Fix zonking in mkExports

I'd missed zonk, so that an error message for missing type signature
read (unhelpfully)

  main/GHC.hs:1070:0:
     Warning: Definition but no type signature for `upsweep''
              Inferred type: upsweep' :: forall t1. t

The trouble was that 't' hadn't been zonked.

Push to the stable branch

diff --git a/compiler/typecheck/TcBinds.lhs b/compiler/typecheck/TcBinds.lhs
index 671bfea..ba4bfc6 100644 (file)
--- a/compiler/typecheck/TcBinds.lhs
+++ b/compiler/typecheck/TcBinds.lhs
@@ -378,17 +378,18 @@ mkExport top_lvl prag_fn inferred_tvs dict_tys (poly_name, mb_sig, mono_id)
   = do { warn_missing_sigs <- doptM Opt_WarnMissingSigs
        ; let warn = isTopLevel top_lvl && warn_missing_sigs
        ; (tvs, poly_id) <- mk_poly_id warn mb_sig
+               -- poly_id has a zonked type
 
-       ; poly_id' <- zonkId poly_id
-       ; prags <- tcPrags poly_id' (prag_fn poly_name)
+       ; prags <- tcPrags poly_id (prag_fn poly_name)
                -- tcPrags requires a zonked poly_id
 
-       ; return (tvs, poly_id', mono_id, prags) }
+       ; return (tvs, poly_id, mono_id, prags) }
   where
     poly_ty = mkForAllTys inferred_tvs (mkFunTys dict_tys (idType mono_id))
 
-    mk_poly_id warn Nothing    = do { missingSigWarn warn poly_name poly_ty
-                                   ; return (inferred_tvs, mkLocalId poly_name poly_ty) }
+    mk_poly_id warn Nothing    = do { poly_ty' <- zonkTcType poly_ty
+                                   ; missingSigWarn warn poly_name poly_ty'
+                                   ; return (inferred_tvs, mkLocalId poly_name poly_ty') }
     mk_poly_id warn (Just sig) = do { tvs <- mapM zonk_tv (sig_tvs sig)
                                    ; return (tvs,  sig_id sig) }