An argument to this function will bind to an rvalue reference:
void f(int && i);
template <typename T>
void f(T && t);
Do they mean the same thing?
Universal reference was a term Scott Meyers coined to describe the concept of taking an rvalue reference to a cv-unqualified template parameter, which can then be deduced as either a value or an lvalue reference.
At the time the C++ standard didn't have a special term for this, which was an oversight in C++11 and makes it hard to teach. This oversight was remedied by N4164, which added the following definition to [temp.deduct]:
A forwarding reference is an rvalue reference to a cv-unqualified template parameter. If
Pis a forwarding reference and the argument is an lvalue, the type “lvalue reference to A” is used in place of A for type deduction.
Hence, the two mean the same thing, and the current C++ standard term is forwarding reference. The paper itself articulates why "forwarding reference" is a better term than "universal reference."
Is it only a forwarding reference if the function body calls
Nope, what you do with a forwarding reference is irrelevant to the name. The concept forwarding reference simply refers to how the type
T is deduced in:
template <class T> void foo(T&& ); // <==
It does not need to be subsequently forwarded .