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Fix #1590: Eliminate wildcards when approximating a type #1592

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Merged
merged 2 commits into from
Oct 16, 2016
Merged

Fix #1590: Eliminate wildcards when approximating a type #1592

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a45a3e5
Fix #1590: Eliminate wildcards when approximating a type
odersky Oct 13, 2016
5d531ec
Refinement of interpolation direction
odersky Oct 13, 2016
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6 changes: 5 additions & 1 deletion src/dotty/tools/dotc/core/ConstraintHandling.scala
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Expand Up @@ -162,7 +162,8 @@ trait ConstraintHandling {
/** Solve constraint set for given type parameter `param`.
* If `fromBelow` is true the parameter is approximated by its lower bound,
* otherwise it is approximated by its upper bound. However, any occurrences
* of the parameter in a refinement somewhere in the bound are removed.
* of the parameter in a refinement somewhere in the bound are removed. Also
* wildcard types in bounds are approximated by their upper or lower bounds.
* (Such occurrences can arise for F-bounded types).
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This should be moved before the sentence you added

* The constraint is left unchanged.
* @return the instantiating type
Expand All @@ -174,6 +175,9 @@ trait ConstraintHandling {
def apply(tp: Type) = mapOver {
tp match {
case tp: RefinedType if param occursIn tp.refinedInfo => tp.parent
case tp: WildcardType =>
val bounds = tp.optBounds.orElse(TypeBounds.empty).bounds
if (fromBelow == (variance >= 0)) bounds.lo else bounds.hi
case _ => tp
}
}
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1 change: 1 addition & 0 deletions tests/pos/i1590.scala
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@@ -0,0 +1 @@
case class W[T](seq: Option[Option[T]] = Option.empty)