On Sun, Sep 13, 2015 at 02:50:53PM +0200, Manuel López-Ibáñez wrote:
> On 13/09/15 13:40, Mark Wielaard wrote:
> >Slightly adjusted patch attached. Now it is explicit that the warning is
> >enabled by -Wunused-variable for C, but not C++. There are testcases for
> >both C and C++ to check the defaults. And the hardcoded override is
> >removed for C++, so the user could enable it if they want.
> 
> >+  /* -Wunused-variable implies -Wunused-const-variable for C, but not
> >+     for C++, because const variables take the place of #defines in C++.  */
> >+  if (warn_unused_const_variable_set == -1)
> >+    warn_unused_const_variable_set = (warn_unused_variable
> >+				      && ! c_dialect_cxx ());
> >+
> 
> Can't you use LangEnabledBy() in c.opt to implement this?

Yes, I can. See simplified patch attached.
I wasn't aware there was already such a nice framework for this.

Thanks,

Mark