Re: [PATCH] gcc-plugins: require GCC

From: Masahiro Yamada
Date: Tue Aug 14 2018 - 09:27:07 EST


2018-08-14 6:29 GMT+09:00 Stefan Agner <stefan@xxxxxxxx>:
> On 13.08.2018 22:18, Kees Cook wrote:
>> On Mon, Aug 13, 2018 at 1:10 PM, Kees Cook <keescook@xxxxxxxxxxxx> wrote:
>>> On Mon, Aug 13, 2018 at 12:38 AM, Masahiro Yamada
>>> <yamada.masahiro@xxxxxxxxxxxxx> wrote:
>>>> 2018-08-11 18:48 GMT+09:00 Stefan Agner <stefan@xxxxxxxx>:
>>>>> Unsurprisingly GCC plugins require GCC as a compiler. This avoids
>>>>> GCC plugins being selectable when using clang.
>>>>>
>>>>> Signed-off-by: Stefan Agner <stefan@xxxxxxxx>
>>>>> ---
>>>>> arch/Kconfig | 2 +-
>>>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/arch/Kconfig b/arch/Kconfig
>>>>> index 1aa59063f1fd..8c693a837ed7 100644
>>>>> --- a/arch/Kconfig
>>>>> +++ b/arch/Kconfig
>>>>> @@ -422,7 +422,7 @@ config HAVE_GCC_PLUGINS
>>>>>
>>>>> menuconfig GCC_PLUGINS
>>>>> bool "GCC plugins"
>>>>> - depends on HAVE_GCC_PLUGINS
>>>>> + depends on HAVE_GCC_PLUGINS && CC_IS_GCC
>>>>> depends on PLUGIN_HOSTCC != ""
>>>>> help
>>>>> GCC plugins are loadable modules that provide extra features to the
>>>>> --
>>>>> 2.18.0
>>>>>
>>>>
>>>> I guess the more correct way is to fix
>>>> scripts/gcc-plugin.sh
>>>>
>>>> This shell script should exit 0
>>>> only when GCC plugin is supported.
>>>
>>> I'm of two minds: we already have the gcc test in Kconfig so we might
>>> want to avoid redundant checks, but maybe the script should be a
>>> "complete" test. I guess the latter. I will send a patch.
>>
>> Actually, how about we do the test in Kconfig, but ahead of the
>> script? That will reduce redundancy:
>>
>> diff --git a/arch/Kconfig b/arch/Kconfig
>> index 1aa59063f1fd..18f518624e41 100644
>> --- a/arch/Kconfig
>> +++ b/arch/Kconfig
>> @@ -409,7 +409,7 @@ preferred-plugin-hostcc := $(if-success,[
>> $(gcc-version) -ge 40800 ],$(HOSTCXX),
>>
>> config PLUGIN_HOSTCC
>> string
>> - default "$(shell,$(srctree)/scripts/gcc-plugin.sh
>> "$(preferred-plugin-hostcc)" "$(HOSTCXX)" "$(CC)")"
>> + default "$(shell,$(srctree)/scripts/gcc-plugin.sh
>> "$(preferred-plugin-hostcc)" "$(HOSTCXX)" "$(CC)")" if CC_IS_GCC
>> help
>> Host compiler used to build GCC plugins. This can be $(HOSTCXX),
>> $(HOSTCC), or a null string if GCC plugin is unsupported.
>
> I like this better. A script which is called gcc-plugin.sh should only
> be called if gcc is used...
>

This does not work like that.

$(shell,$(srctree)/scripts/gcc-plugin.sh "$(preferred-plugin-hostcc)"
"$(HOSTCXX)" "$(CC)")

is expanded in the parse stage regardless of CC_IS_GCC.




If nobody comes up with a better way, I am fine with this.

Reviewed-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>




> --
> Stefan
>
>>
>>
>> -Kees



--
Best Regards
Masahiro Yamada