{- (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 \section[RnPat]{Renaming of patterns} Basically dependency analysis. Handles @Match@, @GRHSs@, @HsExpr@, and @Qualifier@ datatypes. In general, all of these functions return a renamed thing, and a set of free variables. -} {-# LANGUAGE CPP, RankNTypes, ScopedTypeVariables #-} module RnPat (-- main entry points rnPat, rnPats, rnBindPat, rnPatAndThen, NameMaker, applyNameMaker, -- a utility for making names: localRecNameMaker, topRecNameMaker, -- sometimes we want to make local names, -- sometimes we want to make top (qualified) names. isTopRecNameMaker, rnHsRecFields, HsRecFieldContext(..), rnHsRecUpdFields, -- CpsRn monad CpsRn, liftCps, -- Literals rnLit, rnOverLit, -- Pattern Error messages that are also used elsewhere checkTupSize, patSigErr ) where -- ENH: thin imports to only what is necessary for patterns import GhcPrelude import {-# SOURCE #-} RnExpr ( rnLExpr ) import {-# SOURCE #-} RnSplice ( rnSplicePat ) #include "HsVersions.h" import HsSyn import TcRnMonad import TcHsSyn ( hsOverLitName ) import RnEnv import RnFixity import RnUtils ( HsDocContext(..), newLocalBndrRn, bindLocalNames , warnUnusedMatches, newLocalBndrRn , checkDupNames, checkDupAndShadowedNames , checkTupSize , unknownSubordinateErr ) import RnUnbound ( mkUnboundName ) import RnTypes import PrelNames import TyCon ( tyConName ) import ConLike import Type ( TyThing(..) ) import Name import NameSet import OccName ( setOccNameSpace, tcName ) import RdrName import BasicTypes import Util import ListSetOps ( removeDups ) import Outputable import SrcLoc import Literal ( inCharRange ) import TysWiredIn ( nilDataCon ) import DataCon import qualified GHC.LanguageExtensions as LangExt import Control.Monad ( when, liftM, ap ) import qualified Data.List.NonEmpty as NE import Data.Ratio {- ********************************************************* * * The CpsRn Monad * * ********************************************************* Note [CpsRn monad] ~~~~~~~~~~~~~~~~~~ The CpsRn monad uses continuation-passing style to support this style of programming: do { ... ; ns <- bindNames rs ; ...blah... } where rs::[RdrName], ns::[Name] The idea is that '...blah...' a) sees the bindings of ns b) returns the free variables it mentions so that bindNames can report unused ones In particular, mapM rnPatAndThen [p1, p2, p3] has a *left-to-right* scoping: it makes the binders in p1 scope over p2,p3. -} newtype CpsRn b = CpsRn { unCpsRn :: forall r. (b -> RnM (r, FreeVars)) -> RnM (r, FreeVars) } -- See Note [CpsRn monad] instance Functor CpsRn where fmap = liftM instance Applicative CpsRn where pure x = CpsRn (\k -> k x) (<*>) = ap instance Monad CpsRn where (CpsRn m) >>= mk = CpsRn (\k -> m (\v -> unCpsRn (mk v) k)) runCps :: CpsRn a -> RnM (a, FreeVars) runCps (CpsRn m) = m (\r -> return (r, emptyFVs)) liftCps :: RnM a -> CpsRn a liftCps rn_thing = CpsRn (\k -> rn_thing >>= k) liftCpsFV :: RnM (a, FreeVars) -> CpsRn a liftCpsFV rn_thing = CpsRn (\k -> do { (v,fvs1) <- rn_thing ; (r,fvs2) <- k v ; return (r, fvs1 `plusFV` fvs2) }) wrapSrcSpanCps :: (a -> CpsRn b) -> Located a -> CpsRn (Located b) -- Set the location, and also wrap it around the value returned wrapSrcSpanCps fn (L loc a) = CpsRn (\k -> setSrcSpan loc $ unCpsRn (fn a) $ \v -> k (L loc v)) lookupConCps :: Located RdrName -> CpsRn (Located Name) lookupConCps con_rdr = CpsRn (\k -> do { con_name <- lookupLocatedOccRn con_rdr ; (r, fvs) <- k con_name ; return (r, addOneFV fvs (unLoc con_name)) }) -- We add the constructor name to the free vars -- See Note [Patterns are uses] {- Note [Patterns are uses] ~~~~~~~~~~~~~~~~~~~~~~~~ Consider module Foo( f, g ) where data T = T1 | T2 f T1 = True f T2 = False g _ = T1 Arguably we should report T2 as unused, even though it appears in a pattern, because it