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diff --git a/testsuite/tests/generics/GenCannotDoRep0_0.hs b/testsuite/tests/generics/GenCannotDoRep0_0.hs
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+++ b/testsuite/tests/generics/GenCannotDoRep0_0.hs
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+{-# LANGUAGE DeriveGeneric              #-}
+{-# LANGUAGE ExistentialQuantification  #-}
+{-# LANGUAGE StandaloneDeriving         #-}
+{-# LANGUAGE FlexibleInstances          #-}
+{-# LANGUAGE TypeFamilies               #-}
+{-# LANGUAGE DatatypeContexts           #-}
+
+module CannotDoRep0_0 where
+
+import GHC.Generics hiding (P, D)
+
+-- We do not support existential quantification
+data Dynamic = forall a. Dynamic a deriving Generic
+
+-- Partial instantiation of types is not allowed
+data P a = P a
+deriving instance Generic (P Int)
+
+-- This gets trickier for data families
+data family D a b
+data instance D Char b
+data instance (Show b) => D Int b
+data instance D () ()
+
+-- Bad: second argument is instantiated
+deriving instance Generic (D Char Char)
+-- Bad: has context
+deriving instance Generic (D Int a)
+-- Ok
+deriving instance Generic (D () ())