class MA
{
}
class MB : MA
{
}
class MC : MB
{
}
class A
{
MA foo() { return null; }
}
interface I
{
MB foo();
}
class B : A
{
override MC foo() { return null; }
}
class C : B, I
{
override MC foo() { return null; }
}
void main()
{
}
----
Error: function test.C.foo incompatible covariant types MA() and MB()