never occurs in a constructed position. See Trac #7336. However, implementing this in the face of pattern synonyms would be less straightforward, since given two pattern synonyms pattern P1 <- P2 pattern P2 <- () we need to observe the dependency between P1 and P2 so that type checking can be done in the correct order (just like for value bindings). Dependencies between bindings is analyzed in the renamer, where we don't know yet whether P2 is a constructor or a pattern synonym. So for now, we do report conid occurrences in patterns as uses. ********************************************************* * * Name makers * * ********************************************************* Externally abstract type of name makers, which is how you go from a RdrName to a Name -} data NameMaker = LamMk -- Lambdas Bool -- True <=> report unused bindings -- (even if True, the warning only comes out -- if -Wunused-matches is on) | LetMk -- Let bindings, incl top level -- Do *not* check for unused bindings TopLevelFlag MiniFixityEnv topRecNameMaker :: MiniFixityEnv -> NameMaker topRecNameMaker fix_env = LetMk TopLevel fix_env isTopRecNameMaker :: NameMaker -> Bool isTopRecNameMaker (LetMk TopLevel _) = True isTopRecNameMaker _ = False localRecNameMaker :: MiniFixityEnv -> NameMaker localRecNameMaker fix_env = LetMk NotTopLevel fix_env matchNameMaker :: HsMatchContext a -> NameMaker matchNameMaker ctxt = LamMk report_unused where -- Do not report unused names in interactive contexts -- i.e. when you type 'x <- e' at the GHCi prompt report_unused = case ctxt of StmtCtxt GhciStmtCtxt -> False -- also, don't warn in pattern quotes, as there -- is no RHS where the variables can be used! ThPatQuote -> False _ -> True rnHsSigCps :: LHsSigWcType GhcPs -> CpsRn (LHsSigWcType GhcRn) rnHsSigCps sig = CpsRn (rnHsSigWcTypeScoped PatCtx sig) newPatLName :: NameMaker -> Located RdrName -> CpsRn (Located Name) newPatLName name_maker rdr_name@(L loc _) = do { name <- newPatName name_maker rdr_name ; return (L loc name) } newPatName :: NameMaker -> Located RdrName -> CpsRn Name newPatName (LamMk report_unused) rdr_name = CpsRn (\ thing_inside -> do { name <- newLocalBndrRn rdr_name ; (res, fvs) <- bindLocalNames [name] (thing_inside name) ; when report_unused $ warnUnusedMatches [name] fvs ; return (res, name `delFV` fvs) }) newPatName (LetMk is_top fix_env) rdr_name = CpsRn (\ thing_inside -> do { name <- case is_top of NotTopLevel -> newLocalBndrRn rdr_name TopLevel -> newTopSrcBinder rdr_name ; bindLocalNames [name] $ -- Do *not* use bindLocalNameFV here -- See Note [View pattern usage] addLocalFixities fix_env [name] $ thing_inside name }) -- Note: the bindLocalNames is somewhat suspicious -- because it binds a top-level name as a local name. -- however, this binding seems to work, and it only exists for -- the duration of the patterns and the continuation; -- then the top-level name is added to the global env -- before going on to the RHSes (see RnSource.hs). {- Note [View pattern usage] ~~~~~~~~~~~~~~~~~~~~~~~~~ Consider let (r, (r -> x)) = x in ... Here the pattern binds 'r', and then uses it *only* in the view pattern. We want to "see" this use, and in let-bindings we collect all uses and report unused variables at the binding level. So we must use bindLocalNames here, *not* bindLocalNameFV. Trac #3943. Note [Don't report shadowing for pattern synonyms] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ There is one special context where a pattern doesn't introduce any new binders - pattern synonym declarations. Therefore we don't check to see if pattern variables shadow existing identifiers as they are never bound to anything and have no scope. Without this check, there would be quite a cryptic warning that the `x` in the RHS of the pattern synonym declaration shadowed the top level `x`. ``` x :: () x = () pattern P x = Just x ``` See #12615 for some more examples. ********************************************************* * * External entry points * * ********************************************************* There are various entry points to renaming patterns, depending on (1) whether the names created should be top-level names or local names (2) whether the scope of the names is entirely given in a continuation (e.g., in a case or lambda, but not in a let or at the top-level, because of the way mutually recursive bindings are handled) (3) whether the a type signature in the pattern can bind lexically-scoped type variables (for unpacking existential type vars in data constructors) (4) whether we do duplicate and unused variable checking (5) whether there are fixity declarations associated with the names bound by the patterns that need to be brought into scope with them. Rather than burdening the clients of this module with all of these choices, we export the three points in this design space that we actually need: -} -- ----------- Entry point 1: rnPats ------------------- -- Binds local names; the scope of the bindings is entirely in the thing_inside -- * allows type sigs to bind type vars -- * local namemaker -- * unused and duplicate checking -- * no fixities rnPats :: HsMatchContext Name -- for error messages -> [LPat GhcPs] -> ([LPat GhcRn] -> RnM (a, FreeVars)) -> RnM (a, FreeVars) rnPats ctxt pats thing_inside = do { envs_before <- getRdrEnvs -- (1) rename the patterns, bringing into scope all of the term variables -- (2) then do the thing inside. ; unCpsRn (rnLPatsAndThen (matchNameMaker ctxt) pats) $ \ pats' -> do { -- Check for duplicated and shadowed names -- Must do this *after* renaming the patterns -- See Note [Collect binders only after renaming] in HsUtils -- Because we don't bind the vars all at once, we can't -- check incrementally for duplicates; -- Nor can we check incrementally for shadowing, else we'll -- complain *twice* about duplicates e.g. f (x,x) = ... -- -- See note [Don't report shadowing for pattern synonyms] ; let bndrs = collectPatsBinders pats' ; addErrCtxt doc_pat $ if isPatSynCtxt ctxt then checkDupNames bndrs else checkDupAndShadowedNames envs_before bndrs ; thing_inside pats' } } where doc_pat = text "In" <+> pprMatchContext ctxt rnPat :: HsMatchContext Name -- for error messages -> LPat GhcPs -> (LPat GhcRn -> RnM (a, FreeVars)) -> RnM (a, FreeVars) -- Variables bound by pattern do not -- appear in the result FreeVars rnPat ctxt pat thing_inside = rnPats ctxt [pat] (\pats' -> let [pat'] = pats' in thing_inside pat') applyNameMaker :: NameMaker -> Located RdrName -> RnM (Located Name) applyNameMaker mk rdr = do { (n, _fvs) <- runCps (newPatLName mk rdr) ; return n } -- ----------- Entry point 2: rnBindPat ------------------- -- Binds local names; in a recursive scope that involves other bound vars -- e.g let { (x, Just y) = e1; ... } in ... -- * does NOT allows type sig to bind type vars -- * local namemaker -- * no unused and duplicate checking -- * fixities might be coming in rnBindPat :: NameMaker -> LPat GhcPs -> RnM (LPat GhcRn, FreeVars) -- Returned FreeVars are the free variables of the pattern, -- of course excluding variables bound by this pattern rnBindPat name_maker pat = runCps (rnLPatAndThen name_maker pat) {- ********************************************************* * * The main event * * ********************************************************* -} -- ----------- Entry point 3: rnLPatAndThen ------------------- -- General version: parametrized by how you make new names rnLPatsAndThen :: NameMaker -> [LPat GhcPs] -> CpsRn [LPat GhcRn] rnLPatsAndThen mk = mapM (rnLPatAndThen mk) -- Despite the map, the monad ensures that each pattern binds -- variables that may be mentioned in subsequent