Function overloading swift bug

FunctionOverloading.swift

// Doesn't work.
func doBimpy(f1: Bimpy, _ f2: Bimpy) -> Bimpy {
  return Bimpy()
}

// Works
func doBimpy2(f1: Bimpy, _ f2: Bimpy) -> Bimpy {
  return Bimpy()
}

class Bimpy {
  func doBimpy() -> Bimpy {
    return Bimpy()
  }

  func doBimpyWith(f: Bimpy) -> Bimpy {
    return doBimpy(self, f)
  }

  func doBimpyWith2(f: Bimpy) -> Bimpy {
    return doBimpy2(self, f)
  }
}