std::move_if_noexcept

// move_if_noexcept example
#include <utility>      // std::move_if_noexcept
#include <iostream>     // std::cout
// function with lvalue and rvalue reference overloads:
template <class T> void overloaded (T&  x) {std::cout << "[lvalue]\n";}
template <class T> void overloaded (T&& x) {std::cout << "[rvalue]\n";}
struct A {   // copyable + moveable (noexcept)
  A() noexcept {}
  A (const A&) noexcept {}
  A (A&&) noexcept {}
};
struct B {   // copyable + moveable (no noexcept)
  B() {}
  B (const B&) {}
  B (B&&) {}
};
struct C {   // moveable only (no noexcept)
  C() {}
  C (C&&) {}
};
int main () {
  std::cout << "A: "; overloaded (std::move_if_noexcept(A()));
  std::cout << "B: "; overloaded (std::move_if_noexcept(B()));
  std::cout << "C: "; overloaded (std::move_if_noexcept(C()));
  return 0;
}