[splinterofchaos]

I did not mean "any rvalue-reference" and bind to "any l- or rvalue", but that you can have an "int &&", "int& &&", "const int& &&", and even "int&& &&". I updated my comment to say "can be made from" instead "can bind to".

Your code example does not work because you call "foo" instead of "bar". But consider this one:

#include <iostream>

using namespace std;

template<class T> T bar(T&& i){ return std::forward<T>(i); }

int main() {

  int i=0;

  cout << bar<int&&>(6) << endl;

  return 0;

}

[monk_the_dog]

Maybe you're confusing reference collapsing with universal references?

In your example, replace bar<int&&>(6) to bar<int&&>(i).

It won't compile because i is not an r value. bar(i) will compile, because the template parameter is a universal reverence that will become an lvalue (not an rvalue) through reference collapsing.

[splinterofchaos]

I called "bar" with "<int&&>" to demonstrate that you can bind an rvalue-ref to an rvalue-ref, not to suggest that's how it should be called.