1 files changed, 37 insertions, 0 deletions
diff --git a/test/files/pos/hk-infer.scala b/test/files/pos/hk-infer.scala
new file mode 100644
index 0000000000..30e3476404
--- /dev/null
+++ b/test/files/pos/hk-infer.scala
@@ -0,0 +1,37 @@
+object Basis {
+  final case class X[T](t: T)
+  val x  = Seq(X(32))
+  val y  = Seq(X(true))
+  val x1 = Seq(X("asdf"))
+  val x2 = Seq(X('d'))
+}
+import Basis._
+
+object DoesWork {
+  // Doesn'tWork
+  // def f1 = x ++ y ++ x1 ++ x2
+
+  def f2 = List(x, y, x1, x2).flatten
+}
+
+// Testing the not giving of explicit Booper[M] arguments.
+object ShouldWorkHK {
+  class Booper[M[_]](xs: Seq[M[_]]) extends collection.generic.SeqForwarder[M[_]] {
+    def underlying = xs
+    def BOOP(ys: Seq[M[_]]) = new Booper(xs ++ ys)
+  }
+  implicit def mkBoop[M[_]](xs: Seq[M[_]]) = new Booper(xs)
+
+  def f1 = x BOOP y BOOP x1 BOOP x2
+}
+
+object DoesWorkHK {
+  class Booper[M[_]](xs: Seq[M[_]]) extends collection.generic.SeqForwarder[M[_]] {
+    def underlying = xs
+    def BOOP(ys: Seq[M[_]]) = new Booper[M](xs ++ ys)
+  }
+  implicit def mkBoop[M[_]](xs: Seq[M[_]]) = new Booper[M](xs)
+
+  def f1 = x BOOP y BOOP x1 BOOP x2
+}
+