linux-kernel - Re: [PATCH v2] kbuild, LLVMLinux: Supress warnings unless W=1-3

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Date:	Thu, 31 Jul 2014 21:07:01 -0700
From:	Behan Webster <behanw@...verseincode.com>
To:	Michal Marek <mmarek@...e.cz>
CC:	linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
	dwmw2@...radead.org,
	Jan-Simon Möller <dl9pf@....de>,
	Mark Charlebois <charlebm@...il.com>, bp@...en8.de
Subject: Re: [PATCH v2] kbuild, LLVMLinux: Supress warnings unless W=1-3

On 07/31/14 13:46, Michal Marek wrote:
> Dne 31.7.2014 18:12, Behan Webster napsal(a):
>> On 07/31/14 01:18, Michal Marek wrote:
>>> Dne 31.7.2014 06:16, behanw@...verseincode.com napsal(a):
>>>> @@ -55,6 +45,18 @@ warning-3 += -Wswitch-default
>>>>    warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
>>>>    warning-3 += $(call cc-option, -Wvla)
>>>>    +ifeq ($(COMPILER),clang)
>>>> +ifndef $(W)
>>>> +KBUILD_CFLAGS += $(call cc-disable-warning, initializer-overrides)
>>>> +KBUILD_CFLAGS += $(call cc-disable-warning, unused-value)
>>>> +KBUILD_CFLAGS += $(call cc-disable-warning, format)
>>>> +KBUILD_CFLAGS += $(call cc-disable-warning, unknown-warning-option)
>>>> +KBUILD_CFLAGS += $(call cc-disable-warning, sign-compare)
>>>> +KBUILD_CFLAGS += $(call cc-disable-warning, format-zero-length)
>>>> +KBUILD_CFLAGS += $(call cc-disable-warning, uninitialized)
>>>> +endif
>>>> +endif
>>>> +
>>> Please remove this part, it has no effect. I assume that if it works for
>>> you, these warning are not as annoying so they do not need to be
>>> disabled?
>> Actually they are annoying, that's why they're disabled normally. Most
>> of them complain about practices which are relatively common in kernel
>> code.
>>
>> clang warns about a lot more things than gcc does. It means that code
>> which compiles cleanly in gcc often doesn't with clang. This cuts out
>> the warnings which are unlikely to to be fixed in kernel code anytime
>> soon, but which are probably worth exposing when W=1 is used.
>>
>> This part of the patch explicitly deals with complaints from some in the
>> kernel community that clang is too noisy with kernel code.
>>
>> This part of the patch needs to be somewhere. This seemed the best place.
> You placed it inside a branch that is only evaluated when W= is given.
Hmm. You're right. Will fix.

Behan

-- 
Behan Webster
behanw@...verseincode.com

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