1 files changed, 7 insertions, 2 deletions
diff --git a/src/continuations/plugin/scala/tools/selectivecps/CPSUtils.scala b/src/continuations/plugin/scala/tools/selectivecps/CPSUtils.scala
index 90c961f195..46c644bcd6 100644
--- a/src/continuations/plugin/scala/tools/selectivecps/CPSUtils.scala
+++ b/src/continuations/plugin/scala/tools/selectivecps/CPSUtils.scala
@@ -96,8 +96,13 @@ trait CPSUtils {
 
   // anf transform
 
-  def getExternalAnswerTypeAnn(tp: Type) =
-    cpsParamTypes(tp) orElse None
+  def getExternalAnswerTypeAnn(tp: Type) = {
+    cpsParamTypes(tp) orElse {
+      if (hasPlusMarker(tp))
+        global.warning("trying to instantiate type " + tp + " to unknown cps type")
+      None
+    }
+  }
 
   def getAnswerTypeAnn(tp: Type): Option[(Type, Type)] =
     cpsParamTypes(tp) filterNot (_ => hasPlusMarker(tp))