Fix #2502: improve warning message of exhaustivity check #2504
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| val explanation = | ||
| hl"""|There are several ways to make the match exhaustive: | ||
| | - add missing cases as shown in the warning | ||
| | - change the return type of irrefutable extractors as `Some[T]` if exist |
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I would say: "- If an extractor always return Some(...), write Some[X] for its return type"
| hl"""|There are several ways to make the match exhaustive: | ||
| | - add missing cases as shown in the warning | ||
| | - change the return type of irrefutable extractors as `Some[T]` if exist | ||
| | - add a wildcard `_` case at the end |
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I would say: "- Add a case _ => ... at the end to match all remaining cases"
| @@ -657,7 +657,7 @@ class SpaceEngine(implicit ctx: Context) extends SpaceLogic { | |||
| else if (tp.classSymbol.is(CaseClass)) | |||
| // use constructor syntax for case class | |||
| showType(tp) + signature(tp).map(_ => "_").mkString("(", ", ", ")") | |||
| else if (signature(tp).nonEmpty) | |||
| else if (sym.is(Flags.Case) && signature(tp).nonEmpty) | |||
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Isn't this condition a superset of the condition of the previous if (if (tp.classSymbol.is(CaseClass))) and so this branch is just dead code?
| @@ -657,7 +657,7 @@ class SpaceEngine(implicit ctx: Context) extends SpaceLogic { | |||
| else if (tp.classSymbol.is(CaseClass)) | |||
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Even if a class is a case class, it might contain a custom unapply, for example:
abstract class BTypes {
trait BType
sealed trait RefBType extends BType {
def classOrArrayType: String = this match {
case ClassBType(internalName) => internalName
case a: ArrayBType => ""
}
}
final case class ClassBType(val internalName: String) extends RefBType
class ArrayBType extends RefBType
object ClassBType {
def unapply(x: RefBType): Option[String] = None
}
}Even with this patch, it warns It would fail on: BTypes.ClassBType(_)
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Good catch, it's more reliable to show just _: T for type space.
| // does the companion object of the given symbol have custom unapply | ||
| def hasCustomUnapply(sym: Symbol): Boolean = { | ||
| val companion = sym.companionModule | ||
| companion.findMember(nme.unapply, NoPrefix, Flags.Synthetic).exists || |
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please use excluded = Synthetic to avoid confusion.
Fix #2502: improve warning message of exhaustivity check