Fix #16899 #17068
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Fix #16899 #17068
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dwijnand
reviewed
Mar 8, 2023
| @@ -151,6 +151,7 @@ object TypeTestsCasts { | |||
| // always false test warnings are emitted elsewhere | |||
| X.classSymbol.exists && P.classSymbol.exists && | |||
| !X.classSymbol.asClass.mayHaveCommonChild(P.classSymbol.asClass) | |||
| || X.classSymbol.isOneOf(FinalOrSealed) | |||
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Option being sealed doesn't mean that isInstanceOf[Option[Int]] isn't unchecked. Except of course that Unset | Option[Int] without sealed Unset means the scrutinee after case 1 is Option[Int], but I don't think we calculate that in type tests cast, and in a way we can't, because the match tree has been transformed. There's three places (that I'm aware of) where we look at the match trees: typing, pattern match translation, and space engine analysis. Perhaps in one of those we can find a way to annotate that the Option[Int] test is fully checked. Even in the case that isn't not the type of the scrutinee, like:
(v: Unset | Option[Int] | List[Long]) match
case v: Unset =>
case v: Option[Int] =>
case v: List[Long] =>
Was fixed in `3.2.1-RC1`. Add a regression test for scala#10369.
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Should fix #16899