package sample

trait T {
  def names(names:List[String], man:Boolean=true):Unit = {}  // これを消すと正常動作
  def names(name:String, man:Boolean=true):Unit = {}
}

object O extends T {
  def call = {
    names("name")  // Error
  }
}

/* Error:
ambiguous reference to overloaded definition, both method names$default$2 in trait T of type => Boolean and  method names$default$2 in trait T of type => Boolean match expected type Boolean
*/