPTFLAGS > > cheers. > alex > > > > > MFC after: 1 week > > > > Modified: > > head/sys/conf/kern.mk > > > > Modified: head/sys/conf/kern.mk > > ============================================================================== > > --- head/sys/conf/kern.mk Fri Dec 23 00:19:17 2011 (r228821) > > +++ head/sys/conf/kern.mk Fri Dec 23 00:23:37 2011 (r228822) > > @@ -19,6 +19,10 @@ NO_WCONSTANT_CONVERSION= -Wno-constant-c > > NO_WARRAY_BOUNDS= -Wno-array-bounds > > NO_WSHIFT_COUNT_NEGATIVE= -Wno-shift-count-negative > > NO_WSHIFT_COUNT_OVERFLOW= -Wno-shift-count-overflow > > +# Several other warnings which might be useful in some cases, but not severe > > +# enough to error out the whole kernel build. Display them anyway, so there is > > +# some incentive to fix them eventually. > > +CWARNFLAGS+= -Wno-error-tautological-compare > > .endif > > > > # > Index: conf/kern.mk > =================================================================== > --- conf/kern.mk (revision 228556) > +++ conf/kern.mk (working copy) > @@ -1,12 +1,24 @@ > # $FreeBSD$ > > # > +# Clang implies -Wtautological-compare when -Wall was specified. Since this > +# will produce errors for valid code, we need to disable -Wtautological-compare. > +# GCC doesn't recognize this warning, nor does it have a similar warning flag. > +# However specifying -Wextra implies -Wtautological-compare semantics. > +# > +.if ${CC:T:Mclang} == "clang" > +NO_TAUTCOMP= -Wno-tautological-compare s/-Wno-tautological-compare/-Wno-error-tautological-compare/ sorry. > +.else > +NO_TAUTCOMP= > +.endif > + > +# > # Warning flags for compiling the kernel and components of the kernel: > # > CWARNFLAGS?= -Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes \ > -Wmissing-prototypes -Wpointer-arith -Winline -Wcast-qual \ > -Wundef -Wno-pointer-sign -fformat-extensions \ > - -Wmissing-include-dirs -fdiagnostics-show-option > + -Wmissing-include-dirs -fdiagnostics-show-option ${NO_TAUTCOMP} > # > # The following flags are next up for working on: > # -Wextra
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