Fix unreachable warning in deeply nested sealed hierarchy #18706
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Without applying we were constructing the type Jacket#Body, instead of Jacket[?]#Body, which lead down to an incorrect isSubSpace calculation and thus an unreachable warning.
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| @@ -883,7 +883,7 @@ object TypeOps: | |||
| else if symbol.is(Module) then | |||
| TermRef(this(tref.prefix), symbol.sourceModule) | |||
| else if (prefixTVar != null) | |||
| this(tref) | |||
| this(tref.applyIfParameterized(tref.typeParams.map(_ => WildcardType))) | |||
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It's not clear why this is correct.
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I tried to detail it in the commit message (9460b7d) - given something like:
class Jacket[T]:
sealed trait BodyTypeAs we map over the type Jacket.this.BodyType we don't want to take the raw type Jacket, stripped from its ThisType wrapper, and have it be the prefix of BodyType, because we would then get Jacket#BodyType which is ill-formed. Instead we mean to refer to any the BodyType nested class of any Jacket: Jacket[?]#BodyType.
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Thanks for the explanation. I now see the type will be upper bound for prefixTVar, so it's harmless.
| @@ -883,7 +883,7 @@ object TypeOps: | |||
| else if symbol.is(Module) then | |||
| TermRef(this(tref.prefix), symbol.sourceModule) | |||
| else if (prefixTVar != null) | |||
| this(tref) | |||
| this(tref.applyIfParameterized(tref.typeParams.map(_ => WildcardType))) | |||
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Thanks for the explanation. I now see the type will be upper bound for prefixTVar, so it's harmless.
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