patterns in the list -------------------- -- The workhorse rnLPatAndThen :: NameMaker -> LPat GhcPs -> CpsRn (LPat GhcRn) rnLPatAndThen nm lpat = wrapSrcSpanCps (rnPatAndThen nm) lpat rnPatAndThen :: NameMaker -> Pat GhcPs -> CpsRn (Pat GhcRn) rnPatAndThen _ (WildPat _) = return (WildPat placeHolderType) rnPatAndThen mk (ParPat pat) = do { pat' <- rnLPatAndThen mk pat; return (ParPat pat') } rnPatAndThen mk (LazyPat pat) = do { pat' <- rnLPatAndThen mk pat; return (LazyPat pat') } rnPatAndThen mk (BangPat pat) = do { pat' <- rnLPatAndThen mk pat; return (BangPat pat') } rnPatAndThen mk (VarPat (L l rdr)) = do { loc <- liftCps getSrcSpanM ; name <- newPatName mk (L loc rdr) ; return (VarPat (L l name)) } -- we need to bind pattern variables for view pattern expressions -- (e.g. in the pattern (x, x -> y) x needs to be bound in the rhs of the tuple) rnPatAndThen mk (SigPatIn pat sig) -- When renaming a pattern type signature (e.g. f (a :: T) = ...), it is -- important to rename its type signature _before_ renaming the rest of the -- pattern, so that type variables are first bound by the _outermost_ pattern -- type signature they occur in. This keeps the type checker happy when -- pattern type signatures happen to be nested (#7827) -- -- f ((Just (x :: a) :: Maybe a) -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~^ `a' is first bound here -- ~~~~~~~~~~~~~~~^ the same `a' then used here = do { sig' <- rnHsSigCps sig ; pat' <- rnLPatAndThen mk pat ; return (SigPatIn pat' sig') } rnPatAndThen mk (LitPat lit) | HsString src s <- lit = do { ovlStr <- liftCps (xoptM LangExt.OverloadedStrings) ; if ovlStr then rnPatAndThen mk (mkNPat (noLoc (mkHsIsString src s placeHolderType)) Nothing) else normal_lit } | otherwise = normal_lit where normal_lit = do { liftCps (rnLit lit); return (LitPat (convertLit lit)) } rnPatAndThen _ (NPat (L l lit) mb_neg _eq _) = do { (lit', mb_neg') <- liftCpsFV $ rnOverLit lit ; mb_neg' -- See Note [Negative zero] <- let negative = do { (neg, fvs) <- lookupSyntaxName negateName ; return (Just neg, fvs) } positive = return (Nothing, emptyFVs) in liftCpsFV $ case (mb_neg , mb_neg') of (Nothing, Just _ ) -> negative (Just _ , Nothing) -> negative (Nothing, Nothing) -> positive (Just _ , Just _ ) -> positive ; eq' <- liftCpsFV $ lookupSyntaxName eqName ; return (NPat (L l lit') mb_neg' eq' placeHolderType) } rnPatAndThen mk (NPlusKPat rdr (L l lit) _ _ _ _) = do { new_name <- newPatName mk rdr ; (lit', _) <- liftCpsFV $ rnOverLit lit -- See Note [Negative zero] -- We skip negateName as -- negative zero doesn't make -- sense in n + k patterns ; minus <- liftCpsFV $ lookupSyntaxName minusName ; ge <- liftCpsFV $ lookupSyntaxName geName ; return (NPlusKPat (L (nameSrcSpan new_name) new_name) (L l lit') lit' ge minus placeHolderType) } -- The Report says that n+k patterns must be in Integral rnPatAndThen mk (AsPat rdr pat) = do { new_name <- newPatLName mk rdr ; pat' <- rnLPatAndThen mk pat ; return (AsPat new_name pat') } rnPatAndThen mk p@(ViewPat expr pat _ty) = do { liftCps $ do { vp_flag <- xoptM LangExt.ViewPatterns ; checkErr vp_flag (badViewPat p) } -- Because of the way we're arranging the recursive calls, -- this will be in the right context ; expr' <- liftCpsFV $ rnLExpr expr ; pat' <- rnLPatAndThen mk pat -- Note: at this point the PreTcType in ty can only be a placeHolder -- ; return (ViewPat expr' pat' ty) } ; return (ViewPat expr' pat' placeHolderType) } rnPatAndThen mk (ConPatIn con stuff) -- rnConPatAndThen takes care of reconstructing the pattern -- The pattern for the empty list needs to be replaced by an empty explicit list pattern when overloaded lists is turned on. = case unLoc con == nameRdrName (dataConName nilDataCon) of True -> do { ol_flag <- liftCps $ xoptM LangExt.OverloadedLists ; if ol_flag then rnPatAndThen mk (ListPat [] placeHolderType Nothing) else rnConPatAndThen mk con stuff} False -> rnConPatAndThen mk con stuff rnPatAndThen mk (ListPat pats _ _) = do { opt_OverloadedLists <- liftCps $ xoptM LangExt.OverloadedLists ; pats' <- rnLPatsAndThen mk pats ; case opt_OverloadedLists of True -> do { (to_list_name,_) <- liftCps $ lookupSyntaxName toListName ; return (ListPat pats' placeHolderType (Just (placeHolderType, to_list_name)))} False -> return (ListPat pats' placeHolderType Nothing) } rnPatAndThen mk (PArrPat pats _) = do { pats' <- rnLPatsAndThen mk pats ; return (PArrPat pats' placeHolderType) } rnPatAndThen mk (TuplePat pats boxed _) = do { liftCps $ checkTupSize (length pats) ; pats' <- rnLPatsAndThen mk pats ; return (TuplePat pats' boxed []) } rnPatAndThen mk (SumPat pat alt arity _) = do { pat <- rnLPatAndThen mk pat ; return (SumPat pat alt arity PlaceHolder) } -- If a splice has been run already, just rename the result. rnPatAndThen mk (SplicePat (HsSpliced mfs (HsSplicedPat pat))) = SplicePat . HsSpliced mfs . HsSplicedPat <$> rnPatAndThen mk pat rnPatAndThen mk (SplicePat splice) = do { eith <- liftCpsFV $ rnSplicePat splice ; case eith of -- See Note [rnSplicePat] in RnSplice Left not_yet_renamed -> rnPatAndThen mk not_yet_renamed Right already_renamed -> return already_renamed } rnPatAndThen _ pat = pprPanic "rnLPatAndThen" (ppr pat) -------------------- rnConPatAndThen :: NameMaker -> Located RdrName -- the constructor -> HsConPatDetails GhcPs -> CpsRn (Pat GhcRn) rnConPatAndThen mk con (PrefixCon pats) = do { con' <- lookupConCps con ; pats' <- rnLPatsAndThen mk pats ; return (ConPatIn con' (PrefixCon pats')) } rnConPatAndThen mk con (InfixCon pat1 pat2) = do { con' <- lookupConCps con ; pat1' <- rnLPatAndThen mk pat1 ; pat2' <- rnLPatAndThen mk pat2 ; fixity <- liftCps $ lookupFixityRn (unLoc con') ; liftCps $ mkConOpPatRn con' fixity pat1' pat2' } rnConPatAndThen mk con (RecCon rpats) = do { con' <- lookupConCps con ; rpats' <- rnHsRecPatsAndThen mk con' rpats ; return (ConPatIn con' (RecCon rpats')) } -------------------- rnHsRecPatsAndThen :: NameMaker -> Located Name -- Constructor -> HsRecFields GhcPs (LPat GhcPs) -> CpsRn (HsRecFields GhcRn (LPat GhcRn)) rnHsRecPatsAndThen mk (L _ con) hs_rec_fields@(HsRecFields { rec_dotdot = dd }) = do { flds <- liftCpsFV $ rnHsRecFields (HsRecFieldPat con) mkVarPat hs_rec_fields ; flds' <- mapM rn_field (flds `zip` [1..]) ; return (HsRecFields { rec_flds = flds', rec_dotdot = dd }) } where mkVarPat l n = VarPat (L l n) rn_field (L l fld, n') = do { arg' <- rnLPatAndThen (nested_mk dd mk n') (hsRecFieldArg fld) ; return (L l (fld { hsRecFieldArg = arg' })) } -- Suppress unused-match reporting for fields introduced by ".." nested_mk Nothing mk _ = mk nested_mk (Just _) mk@(LetMk {}) _ = mk nested_mk (Just n) (LamMk report_unused) n' = LamMk (report_unused && (n' <= n)) {- ************************************************************************ * * Record fields * * ************************************************************************ -} data HsRecFieldContext = HsRecFieldCon Name | HsRecFieldPat Name | HsRecFieldUpd rnHsRecFields :: forall arg. HsRecFieldContext -> (SrcSpan -> RdrName -> arg) -- When punning, use this to build a new field -> HsRecFields GhcPs (Located arg) -> RnM ([LHsRecField GhcRn (Located arg)], FreeVars) -- This surprisingly complicated pass -- a) looks up the field name (possibly using disambiguation) -- b) fills in puns and dot-dot stuff -- When we we've finished, we've renamed the LHS, but not the RHS, -- of each x=e binding -- -- This is used for record construction and pattern-matching, but not updates. rnHsRecFields ctxt mk_arg (HsRecFields { rec_flds = flds, rec_dotdot = dotdot }) = do { pun_ok <- xoptM LangExt.RecordPuns ; disambig_ok <- xoptM LangExt.DisambiguateRecordFields ; parent <- check_disambiguation disambig_ok mb_con ; flds1 <- mapM (rn_fld pun_ok parent) flds ; mapM_ (addErr . dupFieldErr ctxt) dup_flds ; dotdot_flds <- rn_dotdot dotdot mb_con flds1 ; let all_flds | null dotdot_flds = flds1 | otherwise = flds1 ++ dotdot_flds ; return (all_flds, mkFVs (getFieldIds all_flds)) } where mb_con = case ctxt of HsRecFieldCon con -> Just con HsRecFieldPat con -> Just con _ {- update -} -> Nothing doc = case mb_con of Nothing -> text "constructor field name" Just con -> text "field of constructor" <+> quotes (ppr con) rn_fld :: Bool -> Maybe Name -> LHsRecField GhcPs (Located arg) -> RnM (LHsRecField GhcRn (Located arg)) rn_fld pun_ok parent (L l (HsRecField { hsRecFieldLbl = L loc (FieldOcc (L ll lbl) _) , hsRecFieldArg = arg , hsRecPun = pun })) = do { sel <- setSrcSpan loc $ lookupRecFieldOcc parent doc lbl ; arg' <- if pun then do { checkErr pun_ok (badPun (L loc lbl)) -- Discard any module qualifier (#11662) ; let arg_rdr = mkRdrUnqual (rdrNameOcc lbl) ; return (L loc (mk_arg loc arg_rdr)) } else return arg ; return (L l (HsRecField { hsRecFieldLbl = L loc (FieldOcc (L ll lbl) sel) , hsRecFieldArg = arg' , hsRecPun = pun })) } rn_dotdot :: Maybe Int -- See Note [DotDot fields] in HsPat -> Maybe Name -- The constructor (Nothing for an -- out of scope constructor) -> [LHsRecField GhcRn (Located arg)] -- Explicit fields -> RnM [LHsRecField GhcRn (Located arg)] -- Filled in .. fields rn_dotdot (Just n) (Just con) flds -- ".." on record construction / pat match | not (isUnboundName con) -- This test is because if the constructor -- isn't in scope the constructor lookup will add -- an error but still return an unbound name. We -- don't want that to screw up the dot-dot fill-in stuff. = ASSERT( flds `lengthIs` n ) do { loc <- getSrcSpanM -- Rather approximate ; dd_flag <- xoptM LangExt.RecordWildCards ; checkErr dd_flag (needFlagDotDot ctxt) ; (rdr_env, lcl_env) <- getRdrEnvs ; con_fields <- lookupConstructorFields con ; when (null con_fields) (addErr (badDotDotCon con)) ; let present_flds = mkOccSet $ map rdrNameOcc (getFieldLbls flds) -- For constructor uses (but not patterns) -- the arg should be in scope locally; -- i.e. not top level or imported -- Eg. data R = R { x,y :: Int } -- f x = R { .. } -- Should expand to R {x=x}, not R{x=x,y=y} arg_in_scope lbl = mkRdrUnqual lbl `elemLocalRdrEnv` lcl_env (dot_dot_fields, dot_dot_gres) = unzip [ (fl, gre) | fl <- con_fields , let lbl = mkVarOccFS (flLabel fl) , not (lbl `elemOccSet` present_flds) , Just gre <- [lookupGRE_FieldLabel rdr_env fl] -- Check selector is in scope , case ctxt of HsRecFieldCon {} -> arg_in_scope lbl _other -> True ] ; addUsedGREs dot_dot_gres ; return [ L loc (HsRecField { hsRecFieldLbl = L loc (FieldOcc (L loc arg_rdr) sel) , hsRecFieldArg = L loc (mk_arg loc arg_rdr) , hsRecPun = False }) | fl <- dot_dot_fields , let sel = flSelector fl , let arg_rdr = mkVarUnqual (flLabel fl) ] } rn_dotdot _dotdot _mb_con _flds = return [] -- _dotdot = Nothing => No ".." at all -- _mb_con = Nothing => Record update -- _mb_con = Just unbound => Out of scope data constructor check_disambiguation :: Bool -> Maybe Name -> RnM (Maybe Name) -- When disambiguation is on, return name of parent tycon. check_disambiguation disambig_ok mb_con | disambig_ok, Just con <- mb_con = do { env <- getGlobalRdrEnv; return (find_tycon env con) } | otherwise = return Nothing find_tycon :: GlobalRdrEnv -> Name {- DataCon -} -> Maybe Name {- TyCon -} -- Return the parent *type constructor* of the data constructor -- (that is, the parent of the data constructor), -- or 'Nothing' if it is a pattern synonym or not in scope. -- That's the parent to use for looking up record fields. find_tycon env con_name | isUnboundName con_name = Just (mkUnboundName (setOccNameSpace tcName (getOccName con_name))) -- If