linux-kernel - Re: [Cocci] coccinelle: bool if (foo) return true; else return false;

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Date:	Wed, 20 Apr 2016 00:25:34 -0700
From:	Joe Perches <joe@...ches.com>
To:	Michael Stefaniuc <mstefani@...hat.com>,
	Julia Lawall <julia.lawall@...6.fr>
Cc:	cocci <cocci@...teme.lip6.fr>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [Cocci] coccinelle: bool if (foo) return true; else return
 false;

On Wed, 2016-04-20 at 09:19 +0200, Michael Stefaniuc wrote:
> On 04/19/2016 09:15 PM, Julia Lawall wrote:
> > On Tue, 19 Apr 2016, Joe Perches wrote:
> > > There's ~150 of these in the kernel.
> > > 
> > > Maybe there's use for this conversion to be added
> > > to scripts/coccinelle/misc/boolreturn.cocci or in
> > > a separate file.
> > > 
> > > $ cat booltruefalse.cocci
> > > @@
> > > identifier fn;
> > > expression e;
> > > typedef bool;
> > > symbol true;
> > > symbol false;
> > > @@
> > > 
> > > bool fn ( ... )
> > > {
> > > <...
> > > -	if (e) return true; else return false;
> > > +	return e;
> Shouldn't that be:
>     return !!e
> ?

No, it's not necessary.
The compiler does that because the return type is bool

6.3.1.2 Boolean type

When any scalar value is converted to _Bool, the result is 0 if the value compares equal
to 0; otherwise, the result is 1.