1 files changed, 13 insertions, 0 deletions
diff --git a/test/files/pos/t3731.scala b/test/files/pos/t3731.scala
new file mode 100644
index 0000000000..9a617012b3
--- /dev/null
+++ b/test/files/pos/t3731.scala
@@ -0,0 +1,13 @@
+object Test{
+  trait ZW[S]{type T}
+  def ZipWith[S, M <: ZW[S]]: M#T = error("ZW")
+
+  // meh must be parameterised to force an asSeenFrom that
+  // duplicates the refinement in the TR's pre without updating its sym
+  def meh[A] = ZipWith[A, ZW[A]{type T=Stream[A]}]
+
+  meh[Int]: Stream[Int]
+}
+// debugging output in coevolveSym should say:
+// coevolved type T#11029 : Stream#3234[A#9228] to type T#11277 : Stream#3234[A#9227]
+// with Test.ZW#9219[A#9228]{type T#11029 = Stream#3234[A#9228]} -> Test.ZW#9219[A#9227]{type T#11277 = Stream#3234[A#9227]}