struct S {
    func foo() -> UInt { return 0 }
    func foo<T: UnsignedInteger>(bar: T) -> T {
        return bar
    }
}

let s = S()
let a = s.foo() // OK
let b = s.foo(bar: 123) // ERR: Argument passed to call that takes no arguments
let c: UInt = s.foo(bar: 123) // OK
let d = s.foo(bar: 123 as UInt) // OK