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Date:   Fri, 2 Sep 2022 07:40:14 -0500
From:   Segher Boessenkool <segher@kernel.crashing.org>
To:     Christophe Leroy <christophe.leroy@csgroup.eu>
Cc:     Nathan Chancellor <nathan@kernel.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        kernel test robot <lkp@intel.com>,
        Arnd Bergmann <arnd@arndb.de>, Tom Rix <trix@redhat.com>,
        "llvm@lists.linux.dev" <llvm@lists.linux.dev>,
        Nick Desaulniers <ndesaulniers@google.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Nicholas Piggin <npiggin@gmail.com>,
        "patches@lists.linux.dev" <patches@lists.linux.dev>,
        "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH] powerpc/math_emu/efp: Include module.h
Message-ID: <20220902124014.GM25951@gate.crashing.org>
References: <20220831152014.3501664-1-nathan@kernel.org> <efd56f3e-bc8c-5da5-559d-e0bc6b21fa5b@csgroup.eu> <20220901194705.GI25951@gate.crashing.org> <ae2ee2d8-ec0a-d0ab-2c5a-b9a8c7579093@csgroup.eu>
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On Fri, Sep 02, 2022 at 08:43:49AM +0000, Christophe Leroy wrote:
> Le 01/09/2022 ? 21:47, Segher Boessenkool a ?crit?:
> > On Thu, Sep 01, 2022 at 05:41:33AM +0000, Christophe Leroy wrote:
> >> I think it would be worth a GCC bug report.
> > 
> > We need a stand-alone testcase for this.  When you have created one, at
> > least 98% of the time you discover the bug is in user code after all.
> > 
> > Which is a very good thing, it means the problem can be fixed simpler,
> > cheaper, and a lot faster :-)
> 
> Easy to reproduce with a .c file that has a single line:
> 
> non_existing_macro(xxx);

That was fast (and cheap and simple) :-)

> Apparently that's due to the -w option in arch/powerpc/math_emu/Makefile:
> 
> 	ccflags-y = -w
> 
> Was introduced by commit d2b194ed8208 ("powerpc/math-emu: Use kernel 
> generic math-emu code")
> 
> If I understand correctly it means 'ignore all warnings'. Then it seems 
> CLANG doesn't honor that request.

'-w'
     Inhibit all warning messages.

GCC's initial commit has this already (1992).


Segher