exit status: 1 with stderr:
<stdin>:15:1: error: type 'B' does not conform to protocol 'P2' extension B: P2 { ^ <stdin>:15:1: error: type alias 'X' must be declared public because it matches a requirement in public protocol 'P1' extension B: P2 { ^ main.B:2:22: note: mark the type alias as 'public' to satisfy the requirement public typealias X = main.A ^ <stdin>:10:10: note: protocol requires function 'foo()' with type '() -> ()'; do you want to add a stub? func foo() ^