scala - Scala 2.11 模式匹配的详尽检查

Question

我们有一些模式匹配代码，我们希望编译器警告我们匹配不是详尽的，但我们没有得到。是否存在无法进行详尽检查的情况？

例如我们的例子(使用 scalactic Good+Bad):

(maybeModelIdOrFailure, maybeMake) match {

    case (Some(Good(modelId)), Some(makeId)) if modelId >= 0 && taxonomyService.isValidModel(makeId, modelId) =>
      Good(Some(MakeModelParameters(makeId, Some(modelId), modelLineId = None, index)))

    case (Some(Good(modelLineId)), Some(makeId)) if modelLineId < 0 && taxonomyService.isValidModelLine(makeId, -1 * modelLineId) =>
      Good(Some(MakeModelParameters(makeId, modelId = None, modelLineId = Some(-1 * modelLineId), index)))

    case (Some(Good(modelOrModelLineId)), Some(makeId)) =>
      Bad(One(IdNotFound(modelIdKeyName, modelOrModelLineId)))

    case (Some(Good(modelId)), None) if modelId >= 0 =>
      Bad(One(IdInvalid(modelIdKeyName, "Model Id without Make Id")))

    case (Some(Good(modelLineId)), None) if modelLineId < 0 =>
      Bad(One(IdInvalid(modelIdKeyName, "Model Line Id without Make Id")))

    case (None, Some(makeId)) => Good(Some(MakeModelParameters(makeId, None, None, index)))

    // case (None, None) => Good(None)

    // case (Some(Bad(invalidParams)), _) => Bad(One(invalidParams))
  }

我们注释了最后两行，但编译器没有警告，我们也没有禁用任何检查。

Answer 1

来自 Jason Zaugg's comment on SI-9232似乎守卫目前只是禁用详尽检查(或几乎如此)。如果这是原因，移动分支内的保护条件(例如 case (Some(Good(modelId)), None) => if (modelId >= 0) ... else ... )应该会有所帮助。其他相关问题:https://issues.scala-lang.org/browse/SI-5365 , https://issues.scala-lang.org/browse/SI-7631 .