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Fix upper bound constraints, that are higher-kinded #16744

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Merged
merged 1 commit into from
Jan 23, 2023
Merged

Fix upper bound constraints, that are higher-kinded #16744

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7 changes: 5 additions & 2 deletions compiler/src/dotty/tools/dotc/core/TypeComparer.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -1338,8 +1338,11 @@ class TypeComparer(@constructorOnly initctx: Context) extends ConstraintHandling
}
} || tryLiftedToThis2

case _: TypeVar =>
recur(tp1, tp2.superType)
case tv: TypeVar =>
if tv.isInstantiated then
recur(tp1, tp2.superType)
else
compareAppliedType2(tp2, tv.origin, args2)
case tycon2: AnnotatedType if !tycon2.isRefining =>
recur(tp1, tp2.superType)
case tycon2: AppliedType =>
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19 changes: 19 additions & 0 deletions tests/pos/i12478.scala
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Original file line number Diff line number Diff line change
@@ -0,0 +1,19 @@
sealed trait Foo[T]

object Foo:
case class Bar[F[_]](fu: List[F[Unit]]) extends Foo[F[Unit]]

class Test:
def id1[T1](foo1: Foo[T1]): Foo[T1] = foo1 match
case Foo.Bar(fu) =>
Foo.Bar(fu)

def id2[T2](foo2: Foo[T2]): Foo[T2] = foo2 match
case bar2 @ (_: Foo.Bar[f]) =>
val fu2 = bar2.fu
Foo.Bar(fu2)

def id3[T3](foo3: Foo[T3]): Foo[T3] = foo3 match
case bar3 @ Foo.Bar(_) =>
val fu3 = bar3.fu
Foo.Bar(fu3)