Sequence->Seq

1 files changed, 31 insertions, 0 deletions

diff --git a/test/pending/neg/t2180.scala b/test/pending/neg/t2180.scala
new file mode 100644
index 0000000000..a8055bf77d
--- /dev/null
+++ b/test/pending/neg/t2180.scala
@@ -0,0 +1,31 @@
+
+
+Given the following code (which is broken):
+
+class Mxml {
+
+    private def processChildren( children:Seq[Any] ):List[Mxml] = {
+
+        children.toList.flatMap ( e => {
+
+            e match {
+
+                case s:scala.collection.Traversable[_] => s case a => List(a)
+
+            }
+
+        })
+
+    }
+
+}
+
+I get the following error:
+
+Mxml.scala:5: error: could not find implicit value for parameter bf:scala.collection.generic.BuilderFactory[Any,List[Mxml],Sequence[Any]].
+
+    children.flatMap ( e => {
+
+I spent 4 hours failing before I figured out the problem. The return type was wrong. It should have been List[Any].
+
+I have seen similar errors with map. My solution in the past has been to change it to a foldLeft because I have never been able to determine how to fix the problem until now.