Re: [PATCH v2] Makefile.extrawarn: enable -Wmissing-variable-declarations for W=1

[kernel test robot <lkp@intel.com>]

Hi Nick,

kernel test robot noticed the following build errors:

[auto build test ERROR on 52a93d39b17dc7eb98b6aa3edb93943248e03b2f]

url:    https://github.com/intel-lab-lkp/linux/commits/Nick-Desaulniers/Makefile-extrawarn-enable-Wmissing-variable-declarations-for-W-1/20230808-005859
base:   52a93d39b17dc7eb98b6aa3edb93943248e03b2f
patch link:    https://lore.kernel.org/r/20230807-missing_proto-v2-1-3ae2e188bb0c%40google.com
patch subject: [PATCH v2] Makefile.extrawarn: enable -Wmissing-variable-declarations for W=1
config: arm64-randconfig-r013-20230807 (https://download.01.org/0day-ci/archive/20230808/202308081508.EI3CRzQo-lkp@intel.com/config)
compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project.git 4a5ac14ee968ff0ad5d2cc1ffa0299048db4c88a)
reproduce: (https://download.01.org/0day-ci/archive/20230808/202308081508.EI3CRzQo-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202308081508.EI3CRzQo-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from lib/test_bitops.c:9:
   In file included from include/linux/module.h:13:
   In file included from include/linux/stat.h:19:
   In file included from include/linux/time.h:60:
   In file included from include/linux/time32.h:13:
   In file included from include/linux/timex.h:67:
   In file included from arch/arm64/include/asm/timex.h:8:
   In file included from arch/arm64/include/asm/arch_timer.h:18:
   In file included from include/linux/smp.h:110:
   In file included from include/linux/preempt.h:79:
   In file included from arch/arm64/include/asm/preempt.h:6:
   In file included from include/linux/thread_info.h:60:
   In file included from arch/arm64/include/asm/thread_info.h:18:
>> arch/arm64/include/asm/stack_pointer.h:8:24: error: no previous extern declaration for non-static variable 'current_stack_pointer' [-Werror,-Wmissing-variable-declarations]
       8 | register unsigned long current_stack_pointer asm ("sp");
         |                        ^
   arch/arm64/include/asm/stack_pointer.h:8:10: note: declare 'static' if the variable is not intended to be used outside of this translation unit
       8 | register unsigned long current_stack_pointer asm ("sp");
         |          ^
   1 error generated.


vim +/current_stack_pointer +8 arch/arm64/include/asm/stack_pointer.h

a9ea0017ebe888 Mark Rutland 2016-11-03  4  
a9ea0017ebe888 Mark Rutland 2016-11-03  5  /*
a9ea0017ebe888 Mark Rutland 2016-11-03  6   * how to get the current stack pointer from C
a9ea0017ebe888 Mark Rutland 2016-11-03  7   */
a9ea0017ebe888 Mark Rutland 2016-11-03 @8  register unsigned long current_stack_pointer asm ("sp");
a9ea0017ebe888 Mark Rutland 2016-11-03  9  

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