Fix #7392: Interpolate all wildcards in the resulttype of a closure #7396
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…a closure Make sure we interpolate all wildcards in the prototype before making it the result type of an anonymous function. This was done previously only for toplevel wildcards, but not for wildcards nested in some type.
Approximating wildcard types loses too much information. it's better to replace them by fresh typevars instead.
smarter
reviewed
Oct 9, 2019
| def interpolateWildcards = new TypeMap { | ||
| def apply(t: Type) = t match | ||
| case WildcardType => newTypeVar(TypeBounds.empty) | ||
| case WildcardType(bounds: TypeBounds) => newTypeVar(bounds) |
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Could there be WildcardTypes in the bounds themselves that need to be replaced recursively ?
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Maybe. Better to be on the safe side.
smarter
reviewed
Oct 9, 2019
| @@ -833,12 +833,18 @@ class Typer extends Namer | |||
| case _: WildcardType => untpd.TypeTree() | |||
| case _ => untpd.TypeTree(tp) | |||
| } | |||
| def interpolateWildcards = new TypeMap { | |||
| def apply(t: Type) = t match | |||
| case WildcardType => newTypeVar(TypeBounds.empty) | |||
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newTypeVar will call constrained(poly, untpd.EmptyTree, ...) but we do actually have an owning tree that we could use here I think.
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It does not actually change anything. We need an owning tree only to set the position of a TypeVarBinder tree. But in this case we throw the TypeVarBinder away anyway and just keep the type.
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Make sure we interpolate all wildcards in the prototype before making it
the result type of an anonymous function. This was done previously only for
toplevel wildcards, but not for wildcards nested in some type.