{-# LANGUAGE NamedFieldPuns #-} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE RankNTypes #-} {-# LANGUAGE OverloadedStrings #-} {-# LANGUAGE TypeFamilies #-} module TcRnExports (tcRnExports, exports_from_avail) where import GhcPrelude import HsSyn import PrelNames import RdrName import TcRnMonad import TcEnv import TcType import RnNames import RnEnv import RnUnbound ( reportUnboundName ) import ErrUtils import Id import IdInfo import Module import Name import NameEnv import NameSet import Avail import TyCon import SrcLoc import HscTypes import Outputable import ConLike import DataCon import PatSyn import Maybes import Util (capitalise) import Control.Monad import DynFlags import RnHsDoc ( rnHsDoc ) import RdrHsSyn ( setRdrNameSpace ) import Data.Either ( partitionEithers ) {- ************************************************************************ * * \subsection{Export list processing} * * ************************************************************************ Processing the export list. You might think that we should record things that appear in the export list as ``occurrences'' (using @addOccurrenceName@), but you'd be wrong. We do check (here) that they are in scope, but there is no need to slurp in their actual declaration (which is what @addOccurrenceName@ forces). Indeed, doing so would big trouble when compiling @PrelBase@, because it re-exports @GHC@, which includes @takeMVar#@, whose type includes @ConcBase.StateAndSynchVar#@, and so on... Note [Exports of data families] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Suppose you see (Trac #5306) module M where import X( F ) data instance F Int = FInt What does M export? AvailTC F [FInt] or AvailTC F [F,FInt]? The former is strictly right because F isn't defined in this module. But then you can never do an explicit import of M, thus import M( F( FInt ) ) because F isn't exported by M. Nor can you import FInt alone from here import M( FInt ) because we don't have syntax to support that. (It looks like an import of the type FInt.) At one point I implemented a compromise: * When constructing exports with no export list, or with module M( module M ), we add the parent to the exports as well. * But not when you see module M( f ), even if f is a class method with a parent. * Nor when you see module M( module N ), with N /= M. But the compromise seemed too much of a hack, so we backed it out. You just have to use an explicit export list: module M( F(..) ) where ... -} data ExportAccum -- The type of the accumulating parameter of -- the main worker function in rnExports = ExportAccum [(LIE GhcRn, Avails)] -- Export items with names and -- their exported stuff -- Not nub'd! ExportOccMap -- Tracks exported occurrence names emptyExportAccum :: ExportAccum emptyExportAccum = ExportAccum [] emptyOccEnv type ExportOccMap = OccEnv (Name, IE GhcPs) -- Tracks what a particular exported OccName -- in an export list refers to, and which item -- it came from. It's illegal to export two distinct things -- that have the same occurrence name tcRnExports :: Bool -- False => no 'module M(..) where' header at all -> Maybe (Located [LIE GhcPs]) -- Nothing => no explicit export list -> TcGblEnv -> RnM TcGblEnv -- Complains if two distinct exports have same OccName -- Warns about identical exports. -- Complains about exports items not in scope tcRnExports explicit_mod exports tcg_env@TcGblEnv { tcg_mod = this_mod, tcg_rdr_env = rdr_env, tcg_imports = imports, tcg_src = hsc_src } = unsetWOptM Opt_WarnWarningsDeprecations $ -- Do not report deprecations arising from the export -- list, to avoid bleating about re-exporting a deprecated -- thing (especially via 'module Foo' export item) do { -- If the module