#include <iostream>
using namespace std;
class Exercise 
{
public:
 int a;
    Exercise(){cout<<"constructor\n";}
 Exercise(const Exercise& x)
 {
  cout<<"copy constructor\n";
  a = x.a;
 }
 
 Exercise& operator= (Exercise &x)
 {
  a = x.a;
  cout<<"assignment operaor\n";
        return *this;
 }
};
Exercise fun(Exercise& );
int main(void)
{
 Exercise y;
 Exercise z;
 z = fun(y);
 return 0;
}
Exercise fun(Exercise& z)
{
 return z;
}

constructor.cpp: In function `int main()':
constructor.cpp:30: initialization of non-const reference type `class Exercise &
'
constructor.cpp:30: from rvalue of type `Exercise'
constructor.cpp:17: in passing argument 1 of `Exercise::operator =(Exercise &)'