the data con is not in scope, return an unboundName tycon -- That way the calls to lookupRecFieldOcc in rn_fld won't generate -- an error cascade; see Trac #14307 | Just (AConLike (RealDataCon dc)) <- wiredInNameTyThing_maybe con_name = Just (tyConName (dataConTyCon dc)) -- Special case for [], which is built-in syntax -- and not in the GlobalRdrEnv (Trac #8448) | Just gre <- lookupGRE_Name env con_name = case gre_par gre of ParentIs p -> Just p _ -> Nothing -- Can happen if the con_name -- is for a pattern synonym | otherwise = Nothing -- Data constructor not lexically in scope at all -- See Note [Disambiguation and Template Haskell] dup_flds :: [NE.NonEmpty RdrName] -- Each list represents a RdrName that occurred more than once -- (the list contains all occurrences) -- Each list in dup_fields is non-empty (_, dup_flds) = removeDups compare (getFieldLbls flds) {- Note [Disambiguation and Template Haskell] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Consider (Trac #12130) module Foo where import M b = $(funny) module M(funny) where data T = MkT { x :: Int } funny :: Q Exp funny = [| MkT { x = 3 } |] When we splice, neither T nor MkT are lexically in scope, so find_tycon will fail. But there is no need for disambiguation anyway, so we just return Nothing -} rnHsRecUpdFields :: [LHsRecUpdField GhcPs] -> RnM ([LHsRecUpdField GhcRn], FreeVars) rnHsRecUpdFields flds = do { pun_ok <- xoptM LangExt.RecordPuns ; overload_ok <- xoptM LangExt.DuplicateRecordFields ; (flds1, fvss) <- mapAndUnzipM (rn_fld pun_ok overload_ok) flds ; mapM_ (addErr . dupFieldErr HsRecFieldUpd) dup_flds -- Check for an empty record update e {} -- NB: don't complain about e { .. }, because rn_dotdot has done that already ; when (null flds) $ addErr emptyUpdateErr ; return (flds1, plusFVs fvss) } where doc = text "constructor field name" rn_fld :: Bool -> Bool -> LHsRecUpdField GhcPs -> RnM (LHsRecUpdField GhcRn, FreeVars) rn_fld pun_ok overload_ok (L l (HsRecField { hsRecFieldLbl = L loc f , hsRecFieldArg = arg , hsRecPun = pun })) = do { let lbl = rdrNameAmbiguousFieldOcc f ; sel <- setSrcSpan loc $ -- Defer renaming of overloaded fields to the typechecker -- See Note [Disambiguating record fields] in TcExpr if overload_ok then do { mb <- lookupGlobalOccRn_overloaded overload_ok lbl ; case mb of Nothing -> do { addErr (unknownSubordinateErr doc lbl) ; return (Right []) } Just r -> return r } else fmap Left $ lookupGlobalOccRn lbl ; arg' <- if pun then do { checkErr pun_ok (badPun (L loc lbl)) -- Discard any module qualifier (#11662) ; let arg_rdr = mkRdrUnqual (rdrNameOcc lbl) ; return (L loc (HsVar (L loc arg_rdr))) } else return arg ; (arg'', fvs) <- rnLExpr arg' ; let fvs' = case sel of Left sel_name -> fvs `addOneFV` sel_name Right [sel_name] -> fvs `addOneFV` sel_name Right _ -> fvs lbl' = case sel of Left sel_name -> L loc (Unambiguous (L loc lbl) sel_name) Right [sel_name] -> L loc (Unambiguous (L loc lbl) sel_name) Right _ -> L loc (Ambiguous (L loc lbl) PlaceHolder) ; return (L l (HsRecField { hsRecFieldLbl = lbl' , hsRecFieldArg = arg'' , hsRecPun = pun }), fvs') } dup_flds :: [NE.NonEmpty RdrName] -- Each list represents a RdrName that occurred more than once -- (the list contains all occurrences) -- Each list in dup_fields is non-empty (_, dup_flds) = removeDups compare (getFieldUpdLbls flds) getFieldIds :: [LHsRecField GhcRn arg] -> [Name] getFieldIds flds = map (unLoc . hsRecFieldSel . unLoc) flds getFieldLbls :: [LHsRecField id arg] -> [RdrName] getFieldLbls flds = map (unLoc . rdrNameFieldOcc . unLoc . hsRecFieldLbl . unLoc) flds getFieldUpdLbls :: [LHsRecUpdField id] -> [RdrName] getFieldUpdLbls flds = map (rdrNameAmbiguousFieldOcc . unLoc . hsRecFieldLbl . unLoc) flds needFlagDotDot :: HsRecFieldContext -> SDoc needFlagDotDot ctxt = vcat [text "Illegal `..' in record" <+> pprRFC ctxt, text "Use RecordWildCards to permit this"] badDotDotCon :: Name -> SDoc badDotDotCon con = vcat [ text "Illegal `..' notation for constructor" <+> quotes (ppr con) , nest 2 (text "The constructor has no labelled fields") ] emptyUpdateErr :: SDoc emptyUpdateErr = text "Empty record update" badPun :: Located RdrName -> SDoc badPun fld = vcat [text "Illegal use of punning for field" <+> quotes (ppr fld), text "Use NamedFieldPuns to permit this"] dupFieldErr :: HsRecFieldContext -> NE.NonEmpty RdrName -> SDoc dupFieldErr ctxt dups = hsep [text "duplicate field name", quotes (ppr (NE.head dups)), text "in record", pprRFC ctxt] pprRFC :: HsRecFieldContext -> SDoc pprRFC (HsRecFieldCon {}) = text "construction" pprRFC (HsRecFieldPat {}) = text "pattern" pprRFC (HsRecFieldUpd {}) = text "update" {- ************************************************************************ * * \subsubsection{Literals} * * ************************************************************************ When literals occur we have to make sure that the types and classes they involve are made available. -} rnLit :: HsLit p -> RnM () rnLit (HsChar _ c) = checkErr (inCharRange c) (bogusCharError c) rnLit _ = return () -- Turn a Fractional-looking literal which happens to be an integer into an -- Integer-looking literal. generalizeOverLitVal :: OverLitVal -> OverLitVal generalizeOverLitVal (HsFractional (FL {fl_text=src,fl_neg=neg,fl_value=val})) | denominator val == 1 = HsIntegral (IL {il_text=src,il_neg=neg,il_value=numerator val}) generalizeOverLitVal lit = lit isNegativeZeroOverLit :: HsOverLit t -> Bool isNegativeZeroOverLit lit = case ol_val lit of HsIntegral i -> 0 == il_value i && il_neg i HsFractional f -> 0 == fl_value f && fl_neg f _ -> False {- Note [Negative zero] ~~~~~~~~~~~~~~~~~~~~~~~~~ There were problems with negative zero in conjunction with Negative Literals extension. Numeric literal value is contained in Integer and Rational types inside IntegralLit and FractionalLit. These types cannot represent negative zero value. So we had to add explicit field 'neg' which would hold information about literal sign. Here in rnOverLit we use it to detect negative zeroes and in this case return not only literal itself but also negateName so that users can apply it explicitly. In this case it stays negative zero. Trac #13211 -} rnOverLit :: HsOverLit t -> RnM ((HsOverLit GhcRn, Maybe (HsExpr GhcRn)), FreeVars) rnOverLit origLit = do { opt_NumDecimals <- xoptM LangExt.NumDecimals ; let { lit@(OverLit {ol_val=val}) | opt_NumDecimals = origLit {ol_val = generalizeOverLitVal (ol_val origLit)} | otherwise = origLit } ; let std_name = hsOverLitName val ; (SyntaxExpr { syn_expr = from_thing_name }, fvs1) <- lookupSyntaxName std_name ; let rebindable = case from_thing_name of HsVar (L _ v) -> v /= std_name _ -> panic "rnOverLit" ; let lit' = lit { ol_witness = from_thing_name , ol_rebindable = rebindable , ol_type = placeHolderType } ; if isNegativeZeroOverLit lit' then do { (SyntaxExpr { syn_expr = negate_name }, fvs2) <- lookupSyntaxName negateName ; return ((lit' { ol_val = negateOverLitVal val }, Just negate_name) , fvs1 `plusFV` fvs2) } else return ((lit', Nothing), fvs1) } {- ************************************************************************ * * \subsubsection{Errors} * * ************************************************************************ -} patSigErr :: Outputable a => a -> SDoc patSigErr ty = (text "Illegal signature in pattern:" <+> ppr ty) $$ nest 4 (text "Use ScopedTypeVariables to permit it") bogusCharError :: Char -> SDoc bogusCharError c = text "character literal out of range: '\\" <> char c <> char '\'' badViewPat :: Pat GhcPs -> SDoc badViewPat pat = vcat [text "Illegal view pattern: " <+> ppr pat, text "Use ViewPatterns to enable view patterns"]