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From: Kees Cook <keescook@chromium.org>
Date: Mon, 22 Oct 2018 03:53:12 -0700
Message-ID: <CAGXu5jLzfuEnWpJFL1Caq94nKbPps-QTaYGpge2CfZWj1Zzf9g@mail.gmail.com>
Subject: Re: [PATCH 1/2] Compiler Attributes: add support for __fallthrough
 (gcc >= 7.1)
To: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com>,
        "Ted Ts'o" <tytso@mit.edu>, Greg KH <gregkh@linuxfoundation.org>,
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Sender: linux-ext4-owner@vger.kernel.org

On Mon, Oct 22, 2018 at 2:41 AM, Miguel Ojeda
<miguel.ojeda.sandonis@gmail.com> wrote:
> 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.

Ah, perfect. I missed this. :)

>   * clang does *not* support the attribute in C.

Well that's not good. :)

-Kees

-- 
Kees Cook
Pixel Security