1 files changed, 29 insertions, 0 deletions
diff --git a/testsuite/tests/typecheck/should_compile/T15549b.hs b/testsuite/tests/typecheck/should_compile/T15549b.hs
new file mode 100644
index 0000000000..ffd4c51d53
--- /dev/null
+++ b/testsuite/tests/typecheck/should_compile/T15549b.hs
@@ -0,0 +1,29 @@
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE PolyKinds #-}
+{-# LANGUAGE DataKinds #-}
+
+module T15549b where
+
+import Data.Kind (Type)
+
+newtype Identity a = Identity a
+newtype Par1 a = Par1 a
+
+data family Sing :: forall k. k -> Type
+data instance Sing :: forall k. k -> Type
+
+type family Rep1 (f :: Type -> Type) :: Type -> Type
+type instance Rep1 Identity = Par1
+
+type family From1 (z :: f a) :: Rep1 f a
+type instance From1 ('Identity x) = 'Par1 x
+
+und :: a
+und = und
+
+f :: forall (a :: Type) (x :: Identity a).  Sing x
+f = g
+    where g :: forall (a :: Type) (f :: Type -> Type) (x :: f a). Sing x
+          g = seq (und :: Sing (From1 x)) und