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From:   Masahiro Yamada <yamada.masahiro@socionext.com>
Date:   Fri, 30 Aug 2019 02:18:14 +0900
Message-ID: <CAK7LNATZSLYMW3NaEgm=r7EiHwLnxjtaogm_CRHZYgcBLVRb-w@mail.gmail.com>
Subject: Re: [PATCH] kbuild: Do not enable -Wimplicit-fallthrough for clang
 for now
To:     Nick Desaulniers <ndesaulniers@google.com>
Cc:     Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
        Nathan Chancellor <natechancellor@gmail.com>,
        Michal Marek <michal.lkml@markovi.net>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>,
        Nathan Huckleberry <nhuck@google.com>,
        Joe Perches <joe@perches.com>
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On Thu, Aug 29, 2019 at 2:44 AM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> On Wed, Aug 28, 2019 at 10:39 AM Nick Desaulniers
> <ndesaulniers@google.com> wrote:
> >
> > On Wed, Aug 28, 2019 at 9:45 AM Miguel Ojeda
> > <miguel.ojeda.sandonis@gmail.com> wrote:
> > >
> > > On Wed, Aug 28, 2019 at 6:21 PM Masahiro Yamada
> > > <yamada.masahiro@socionext.com> wrote:
> > > >
> > > > Applied to linux-kbuild. Thanks.
> > > >
> > > > (If other clang folks give tags, I will add them later.)
> > >
> > > Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
> >
> > I verified that GCC didn't get support for -Wimplicit-fallthrough
> > until GCC ~7.1 release, so the cc-option guard is still required.
> > Acked-by: Nick Desaulniers <ndesaulniers@google.com>
> > Thanks for the patch Nathan.
>
> Also, there's an inconsistency between Makefile vs
> scripts/Makefile.extrawarn that's been bugging me: it seems we enable
> GCC only flags in Makefile, then disable certain Clang flags in
> scripts/Makefile.extrawarn.


All the flags listed in scripts/Makefile.extrawarn depend on W= option.
The options in Makefile are passed irrespective of W=.

There is no inconsistency.


> Not necessary to fix here and now, but I
> hope one day to have one file that has all of the compiler specific
> flags in one place (maybe its own file), so I only have to look in one
> place.  I know, I know, "patches welcome." ;)
>
> --
> Thanks,
> ~Nick Desaulniers


-- 
Best Regards
Masahiro Yamada