お、↓も通った。
protocol Foo {} extension Int: Foo {} protocol P { associatedtype F: Foo func foo() -> F func foos() -> (F, F) } extension P { func foos() -> (F, F) { return (foo(), foo()) } } struct S: P { func foo() -> Int { return Int.random(in: 0..<100) } } let s = S() var (a, b) = s.foos() print(a) a = b print(a)
9 52