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#include <iostream>
 
struct A
{
  void WhoAmI() &&
  {
  	std::cout << "I am rvalue reference\n";
  }
 
  void WhoAmI() const &&
  {
  	std::cout << "I am const rvalue reference\n";
  }
 
};
 
 
A operator+(A a1, A a2)
{
  return {};
}
 
int main()
{
  A a;
//  a.WhoAmI(); // error
 
  A& ra = a;
  ra.WhoAmI(); // error
 
  (a + a).WhoAmI(); // ok
 
  return 0;
}
 

prog.cpp: In function ‘int main()’:
prog.cpp:29:13: error: passing ‘A’ as ‘this’ argument discards qualifiers [-fpermissive]
   ra.WhoAmI(); // error
             ^
prog.cpp:5:8: note:   in call to ‘void A::WhoAmI() &&’
   void WhoAmI() &&
        ^~~~~~

Standard output is empty