Re: [Xen-devel] [PATCH 14 of 18] tools/libvchan: fix build errors caused by Werror in io.c

[Olaf Hering <olaf@xxxxxxxxx>]

On Tue, Apr 03, Ian Campbell wrote:

> On Tue, 2012-04-03 at 11:25 +0100, Ian Jackson wrote:
> > Olaf Hering writes ("[PATCH 14 of 18] tools/libvchan: fix build errors 
> > caused by Werror in io.c"):
> > > tools/libvchan: fix build errors caused by Werror in io.c
> > ...
> > > io.c:196: warning: ignoring return value of 'writev', declared with 
> > > attribute warn_unused_result
> > ...
> > > -         writev(-1, iov, 2);
> > > +         /* Silence gcc warning, will always fail */
> > > +         if (writev(-1, iov, 2));
> > 
> > I still think this is an unpleasant idiom.  Does casting the result to
> > void not help ?

Just '(void)writev(...);' does not prevent the warning.

> What does writev(-1,...) even mean? Can we not just nuke it?

Its just there for debugging with strace. Wether the whole debug ca be
removed, no idea.

Olaf

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