gc.cpp

struct real_gc_base {
	virtual ~real_gc_base() {}
};

struct gc : virtual real_gc_base {
};

struct b1 : gc {
};

struct b2 : b1 {
};

struct b3 : b1 {
};

struct d : b2, b3 {
};

union pointer {
	struct {
		size_t p            : 40;
		size_t typed_offset : 24;
	};
};

struct raw_reference {
	real_gc_base* get_base() {
		return reinterpret_cast<real_gc_base*>(ptr.p);
	}

	pointer ptr;
};

template<typename T>
struct reference : raw_reference {
	T* operator->() {
		return reinterpret_cast<T*>(ptr.p + (ptr.typed_offset * sizeof(void*)));
	}
};

struct raw_reference_preferred {
	real_gc_base* get_base() {
		return dynamic_cast<real_gc_base*>(ptr);
	}

	void* ptr;
};

template<typename T>
struct reference_preferred : raw_reference_preferred {
	T* operator->() {
		return static_cast<T*>(ptr);
	}
};