Re: [arm-platforms:hack/m1-pmu 8/8] drivers/perf/apple_m1_cpu_pmu.c:100:32: warning: initializer overrides prior initialization of this subobject

[Marc Zyngier <maz@kernel.org>]

On 2021-11-14 08:25, kernel test robot wrote:
> tree:
> https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git
> hack/m1-pmu
> head:   a905c66ae0b391425e9ad7f261ad7b4c33af2c07
> commit: a905c66ae0b391425e9ad7f261ad7b4c33af2c07 [8/8] drivers/perf:
> Add Apple icestorm/firestorm CPU PMU driver
> config: arm64-randconfig-r036-20211114 (attached as .config)
> compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project
> c3dddeeafb529e769cde87bd29ef6271ac6bfa5c)
> reproduce (this is a W=1 build):
>         wget
> https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross
> -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # install arm64 cross compiling tool for clang build
>         # apt-get install binutils-aarch64-linux-gnu
>         #
> https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/commit/?id=a905c66ae0b391425e9ad7f261ad7b4c33af2c07
>         git remote add arm-platforms
> https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git
>         git fetch --no-tags arm-platforms hack/m1-pmu
>         git checkout a905c66ae0b391425e9ad7f261ad7b4c33af2c07
>         # save the attached .config to linux build tree
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1
> ARCH=arm64
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
> 
> All warnings (new ones prefixed by >>):
> 
>>> drivers/perf/apple_m1_cpu_pmu.c:100:32: warning: initializer 
>>> overrides prior initialization of this subobject 
>>> [-Winitializer-overrides]
>            [M1_PMU_PERFCTR_UNKNOWN_01]     = BIT(7),
>                                              ^~~~~~
>    include/vdso/bits.h:7:19: note: expanded from macro 'BIT'
>    #define BIT(nr)                 (UL(1) << (nr))
>                                    ^~~~~~~~~~~~~~~
>    drivers/perf/apple_m1_cpu_pmu.c:99:32: note: previous initialization 
> is here
>            [0 ... M1_PMU_PERFCTR_LAST]     = ANY_BUT_0_1,
>                                              ^~~~~~~~~~~

Oh please, not that thing again. I've commented on this many times,
and this warning is just bogus. Initialisation override is a necessity,
and working around this warning leads to something that is far less
maintainable, and thus more *dangerous* than this.

I really wish this warning was simply turned off, because it only
leads to the robot emails to be ignored do to the number of false 
positives.

         M.
-- 
Jazz is not dead. It just smells funny...

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