Re: [PATCH 2/2] kbuild: clang: Disable the 'duplicate-decl-specifier' warning
From: Arnd Bergmann
Date: Wed Jun 21 2017 - 06:12:08 EST
On Wed, Jun 21, 2017 at 11:11 AM, Masahiro Yamada
> 2017-05-24 17:21 GMT+09:00 Arnd Bergmann <arnd@xxxxxxxx>:
>> On Wed, May 24, 2017 at 2:04 AM, Matthias Kaehlcke <mka@xxxxxxxxxxxx> wrote:
>>> El Wed, May 17, 2017 at 11:45:29AM -0700 Matthias Kaehlcke ha dit:
>>>> El Wed, May 17, 2017 at 09:35:57AM +0200 Arnd Bergmann ha dit:
>>>> > On Tue, May 16, 2017 at 11:41 PM, Doug Anderson <dianders@xxxxxxxxxxxx> wrote:
>>> It seems the duplicate-decl-specifier warning targets specifically C89:
>>> "The same type qualifier shall not appear more than once in the same
>>> specifier list or qualifier list, either directly or via one or more
>>> C89 (6.5.3)
>>> gcc also raises a warning when '-pedantic' is specified and
>>> -std=gnu89/c89 (or unspecified), but not with -std=gnu99/c99.
>>> This bug might help to shed more light on this:
>> I also notice that neither compiler differentiates between a)
>> typedef const int cint;
>> const cint i;
>> and b)
>> const int i;
>> const typeof(a) j;
>> I would have expected a warning for a) but not b), but both 'clang --std=gnu89'
>> and 'gcc --pedantic --std=gnu89' warn about both of b as well, and don't warn
>> for newer standards.
> I think we agreed to apply 1/2.
> How about 2/2?
> I think we mostly discussed preferable behavior of -Wduplicate-decl-specifier,
> but we did not come up with an idea to solve the problem for
> already shipped clang versions.
> (BTW, we have not defined the minimal supported version of clang yet.)
I see that container_of() has been modified in linux-next and no longer adds
the 'const' keyword, do we actually still need the patch?