5. a) Why doesn't this code compile? b) What needs to be amended and / or supplemented in the code to compile the code? What is the solution most effective? c) Why is this change necessary when using std :: vector? (C++)

1 #include 2 #include 3 #include 45 class Token { 6 private: 7 std::unique_ptr > ptr = std::make_unique >(); 8 public: 9 Token() = default; 10 Token(Token& t0) noexcept { std::cout << "Token(Token&)"; } 11 }; 12 13 int main() { 14 std::vector v; 15 16 for(int i = 0; i<10; ++i) { 17 v.emplace_back(); 18 } 19 20 return 0; 21 }