Improve error messages for type functions

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

diff --git a/compiler/typecheck/TcExpr.lhs b/compiler/typecheck/TcExpr.lhs
index 687f3d5..b255fdb 100644 (file)
--- a/compiler/typecheck/TcExpr.lhs
+++ b/compiler/typecheck/TcExpr.lhs
@@ -809,12 +809,12 @@ tcId :: InstOrigin
      -> BoxyRhoType                            -- Result type
      -> TcM (HsExpr TcId)
 tcId orig fun_name res_ty
-  = do { (fun, fun_ty) <- lookupFun orig fun_name
-        ; traceTc (text "tcId" <+> ppr fun_name <+> (ppr fun_ty $$ ppr res_ty))
-       
+  = do { traceTc (text "tcId" <+> ppr fun_name <+> ppr res_ty)
+       ; (fun, fun_ty) <- lookupFun orig fun_name
+
        -- Split up the function type
        ; let (tv_theta_prs, fun_tau) = tcMultiSplitSigmaTy fun_ty
-             qtvs = concatMap fst tv_theta_prs         -- Quantified tyvars
+             qtvs = concatMap fst tv_theta_prs -- Quantified tyvars
              tau_qtvs = exactTyVarsOfType fun_tau      -- Mentioned in the tau part
        ; qtv_tys <- preSubType qtvs tau_qtvs fun_tau res_ty
 
@@ -822,8 +822,6 @@ tcId orig fun_name res_ty
        ; let res_subst = zipTopTvSubst qtvs qtv_tys
              fun_tau'  = substTy res_subst fun_tau
 
-        ; traceTc (text "tcId2" <+> ppr fun_name <+> (ppr qtvs $$ ppr qtv_tys))
-
        ; co_fn <- tcSubExp orig fun_tau' res_ty
 
        -- And pack up the results
@@ -1071,6 +1069,9 @@ lookupFun orig id_name
                -- nor does it need the 'lifting' treatment
 
            ATcId { tct_id = id, tct_type = ty, tct_co = mb_co, tct_level = lvl }
+               | isNaughtyRecordSelector id -> failWithTc (naughtyRecordSel id)
+                                         -- Note [Local record selectors]
+               | otherwise
                -> do { thLocalId orig id ty lvl
                      ; case mb_co of
                          Unrefineable    -> return (HsVar id, ty)
@@ -1149,6 +1150,12 @@ thBrackId orig id ps_var lie_var
 #endif /* GHCI */
 \end{code}
 
+Local record selectors
+~~~~~~~~~~~~~~~~~~~~~~
+Record selectors for TyCons in this module are ordinary local bindings,
+which show up as ATcIds rather than AGlobals.  So we need to check for
+naughtiness in both branches.  c.f. TcTyClsBindings.mkAuxBinds.
+
 
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