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Subject: Re: [PATCH] ubsan: don't mark __ubsan_handle_builtin_unreachable as
 noreturn
To:     Olof Johansson <olof@lixom.net>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Nicolas Pitre <nico@linaro.org>,
        Andi Kleen <ak@linux.intel.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
References: <20180202154813.1625742-1-arnd@arndb.de>
 <d77f9a8a-0bb2-50a3-68e3-b4f4173645bc@virtuozzo.com>
 <CAK8P3a124Jdza9YbgOHECC2owpx_HmOuDMWtotxuC2-F9L9Cgg@mail.gmail.com>
 <00813389-daf0-a97f-8642-cb4e7a62fa27@virtuozzo.com>
 <CAOesGMi-vkYPDrL2drJ70zf3_xTMWrsfPoW68TkiRJCj8uWBLg@mail.gmail.com>
From:   Andrey Ryabinin <aryabinin@virtuozzo.com>
Message-ID: <cca8985f-8279-7bd8-3ebe-f2f79cd98b91@virtuozzo.com>
Date:   Wed, 7 Nov 2018 17:44:27 +0300
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On 11/03/2018 12:27 AM, Olof Johansson wrote:
> On Mon, Feb 5, 2018 at 2:31 AM Andrey Ryabinin <aryabinin@virtuozzo.com> wrote:
>>
>> On 02/05/2018 01:15 PM, Arnd Bergmann wrote:
>>> On Mon, Feb 5, 2018 at 10:02 AM, Andrey Ryabinin
>>> <aryabinin@virtuozzo.com> wrote:
>>>>
>>>>
>>>> On 02/02/2018 06:47 PM, Arnd Bergmann wrote:
>>>>> gcc-8 complains about the prototype for this function:
>>>>>
>>>>> lib/ubsan.c:432:1: error: ignoring attribute 'noreturn' in declaration of a built-in function '__ubsan_handle_builtin_unreachable' because it conflicts with attribute 'const' [-Werror=attributes]
>>>>>
>>>>
>>>> That's actually a bug in GCC. In GCC __ubsan_handle_builtin_unreachable declared
>>>> with 'noreturn' and 'const' attributes:
>>>>
>>>> DEF_SANITIZER_BUILTIN(BUILT_IN_UBSAN_HANDLE_BUILTIN_UNREACHABLE,
>>>>                       "__ubsan_handle_builtin_unreachable",
>>>>                       BT_FN_VOID_PTR,
>>>>                       ATTR_COLD_CONST_NORETURN_NOTHROW_LEAF_LIST)
>>>>
>>>>
>>>> But const attribute doesn't make any sense for function that returns void or doesn't return at all.
>>>> Given that gcc-8 has not released yet, it would be better to fix this bug there.
>>>
>>> Ok. Should I open a gcc bug, or will you take care of it?
>>>
>>
>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84210
> 
> 8.2.0 still shows this, and there's been no movement on that bug. How
> about we pick up this patch until it's been resolved?
> 

Sure, I'll add info about GCC bug in changelog and resend the patch.

> 
> -Olof
>