Re: [OB PATCH] Avoid testcase build failures with -Wunused-value

[Gary Benson <gbenson@redhat.com>]

Pedro Alves wrote:
> On 6/23/20 12:26 PM, Gary Benson via Gdb-patches wrote:
> > --- a/gdb/testsuite/gdb.cp/namespace.cc
> > +++ b/gdb/testsuite/gdb.cp/namespace.cc
> > @@ -150,22 +150,22 @@ namespace C
> >        // plan to have GDB try to print out, just to make sure that the
> >        // compiler and I agree which ones should be legal!  It's easy
> >        // to screw up when testing the boundaries of namespace stuff.
> > -      c;
> > +      int unused1 = c;
> 
> It looks like such a fix will only work until the compiler decides
> to enable -Wunused-variable by default too:
> 
> testsuite/gdb.cp/namespace.cc:153:11: warning: unused variable 'unused' [-Wunused-variable]
>       int unused = c;
>           ^
> 
> Try compiling the testcase with -Wall, with both g++ and clang++:
> 
>  $ clang++ testsuite/gdb.cp/namespace.cc -Wall
> 
> I think we should fix this with the more usual cast-to-void way:
> 
>  (void) c;

Ok, but, out of interest, what stops the compiler ignoring that?

Thanks,
Gary