[rtems commit] semopen.c: Address set but unused variable warning

[Pavel Pisa]

Hello Ralf and others,

On Sunday 22 of September 2013 05:01:49 Ralf Corsepius wrote:
> > diff --git a/cpukit/posix/src/semopen.c b/cpukit/posix/src/semopen.c
> > index b863080..e61fad0 100644
> > --- a/cpukit/posix/src/semopen.c
> > +++ b/cpukit/posix/src/semopen.c
> > @@ -43,6 +43,14 @@
> >    *        parameters must be present.
> >    */
> >
> > +/*
> > + * mode is set but never used. GCC gives a warning for this
> > + * and we need to tell GCC not to complain. But we have to
> > + * have it because we have to work through the variable
> > + * arguments to get to attr.
> > + */
> > +#pragma GCC diagnostic push
> > +#pragma GCC diagnostic ignored "-Wunused-but-set-variable"
> >   sem_t *sem_open(
> >     const char *name,
> >     int         oflag,
> > @@ -137,3 +145,4 @@ return_id:
> >       return (sem_t *)&the_semaphore->Object.id;
> >     #endif
> >   }
> > +#pragma GCC diagnostic pop
>
> Why this brutal and probably non-portable way to suppress warnings?
>
> Why doesn't __attribute__((unused)) or similar suffice?

I would prefer to see something like RTEMS_ATTR_UNUSED to support
multiple compilers. You can look at my collection of these in
uLUt definitions file

http://sourceforge.net/p/ulan/ulut/ci/master/tree/ulut/ul_utdefs.h

I declare file contents (by this e-mail) as free for public
domain use (uLUt as whole is is GPL/LGPL/MPL RTEMS compatible too).

As for the actual __attribute__((unused)) there is even portable
solution which does not depend on GCC extension.

{
  int my_unused_var;
  (void) my_unused_var;
}

This solution should be accepted by all compilers and is suggested
by some people as better option.

Best wishes,

             Pavel