alias this & cast

[andre via Digitalmars-d-learn]

Hi,

I am 80% sure, the failing assertion is correct but please have a 
look.
Second assertion fails.

Kind regards
André

class A{}

class B{}

class C : B
{
	A a;
	alias a this;
	
	this()
	{
		a = new A();
	}
}

void main()
{
	B b = new C();

	// OK
	assert(cast(C)b);
	
	// fails
	assert(cast(A)b);	
}