1 files changed, 26 insertions, 0 deletions
diff --git a/testsuite/tests/gadt/gadt22.hs b/testsuite/tests/gadt/gadt22.hs
new file mode 100644
index 0000000000..f456198ff1
--- /dev/null
+++ b/testsuite/tests/gadt/gadt22.hs
@@ -0,0 +1,26 @@
+{-# LANGUAGE GADTs, ExistentialQuantification, KindSignatures, Rank2Types #-}
+
+-- Succeeds (needs the (Ord a) in TypeSet 
+-- c.f. gadt21.hs
+
+-- However, it's a useful test because it unearthed a bug
+-- in free-variable-finding
+
+module Expr where
+
+import Data.Set (Set)
+
+data Type a where
+    TypeInt     :: Type Int
+    TypeSet     :: Ord a => Type a -> Type (Set a)
+    TypeFun     :: Type a -> Type b -> Type (a -> b)
+
+data Expr :: * -> * where
+    Const :: Type a -> a -> Expr a
+
+data DynExpr = forall a. DynExpr (Expr a)
+
+withOrdDynExpr :: DynExpr -> (forall a. Ord a => Expr a -> b) -> Maybe b
+withOrdDynExpr (DynExpr e@(Const (TypeSet _) _)) f = Just (f e)
+withOrdDynExpr (DynExpr e@(Const TypeInt _)) f = Just (f e)
+withOrdDynExpr _ _ = Nothing