{-# LANGUAGE GADTs #-} {-# LANGUAGE LambdaCase #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE ViewPatterns #-} {-# LANGUAGE DataKinds #-} {-# LANGUAGE MultiWayIf #-} -- -- (c) The University of Glasgow 2002-2006 -- -- Functions over HsSyn specialised to RdrName. module GHC.Parser.PostProcess ( mkRdrGetField, mkRdrProjection, Fbind, -- RecordDot mkHsOpApp, mkHsIntegral, mkHsFractional, mkHsIsString, mkHsDo, mkMDo, mkSpliceDecl, mkRoleAnnotDecl, mkClassDecl, mkTyData, mkDataFamInst, mkTySynonym, mkTyFamInstEqn, mkStandaloneKindSig, mkTyFamInst, mkFamDecl, mkInlinePragma, mkOpaquePragma, mkPatSynMatchGroup, mkRecConstrOrUpdate, mkTyClD, mkInstD, mkRdrRecordCon, mkRdrRecordUpd, setRdrNameSpace, fromSpecTyVarBndr, fromSpecTyVarBndrs, annBinds, stmtsAnchor, stmtsLoc, cvBindGroup, cvBindsAndSigs, cvTopDecls, placeHolderPunRhs, -- Stuff to do with Foreign declarations mkImport, parseCImport, mkExport, mkExtName, -- RdrName -> CLabelString mkGadtDecl, -- [LocatedA RdrName] -> LHsType RdrName -> ConDecl RdrName mkConDeclH98, -- Bunch of functions in the parser monad for -- checking and constructing values checkImportDecl, checkExpBlockArguments, checkCmdBlockArguments, checkPrecP, -- Int -> P Int checkContext, -- HsType -> P HsContext checkPattern, -- HsExp -> P HsPat checkPattern_details, incompleteDoBlock, ParseContext(..), checkMonadComp, checkValDef, -- (SrcLoc, HsExp, HsRhs, [HsDecl]) -> P HsDecl checkValSigLhs, LRuleTyTmVar, RuleTyTmVar(..), mkRuleBndrs, mkRuleTyVarBndrs, checkRuleTyVarBndrNames, checkRecordSyntax, checkEmptyGADTs, addFatalError, hintBangPat, mkBangTy, UnpackednessPragma(..), mkMultTy, mkMultAnn, -- Token location mkTokenLocation, -- Help with processing exports ImpExpSubSpec(..), ImpExpQcSpec(..), mkModuleImpExp, mkTypeImpExp, mkImpExpSubSpec, checkImportSpec, -- Token symbols starSym, -- Warnings and errors warnStarIsType, warnPrepositiveQualifiedModule, failOpFewArgs, failNotEnabledImportQualifiedPost, failImportQualifiedTwice, SumOrTuple (..), -- Expression/command/pattern ambiguity resolution PV, runPV, ECP(ECP, unECP), DisambInfixOp(..), DisambECP(..), ecpFromExp, ecpFromCmd, ecpFromPat, ArrowParsingMode(..), withArrowParsingMode, withArrowParsingMode', setTelescopeBndrsNameSpace, PatBuilder, hsHoleExpr, -- Type/datacon ambiguity resolution DisambTD(..), addUnpackednessP, dataConBuilderCon, dataConBuilderDetails, mkUnboxedSumCon, -- ListTuplePuns related parsers mkTupleSyntaxTy, mkTupleSyntaxTycon, mkListSyntaxTy0, mkListSyntaxTy1, withCombinedComments, requireLTPuns, ) where import GHC.Prelude import GHC.Hs -- Lots of it import GHC.Core.TyCon ( TyCon, isTupleTyCon, tyConSingleDataCon_maybe ) import GHC.Core.DataCon ( DataCon, dataConTyCon, dataConName ) import GHC.Core.ConLike ( ConLike(..) ) import GHC.Core.Coercion.Axiom ( Role, fsFromRole ) import GHC.Types.Name.Reader import GHC.Types.Name import GHC.Types.Basic import GHC.Types.Error import GHC.Types.Fixity import GHC.Types.Hint import GHC.Types.SourceText import GHC.Parser.Types import GHC.Parser.Lexer import GHC.Parser.Errors.Types import GHC.Utils.Lexeme ( okConOcc ) import GHC.Types.TyThing import GHC.Core.Type ( Specificity(..) ) import GHC.Builtin.Types( cTupleTyConName, tupleTyCon, tupleDataCon, nilDataConName, nilDataConKey, listTyConName, listTyConKey, sumDataCon, unrestrictedFunTyCon , listTyCon_RDR, unitDataCon ) import GHC.Types.ForeignCall import GHC.Types.SrcLoc import GHC.Types.Unique ( hasKey ) import GHC.Data.OrdList import GHC.Utils.Outputable as Outputable import GHC.Data.FastString import GHC.Data.Maybe import GHC.Utils.Error import GHC.Utils.Misc import GHC.Utils.Monad (unlessM) import Data.Either import Data.List ( findIndex ) import Data.Foldable import qualified Data.Semigroup as Semi import GHC.Unit.Module.Warnings import GHC.Utils.Panic import qualified GHC.Data.Strict as Strict import Language.Haskell.Syntax.Basic (FieldLabelString(..)) import Control.Monad import Text.ParserCombinators.ReadP as ReadP import Data.Char import Data.Data ( dataTypeOf, fromConstr, dataTypeConstrs ) import Data.Kind ( Type ) import Data.List.NonEmpty (NonEmpty) {- ********************************************************************** Construction functions for Rdr stuff ********************************************************************* -} -- | mkClassDecl builds a RdrClassDecl, filling in the names for tycon and -- datacon by deriving them from the name of the class. We fill in the names -- for the tycon and datacon corresponding to the class, by deriving them -- from the name of the class itself. This saves recording the names in the -- interface file (which would be equally good). -- Similarly for mkConDecl, mkClassOpSig and default-method names. -- *** See Note [The Naming story] in GHC.Hs.Decls **** mkTyClD :: LTyClDecl (GhcPass p) -> LHsDecl (GhcPass p) mkTyClD (L loc d) = L loc (TyClD noExtField d) mkInstD :: LInstDecl (GhcPass p) -> LHsDecl (GhcPass p) mkInstD (L loc d) = L loc (InstD noExtField d) mkClassDecl :: SrcSpan -> Located (Maybe (LHsContext GhcPs), LHsType GhcPs) -> Located (a,[LHsFunDep GhcPs]) -> OrdList (LHsDecl GhcPs) -> EpLayout -> AnnClassDecl -> P (LTyClDecl GhcPs) mkClassDecl loc' (L _ (mcxt, tycl_hdr)) fds where_cls layout annsIn = do { (binds, sigs, ats, at_defs, _, docs) <- cvBindsAndSigs where_cls ; (cls, tparams, fixity, ops, cps, cs) <- checkTyClHdr True tycl_hdr ; tyvars <- checkTyVars (text "class") whereDots cls tparams ; let anns' = annsIn { acd_openp = ops, acd_closep = cps} ; let loc = EpAnn (spanAsAnchor loc') noAnn cs ; return (L loc (ClassDecl { tcdCExt = (anns', layout, NoAnnSortKey) , tcdCtxt = mcxt , tcdLName = cls, tcdTyVars = tyvars , tcdFixity = fixity , tcdFDs = snd (unLoc fds) , tcdSigs = mkClassOpSigs sigs , tcdMeths = binds , tcdATs = ats, tcdATDefs = at_defs , tcdDocs = docs })) } mkTyData :: SrcSpan -> Bool -> NewOrData -> Maybe (LocatedP CType) -> Located (Maybe (LHsContext GhcPs), LHsType GhcPs) -> Maybe (LHsKind GhcPs) -> [LConDecl GhcPs] -> Located (HsDeriving GhcPs) -> AnnDataDefn -> P (LTyClDecl GhcPs) mkTyData loc' is_type_data new_or_data cType (L _ (mcxt, tycl_hdr)) ksig data_cons (L _ maybe_deriv) annsIn = do { (tc, tparams, fixity, ops, cps, cs) <- checkTyClHdr False tycl_hdr ; tyvars <- checkTyVars (ppr new_or_data) equalsDots tc tparams ; let anns = annsIn {andd_openp = ops, andd_closep = cps} ; data_cons <- checkNewOrData loc' (unLoc tc) is_type_data new_or_data data_cons ; defn <- mkDataDefn cType mcxt ksig data_cons maybe_deriv anns ; !cs' <- getCommentsFor loc' ; let loc = EpAnn (spanAsAnchor loc') noAnn (cs' Semi.<> cs) ; return (L loc (DataDecl { tcdDExt = noExtField, tcdLName = tc, tcdTyVars = tyvars, tcdFixity = fixity, tcdDataDefn = defn })) } mkDataDefn :: Maybe (LocatedP CType) -> Maybe (LHsContext GhcPs) -> Maybe (LHsKind GhcPs) -> DataDefnCons (LConDecl GhcPs) -> HsDeriving GhcPs -> AnnDataDefn -> P (HsDataDefn GhcPs) mkDataDefn cType mcxt ksig data_cons maybe_deriv anns = do { checkDatatypeContext mcxt ; return (HsDataDefn { dd_ext = anns , dd_cType = cType , dd_ctxt = mcxt , dd_cons = data_cons , dd_kindSig = ksig , dd_derivs = maybe_deriv }) } mkTySynonym :: SrcSpan -> LHsType GhcPs -- LHS -> LHsType GhcPs -- RHS -> EpToken "type" -> EpToken "=" -> P (LTyClDecl GhcPs) mkTySynonym loc lhs rhs antype aneq = do { (tc, tparams, fixity, ops, cps, cs) <- checkTyClHdr False lhs ; tyvars <- checkTyVars (text "type") equalsDots tc tparams ; let anns = AnnSynDecl ops cps antype aneq ; let loc' = EpAnn (spanAsAnchor loc) noAnn cs ; return (L loc' (SynDecl { tcdSExt = anns , tcdLName = tc, tcdTyVars = tyvars , tcdFixity = fixity , tcdRhs = rhs })) } mkStandaloneKindSig :: SrcSpan -> Located [LocatedN RdrName] -- LHS -> LHsSigType GhcPs -- RHS -> (EpToken "type", TokDcolon) -> P (LStandaloneKindSig GhcPs) mkStandaloneKindSig loc lhs rhs anns = do { vs <- mapM check_lhs_name (unLoc lhs) ; v <- check_singular_lhs (reverse vs) ; return $ L (noAnnSrcSpan loc) $ StandaloneKindSig anns v rhs } where check_lhs_name v@(unLoc->name) = if isUnqual name && isTcOcc (rdrNameOcc name) then return v else addFatalError $ mkPlainErrorMsgEnvelope (getLocA v) $ (PsErrUnexpectedQualifiedConstructor (unLoc v)) check_singular_lhs vs = case vs of [] -> panic "mkStandaloneKindSig: empty left-hand side" [v] -> return v _ -> addFatalError $ mkPlainErrorMsgEnvelope (getLoc lhs) $ (PsErrMultipleNamesInStandaloneKindSignature vs) mkTyFamInstEqn :: SrcSpan -> HsOuterFamEqnTyVarBndrs GhcPs -> LHsType GhcPs -> LHsType GhcPs -> EpToken "=" -> P (LTyFamInstEqn GhcPs) mkTyFamInstEqn loc bndrs lhs rhs annEq = do { (tc, tparams, fixity, ops, cps, cs) <- checkTyClHdr False lhs ; let loc' = EpAnn (spanAsAnchor loc) noAnn cs ; return (L loc' $ FamEqn { feqn_ext = (ops, cps, annEq) , feqn_tycon = tc , feqn_bndrs = bndrs , feqn_pats = tparams , feqn_fixity = fixity , feqn_rhs = rhs })} mkDataFamInst :: SrcSpan -> NewOrData -> Maybe (LocatedP CType) -> (Maybe ( LHsContext GhcPs), HsOuterFamEqnTyVarBndrs GhcPs , LHsType GhcPs) -> Maybe (LHsKind GhcPs) -> [LConDecl GhcPs] -> Located (HsDeriving GhcPs) -> AnnDataDefn -> P (LInstDecl GhcPs) mkDataFamInst loc new_or_data cType (mcxt, bndrs, tycl_hdr) ksig data_cons (L _ maybe_deriv) anns = do { (tc, tparams, fixity, ops, cps, cs) <- checkTyClHdr False tycl_hdr ; data_cons <- checkNewOrData loc (unLoc tc) False new_or_data data_cons ; let anns' = anns {andd_openp = ops, andd_closep = cps} ; defn <- mkDataDefn cType mcxt ksig data_cons maybe_deriv anns' ; let loc' = EpAnn (spanAsAnchor loc) noAnn cs ; return (L loc' (DataFamInstD noExtField (DataFamInstDecl (FamEqn { feqn_ext = ([], [], NoEpTok) , feqn_tycon = tc , feqn_bndrs = bndrs , feqn_pats = tparams , feqn_fixity = fixity , feqn_rhs = defn })))) } mkTyFamInst :: SrcSpan -> TyFamInstEqn GhcPs -> EpToken "type" -> EpToken "instance" -> P (LInstDecl GhcPs) mkTyFamInst loc eqn t i = do return (L (noAnnSrcSpan loc) (TyFamInstD noExtField (TyFamInstDecl (t,i) eqn))) mkFamDecl :: SrcSpan -> FamilyInfo GhcPs -> TopLevelFlag -> LHsType GhcPs -- LHS -> LFamilyResultSig GhcPs -- Optional result signature -> Maybe (LInjectivityAnn GhcPs) -- Injectivity annotation -> AnnFamilyDecl -> P (LTyClDecl GhcPs) mkFamDecl loc info topLevel lhs ksig injAnn annsIn = do { (tc, tparams, fixity, ops, cps, cs) <- checkTyClHdr False lhs ; tyvars <- checkTyVars (ppr info) equals_or_where tc tparams ; let loc' = EpAnn (spanAsAnchor loc) noAnn cs ; let anns' = annsIn { afd_openp = ops, afd_closep = cps } ; return (L loc' (FamDecl noExtField (FamilyDecl { fdExt = anns' , fdTopLevel = topLevel , fdInfo = info, fdLName = tc , fdTyVars = tyvars , fdFixity = fixity , fdResultSig = ksig , fdInjectivityAnn = injAnn }))) } where equals_or_where = case info of DataFamily -> empty OpenTypeFamily -> empty ClosedTypeFamily {} -> whereDots mkSpliceDecl :: LHsExpr GhcPs -> (LHsDecl GhcPs) -- If the user wrote -- [pads| ... ] then return a QuasiQuoteD -- $(e) then return a SpliceD -- but if they wrote, say, -- f x then behave as if they'd written $(f x) -- ie a SpliceD -- -- Typed splices are not allowed at the top level, thus we do not represent them -- as spliced declaration. See #10945 mkSpliceDecl lexpr@(L loc expr) | HsUntypedSplice _ splice@(HsUntypedSpliceExpr {}) <- expr = L loc $ SpliceD noExtField (SpliceDecl noExtField (L (l2l loc) splice) DollarSplice) | HsUntypedSplice _ splice@(HsQuasiQuote {}) <- expr = L loc $ SpliceD noExtField (SpliceDecl noExtField (L (l2l loc) splice) DollarSplice) | otherwise = L loc $ SpliceD noExtField (SpliceDecl noExtField (L (l2l loc) (HsUntypedSpliceExpr noAnn (la2la lexpr))) BareSplice) mkRoleAnnotDecl :: SrcSpan -> LocatedN RdrName -- type being annotated -> [Located (Maybe FastString)] -- roles -> (EpToken "type", EpToken "role") -> P (LRoleAnnotDecl GhcPs) mkRoleAnnotDecl loc tycon roles anns = do { roles' <- mapM parse_role roles ; !cs <- getCommentsFor loc ; return $ L (EpAnn (spanAsAnchor loc) noAnn cs) $ RoleAnnotDecl anns tycon roles' } where role_data_type = dataTypeOf (undefined :: Role) all_roles = map fromConstr $ dataTypeConstrs role_data_type possible_roles = [(fsFromRole role, role) | role <- all_roles] parse_role (L loc_role Nothing) = return $ L (noAnnSrcSpan loc_role) Nothing parse_role (L loc_role (Just role)) = case lookup role possible_roles of Just found_role -> return $ L (noAnnSrcSpan loc_role) $ Just found_role Nothing -> let nearby = fuzzyLookup (unpackFS role) (mapFst unpackFS possible_roles) in addFatalError $ mkPlainErrorMsgEnvelope loc_role $ (PsErrIllegalRoleName role nearby) mkMDo :: HsDoFlavour -> LocatedLW [ExprLStmt GhcPs] -> EpaLocation -> EpaLocation -> HsExpr GhcPs mkMDo ctxt stmts tok loc = mkHsDoAnns ctxt stmts (AnnList (Just loc) ListNone [] tok []) -- | Converts a list of 'LHsTyVarBndr's annotated with their 'Specificity' to -- binders without annotations. Only accepts specified variables, and errors if -- any of the provided binders has an 'InferredSpec' annotation. fromSpecTyVarBndrs :: [LHsTyVarBndr Specificity GhcPs] -> P [LHsTyVarBndr () GhcPs] fromSpecTyVarBndrs = mapM fromSpecTyVarBndr -- | Converts 'LHsTyVarBndr' annotated with its 'Specificity' to one without -- annotations. Only accepts specified variables, and errors if the provided -- binder has an 'InferredSpec' annotation. fromSpecTyVarBndr :: LHsTyVarBndr Specificity GhcPs -> P (LHsTyVarBndr () GhcPs) fromSpecTyVarBndr (L loc (HsTvb xtv flag idp k)) = do case flag of SpecifiedSpec -> return () InferredSpec -> addFatalError $ mkPlainErrorMsgEnvelope (locA loc) $ PsErrInferredTypeVarNotAllowed return $ L loc (HsTvb xtv () idp k) -- | Add the annotation for a 'where' keyword to existing @HsLocalBinds@ annBinds :: EpToken "where" -> EpAnnComments -> HsLocalBinds GhcPs -> (HsLocalBinds GhcPs, Maybe EpAnnComments) annBinds w cs (HsValBinds an bs) = (HsValBinds (add_where w an cs) bs, Nothing) annBinds w cs (HsIPBinds an bs) = (HsIPBinds (add_where w an cs) bs, Nothing) annBinds _ cs (EmptyLocalBinds x) = (EmptyLocalBinds x, Just cs) add_where :: EpToken "where" -> EpAnn (AnnList (EpToken "where")) -> EpAnnComments -> EpAnn (AnnList (EpToken "where")) add_where w@(EpTok (EpaSpan (RealSrcSpan rs _))) (EpAnn a al cs) cs2 | valid_anchor a = EpAnn (widenAnchorT a w) (al { al_rest = w}) (cs Semi.<> cs2) | otherwise = EpAnn (patch_anchor rs a) (al { al_anchor = (fmap (patch_anchor rs) (al_anchor al)) , al_rest = w}) (cs Semi.