Move stripLazyRef inside simplified

Author: dwijnand

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

@@ -3261,7 +3261,7 @@ class TrackingTypeComparer(initctx: Context) extends TypeComparer(initctx) {
             // then TypeComparer will eventually start returning `false` for `isSubType`.
             // Or, under -Yno-deep-subtypes, start throwing AssertionErrors.
             // So, we eagerly strip that lazy ref here to avoid the stacking.
-            tp.stripLazyRef.simplified
+            tp.simplified
       case Nil =>
         val casesText = MatchTypeTrace.noMatchesText(scrut, cases)
         ErrorType(reporting.MatchTypeNoCases(casesText))

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

@@ -1984,7 +1984,11 @@ object Types {
      *  this method handles this by never simplifying inside a `MethodicType`,
      *  except for replacing type parameters with associated type variables.
      */
-    def simplified(using Context): Type = TypeOps.simplify(this, null)
+    def simplified(using Context): Type =
+      // stripping LazyRef is important for the reduction of applied match types
+      // see the comment in matchCases/recur for more details
+      val tp = stripLazyRef
+      TypeOps.simplify(tp, null)
 
     /** Compare `this == that`, assuming corresponding binders in `bs` are equal.
      *  The normal `equals` should be equivalent to `equals(that, null`)`.