3 files changed, 22 insertions, 17 deletions
diff --git a/src/dotty/tools/dotc/core/TypeComparer.scala b/src/dotty/tools/dotc/core/TypeComparer.scala
index 1d2d4bac9..a8ad580a7 100644
--- a/src/dotty/tools/dotc/core/TypeComparer.scala
+++ b/src/dotty/tools/dotc/core/TypeComparer.scala
@@ -163,7 +163,8 @@ class TypeComparer(initctx: Context) extends DotClass {
    */
   def approximation(param: PolyParam, fromBelow: Boolean): Type = {
     val avoidParam = new TypeMap {
-      override def apply(tp: Type) = mapOver {
+      override def stopAtStatic = true
+      def apply(tp: Type) = mapOver {
         tp match {
           case tp: RefinedType if param occursIn tp.refinedInfo => tp.parent
           case _ => tp
@@ -269,18 +270,16 @@ class TypeComparer(initctx: Context) extends DotClass {
         def compareNamed = tp1 match {
           case tp1: NamedType =>
             val sym1 = tp1.symbol
-            val sym2 = tp2.symbol
-            val pre1 = tp1.prefix
-            val pre2 = tp2.prefix
-
-            ( if (sym1 == sym2) (
-                ctx.erasedTypes
+            ( if (sym1 == tp2.symbol) (
+                   ctx.erasedTypes
                 || sym1.isStaticOwner
-                || isSubType(pre1, pre2)
-                || pre1.isInstanceOf[ThisType] && pre2.isInstanceOf[ThisType]
-                )
-              else
-                tp1.name == tp2.name && isSubType(pre1, pre2)
+                || { val pre1 = tp1.prefix
+                     val pre2 = tp2.prefix
+                     isSubType(pre1, pre2) ||
+                     pre1.isInstanceOf[ThisType] && pre2.isInstanceOf[ThisType]
+                   }
+              ) else
+                tp1.name == tp2.name && isSubType(tp1.prefix, tp2.prefix)
             ) || secondTryNamed(tp1, tp2)
           case _ =>
             secondTry(tp1, tp2)
diff --git a/src/dotty/tools/dotc/core/TypeOps.scala b/src/dotty/tools/dotc/core/TypeOps.scala
index 6e984e43c..afa39f2a3 100644
--- a/src/dotty/tools/dotc/core/TypeOps.scala
+++ b/src/dotty/tools/dotc/core/TypeOps.scala
@@ -50,8 +50,11 @@ trait TypeOps { this: Context =>
   /** Implementation of Types#simplified */
   final def simplify(tp: Type, theMap: SimplifyMap): Type = tp match {
     case tp: NamedType =>
-      tp.derivedSelect(simplify(tp.prefix, theMap))
-    case  _: ThisType | NoPrefix =>
+      if (tp.symbol.isStatic) tp
+      else tp.derivedSelect(simplify(tp.prefix, theMap))
+    case tp: PolyParam =>
+      typerState.constraint.typeVarOfParam(tp) orElse tp
+    case  _: ThisType | _: BoundType | NoPrefix =>
       tp
     case tp: RefinedType =>
       tp.derivedRefinedType(simplify(tp.parent, theMap), tp.refinedName, simplify(tp.refinedInfo, theMap))
@@ -59,8 +62,6 @@ trait TypeOps { this: Context =>
       simplify(l, theMap) & simplify(r, theMap)
     case OrType(l, r) =>
       simplify(l, theMap) | simplify(r, theMap)
-    case tp: PolyParam =>
-      typerState.constraint.typeVarOfParam(tp) orElse tp
     case _ =>
       (if (theMap != null) theMap else new SimplifyMap).mapOver(tp)
   }
diff --git a/src/dotty/tools/dotc/core/Types.scala b/src/dotty/tools/dotc/core/Types.scala
index b99162383..bacbe4f9d 100644
--- a/src/dotty/tools/dotc/core/Types.scala
+++ b/src/dotty/tools/dotc/core/Types.scala
@@ -2080,6 +2080,8 @@ object Types {
 
   abstract class TypeMap(implicit ctx: Context) extends (Type => Type) { thisMap =>
 
+    protected def stopAtStatic = true
+
     def apply(tp: Type): Type
 
     protected var variance = 1
@@ -2087,7 +2089,8 @@ object Types {
     /** Map this function over given type */
     def mapOver(tp: Type): Type = tp match {
       case tp: NamedType =>
-        tp.derivedSelect(this(tp.prefix))
+        if (stopAtStatic && tp.symbol.isStatic) tp
+        else tp.derivedSelect(this(tp.prefix))
 
       case _: ThisType
          | _: BoundType
@@ -2173,6 +2176,7 @@ object Types {
       tp.derivedClassInfo(this(tp.prefix))
 
     def andThen(f: Type => Type): TypeMap = new TypeMap {
+      override def stopAtStatic = thisMap.stopAtStatic
       def apply(tp: Type) = f(thisMap(tp))
     }
   }
@@ -2191,6 +2195,7 @@ object Types {
   }
 
   object IdentityTypeMap extends TypeMap()(NoContext) {
+    override def stopAtStatic = true
     def apply(tp: Type) = tp
   }