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Message-ID: <ca208328-f632-3285-2f57-83dded6bd930@infradead.org>
Date:   Fri, 8 Apr 2022 18:54:09 -0700
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Subject: Re: [PATCHv1] kbuild: support W=e to make build abort in case of
 warning
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To:     Masahiro Yamada <masahiroy@kernel.org>
Cc:     Nick Desaulniers <ndesaulniers@google.com>,
        Yann Droneaud <ydroneaud@opteya.com>,
        Michal Marek <michal.lkml@markovi.net>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>
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From:   Randy Dunlap <rdunlap@infradead.org>
In-Reply-To: <CAK7LNAS6ap9dR=kzRgQgt+d7FBBbVrwEqGU9g_pFD+nzMUt+gQ@mail.gmail.com>
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On 4/8/22 18:47, Masahiro Yamada wrote:
> On Sat, Apr 9, 2022 at 5:36 AM Randy Dunlap <rdunlap@infradead.org> wrote:
>>
>>
>>
>> On 4/8/22 13:29, Nick Desaulniers wrote:
>>> On Fri, Apr 8, 2022 at 4:06 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
>>>>
>>>> On Fri, Apr 8, 2022 at 5:46 PM Yann Droneaud <ydroneaud@opteya.com> wrote:
>>>>>
>>>>> When developing new code/feature, CONFIG_WERROR is most
>>>>> often turned off, especially for people using make W=12 to
>>>>> get more warnings.
>>>>>
>>>>> In such case, turning on -Werror temporarily would require
>>>>> switching on CONFIG_WERROR in the configuration, building,
>>>>> then switching off CONFIG_WERROR.
>>>>>
>>>>> For this use case, this patch introduces a new 'e' modifier
>>>>> to W= as a short hand for KCFLAGS+=-Werror" so that -Werror
>>>>> got added to the kernel (built-in) and modules' CFLAGS.
>>>>>
>>>>> Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
>>>>> ---
>>>>>  Makefile                   |  1 +
>>>>>  scripts/Makefile.extrawarn | 13 +++++++++++--
>>>>>  2 files changed, 12 insertions(+), 2 deletions(-)
>>>>>
>>>>> Changes since v0[0]:
>>>>>
>>>>>  - rebase on top of commit 64a91907c896 ("kbuild: refactor scripts/Makefile.extrawarn")
>>>>>  - document use case after commit 3fe617ccafd6 ("Enable '-Werror' by default for all kernel builds")
>>>>>
>>>>> [0] https://lore.kernel.org/all/1422803720-14723-1-git-send-email-ydroneaud@opteya.com/
>>>>
>>>>
>>>> I remembered the previous submission, I liked it, but I had lost it.
>>>>
>>>> It seems already 7 years ago, (before I became the Kbuild maintainer).
>>>> Thanks for coming back to this.
>>>>
>>>>
>>>> I like this, but I will wait some time for review comments.
>>>
>>> Dunno, this seems pretty simple:
>>>
>>> $ ./scripts/config -e WERROR
>>> $ make ... W=12
>>
>> Yeah, that's about what I was thinking too..
> 
> 
> 
> But, you cannot change the .config
> when you build external modules.
> 
> "make W=e" might be useful for people who strive to
> keep their downstream modules warning-free.
> 
> 
> W=e is the same pattern.
> I do not see much downside.
> 

Well, I don't see much downside either.

> 
> 
> (BTW, I do not like CONFIG_WERROR.)

Yeah, I disable it most of the time, but I am pretty good
at searching for errors & warnings. Apparently some people
are not.

-- 
~Randy