implimenting interface function by inheriting from other class

[Alexey]

On Saturday, 21 August 2021 at 20:35:43 UTC, Alexey wrote:
> Hello
> ```D
> interface Int
> {
>     void coolFunc();
> }
>
> class C1
> {
>     void coolFunc()
>     {
>         return;
>     }
> }
>
> class C2 : C1, Int
> {
>
> }
>
> void main()
> {
>     auto c = new C2;
> }
> ```
> dmd says it's not Ok:
> t.d(14): Error: class `t.C2` interface function `void 
> coolFunc()` is not implemented
>
> how to make dmd happy?

so, Is this a bug in dmd or not?