struct opEquals does not work with parameter of same type - bug or feature?

[Sean Eskapp]

== Quote from Jonathan M Davis (jmdavisProg at gmx.com)'s article
> On Monday, August 29, 2011 22:41:26 Sean Eskapp wrote:
> > I am trying to build a struct with equality testing, using this code:
> >
> > struct Foo
> > {
> >     const bool opEquals(Foo f)
> >     {
> >         return true;
> >     }
> > }
> >
> > This gives me the error that the parameter should be of type "ref const
> > Foo". Fine.
> >
> > struct Foo
> > {
> >     const bool opEquals(ref const Foo f)
> >     {
> >         return true;
> >     }
> > }
> >
> > This, however, does not work with code like:
> >
> > Foo bar()
> > {
> >     return Foo();
> > }
> >
> > assert(Foo() == bar());
> >
> > "function Foo.opEquals(ref const const(Foo) f) const is not callable using
> > argument types (Foo)" and "bar() is not an lvalue".
> >
> > How can I do this?
> http://d.puremagic.com/issues/show_bug.cgi?id=3659
> http://stackoverflow.com/questions/6986175/const-ref-and-rvalue-in-d
> - Jonathan M Davis

Ah, thanks!