Remove refinement encoding of hk types

Remove the code that implemented the encoding of hk types
using refinements.

Author: odersky

src/dotty/tools/dotc/config/Config.scala

@@ -10,8 +10,6 @@ object Config {
 
   final val checkCacheMembersNamed = false
 
-  final val newHK = true
-
   /** When updating a constraint bound, check that the constrained parameter
    *  does not appear at the top-level of either of its bounds.
    */

src/dotty/tools/dotc/core/ConstraintHandling.scala

@@ -286,8 +286,6 @@ trait ConstraintHandling {
           if (!addParamBound(bound)) NoType
           else if (fromBelow) defn.NothingType
           else defn.AnyType
-        case bound: RefinedType if !Config.newHK =>
-          bound.normalizeHkApplyOLD
         case _ =>
           bound
       }

src/dotty/tools/dotc/core/NameOps.scala

@@ -100,21 +100,6 @@ object NameOps {
         name.length > 0 && name.last == '=' && name.head != '=' && isOperatorPart(name.head)
     }
 
-    /** Is this the name of a higher-kinded type parameter of a Lambda? */
-    def isHkArgNameOLD =
-      name.length > 0 &&
-      name.head == tpnme.hkArgPrefixHeadOLD &&
-      name.startsWith(tpnme.hkArgPrefixOLD) && {
-        val digits = name.drop(tpnme.hkArgPrefixLengthOLD)
-        digits.length <= 4 && digits.forall(_.isDigit)
-      }
-
-    /** The index of the higher-kinded type parameter with this name.
-     *  Pre: isLambdaArgName.
-     */
-    def hkArgIndexOLD: Int =
-      name.drop(tpnme.hkArgPrefixLengthOLD).toString.toInt
-
     /** If the name ends with $nn where nn are
       * all digits, strip the $ and the digits.
       * Otherwise return the argument.

src/dotty/tools/dotc/core/StdNames.scala

@@ -529,10 +529,6 @@ object StdNames {
 
     val synthSwitch: N          = "$synthSwitch"
 
-    val hkArgPrefixOLD: N          = "$hk"
-    val hkArgPrefixHeadOLD: Char   = hkArgPrefixOLD.head
-    val hkArgPrefixLengthOLD: Int  = hkArgPrefixOLD.length
-
     // unencoded operators
     object raw {
       final val AMP  : N  = "&"
@@ -746,8 +742,6 @@ object StdNames {
     def syntheticLambdaParamNames(num: Int): List[TypeName] =
       (0 until num).map(syntheticLambdaParamName)(breakOut)
 
-    def hkArgOLD(n: Int): TypeName = hkArgPrefixOLD ++ n.toString
-
     final val Conforms = encode("<:<")
   }