Bug 22232 – implementing interface function by inheriting from other class

asked at Discord and at Forum, but nobody could tell if this is a bug: ```D interface Int { void coolFunc(); } class C1 { void coolFunc() { return; } } class C2 : C1, Int { } void main() { auto c = new C2; } ``` dmd ends with error: t.d(14): Error: class t.C2 interface function void coolFunc() is not implemented

This is by design, see item 13 here: https://dlang.org/spec/interface.html Even if the parent already did the interface, the spec says the interface must be implemented again. You can do it by using forwarding functions.