blackbox restriction #1: can't refine the official return type

When an application of a blackbox macro expands into a tree `x`,
the expansion is wrapped into a type ascription `(x: T)`, where `T` is
the declared return type of the blackbox macro with type arguments and
path dependencies applied in consistency with the particular macro
application being expanded.

This invalidates blackbox macros as an implementation vehicle
of type providers.

1 files changed, 2 insertions, 2 deletions

diff --git a/test/files/run/macro-expand-unapply-a/Impls_Macros_1.scala b/test/files/run/macro-expand-unapply-a/Impls_Macros_1.scala
index b837ffc43b..7bfff374e2 100644
--- a/test/files/run/macro-expand-unapply-a/Impls_Macros_1.scala
+++ b/test/files/run/macro-expand-unapply-a/Impls_Macros_1.scala
@@ -1,11 +1,11 @@
-import scala.reflect.macros.BlackboxContext
+import scala.reflect.macros.WhiteboxContext
 
 object Helper {
   def unapplySeq[T](x: List[T]): Option[Seq[T]] = List.unapplySeq[T](x)
 }
 
 object Macros {
-  def impl[T: c.WeakTypeTag](c: BlackboxContext)(x: c.Expr[List[T]]) = {
+  def impl[T: c.WeakTypeTag](c: WhiteboxContext)(x: c.Expr[List[T]]) = {
     c.universe.reify(Helper.unapplySeq(x.splice))
   }