1 files changed, 20 insertions, 0 deletions
diff --git a/testsuite/tests/indexed-types/should_compile/T3017.hs b/testsuite/tests/indexed-types/should_compile/T3017.hs
new file mode 100644
index 0000000000..8e4e5bd999
--- /dev/null
+++ b/testsuite/tests/indexed-types/should_compile/T3017.hs
@@ -0,0 +1,20 @@
+{-# LANGUAGE TypeFamilies #-}
+
+-- Trac #3017
+
+module Foo where
+ class Coll c where
+   type Elem c
+   empty :: c
+   insert :: Elem c -> c -> c
+
+ data ListColl a = L [a]
+ instance Coll (ListColl a) where
+   type Elem (ListColl a) = a
+   empty = L []
+   insert x (L xs) = L (x:xs)
+
+ emptyL :: ListColl a
+ emptyL = empty
+
+ test2 c = insert (0, 0) c