<> cs2) add_where _ _ _ = panic "add_where" -- EpaDelta should only be used for transformations valid_anchor :: EpaLocation -> Bool valid_anchor (EpaSpan (RealSrcSpan r _)) = srcSpanStartLine r >= 0 valid_anchor _ = False -- If the decl list for where binds is empty, the anchor ends up -- invalid. In this case, use the parent one patch_anchor :: RealSrcSpan -> EpaLocation -> EpaLocation patch_anchor r EpaDelta{} = EpaSpan (RealSrcSpan r Strict.Nothing) patch_anchor r1 (EpaSpan (RealSrcSpan r0 mb)) = EpaSpan (RealSrcSpan r mb) where r = if srcSpanStartLine r0 < 0 then r1 else r0 patch_anchor _ (EpaSpan ss) = EpaSpan ss -- | The anchor for a stmtlist is based on either the location or -- the first semicolon annotion. stmtsAnchor :: Located (OrdList (EpToken tok),a) -> Maybe EpaLocation stmtsAnchor (L (RealSrcSpan l mb) ((ConsOL (EpTok (EpaSpan (RealSrcSpan r rb))) _), _)) = Just $ widenAnchorS (EpaSpan (RealSrcSpan l mb)) (RealSrcSpan r rb) stmtsAnchor (L (RealSrcSpan l mb) _) = Just $ EpaSpan (RealSrcSpan l mb) stmtsAnchor _ = Nothing stmtsLoc :: Located (OrdList (EpToken tok),a) -> SrcSpan stmtsLoc (L l ((ConsOL aa _), _)) = widenSpanT l aa stmtsLoc (L l _) = l {- ********************************************************************** #cvBinds-etc# Converting to @HsBinds@, etc. ********************************************************************* -} -- | Function definitions are restructured here. Each is assumed to be recursive -- initially, and non recursive definitions are discovered by the dependency -- analyser. -- | Groups together bindings for a single function cvTopDecls :: OrdList (LHsDecl GhcPs) -> [LHsDecl GhcPs] cvTopDecls decls = getMonoBindAll (fromOL decls) -- Declaration list may only contain value bindings and signatures. cvBindGroup :: OrdList (LHsDecl GhcPs) -> P (HsValBinds GhcPs) cvBindGroup binding = do { (mbs, sigs, fam_ds, tfam_insts , dfam_insts, _) <- cvBindsAndSigs binding ; massert (null fam_ds && null tfam_insts && null dfam_insts) ; return $ ValBinds NoAnnSortKey mbs sigs } cvBindsAndSigs :: OrdList (LHsDecl GhcPs) -> P (LHsBinds GhcPs, [LSig GhcPs], [LFamilyDecl GhcPs] , [LTyFamInstDecl GhcPs], [LDataFamInstDecl GhcPs], [LDocDecl GhcPs]) -- Input decls contain just value bindings and signatures -- and in case of class or instance declarations also -- associated type declarations. They might also contain Haddock comments. cvBindsAndSigs fb = do fb' <- drop_bad_decls (fromOL fb) return (partitionBindsAndSigs (getMonoBindAll fb')) where -- cvBindsAndSigs is called in several places in the parser, -- and its items can be produced by various productions: -- -- * decl (when parsing a where clause or a let-expression) -- * decl_inst (when parsing an instance declaration) -- * decl_cls (when parsing a class declaration) -- -- partitionBindsAndSigs can handle almost all declaration forms produced -- by the aforementioned productions, except for SpliceD, which we filter -- out here (in drop_bad_decls). -- -- We're not concerned with every declaration form possible, such as those -- produced by the topdecl parser production, because cvBindsAndSigs is not -- called on top-level declarations. drop_bad_decls [] = return [] drop_bad_decls (L l (SpliceD _ d) : ds) = do addError $ mkPlainErrorMsgEnvelope (locA l) $ PsErrDeclSpliceNotAtTopLevel d drop_bad_decls ds drop_bad_decls (d:ds) = (d:) <$> drop_bad_decls ds ----------------------------------------------------------------------------- -- Group function bindings into equation groups getMonoBind :: LHsBind GhcPs -> [LHsDecl GhcPs] -> (LHsBind GhcPs, [LHsDecl GhcPs]) -- Suppose (b',ds') = getMonoBind b ds -- ds is a list of parsed bindings -- b is a MonoBinds that has just been read off the front -- Then b' is the result of grouping more equations from ds that -- belong with b into a single MonoBinds, and ds' is the depleted -- list of parsed bindings. -- -- All Haddock comments between equations inside the group are -- discarded. -- -- No AndMonoBinds or EmptyMonoBinds here; just single equations getMonoBind (L loc1 (FunBind { fun_id = fun_id1@(L _ f1) , fun_matches = MG { mg_alts = (L _ m1@[L _ mtchs1]) } })) binds | has_args m1 = go [L loc1 mtchs1] (noAnnSrcSpan $ locA loc1) binds [] where -- See Note [Exact Print Annotations for FunBind] go :: [LMatch GhcPs (LHsExpr GhcPs)] -- accumulates matches for current fun -> SrcSpanAnnA -- current top level loc -> [LHsDecl GhcPs] -- Any docbinds seen -> [LHsDecl GhcPs] -- rest of decls to be processed -> (LHsBind GhcPs, [LHsDecl GhcPs]) -- FunBind, rest of decls go mtchs loc ((L loc2 (ValD _ (FunBind { fun_id = (L _ f2) , fun_matches = MG { mg_alts = (L _ [L lm2 mtchs2]) } }))) : binds) _ | f1 == f2 = let (loc2', lm2') = transferAnnsA loc2 lm2 in go (L lm2' mtchs2 : mtchs) (combineSrcSpansA loc loc2') binds [] go mtchs loc (doc_decl@(L loc2 (DocD {})) : binds) doc_decls = let doc_decls' = doc_decl : doc_decls in go mtchs (combineSrcSpansA loc loc2) binds doc_decls' go mtchs loc binds doc_decls = let L llm last_m = head mtchs -- Guaranteed at least one (llm',loc') = transferAnnsOnlyA llm loc -- Keep comments, transfer trailing matches' = reverse (L llm' last_m:tail mtchs) L lfm first_m = head matches' (lfm', loc'') = transferCommentsOnlyA lfm loc' in ( L loc'' (makeFunBind fun_id1 (mkLocatedList $ (L lfm' first_m:tail matches'))) , (reverse doc_decls) ++ binds) -- Reverse the final matches, to get it back in the right order -- Do the same thing with the trailing doc comments getMonoBind bind binds = (bind, binds) {- Note [Exact Print Annotations for FunBind] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ An individual Match that ends up in a FunBind MatchGroup is initially parsed as a LHsDecl. This takes the form L loc (ValD NoExtField (FunBind ... [L lm (Match ..)])) The loc contains the annotations, in particular comments, which are to precede the declaration when printed, and [TrailingAnn] which are to follow it. The [TrailingAnn] captures semicolons that may appear after it when using the braces and semis style of coding. The match location (lm) has only a location in it at this point, no annotations. Its location is the same as the top level location in loc. What getMonoBind does it to take a sequence of FunBind LHsDecls that belong to the same function and group them into a single function with the component declarations all combined into the single MatchGroup as [LMatch GhcPs]. Given that when exact printing a FunBind the exact printer simply iterates over all the matches and prints each in turn, the simplest behaviour would be to simply take the top level annotations (loc) for each declaration, and use them for the individual component matches (lm). The problem is the exact printer first has to deal with the top level LHsDecl, which means annotations for the loc. This needs to be able to be exact printed in the context of surrounding declarations, and if some refactor decides to move the declaration elsewhere, the leading comments and trailing semicolons need to be handled at that level. So the solution is to combine all the matches into one, pushing the annotations into the LMatch's, and then at the end extract the comments from the first match and [TrailingAnn] from the last to go in the top level LHsDecl. -} -- Group together adjacent FunBinds for every function. getMonoBindAll :: [LHsDecl GhcPs] -> [LHsDecl GhcPs] getMonoBindAll [] = [] getMonoBindAll (L l (ValD _ b) : ds) = let (L l' b', ds') = getMonoBind (L l b) ds in L l' (ValD noExtField b') : getMonoBindAll ds' getMonoBindAll (d : ds) = d : getMonoBindAll ds has_args :: [LMatch GhcPs (LHsExpr GhcPs)] -> Bool has_args [] = panic "GHC.Parser.PostProcess.has_args" has_args (L _ (Match { m_pats = L _ args }) : _) = not (null args) -- Don't group together FunBinds if they have -- no arguments. This is necessary now that variable bindings -- with no arguments are now treated as FunBinds rather -- than pattern bindings (tests/rename/should_fail/rnfail002). {- ********************************************************************** #PrefixToHS-utils# Utilities for conversion ********************************************************************* -} {- Note [Parsing data constructors is hard] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The problem with parsing data constructors is that they look a lot like types. Compare: (s1) data T = C t1 t2 (s2) type T = C t1 t2 Syntactically, there's little difference between these declarations, except in (s1) 'C' is a data constructor, but in (s2) 'C' is a type constructor. This similarity would pose no problem if we knew ahead of time if we are parsing a type or a constructor declaration. Looking at (s1) and (s2), a simple (but wrong!) rule comes to mind: in 'data' declarations assume we are parsing data constructors, and in other contexts (e.g. 'type' declarations) assume we are parsing type constructors. This simple rule does not work because of two problematic cases: (p1) data T = C t1 t2 :+ t3 (p2) data T = C t1 t2 => t3 In (p1) we encounter (:+) and it turns out we are parsing an infix data declaration, so (C t1 t2) is a type and 'C' is a type constructor. In (p2) we encounter (=>) and it turns out we are parsing an existential context, so (C t1 t2) is a constraint and 'C' is a type constructor. As the result, in order to determine whether (C t1 t2) declares a data constructor, a type, or a context, we would need unlimited lookahead which 'happy' is not so happy with. -} -- | Reinterpret a type constructor, including type operators, as a data -- constructor. -- See Note [Parsing data constructors is hard] tyConToDataCon :: LocatedN RdrName -> Either (MsgEnvelope PsMessage) (LocatedN RdrName) tyConToDataCon (L loc tc) | okConOcc (occNameString occ) = return (L loc (setRdrNameSpace tc srcDataName)) | otherwise = Left $ mkPlainErrorMsgEnvelope (locA loc) $ (PsErrNotADataCon tc) where occ = rdrNameOcc tc mkPatSynMatchGroup :: LocatedN RdrName -> LocatedLW (OrdList (LHsDecl GhcPs)) -> P (MatchGroup GhcPs (LHsExpr GhcPs)) mkPatSynMatchGroup (L loc patsyn_name) (L ld decls) = do { matches <- mapM fromDecl (fromOL decls) ; when (null matches) (wrongNumberErr (locA loc)) ; return $ mkMatchGroup FromSource (L ld matches) } where fromDecl (L loc decl@(ValD _ (PatBind _ pat@(L _ (ConPat _conAnn ln@(L _ name) details)) _ rhs))) = do { unless (name == patsyn_name) $ wrongNameBindingErr (locA loc) decl -- conAnn should only be AnnOpenP, AnnCloseP, so the rest should be empty ; let ann_fun = mk_ann_funrhs [] [] ; match <- case details of PrefixCon _ pats -> return $ Match { m_ext = noExtField , m_ctxt = ctxt, m_pats = L l pats , m_grhss = rhs } where l = listLocation pats ctxt = FunRhs { mc_fun = ln , mc_fixity = Prefix , mc_strictness = NoSrcStrict , mc_an = ann_fun } InfixCon p1 p2 -> return $ Match { m_ext = noExtField , m_ctxt = ctxt , m_pats = L l [p1, p2] , m_grhss = rhs } where l = listLocation [p1, p2] ctxt = FunRhs { mc_fun = ln , mc_fixity = Infix , mc_strictness = NoSrcStrict , mc_an = ann_fun } RecCon{} -> recordPatSynErr (locA loc) pat ; return $ L loc match } fromDecl (L loc decl) = extraDeclErr (locA loc) decl extraDeclErr loc decl = addFatalError $ mkPlainErrorMsgEnvelope loc $ (PsErrNoSingleWhereBindInPatSynDecl patsyn_name decl) wrongNameBindingErr loc decl = addFatalError $ mkPlainErrorMsgEnvelope loc $ (PsErrInvalidWhereBindInPatSynDecl patsyn_name decl) wrongNumberErr loc = addFatalError $ mkPlainErrorMsgEnvelope loc $ (PsErrEmptyWhereInPatSynDecl patsyn_name) recordPatSynErr :: SrcSpan -> LPat GhcPs -> P a recordPatSynErr loc pat = addFatalError $ mkPlainErrorMsgEnvelope loc $ (PsErrRecordSyntaxInPatSynDecl pat) mkConDeclH98 :: (TokDarrow, (TokForall, EpToken ".")) -> LocatedN RdrName -> Maybe [LHsTyVarBndr Specificity GhcPs] -> Maybe (LHsContext GhcPs) -> HsConDeclH98Details GhcPs -> ConDecl GhcPs mkConDeclH98 (tdarrow, (tforall,tdot)) name mb_forall mb_cxt args = ConDeclH98 { con_ext = AnnConDeclH98 tforall tdot tdarrow , con_name = name , con_forall = isJust mb_forall , con_ex_tvs = mb_forall `orElse` [] , con_mb_cxt = mb_cxt , con_args = args , con_doc = Nothing } -- | Construct a GADT-style data constructor from the constructor names and -- their type. Some interesting aspects of this function: -- -- * This splits up the constructor type into its quantified type variables (if -- provided), context (if provided), argument types, and result type, and -- records whether this is a prefix or record GADT constructor. See -- Note [GADT abstract syntax] in "GHC.Hs.Decls" for more details. mkGadtDecl :: SrcSpan -> NonEmpty (LocatedN RdrName) -> TokDcolon -> LHsSigType GhcPs -> P (LConDecl GhcPs) mkGadtDecl loc names dcol ty = do (args, res_ty, (ops, cps), csa) <- case body_ty of L ll (HsFunTy _ hsArr (L (EpAnn anc _ cs) (HsRecTy an rf)) res_ty) -> do arr <- case hsArr of HsUnrestrictedArrow arr -> return arr _ -> do addError $ mkPlainErrorMsgEnvelope (getLocA body_ty) $ (PsErrIllegalGadtRecordMultiplicity hsArr) return noAnn return ( RecConGADT arr (L (EpAnn anc an cs) rf), res_ty , ([], []), epAnnComments ll) _ -> do let ((ops, cps), cs, arg_types, res_type) = splitHsFunType body_ty return (PrefixConGADT noExtField arg_types, res_type, (ops,cps), cs) let bndrs_loc = case outer_bndrs of HsOuterImplicit{} -> getLoc ty HsOuterExplicit an _ -> EpAnn (entry an) noAnn emptyComments let l = EpAnn (spanAsAnchor loc) noAnn csa pure $ L l ConDeclGADT { con_g_ext = AnnConDeclGADT ops cps dcol , con_names = names , con_bndrs = L bndrs_loc outer_bndrs , con_mb_cxt = mcxt , con_g_args = args , con_res_ty = res_ty , con_doc = Nothing } where (outer_bndrs, mcxt, body_ty) = splitLHsGadtTy ty setRdrNameSpace :: RdrName -> NameSpace -> RdrName -- ^ This rather gruesome function is used mainly by the parser. -- -- Case #1. When parsing: -- -- > data T a = T | T1 Int -- -- we parse the data constructors as /types/ because of parser ambiguities, -- so then we need to change the /type constr/ to a /data constr/ -- -- The exact-name case /can/ occur when parsing: -- -- > data [] a = [] | a : [a] -- -- For the exact-name case we return an original name. -- -- Case #2. When parsing: -- -- > x = fn (forall a. a) -- RequiredTypeArguments -- -- we use setRdrNameSpace to set the namespace of forall-bound variables. -- setRdrNameSpace (Unqual occ) ns = Unqual (setOccNameSpace ns occ) setRdrNameSpace (Qual m occ) ns = Qual m (setOccNameSpace ns occ) setRdrNameSpace (Orig m occ) ns = Orig m (setOccNameSpace ns occ) setRdrNameSpace (Exact n) ns | Just thing <- wiredInNameTyThing_maybe n = setWiredInNameSpace thing ns -- Preserve Exact Names for wired-in things, -- notably tuples and lists | isExternalName n = Orig (nameModule n) occ | otherwise -- This can happen when quoting and then -- splicing a fixity declaration for a type = Exact (mkSystemNameAt (nameUnique n) occ (nameSrcSpan n)) where occ = setOccNameSpace ns (nameOccName n) setWiredInNameSpace :: TyThing -> NameSpace -> RdrName setWiredInNameSpace (ATyCon tc) ns | isDataConNameSpace ns = ty_con_data_con tc | isTcClsNameSpace ns = Exact (getName tc) -- No-op setWiredInNameSpace (AConLike (RealDataCon dc)) ns | isTcClsNameSpace ns = data_con_ty_con dc | isDataConNameSpace ns = Exact (getName dc) -- No-op setWiredInNameSpace thing ns = pprPanic "setWiredinNameSpace" (pprNameSpace ns <+> ppr thing) ty_con_data_con :: TyCon -> RdrName ty_con_data_con tc | isTupleTyCon tc , Just dc <- tyConSingleDataCon_maybe tc = Exact (getName dc) | tc `hasKey` listTyConKey = Exact nilDataConName | otherwise -- See Note [setRdrNameSpace for wired-in names] = Unqual (setOccNameSpace srcDataName (getOccName tc)) data_con_ty_con :: DataCon -> RdrName data_con_ty_con dc | let tc = dataConTyCon dc , isTupleTyCon tc = Exact (getName tc) | dc `hasKey` nilDataConKey = Exact listTyConName | otherwise -- See Note [setRdrNameSpace for wired-in names] = Unqual (setOccNameSpace tcClsName (getOccName dc)) {- Note [setRdrNameSpace for wired-in names] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In GHC.Types, which declares (:), we have infixr 5 : The ambiguity about which ":" is meant is resolved by parsing it as a data constructor, but then using dataTcOccs to try the type constructor too; and that in turn calls setRdrNameSpace to change the name-space of ":" to tcClsName. There isn't a corresponding ":" type constructor, but it's painful to make setRdrNameSpace partial, so we just make an Unqual name instead. It really doesn't matter! -} eitherToP :: MonadP m => Either (MsgEnvelope PsMessage) a -> m a -- Adapts the Either monad to the P monad eitherToP (Left err) = addFatalError err eitherToP (Right thing) = return thing checkTyVars :: SDoc -> SDoc -> LocatedN RdrName -> [LHsTypeArg GhcPs] -> P (LHsQTyVars GhcPs) -- the synthesized type variables -- ^ Check whether the given list of type parameters are all type variables -- (possibly with a kind signature). checkTyVars pp_what equals_or_where tc tparms = do { tvs <- mapM check tparms ; return (mkHsQTvs tvs) } where check (HsTypeArg at ki) = chkParens [] [] (HsBndrInvisible at) ki check (HsValArg _ ty) = chkParens [] [] (HsBndrRequired noExtField) ty check (HsArgPar sp) = addFatalError $ mkPlainErrorMsgEnvelope sp $ (PsErrMalformedDecl pp_what (unLoc tc)) -- Keep around an action for adjusting the annotations of extra parens chkParens :: [EpaLocation] -> [EpaLocation] -> HsBndrVis GhcPs -> LHsType GhcPs -> P (LHsTyVarBndr (HsBndrVis GhcPs) GhcPs) chkParens ops cps bvis (L l (HsParTy _ (L lt ty))) = let (o,c) = mkParensLocs (realSrcSpan $ locA l) (_,lt') = transferCommentsOnlyA l lt in chkParens (o:ops) (c:cps) bvis (L lt' ty) chkParens ops cps bvis ty = chk ops cps bvis ty -- Check that the name space is correct! chk :: [EpaLocation] -> [EpaLocation] -> HsBndrVis GhcPs -> LHsType GhcPs -> P (LHsTyVarBndr (HsBndrVis GhcPs) GhcPs) chk ops cps bvis (L l (HsKindSig tok_dc (L annt t) k)) | Just (ann, bvar) <- match_bndr_var t = let bkind = HsBndrKind noExtField k an = (reverse ops) ++ cps in return (L (widenLocatedAnL (l Semi.