struct sfinae_one { char a[1]; };
struct sfinae_two { char a[2]; };
 
const char* get_value_description(int is_glvalue, int is_rvalue)
{
    if (is_glvalue == sizeof (sfinae_one)) return "prvalue";
    if (is_rvalue == sizeof (sfinae_one)) return "lvalue";
    return "xvalue";
}
 
template<typename T>
sfinae_one SFINAE_test_1( const T& t );
template<typename T>
sfinae_two SFINAE_test_1( T& t );
 
template<typename T>
sfinae_one SFINAE_test_2( const T& t );
template<typename T>
sfinae_two SFINAE_test_2( T&& t );
 
#define VALUE_CAT(expr) get_value_description(sizeof SFINAE_test_1((expr)), sizeof SFINAE_test_2((expr)))
 
#include <iostream>
using namespace std;
int main()
{
    int x;
 
    cout << VALUE_CAT(x) << endl; // prints lvalue
    cout << VALUE_CAT(move(x)) << endl; // prints xvalue
    cout << VALUE_CAT(42) << endl; // prints prvalue
}

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