linux-kernel - Re: Possible code defects: macros and precedence

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Message-ID: <1474391253.1954.39.camel@perches.com>
Date:   Tue, 20 Sep 2016 10:07:33 -0700
From:   Joe Perches <joe@...ches.com>
To:     Julia Lawall <julia.lawall@...6.fr>
Cc:     Dan Carpenter <error27@...il.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: Possible code defects: macros and precedence

On Tue, 2016-09-20 at 15:14 +0200, Julia Lawall wrote:
> The semantic patch below finds a binary operator in a macro and a binary
> operator in the use of the macro, and checks if the priority of the
> operator in the macro is higher (lower number) than the priority of the
> operator in the use.  If this is the case, it adds parentheses in the use,
> which is not what one wants, but serves to show where the problem is

Thanks, this works on the trivial example I suggested
without an #include

I've tried it on trivial files with --recursive-includes
and it seems to work there too.

I'll investigate some more convoluted uses later.

btw: There are ~15K checkpatch MACRO_ARG_PRECEDENCE
messages in the -next kernel tree.  That's probably
too many for a theoretical and likely not an actual
problem.

cheers, Joe