<> annt) (for_widening bvis:an)) (HsTvb (AnnTyVarBndr (reverse ops) cps ann tok_dc) bvis bvar bkind)) chk ops cps bvis (L l t) | Just (ann, bvar) <- match_bndr_var t = let bkind = HsBndrNoKind noExtField an = (reverse ops) ++ cps in return (L (widenLocatedAnL l (for_widening bvis:an)) (HsTvb (AnnTyVarBndr (reverse ops) cps ann noAnn) bvis bvar bkind)) chk _ _ _ t@(L loc _) = addFatalError $ mkPlainErrorMsgEnvelope (locA loc) $ (PsErrUnexpectedTypeInDecl t pp_what (unLoc tc) tparms equals_or_where) match_bndr_var :: HsType GhcPs -> Maybe (EpToken "'", HsBndrVar GhcPs) match_bndr_var (HsTyVar ann _ tv) | isRdrTyVar (unLoc tv) = Just (ann, HsBndrVar noExtField tv) match_bndr_var (HsWildCardTy tok) = Just (noAnn, HsBndrWildCard tok) match_bndr_var _ = Nothing -- Return a EpaLocation for use in widenLocatedAnL. for_widening :: HsBndrVis GhcPs -> EpaLocation for_widening (HsBndrInvisible (EpTok loc)) = loc for_widening _ = noAnn whereDots, equalsDots :: SDoc -- Second argument to checkTyVars whereDots = text "where ..." equalsDots = text "= ..." checkDatatypeContext :: Maybe (LHsContext GhcPs) -> P () checkDatatypeContext Nothing = return () checkDatatypeContext (Just c) = do allowed <- getBit DatatypeContextsBit unless allowed $ addError $ mkPlainErrorMsgEnvelope (getLocA c) $ (PsErrIllegalDataTypeContext c) type LRuleTyTmVar = LocatedAn NoEpAnns RuleTyTmVar data RuleTyTmVar = RuleTyTmVar AnnTyVarBndr (LocatedN RdrName) (Maybe (LHsType GhcPs)) -- ^ Essentially a wrapper for a @RuleBndr GhcPs@ -- turns RuleTyTmVars into RuleBnrs - this is straightforward mkRuleBndrs :: [LRuleTyTmVar] -> [LRuleBndr GhcPs] mkRuleBndrs = fmap (fmap cvt_one) where cvt_one (RuleTyTmVar ann v Nothing) = RuleBndr ann v cvt_one (RuleTyTmVar ann v (Just sig)) = RuleBndrSig ann v (mkHsPatSigType noAnn sig) -- turns RuleTyTmVars into HsTyVarBndrs - this is more interesting mkRuleTyVarBndrs :: [LRuleTyTmVar] -> [LHsTyVarBndr () GhcPs] mkRuleTyVarBndrs = fmap (setLHsTyVarBndrNameSpace tvName . cvt_one) where cvt_one (L l (RuleTyTmVar ann v msig)) = L (l2l l) (HsTvb ann () (HsBndrVar noExtField v) (cvt_sig msig)) cvt_sig Nothing = HsBndrNoKind noExtField cvt_sig (Just sig) = HsBndrKind noExtField sig -- See Note [Parsing explicit foralls in Rules] in Parser.y checkRuleTyVarBndrNames :: [LHsTyVarBndr flag GhcPs] -> P () checkRuleTyVarBndrNames = mapM_ check . mapMaybe (hsTyVarLName . unLoc) where check (L loc (Unqual occ)) = when (occNameFS occ `elem` [fsLit "family",fsLit "role"]) (addFatalError $ mkPlainErrorMsgEnvelope (locA loc) $ (PsErrParseErrorOnInput occ)) check _ = panic "checkRuleTyVarBndrNames" checkRecordSyntax :: (MonadP m, Outputable a) => LocatedA a -> m (LocatedA a) checkRecordSyntax lr@(L loc r) = do allowed <- getBit TraditionalRecordSyntaxBit unless allowed $ addError $ mkPlainErrorMsgEnvelope (locA loc) $ (PsErrIllegalTraditionalRecordSyntax (ppr r)) return lr -- | Check if the gadt_constrlist is empty. Only raise parse error for -- `data T where` to avoid affecting existing error message, see #8258. checkEmptyGADTs :: Located ((EpToken "where", EpToken "{", EpToken "}"), [LConDecl GhcPs]) -> P (Located ((EpToken "where", EpToken "{", EpToken "}"), [LConDecl GhcPs])) checkEmptyGADTs gadts@(L span (_, [])) -- Empty GADT declaration. = do gadtSyntax <- getBit GadtSyntaxBit -- GADTs implies GADTSyntax unless gadtSyntax $ addError $ mkPlainErrorMsgEnvelope span $ PsErrIllegalWhereInDataDecl return gadts checkEmptyGADTs gadts = return gadts -- Ordinary GADT declaration. checkTyClHdr :: Bool -- True <=> class header -- False <=> type header -> LHsType GhcPs -> P (LocatedN RdrName, -- the head symbol (type or class name) [LHsTypeArg GhcPs], -- parameters of head symbol LexicalFixity, -- the declaration is in infix format [EpToken "("], -- API Annotation for HsParTy [EpToken ")"], -- when stripping parens EpAnnComments) -- Accumulated comments from re-arranging -- Well-formedness check and decomposition of type and class heads. -- Decomposes T ty1 .. tyn into (T, [ty1, ..., tyn]) -- Int :*: Bool into (:*:, [Int, Bool]) -- returning the pieces checkTyClHdr is_cls ty = goL emptyComments ty [] [] [] Prefix where goL cs (L l ty) acc ops cps fix = go cs l ty acc ops cps fix -- workaround to define '*' despite StarIsType go cs ll (HsParTy an (L l (HsStarTy _ isUni))) acc ops' cps' fix = do { addPsMessage (locA l) PsWarnStarBinder ; let name = mkOccNameFS tcClsName (starSym isUni) ; let a' = newAnns ll l an ; return (L a' (Unqual name), acc, fix , (reverse ops'), cps', cs) } go cs l (HsTyVar _ _ ltc@(L _ tc)) acc ops cps fix | isRdrTc tc = return (ltc, acc, fix, (reverse ops), cps, cs Semi.<> comments l) go cs l (HsOpTy _ _ t1 ltc@(L _ tc) t2) acc ops cps _fix | isRdrTc tc = return (ltc, lhs:rhs:acc, Infix, (reverse ops), cps, cs Semi.<> comments l) where lhs = HsValArg noExtField t1 rhs = HsValArg noExtField t2 go cs l (HsParTy (o,c) ty) acc ops cps fix = goL (cs Semi.<> comments l) ty acc (o:ops) (c:cps) fix go cs l (HsAppTy _ t1 t2) acc ops cps fix = goL (cs Semi.<> comments l) t1 (HsValArg noExtField t2:acc) ops cps fix go cs l (HsAppKindTy at ty ki) acc ops cps fix = goL (cs Semi.<> comments l) ty (HsTypeArg at ki:acc) ops cps fix go cs l (HsTupleTy _ HsBoxedOrConstraintTuple ts) [] ops cps fix = return (L (l2l l) (nameRdrName tup_name) , map (HsValArg noExtField) ts, fix, (reverse ops), cps, cs Semi.<> comments l) where arity = length ts tup_name | is_cls = cTupleTyConName arity | otherwise = getName (tupleTyCon Boxed arity) -- See Note [Unit tuples] in GHC.Hs.Type (TODO: is this still relevant?) go _ l _ _ _ _ _ = addFatalError $ mkPlainErrorMsgEnvelope (locA l) $ (PsErrMalformedTyOrClDecl ty) -- Combine the annotations from the HsParTy and HsStarTy into a -- new one for the LocatedN RdrName newAnns :: SrcSpanAnnA -> SrcSpanAnnA -> (EpToken "(", EpToken ")") -> SrcSpanAnnN newAnns l@(EpAnn _ (AnnListItem _) csp0) l1@(EpAnn ap (AnnListItem ta) csp) (o,c) = let lr = combineSrcSpans (locA l1) (locA l) in EpAnn (EpaSpan lr) (NameAnn (NameParens o c) ap ta) (csp0 Semi.<> csp) -- | Yield a parse error if we have a function applied directly to a do block -- etc. and BlockArguments is not enabled. checkExpBlockArguments :: LHsExpr GhcPs -> PV () checkCmdBlockArguments :: LHsCmd GhcPs -> PV () (checkExpBlockArguments, checkCmdBlockArguments) = (checkExpr, checkCmd) where checkExpr :: LHsExpr GhcPs -> PV () checkExpr expr = case unLoc expr of HsDo _ (DoExpr m) _ -> check (PsErrDoInFunAppExpr m) expr HsDo _ (MDoExpr m) _ -> check (PsErrMDoInFunAppExpr m) expr HsCase {} -> check PsErrCaseInFunAppExpr expr HsLam _ lam_variant _ -> check (PsErrLambdaInFunAppExpr lam_variant) expr HsLet {} -> check PsErrLetInFunAppExpr expr HsIf {} -> check PsErrIfInFunAppExpr expr HsProc {} -> check PsErrProcInFunAppExpr expr _ -> return () checkCmd :: LHsCmd GhcPs -> PV () checkCmd cmd = case unLoc cmd of HsCmdLam _ lam_variant _ -> check (PsErrLambdaCmdInFunAppCmd lam_variant) cmd HsCmdCase {} -> check PsErrCaseCmdInFunAppCmd cmd HsCmdIf {} -> check PsErrIfCmdInFunAppCmd cmd HsCmdLet {} -> check PsErrLetCmdInFunAppCmd cmd HsCmdDo {} -> check PsErrDoCmdInFunAppCmd cmd _ -> return () check err a = do blockArguments <- getBit BlockArgumentsBit unless blockArguments $ addError $ mkPlainErrorMsgEnvelope (getLocA a) $ (err a) -- | Validate the context constraints and break up a context into a list -- of predicates. -- -- @ -- (Eq a, Ord b) --> [Eq a, Ord b] -- Eq a --> [Eq a] -- (Eq a) --> [Eq a] -- (((Eq a))) --> [Eq a] -- @ checkContext :: LHsType GhcPs -> P (LHsContext GhcPs) checkContext orig_t@(L (EpAnn l _ cs) _orig_t) = check ([],[],cs) orig_t where check :: ([EpToken "("],[EpToken ")"],EpAnnComments) -> LHsType GhcPs -> P (LHsContext GhcPs) check (oparens,cparens,cs) (L _l (HsTupleTy (AnnParens o c) HsBoxedOrConstraintTuple ts)) -- (Eq a, Ord b) shows up as a tuple type. Only boxed tuples can -- be used as context constraints. -- Ditto () = mkCTuple (oparens ++ [o], c : cparens, cs) ts -- With NoListTuplePuns, contexts are parsed as data constructors, which causes failure -- downstream. -- This converts them just like when they are parsed as types in the punned case. check (oparens,cparens,cs) (L _l (HsExplicitTupleTy (q,o,c) _ ts)) = punsAllowed >>= \case True -> unprocessed False -> do let (op, cp) = case q of EpTok ql -> ([EpTok ql], [c]) _ -> ([o], [c]) mkCTuple (oparens ++ op, cp ++ cparens, cs) ts check (opi,cpi,csi) (L _lp1 (HsParTy (o,c) ty)) -- to be sure HsParTy doesn't get into the way = check (o:opi, c:cpi, csi) ty -- No need for anns, returning original check (_opi,_cpi,_csi) _t = unprocessed unprocessed = return (L (EpAnn l (AnnContext Nothing [] []) emptyComments) [orig_t]) mkCTuple (oparens, cparens, cs) ts = -- Append parens so that the original order in the source is maintained return (L (EpAnn l (AnnContext Nothing oparens cparens) cs) ts) -- | The same as `checkContext`, but for expressions. -- -- Validate the context constraints and break up a context into a list -- of predicates. -- -- @ -- (Eq a, Ord b) --> [Eq a, Ord b] -- Eq a --> [Eq a] -- (Eq a) --> [Eq a] -- (((Eq a))) --> [Eq a] -- @ checkContextExpr :: LHsExpr GhcPs -> PV (LocatedC [LHsExpr GhcPs]) checkContextExpr orig_expr@(L (EpAnn l _ cs) _) = check ([],[], cs) orig_expr where check :: ([EpToken "("],[EpToken ")"],EpAnnComments) -> LHsExpr GhcPs -> PV (LocatedC [LHsExpr GhcPs]) check (oparens,cparens,cs) (L _ (ExplicitTuple (ap_open, ap_close) tup_args boxity)) -- Neither unboxed tuples (#e1,e2#) nor tuple sections (e1,,e2,) can be a context | isBoxed boxity , Just es <- tupArgsPresent_maybe tup_args = mkCTuple (oparens ++ [EpTok ap_open], EpTok ap_close : cparens, cs) es check (opi, cpi, csi) (L _ (HsPar (open_tok, close_tok) expr)) = check (opi ++ [open_tok], close_tok : cpi, csi) expr check (oparens,cparens,cs) (L _ (HsVar _ (L (EpAnn _ (NameAnnOnly (NameParens open closed) []) _) name))) | name == nameRdrName (dataConName unitDataCon) = mkCTuple (oparens ++ [open], closed : cparens, cs) [] check _ _ = unprocessed unprocessed = return (L (EpAnn l (AnnContext Nothing [] []) emptyComments) [orig_expr]) mkCTuple (oparens, cparens, cs) ts = -- Append parens so that the original order in the source is maintained return (L (EpAnn l (AnnContext Nothing oparens cparens) cs) ts) checkImportDecl :: Maybe (EpToken "qualified") -> Maybe (EpToken "qualified") -> P () checkImportDecl mPre mPost = do let whenJust mg f = maybe (pure ()) f mg tokenSpan tok = RealSrcSpan (epaLocationRealSrcSpan $ getEpTokenLoc tok) Strict.Nothing importQualifiedPostEnabled <- getBit ImportQualifiedPostBit -- Error if 'qualified' found in postpositive position and -- 'ImportQualifiedPost' is not in effect. whenJust mPost $ \post -> when (not importQualifiedPostEnabled) $ failNotEnabledImportQualifiedPost (tokenSpan post) -- Error if 'qualified' occurs in both pre and postpositive -- positions. whenJust mPost $ \post -> when (isJust mPre) $ failImportQualifiedTwice (tokenSpan post) -- Warn if 'qualified' found in prepositive position and -- 'Opt_WarnPrepositiveQualifiedModule' is enabled. whenJust mPre $ \pre -> warnPrepositiveQualifiedModule (tokenSpan pre) -- ------------------------------------------------------------------------- -- Checking Patterns. -- We parse patterns as expressions and check for valid patterns below, -- converting the expression into a pattern at the same time. checkPattern :: LocatedA (PatBuilder GhcPs) -> P (LPat GhcPs) checkPattern = runPV . checkLPat checkPattern_details :: ParseContext -> PV (LocatedA (PatBuilder GhcPs)) -> P (LPat GhcPs) checkPattern_details extraDetails pp = runPV_details extraDetails (pp >>= checkLPat) checkLArgPat :: LocatedA (ArgPatBuilder GhcPs) -> PV (LPat GhcPs) checkLArgPat (L l (ArgPatBuilderVisPat p)) = checkLPat (L l p) checkLArgPat (L l (ArgPatBuilderArgPat p)) = return (L l p) checkLPat :: LocatedA (PatBuilder GhcPs) -> PV (LPat GhcPs) checkLPat (L l@(EpAnn anc an _) p) = do (L l' p', cs) <- checkPat (EpAnn anc an emptyComments) emptyComments (L l p) [] [] return (L (addCommentsToEpAnn l' cs) p') checkPat :: SrcSpanAnnA -> EpAnnComments -> LocatedA (PatBuilder GhcPs) -> [HsConPatTyArg GhcPs] -> [LPat GhcPs] -> PV (LPat GhcPs, EpAnnComments) -- SG: I think this function checks what Haskell2010 calls the `pat` and `lpat` -- productions checkPat loc cs (L l e@(PatBuilderVar (L ln c))) tyargs args | isRdrDataCon c || isRdrTc c = return (L loc $ ConPat { pat_con_ext = noAnn -- AZ: where should this come from? , pat_con = L ln c , pat_args = PrefixCon tyargs args }, comments l Semi.<> cs) | (not (null args) && patIsRec c) = do ctx <- askParseContext patFail (locA l) . PsErrInPat e $ PEIP_RecPattern args YesPatIsRecursive ctx checkPat loc cs (L la (PatBuilderAppType f at t)) tyargs args = checkPat loc (cs Semi.<> comments la) f (HsConPatTyArg at t : tyargs) args checkPat loc cs (L la (PatBuilderApp f e)) [] args = do p <- checkLPat e checkPat loc (cs Semi.<> comments la) f [] (p : args) checkPat loc cs (L l e) [] [] = do p <- checkAPat loc e return (L l p, cs) checkPat loc _ e _ _ = do details <- fromParseContext <$> askParseContext patFail (locA loc) (PsErrInPat (unLoc e) details) checkAPat :: SrcSpanAnnA -> PatBuilder GhcPs -> PV (Pat GhcPs) checkAPat loc e0 = do nPlusKPatterns <- getBit NPlusKPatternsBit case e0 of PatBuilderPat p -> return p PatBuilderVar x -> return (VarPat noExtField x) -- Overloaded numeric patterns (e.g. f 0 x = x) -- Negation is recorded separately, so that the literal is zero or +ve -- NB. Negative *primitive* literals are already handled by the lexer PatBuilderOverLit pos_lit -> return (mkNPat (L (l2l loc) pos_lit) Nothing noAnn) -- n+k patterns PatBuilderOpApp (L _ (PatBuilderVar (L nloc n))) (L l plus) (L lloc (PatBuilderOverLit lit@(OverLit {ol_val = HsIntegral {}}))) _ | nPlusKPatterns && (plus == plus_RDR) -> return (mkNPlusKPat (L nloc n) (L (l2l lloc) lit) (EpTok $ entry l)) -- Improve error messages for the @-operator when the user meant an @-pattern PatBuilderOpApp _ op _ _ | opIsAt (unLoc op) -> do addError $ mkPlainErrorMsgEnvelope (getLocA op) PsErrAtInPatPos return (WildPat noExtField) PatBuilderOpApp l (L cl c) r (_os,_cs) | isRdrDataCon c || isRdrTc c -> do l <- checkLPat l r <- checkLPat r return $ ConPat { pat_con_ext = noAnn , pat_con = L cl c , pat_args = InfixCon l r } PatBuilderPar lpar e rpar -> do p <- checkLPat e return (ParPat (lpar, rpar) p) _ -> do details <- fromParseContext <$> askParseContext patFail (locA loc) (PsErrInPat e0 details) placeHolderPunRhs :: DisambECP b => PV (LocatedA b) -- The RHS of a punned record field will be filled in by the renamer -- It's better not to make it an error, in case we want to print it when -- debugging placeHolderPunRhs = mkHsVarPV (noLocA pun_RDR) plus_RDR, pun_RDR :: RdrName plus_RDR = mkUnqual varName (fsLit "+") -- Hack pun_RDR = mkUnqual varName (fsLit "pun-right-hand-side") checkPatField :: LHsRecField GhcPs (LocatedA (PatBuilder GhcPs)) -> PV (LHsRecField GhcPs (LPat GhcPs)) checkPatField (L l fld) = do p <- checkLPat (hfbRHS fld) return (L l (fld { hfbRHS = p })) patFail :: SrcSpan -> PsMessage -> PV a patFail loc msg = addFatalError $ mkPlainErrorMsgEnvelope loc $ msg patIsRec :: RdrName -> Bool patIsRec e = e == mkUnqual varName (fsLit "rec") --------------------------------------------------------------------------- -- Check Equation Syntax checkValDef :: SrcSpan -> LocatedA (PatBuilder GhcPs) -> (HsMultAnn GhcPs, Maybe (TokDcolon, LHsType GhcPs)) -> Located (GRHSs GhcPs (LHsExpr GhcPs)) -> P (HsBind GhcPs) checkValDef loc lhs (mult, Just (sigAnn, sig)) grhss -- x :: ty = rhs parses as a *pattern* binding = do lhs' <- runPV $ mkHsTySigPV (combineLocsA lhs sig) lhs sig sigAnn >>= checkLPat checkPatBind loc lhs' grhss mult checkValDef loc lhs (mult_ann, Nothing) grhss | HsNoMultAnn{} <- mult_ann = do { mb_fun <- isFunLhs lhs ; case mb_fun of Just (fun, is_infix, pats, ops, cps) -> do let ann_fun = mk_ann_funrhs ops cps let l = listLocation pats checkFunBind loc ann_fun fun is_infix (L l pats) grhss Nothing -> do lhs' <- checkPattern lhs checkPatBind loc lhs' grhss mult_ann } checkValDef loc lhs (mult_ann, Nothing) ghrss -- %p x = rhs parses as a *pattern* binding = do lhs' <- checkPattern lhs checkPatBind loc lhs' ghrss mult_ann mk_ann_funrhs :: [EpToken "("] -> [EpToken ")"] -> AnnFunRhs mk_ann_funrhs ops cps = AnnFunRhs NoEpTok ops cps checkFunBind :: SrcSpan -> AnnFunRhs -> LocatedN RdrName -> LexicalFixity -> LocatedE [LocatedA (ArgPatBuilder GhcPs)] -> Located (GRHSs GhcPs (LHsExpr GhcPs)) -> P (HsBind GhcPs) checkFunBind locF ann_fun (L lf fun) is_infix (L lp pats) (L _ grhss) = do ps <- runPV_details extraDetails (mapM checkLArgPat pats) let match_span = noAnnSrcSpan $ locF return (makeFunBind (L (l2l lf) fun) (L (noAnnSrcSpan $ locA match_span) [L match_span (Match { m_ext = noExtField , m_ctxt = FunRhs { mc_fun = L lf fun , mc_fixity = is_infix , mc_strictness = NoSrcStrict , mc_an = ann_fun } , m_pats = L lp ps , m_grhss = grhss })])) -- The span of the match covers the entire equation. -- That isn't quite right, but it'll do for now. where extraDetails | Infix <- is_infix = ParseContext (Just fun) NoIncompleteDoBlock | otherwise = noParseContext makeFunBind :: LocatedN RdrName -> LocatedLW [LMatch GhcPs (LHsExpr GhcPs)] -> HsBind GhcPs -- Like GHC.Hs.Utils.mkFunBind, but we need to be able to set the fixity too makeFunBind fn ms = FunBind { fun_ext = noExtField, fun_id = fn, fun_matches = mkMatchGroup FromSource ms } -- See Note [FunBind vs PatBind] checkPatBind :: SrcSpan -> LPat GhcPs -> Located (GRHSs GhcPs (LHsExpr GhcPs)) -> HsMultAnn GhcPs -> P (HsBind GhcPs) checkPatBind loc (L _ (BangPat an (L _ (VarPat _ v)))) (L _match_span grhss) (HsNoMultAnn _) = return (makeFunBind v (L (noAnnSrcSpan loc) [L (noAnnSrcSpan loc) (m an v)])) where m a v = Match { m_ext = noExtField , m_ctxt = FunRhs { mc_fun = v , mc_fixity = Prefix , mc_strictness = SrcStrict , mc_an = AnnFunRhs a [] [] } , m_pats = noLocA [] , m_grhss = grhss } checkPatBind _loc lhs (L _ grhss) mult = do return (PatBind noExtField lhs mult grhss) checkValSigLhs :: LHsExpr GhcPs -> P (LocatedN RdrName) checkValSigLhs lhs@(L l lhs_expr) = case