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#include <stdio.h>
#include <type_traits>
struct B {
virtual int foo() {
puts("B");
};
template<typename X>
using baseFooType = typename std::enable_if<X::override_foo,decltype(((B*)nullptr)->foo())>::type;
};
struct C : public B {
constexpr static bool override_foo = true;
};
struct D : public B {
constexpr static bool override_foo = true;
};
struct E : public C {
baseFooType<C> foo() override {
puts("E");
}
};
struct F : public D {
baseFooType<D> foo() override {
puts("F");
}
};
int main()
{
E().foo();
F().foo();
}
