Avoid using TypeBounds in alias refinements.

The idea is to use the alias itself. This cuts down on # of typebounds created and makes operations on refined infos and applied types more direct.

1 files changed, 8 insertions, 7 deletions

diff --git a/src/dotty/tools/dotc/core/pickling/UnPickler.scala b/src/dotty/tools/dotc/core/pickling/UnPickler.scala
index 78a91b2ef..e5cbdf53b 100644
--- a/src/dotty/tools/dotc/core/pickling/UnPickler.scala
+++ b/src/dotty/tools/dotc/core/pickling/UnPickler.scala
@@ -560,15 +560,16 @@ class UnPickler(bytes: Array[Byte], classRoot: ClassDenotation, moduleClassRoot:
     def elim(tp: Type): Type = tp match {
       case tp @ RefinedType(parent, name) =>
         val parent1 = elim(tp.parent)
-        tp.refinedInfo match {
-          case TypeAlias(info: TypeRef) if boundSyms contains info.symbol =>
-            RefinedType(parent1, name, info.symbol.info)
+        tp.compactInfo match {
           case info: TypeRef if boundSyms contains info.symbol =>
             val info1 = info.symbol.info
-            assert(info1.derivesFrom(defn.SingletonClass))
-            RefinedType(parent1, name, info1.mapReduceAnd(removeSingleton)(_ & _))
-          case info =>
-            tp.derivedRefinedType(parent1, name, info)
+            if (tp.isAliasRefinement) RefinedType(parent1, name, info1)
+            else {
+              assert(info1.derivesFrom(defn.SingletonClass))
+              RefinedType(parent1, name, info1.mapReduceAnd(removeSingleton)(_ & _))
+            }
+          case cinfo =>
+            tp.derivedRefinedType(parent1, name, cinfo)
         }
       case _ =>
         tp