linux-kernel - Re: [PATCH 10/20] input: mouse: synaptics: Place braces around empty if() body

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Message-ID: <20201106074020.GT4488@dell>
Date:   Fri, 6 Nov 2020 07:40:20 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     joe@...ches.com, linux-kernel@...r.kernel.org,
        Henrik Rydberg <rydberg@...math.org>,
        Peter Osterlund <petero2@...ia.com>,
        Stefan Gmeiner <riddlebox@...esurf.ch>,
        "C. Scott Ananian" <cananian@...mni.priceton.edu>,
        Bruce Kalk <kall@...pass.com>,
        this to <linux-input@...r.kernel.org>
Subject: Re: [PATCH 10/20] input: mouse: synaptics: Place braces around empty
 if() body

On Thu, 05 Nov 2020, Dmitry Torokhov wrote:

> Hi Lee,
> 
> On Wed, Nov 04, 2020 at 04:24:17PM +0000, Lee Jones wrote:
> > Fixes the following W=1 kernel build warning(s):
> > 
> >  drivers/input/mouse/synaptics.c: In function ‘synaptics_process_packet’:
> >  drivers/input/mouse/synaptics.c:1110:6: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
> > 
> > Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>
> > Cc: Henrik Rydberg <rydberg@...math.org>
> > Cc: Peter Osterlund <petero2@...ia.com>
> > Cc: Stefan Gmeiner <riddlebox@...esurf.ch>
> > Cc: "C. Scott Ananian" <cananian@...mni.priceton.edu>
> > Cc: Bruce Kalk <kall@...pass.com>
> > Cc: this to <linux-input@...r.kernel.org>
> > Cc: linux-input@...r.kernel.org
> > Signed-off-by: Lee Jones <lee.jones@...aro.org>
> > ---
> >  drivers/input/mouse/synaptics.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptics.c
> > index 82577095e175e..07835939d83b9 100644
> > --- a/drivers/input/mouse/synaptics.c
> > +++ b/drivers/input/mouse/synaptics.c
> > @@ -1106,8 +1106,9 @@ static void synaptics_process_packet(struct psmouse *psmouse)
> >  					num_fingers = hw.w + 2;
> >  				break;
> >  			case 2:
> > -				if (SYN_MODEL_PEN(info->model_id))
> > +				if (SYN_MODEL_PEN(info->model_id)) {
> >  					;   /* Nothing, treat a pen as a single finger */
> > +				}
> 
> This gives me:
> 
> WARNING: braces {} are not necessary for single statement blocks
> 
> from checkpatch.

Yes, because checkpatch just sees it as a normal single statement,
rather than an empty one.  It complains about macros that can be
compiled out too, which is even more dangerous.

GCC wins this one though, as it *knows* it's an empty statement.

-- 
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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