import Foundation

struct S: Codable {
    let name: String??
}

let a = S(name: "123")
let jsonA = try! JSONEncoder.init().encode(a) // { name: "123" }
let a2 = try! JSONDecoder().decode(S.self, from: jsonA)
assert(a2.name == .some("123"))


let b = S(name: nil)
let jsonB = try! JSONEncoder.init().encode(b) // {}
let b2 = try! JSONDecoder().decode(S.self, from: jsonB)
assert(b2.name == .none)


let c = S(name: .some(nil)) // or .some(.none)
let jsonC = try! JSONEncoder.init().encode(c) // { name: null }
let c2 = try! JSONDecoder().decode(S.self, from: jsonC)
assert(c2.name == .some(.none)) // fails the assertion, because c2.name == .none