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Date: Tue, 16 Apr 2024 14:44:30 +0200
From: "Arnd Bergmann" <arnd@arndb.de>
To: "Dan Carpenter" <dan.carpenter@linaro.org>
Cc: "Naresh Kamboju" <naresh.kamboju@linaro.org>,
 "open list" <linux-kernel@vger.kernel.org>, lkft-triage@lists.linaro.org,
 "Linux Regressions" <regressions@lists.linux.dev>,
 linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
 "Aneesh Kumar K.V" <aneesh.kumar@kernel.org>,
 "Anders Roxell" <anders.roxell@linaro.org>,
 "Kees Cook" <keescook@chromium.org>,
 "Niklas Schnelle" <schnelle@linux.ibm.com>,
 clang-built-linux <llvm@lists.linux.dev>,
 "Nick Desaulniers" <ndesaulniers@google.com>,
 "Nathan Chancellor" <nathan@kernel.org>, "Jeff Xu" <jeffxu@chromium.org>,
 "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>
Subject: Re: powerpc: io-defs.h:43:1: error: performing pointer arithmetic on a null
 pointer has undefined behavior [-Werror,-Wnull-pointer-arithmetic]
Content-Type: text/plain

On Tue, Apr 16, 2024, at 14:42, Dan Carpenter wrote:
> On Tue, Apr 16, 2024 at 01:55:57PM +0200, Arnd Bergmann wrote:
>> On Tue, Apr 16, 2024, at 13:01, Arnd Bergmann wrote:
>> > On Tue, Apr 16, 2024, at 11:32, Naresh Kamboju wrote:
>> >> The Powerpc clang builds failed due to following warnings / errors on the
>> >> Linux next-20240416 tag.
>> >>
>> >> Powerpc:
>> >>  - tqm8xx_defconfig + clang-17 - Failed
>> >>  - allnoconfig + clang-17 - Failed
>> >>  - tinyconfig + clang-17 - Failed
>> >>
>> >> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
>> >
>> > I'm not sure why this showed up now, but there is a series from
>> > in progress that will avoid this in the future, as the same
>> > issue is present on a couple of other architectures.
>> >
>> 
>> I see now, it was introduced by my patch to turn on -Wextra
>> by default. I had tested that patch on all architectures
>> with allmodconfig and defconfig, but I did not test any
>> powerpc configs with PCI disabled.
>
> I think this warning is clang specific as well...  (Maybe clang was
> included in all architectures but I'm not sure).

Yes, I did test with both gcc and clang where supported.

     Arnd