FIX Trac #1901: check no existential context in H98 mode

[ghc-hetmet.git] / compiler / typecheck / TcBinds.lhs

diff --git a/compiler/typecheck/TcBinds.lhs b/compiler/typecheck/TcBinds.lhs
index ba4bfc6..d0044d4 100644 (file)
--- a/compiler/typecheck/TcBinds.lhs
+++ b/compiler/typecheck/TcBinds.lhs
@@ -42,7 +42,7 @@ import VarEnv
 import TysPrim
 import Id
 import IdInfo
-import Var ( TyVar )
+import Var ( TyVar, varType )
 import Name
 import NameSet
 import NameEnv
@@ -344,15 +344,15 @@ tcPolyBinds top_lvl sig_fn prag_fn rec_group rec_tc binds
           generalise dflags top_lvl bind_list sig_fn mono_bind_infos lie_req
 
        -- BUILD THE POLYMORPHIC RESULT IDs
-  ; let dict_ids = map instToId dicts
-  ; exports <- mapM (mkExport top_lvl prag_fn tyvars_to_gen (map idType dict_ids))
+  ; let dict_vars = map instToVar dicts        -- May include equality constraints
+  ; exports <- mapM (mkExport top_lvl prag_fn tyvars_to_gen (map varType dict_vars))
                    mono_bind_infos
 
   ; let        poly_ids = [poly_id | (_, poly_id, _, _) <- exports]
   ; traceTc (text "binding:" <+> ppr (poly_ids `zip` map idType poly_ids))
 
   ; let abs_bind = L loc $ AbsBinds tyvars_to_gen
-                                   dict_ids exports
+                                   dict_vars exports
                                    (dict_binds `unionBags` binds')
 
   ; return ([unitBag abs_bind], poly_ids)      -- poly_ids are guaranteed zonked by mkExport
@@ -741,9 +741,9 @@ generalise dflags top_lvl bind_list sig_fn mono_infos lie_req
   where
     bndrs   = bndrNames mono_infos
     sigs    = [sig | (_, Just sig, _) <- mono_infos]
-    tau_tvs = foldr (unionVarSet . exactTyVarsOfType . getMonoType) emptyVarSet mono_infos
-               -- NB: exactTyVarsOfType; see Note [Silly type synonym] 
-               --     near defn of TcType.exactTyVarsOfType
+    get_tvs | isTopLevel top_lvl = tyVarsOfType         -- See Note [Silly type synonym] in TcType
+           | otherwise          = exactTyVarsOfType
+    tau_tvs = foldr (unionVarSet . get_tvs . getMonoType) emptyVarSet mono_infos
     is_mono_sig sig = null (sig_theta sig)
     doc = ptext SLIT("type signature(s) for") <+> pprBinders bndrs