lhs_expr of HsVar _ lrdr@(L _ v) -> check_var v lrdr _ -> make_err PsErrInvalidTypeSig_Other where check_var v lrdr | not (isUnqual v) = make_err PsErrInvalidTypeSig_Qualified | isDataOcc occ_n = make_err PsErrInvalidTypeSig_DataCon | otherwise = pure lrdr where occ_n = rdrNameOcc v make_err reason = addFatalError $ mkPlainErrorMsgEnvelope (locA l) (PsErrInvalidTypeSignature reason lhs) checkDoAndIfThenElse :: (Outputable a, Outputable b, Outputable c) => (a -> Bool -> b -> Bool -> c -> PsMessage) -> LocatedA a -> Bool -> LocatedA b -> Bool -> LocatedA c -> PV () checkDoAndIfThenElse err guardExpr semiThen thenExpr semiElse elseExpr | semiThen || semiElse = do doAndIfThenElse <- getBit DoAndIfThenElseBit let e = err (unLoc guardExpr) semiThen (unLoc thenExpr) semiElse (unLoc elseExpr) loc = combineLocs (reLoc guardExpr) (reLoc elseExpr) unless doAndIfThenElse $ addError (mkPlainErrorMsgEnvelope loc e) | otherwise = return () isFunLhs :: LocatedA (PatBuilder GhcPs) -> P (Maybe (LocatedN RdrName, LexicalFixity, [LocatedA (ArgPatBuilder GhcPs)],[EpToken "("],[EpToken ")"])) -- A variable binding is parsed as a FunBind. -- Just (fun, is_infix, arg_pats) if e is a function LHS isFunLhs e = go e [] [] [] where mk = fmap ArgPatBuilderVisPat go (L l (PatBuilderVar (L loc f))) es ops cps | not (isRdrDataCon f) = do let (_l, loc') = transferCommentsOnlyA l loc return (Just (L loc' f, Prefix, es, (reverse ops), cps)) go (L l (PatBuilderApp (L lf f) e)) es ops cps = do let (_l, lf') = transferCommentsOnlyA l lf go (L lf' f) (mk e:es) ops cps go (L l (PatBuilderPar _ (L le e) _)) es@(_:_) ops cps = go (L le' e) es (o:ops) (c:cps) -- NB: es@(_:_) means that there must be an arg after the parens for the -- LHS to be a function LHS. This corresponds to the Haskell Report's definition -- of funlhs. where (_l, le') = transferCommentsOnlyA l le (o,c) = mkParensEpToks (realSrcSpan $ locA l) go (L loc (PatBuilderOpApp (L ll l) (L loc' op) r (os,cs))) es ops cps | not (isRdrDataCon op) -- We have found the function! = do { let (_l, ll') = transferCommentsOnlyA loc ll ; return (Just (L loc' op, Infix, (mk (L ll' l):mk r:es), (os ++ reverse ops), (cs ++ cps))) } | otherwise -- Infix data con; keep going = do { let (_l, ll') = transferCommentsOnlyA loc ll ; mb_l <- go (L ll' l) es ops cps ; return (reassociate =<< mb_l) } where reassociate (op', Infix, j : L k_loc (ArgPatBuilderVisPat k) : es', ops', cps') = Just (op', Infix, j : op_app : es', ops', cps') where op_app = mk $ L loc (PatBuilderOpApp (L k_loc k) (L loc' op) r (reverse ops, cps)) reassociate _other = Nothing go (L l (PatBuilderAppType (L lp pat) tok ty_pat@(HsTP _ (L (EpAnn anc ann cs) _)))) es ops cps = go (L lp' pat) (L (EpAnn anc' ann cs) (ArgPatBuilderArgPat invis_pat) : es) ops cps where invis_pat = InvisPat (tok, SpecifiedSpec) ty_pat anc' = widenAnchorT anc tok (_l, lp') = transferCommentsOnlyA l lp go _ _ _ _ = return Nothing data ArgPatBuilder p = ArgPatBuilderVisPat (PatBuilder p) | ArgPatBuilderArgPat (Pat p) instance Outputable (ArgPatBuilder GhcPs) where ppr (ArgPatBuilderVisPat p) = ppr p ppr (ArgPatBuilderArgPat p) = ppr p mkBangTy :: EpaLocation -> SrcStrictness -> LHsType GhcPs -> HsType GhcPs mkBangTy tok_loc strictness = HsBangTy ((noAnn, noAnn, tok_loc), NoSourceText) (HsBang NoSrcUnpack strictness) -- | Result of parsing @{-\# UNPACK \#-}@ or @{-\# NOUNPACK \#-}@. data UnpackednessPragma = UnpackednessPragma (EpaLocation, EpToken "#-}") SourceText SrcUnpackedness -- | Annotate a type with either an @{-\# UNPACK \#-}@ or a @{-\# NOUNPACK \#-}@ pragma. addUnpackednessP :: MonadP m => Located UnpackednessPragma -> LHsType GhcPs -> m (LHsType GhcPs) addUnpackednessP (L lprag (UnpackednessPragma anns prag unpk)) ty = do let l' = combineSrcSpans lprag (getLocA ty) let t' = addUnpackedness anns ty return (L (noAnnSrcSpan l') t') where -- If we have a HsBangTy that only has a strictness annotation, -- such as ~T or !T, then add the pragma to the existing HsBangTy. -- -- Otherwise, wrap the type in a new HsBangTy constructor. addUnpackedness (o,c) (L _ (HsBangTy ((_,_,tl), NoSourceText) bang t)) | HsBang NoSrcUnpack strictness <- bang = HsBangTy ((o,c,tl), prag) (HsBang unpk strictness) t addUnpackedness (o,c) t = HsBangTy ((o,c,noAnn), prag) (HsBang unpk NoSrcStrict) t --------------------------------------------------------------------------- -- | Check for monad comprehensions -- -- If the flag MonadComprehensions is set, return a 'MonadComp' context, -- otherwise use the usual 'ListComp' context checkMonadComp :: PV HsDoFlavour checkMonadComp = do monadComprehensions <- getBit MonadComprehensionsBit return $ if monadComprehensions then MonadComp else ListComp -- ------------------------------------------------------------------------- -- Expression/command/pattern ambiguity. -- See Note [Ambiguous syntactic categories] -- -- See Note [Ambiguous syntactic categories] -- -- This newtype is required to avoid impredicative types in monadic -- productions. That is, in a production that looks like -- -- | ... {% return (ECP ...) } -- -- we are dealing with -- P ECP -- whereas without a newtype we would be dealing with -- P (forall b. DisambECP b => PV (Located b)) -- newtype ECP = ECP { unECP :: forall b. DisambECP b => PV (LocatedA b) } ecpFromExp :: LHsExpr GhcPs -> ECP ecpFromExp a = ECP (ecpFromExp' a) ecpFromCmd :: LHsCmd GhcPs -> ECP ecpFromCmd a = ECP (ecpFromCmd' a) ecpFromPat :: LPat GhcPs -> ECP ecpFromPat a = ECP (ecpFromPat' a) -- The 'fbinds' parser rule produces values of this type. See Note -- [RecordDotSyntax field updates]. type Fbind b = Either (LHsRecField GhcPs (LocatedA b)) (LHsRecProj GhcPs (LocatedA b)) -- | Disambiguate infix operators. -- See Note [Ambiguous syntactic categories] class DisambInfixOp b where mkHsVarOpPV :: LocatedN RdrName -> PV (LocatedN b) mkHsConOpPV :: LocatedN RdrName -> PV (LocatedN b) mkHsInfixHolePV :: LocatedN (HsExpr GhcPs) -> PV (LocatedN b) instance DisambInfixOp (HsExpr GhcPs) where mkHsVarOpPV v = return $ L (getLoc v) (HsVar noExtField v) mkHsConOpPV v = return $ L (getLoc v) (HsVar noExtField v) mkHsInfixHolePV h = return h instance DisambInfixOp RdrName where mkHsConOpPV (L l v) = return $ L l v mkHsVarOpPV (L l v) = return $ L l v mkHsInfixHolePV (L l _) = addFatalError $ mkPlainErrorMsgEnvelope (getHasLoc l) $ PsErrInvalidInfixHole type AnnoBody b = ( Anno (GRHS GhcPs (LocatedA (Body b GhcPs))) ~ EpAnnCO , Anno [LocatedA (Match GhcPs (LocatedA (Body b GhcPs)))] ~ SrcSpanAnnLW , Anno (Match GhcPs (LocatedA (Body b GhcPs))) ~ SrcSpanAnnA , Anno (StmtLR GhcPs GhcPs (LocatedA (Body (Body b GhcPs) GhcPs))) ~ SrcSpanAnnA , Anno [LocatedA (StmtLR GhcPs GhcPs (LocatedA (Body (Body (Body b GhcPs) GhcPs) GhcPs)))] ~ SrcSpanAnnLW ) -- | Disambiguate constructs that may appear when we do not know ahead of time whether we are -- parsing an expression, a command, or a pattern. -- See Note [Ambiguous syntactic categories] class (b ~ (Body b) GhcPs, AnnoBody b) => DisambECP b where -- | See Note [Body in DisambECP] type Body b :: Type -> Type -- | Return a command without ambiguity, or fail in a non-command context. ecpFromCmd' :: LHsCmd GhcPs -> PV (LocatedA b) -- | Return an expression without ambiguity, or fail in a non-expression context. ecpFromExp' :: LHsExpr GhcPs -> PV (LocatedA b) -- | Return a pattern without ambiguity, or fail in a non-pattern context. ecpFromPat' :: LPat GhcPs -> PV (LocatedA b) mkHsProjUpdatePV :: SrcSpan -> Located [LocatedAn NoEpAnns (DotFieldOcc GhcPs)] -> LocatedA b -> Bool -> Maybe (EpToken "=") -> PV (LHsRecProj GhcPs (LocatedA b)) -- | Disambiguate "let ... in ..." mkHsLetPV :: SrcSpan -> EpToken "let" -> HsLocalBinds GhcPs -> EpToken "in" -> LocatedA b -> PV (LocatedA b) -- | Infix operator representation type InfixOp b -- | Bring superclass constraints on InfixOp into scope. -- See Note [UndecidableSuperClasses for associated types] superInfixOp :: (DisambInfixOp (InfixOp b) => PV (LocatedA b )) -> PV (LocatedA b) -- | Disambiguate "f # x" (infix operator) mkHsOpAppPV :: SrcSpan -> LocatedA b -> LocatedN (InfixOp b) -> LocatedA b -> PV (LocatedA b) -- | Disambiguate "case ... of ..." mkHsCasePV :: SrcSpan -> LHsExpr GhcPs -> (LocatedLW [LMatch GhcPs (LocatedA b)]) -> EpAnnHsCase -> PV (LocatedA b) -- | Disambiguate "\... -> ..." (lambda), "\case" and "\cases" mkHsLamPV :: SrcSpan -> HsLamVariant -> (LocatedLW [LMatch GhcPs (LocatedA b)]) -> EpAnnLam -> PV (LocatedA b) -- | Function argument representation type FunArg b -- | Bring superclass constraints on FunArg into scope. -- See Note [UndecidableSuperClasses for associated types] superFunArg :: (DisambECP (FunArg b) => PV (LocatedA b)) -> PV (LocatedA b) -- | Disambiguate "f x" (function application) mkHsAppPV :: SrcSpanAnnA -> LocatedA b -> LocatedA (FunArg b) -> PV (LocatedA b) -- | Disambiguate "f @t" (visible type application) mkHsAppTypePV :: SrcSpanAnnA -> LocatedA b -> EpToken "@" -> LHsType GhcPs -> PV (LocatedA b) -- | Disambiguate "if ... then ... else ..." mkHsIfPV :: SrcSpan -> LHsExpr GhcPs -> Bool -- semicolon? -> LocatedA b -> Bool -- semicolon? -> LocatedA b -> AnnsIf -> PV (LocatedA b) -- | Disambiguate "do { ... }" (do notation) mkHsDoPV :: SrcSpan -> Maybe ModuleName -> LocatedLW [LStmt GhcPs (LocatedA b)] -> EpaLocation -> -- Token EpaLocation -> -- Anchor PV (LocatedA b) -- | Disambiguate "( ... )" (parentheses) mkHsParPV :: SrcSpan -> EpToken "(" -> LocatedA b -> EpToken ")" -> PV (LocatedA b) -- | Disambiguate a variable "f" or a data constructor "MkF". mkHsVarPV :: LocatedN RdrName -> PV (LocatedA b) -- | Disambiguate a monomorphic literal mkHsLitPV :: Located (HsLit GhcPs) -> PV (LocatedA b) -- | Disambiguate an overloaded literal mkHsOverLitPV :: LocatedAn a (HsOverLit GhcPs) -> PV (LocatedAn a b) -- | Disambiguate a wildcard mkHsWildCardPV :: (NoAnn a) => SrcSpan -> PV (LocatedAn a b) -- | Disambiguate "a :: t" (type annotation) mkHsTySigPV :: SrcSpanAnnA -> LocatedA b -> LHsType GhcPs -> TokDcolon -> PV (LocatedA b) -- | Disambiguate "[a,b,c]" (list syntax) mkHsExplicitListPV :: SrcSpan -> [LocatedA b] -> AnnList () -> PV (LocatedA b) -- | Disambiguate "$(...)" and "[quasi|...|]" (TH splices) mkHsSplicePV :: Located (HsUntypedSplice GhcPs) -> PV (LocatedA b) -- | Disambiguate "f { a = b, ... }" syntax (record construction and record updates) mkHsRecordPV :: Bool -> -- Is OverloadedRecordUpdate in effect? SrcSpan -> SrcSpan -> LocatedA b -> ([Fbind b], Maybe SrcSpan) -> (Maybe (EpToken "{"), Maybe (EpToken "}")) -> PV (LocatedA b) -- | Disambiguate "-a" (negation) mkHsNegAppPV :: SrcSpan -> LocatedA b -> EpToken "-" -> PV (LocatedA b) -- | Disambiguate "(# a)" (right operator section) mkHsSectionR_PV :: SrcSpan -> LocatedA (InfixOp b) -> LocatedA b -> PV (LocatedA b) -- | Disambiguate "(a -> b)" (view pattern or function type arrow) mkHsArrowPV :: SrcSpan -> ArrowParsingMode lhs b -> LocatedA lhs -> HsArrowOf (LocatedA b) GhcPs -> LocatedA b -> PV (LocatedA b) -- | Disambiguate "%m" to the left of "->" (multiplicity) mkHsMultPV :: EpToken "%" -> LocatedA b -> PV (TokRarrow -> HsArrowOf (LocatedA b) GhcPs) -- | Disambiguate "forall a. b" and "forall a -> b" (forall telescope) mkHsForallPV :: SrcSpan -> HsForAllTelescope GhcPs -> LocatedA b -> PV (LocatedA b) -- | Disambiguate "(a,b,c)" to the left of "=>" (constraint list) checkContextPV :: LocatedA b -> PV (LocatedC [LocatedA b]) -- | Disambiguate "a => b" (constraint context) mkQualPV :: SrcSpan -> LocatedC [LocatedA b] -> LocatedA b -> PV (LocatedA b) -- | Disambiguate "a@b" (as-pattern) mkHsAsPatPV :: SrcSpan -> LocatedN RdrName -> EpToken "@" -> LocatedA b -> PV (LocatedA b) -- | Disambiguate "~a" (lazy pattern) mkHsLazyPatPV :: SrcSpan -> LocatedA b -> EpToken "~" -> PV (LocatedA b) -- | Disambiguate "!a" (bang pattern) mkHsBangPatPV :: SrcSpan -> LocatedA b -> EpToken "!" -> PV (LocatedA b) -- | Disambiguate tuple sections and unboxed sums mkSumOrTuplePV :: SrcSpanAnnA -> Boxity -> SumOrTuple b -> (EpaLocation, EpaLocation) -> PV (LocatedA b) -- | Disambiguate "type t" (embedded type) mkHsEmbTyPV :: SrcSpan -> EpToken "type" -> LHsType GhcPs -> PV (LocatedA b) -- | Validate infixexp LHS to reject unwanted {-# SCC ... #-} pragmas rejectPragmaPV :: LocatedA b -> PV () {- Note [UndecidableSuperClasses for associated types] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ (This Note is about the code in GHC, not about the user code that we are parsing) Assume we have a class C with an associated type T: class C a where type T a ... If we want to add 'C (T a)' as a superclass, we need -XUndecidableSuperClasses: {-# LANGUAGE UndecidableSuperClasses #-} class C (T a) => C a where type T a ... Unfortunately, -XUndecidableSuperClasses don't work all that well, sometimes making GHC loop. The workaround is to bring this constraint into scope manually with a helper method: class C a where type T a superT :: (C (T a) => r) -> r In order to avoid ambiguous types, 'r' must mention 'a'. For consistency, we use this approach for all constraints on associated types, even when -XUndecidableSuperClasses are not required. -} {- Note [Body in DisambECP] ~~~~~~~~~~~~~~~~~~~~~~~~~~~ There are helper functions (mkBodyStmt, mkBindStmt, unguardedRHS, etc) that require their argument to take a form of (body GhcPs) for some (body :: Type -> *). To satisfy this requirement, we say that (b ~ Body b GhcPs) in the superclass constraints of DisambECP. The alternative is to change mkBodyStmt, mkBindStmt, unguardedRHS, etc, to drop this requirement. It is possible and would allow removing the type index of PatBuilder, but leads to worse type inference, breaking some code in the typechecker. -} instance DisambECP (HsCmd GhcPs) where type Body (HsCmd GhcPs) = HsCmd ecpFromCmd' = return ecpFromExp' (L l e) = cmdFail (locA l) (ppr e) ecpFromPat' (L l p) = cmdFail (locA l) (ppr p) mkHsProjUpdatePV l _ _ _ _ = addFatalError $ mkPlainErrorMsgEnvelope l $ PsErrOverloadedRecordDotInvalid mkHsLamPV l lam_variant (L lm m) anns = do !cs <- getCommentsFor l let mg = mkLamCaseMatchGroup FromSource lam_variant (L lm m) return $ L (EpAnn (spanAsAnchor l) noAnn cs) (HsCmdLam anns lam_variant mg) mkHsLetPV l tkLet bs tkIn e = do !cs <- getCommentsFor l return $ L (EpAnn (spanAsAnchor l) noAnn cs) (HsCmdLet (tkLet, tkIn) bs e) type InfixOp (HsCmd GhcPs) = HsExpr GhcPs superInfixOp m = m mkHsOpAppPV l c1 op c2 = do let cmdArg c = L (l2l $ getLoc c) $ HsCmdTop noExtField c !cs <- getCommentsFor l return $ L (EpAnn (spanAsAnchor l) noAnn cs) $ HsCmdArrForm noAnn (reLoc op) Infix [cmdArg c1, cmdArg c2] mkHsCasePV l c (L lm m) anns = do !cs <- getCommentsFor l let mg = mkMatchGroup FromSource (L lm m) return $ L (EpAnn (spanAsAnchor l) noAnn cs) (HsCmdCase anns c mg) type FunArg (HsCmd GhcPs) = HsExpr GhcPs superFunArg m = m mkHsAppPV l c e = do checkCmdBlockArguments c checkExpBlockArguments e return $ L l (HsCmdApp noExtField c e) mkHsAppTypePV l c _ t = cmdFail (locA l) (ppr c <+> text "@" <> ppr t) mkHsIfPV l c semi1 a semi2 b anns = do checkDoAndIfThenElse PsErrSemiColonsInCondCmd c semi1 a semi2 b !cs <- getCommentsFor l return $ L (EpAnn (spanAsAnchor l) noAnn cs) (mkHsCmdIf c a b anns) mkHsDoPV l Nothing stmts tok_loc anc = do !cs <- getCommentsFor l return $ L (EpAnn (spanAsAnchor l) noAnn cs) (HsCmdDo (AnnList (Just anc) ListNone [] tok_loc []) stmts) mkHsDoPV l (Just m) _ _ _ = addFatalError $ mkPlainErrorMsgEnvelope l $ PsErrQualifiedDoInCmd m mkHsParPV l lpar c rpar = do !cs <- getCommentsFor l return $ L (EpAnn (spanAsAnchor l) noAnn cs) (HsCmdPar (lpar, rpar) c) mkHsVarPV (L l v) = cmdFail (locA l) (ppr v) mkHsLitPV (L l a) = cmdFail l (ppr a) mkHsOverLitPV (L l a) = cmdFail (locA l) (ppr a) mkHsWildCardPV l = cmdFail l (text "_") mkHsTySigPV l a sig _ = cmdFail (locA l) (ppr a <+> text "::" <+> ppr sig) mkHsExplicitListPV l xs _ = cmdFail l $ brackets (pprWithCommas ppr xs) mkHsSplicePV (L l sp) = cmdFail l (pprUntypedSplice True Nothing sp) mkHsRecordPV _ l _ a (fbinds, ddLoc) _ = do let (fs, ps) = partitionEithers fbinds if not (null ps) then addFatalError $ mkPlainErrorMsgEnvelope l $ PsErrOverloadedRecordDotInvalid else cmdFail l $ ppr a <+> ppr (mk_rec_fields fs ddLoc) mkHsNegAppPV l a _ = cmdFail l (text "-" <> ppr a) mkHsSectionR_PV l op c = cmdFail l $ let pp_op = fromMaybe (panic "cannot print infix operator") (ppr_infix_expr (unLoc op)) in pp_op <> ppr c mkHsArrowPV l mode a arr b = cmdFail l $ case mode of -- matching on the mode brings Outputable instances into scope ArrowIsViewPat -> ppr a <+> pprHsArrow arr <+> ppr b ArrowIsFunType -> ppr a <+> pprHsArrow arr <+> ppr b mkHsMultPV pct mult = cmdFail l $ ppr pct <> ppr mult where l = getHasLoc pct `combineSrcSpans` getHasLoc mult mkHsForallPV l tele cmd = cmdFail l $ pprHsForAll tele Nothing <+> ppr cmd checkContextPV ctxt = cmdFail (getLocA ctxt) $ ppr ctxt mkQualPV l ctxt