1 files changed, 43 insertions, 0 deletions
diff --git a/testsuite/tests/patsyn/should_fail/T14552.hs b/testsuite/tests/patsyn/should_fail/T14552.hs
new file mode 100644
index 0000000000..a4a7493530
--- /dev/null
+++ b/testsuite/tests/patsyn/should_fail/T14552.hs
@@ -0,0 +1,43 @@
+{-# Language RankNTypes, ViewPatterns, PatternSynonyms, TypeOperators, ScopedTypeVariables,
+             KindSignatures, PolyKinds, DataKinds, TypeFamilies, GADTs #-}
+
+module T14552 where
+
+import Data.Kind
+import Data.Proxy
+
+data family Sing a
+
+type a --> b = (a, b) -> Type
+
+type family F (f::a --> b) (x::a) :: b
+
+newtype Limit :: (k --> Type) -> Type where
+  Limit :: (forall xx. Proxy xx -> F f xx) -> Limit f
+
+data Exp :: [Type] -> Type -> Type where
+  TLam :: (forall aa. Proxy aa -> Exp xs (F w aa))
+        -> Exp xs (Limit w)
+
+pattern FOO f <- TLam (($ Proxy) -> f)
+
+
+{-
+TLam :: forall (xs::[Type]) (b::Type).   -- Universal
+         forall k (w :: k --> Type).      -- Existential
+         (b ~ Limit w) =>
+         => (forall (aa :: k). Proxy aa -> Exp xs (F w aa))
+         -> Exp xs b
+
+-}
+
+{-
+mfoo :: Exp xs b
+     -> (forall k (w :: k --> Type).
+         (b ~ Limit w)
+         => Exp xs (F w aa)
+         -> r)
+     -> r
+mfoo scrut k = case srcut of
+                 TLam g -> k (g Proxy)
+-}