#include <iostream>
 
class B //a move only type
{
    B( const B& )=delete;
    B& operator=( const B& ) = delete;
public:
    B( B&& )
    {
        std::cout << "B&&\n";
    }
 
    B& operator=( B&& )
    {
        std::cout << "B=\n";
            return *this; 
    }
    B(){ std::cout << "B()\n"; }
};
 
struct error  //the other parts are stripped of for simplicity.
{
    B get()
    {
        return std::move(b);
    }
private :
    B b{};// B is a move only type.
};
 
int main()
{
  error er{};
  er.get();
}

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