??_release.swift

var i: Character?
test("Optional Binding") {
    for _ in 0...repeatCount {
        if let us = s {
            i = us.first
        } else {
            i = "i".first
        }
    }
}
print(String(describing: i))

var j: Character?
test("??") {
    for _ in 0...repeatCount {
        j = (s ?? "j").first
    }
}
print(String(describing: j))