Type trait: Check if class have specific function (maybe inherit)

Question

I know that there are many possible ways to detect if a class has a specific function but non of them really work for my exact case. My current implementation to check for t

Answer 1

Here is a solution with or

#include 
#include 

struct A {
  auto foo() { return 0; }
};
struct B {
  auto bar() { return 0.0; }
};
struct C : public A {
  auto bAr() { return 0.0; }
};
struct D : public C {
  auto baR() { return 0.0; }
};

template 
using HasFoo_t = decltype(std::declval().foo());

int main() {
  std::cout << std::experimental::is_detected_v << std::endl;
  std::cout << std::experimental::is_detected_v << std::endl;
  std::cout << std::experimental::is_detected_v << std::endl;
  std::cout << std::experimental::is_detected_v << std::endl;
}