Re: [PATCH 1/2] Compiler Attributes: add support for __fallthrough (gcc >= 7.1)

From: Kees Cook
Date: Mon Oct 22 2018 - 06:53:20 EST


On Mon, Oct 22, 2018 at 2:41 AM, Miguel Ojeda
<miguel.ojeda.sandonis@xxxxxxxxx> wrote:
> On Mon, Oct 22, 2018 at 11:36 AM Kees Cook <keescook@xxxxxxxxxxxx> 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