[PATCH v2 4/5] powerpc: Fix duplicate const clang warning in user access code

[Christophe LEROY]

Le 19/09/2018 à 09:45, Joel Stanley a écrit :
> On Sat, 15 Sep 2018 at 03:27, Nick Desaulniers <ndesaulniers at google.com> wrote:
>>
>> On Thu, Sep 13, 2018 at 9:07 PM Joel Stanley <joel at jms.id.au> wrote:
>>>
>>> From: Anton Blanchard <anton at samba.org>
>>>
>>> This re-applies b91c1e3e7a6f which was reverted in f2ca80905929
>>> d466f6c5cac1 f84ed59a612d (powerpc/sparse: Constify the address pointer
>>> ...").
>>>
>>> We see a large number of duplicate const errors in the user access
>>> code when building with llvm/clang:
>>>
>>>    include/linux/pagemap.h:576:8: warning: duplicate 'const' declaration specifier
>>>        [-Wduplicate-decl-specifier]
>>>          ret = __get_user(c, uaddr);
>>>
>>> The problem is we are doing const __typeof__(*(ptr)), which will hit the
>>> warning if ptr is marked const.
>>>
>>> Removing const does not seem to have any effect on GCC code generation.
>>
>> I wouldn't expect it to for a local variable with such localized
>> usage.  I myself am quite liberal in applying `const` to everything,
>> so I will try to fix this in Clang as well, but this should silence
>> the warning for users of older versions of Clang and results in no
>> functional change.
>> Reviewed-by: Nick Desaulniers <ndesaulniers at google.com>
> 
> Nick has written a clang patch that suppresses the warning in the same
> way as GCC. Assuming it gets merged, as we depend on clang-8 we could
> chose to not merge the kernel patch.
> 
> https://reviews.llvm.org/D52248
> 

Seems like Michael has merged this patch anyway.

Christophe