Optional(42)stderr:
<stdin>:2:19: warning: expression implicitly coerced from 'Int?' to 'Any' defer { print(a) } // ←まだaが宣言されてないよ…？ <stdin>:2:19: note: provide a default value to avoid this warning defer { print(a) } // ←まだaが宣言されてないよ…？ <stdin>:2:19: note: force-unwrap the value to avoid this warning defer { print(a) } // ←まだaが宣言されてないよ…？ <stdin>:2:19: note: explicitly cast to 'Any' with 'as Any' to silence this warning defer { print(a) } // ←まだaが宣言されてないよ…？ <stdin>:4:15: warning: variable 'a' was written to, but never read guard var a = a else { return } ^