Virtual Function Optimization

[Ben Phillips]

How much does D optimize virtual function calls? Lets say you have the following
interface and class (not very useful ones).

interface Collection
{
public int size();
}

class Array : Collection
{
private int[] array;
public:
this() { array.length = 10; }
int size() { return array.length; }
}

Now consider the following statements

Collection c = new Array();
Array a = new Array();

c.size(); // clearly a virtual function call
a.size(); // ?????

Can the compiler deduce that "a.size()" should not be called through the vtable
since the type of "a" is not ambiguous?