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From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Tue, 1 Mar 2022 02:02:53 +0900
Message-ID: <CAK7LNATVs-yRX4PnURkLv3fz3gAnuzG2GxZ2gdvmJX2g+0P-_w@mail.gmail.com>
Subject: Re: [PATCH] [v2] Kbuild: move to -std=gnu11
To:     Arnd Bergmann <arnd@kernel.org>
Cc:     Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        llvm@lists.linux.dev, Jonathan Corbet <corbet@lwn.net>,
        Federico Vaga <federico.vaga@vaga.pv.it>,
        Alex Shi <alexs@kernel.org>, Hu Haowen <src.res@email.cn>,
        Michal Marek <michal.lkml@markovi.net>,
        Nick Desaulniers <ndesaulniers@google.com>,
        "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-doc-tw-discuss@lists.sourceforge.net,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        intel-gfx <intel-gfx@lists.freedesktop.org>,
        dri-devel <dri-devel@lists.freedesktop.org>,
        greybus-dev@lists.linaro.org, linux-staging@lists.linux.dev,
        linux-btrfs@vger.kernel.org
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On Mon, Feb 28, 2022 at 7:32 PM Arnd Bergmann <arnd@kernel.org> wrote:
>
> From: Arnd Bergmann <arnd@arndb.de>
>
> During a patch discussion, Linus brought up the option of changing
> the C standard version from gnu89 to gnu99, which allows using variable
> declaration inside of a for() loop. While the C99, C11 and later standards
> introduce many other features, most of these are already available in
> gnu89 as GNU extensions as well.
>
> An earlier attempt to do this when gcc-5 started defaulting to
> -std=gnu11 failed because at the time that caused warnings about
> designated initializers with older compilers. Now that gcc-5.1 is the
> minimum compiler version used for building kernels, that is no longer a
> concern. Similarly, the behavior of 'inline' functions changes between
> gnu89 and gnu11, but this was taken care of by defining 'inline' to
> include __attribute__((gnu_inline)) in order to allow building with
> clang a while ago.
>
> One minor issue that remains is an added gcc warning for shifts of
> negative integers when building with -Werror, which happens with the

Is this a typo?

   building with -Werror, ...
->
   building with -Wextra, ...


> 'make W=1' option, as well as for three drivers in the kernel that always
> enable -Werror, but it was only observed with the i915 driver so far.

Same here.

   enable -Werror, but ...
->
  enable -Wextra, but ...


Otherwise,

Acked-by: Masahiro Yamada <masahiroy@kernel.org>


Please let me know if you want me to pick up this.


--
Best Regards

Masahiro Yamada