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Date:   Mon, 22 Oct 2018 13:27:43 +0300
From:   Dan Carpenter <dan.carpenter@oracle.com>
To:     Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc:     "Theodore Y. Ts'o" <tytso@mit.edu>,
        Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
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        Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
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        Konstantin Ryabitsev <konstantin@linuxfoundation.org>,
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Subject: Re: [PATCH 1/2] Compiler Attributes: add support for __fallthrough
 (gcc >= 7.1)
Message-ID: <20181022102743.nua5fgbscyeymzal@mwanda>
References: <20181021171414.22674-1-miguel.ojeda.sandonis@gmail.com>
 <20181021171414.22674-2-miguel.ojeda.sandonis@gmail.com>
 <20181021222712.GI1617@thunk.org>
 <8fb78062-b6d4-6f2d-d943-44bec6b95ff0@petrovitsch.priv.at>
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On Mon, Oct 22, 2018 at 11:41:56AM +0200, Bernd Petrovitsch wrote:
> On 22/10/2018 00:27, Theodore Y. Ts'o wrote:
> > On Sun, Oct 21, 2018 at 07:14:13PM +0200, Miguel Ojeda wrote:
> >> From the GCC manual:
> >>
> >>   fallthrough
> >>
> >>     The fallthrough attribute with a null statement serves as a
> >>     fallthrough statement. It hints to the compiler that a statement
> >>     that falls through to another case label, or user-defined label
> >>     in a switch statement is intentional and thus the -Wimplicit-fallthrough
> >>     warning must not trigger. The fallthrough attribute may appear
> >>     at most once in each attribute list, and may not be mixed with
> >>     other attributes. It can only be used in a switch statement
> >>     (the compiler will issue an error otherwise), after a preceding
> >>     statement and before a logically succeeding case label,
> >>     or user-defined label.
> >>
> >>   https://gcc.gnu.org/onlinedocs/gcc/Statement-Attributes.html
> > 
> > Do we know if coverity understands the fallthrough attribute?  One of
> > the reasons why I started using /* fallthrough */ is because it kept
> > Coverity happy.
> 
> FWIW, current "eclipse" has the same "problem".
> 
> > If the conversion from /* fallthrough */ to the __fallthrough__
> > attribute means that we start gethting a lot of Coverity warnings,
> 
> We could keep both.

What does that even mean?  Use both the attribute and the comment until
Eclipse is updated?

	case 3:
		frob();
		__fall_through; /* fall through */
	case 4:

That seems like a wrong idea...

regards,
dan carpenter