cmd = cmdFail l $ ppr ctxt <+> text "=>" <+> ppr cmd mkHsAsPatPV l v _ c = cmdFail l $ pprPrefixOcc (unLoc v) <> text "@" <> ppr c mkHsLazyPatPV l c _ = cmdFail l $ text "~" <> ppr c mkHsBangPatPV l c _ = cmdFail l $ text "!" <> ppr c mkSumOrTuplePV l boxity a _ = cmdFail (locA l) (pprSumOrTuple boxity a) mkHsEmbTyPV l _ ty = cmdFail l (text "type" <+> ppr ty) rejectPragmaPV _ = return () cmdFail :: SrcSpan -> SDoc -> PV a cmdFail loc e = addFatalError $ mkPlainErrorMsgEnvelope loc $ PsErrParseErrorInCmd e checkLamMatchGroup :: SrcSpan -> HsLamVariant -> MatchGroup GhcPs (LHsExpr GhcPs) -> PV () checkLamMatchGroup l LamSingle (MG { mg_alts = (L _ (matches:_))}) = do when (null (hsLMatchPats matches)) $ addError $ mkPlainErrorMsgEnvelope l PsErrEmptyLambda checkLamMatchGroup _ _ _ = return () instance DisambECP (HsExpr GhcPs) where type Body (HsExpr GhcPs) = HsExpr ecpFromCmd' (L l c) = do addError $ mkPlainErrorMsgEnvelope (locA l) $ PsErrArrowCmdInExpr c return (L l (hsHoleExpr noAnn)) ecpFromExp' = return ecpFromPat' p@(L l _) = do addError $ mkPlainErrorMsgEnvelope (locA l) $ PsErrOrPatInExpr p return (L l (hsHoleExpr noAnn)) mkHsProjUpdatePV l fields arg isPun anns = do !cs <- getCommentsFor l return $ mkRdrProjUpdate (EpAnn (spanAsAnchor l) noAnn cs) fields arg isPun anns mkHsLetPV l tkLet bs tkIn c = do !cs <- getCommentsFor l return $ L (EpAnn (spanAsAnchor l) noAnn cs) (HsLet (tkLet, tkIn) bs c) type InfixOp (HsExpr GhcPs) = HsExpr GhcPs superInfixOp m = m mkHsOpAppPV l e1 op e2 = do !cs <- getCommentsFor l return $ L (EpAnn (spanAsAnchor l) noAnn cs) $ OpApp noExtField e1 (reLoc op) e2 mkHsCasePV l e (L lm m) anns = do !cs <- getCommentsFor l let mg = mkMatchGroup FromSource (L lm m) return $ L (EpAnn (spanAsAnchor l) noAnn cs) (HsCase anns e mg) mkHsLamPV l lam_variant (L lm m) anns = do !cs <- getCommentsFor l let mg = mkLamCaseMatchGroup FromSource lam_variant (L lm m) checkLamMatchGroup l lam_variant mg return $ L (EpAnn (spanAsAnchor l) noAnn cs) (HsLam anns lam_variant mg) type FunArg (HsExpr GhcPs) = HsExpr GhcPs superFunArg m = m mkHsAppPV l e1 e2 = do checkExpBlockArguments e1 checkExpBlockArguments e2 return $ L l (HsApp noExtField e1 e2) mkHsAppTypePV l e at t = do checkExpBlockArguments e return $ L l (HsAppType at e (mkHsWildCardBndrs t)) mkHsIfPV l c semi1 a semi2 b anns = do checkDoAndIfThenElse PsErrSemiColonsInCondExpr c semi1 a semi2 b !cs <- getCommentsFor l return $ L (EpAnn (spanAsAnchor l) noAnn cs) (mkHsIf c a b anns) mkHsDoPV l mod stmts loc_tok anc = do !cs <- getCommentsFor l return $ L (EpAnn (spanAsAnchor l) noAnn cs) (HsDo (AnnList (Just anc) ListNone [] loc_tok []) (DoExpr mod) stmts) mkHsParPV l lpar e rpar = do !cs <- getCommentsFor l return $ L (EpAnn (spanAsAnchor l) noAnn cs) (HsPar (lpar, rpar) e) mkHsVarPV v@(L l@(EpAnn anc _ _) _) = do !cs <- getCommentsFor (getHasLoc l) return $ L (EpAnn anc noAnn cs) (HsVar noExtField v) mkHsLitPV (L l a) = do !cs <- getCommentsFor l return $ L (EpAnn (spanAsAnchor l) noAnn cs) (HsLit noExtField a) mkHsOverLitPV (L (EpAnn l an csIn) a) = do !cs <- getCommentsFor (locA l) return $ L (EpAnn l an (cs Semi.<> csIn)) (HsOverLit NoExtField a) mkHsWildCardPV l = return $ L (noAnnSrcSpan l) (hsHoleExpr noAnn) mkHsTySigPV l@(EpAnn anc an csIn) a sig anns = do !cs <- getCommentsFor (locA l) return $ L (EpAnn anc an (csIn Semi.<> cs)) (ExprWithTySig anns a (hsTypeToHsSigWcType sig)) mkHsExplicitListPV l xs anns = do !cs <- getCommentsFor l return $ L (EpAnn (spanAsAnchor l) noAnn cs) (ExplicitList anns xs) mkHsSplicePV (L l a) = do !cs <- getCommentsFor l return $ fmap (HsUntypedSplice NoExtField) (L (EpAnn (spanAsAnchor l) noAnn cs) a) mkHsRecordPV opts l lrec a (fbinds, ddLoc) anns = do !cs <- getCommentsFor l r <- mkRecConstrOrUpdate opts a lrec (fbinds, ddLoc) anns checkRecordSyntax (L (EpAnn (spanAsAnchor l) noAnn cs) r) mkHsNegAppPV l a anns = do !cs <- getCommentsFor l return $ L (EpAnn (spanAsAnchor l) noAnn cs) (NegApp anns a noSyntaxExpr) mkHsSectionR_PV l op e = do !cs <- getCommentsFor l return $ L (EpAnn (spanAsAnchor l) noAnn cs) (SectionR noExtField op e) mkHsAsPatPV l v _ e = addError (mkPlainErrorMsgEnvelope l $ PsErrTypeAppWithoutSpace (unLoc v) e) >> return (L (noAnnSrcSpan l) (hsHoleExpr noAnn)) mkHsLazyPatPV l e _ = addError (mkPlainErrorMsgEnvelope l $ PsErrLazyPatWithoutSpace e) >> return (L (noAnnSrcSpan l) (hsHoleExpr noAnn)) mkHsBangPatPV l e _ = addError (mkPlainErrorMsgEnvelope l $ PsErrBangPatWithoutSpace e) >> return (L (noAnnSrcSpan l) (hsHoleExpr noAnn)) mkSumOrTuplePV = mkSumOrTupleExpr mkHsEmbTyPV l toktype ty = return $ L (noAnnSrcSpan l) $ HsEmbTy toktype (mkHsWildCardBndrs ty) mkHsArrowPV l mode arg arr res = -- In expressions, (e1 -> e2) is always parsed as a function type, -- even if ViewPatterns are enabled. exprArrowParsingMode mode $ return $ L (noAnnSrcSpan l) $ HsFunArr noExtField arr arg res mkHsMultPV pct t = return $ mkMultExpr pct t mkHsForallPV l telescope ty = return $ L (noAnnSrcSpan l) $ HsForAll noExtField (setTelescopeBndrsNameSpace varName telescope) ty checkContextPV = checkContextExpr mkQualPV l qual ty = return $ L (noAnnSrcSpan l) $ HsQual noExtField qual ty rejectPragmaPV (L _ (OpApp _ _ _ e)) = -- assuming left-associative parsing of operators rejectPragmaPV e rejectPragmaPV (L l (HsPragE _ prag _)) = addError $ mkPlainErrorMsgEnvelope (locA l) $ (PsErrUnallowedPragma prag) rejectPragmaPV _ = return () hsHoleExpr :: Maybe EpAnnUnboundVar -> HsExpr GhcPs hsHoleExpr anns = HsUnboundVar anns (mkRdrUnqual (mkVarOccFS (fsLit "_"))) instance DisambECP (PatBuilder GhcPs) where type Body (PatBuilder GhcPs) = PatBuilder ecpFromCmd' (L l c) = addFatalError $ mkPlainErrorMsgEnvelope (locA l) $ PsErrArrowCmdInPat c ecpFromExp' (L l e) = addFatalError $ mkPlainErrorMsgEnvelope (locA l) $ PsErrArrowExprInPat e ecpFromPat' (L l p) = return $ L l (PatBuilderPat p) mkHsLetPV l _ _ _ _ = addFatalError $ mkPlainErrorMsgEnvelope l PsErrLetInPat mkHsProjUpdatePV l _ _ _ _ = addFatalError $ mkPlainErrorMsgEnvelope l PsErrOverloadedRecordDotInvalid type InfixOp (PatBuilder GhcPs) = RdrName superInfixOp m = m mkHsOpAppPV l p1 op p2 = do !cs <- getCommentsFor l return $ L (EpAnn (spanAsAnchor l) noAnn cs) $ PatBuilderOpApp p1 op p2 ([],[]) mkHsLamPV l lam_variant _ _ = addFatalError $ mkPlainErrorMsgEnvelope l (PsErrLambdaInPat lam_variant) mkHsCasePV l _ _ _ = addFatalError $ mkPlainErrorMsgEnvelope l PsErrCaseInPat type FunArg (PatBuilder GhcPs) = PatBuilder GhcPs superFunArg m = m mkHsAppPV l p1 p2 = return $ L l (PatBuilderApp p1 p2) mkHsAppTypePV l p at t = do !cs <- getCommentsFor (locA l) return $ L (addCommentsToEpAnn l cs) (PatBuilderAppType p at (mkHsTyPat t)) mkHsIfPV l _ _ _ _ _ _ = addFatalError $ mkPlainErrorMsgEnvelope l PsErrIfThenElseInPat mkHsDoPV l _ _ _ _ = addFatalError $ mkPlainErrorMsgEnvelope l PsErrDoNotationInPat mkHsParPV l lpar p rpar = return $ L (noAnnSrcSpan l) (PatBuilderPar lpar p rpar) mkHsVarPV v@(getLoc -> l) = return $ L (l2l l) (PatBuilderVar v) mkHsLitPV lit@(L l a) = do checkUnboxedLitPat lit !cs <- getCommentsFor l return $ L (EpAnn (spanAsAnchor l) noAnn cs) (PatBuilderPat (LitPat noExtField a)) mkHsOverLitPV (L l a) = return $ L l (PatBuilderOverLit a) mkHsWildCardPV l = return $ L (noAnnSrcSpan l) (PatBuilderPat (WildPat noExtField)) mkHsTySigPV l p t anns = do p' <- checkLPat p let sig = mkHsPatSigType noAnn t sig_pat <- addSigPatP l p' sig anns return $ fmap PatBuilderPat sig_pat mkHsExplicitListPV l xs anns = do ps <- traverse checkLPat xs !cs <- getCommentsFor l return (L (EpAnn (spanAsAnchor l) noAnn cs) (PatBuilderPat (ListPat anns ps))) mkHsSplicePV (L l sp) = do !cs <- getCommentsFor l return $ L (EpAnn (spanAsAnchor l) noAnn cs) (PatBuilderPat (SplicePat noExtField sp)) mkHsRecordPV _ l _ a (fbinds, ddLoc) anns = do let (fs, ps) = partitionEithers fbinds if not (null ps) then addFatalError $ mkPlainErrorMsgEnvelope l PsErrOverloadedRecordDotInvalid else do !cs <- getCommentsFor l r <- mkPatRec a (mk_rec_fields fs ddLoc) anns checkRecordSyntax (L (EpAnn (spanAsAnchor l) noAnn cs) r) mkHsNegAppPV l (L lp p) anns = do lit <- case p of PatBuilderOverLit pos_lit -> return (L (l2l lp) pos_lit) _ -> patFail l $ PsErrInPat p PEIP_NegApp !cs <- getCommentsFor l return $ L (EpAnn (spanAsAnchor l) noAnn cs) (PatBuilderPat (mkNPat lit (Just noSyntaxExpr) anns)) mkHsSectionR_PV l op p = patFail l (PsErrParseRightOpSectionInPat (unLoc op) (unLoc p)) mkHsArrowPV l ArrowIsViewPat a arr b = do p <- checkLPat b !cs <- getCommentsFor l return $ L (EpAnn (spanAsAnchor l) noAnn cs) (PatBuilderPat (ViewPat tok a p)) where tok :: TokRarrow tok = case arr of HsUnrestrictedArrow x -> x _ -> -- unreachable case because in Parser.y the reduction rules for -- (a %m -> b) and (a ->. b) use ArrowIsFunType panic "mkHsArrowPV ArrowIsViewPat: expected HsUnrestrictedArrow" mkHsArrowPV l ArrowIsFunType a arr b = patFail l (PsErrTypeSyntaxInPat (PETS_FunctionArrow a arr b)) mkHsMultPV tok arg = let l = getHasLoc tok `combineSrcSpans` getLocA arg in patFail l (PsErrTypeSyntaxInPat (PETS_Multiplicity tok arg)) mkHsForallPV l tele body = patFail l (PsErrTypeSyntaxInPat (PETS_ForallTelescope tele body)) checkContextPV ctx = patFail (getLocA ctx) (PsErrTypeSyntaxInPat (PETS_ConstraintContext ctx)) mkQualPV _ _ _ = -- unreachable because mkQualPV is only called on the result -- of checkContextPV, which fails in patterns panic "mkQualPV in a pattern" mkHsAsPatPV l v at e = do p <- checkLPat e !cs <- getCommentsFor l return $ L (EpAnn (spanAsAnchor l) noAnn cs) (PatBuilderPat (AsPat at v p)) mkHsLazyPatPV l e a = do p <- checkLPat e !cs <- getCommentsFor l return $ L (EpAnn (spanAsAnchor l) noAnn cs) (PatBuilderPat (LazyPat a p)) mkHsBangPatPV l e an = do p <- checkLPat e !cs <- getCommentsFor l let pb = BangPat an p hintBangPat l pb return $ L (EpAnn (spanAsAnchor l) noAnn cs) (PatBuilderPat pb) mkSumOrTuplePV = mkSumOrTuplePat mkHsEmbTyPV l toktype ty = return $ L (noAnnSrcSpan l) $ PatBuilderPat (EmbTyPat toktype (mkHsTyPat ty)) rejectPragmaPV _ = return () -- For reasons of backwards compatibility, we can't simply add the pattern -- signature if the inner pattern is a view pattern. Consider: -- (f -> p :: t) -- There are two ways to parse it -- (f -> (p :: t)) -- legacy parse -- ((f -> p) :: t) -- future parse -- The grammar in Parser.y is structured in such a way that we get the -- future parse by default. Until we're ready to make the breaking change, -- we need to do some extra work here to push the signature under the view -- pattern (and emit a warning). addSigPatP :: SrcSpanAnnA -> LPat GhcPs -> HsPatSigType GhcPs -> TokDcolon -> PV (LPat GhcPs) addSigPatP l viewpat@(L _ ViewPat{}) sig anns = -- Test case: T24159_viewpat do { let futureParse = L l (SigPat anns viewpat sig) ; legacyParse <- go viewpat ; addPsMessage (locA l) (PsWarnViewPatternSignatures legacyParse futureParse) ; return legacyParse } where sig_loc_no_comments :: SrcSpan sig_loc_no_comments = getLocA (hsps_body sig) -- Test case for comments and locations preservation: Test24159 go :: LPat GhcPs -> PV (LPat GhcPs) go (L (EpAnn (EpaSpan view_pat_loc) anns cs1) (ViewPat anns' e' p')) = do sig' <- go p' let new_loc = view_pat_loc `combineSrcSpans` sig_loc_no_comments cs2 <- getCommentsFor new_loc let ep_ann_loc = EpAnn (spanAsAnchor new_loc) anns (cs1 Semi.<> cs2) pure (L ep_ann_loc (ViewPat anns' e' sig')) go p = pure $ L new_loc (SigPat anns p sig) where new_loc = noAnnSrcSpan ((getLocA p) `combineSrcSpans` sig_loc_no_comments) addSigPatP l p sig anns = do return $ L l (SigPat anns p sig) {- Note [Arrow parsing mode] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Consider this example: f (K (a -> b)) = () A pattern of the form (a -> b) could be parsed in one of two ways: * a view pattern `viewfn -> pat` (with ViewPatterns) * a function type `t1 -> t2` (with RequiredTypeArguments) This depends on the enabled extensions: NoViewPatterns, RequiredTypeArguments => function type NoViewPatterns, NoRequiredTypeArguments => error (suggest ViewPatterns) ViewPatterns, RequiredTypeArguments => view pattern ViewPatterns, NoRequiredTypeArguments => view pattern The decision how to parse arrow patterns (p1 -> p2) is captured by the `ArrowParsingMode` data type, produced in `withArrowParsingMode` and consumed in `mkHsArrowPV`. Naively, one might expect to see the following definition: -- a simple (but insufficient) definition data ArrowParsingMode = ArrowIsViewPat | ArrowIsFunType However, there is a slight complication that leads us to parameterize these constructor with GADT type indices. In a pattern (p1 -> p2), what is the AST type to represent the LHS `p1`? It depends: * if (p1 -> p2) is a view pattern, `p1` is an HsExpr * if (p1 -> p2) is a function type, `p1` is a Pat (PatBuilder) And since the decision how to parse `p1` depends on the arrow parsing mode, we could try to encode the LHS type as a GADT index: -- a less simple (but still insufficient) definition data ArrowParsingMode lhs where ArrowIsViewPat :: ArrowParsingMode (PatBuilder GhcPs) ArrowIsFunType :: ArrowParsingMode (HsExpr GhcPs) This definition would suffice for parsing patterns, but remember that expressions, commands, and patterns are all parsed using a unified framework `DisambECP`, as described in Note [Ambiguous syntactic categories]. In an expression (e1 -> e2), the LHS is always represented by an HsExpr. We can account for this with a further refinement of the definition: -- actual definition data ArrowParsingMode lhs rhs where ArrowIsViewPat :: ArrowParsingMode (HsExpr GhcPs) b ArrowIsFunType :: ArrowParsingMode b b So when parsing a view pattern, the LHS is an HsExpr; and when parsing a function type, the type of the LHS is assumed to match the type of the RHS, which works out just right both for expressions and patterns. -} -- The arrow parsing mode is selected depending on the enabled extensions and -- determines how we parse patterns of the form (p1 -> p2). See Note [Arrow parsing mode] data ArrowParsingMode lhs rhs where ArrowIsViewPat :: ArrowParsingMode (HsExpr GhcPs) b -- the LHS is always of type HsExpr ArrowIsFunType :: ArrowParsingMode b b -- the LHS is of the same type as RHS -- When parsing an expression (e1 -> e2), the LHS `e1` is an HsExpr regardless of -- the arrow parsing mode. `exprArrowParsingMode` proves this to the type checker. -- See Note [Arrow parsing mode] exprArrowParsingMode :: ArrowParsingMode lhs (HsExpr GhcPs) -> (lhs ~ HsExpr GhcPs => r) -> r exprArrowParsingMode ArrowIsViewPat k = k exprArrowParsingMode ArrowIsFunType k = k -- Check the enabled extensions and select the appropriate ArrowParsingMode, -- then pass it to a continuation. See Note [Arrow parsing mode] withArrowParsingMode :: DisambECP b => (forall lhs. DisambECP lhs => ArrowParsingMode lhs b -> PV r) -> PV r withArrowParsingMode cont = do vpEnabled <- getBit ViewPatternsBit rtaEnabled <- getBit RequiredTypeArgumentsBit if | vpEnabled -> cont ArrowIsViewPat | rtaEnabled -> cont ArrowIsFunType | otherwise -> cont ArrowIsViewPat -- Error message should suggest ViewPatterns in patterns -- Type-restricted variant of `withArrowParsingMode` to aid type inference (#25103) withArrowParsingMode' :: DisambECP b => (forall lhs. DisambECP lhs => ArrowParsingMode lhs b -> PV (LocatedA b)) -> PV (LocatedA b) withArrowParsingMode' = withArrowParsingMode -- When a forall-type occurs in term syntax, forall-bound variables should -- inhabit the term namespace `varName` rather than the usual `tvName`. -- See Note [Types in terms]. -- -- Since type variable binders in a `HsForAllTelescope` produced by the -- `forall_telescope` nonterminal have their namespaces set to `tvName`, -- we use `setTelescopeBndrsNameSpace` to fix them up. setTelescopeBndrsNameSpace :: NameSpace -> HsForAllTelescope GhcPs -> HsForAllTelescope GhcPs setTelescopeBndrsNameSpace ns forall_telescope = case forall_telescope of HsForAllInvis x bndrs -> HsForAllInvis x (set_bndrs_ns bndrs) HsForAllVis x bndrs -> HsForAllVis x (set_bndrs_ns bndrs) where set_bndrs_ns :: [LHsTyVarBndr flag GhcPs] -> [LHsTyVarBndr flag GhcPs] set_bndrs_ns = map (setLHsTyVarBndrNameSpace ns) setLHsTyVarBndrNameSpace :: NameSpace -> LHsTyVarBndr flag GhcPs -> LHsTyVarBndr flag GhcPs setLHsTyVarBndrNameSpace ns (L l tvb) = L l tvb' where tvb' = tvb { tvb_var = setHsBndrVarNameSpace ns (tvb_var tvb) } setHsBndrVarNameSpace :: NameSpace -> HsBndrVar GhcPs -> HsBndrVar GhcPs setHsBndrVarNameSpace ns (HsBndrVar x (L l rdr)) = HsBndrVar x (L l rdr') where rdr' = setRdrNameSpace rdr ns setHsBndrVarNameSpace _ (HsBndrWildCard x) = HsBndrWildCard x -- | Ensure that a literal pattern isn't of type Addr#, Float#, Double#. checkUnboxedLitPat :: Located (HsLit GhcPs) -> PV () checkUnboxedLitPat (L loc lit) = case lit of -- Don't allow primitive string literal patterns. -- See #13260. HsStringPrim {} -> addError $ mkPlainErrorMsgEnvelope loc $ (PsErrIllegalUnboxedStringInPat lit) -- Don't allow Float#/Double# literal patterns. -- See #9238 and Note [Rules for floating-point comparisons] -- in GHC.Core.Opt.ConstantFold. _ | is_floating_lit lit -> addError $ mkPlainErrorMsgEnvelope loc $ (PsErrIllegalUnboxedFloatingLitInPat lit) | otherwise -> return () where is_floating_lit :: HsLit GhcPs -> Bool is_floating_lit (HsFloatPrim {}) = True is_floating_lit (HsDoublePrim {}) = True is_floating_lit _ = False mkPatRec :: LocatedA (PatBuilder GhcPs) -> HsRecFields GhcPs (LocatedA (PatBuilder GhcPs)) -> (Maybe (EpToken "{"), Maybe (EpToken "}")) -> PV (PatBuilder GhcPs) mkPatRec (unLoc -> PatBuilderVar c) (HsRecFields x fs dd) anns | isRdrDataCon (unLoc c) = do fs <- mapM checkPatField fs return $ PatBuilderPat $ ConPat { pat_con_ext = anns , pat_con = c , pat_args = RecCon (HsRecFields x fs dd) } mkPatRec p _ _ = addFatalError $ mkPlainErrorMsgEnvelope (getLocA p) $ (PsErrInvalidRecordCon (unLoc p)) -- | Disambiguate constructs that may appear when we do not know -- ahead of time whether we are parsing a type or a newtype/data constructor. -- -- See Note [Ambiguous syntactic categories] for the general idea. -- -- See Note [Parsing data constructors is hard] for the specific issue this -- particular class is solving. -- class DisambTD b where -- | Process the head of a type-level function/constructor application, -- i.e. the @H@ in @H a b c@. mkHsAppTyHeadPV :: LHsType GhcPs -> PV (LocatedA b) -- | Disambiguate @f x@ (function application or prefix data constructor). mkHsAppTyPV :: LocatedA b -> LHsType GhcPs -> PV (LocatedA b) -- | Disambiguate @f \@t@ (visible kind application) mkHsAppKindTyPV :: LocatedA b -> EpToken "@" -> LHsType GhcPs -> PV (LocatedA b) -- | Disambiguate @f \# x@ (infix operator) mkHsOpTyPV :: PromotionFlag -> LHsType GhcPs -> LocatedN RdrName -> LHsType GhcPs -> PV (LocatedA b) -- | Disambiguate @{-\# UNPACK \#-} t@ (unpack/nounpack pragma) mkUnpackednessPV :: Located UnpackednessPragma -> LocatedA b -> PV (LocatedA b) instance DisambTD (HsType GhcPs) where mkHsAppTyHeadPV = return mkHsAppTyPV t1 t2 = return (mkHsAppTy t1 t2) mkHsAppKindTyPV t at ki = return (mkHsAppKindTy at t ki) mkHsOpTyPV prom t1 op t2 = do let (L l ty) = mkLHsOpTy prom t1 op t2 !cs <- getCommentsFor (locA l) return (L (addCommentsToEpAnn l cs) ty) mkUnpackednessPV = addUnpackednessP dataConBuilderCon :: LocatedA DataConBuilder -> LocatedN RdrName dataConBuilderCon (L _ (PrefixDataConBuilder _ dc)) = dc dataConBuilderCon (L _ (InfixDataConBuilder _ dc _)) = dc dataConBuilderDetails :: LocatedA DataConBuilder -> HsConDeclH98Details GhcPs -- Detect when the record syntax is used: -- data T = MkT { ... } dataConBuilderDetails (L _ (PrefixDataConBuilder flds _)) | [L (EpAnn anc _ cs) (HsRecTy an fields)] <- toList flds = RecCon (L (EpAnn anc an cs) fields) -- Normal prefix constructor, e.g. data T = MkT A B C dataConBuilderDetails (L _ (PrefixDataConBuilder flds _)) = PrefixCon noTypeArgs (map hsLinear (toList flds)) -- Infix constructor, e.g. data T = Int :! Bool dataConBuilderDetails (L (EpAnn _ _ csl) (InfixDataConBuilder (L (EpAnn anc ann csll) lhs) _ rhs)) = InfixCon (hsLinear (L (EpAnn anc ann (csl Semi.<> csll)) lhs)) (hsLinear rhs) instance DisambTD DataConBuilder where mkHsAppTyHeadPV = tyToDataConBuilder mkHsAppTyPV (L l (PrefixDataConBuilder flds fn)) t = return $ L (noAnnSrcSpan $ combineSrcSpans (locA l) (getLocA t)) (PrefixDataConBuilder (flds `snocOL` t) fn) mkHsAppTyPV (L _ InfixDataConBuilder{}) _ = -- This case is impossible because of the way -- the grammar in Parser.y is written (see infixtype/ftype). panic "mkHsAppTyPV: InfixDataConBuilder" mkHsAppKindTyPV lhs at ki = addFatalError $ mkPlainErrorMsgEnvelope (getEpTokenSrcSpan at) $ (PsErrUnexpectedKindAppInDataCon (unLoc lhs) (unLoc ki)) mkHsOpTyPV prom lhs tc rhs = do check_no_ops (unLoc rhs) -- check the RHS because parsing type operators is right-associative data_con <- eitherToP $ tyConToDataCon tc !cs <- getCommentsFor (locA l) checkNotPromotedDataCon prom data_con return $ L (addCommentsToEpAnn l cs) (InfixDataConBuilder lhs data_con rhs) where l = combineLocsA lhs rhs check_no_ops (HsBangTy _ _ t) = check_no_ops (unLoc t) check_no_ops (HsOpTy{}) = addError $ mkPlainErrorMsgEnvelope (locA l) $ (PsErrInvalidInfixDataCon (unLoc lhs) (unLoc tc) (unLoc rhs)) check_no_ops _ = return () mkUnpackednessPV unpk constr_stuff | L _ (InfixDataConBuilder lhs data_con rhs) <- constr_stuff = -- When the user writes data T = {-# UNPACK #-} Int :+ Bool -- we apply {-# UNPACK #-} to the LHS do lhs' <- addUnpackednessP unpk lhs let l = combineLocsA (reLoc unpk) constr_stuff return $ L l (InfixDataConBuilder lhs' data_con rhs) | otherwise = do addError $ mkPlainErrorMsgEnvelope (getLoc unpk) PsErrUnpackDataCon return constr_stuff tyToDataConBuilder :: LHsType GhcPs -> PV (LocatedA DataConBuilder) tyToDataConBuilder (L l (HsTyVar _ prom v)) = do data_con <- eitherToP $ tyConToDataCon v checkNotPromotedDataCon prom data_con return $ L l (PrefixDataConBuilder nilOL data_con) tyToDataConBuilder (L l (HsTupleTy _ HsBoxedOrConstraintTuple ts)) = do let data_con = L (l2l l) (getRdrName (tupleDataCon Boxed (length ts))) return $ L l (PrefixDataConBuilder (toOL ts) data_con) tyToDataConBuilder (L l (HsTupleTy _ HsUnboxedTuple ts)) = do let data_con = L (l2l l) (getRdrName (tupleDataCon Unboxed (length ts))) return $ L l (PrefixDataConBuilder (toOL ts) data_con) tyToDataConBuilder t = addFatalError $ mkPlainErrorMsgEnvelope (getLocA t) $ (PsErrInvalidDataCon (unLoc t)) -- | Rejects declarations such as @data T = 'MkT@ (note the leading tick). checkNotPromotedDataCon :: PromotionFlag -> LocatedN RdrName -> PV () checkNotPromotedDataCon NotPromoted _ = return () checkNotPromotedDataCon IsPromoted (L l name) = addError $ mkPlainErrorMsgEnvelope (locA l) $ PsErrIllegalPromotionQuoteDataCon name mkUnboxedSumCon :: LHsType GhcPs -> ConTag -> Arity -> (LocatedN RdrName, HsConDeclH98Details GhcPs) mkUnboxedSumCon t tag arity = (noLocA (getRdrName (sumDataCon tag arity)), PrefixCon noTypeArgs [hsLinear t]) {- Note [Ambiguous syntactic categories] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ There are places in the grammar where we do not know whether we are parsing an expression or a pattern without unlimited lookahead (which we do not have in 'happy'): View patterns: f (Con a b ) = ... -- 'Con a b' is a pattern f (Con a b -> x) = ... -- 'Con a b' is an expression do-notation: do { Con a b <- x } -- 'Con a b' is a pattern do { Con a b } -- 'Con a b' is an expression Guards: x | True <- p && q = ... -- 'True' is a pattern x | True = ... -- 'True' is an expression Top-level value/function declarations (FunBind/PatBind): f ! a -- TH splice f ! a = ... -- function declaration Until we encounter the = sign, we don't know if it's a top-level TemplateHaskell splice where ! is used, or if it's a function declaration where ! is bound. There are also places in the grammar where we do not know whether we are parsing an expression or a command: proc x -> do { (stuff) -< x } -- 'stuff' is an expression proc x -> do { (stuff) } -- 'stuff' is a command Until we encounter arrow syntax (-<) we don't know whether to parse 'stuff' as an expression or a command. In fact, do-notation is subject to both ambiguities: proc x -> do { (stuff) -< x } -- 'stuff' is an expression proc x -> do { (stuff) <- f -< x } -- 'stuff' is a pattern proc x -> do { (stuff) } -- 'stuff' is a command There are many possible solutions to this problem. For an overview of the ones we decided against, see Note [Resolving parsing ambiguities: non-taken alternatives] The solution that keeps basic definitions (such as HsExpr) clean, keeps the concerns local to the parser, and does not require duplication of hsSyn types, or an extra pass over the entire AST, is to parse into an overloaded parser-validator (a so-called tagless final encoding): class DisambECP b where ... instance DisambECP (HsCmd GhcPs) where ... instance DisambECP (HsExp GhcPs) where ... instance DisambECP (PatBuilder GhcPs) where ... The 'DisambECP' class contains functions to build and validate 'b'. For example, to add parentheses we have: mkHsParPV :: DisambECP b => SrcSpan -> Located b -> PV (Located b) 'mkHsParPV' will wrap the inner value in HsCmdPar for commands, HsPar for expressions, and 'PatBuilderPar' for patterns (later transformed into ParPat, see Note [PatBuilder]). Consider the 'alts' production used to parse case-of alternatives: alts :: { Located ([AddEpAnn],[LMatch GhcPs (LHsExpr GhcPs)]) } : alts1 { sL1 $1 (fst $ unLoc $1,snd $ unLoc $1) } | ';' alts { sLL $1 $> ((mj AnnSemi $1:(fst $ unLoc $2)),snd $ unLoc $2) } We abstract over LHsExpr GhcPs, and it becomes: alts :: { forall b. DisambECP b => PV (Located ([AddEpAnn],[LMatch GhcPs (Located b)])) } : alts1 { $1 >>= \ $1 -> return $ sL1 $1 (fst $ unLoc $1,snd $ unLoc $1) } | ';' alts { $2 >>= \ $2 -> return $ sLL $1 $> ((mj AnnSemi $1:(fst $ unLoc $2)),snd $ unLoc $2) } Compared to the initial definition, the added bits are: forall b. DisambECP b => PV ( ... ) -- in the type signature $1 >>= \ $1 -> return $ -- in one reduction rule $2 >>= \ $2 -> return $ -- in another reduction rule The overhead is constant relative to the size of the rest of the reduction rule, so this approach scales well to large parser productions. Note that we write ($1 >>= \ $1 -> ...), so the second $1 is in a binding position and shadows the previous $1. We can do this because internally 'happy' desugars $n to happy_var_n, and the rationale behind this idiom is to be able to write (sLL $1 $>) later on. The alternative would be to write this as ($1 >>= \ fresh_name -> ...), but then we couldn't refer to the last fresh name as $>. Finally, we instantiate the polymorphic type to a concrete one, and run the parser-validator, for example: stmt :: { forall b. DisambECP b => PV (LStmt GhcPs (Located b)) } e_stmt :: { LStmt GhcPs (LHsExpr GhcPs) } : stmt {% runPV $1 } In e_stmt, three things happen: 1. we instantiate: b ~ HsExpr GhcPs 2. we embed the PV computation into P by using runPV 3. we run validation by using a monadic production, {% ... } At this point the ambiguity is resolved. -} {- Note [Resolving parsing ambiguities: non-taken alternatives] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Alternative I, extra constructors in GHC.Hs.Expr ------------------------------------------------ We could add extra constructors to HsExpr to represent command-specific and pattern-specific syntactic constructs. Under this scheme, we parse patterns and commands as expressions and rejig later. This is what GHC used to do, and it polluted 'HsExpr' with irrelevant constructors: * for commands: 'HsArrForm', 'HsArrApp' * for patterns: 'EWildPat', 'EAsPat', 'EViewPat', 'ELazyPat' (As of now, we still do that for patterns, but we plan to fix it). There are several issues with this: * The implementation details of parsing are leaking into hsSyn definitions. * Code that uses HsExpr has to panic on these impossible-after-parsing cases. * HsExpr is arbitrarily selected as the extension basis. Why not extend HsCmd or HsPat with extra constructors instead? Alternative II, extra constructors in GHC.Hs.Expr for GhcPs ----------------------------------------------------------- We could address some of the problems with Alternative I by using Trees That Grow and extending HsExpr only in the GhcPs pass. However, GhcPs corresponds to the output of parsing, not to its intermediate results, so we wouldn't want them there either. Alternative III, extra constructors in GHC.Hs.Expr for GhcPrePs --------------------------------------------------------------- We could introduce a new pass, GhcPrePs, to keep GhcPs pristine. Unfortunately, creating a new pass would significantly bloat conversion code and slow down the compiler by adding another linear-time pass over the entire AST. For example, in order to build HsExpr GhcPrePs, we would need to build HsLocalBinds GhcPrePs (as part of HsLet), and we never want HsLocalBinds GhcPrePs. Alternative IV, sum type and bottom-up data flow ------------------------------------------------ Expressions and commands are disjoint. There are no user inputs that could be interpreted as either an expression or a command depending on outer context: 5 -- definitely an expression x -< y -- definitely a command Even though we have both 'HsLam' and 'HsCmdLam', we can look at the body to disambiguate: \p -> 5 -- definitely an expression \p -> x -< y -- definitely a command This means we could use a bottom-up flow of information to determine whether we are parsing an expression or a command, using a sum type for intermediate results: Either (LHsExpr GhcPs) (LHsCmd GhcPs) There are two problems with this: * We cannot handle the ambiguity between expressions and patterns, which are not disjoint. * Bottom-up flow of information leads to poor error messages. Consider if ... then 5 else (x -< y) Do we report that '5' is not a valid command or that (x -< y) is not a valid expression? It depends on whether we want the entire node to be 'HsIf' or 'HsCmdIf', and this information flows top-down, from the surrounding parsing context (are we in 'proc'?) Alternative V, backtracking with parser combinators --------------------------------------------------- One might think we could sidestep the issue entirely by using a backtracking parser and doing something along the lines of (try pExpr <|> pPat). Turns out, this wouldn't work very well, as there can be patterns inside expressions (e.g. via 'case', 'let', 'do') and expressions inside patterns (e.g. view patterns). To handle this, we would need to backtrack while backtracking, and unbound levels of backtracking lead to very fragile performance. Alternative VI, an intermediate data type ----------------------------------------- There are common syntactic elements of expressions, commands, and patterns (e.g. all of them must have balanced parentheses), and we can capture this common structure in an intermediate data type, Frame: data Frame = FrameVar RdrName -- ^ Identifier: Just, map, BS.length | FrameTuple [LTupArgFrame] Boxity -- ^ Tuple (section): (a,b) (a,b,c) (a,,) (,a,) | FrameTySig LFrame (LHsSigWcType GhcPs) -- ^ Type signature: x :: ty | FramePar (SrcSpan, SrcSpan) LFrame -- ^ Parentheses | FrameIf LFrame LFrame LFrame -- ^ If-expression: if p then x else y | FrameCase LFrame [LFrameMatch] -- ^ Case-expression: case x of { p1 -> e1; p2 -> e2 } | FrameDo HsStmtContextRn [LFrameStmt] -- ^ Do-expression: do { s1; a <- s2; s3 } ... | FrameExpr (HsExpr GhcPs) -- unambiguously an expression | FramePat (HsPat GhcPs) -- unambiguously a pattern | FrameCommand (HsCmd GhcPs) -- unambiguously a command To determine which constructors 'Frame' needs to have, we take the union of intersections between HsExpr, HsCmd, and HsPat. The intersection between HsPat and HsExpr: HsPat = VarPat | TuplePat | SigPat | ParPat | ... HsExpr = HsVar | ExplicitTuple | ExprWithTySig | HsPar | ... ------------------------------------------------------------------- Frame = FrameVar | FrameTuple | FrameTySig | FramePar | ... The intersection between HsCmd and HsExpr: HsCmd = HsCmdIf | HsCmdCase | HsCmdDo | HsCmdPar HsExpr = HsIf | HsCase | HsDo | HsPar ------------------------------------------------ Frame = FrameIf | FrameCase | FrameDo | FramePar The intersection between HsCmd and HsPat: HsPat = ParPat | ... HsCmd = HsCmdPar | ... ----------------------- Frame = FramePar | ... Take the union of each intersection and this yields the final 'Frame' data type. The problem with this approach is that we end up duplicating a good portion of hsSyn: Frame for HsExpr, HsPat, HsCmd TupArgFrame for HsTupArg FrameMatch for Match FrameStmt for StmtLR FrameGRHS for GRHS FrameGRHSs for GRHSs ... Alternative VII, a product type ------------------------------- We could avoid the intermediate representation of Alternative VI by parsing into a product of interpretations directly: type ExpCmdPat = ( PV (LHsExpr GhcPs) , PV (LHsCmd GhcPs) , PV (LHsPat GhcPs) ) This means that in positions where we do not know whether to produce expression, a pattern, or a command, we instead produce a parser-validator for each possible option. Then, as soon as we have parsed far enough to resolve the ambiguity, we pick the appropriate component of the product, discarding the rest: checkExpOf3 (e, _, _) = e -- interpret as an expression checkCmdOf3 (_, c, _) = c -- interpret as a command checkPatOf3 (_, _, p) = p -- interpret as a pattern We can easily define ambiguities between arbitrary subsets of interpretations. For example, when we know ahead of type that only an expression or a command is possible, but not a pattern, we can use a smaller type: type ExpCmd = (PV (LHsExpr GhcPs), PV (LHsCmd GhcPs)) checkExpOf2 (e, _) = e -- interpret as an expression checkCmdOf2 (_, c) = c -- interpret as a command However, there is a slight problem with this approach, namely code duplication in parser productions. Consider the 'alts' production used to parse case-of alternatives: alts :: { Located ([AddEpAnn],[LMatch GhcPs (LHsExpr GhcPs)]) } : alts1 { sL1 $1 (fst $ unLoc $1,snd $ unLoc $1) } | ';' alts { sLL $1 $> ((mj AnnSemi $1:(fst $ unLoc $2)),snd $ unLoc $2) } Under the new scheme, we have to completely duplicate its type signature and each reduction rule: alts :: { ( PV (Located ([AddEpAnn],[LMatch GhcPs (LHsExpr GhcPs)])) -- as an expression , PV (Located ([AddEpAnn],[LMatch GhcPs (LHsCmd GhcPs)])) -- as a command ) } : alts1 { ( checkExpOf2 $1 >>= \ $1 -> return $ sL1 $1 (fst $ unLoc $1,snd $ unLoc $1) , checkCmdOf2 $1 >>= \ $1 -> return $ sL1 $1 (fst $ unLoc $1,snd $ unLoc $1) ) } | ';' alts { ( checkExpOf2 $2 >>= \ $2 -> return $ sLL $1 $> ((mj AnnSemi $1:(fst $ unLoc $2)),snd $ unLoc $2) , checkCmdOf2 $2 >>= \ $2 -> return $ sLL $1 $> ((mj AnnSemi $1:(fst $ unLoc $2)),snd $ unLoc $2) ) } And the same goes for other productions: 'altslist', 'alts1', 'alt', 'alt_rhs', 'ralt', 'gdpats', 'gdpat', 'exp', ... and so on. That is a lot of code! Alternative VIII, a function from a GADT ---------------------------------------- We could avoid code duplication of the Alternative VII by representing the product as a function from a GADT: data ExpCmdG b where ExpG :: ExpCmdG HsExpr CmdG :: ExpCmdG HsCmd type ExpCmd = forall b. ExpCmdG b -> PV (Located (b GhcPs)) checkExp :: ExpCmd -> PV (LHsExpr GhcPs) checkCmd :: ExpCmd -> PV (LHsCmd GhcPs) checkExp f = f ExpG -- interpret as an expression checkCmd f = f CmdG -- interpret as a command Consider the 'alts' production used to parse case-of alternatives: alts :: { Located ([AddEpAnn],[LMatch GhcPs (LHsExpr GhcPs)]) } : alts1 { sL1 $1 (fst $ unLoc $1,snd $ unLoc $1) } | ';' alts { sLL $1 $> ((mj AnnSemi $1:(fst $ unLoc $2)),snd $ unLoc $2) } We abstract over LHsExpr, and it becomes: alts :: { forall b. ExpCmdG b -> PV (Located ([AddEpAnn],[LMatch GhcPs (Located (b GhcPs))])) } : alts1 { \tag -> $1 tag >>= \ $1 -> return $ sL1 $1 (fst $ unLoc $1,snd $ unLoc $1) } | ';' alts { \tag -> $2 tag >>= \ $2 -> return $ sLL $1 $> ((mj AnnSemi $1:(fst $ unLoc $2)),snd $ unLoc $2) } Note that 'ExpCmdG' is a singleton type, the value is completely determined by the type: when (b~HsExpr), tag = ExpG when (b~HsCmd), tag = CmdG This is a clear indication that we can use a class to pass this value behind the scenes: class ExpCmdI b where expCmdG :: ExpCmdG b instance ExpCmdI HsExpr where expCmdG = ExpG instance ExpCmdI HsCmd where expCmdG = CmdG And now the 'alts' production is simplified, as we no longer need to thread 'tag' explicitly: alts :: { forall b. ExpCmdI b => PV (Located ([AddEpAnn],[LMatch GhcPs (Located (b GhcPs))])) } : alts1 { $1 >>= \ $1 -> return $ sL1 $1 (fst $ unLoc $1,snd $ unLoc $1) } | ';' alts { $2 >>= \ $2 -> return $ sLL $1 $> ((mj AnnSemi $1:(fst $ unLoc $2)),snd $ unLoc $2) } This encoding works well enough, but introduces an extra GADT unlike the tagless final encoding, and there's no need for this complexity. -} {- Note [PatBuilder] ~~~~~~~~~~~~~~~~~~~~ Unlike HsExpr or HsCmd, the Pat type cannot accommodate all intermediate forms, so we introduce the notion of a PatBuilder. Consider a pattern like this: Con a b c We parse arguments to "Con" one at a time in the fexp aexp parser production, building the result with mkHsAppPV, so the intermediate forms are: 1. Con 2. Con a 3. Con a b 4. Con a b c In 'HsExpr', we have 'HsApp', so the intermediate forms are represented like this (pseudocode): 1. "Con" 2. HsApp "Con" "a" 3. HsApp (HsApp "Con" "a") "b" 3. HsApp (HsApp (HsApp "Con" "a") "b") "c" Similarly, in 'HsCmd' we have 'HsCmdApp'. In 'Pat', however, what we have instead is 'ConPatIn', which is very awkward to modify and thus unsuitable for the intermediate forms. We also need an intermediate representation to postpone disambiguation between FunBind and PatBind. Consider: a `Con` b = ... a `fun` b = ... How do we know that (a `Con` b) is a PatBind but (a `fun` b) is a FunBind? We learn this by inspecting an intermediate representation in 'isFunLhs' and seeing that 'Con' is a data constructor but 'f' is not. We need an intermediate representation capable of representing both a FunBind and a PatBind, so Pat is insufficient. PatBuilder is an extension of Pat that is capable of representing intermediate parsing results for patterns and function bindings: data PatBuilder p = PatBuilderPat (Pat p) | PatBuilderApp (LocatedA (PatBuilder p)) (LocatedA (PatBuilder p)) | PatBuilderOpApp (LocatedA (PatBuilder p)) (LocatedA RdrName) (LocatedA (PatBuilder p)) ... It can represent any pattern via 'PatBuilderPat', but it also has a variety of other constructors which were added by following a simple principle: we never pattern match on the pattern stored inside 'PatBuilderPat'. -} --------------------------------------------------------------------------- -- Miscellaneous utilities -- | Check if a fixity is valid. We support bypassing the usual bound checks -- for some special operators. checkPrecP :: Located (SourceText,Int) -- ^ precedence -> Located (OrdList (LocatedN RdrName)) -- ^ operators -> P () checkPrecP (L l (_,i)) (L _ ol) | 0 <= i, i <= maxPrecedence = pure () | all specialOp ol = pure () | otherwise = addFatalError $ mkPlainErrorMsgEnvelope l (PsErrPrecedenceOutOfRange i) where -- If you change this, consider updating Note [Fixity of (->)] in GHC/Types.hs specialOp op = unLoc op == getRdrName unrestrictedFunTyCon mkRecConstrOrUpdate :: Bool -> LHsExpr GhcPs -> SrcSpan -> ([Fbind (HsExpr GhcPs)], Maybe SrcSpan) -> (Maybe (EpToken "{"), Maybe (EpToken "}")) -> PV (HsExpr GhcPs) mkRecConstrOrUpdate _ (L _ (HsVar _ (L l c))) _lrec (fbinds,dd) anns | isRdrDataCon c = do let (fs, ps) = partitionEithers fbinds case ps of p:_ -> addFatalError $ mkPlainErrorMsgEnvelope (getLocA p) $ PsErrOverloadedRecordDotInvalid _ -> return (mkRdrRecordCon (L l c) (mk_rec_fields fs dd) anns) mkRecConstrOrUpdate overloaded_update exp _ (fs,dd) anns | Just dd_loc <- dd = addFatalError $ mkPlainErrorMsgEnvelope dd_loc $ PsErrDotsInRecordUpdate | otherwise = mkRdrRecordUpd overloaded_update exp fs anns mkRdrRecordUpd :: Bool -> LHsExpr GhcPs -> [Fbind (HsExpr GhcPs)] -> (Maybe (EpToken "{"), Maybe (EpToken "}")) -> PV (HsExpr GhcPs) mkRdrRecordUpd overloaded_on exp@(L loc _) fbinds anns = do -- We do not need to know if OverloadedRecordDot is in effect. We do -- however need to know if OverloadedRecordUpdate (passed in -- overloaded_on) is in effect because it affects the Left/Right nature -- of the RecordUpd value we calculate. let (fs, ps) = partitionEithers fbinds fs' :: [LHsRecUpdField GhcPs GhcPs] fs' = map (fmap mk_rec_upd_field) fs case overloaded_on of False | not $ null ps -> -- A '.' was found in an update and OverloadedRecordUpdate isn't on. addFatalError $ mkPlainErrorMsgEnvelope (locA loc) PsErrOverloadedRecordUpdateNotEnabled False -> -- This is just a regular record update. return RecordUpd { rupd_ext = anns , rupd_expr = exp , rupd_flds = RegularRecUpdFields { xRecUpdFields = noExtField , recUpdFields = fs' } } -- This is a RecordDotSyntax update. True -> do let qualifiedFields = [ L l lbl | L _ (HsFieldBind _ (L l lbl) _ _) <- fs' , isQual . fieldOccRdrName $ lbl ] case qualifiedFields of qf:_ -> addFatalError $ mkPlainErrorMsgEnvelope (getLocA qf) $ PsErrOverloadedRecordUpdateNoQualifiedFields _ -> return $ RecordUpd { rupd_ext = anns , rupd_expr = exp , rupd_flds = OverloadedRecUpdFields { xOLRecUpdFields = noExtField , olRecUpdFields = toProjUpdates fbinds } } where toProjUpdates :: [Fbind (HsExpr GhcPs)] -> [LHsRecUpdProj GhcPs] toProjUpdates = map (\case { Right p -> p; Left f -> recFieldToProjUpdate f }) -- Convert a top-level field update like {foo=2} or {bar} (punned) -- to a projection update. recFieldToProjUpdate :: LHsRecField GhcPs (LHsExpr GhcPs) -> LHsRecUpdProj GhcPs recFieldToProjUpdate (L l (HsFieldBind anns (L _ (FieldOcc _ (L loc rdr))) arg pun)) = -- The idea here is to convert the label to a singleton [FastString]. let f = occNameFS . rdrNameOcc $ rdr fl = DotFieldOcc noAnn (L loc (FieldLabelString f)) lf = locA loc in mkRdrProjUpdate l (L lf [L (l2l loc) fl]) (punnedVar f) pun anns where -- If punning, compute HsVar "f" otherwise just arg. This -- has the effect that sentinel HsVar "pun-rhs" is replaced -- by HsVar "f" here, before the update is written to a -- setField expressions. punnedVar :: FastString -> LHsExpr GhcPs punnedVar f = if not pun then arg else noLocA . HsVar noExtField . noLocA . mkRdrUnqual . mkVarOccFS $ f mkRdrRecordCon :: LocatedN RdrName -> HsRecordBinds GhcPs -> (Maybe (EpToken "{"), Maybe (EpToken "}")) -> HsExpr GhcPs mkRdrRecordCon con flds anns = RecordCon { rcon_ext = anns, rcon_con = con, rcon_flds = flds } mk_rec_fields :: [LocatedA (HsRecField GhcPs arg)] -> Maybe SrcSpan -> HsRecFields GhcPs arg mk_rec_fields fs Nothing = HsRecFields { rec_ext = noExtField, rec_flds = fs, rec_dotdot = Nothing } mk_rec_fields fs (Just s) = HsRecFields { rec_ext = noExtField, rec_flds = fs , rec_dotdot = Just (L (l2l s) (RecFieldsDotDot $ length fs)) } mk_rec_upd_field :: HsRecField GhcPs (LHsExpr GhcPs) -> HsRecUpdField GhcPs GhcPs mk_rec_upd_field (HsFieldBind noAnn (L loc (FieldOcc _ rdr)) arg pun) = HsFieldBind noAnn (L loc (FieldOcc noExtField rdr)) arg pun mkInlinePragma :: SourceText -> (InlineSpec, RuleMatchInfo) -> Maybe Activation -> InlinePragma -- The (Maybe Activation) is because the user can omit -- the activation spec (and usually does) mkInlinePragma src (inl, match_info) mb_act = InlinePragma { inl_src = src -- See Note [Pragma source text] in "GHC.Types.SourceText" , inl_inline = inl , inl_sat = Nothing , inl_act = act , inl_rule = match_info } where act = case mb_act of Just act -> act Nothing -> -- No phase specified case inl of NoInline _ -> NeverActive Opaque _ -> NeverActive _other -> AlwaysActive mkOpaquePragma :: SourceText -> InlinePragma mkOpaquePragma src = InlinePragma { inl_src = src , inl_inline = Opaque src , inl_sat = Nothing -- By marking the OPAQUE pragma NeverActive we stop -- (constructor) specialisation on OPAQUE things. -- -- See Note [OPAQUE pragma] , inl_act = NeverActive , inl_rule = FunLike } checkNewOrData :: SrcSpan -> RdrName -> Bool -> NewOrData -> [LConDecl GhcPs] -> P (DataDefnCons (LConDecl GhcPs)) checkNewOrData span name is_type_data = curry $ \ case (NewType, [a]) -> pure $ NewTypeCon a (DataType, as) -> pure $ DataTypeCons is_type_data (handle_type_data as) (NewType, as) -> addFatalError $ mkPlainErrorMsgEnvelope span $ PsErrMultipleConForNewtype name (length as) where -- In a "type data" declaration, the constructors are in the type/class -- namespace rather than the data constructor namespace. -- See Note [Type data declarations] in GHC.Rename.Module. handle_type_data | is_type_data = map (fmap promote_constructor) | otherwise = id promote_constructor (dc@ConDeclGADT { con_names = cons }) = dc { con_names = fmap (fmap promote_name) cons } promote_constructor (dc@ConDeclH98 { con_name = con }) = dc { con_name = fmap promote_name con } promote_constructor dc = dc promote_name name = fromMaybe name (promoteRdrName name) ----------------------------------------------------------------------------- -- utilities for foreign declarations -- construct a foreign import declaration -- mkImport :: Located CCallConv -> Located Safety -> (Located StringLiteral, LocatedN RdrName, LHsSigType GhcPs) -> (EpToken "import", TokDcolon) -> P (EpToken "foreign" -> HsDecl GhcPs) mkImport cconv safety (L loc (StringLiteral esrc entity _), v, ty) (timport, td) = case unLoc cconv of CCallConv -> returnSpec =<< mkCImport CApiConv -> do imp <- mkCImport if isCWrapperImport imp then addFatalError $ mkPlainErrorMsgEnvelope loc PsErrInvalidCApiImport else returnSpec imp StdCallConv -> returnSpec =<< mkCImport PrimCallConv -> mkOtherImport JavaScriptCallConv -> mkOtherImport where -- Parse a C-like entity string of the following form: -- "[static] [chname] [&] [cid]" | "dynamic" | "wrapper" -- If 'cid' is missing, the function name 'v' is used instead as symbol -- name (cf section 8.5.1 in Haskell 2010 report). mkCImport = do let e = unpackFS entity case parseCImport (reLoc cconv) (reLoc safety) (mkExtName (unLoc v)) e (L loc esrc) of Nothing -> addFatalError $ mkPlainErrorMsgEnvelope loc $ PsErrMalformedEntityString Just importSpec -> return importSpec isCWrapperImport (CImport _ _ _ _ CWrapper) = True isCWrapperImport _ = False -- currently, all the other import conventions only support a symbol name in -- the entity string. If it is missing, we use the function name instead. mkOtherImport = returnSpec importSpec where entity' = if nullFS entity then mkExtName (unLoc v) else entity funcTarget = CFunction (StaticTarget esrc entity' Nothing True) importSpec = CImport (L (l2l loc) esrc) (reLoc cconv) (reLoc safety) Nothing funcTarget returnSpec spec = return $ \tforeign -> ForD noExtField $ ForeignImport { fd_i_ext = (tforeign, timport, td) , fd_name = v , fd_sig_ty = ty , fd_fi = spec } -- the string "foo" is ambiguous: either a header or a C identifier. The -- C identifier case comes first in the alternatives below, so we pick -- that one. parseCImport :: LocatedE CCallConv -> LocatedE Safety -> FastString -> String -> Located SourceText -> Maybe (ForeignImport (GhcPass p)) parseCImport cconv safety nm str sourceText = listToMaybe $ map fst $ filter (null.snd) $ readP_to_S parse str where parse = do skipSpaces r <- choice [ string "dynamic" >> return (mk Nothing (CFunction DynamicTarget)), string "wrapper" >> return (mk Nothing CWrapper), do optional (token "static" >> skipSpaces) ((mk Nothing <$> cimp nm) +++ (do h <- munch1 hdr_char skipSpaces let src = mkFastString h mk (Just (Header (SourceText src) src)) <$> cimp nm)) ] skipSpaces return r token str = do _ <- string str toks <- look case toks of c : _ | id_char c -> pfail _ -> return () mk h n = CImport (reLoc sourceText) (reLoc cconv) (reLoc safety) h n hdr_char c = not (isSpace c) -- header files are filenames, which can contain -- pretty much any char (depending on the platform), -- so just accept any non-space character id_first_char c = isAlpha c || c == '_' id_char c = isAlphaNum c || c == '_' cimp nm = (ReadP.char '&' >> skipSpaces >> CLabel <$> cid) +++ (do isFun <- case unLoc cconv of CApiConv -> option True (do token "value" skipSpaces return False) _ -> return True cid' <- cid return (CFunction (StaticTarget NoSourceText cid' Nothing isFun))) where cid = return nm +++ (do c <- satisfy id_first_char cs <- many (satisfy id_char) return (mkFastString (c:cs))) -- construct a foreign export declaration -- mkExport :: Located CCallConv -> (Located StringLiteral, LocatedN RdrName, LHsSigType GhcPs) -> ( EpToken "export", TokDcolon) -> P (EpToken "foreign" -> HsDecl GhcPs) mkExport (L lc cconv) (L le (StringLiteral esrc entity _), v, ty) (texport, td) = return $ \tforeign -> ForD noExtField $ ForeignExport { fd_e_ext = (tforeign, texport, td), fd_name = v, fd_sig_ty = ty , fd_fe = CExport (L (l2l le) esrc) (L (l2l lc) (CExportStatic esrc entity' cconv)) } where entity' | nullFS entity = mkExtName (unLoc v) | otherwise = entity -- Supplying the ext_name in a foreign decl is optional; if it -- isn't there, the Haskell name is assumed. Note that no transformation -- of the Haskell name is then performed, so if you foreign export (++), -- it's external name will be "++". Too bad; it's important because we don't -- want z-encoding (e.g. names with z's in them shouldn't be doubled) -- mkExtName :: RdrName -> CLabelString mkExtName rdrNm = occNameFS (rdrNameOcc rdrNm) -------------------------------------------------------------------------------- -- Help with module system imports/exports data ImpExpSubSpec = ImpExpAbs | ImpExpAll (EpToken "..") | ImpExpList [LocatedA ImpExpQcSpec] | ImpExpAllWith [LocatedA ImpExpQcSpec] data ImpExpQcSpec = ImpExpQcName (LocatedN RdrName) | ImpExpQcType (EpToken "type") (LocatedN RdrName) | ImpExpQcWildcard (EpToken "..") (EpToken ",") mkModuleImpExp :: Maybe (LWarningTxt GhcPs) -> (EpToken "(", EpToken ")") -> LocatedA ImpExpQcSpec -> ImpExpSubSpec -> P (IE GhcPs) mkModuleImpExp warning (top, tcp) (L l specname) subs = do case subs of ImpExpAbs | isVarNameSpace (rdrNameSpace name) -> return $ IEVar warning (L l (ieNameFromSpec specname)) Nothing | otherwise -> IEThingAbs warning . L l <$> nameT <*> pure noExportDoc ImpExpAll tok -> IEThingAll (warning, (top, tok, tcp)) . L l <$> nameT <*> pure noExportDoc ImpExpList xs -> (\newName -> IEThingWith (warning, (top,NoEpTok,NoEpTok,tcp)) (L l newName) NoIEWildcard (wrapped xs)) <$> nameT <*> pure noExportDoc ImpExpAllWith xs -> do allowed <- getBit