4. a) Why is the destructor called 3 times? b) On which row will the Token object be created, which will disappear first? c) Why does this object disappear before the other two objects? d) Why is the default constructor called only once?

1 #include 2 #include 34 class Token { 5 public: 6 Token() { std::cout << "Token()"; } 7 ~Token() { std::cout << "~Token()"; } 8 }; 9 10 template 11 std::unique_ptr foo(T t0) { 12 return std::unique_ptr(new T(t0)); 13 }; 14 15 int main() { 16 Token&& t = Token(); 17 18 auto ptr = foo(t); 19 20 return 0; 21 }