attempt to bind a type parameter for Rep1

compiler/GHC/Tc/Deriv/Generics.hs

@@ -444,14 +444,15 @@ tc_mkRepFamInsts gk tycon inst_tys =
        -- type arguments before generating the Rep/Rep1 instance, since some
        -- of the tyvars might have been instantiated when deriving.
        -- See Note [Generating a correctly typed Rep instance].
-     ; let (env_tyvars, env_inst_args)
+     ; let (rep1_args, env_tyvars, env_inst_args)
              = case gk_ of
-                 Gen0_ -> (tyvars, inst_args)
+                 Gen0_ -> ([], tyvars, inst_args)
                  Gen1_ last_tv
                           -- See the "wrinkle" in
                           -- Note [Generating a correctly typed Rep instance]
-                       -> ( last_tv : tyvars
-                          , anyTypeOfKind (tyVarKind last_tv) : inst_args )
+                       -> ( [last_tv]
+                            , last_tv: tyvars
+                            , mkTyVarTy last_tv : inst_args )
            env        = zipTyEnv env_tyvars env_inst_args
            in_scope   = mkInScopeSet (tyCoVarsOfTypes inst_tys)
            subst      = mkTvSubst in_scope env
@@ -461,7 +462,7 @@ tc_mkRepFamInsts gk tycon inst_tys =
            tvs'       = scopedSort tv'
            cvs'       = scopedSort cv'
            axiom      = mkSingleCoAxiom Nominal rep_name tvs' [] cvs'
-                                        fam_tc inst_tys repTy'
+                                        fam_tc (map mkTyVarTy rep1_args ++ inst_tys) repTy'
 
      ; newFamInst SynFamilyInst axiom  }