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From:   Masahiro Yamada <yamada.masahiro@socionext.com>
Date:   Wed, 28 Mar 2018 20:52:01 +0900
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Subject: Re: [PATCH v2 14/21] kconfig: add CC_IS_CLANG and CLANG_VERSION
To:     Kees Cook <keescook@chromium.org>
Cc:     linux-kbuild <linux-kbuild@vger.kernel.org>,
        Sam Ravnborg <sam@ravnborg.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Ulf Magnusson <ulfalizer@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Randy Dunlap <rdunlap@infradead.org>,
        "Luis R . Rodriguez" <mcgrof@kernel.org>,
        Nicolas Pitre <nico@linaro.org>,
        LKML <linux-kernel@vger.kernel.org>
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2018-03-28 20:22 GMT+09:00 Kees Cook <keescook@chromium.org>:
> On Mon, Mar 26, 2018 at 10:29 PM, Masahiro Yamada
> <yamada.masahiro@socionext.com> wrote:
>> This will be useful to describe the clang version dependency.
>>
>> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
>
> One aspect of clang version checking that may be "weird" (and likely
> won't be meaningful for very long as we're about to raise the minimum
> gcc version), is that clang claims to be gcc version 4.2 if you look
> at #defines. This is already handled in compiler.h, but may be weird
> in Kconfig.
>


CONFIG_CLANG_VERSION gives me real clang version.


$ clang --version
clang version 7.0.0 (http://llvm.org/git/clang.git
f1d1f4c4591e81cfa80034df094b26d7eb4fa92b)
(http://llvm.org/git/llvm.git
d157ba2f80790d23d717c4ff3f5bee30d98d6a51)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/masahiro/toolchains/clang-latest/bin

$ make CC=clang defconfig
*** Default configuration is based on 'x86_64_defconfig'
#
# configuration written to .config
#
$ grep  CLANG_VERSION .config
CONFIG_CLANG_VERSION=70000


I am just porting
https://patchwork.kernel.org/patch/10085765/
to Kconfig.


-- 
Best Regards
Masahiro Yamada