linux-kernel - RE: [PATCH next v2 2/5] minmax: Allow min()/max()/clamp() if the arguments have the same signedness.

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Message-ID: <a576676d66284659bc91afe93d2b0159@AcuMS.aculab.com>
Date:   Tue, 1 Aug 2023 08:45:10 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'kernel test robot' <lkp@...el.com>,
        "'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>,
        'Andy Shevchenko' <andriy.shevchenko@...ux.intel.com>,
        'Andrew Morton' <akpm@...ux-foundation.org>,
        "'Matthew Wilcox (Oracle)'" <willy@...radead.org>,
        'Christoph Hellwig' <hch@...radead.org>,
        "'Jason A. Donenfeld'" <Jason@...c4.com>
CC:     "llvm@...ts.linux.dev" <llvm@...ts.linux.dev>,
        "oe-kbuild-all@...ts.linux.dev" <oe-kbuild-all@...ts.linux.dev>,
        "Linux Memory Management List" <linux-mm@...ck.org>
Subject: RE: [PATCH next v2 2/5] minmax: Allow min()/max()/clamp() if the
 arguments have the same signedness.

From: kernel test robot
> Sent: 31 July 2023 22:44
> 
> kernel test robot noticed the following build errors:
> 
> [auto build test ERROR on akpm-mm/mm-everything]
> [also build test ERROR on linus/master crng-random/master v6.5-rc4 next-20230731]
> [cannot apply to next-20230728]
...
> compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project.git
> f28c006a5895fc0e329fe15fead81e37457cb1d1)
> reproduce: (https://download.01.org/0day-ci/archive/20230801/202308010559.SEtfkzQU-
> lkp@...el.com/reproduce)
> 
....
> >> drivers/gpu/drm/drm_modes.c:2474:15: error: static_assert expression is not an integral constant
> expression
>                    extra_ptr = max(bpp_end_ptr, refresh_end_ptr);
>                                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is really a bug in clang - fixed in 16.0.0.
In C (but probably not C++) '(void *)1' should be a compile-time constant.
Will be fixed in v3 of the patch.

	David

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