module test;

class A
{
	int foo() { return 0; }
	
	int callfoo()
	{
		return foo();
	}
}

class B : A
{
	override int foo() { return 1; }
}

int test()
{
	A a = new B;
	return a.callfoo();
}

static assert(test() == 1);


Compiling with "dmd -c test.d" yields:
test.d(24): Error: static assert  (0 == 1) is false

If you use "a.foo()" instead of "a.callfoo()", the assert succeeds.