Swift version 4.1 (swift-4.1-RELEASE)/usercode/main.swift:17:8: error: type 'FooBImpl<P>' does not conform to protocol 'Foo' struct FooBImpl<P>: FooB { ^ /usercode/main.swift:2:20: note: protocol requires nested type 'Bar'; do you want to add it? associatedtype Bar ^ /usercode/main.swift:17:8: error: type 'FooBImpl<P>' does not conform to protocol 'FooB' struct FooBImpl<P>: FooB { ^