Optionalの記事書きつつちょいとサーベイしてたら見つけてしまったw @swift-5.3.3

let s: String? = .none let t: String?? = s let u: String?? = .none let x = (s as AnyHashable).hashValue let y = (t as AnyHashable).hashValue let z = (u as AnyHashable).hashValue print(s == t, x == y) print(s == u, x == z)