Address review comments

Author: odersky

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

@@ -663,7 +663,7 @@ object Denotations {
             tp1.derivedLambdaType(
               mergeParamNames(tp1, tp2),
               tp1.paramInfos,
-              tp1.resultType | tp2.resultType.subst(tp2, tp1))
+              infoJoin(tp1.resultType, tp2.resultType.subst(tp2, tp1), sym1, sym2))
           case _ =>
             mergeConflict(sym1, sym2, tp1, tp2)
         }
@@ -676,7 +676,7 @@ object Denotations {
               tp1.paramInfos.zipWithConserve(tp2.paramInfos) { (p1, p2) =>
                 (p1 | p2.subst(tp2, tp1)).bounds
               },
-              tp1.resultType | tp2.resultType.subst(tp2, tp1))
+              infoJoin(tp1.resultType, tp2.resultType.subst(tp2, tp1), sym1, sym2))
           case _ =>
             mergeConflict(sym1, sym2, tp1, tp2)
         }

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

@@ -1643,12 +1643,13 @@ class TypeComparer(initctx: Context) extends ConstraintHandling {
     case tp1: RefinedType =>
       tp2 match {
         case tp2: RefinedType if tp1.refinedName == tp2.refinedName =>
-          val jointInfo =
-            try Denotations.infoMeet(tp1.refinedInfo, tp2.refinedInfo, NoSymbol, NoSymbol, safeIntersection = false)
-              catch {
-                case ex: MergeError => NoType
-              }
-          tp1.derivedRefinedType(tp1.parent & tp2.parent, tp1.refinedName, jointInfo)
+          try {
+            val jointInfo = Denotations.infoMeet(tp1.refinedInfo, tp2.refinedInfo, NoSymbol, NoSymbol, safeIntersection = false)
+            tp1.derivedRefinedType(tp1.parent & tp2.parent, tp1.refinedName, jointInfo)
+          }
+          catch {
+            case ex: MergeError => tp1.parent & tp2.parent
+          }
         case _ =>
           NoType
       }