1 namespace std { 2 template<typename> struct mersenne_twister_engine { 3 friend bool operator==(const mersenne_twister_engine &, 4 const mersenne_twister_engine &) { 5 return false; 6 } 7 }; 8 struct random_device { 9 mersenne_twister_engine<int> mt; // require complete type 10 }; 11 } 12 13