protocol From { associated Convertible static func from(_ x: Convertible) -> Self } protocol AConvertible {} struct A: From { typealias Convertible = AConvertible static func from(_ x: Convertible) -> A { // ... } }protocol From { associated Convertible static func from(_ x: Convertible) -> Self } protocol AConvertible {} struct A: From { typealias Convertible = AConvertible static func from(_ x: Convertible) -> A { // ... } }