isCovariantWith

1 interface I { I clone(); }
2 interface J { J clone(); }
3 class C : I
4 {
5     override C clone()   // covariant overriding of I.clone()
6     {
7         return new C;
8     }
9 }
10 
11 // C.clone() can override I.clone(), indeed.
12 static assert(isCovariantWith!(typeof(C.clone), typeof(I.clone)));
13 
14 // C.clone() can't override J.clone(); the return type C is not implicitly
15 // convertible to J.
16 static assert(!isCovariantWith!(typeof(C.clone), typeof(J.clone)));