#include <iostream>
 
struct A { };
struct B : public A { typedef A Base; };
struct C : public B {};
 
template<typename T>
struct to_void
{
	typedef void type;
};
 
template <typename T, typename dummy = void>
struct has_base_typedef : std::false_type {};
 
template <typename T>
struct has_base_typedef<T, typename to_void<typename T::Base>::type> : std::true_type {};
 
int main()
{
	std::cout << has_base_typedef<A>::value;
	std::cout << has_base_typedef<B>::value;
	std::cout << has_base_typedef<C>::value;
}

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