From mboxrd@z Thu Jan  1 00:00:00 1970
From: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Subject: Re: [PATCH 1/2] Compiler Attributes: add support for __fallthrough
 (gcc >= 7.1)
Date: Mon, 22 Oct 2018 11:41:23 +0200
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To: Kees Cook <keescook@chromium.org>
Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com>, Ted Ts'o <tytso@mit.edu>, Greg KH <gregkh@linuxfoundation.org>, linux-kernel <linux-kernel@vger.kernel.org>, Dan <dan.carpenter@oracle.com>, Andreas Dilger <adilger.kernel@dilger.ca>, Masahiro Yamada <yamada.masahiro@socionext.com>, Michal Marek <michal.lkml@markovi.net>, Steven Rostedt <rostedt@goodmis.org>, Mauro Carvalho Chehab <mchehab+samsung@kernel.org>, Olof Johansson <olof@lxom.net>, Konstantin Ryabitsev <konstantin@linuxfoundation.org>, David Miller <davem@davemloft.net>, Andrey Ryabinin <aryabinin@virtuozzo.com>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@kernel.org>, Paul Lawrence <paullawrence@google.com>, Sandipan Das <sandipan@linux.vnet.ibm.com>, Andrey Konovalov <andreykn>
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On Mon, Oct 22, 2018 at 11:36 AM Kees Cook <keescook@chromium.org> wrote:
>
> We need to make sure the static analyzers are happy with either
> method. Additionally, when was -Wimplicit-fallthrough added to GCC? If
> it was added _before_ the attribute, we need to continue using the
> comment style otherwise we lose coverage even with gcc itself.
> Additionally, does Clang support this attribute (it supports
> -Wimplicit-fallthrough).

Please take a look at the rationale (also more details at the linked thread):

  * gcc 7.1 added -Wimplicit-fallthrough at the same time as the
attribute and the comment parsing.
  * clang does *not* support the attribute in C.

Cheers,
Miguel