Problem of override

[Eric Suen]

Why these code is valid:

class A {
  public char[] test() {
    return "A";
  }
}

class B : A {
}

class C : B {
  public char[] test() {
    return super.test() ~ " C";
  }
}

But these are not?

class A {
  public char[] test() {
    return "A";
  }
}

class B : A {
  public void test(char[] a) {
  }
}

class C : B {
  public char[] test() {
    return super.test() ~ " C";
  }
}