Handle Range cases when reducing match types

compiler/src/dotty/tools/dotc/core/TypeComparer.scala

@@ -2912,6 +2912,8 @@ class TrackingTypeComparer(initctx: Context) extends TypeComparer(initctx) {
         case cas: HKTypeLambda =>
           caseLambda = constrained(cas)
           caseLambda.resultType
+        case _: Range =>
+          return Some(NoType)
         case _ =>
           cas
       }

compiler/src/dotty/tools/dotc/core/Types.scala

@@ -5989,7 +5989,7 @@ object Types {
   /** A range of possible types between lower bound `lo` and upper bound `hi`.
    *  Only used internally in `ApproximatingTypeMap`.
    */
-  private case class Range(lo: Type, hi: Type) extends UncachedGroundType {
+  private[core] case class Range(lo: Type, hi: Type) extends UncachedGroundType {
     assert(!lo.isInstanceOf[Range])
     assert(!hi.isInstanceOf[Range])
 

tests/neg/i15362.scala

@@ -0,0 +1,17 @@
+import scala.compiletime.*
+import scala.compiletime.ops.int.*
+
+abstract sealed class HList :
+  def ::[H](head: H): HNonEmpty[H, this.type] = HNonEmpty(head, this)
+
+case object HNil extends HList
+case class HNonEmpty[H, T <: HList](head: H, tail: T) extends HList :
+  type Elem[N <: Int] =
+    N match
+      case 0 => H
+      case S[n1] => Elem[n1]
+
+  inline def apply[N <: Int](n: N): Elem[N] =
+    n match
+      case _: 0 => head
+      case _: S[n1] => tail.asInstanceOf[HNonEmpty[?, ?]].apply(constValue[n1]) // error