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 f27637d..d0044d4 100644 (file)
--- a/compiler/typecheck/TcBinds.lhs
+++ b/compiler/typecheck/TcBinds.lhs
@@ -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