SyntheticMethods: don't generate hashCode for value classes

It will be added by the VCXPrototype parent class

Author: smarter

src/dotty/tools/dotc/transform/SyntheticMethods.scala

@@ -31,7 +31,6 @@ import scala.language.postfixOps
  *  implementation already exists:
  *
  *    def equals(other: Any): Boolean
- *    def hashCode(): Int
  */
 class SyntheticMethods(thisTransformer: DenotTransformer) {
   import ast.tpd._
@@ -41,7 +40,7 @@ class SyntheticMethods(thisTransformer: DenotTransformer) {
 
   private def initSymbols(implicit ctx: Context) =
     if (myValueSymbols.isEmpty) {
-      myValueSymbols = List(defn.Any_hashCode, defn.Any_equals)
+      myValueSymbols = List(defn.Any_equals)
       myCaseSymbols = myValueSymbols ++ List(defn.Any_toString, defn.Product_canEqual,
         defn.Product_productArity, defn.Product_productPrefix)
     }