fork(3) download

copy

#include <iostream>
#include <type_traits>
using namespace std;
 
template <typename T>
struct dummy {};
 
template <typename T, typename U>
struct fail : dummy<T>, dummy<U>, true_type {};
 
template <typename T, typename U = void>
struct test : false_type {};
 
template <typename T>
struct test<T, typename enable_if<fail<T, T>::value, void>::type> : true_type {};
 
int main() {
	cout << test<int>::value << endl;
}

prog.cpp: In instantiation of ‘struct fail<int, int>’:
prog.cpp:18:19:   required from here
prog.cpp:9:8: error: duplicate base type ‘dummy<int>’ invalid
 struct fail : dummy<T>, dummy<U>, true_type {};
        ^

Standard output is empty