Re: [Xen-devel] [PATCH 12/12] xen-blkfront: Avoid that gcc 7 warns about fall-through when building with W=1

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Fri, Aug 18, 2017 at 09:54:01AM +0100, Roger Pau Monn303251 wrote:
> On Thu, Aug 17, 2017 at 04:23:11PM -0700, Bart Van Assche wrote:
> > Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxx>
> > Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> > Cc: Roger Pau Monn303251 <roger.pau@xxxxxxxxxx>
> > Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
> > ---
> >  drivers/block/xen-blkfront.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
> > index 98e34e4c62b8..270019e3e5d8 100644
> > --- a/drivers/block/xen-blkfront.c
> > +++ b/drivers/block/xen-blkfront.c
> > @@ -2456,7 +2456,7 @@ static void blkback_changed(struct xenbus_device *dev,
> >     case XenbusStateClosed:
> >             if (dev->state == XenbusStateClosed)
> >                     break;
> > -           /* Missed the backend's Closing state -- fallthrough */
> > +           /* fall through */
> 
> This is losing information present in the original comment. Would
> splitting the comment into two make gcc happy?

What about:

-               /* Missed the backend's Closing state -- fallthrough */
+               /* fallthrough -- Missed the backend's Closing state */

FIY:
https://gcc.gnu.org/onlinedocs/gcc-7.2.0/gcc/Warning-Options.html#index-Wimplicit-fallthrough

A dash seems to be needed between "fall through" and a extra comment,
with fallthrough first.

Regards,

-- 
Anthony PERARD

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