bug715.check

来自「JAVA 语言的函数式编程扩展」· CHECK 代码 · 共 5 行

bug715.scala:12: error: method chilren in trait NodeImpl is accessed from super. It may not be abstract unless it is overridden by a member declared `abstract' and `override'
    override def children = super.chilren;
                                  ^
one error found