How can I detect whether a type is a visible base of another type?

If I do

struct A{};
 struct C:private A{};
 
 typedef char (&yes)[1];
 typedef char (&no)[2];
 
 template <typename B, typename D>
 struct Host
 {
  operator B*() const;
  operator D*();
 };
 
 template <typename B, typename D>
 struct is_base_of
 {
 template <typename T> 
 static yes check(D*, T);
 static no check(B*, int);
 
 static const bool value = sizeof(check(Host<B,D>(), int())) == sizeof(yes);
 };
 
 int main(){
  std::cout<<is_base_of<A,C>::value<<std::endl;
 }
 

I get a 1. I would like to get a 0 when C is a private A, and a 1 when C is a public A

[the code is derived from How `is_base_of` works? ]

---