New test and drop println

Author: odersky

compiler/src/dotty/tools/dotc/typer/PrepareTransparent.scala

@@ -318,7 +318,6 @@ object PrepareTransparent {
                 case tp: NamedType if tp.prefix.member(sym.name).isOverloaded =>
                   // refer to prefix instead of to ident directly, so that overloading can be resolved
                   // again at expansion site
-                  println(i"RECORD start for $tree")
                   typeAtPos(tree.pos.startPos) = tp.prefix
                 case _ =>
                   typeAtPos(tree.pos.toSynthetic) = tree.tpe

tests/run/typelevel-vector1.scala

@@ -0,0 +1,30 @@
+object typelevel {
+  case class Typed[T](value: T) { type Type = T }
+  erased def erasedValue[T]: T = ???
+}
+
+trait Nat
+case object Z extends Nat
+case class S[N <: Nat](n: N) extends Nat
+
+case class Vec[T, N <: Nat](elems: List[T])
+
+object Test {
+  import typelevel._
+  type Z = Z.type
+
+  transparent def add(x: Nat, y: Nat): Nat = x match {
+    case Z => y
+    case S(x1) => S(add(x1, y))
+  }
+
+  val x = S(S(Z))
+  val y = add(x, x)
+  val z: S[S[S[S[Z]]]] = y
+
+  transparent def concat[T, N1 <: Nat, N2 <: Nat](xs: Vec[T, N1], ys: Vec[T, N2]): Vec[T, _] = {
+    val length = Typed(add(erasedValue[N1], erasedValue[N2]))
+    Vec[T, length.Type](xs.elems ++ ys.elems)
+  }
+}
+