From: simonpj@microsoft.com Date: Mon, 2 Feb 2009 16:44:50 +0000 (+0000) Subject: Improve error reporting for precedence errors X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=commitdiff_plain;h=57217f68d74c803a189942eb99eed56610ad296b Improve error reporting for precedence errors Adopt the suggestion of Trac #2993, and tidy up the reporting of precedence parsing errors somewhat. --- diff --git a/compiler/rename/RnTypes.lhs b/compiler/rename/RnTypes.lhs index 0e047fe..d5fc150 100644 --- a/compiler/rename/RnTypes.lhs +++ b/compiler/rename/RnTypes.lhs @@ -23,7 +23,7 @@ import RnEnv import TcRnMonad import RdrName import PrelNames -import TypeRep ( funTyCon ) +import TypeRep ( funTyConName ) import Name import SrcLoc import NameSet @@ -32,6 +32,7 @@ import BasicTypes ( compareFixity, funTyFixity, negateFixity, Fixity(..), FixityDirection(..) ) import Outputable import FastString +import Control.Monad ( unless ) #include "HsVersions.h" \end{code} @@ -116,7 +117,7 @@ rnHsType doc ty@(HsOpTy ty1 (L loc op) ty2) ; fix <- lookupTyFixityRn l_op' ; ty1' <- rnLHsType doc ty1 ; ty2' <- rnLHsType doc ty2 - ; mkHsOpTyRn (\t1 t2 -> HsOpTy t1 l_op' t2) (ppr op') fix ty1' ty2' } + ; mkHsOpTyRn (\t1 t2 -> HsOpTy t1 l_op' t2) op' fix ty1' ty2' } rnHsType doc (HsParTy ty) = do ty' <- rnLHsType doc ty @@ -141,7 +142,7 @@ rnHsType doc (HsFunTy ty1 ty2) = do -- when we find return :: forall m. Monad m -> forall a. a -> m a -- Check for fixity rearrangements - mkHsOpTyRn HsFunTy (ppr funTyCon) funTyFixity ty1' ty2' + mkHsOpTyRn HsFunTy funTyConName funTyFixity ty1' ty2' rnHsType doc (HsListTy ty) = do ty' <- rnLHsType doc ty @@ -270,36 +271,35 @@ by the presence of ->, which is a separate syntactic construct. --------------- -- Building (ty1 `op1` (ty21 `op2` ty22)) mkHsOpTyRn :: (LHsType Name -> LHsType Name -> HsType Name) - -> SDoc -> Fixity -> LHsType Name -> LHsType Name + -> Name -> Fixity -> LHsType Name -> LHsType Name -> RnM (HsType Name) mkHsOpTyRn mk1 pp_op1 fix1 ty1 (L loc2 (HsOpTy ty21 op2 ty22)) = do { fix2 <- lookupTyFixityRn op2 ; mk_hs_op_ty mk1 pp_op1 fix1 ty1 (\t1 t2 -> HsOpTy t1 op2 t2) - (ppr op2) fix2 ty21 ty22 loc2 } + (unLoc op2) fix2 ty21 ty22 loc2 } mkHsOpTyRn mk1 pp_op1 fix1 ty1 (L loc2 (HsFunTy ty21 ty22)) = mk_hs_op_ty mk1 pp_op1 fix1 ty1 - HsFunTy (ppr funTyCon) funTyFixity ty21 ty22 loc2 + HsFunTy funTyConName funTyFixity ty21 ty22 loc2 mkHsOpTyRn mk1 _ _ ty1 ty2 -- Default case, no rearrangment = return (mk1 ty1 ty2) --------------- mk_hs_op_ty :: (LHsType Name -> LHsType Name -> HsType Name) - -> SDoc -> Fixity -> LHsType Name + -> Name -> Fixity -> LHsType Name -> (LHsType Name -> LHsType Name -> HsType Name) - -> SDoc -> Fixity -> LHsType Name -> LHsType Name -> SrcSpan + -> Name -> Fixity -> LHsType Name -> LHsType Name -> SrcSpan -> RnM (HsType Name) -mk_hs_op_ty mk1 pp_op1 fix1 ty1 - mk2 pp_op2 fix2 ty21 ty22 loc2 - | nofix_error = do { addErr (precParseErr (quotes pp_op1,fix1) - (quotes pp_op2,fix2)) +mk_hs_op_ty mk1 op1 fix1 ty1 + mk2 op2 fix2 ty21 ty22 loc2 + | nofix_error = do { precParseErr (op1,fix1) (op2,fix2) ; return (mk1 ty1 (L loc2 (mk2 ty21 ty22))) } | associate_right = return (mk1 ty1 (L loc2 (mk2 ty21 ty22))) | otherwise = do { -- Rearrange to ((ty1 `op1` ty21) `op2` ty22) - new_ty <- mkHsOpTyRn mk1 pp_op1 fix1 ty1 ty21 + new_ty <- mkHsOpTyRn mk1 op1 fix1 ty1 ty21 ; return (mk2 (noLoc new_ty) ty22) } where (nofix_error, associate_right) = compareFixity fix1 fix2 @@ -314,9 +314,9 @@ mkOpAppRn :: LHsExpr Name -- Left