class {
public:
  template<typename T>             // convertible to any type
    operator T*() const            // of null non-member pointer...
    { return 0; }
  template<typename C, typename T> // or any type of null
    operator T C::*() const        // member pointer...
    { return 0; }
private:
  void operator&() const;    // whose address can't be taken
} nullptr = {};              // and whose name is nullptr