1 files changed, 35 insertions, 0 deletions
diff --git a/testsuite/tests/indexed-types/should_compile/T12369.hs b/testsuite/tests/indexed-types/should_compile/T12369.hs
new file mode 100644
index 0000000000..7f4e097ca0
--- /dev/null
+++ b/testsuite/tests/indexed-types/should_compile/T12369.hs
@@ -0,0 +1,35 @@
+{-# language DataKinds, PolyKinds, GADTs, TypeFamilies, RankNTypes,
+             TypeOperators, ConstraintKinds #-}
+
+module T12369 where
+
+import Data.Kind
+
+data family Fix :: (k -> Type) -> k
+newtype instance Fix f = In { out :: f (Fix f) }
+
+type FREE k = (k -> Constraint) -> (k -> k)
+type f  ~> g = forall a. f a -> g a
+type f ~~> g = forall a b. f a b -> g a b
+
+data    family   Free k :: FREE k
+
+newtype instance Free Type k p where
+  Free0 :: (forall q. k q => (p  -> q) -> q) -> Free Type k p
+
+newtype instance Free (j -> Type) k p a where
+  Free1 :: (forall q. k q => (p  ~> q) -> q a) -> Free (j -> Type) k p a
+
+newtype instance Free (j1 -> j2 -> Type) k p a b where
+  Free2 :: (forall q. k q => (p ~~> q) -> q a b) -> Free (j1 -> j2 -> Type) k p a b
+
+data family Free2 :: FREE k
+
+newtype instance Free2 :: FREE Type where
+  Free20 :: (forall q. k q => (p  -> q) -> q) -> Free2 k p
+
+newtype instance Free2 :: forall k. FREE (k -> Type) where
+  Free21 :: (forall q. k q => (p  ~> q) -> q a) -> Free2 k p a
+
+newtype instance Free2 :: forall k1 k2. FREE (k1 -> k2 -> Type) where
+  Free22 :: (forall q. k q => (p ~~> q) -> q a b) -> Free2 k p a b