@swiftbot --version latest
protocol P1 { associatedtype Input } extension P1 { typealias InputP1 = Input } protocol P2 { associatedtype Input } extension P2 { typealias InputP2 = Input } struct Box<T> {} extension Box: P1 where T: P1 { typealias InputP1 = T.InputP1 } extension Box: P2 where T: P2 { typealias Input = T.InputP2 } func inputTypeP2<T>(_ type: T.Type) -> T.Input.Type where T: P2 { return T.Input.self } func inputTypeP1<T>(_ type: T.Type) -> T.Input.Type where T: P1 { return T.Input.self } struct A: P2, P1 { typealias Input = Int } print(inputTypeP1(Box<A>.self)) // セグフォ print(inputTypeP2(Box<A>.self))