Test case:

class A
{
	class B
	{
		void bar()
		{
			return foo!(int)();
		}
	}
	
	int foo(T)()
	{
		return 42;
	}
	
	
	this()
	{
		b = new B();
	}
	
	B b;
}

void main()
{
	A a = new A();
	a.b.bar();
}

I think the problem is that prior to calling A.foo!(int) it tries to execute an A.invariant(), but `this' pointer is null for some reason.