how std::thread constructor detects rvalue reference?

Question

Obviously it is possible to pass an rvalue reference to std::thread constructor. My problem is with definition of this constructor in cppreference. It says that

Answer 1

It is common problem of the perfect forwarding. If you want to restore information about rvalue in the function, you have to use std::forward std::forward . If you are interested in the value type detection you may read this value_category . From the description you can find the information how the compiler recognizes rvalue, xvalue, lvalue, prvalue, gvalue on compile time.