当我将包装定义为值类(扩展anyval)时:
class Wrapper(val string: String) extends AnyVal
def wrapperHolder(w: Wrapper): {def wrapper: Wrapper} = new {
def wrapper: Wrapper = w
}
wrapperholder的编译错误如下:
Error:(5, 22) Result type in structural refinement may not refer to a user-defined value class
def wrapper: Wrapper = w