operand; already rearranged -- (e11 `op1` e12) `op2` e2 mkOpAppRn e1@(L _ (OpApp e11 op1 fix1 e12)) op2 fix2 e2 - | nofix_error = do - addErr (precParseErr (ppr_op op1,fix1) (ppr_op op2,fix2)) - return (OpApp e1 op2 fix2 e2) + | nofix_error + = do precParseErr (get_op op1,fix1) (get_op op2,fix2) + return (OpApp e1 op2 fix2 e2) | associate_right = do new_e <- mkOpAppRn e12 op2 fix2 e2 @@ -328,13 +328,13 @@ mkOpAppRn e1@(L _ (OpApp e11 op1 fix1 e12)) op2 fix2 e2 --------------------------- -- (- neg_arg) `op` e2 mkOpAppRn e1@(L _ (NegApp neg_arg neg_name)) op2 fix2 e2 - | nofix_error = do - addErr (precParseErr (pp_prefix_minus,negateFixity) (ppr_op op2,fix2)) - return (OpApp e1 op2 fix2 e2) + | nofix_error + = do precParseErr (negateName,negateFixity) (get_op op2,fix2) + return (OpApp e1 op2 fix2 e2) - | associate_right = do - new_e <- mkOpAppRn neg_arg op2 fix2 e2 - return (NegApp (L loc' new_e) neg_name) + | associate_right + = do new_e <- mkOpAppRn neg_arg op2 fix2 e2 + return (NegApp (L loc' new_e) neg_name) where loc' = combineLocs neg_arg e2 (nofix_error, associate_right) = compareFixity negateFixity fix2 @@ -342,9 +342,9 @@ mkOpAppRn e1@(L _ (NegApp neg_arg neg_name)) op2 fix2 e2 --------------------------- -- e1 `op` - neg_arg mkOpAppRn e1 op1 fix1 e2@(L _ (NegApp _ _)) -- NegApp can occur on the right - | not associate_right= do -- We *want* right association - addErr (precParseErr (ppr_op op1, fix1) (pp_prefix_minus, negateFixity)) - return (OpApp e1 op1 fix1 e2) + | not associate_right -- We *want* right association + = do precParseErr (get_op op1, fix1) (negateName, negateFixity) + return (OpApp e1 op1 fix1 e2) where (_, associate_right) = compareFixity fix1 negateFixity @@ -356,6 +356,11 @@ mkOpAppRn e1 op fix e2 -- Default case, no rearrangment ) return (OpApp e1 op fix e2) +---------------------------- +get_op :: LHsExpr Name -> Name +get_op (L _ (HsVar n)) = n +get_op other = pprPanic "get_op" (ppr other) + -- Parser left-associates everything, but -- derived instances may have correctly-associated things to -- in the right operarand. So we just check that the right operand is OK @@ -387,14 +392,14 @@ mkOpFormRn :: LHsCmdTop Name -- Left operand; already rearranged -- (e11 `op1` e12) `op2` e2 mkOpFormRn a1@(L loc (HsCmdTop (L _ (HsArrForm op1 (Just fix1) [a11,a12])) _ _ _)) op2 fix2 a2 - | nofix_error = do - addErr (precParseErr (ppr_op op1,fix1) (ppr_op op2,fix2)) - return (HsArrForm op2 (Just fix2) [a1, a2]) - - | associate_right = do - new_c <- mkOpFormRn a12 op2 fix2 a2 - return (HsArrForm op1 (Just fix1) - [a11, L loc (HsCmdTop (L loc new_c) [] placeHolderType [])]) + | nofix_error + = do precParseErr (get_op op1,fix1) (get_op op2,fix2) + return (HsArrForm op2 (Just fix2) [a1, a2]) + + | associate_right + = do new_c <- mkOpFormRn a12 op2 fix2 a2 + return (HsArrForm op1 (Just fix1) + [a11, L loc (HsCmdTop (L loc new_c) [] placeHolderType [])]) -- TODO: locs are wrong where (nofix_error, associate_right) = compareFixity fix1 fix2 @@ -413,7 +418,7 @@ mkConOpPatRn op2 fix2 p1@(L loc (ConPatIn op1 (InfixCon p11 p12))) p2 ; let (nofix_error, associate_right) = compareFixity fix1 fix2 ; if nofix_error then do - { addErr (precParseErr (ppr_op op1,fix1) (ppr_op op2,fix2)) + { precParseErr (unLoc op1,fix1) (unLoc op2,fix2) ; return (ConPatIn op2 (InfixCon p1 p2)) } else if associate_right then do @@ -462,11 +467,10 @@ checkPrec op (ConPatIn op1 (InfixCon _ _)) right = do (op1_dir == InfixR && op_dir == InfixR && right || op1_dir == InfixL && op_dir == InfixL && not right)) - info = (ppr_op op, op_fix) - info1 = (ppr_op op1, op1_fix) + info = (op, op_fix) + info1 = (unLoc op1, op1_fix) (infol, infor) = if right then (info, info1) else (info1, info) - - checkErr inf_ok (precParseErr infol infor) + unless inf_ok (precParseErr infol infor) checkPrec _ _ _ = return () @@ -479,41 +483,47 @@ checkSectionPrec :: FixityDirection -> HsExpr RdrName -> LHsExpr Name -> LHsExpr Name -> RnM () checkSectionPrec direction section op arg = case unLoc arg of - OpApp _ op fix _ -> go_for_it (ppr_op op) fix - NegApp _ _ -> go_for_it pp_prefix_minus negateFixity + OpApp _ op fix _ -> go_for_it (get_op op) fix + NegApp _ _ -> go_for_it negateName negateFixity _ -> return () where - L _ (HsVar op_name) = op - go_for_it pp_arg_op arg_fix@(Fixity arg_prec assoc) = do + op_name = get_op op + go_for_it arg_op arg_fix@(Fixity arg_prec assoc) = do op_fix@(Fixity op_prec _) <- lookupFixityRn op_name - checkErr (op_prec < arg_prec - || op_prec == arg_prec && direction == assoc) - (sectionPrecErr (ppr_op op_name, op_fix) - (pp_arg_op, arg_fix) section) + unless (op_prec < arg_prec + || (op_prec == arg_prec && direction == assoc)) + (sectionPrecErr (op_name, op_fix) + (arg_op, arg_fix) section) \end{code} Precedence-related error messages \begin{code} -precParseErr :: (SDoc, Fixity) -> (SDoc, Fixity) -> SDoc -precParseErr op1 op2 - = hang (ptext (sLit "precedence parsing error")) +precParseErr :: (Name, Fixity) -> (Name, Fixity) -> RnM () +precParseErr op1@(n1,_) op2@(n2,_) + | isUnboundName n1 || isUnboundName n2 + = return () -- Avoid error cascade + | otherwise + = addErr $ hang (ptext (sLit "Precedence parsing error")) 4 (hsep [ptext (sLit "cannot mix"), ppr_opfix op1, ptext (sLit "and"), ppr_opfix op2, ptext (sLit "in the same infix expression")]) -sectionPrecErr :: (SDoc, Fixity) -> (SDoc, Fixity) -> HsExpr RdrName -> SDoc -sectionPrecErr op arg_op section - = vcat [ptext (sLit "The operator") <+> ppr_opfix op <+> ptext (sLit "of a section"), - nest 4 (ptext (sLit "must have lower precedence than the operand") <+> ppr_opfix arg_op), +sectionPrecErr :: (Name, Fixity) -> (Name, Fixity) -> HsExpr RdrName -> RnM () +sectionPrecErr op@(n1,_) arg_op@(n2,_) section + | isUnboundName n1 || isUnboundName n2 + = return () -- Avoid error cascade + | otherwise + = addErr $ vcat [ptext (sLit "The operator") <+> ppr_opfix op <+> ptext (sLit "of a section"), + nest 4 (sep [ptext (sLit "must have lower precedence than that of the operand,"), + nest 2 (ptext (sLit "namely") <+> ppr_opfix arg_op)]), nest 4 (ptext (sLit "in the section:") <+> quotes (ppr section))] -pp_prefix_minus :: SDoc -pp_prefix_minus = ptext (sLit "prefix `-'") -ppr_op :: Outputable a => a -> SDoc -ppr_op op = quotes (ppr op) -- Here, op can be a Name or a (Var n), where n is a Name -ppr_opfix :: (SDoc, Fixity) -> SDoc -ppr_opfix (pp_op, fixity) = pp_op <+> brackets (ppr fixity) +ppr_opfix :: (Name, Fixity) -> SDoc +ppr_opfix (op, fixity) = pp_op <+> brackets (ppr fixity) + where + pp_op | op == negateName = ptext (sLit "prefix `-'") + | otherwise = quotes (ppr op) \end{code} %********************************************************* diff --git a/compiler/types/TypeRep.lhs b/compiler/types/TypeRep.lhs index f71606e..600b731 100644 --- a/compiler/types/TypeRep.lhs +++ b/compiler/types/TypeRep.lhs @@ -15,7 +15,7 @@ module TypeRep ( Kind, ThetaType, -- Synonyms - funTyCon, + funTyCon, funTyConName, -- Pretty-printing pprType, pprParendType, pprTypeApp,