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From: Uros Bizjak <ubizjak@gmail.com>
Date: Mon, 4 Mar 2024 06:42:57 +0100
Message-ID: <CAFULd4aEe2KU=UXEt2=GeLQq2uTSFvydBiwAdSa7B6T61Am=5w@mail.gmail.com>
Subject: Re: arch/x86/include/asm/processor.h:698:16: sparse: sparse:
 incorrect type in initializer (different address spaces)
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>, kernel test robot <lkp@intel.com>, 
	oe-kbuild-all@lists.linux.dev, linux-kernel@vger.kernel.org, 
	Arjan van de Ven <arjan@linux.intel.com>, x86@kernel.org, 
	Luc Van Oostenryck <luc.vanoostenryck@gmail.com>, 
	Sparse Mailing-list <linux-sparse@vger.kernel.org>, "Paul E. McKenney" <paulmck@kernel.org>
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On Mon, Mar 4, 2024 at 12:49=E2=80=AFAM Thomas Gleixner <tglx@linutronix.de=
> wrote:
>
> On Sun, Mar 03 2024 at 21:24, Uros Bizjak wrote:
> > On Sun, Mar 3, 2024 at 9:21=E2=80=AFPM Uros Bizjak <ubizjak@gmail.com> =
wrote:
> >> On Sun, Mar 3, 2024 at 9:10=E2=80=AFPM Thomas Gleixner <tglx@linutroni=
x.de> wrote:
> >> > That's so sad because it would provide us compiler based __percpu
> >> > validation.
> >>
> >> Unfortunately, the c compiler can't strip qualifiers, so typeof() is
> >> of limited use also when const and volatile qualifiers are used.
> >> Perhaps some extension could be introduced to c standard to provide an
> >> unqualified type, e.g. typeof_unqual().
> >
> > Oh, there is one in C23 [1].
>
> Yes. I found it right after ranting.
>
> gcc >=3D 14 and clang >=3D 16 have support for it of course only when add=
ing
> -std=3Dc2x to the command line.
>
> Sigh. The name space qualifiers are non standard and then the thing
> which makes them more useful is hidden behind a standard.

With GCC, you can use __typeof_unqual__ (please note underscores)
without -std=3Dc2x [1]:

"... Alternate spelling __typeof_unqual__ is available in all C modes
and provides non-atomic unqualified version of what __typeof__
operator returns..."

Please also see the example in my last post. It can be compiled without -st=
d=3D...

[1] https://gcc.gnu.org/onlinedocs/gcc/Typeof.html

Uros.