Rename PolyType.copy method. It clashes with generated one.

See #209 for explanation.

Author: DarkDimius

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

@@ -1999,9 +1999,9 @@ object Types {
 
     def derivedPolyType(paramNames: List[TypeName], paramBounds: List[TypeBounds], restpe: Type)(implicit ctx: Context) =
       if ((paramNames eq this.paramNames) && (paramBounds eq this.paramBounds) && (restpe eq this.resultType)) this
-      else copy(paramNames, paramBounds, restpe)
+      else duplicate(paramNames, paramBounds, restpe)
 
-    def copy(paramNames: List[TypeName] = this.paramNames, paramBounds: List[TypeBounds] = this.paramBounds, restpe: Type)(implicit ctx: Context) =
+    def duplicate(paramNames: List[TypeName] = this.paramNames, paramBounds: List[TypeBounds] = this.paramBounds, restpe: Type)(implicit ctx: Context) =
       PolyType(paramNames)(
           x => paramBounds mapConserve (_.subst(this, x).bounds),
           x => restpe.subst(this, x))

src/dotty/tools/dotc/typer/ProtoTypes.scala

@@ -321,7 +321,7 @@ object ProtoTypes {
       yield new TypeVar(PolyParam(pt, n), state, owningTree)
 
     val added =
-      if (state.constraint contains pt) pt.copy(pt.paramNames, pt.paramBounds, pt.resultType)
+      if (state.constraint contains pt) pt.duplicate(pt.paramNames, pt.paramBounds, pt.resultType)
       else pt
     val tvars = if (owningTree.isEmpty) Nil else newTypeVars(added)
     state.constraint = state.constraint.add(added, tvars)