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From: Nick Desaulniers <ndesaulniers@google.com>
Date: Mon, 11 Oct 2021 13:18:34 -0700
Message-ID: <CAKwvOd=-VQHxp+Ar27LyqPMmMMt-mRu+32uD50dk6eWMfAj1VQ@mail.gmail.com>
Subject: Re: [arm-platforms:timers/tval-ectomy 2/17] drivers/clocksource/arm_arch_timer.c:156:3:
 warning: variable 'val' is used uninitialized whenever switch default is taken
To: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc: Marc Zyngier <maz@kernel.org>, kernel test robot <lkp@intel.com>, llvm@lists.linux.dev, 
	kbuild-all@lists.01.org, Linux ARM <linux-arm-kernel@lists.infradead.org>, 
	Oliver Upton <oupton@google.com>, Mark Rutland <mark.rutland@arm.com>
Content-Type: text/plain; charset="UTF-8"

On Sun, Oct 10, 2021 at 3:55 AM Miguel Ojeda
<miguel.ojeda.sandonis@gmail.com> wrote:
>
> On Sun, Oct 10, 2021 at 11:37 AM Marc Zyngier <maz@kernel.org> wrote:
> >
> > I think the problem squarely lies with the compiler (or the
> > way it interprets the BUILD_BUG helper). If it cannot see that
> > BUILD_BUG() trumps the control flow analysis, then this warning
> > is totally useless.
>
> The fake, generated `__compiletime_assert` should be annotated
> `__noreturn`. That gives enough information to the compiler to avoid
> the warning: https://godbolt.org/z/x1v69jjYY

SGTM, please do.

>
> And we should also move `__compiletime_{error,warning}` to compiler
> attributes since Clang trunk has it now, so that we catch the error
> earlier: https://godbolt.org/z/jd8Eb9Mf1

Didn't I send a patch for that?
b83a908498d68fafca931e1276e145b339cac5fb
is in mainline.
-- 
Thanks,
~Nick Desaulniers