Address reviewer comments

Author: odersky

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

@@ -112,8 +112,8 @@ class PostTyper extends MacroTransform with IdentityDenotTransformer  { thisTran
         // If `args` is a list of named argiments, return corresponding type parameters,
         // or abstract types otherwise return type parameters unchanged
         def matchNamed(tparams: List[TypeSymbol], args: List[Tree]): List[Symbol] = args match {
-          case (arg: NamedArg) :: _ =>
-            for (NamedArg(name, arg) <- args) yield tycon.tpe.member(name).symbol
+          case (_: NamedArg) :: _ =>
+            for (NamedArg(name, _) <- args) yield tycon.tpe.member(name).symbol
           case _ =>
             tparams
         }

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

@@ -375,6 +375,7 @@ trait TypeAssigner {
     val tparams = tycon.tpe.typeParams
     def refineNamed(tycon: Type, arg: Tree) = arg match {
       case ast.Trees.NamedArg(name, argtpt) =>
+        // Dotty deviation: importing ast.Trees._ and matching on NamedArg gives a cyclic ref error
         val tparam = tparams.find(_.name == name) match {
           case Some(tparam) => tparam
           case none =>