Implicitly-declared move constructor
If no user-defined move constructors are provided for a class type (struct, class, or union), and all of the following is true:
- there are no user-declared copy constructors;
- there are no user-declared copy assignment operators;
- there are no user-declared move assignment operators;
- there is no user-declared destructor.
then the compiler will declare a move constructor as a non-explicit inline public member of its class with the signature T::T(T&&).