#include <iostream>
    struct myBigObject
    {
      size_t x;
      myBigObject() : x() {}
      myBigObject(const myBigObject &other)
      {
        std::cout << "Copy myBigObject" << std::endl;
        x = 12;
      }
    };

    struct MyClass
    {
        MyClass(myBigObject s)
          : s_(s) 
        { 
          std::cout << "x of s : " << s.x << std::endl;
          std::cout << "x of s_ : " << s_.x << std::endl;
        }
        myBigObject s_;
    };

    int main()
    {
      std::cout << "A:" << std::endl;
      MyClass x{ myBigObject() };
      std::cout << "B:" << std::endl;
      myBigObject y;
      MyClass z{ y };
    }