PatternSynonymsBit if allowed then let withs = map unLoc xs pos = maybe NoIEWildcard IEWildcard (findIndex isImpExpQcWildcard withs) (td,tc) = case find isImpExpQcWildcard withs of Just (ImpExpQcWildcard td tc) -> (td,tc) _ -> (NoEpTok, NoEpTok) ies :: [LocatedA (IEWrappedName GhcPs)] ies = wrapped $ filter (not . isImpExpQcWildcard . unLoc) xs in (\newName -> IEThingWith (warning, (top,td,tc,tcp)) (L l newName) pos ies) <$> nameT <*> pure noExportDoc else addFatalError $ mkPlainErrorMsgEnvelope (locA l) $ PsErrIllegalPatSynExport where noExportDoc :: Maybe (LHsDoc GhcPs) noExportDoc = Nothing name = ieNameVal specname nameT = if isVarNameSpace (rdrNameSpace name) then addFatalError $ mkPlainErrorMsgEnvelope (locA l) $ (PsErrVarForTyCon name) else return $ ieNameFromSpec specname ieNameVal (ImpExpQcName ln) = unLoc ln ieNameVal (ImpExpQcType _ ln) = unLoc ln ieNameVal ImpExpQcWildcard{} = panic "ieNameVal got wildcard" ieNameFromSpec :: ImpExpQcSpec -> IEWrappedName GhcPs ieNameFromSpec (ImpExpQcName (L l n)) = IEName noExtField (L l n) ieNameFromSpec (ImpExpQcType r (L l n)) = IEType r (L l n) ieNameFromSpec ImpExpQcWildcard{} = panic "ieName got wildcard" wrapped = map (fmap ieNameFromSpec) mkTypeImpExp :: LocatedN RdrName -- TcCls or Var name space -> P (LocatedN RdrName) mkTypeImpExp name = do requireExplicitNamespaces (getLocA name) return (fmap (`setRdrNameSpace` tcClsName) name) checkImportSpec :: LocatedLI [LIE GhcPs] -> P (LocatedLI [LIE GhcPs]) checkImportSpec ie@(L _ specs) = case [l | (L l (IEThingWith _ _ (IEWildcard _) _ _)) <- specs] of [] -> return ie (l:_) -> importSpecError (locA l) where importSpecError l = addFatalError $ mkPlainErrorMsgEnvelope l PsErrIllegalImportBundleForm -- In the correct order mkImpExpSubSpec :: [LocatedA ImpExpQcSpec] -> P ImpExpSubSpec mkImpExpSubSpec [] = return (ImpExpList []) mkImpExpSubSpec [L _ (ImpExpQcWildcard td _tc)] = return (ImpExpAll td) mkImpExpSubSpec xs = if (any (isImpExpQcWildcard . unLoc) xs) then return $ (ImpExpAllWith xs) else return $ (ImpExpList xs) isImpExpQcWildcard :: ImpExpQcSpec -> Bool isImpExpQcWildcard (ImpExpQcWildcard _ _) = True isImpExpQcWildcard _ = False ----------------------------------------------------------------------------- -- Warnings and failures warnPrepositiveQualifiedModule :: SrcSpan -> P () warnPrepositiveQualifiedModule span = addPsMessage span PsWarnImportPreQualified failNotEnabledImportQualifiedPost :: SrcSpan -> P () failNotEnabledImportQualifiedPost loc = addError $ mkPlainErrorMsgEnvelope loc $ PsErrImportPostQualified failImportQualifiedTwice :: SrcSpan -> P () failImportQualifiedTwice loc = addError $ mkPlainErrorMsgEnvelope loc $ PsErrImportQualifiedTwice warnStarIsType :: SrcSpan -> P () warnStarIsType span = addPsMessage span PsWarnStarIsType failOpFewArgs :: MonadP m => LocatedN RdrName -> m a failOpFewArgs (L loc op) = do { star_is_type <- getBit StarIsTypeBit ; let is_star_type = if star_is_type then StarIsType else StarIsNotType ; addFatalError $ mkPlainErrorMsgEnvelope (locA loc) $ (PsErrOpFewArgs is_star_type op) } requireExplicitNamespaces :: MonadP m => SrcSpan -> m () requireExplicitNamespaces l = do allowed <- getBit ExplicitNamespacesBit unless allowed $ addError $ mkPlainErrorMsgEnvelope l PsErrIllegalExplicitNamespace ----------------------------------------------------------------------------- -- Misc utils data PV_Context = PV_Context { pv_options :: ParserOpts , pv_details :: ParseContext -- See Note [Parser-Validator Details] } data PV_Accum = PV_Accum { pv_warnings :: Messages PsMessage , pv_errors :: Messages PsMessage , pv_header_comments :: Strict.Maybe [LEpaComment] , pv_comment_q :: [LEpaComment] } data PV_Result a = PV_Ok PV_Accum a | PV_Failed PV_Accum deriving (Foldable, Functor, Traversable) -- During parsing, we make use of several monadic effects: reporting parse errors, -- accumulating warnings, adding API annotations, and checking for extensions. These -- effects are captured by the 'MonadP' type class. -- -- Sometimes we need to postpone some of these effects to a later stage due to -- ambiguities described in Note [Ambiguous syntactic categories]. -- We could use two layers of the P monad, one for each stage: -- -- abParser :: forall x. DisambAB x => P (P x) -- -- The outer layer of P consumes the input and builds the inner layer, which -- validates the input. But this type is not particularly helpful, as it obscures -- the fact that the inner layer of P never consumes any input. -- -- For clarity, we introduce the notion of a parser-validator: a parser that does -- not consume any input, but may fail or use other effects. Thus we have: -- -- abParser :: forall x. DisambAB x => P (PV x) -- newtype PV a = PV { unPV :: PV_Context -> PV_Accum -> PV_Result a } deriving (Functor) instance Applicative PV where pure a = a `seq` PV (\_ acc -> PV_Ok acc a) (<*>) = ap instance Monad PV where m >>= f = PV $ \ctx acc -> case unPV m ctx acc of PV_Ok acc' a -> unPV (f a) ctx acc' PV_Failed acc' -> PV_Failed acc' runPV :: PV a -> P a runPV = runPV_details noParseContext askParseContext :: PV ParseContext askParseContext = PV $ \(PV_Context _ details) acc -> PV_Ok acc details runPV_details :: ParseContext -> PV a -> P a runPV_details details m = P $ \s -> let pv_ctx = PV_Context { pv_options = options s , pv_details = details } pv_acc = PV_Accum { pv_warnings = warnings s , pv_errors = errors s , pv_header_comments = header_comments s , pv_comment_q = comment_q s } mkPState acc' = s { warnings = pv_warnings acc' , errors = pv_errors acc' , comment_q = pv_comment_q acc' } in case unPV m pv_ctx pv_acc of PV_Ok acc' a -> POk (mkPState acc') a PV_Failed acc' -> PFailed (mkPState acc') instance MonadP PV where addError err = PV $ \_ctx acc -> PV_Ok acc{pv_errors = err `addMessage` pv_errors acc} () addWarning w = PV $ \_ctx acc -> -- No need to check for the warning flag to be set, GHC will correctly discard suppressed -- diagnostics. PV_Ok acc{pv_warnings= w `addMessage` pv_warnings acc} () addFatalError err = addError err >> PV (const PV_Failed) getParserOpts = PV $ \ctx acc -> PV_Ok acc $! pv_options ctx allocateCommentsP ss = PV $ \_ s -> if null (pv_comment_q s) then PV_Ok s emptyComments else -- fast path let (comment_q', newAnns) = allocateComments ss (pv_comment_q s) in PV_Ok s { pv_comment_q = comment_q' } (EpaComments newAnns) allocatePriorCommentsP ss = PV $ \_ s -> let (header_comments', comment_q', newAnns) = allocatePriorComments ss (pv_comment_q s) (pv_header_comments s) in PV_Ok s { pv_header_comments = header_comments', pv_comment_q = comment_q' } (EpaComments newAnns) allocateFinalCommentsP ss = PV $ \_ s -> let (header_comments', comment_q', newAnns) = allocateFinalComments ss (pv_comment_q s) (pv_header_comments s) in PV_Ok s { pv_header_comments = header_comments', pv_comment_q = comment_q' } (EpaCommentsBalanced (Strict.fromMaybe [] header_comments') newAnns) {- Note [Parser-Validator Details] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ A PV computation is parameterized by some 'ParseContext' for diagnostic messages, which can be set depending on validation context. We use this in checkPattern to fix #984. Consider this example, where the user has forgotten a 'do': f _ = do x <- computation case () of _ -> result <- computation case () of () -> undefined GHC parses it as follows: f _ = do x <- computation (case () of _ -> result) <- computation case () of () -> undefined Note that this fragment is parsed as a pattern: case () of _ -> result We attempt to detect such cases and add a hint to the diagnostic messages: T984.hs:6:9: Parse error in pattern: case () of { _ -> result } Possibly caused by a missing 'do'? The "Possibly caused by a missing 'do'?" suggestion is the hint that is computed out of the 'ParseContext', which are read by functions like 'patFail' when constructing the 'PsParseErrorInPatDetails' data structure. When validating in a context other than 'bindpat' (a pattern to the left of <-), we set the details to 'noParseContext' and it has no effect on the diagnostic messages. -} -- | Hint about bang patterns, assuming @BangPatterns@ is off. hintBangPat :: SrcSpan -> Pat GhcPs -> PV () hintBangPat span e = do bang_on <- getBit BangPatBit unless bang_on $ addError $ mkPlainErrorMsgEnvelope span $ PsErrIllegalBangPattern e mkSumOrTupleExpr :: SrcSpanAnnA -> Boxity -> SumOrTuple (HsExpr GhcPs) -> (EpaLocation, EpaLocation) -> PV (LHsExpr GhcPs) -- Tuple mkSumOrTupleExpr l@(EpAnn anc an csIn) boxity (Tuple es) anns = do !cs <- getCommentsFor (locA l) return $ L (EpAnn anc an (csIn Semi.<> cs)) (ExplicitTuple anns (map toTupArg es) boxity) where toTupArg :: Either (EpAnn Bool) (LHsExpr GhcPs) -> HsTupArg GhcPs toTupArg (Left ann) = missingTupArg ann toTupArg (Right a) = Present noExtField a -- Sum -- mkSumOrTupleExpr l Unboxed (Sum alt arity e) = -- return $ L l (ExplicitSum noExtField alt arity e) mkSumOrTupleExpr l@(EpAnn anc anIn csIn) Unboxed (Sum alt arity e barsp barsa) (o, c) = do let an = AnnExplicitSum o barsp barsa c !cs <- getCommentsFor (locA l) return $ L (EpAnn anc anIn (csIn Semi.<> cs)) (ExplicitSum an alt arity e) mkSumOrTupleExpr l Boxed a@Sum{} _ = addFatalError $ mkPlainErrorMsgEnvelope (locA l) $ PsErrUnsupportedBoxedSumExpr a mkSumOrTuplePat :: SrcSpanAnnA -> Boxity -> SumOrTuple (PatBuilder GhcPs) -> (EpaLocation, EpaLocation) -> PV (LocatedA (PatBuilder GhcPs)) -- Tuple mkSumOrTuplePat l boxity (Tuple ps) anns = do ps' <- traverse toTupPat ps return $ L l (PatBuilderPat (TuplePat anns ps' boxity)) where toTupPat :: Either (EpAnn Bool) (LocatedA (PatBuilder GhcPs)) -> PV (LPat GhcPs) -- Ignore the element location so that the error message refers to the -- entire tuple. See #19504 (and the discussion) for details. toTupPat p = case p of Left _ -> addFatalError $ mkPlainErrorMsgEnvelope (locA l) PsErrTupleSectionInPat Right p' -> checkLPat p' -- Sum mkSumOrTuplePat l Unboxed (Sum alt arity p barsb barsa) anns = do p' <- checkLPat p let an = EpAnnSumPat anns barsb barsa return $ L l (PatBuilderPat (SumPat an p' alt arity)) mkSumOrTuplePat l Boxed a@Sum{} _ = addFatalError $ mkPlainErrorMsgEnvelope (locA l) $ PsErrUnsupportedBoxedSumPat a mkLHsOpTy :: PromotionFlag -> LHsType GhcPs -> LocatedN RdrName -> LHsType GhcPs -> LHsType GhcPs mkLHsOpTy prom x op y = let loc = locA x `combineSrcSpans` locA op `combineSrcSpans` locA y in L (noAnnSrcSpan loc) (mkHsOpTy prom x op y) mkMultTy :: EpToken "%" -> LHsType GhcPs -> TokRarrow -> HsArrow GhcPs mkMultTy pct t@(L _ (HsTyLit _ (HsNumTy (SourceText (unpackFS -> "1")) 1))) arr -- See #18888 for the use of (SourceText "1") above = HsLinearArrow (EpPct1 pct1 arr) where -- The location of "%" combined with the location of "1". pct1 :: EpToken "%1" pct1 = epTokenWidenR pct (locA (getLoc t)) mkMultTy pct t arr = HsExplicitMult (pct, arr) t mkMultExpr :: EpToken "%" -> LHsExpr GhcPs -> TokRarrow -> HsArrowOf (LHsExpr GhcPs) GhcPs mkMultExpr pct t@(L _ (HsOverLit _ (OverLit _ (HsIntegral (IL (SourceText (unpackFS -> "1")) _ 1))))) arr -- See #18888 for the use of (SourceText "1") above = HsLinearArrow (EpPct1 pct1 arr) where -- The location of "%" combined with the location of "1". pct1 :: EpToken "%1" pct1 = epTokenWidenR pct (locA (getLoc t)) mkMultExpr pct t arr = HsExplicitMult (pct, arr) t mkMultAnn :: EpToken "%" -> LHsType GhcPs -> HsMultAnn GhcPs mkMultAnn pct t@(L _ (HsTyLit _ (HsNumTy (SourceText (unpackFS -> "1")) 1))) -- See #18888 for the use of (SourceText "1") above = HsPct1Ann pct1 where -- The location of "%" combined with the location of "1". pct1 :: EpToken "%1" pct1 = epTokenWidenR pct (locA (getLoc t)) mkMultAnn pct t = HsMultAnn pct t mkTokenLocation :: SrcSpan -> TokenLocation mkTokenLocation (UnhelpfulSpan _) = NoTokenLoc mkTokenLocation (RealSrcSpan r mb) = TokenLoc (EpaSpan (RealSrcSpan r mb)) -- Precondition: the EpToken has EpaSpan, never EpaDelta. epTokenWidenR :: EpToken tok -> SrcSpan -> EpToken tok' epTokenWidenR NoEpTok _ = NoEpTok epTokenWidenR (EpTok l) (UnhelpfulSpan _) = EpTok l epTokenWidenR (EpTok (EpaSpan s1)) s2 = EpTok (EpaSpan (combineSrcSpans s1 s2)) epTokenWidenR (EpTok EpaDelta{}) _ = -- Never happens because the parser does not produce EpaDelta. panic "epTokenWidenR: EpaDelta" ----------------------------------------------------------------------------- -- Token symbols starSym :: Bool -> FastString starSym True = fsLit "★" starSym False = fsLit "*" ----------------------------------------- -- Bits and pieces for RecordDotSyntax. mkRdrGetField :: LHsExpr GhcPs -> LocatedAn NoEpAnns (DotFieldOcc GhcPs) -> HsExpr GhcPs mkRdrGetField arg field = HsGetField { gf_ext = NoExtField , gf_expr = arg , gf_field = field } mkRdrProjection :: NonEmpty (LocatedAn NoEpAnns (DotFieldOcc GhcPs)) -> AnnProjection -> HsExpr GhcPs mkRdrProjection flds anns = HsProjection { proj_ext = anns , proj_flds = fmap unLoc flds } mkRdrProjUpdate :: SrcSpanAnnA -> Located [LocatedAn NoEpAnns (DotFieldOcc GhcPs)] -> LHsExpr GhcPs -> Bool -> Maybe (EpToken "=") -> LHsRecProj GhcPs (LHsExpr GhcPs) mkRdrProjUpdate _ (L _ []) _ _ _ = panic "mkRdrProjUpdate: The impossible has happened!" mkRdrProjUpdate loc (L l flds) arg isPun anns = L loc HsFieldBind { hfbAnn = anns , hfbLHS = L (noAnnSrcSpan l) (FieldLabelStrings flds) , hfbRHS = arg , hfbPun = isPun } ----------------------------------------------------------------------------- -- Tuple and list punning punsAllowed :: P Bool punsAllowed = getBit ListTuplePunsBit -- | Check whether @ListTuplePuns@ is enabled and return the first arg if it is, -- the second arg otherwise. punsIfElse :: a -> a -> P a punsIfElse enabled disabled = do allowed <- punsAllowed pure (if allowed then enabled else disabled) -- | Emit an error of type 'PsErrInvalidPun' with a location from @start@ to -- @end@ if the extension @ListTuplePuns@ is disabled. -- -- This is used in Parser.y to guard rules that require punning. requireLTPuns :: PsErrPunDetails -> Located a -> Located b -> P () requireLTPuns err start end = unlessM punsAllowed $ do addError (mkPlainErrorMsgEnvelope loc (PsErrInvalidPun err)) where loc = (combineSrcSpans (getLoc start) (getLoc end)) -- | Call a parser with a span and its comments given by a start and end token. withCombinedComments :: HasLoc l1 => HasLoc l2 => l1 -> l2 -> (SrcSpan -> P a) -> P (LocatedA a) withCombinedComments start end use = do cs <- getCommentsFor fullSpan a <- use fullSpan pure (L (EpAnn (spanAsAnchor fullSpan) noAnn cs) a) where fullSpan = combineSrcSpans (getHasLoc start) (getHasLoc end) -- | Decide whether to parse tuple syntax @(Int, Double)@ in a type as a -- type or data constructor, based on the extension @ListTuplePuns@. -- The case with an explicit promotion quote, @'(Int, Double)@, is handled -- by 'mkExplicitTupleTy'. mkTupleSyntaxTy :: EpToken "(" -> [LocatedA (HsType GhcPs)] -> EpToken ")" -> P (HsType GhcPs) mkTupleSyntaxTy parOpen args parClose = punsIfElse enabled disabled where enabled = HsTupleTy annParen HsBoxedOrConstraintTuple args disabled = HsExplicitTupleTy annsKeyword NotPromoted args annParen = AnnParens parOpen parClose annsKeyword = (NoEpTok, parOpen, parClose) -- | Decide whether to parse tuple con syntax @(,)@ in a type as a -- type or data constructor, based on the extension @ListTuplePuns@. -- The case with an explicit promotion quote, @'(,)@, is handled -- by the rule @SIMPLEQUOTE sysdcon_nolist@ in @atype@. mkTupleSyntaxTycon :: Boxity -> Int -> P RdrName mkTupleSyntaxTycon boxity n = punsIfElse (getRdrName (tupleTyCon boxity n)) (getRdrName (tupleDataCon boxity n)) -- | Decide whether to parse list tycon syntax @[]@ in a type as a type or data -- constructor, based on the extension @ListTuplePuns@. -- The case with an explicit promotion quote, @'[]@, is handled by -- 'mkExplicitListTy'. mkListSyntaxTy0 :: EpToken "[" -> EpToken "]" -> SrcSpan -> P (HsType GhcPs) mkListSyntaxTy0 brkOpen brkClose span = punsIfElse enabled disabled where enabled = HsTyVar noAnn NotPromoted rn -- attach the comments only to the RdrName since it's the innermost AST node rn = L (EpAnn fullLoc rdrNameAnn emptyComments) listTyCon_RDR disabled = HsExplicitListTy annsKeyword NotPromoted [] rdrNameAnn = NameAnnOnly (NameSquare brkOpen brkClose) [] annsKeyword = (NoEpTok, brkOpen, brkClose) fullLoc = EpaSpan span -- | Decide whether to parse list type syntax @[Int]@ in a type as a -- type or data constructor, based on the extension @ListTuplePuns@. -- The case with an explicit promotion quote, @'[Int]@, is handled -- by 'mkExplicitListTy'. mkListSyntaxTy1 :: EpToken "[" -> LocatedA (HsType GhcPs) -> EpToken "]" -> P (HsType GhcPs) mkListSyntaxTy1 brkOpen t brkClose = punsIfElse enabled disabled where enabled = HsListTy annParen t disabled = HsExplicitListTy annsKeyword NotPromoted [t] annsKeyword = (NoEpTok, brkOpen, brkClose) annParen = AnnParensSquare brkOpen brkClose