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Keep correct kind when preparing constraint in stripParams #14761

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Merged
merged 2 commits into from
Mar 24, 2022
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Keep correct kind when preparing constraint in stripParams #14761

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eae8920
Keep correct kind when preparing constraint in stripParams
odersky Mar 23, 2022
c2a7bf5
use topType instead of kind
odersky Mar 23, 2022
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2 changes: 1 addition & 1 deletion compiler/src/dotty/tools/dotc/core/OrderingConstraint.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -248,7 +248,7 @@ class OrderingConstraint(private val boundsMap: ParamBounds,
NoType
case tp: TypeBounds =>
val lo1 = stripParams(tp.lo, todos, !isUpper).orElse(defn.NothingType)
val hi1 = stripParams(tp.hi, todos, isUpper).orElse(defn.AnyKindType)
val hi1 = stripParams(tp.hi, todos, isUpper).orElse(tp.topType)
tp.derivedTypeBounds(lo1, hi1)
case tp: AndType if isUpper =>
val tp1 = stripParams(tp.tp1, todos, isUpper)
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6 changes: 5 additions & 1 deletion compiler/src/dotty/tools/dotc/core/TypeApplications.scala
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Expand Up @@ -229,7 +229,11 @@ class TypeApplications(val self: Type) extends AnyVal {
(alias ne self) && alias.hasSimpleKind
}

/** The top type with the same kind as `self`. */
/** The top type with the same kind as `self`. This is largest type capturing
* the parameter shape of a type without looking at precise bounds.
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In fact, topType does keep around precise bounds (e.g., [X <: Int] =>> Any), though it could be tweaked to map the bounds themselves to topType if needed.

* - The top-type of simple-kinded types is Any
* - A kind like (* -> *) -> * is represented by the top type [X1 <: [X2] =>> Any] =>> Any
*/
def topType(using Context): Type =
if self.hasSimpleKind then
defn.AnyType
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5 changes: 5 additions & 0 deletions tests/pos/i14760.scala
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@@ -0,0 +1,5 @@
enum SUB[-A, +B]:
case Refl[X]() extends SUB[X, X]

def foo[C, A >: C <: C, B](e: SUB[B, A]) = e match
case SUB.Refl() =>