Perfect forwarding of this pointer?

Question

I have the following code:

template<typename T>
class Dispatcher
{
public:
    void operator()(T&& v) {}
};

struct S
{
    Dispatcher<S*> dispatcher;

    void test()
    {
        dispatcher(this);
    }
};

And it gives me an error error C2664: 'void Dispatcher<S *>::operator ()(T &&)' : cannot convert argument 1 from 'S *const ' to 'S *&&' in VisualStudio only. In gcc and clang it works ok.

I searched the documentation and the only thing I found here is: When used according to the following recipe in a function template, forwards the argument to another function with the value category it had when passed to the calling function.

Does that means perfect forwarding is guaranteed to work only with functions? Does gcc and clang are not following the standard?

Why are you linking to `std::forward` while your code does not contain it and you don' t really mention it? — Holt, Apr 19 '16 at 12:39
@Holt I removed all the code and left only the minimal example that actually fails. — nikitablack, Apr 19 '16 at 12:41
Still, you're not using forwarding. So how is the semantics of forwarding relevant? — Lightness Races in Orbit, Apr 19 '16 at 12:43
Compiles fine on GCC: http://coliru.stacked-crooked.com/a/653cdea8e03919d8 — David Haim, Apr 19 '16 at 12:45
@LightnessRacesinOrbit I thought if I'm using template argument together with `&&` it uses collapsing rules which are only useful with perfect forwarding. — nikitablack, Apr 19 '16 at 12:46
@nikitablack Here `T` is a parameter of `Dispatcher`, not of its `operator()`. `T&&` is not a forwarding reference because `T` is not deduded. — Quentin, Apr 19 '16 at 12:54
@Quentin Just to be clear - reference collapsing rules work **only with templated function**, right? — nikitablack, Apr 19 '16 at 13:03

Perfect forwarding of this pointer?

0 Answers0