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From:   Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Date:   Sun, 26 Aug 2018 19:37:28 +0200
Message-ID: <CANiq72kV0srrjF8CfzUntFT7KcdNQfnP8rF3RG44WR4j89uhjA@mail.gmail.com>
Subject: Re: [PATCH] include/linux/compiler*.h: make compiler-*.h mutually exclusive
To:     Joe Perches <joe@perches.com>
Cc:     Nick Desaulniers <ndesaulniers@google.com>,
        Kees Cook <keescook@chromium.org>, asmadeus@codewreck.org,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Arnd Bergmann <arnd@arndb.de>, dwmw@amazon.co.uk,
        LKML <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Will Deacon <will.deacon@arm.com>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Ingo Molnar <mingo@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        daniel@iogearbox.net, "H. Peter Anvin" <hpa@zytor.com>
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Hi all,

On Fri, Aug 24, 2018 at 1:31 AM, Joe Perches <joe@perches.com> wrote:
> On Thu, 2018-08-23 at 16:12 -0700, Nick Desaulniers wrote:
>> On Thu, Aug 23, 2018 at 2:19 PM Joe Perches <joe@perches.com> wrote:
>> >
>> > On Thu, 2018-08-23 at 14:03 -0700, Nick Desaulniers wrote:
>> > > Not this case; it's how we get gnu89 semantics for `extern inline` is
>> > > not compiler specific (therefor should not go in a compiler specific
>> > > header).
>> >
>> > It's not possible to know that compilers support what
>> > __attribute__((<foo>)) and at what version that support
>> > exists unless it is specified somewhere.
>>
>> __has_attribute:
>> https://clang.llvm.org/docs/LanguageExtensions.html#has-attribute
>>
>> The release notes of GCC-5 mention __has_attribute.
>> https://gcc.gnu.org/gcc-5/changes.html
>
> So not available in the now minimum supported gcc 4.6?
>

We can workaround that until we have 5 as the minimum. I have tried
and the result is quite nice.

Sending the patch in a few moments -- compile-testing for a while
allmodconfig on both 4.6 and 8.2...

Cheers,
Miguel