fake forwarding reference

• StackOverflow - Are there any use cases for std::forward with a prvalue?
• StackOverflow - How does std::forward receive the correct argument?
• N2951 forward

C++17(N4659) [temp.deduct.call]/p3

[...] A forwarding reference is an rvalue reference to a cv-unqualified template parameter that does not represent a template parameter of a class template (during class template argument deduction ([over.match.class.deduct])). If P is a forwarding reference and the argument is an lvalue, the type "lvalue reference to A" is used in place of A for type deduction. [...]