fix #6663: sort EnumValues by ordinal

Author: bishabosha

library/src/scala/runtime/EnumValues.scala

@@ -1,9 +1,9 @@
 package scala.runtime
 
-import scala.collection.immutable.Map
+import scala.collection.immutable.TreeMap
 
 class EnumValues[E <: Enum] {
-  private[this] var myMap: Map[Int, E] = Map()
+  private[this] var myMap: Map[Int, E] = TreeMap.empty
   private[this] var fromNameCache: Map[String, E] = null
 
   def register(v: E) = {

tests/run/enum-values-order.scala

@@ -0,0 +1,8 @@
+/** immutable hashmaps (as of 2.13 collections) only store up to 4 entries in insertion order */
+enum LatinAlphabet { case A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z }
+
+@main def Test =
+  import LatinAlphabet._
+  val ordered = Seq(A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z)
+
+  assert(ordered sameElements LatinAlphabet.values)