在Scala 2.11中进行模式匹配的穷举检查

Question

我们有一些模式匹配代码,我们期望编译器警告匹配并非详尽无遗,但我们得不到.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))
  }

我们评论了最后两行,但编译器没有发出警告,我们也没有禁用任何检查.

Answer 1

根据Jason Zaugg对SI-9232的评论,卫兵目前似乎只是禁用详尽检查(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.