Wibble to fix of Trac #5439: deal with the error-recovery case

Even if we are recovering from a typecheck error, we should still do
the right thing for the "closed" flag.  Otherwise we get an assert
failure, and potentially different behaviour when the user fixes
the original type error.

1 files changed, 4 insertions, 1 deletions

diff --git a/compiler/typecheck/TcBinds.lhs b/compiler/typecheck/TcBinds.lhs
index 0979e45eb7..3597ebf426 100644
--- a/compiler/typecheck/TcBinds.lhs
+++ b/compiler/typecheck/TcBinds.lhs
@@ -716,12 +716,15 @@ recoveryCode :: [Name] -> SigFun -> TcM (LHsBinds TcId, [Id], TopLevelFlag)
 recoveryCode binder_names sig_fn
   = do  { traceTc "tcBindsWithSigs: error recovery" (ppr binder_names)
         ; poly_ids <- mapM mk_dummy binder_names
-        ; return (emptyBag, poly_ids, TopLevel) }
+        ; return (emptyBag, poly_ids, if all is_closed poly_ids
+                                      then TopLevel else NotTopLevel) }
   where
     mk_dummy name 
         | isJust (sig_fn name) = tcLookupId name        -- Had signature; look it up
         | otherwise            = return (mkLocalId name forall_a_a)    -- No signature
 
+    is_closed poly_id = isEmptyVarSet (tyVarsOfType (idType poly_id))
+
 forall_a_a :: TcType
 forall_a_a = mkForAllTy openAlphaTyVar (mkTyVarTy openAlphaTyVar)
 \end{code}