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References: <1422803720-14723-1-git-send-email-ydroneaud@opteya.com> <20220408084607.106468-1-ydroneaud@opteya.com>
In-Reply-To: <20220408084607.106468-1-ydroneaud@opteya.com>
From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Fri, 8 Apr 2022 20:05:20 +0900
Message-ID: <CAK7LNAQZLt_OecOogOQiSu5snW+sffsMoFgVcjPTx_idj_=_tQ@mail.gmail.com>
Subject: Re: [PATCHv1] kbuild: support W=e to make build abort in case of warning
To:     Yann Droneaud <ydroneaud@opteya.com>
Cc:     Michal Marek <michal.lkml@markovi.net>,
        Nick Desaulniers <ndesaulniers@google.com>,
        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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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.


> diff --git a/Makefile b/Makefile
> index 8c7de9a72ea2..6dc621af18d1 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1649,6 +1649,7 @@ help:
>         @echo  '                1: warnings which may be relevant and do not occur too often'
>         @echo  '                2: warnings which occur quite often but may still be relevant'
>         @echo  '                3: more obscure warnings, can most likely be ignored'
> +       @echo  '                e: warnings are being treated as errors'
>         @echo  '                Multiple levels can be combined with W=12 or W=123'
>         @echo  ''
>         @echo  'Execute "make" or "make all" to build all targets marked with [*] '
> diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
> index 650d0b8ceec3..f5f0d6f09053 100644
> --- a/scripts/Makefile.extrawarn
> +++ b/scripts/Makefile.extrawarn
> @@ -2,8 +2,8 @@
>  # ==========================================================================
>  # make W=... settings
>  #
> -# There are three warning groups enabled by W=1, W=2, W=3.
> -# They are independent, and can be combined like W=12 or W=123.
> +# There are four warning groups enabled by W=1, W=2, W=3, and W=e
> +# They are independent, and can be combined like W=12 or W=123e.
>  # ==========================================================================
>
>  KBUILD_CFLAGS += $(call cc-disable-warning, packed-not-aligned)
> @@ -94,3 +94,12 @@ KBUILD_CFLAGS += $(call cc-option, -Wpacked-bitfield-compat)
>  KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN3
>
>  endif
> +
> +#
> +# W=e - error out on warnings
> +#
> +ifneq ($(findstring e, $(KBUILD_EXTRA_WARN)),)
> +
> +KBUILD_CFLAGS += -Werror
> +
> +endif
> --
> 2.32.0
>


--
Best Regards
Masahiro Yamada