Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20220228103142.3301082-1-arnd@kernel.org> <YhyxML05rjJ/57Vk@FVFF77S0Q05N>
In-Reply-To: <YhyxML05rjJ/57Vk@FVFF77S0Q05N>
From:   Arnd Bergmann <arnd@kernel.org>
Date:   Mon, 28 Feb 2022 12:37:37 +0100
Message-ID: <CAK8P3a0CTmtUq+Uba2S3D7wjSstew2M+LfzZoOcKdKK9cfXO9A@mail.gmail.com>
Subject: Re: [PATCH] [v2] Kbuild: move to -std=gnu11
To:     Mark Rutland <mark.rutland@arm.com>
Cc:     Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Masahiro Yamada <masahiroy@kernel.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 <linux-arm-kernel@lists.infradead.org>,
        Intel Graphics <intel-gfx@lists.freedesktop.org>,
        dri-devel <dri-devel@lists.freedesktop.org>,
        greybus-dev@lists.linaro.org, linux-staging@lists.linux.dev,
        linux-btrfs <linux-btrfs@vger.kernel.org>,
        Marco Elver <elver@google.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Mon, Feb 28, 2022 at 12:25 PM Mark Rutland <mark.rutland@arm.com> wrote:
> On Mon, Feb 28, 2022 at 11:27:43AM +0100, Arnd Bergmann wrote:
> >
> > Nathan Chancellor reported an additional -Wdeclaration-after-statement
> > warning that appears in a system header on arm, this still needs a
> > workaround.
>
> FWIW, I had a go at moving to c99 a few weeks ago (to be able to use
> for-loop-declarations in some concurrency primitives), and when I tried, I also
> saw declaration-after-statement warnings when building modpost.c, which is easy
> enough to fix:
>
>   https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/commit/?h=treewide/gnu99&id=505775bd6fd0bc1883f3271f826963066bbdc194

I think the KBUILD_USERCFLAGS portion and the modpost.c fix for it
make sense regardless of the -std=gnu11 change, but your change
to KBUILD_CFLAGS is not actually needed because the warning is
already enabled there -- gnu89 allows intermingled declarations since
gcc-3.4, so the warning flag was added during early 2.6.x kernels.

       Arnd