Overloading const member function

[Nub Public]

Why doesn't overloading of const member functions work?

struct S {
	int a, b;
	
	int A() const { return a; }
	ref int A() { return a; }
	
	int min() const { return A() < b ? A() : b; }
}

DMD2 compiler error: S.A () is not callable using argument types () const

Is it a bug or by design?