linux-kernel - Re: [PATCH v5 24/31] kconfig: add CC_IS_GCC and GCC

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Date:   Tue, 05 Jun 2018 10:37:27 +0200
From:   Stefan Agner <stefan@...er.ch>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Kees Cook <keescook@...omium.org>,
        Nicholas Piggin <npiggin@...il.com>,
        "Luis R . Rodriguez" <mcgrof@...e.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Ulf Magnusson <ulfalizer@...il.com>,
        Sam Ravnborg <sam@...nborg.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-kbuild-owner@...r.kernel.org
Subject: Re: [PATCH v5 24/31] kconfig: add CC_IS_GCC and GCC_VERSION

On 05.06.2018 08:27, Masahiro Yamada wrote:
> 2018-06-05 14:50 GMT+09:00 Stefan Agner <stefan@...er.ch>:
>> On 05.06.2018 02:07, Masahiro Yamada wrote:
>>> Hi Stefan
>>>
>>> 2018-06-05 6:49 GMT+09:00 Stefan Agner <stefan@...er.ch>:
>>>> Hi Masahiro,
>>>>
>>>> On 28.05.2018 11:22, Masahiro Yamada wrote:
>>>>> This will be useful to specify the required compiler version,
>>>>> like this:
>>>>>
>>>>> config FOO
>>>>>         bool "Use Foo"
>>>>>         depends on GCC_VERSION >= 40800
>>>>>         help
>>>>>           This feature requires GCC 4.8 or newer.
>>>>>
>>>>
>>>> I tried using CC_IS_GCC today while using clang. It seems that it is set
>>>> to y despite I am using CC=clang.
>>>>
>>>> .config looks like this after config:
>>>>
>>>> ...
>>>> CONFIG_CC_IS_GCC=y
>>>> CONFIG_GCC_VERSION=40201
>>>> CONFIG_CC_IS_CLANG=y
>>>> CONFIG_CLANG_VERSION=60000
>>>> ...
>>>>
>>>>
>>>> I am using clang 6.0.0 on Arch Linux, which seems to return a version
>>>> when using gcc-version.sh:
>>>> ./scripts/gcc-version.sh clang | sed 's/^0*//'
>>>> 402
>>>>
>>>> I guess that should not be the case?
>>>>
>>>
>>>
>>> What will 'clang --version' print on your machine?
>>
>> $ clang --version
>> clang version 6.0.0 (tags/RELEASE_600/final)
>> Target: x86_64-pc-linux-gnu
>> Thread model: posix
>> InstalledDir:
>> /home/ags/gcc-linaro-7.2.1-2017.11-x86_64_arm-linux-gnueabihf/bin
>>
>> I use a symlink to clang in my cross compiler toolchain, that is why
>> InstalledDir points to a GCC toolchain.
>>
> 
> Ah, I see.
> 
> 
> I will fix it up like follows:
> 
> 
> diff --git a/init/Kconfig b/init/Kconfig
> index e5a0d89..efc43c6 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -9,7 +9,7 @@ config DEFCONFIG_LIST
>         default "arch/$(ARCH)/defconfig"
> 
>  config CC_IS_GCC
> -       def_bool $(success,$(CC) --version | grep -q gcc)
> +       def_bool $(success,$(CC) --version | head -n 1 | grep -q gcc)

Yes that works for me:

...
CONFIG_GCC_VERSION=0                                                    
                                                                   
CONFIG_CC_IS_CLANG=y                                                    
                                                                   
CONFIG_CLANG_VERSION=60000
...

--
Stefan

> 
>  config GCC_VERSION
>         int
> @@ -17,7 +17,7 @@ config GCC_VERSION
>         default 0
> 
>  config CC_IS_CLANG
> -       def_bool $(success,$(CC) --version | grep -q clang)
> +       def_bool $(success,$(CC) --version | head -n 1 | grep -q clang)
> 
>  config CLANG_VERSION
>         int
> 
> 
> 
> 
> Best Regards
> Masahiro Yamada