1 files changed, 25 insertions, 0 deletions
diff --git a/testsuite/tests/typecheck/should_fail/T18851c.hs b/testsuite/tests/typecheck/should_fail/T18851c.hs
new file mode 100644
index 0000000000..f633d4674d
--- /dev/null
+++ b/testsuite/tests/typecheck/should_fail/T18851c.hs
@@ -0,0 +1,25 @@
+{-# LANGUAGE DataKinds                #-}
+{-# LANGUAGE GADTs                    #-}
+{-# LANGUAGE PolyKinds                #-}
+{-# LANGUAGE StandaloneKindSignatures #-}
+{-# LANGUAGE TypeFamilyDependencies   #-}
+{-# LANGUAGE TypeOperators            #-}
+
+-- from https://gitlab.haskell.org/ghc/ghc/-/merge_requests/5899#note_407871
+
+module T18851c where
+
+-- base
+import           Data.Kind (Type)
+
+data Nat
+type Plus1 :: Nat -> Nat
+type family Plus1 n = r | r -> n
+
+data V (n :: Nat) = V
+
+data VSucc n where
+  VSucc :: V n -> VSucc (Plus1 n)
+
+foo :: VSucc n -> VSucc n -> VSucc n
+foo (VSucc _) (VSucc _) = VSucc V