header is omitted altogether, then behave -- as if the user had written "module Main(main) where..." -- EXCEPT in interactive mode, when we behave as if he had -- written "module Main where ..." -- Reason: don't want to complain about 'main' not in scope -- in interactive mode ; dflags <- getDynFlags ; let real_exports | explicit_mod = exports | ghcLink dflags == LinkInMemory = Nothing | otherwise = Just (noLoc [noLoc (IEVar (noLoc (IEName $ noLoc main_RDR_Unqual)))]) -- ToDo: the 'noLoc' here is unhelpful if 'main' -- turns out to be out of scope ; let do_it = exports_from_avail real_exports rdr_env imports this_mod ; (rn_exports, final_avails) <- if hsc_src == HsigFile then do (msgs, mb_r) <- tryTc do_it case mb_r of Just r -> return r Nothing -> addMessages msgs >> failM else checkNoErrs do_it ; let final_ns = availsToNameSetWithSelectors final_avails ; traceRn "rnExports: Exports:" (ppr final_avails) ; let new_tcg_env = tcg_env { tcg_exports = final_avails, tcg_rn_exports = case tcg_rn_exports tcg_env of Nothing -> Nothing Just _ -> rn_exports, tcg_dus = tcg_dus tcg_env `plusDU` usesOnly final_ns } ; failIfErrsM ; return new_tcg_env } exports_from_avail :: Maybe (Located [LIE GhcPs]) -- Nothing => no explicit export list -> GlobalRdrEnv -> ImportAvails -- Imported modules; this is used to test if a -- 'module Foo' export is valid (it's not valid -- if we didn't import Foo!) -> Module -> RnM (Maybe [(LIE GhcRn, Avails)], Avails) -- (Nothing, _) <=> no explicit export list -- if explicit export list is present it contains -- each renamed export item together with its exported -- names. exports_from_avail Nothing rdr_env _imports _this_mod -- The same as (module M) where M is the current module name, -- so that's how we handle it, except we also export the data family -- when a data instance is exported. = do { ; warnMissingExportList <- woptM Opt_WarnMissingExportList ; warnIfFlag Opt_WarnMissingExportList warnMissingExportList (missingModuleExportWarn $ moduleName _this_mod) ; let avails = map fix_faminst . gresToAvailInfo . filter isLocalGRE . globalRdrEnvElts $ rdr_env ; return (Nothing, avails) } where -- #11164: when we define a data instance -- but not data family, re-export the family -- Even though we don't check whether this is actually a data family -- only data families can locally define subordinate things (`ns` here) -- without locally defining (and instead importing) the parent (`n`) fix_faminst (AvailTC n ns flds) = let new_ns = case ns of [] -> [n] (p:_) -> if p == n then ns else n:ns in AvailTC n new_ns flds fix_faminst avail = avail exports_from_avail (Just (L _ rdr_items)) rdr_env imports this_mod = do ExportAccum ie_avails _ <- foldAndRecoverM do_litem emptyExportAccum rdr_items let final_exports = nubAvails (concat (map snd ie_avails)) -- Combine families return (Just ie_avails, final_exports) where do_litem :: ExportAccum -> LIE GhcPs -> RnM ExportAccum do_litem acc lie = setSrcSpan (getLoc lie) (exports_from_item acc lie) -- Maps a parent to its in-scope children kids_env :: NameEnv [GlobalRdrElt] kids_env = mkChildEnv (globalRdrEnvElts rdr_env) imported_modules = [ imv_name imv | xs <- moduleEnvElts $ imp_mods imports , imv <- importedByUser xs ] exports_from_item :: ExportAccum -> LIE GhcPs -> RnM ExportAccum exports_from_item acc@(ExportAccum ie_avails occs) (L loc (IEModuleContents (L lm mod))) | let earlier_mods = [ mod | ((L _ (IEModuleContents (L _ mod))), _) <- ie_avails ] , mod `elem` earlier_mods -- Duplicate export of M = do { warnIfFlag Opt_WarnDuplicateExports True (dupModuleExport mod) ; return acc } | otherwise = do { let { exportValid = (mod `elem` imported_modules) || (moduleName this_mod == mod) ; gre_prs = pickGREsModExp mod (globalRdrEnvElts rdr_env) ; new_exports = map (availFromGRE . fst) gre_prs ; names = map (gre_name . fst) gre_prs ; all_gres = foldr (\(gre1,gre2) gres -> gre1 : gre2 : gres) [] gre_prs } ; checkErr exportValid (moduleNotImported mod) ; warnIfFlag Opt_WarnDodgyExports (exportValid && null gre_prs) (nullModuleExport mod) ; traceRn "efa" (ppr mod $$ ppr all_gres) ; addUsedGREs all_gres ; occs' <- check_occs (IEModuleContents (noLoc mod)) occs names -- This check_occs not only finds conflicts -- between this item and others, but also -- internally within this item. That is, if -- 'M.x' is in scope in several ways, we'll have -- several members of mod_avails with the same -- OccName. ; traceRn "export_mod" (vcat [ ppr mod , ppr new_exports ]) ; return (ExportAccum (((L loc (IEModuleContents (L lm mod))), new_exports) : ie_avails) occs') } exports_from_item acc@(ExportAccum lie_avails occs) (L loc ie) | isDoc ie = do new_ie <- lookup_doc_ie ie return (ExportAccum ((L loc new_ie, []) : lie_avails) occs) | otherwise = do (new_ie, avail) <- setSrcSpan loc $ lookup_ie ie if isUnboundName (ieName new_ie) then return acc -- Avoid error cascade else do occs' <- check_occs ie occs (availNames avail) return (ExportAccum ((L loc new_ie, [avail]) : lie_avails) occs') ------------- lookup_ie :: IE GhcPs -> RnM (IE GhcRn, AvailInfo) lookup_ie (IEVar (L l rdr)) = do (name, avail) <- lookupGreAvailRn $ ieWrappedName rdr return (IEVar (L l (replaceWrappedName rdr name)), avail) lookup_ie (IEThingAbs (L l rdr)) = do (name, avail) <- lookupGreAvailRn $ ieWrappedName rdr return (IEThingAbs (L l (replaceWrappedName rdr name)), avail) lookup_ie ie@(IEThingAll n') = do (n, avail, flds) <- lookup_ie_all ie n' let name = unLoc n return (IEThingAll (replaceLWrappedName n' (unLoc n)) , AvailTC name (name:avail) flds) lookup_ie ie@(IEThingWith l wc sub_rdrs _) = do (lname, subs, avails, flds) <- addExportErrCtxt ie $ lookup_ie_with l sub_rdrs (_, all_avail, all_flds) <- case wc of NoIEWildcard -> return (lname, [], []) IEWildcard _ -> lookup_ie_all ie l let name = unLoc lname return (IEThingWith (replaceLWrappedName l name) wc subs (flds ++ (map noLoc all_flds)), AvailTC name (name : avails ++ all_avail) (map unLoc flds ++ all_flds)) lookup_ie _ = panic "lookup_ie" -- Other cases covered earlier lookup_ie_with :: LIEWrappedName RdrName -> [LIEWrappedName RdrName] -> RnM (Located Name, [LIEWrappedName Name], [Name], [Located FieldLabel]) lookup_ie_with (L l rdr) sub_rdrs = do name <- lookupGlobalOccRn $ ieWrappedName rdr (non_flds, flds) <- lookupChildrenExport name sub_rdrs if isUnboundName name then return (L l name, [], [name], []) else return (L l name, non_flds , map (ieWrappedName . unLoc) non_flds , flds) lookup_ie_all :: IE GhcPs -> LIEWrappedName RdrName -> RnM (Located Name, [Name], [FieldLabel]) lookup_ie_all ie (L l rdr) = do name <- lookupGlobalOccRn $ ieWrappedName rdr let gres = findChildren kids_env name (non_flds, flds) = classifyGREs gres addUsedKids (ieWrappedName rdr) gres warnDodgyExports <- woptM Opt_WarnDodgyExports when (null gres) $ if isTyConName name then when warnDodgyExports $ addWarn (Reason Opt_WarnDodgyExports) (dodgyExportWarn name) else -- This occurs when you export T(..), but -- only import T abstractly, or T is a synonym. addErr (exportItemErr ie) return (L l name, non_flds, flds) ------------- lookup_doc_ie :: IE GhcPs -> RnM (IE GhcRn) lookup_doc_ie (IEGroup lev doc) = do rn_doc <- rnHsDoc doc return (IEGroup lev rn_doc) lookup_doc_ie (IEDoc doc) = do rn_doc <- rnHsDoc doc return (IEDoc rn_doc) lookup_doc_ie (IEDocNamed str) = return (IEDocNamed str) lookup_doc_ie _ = panic "lookup_doc_ie" -- Other cases covered earlier -- In an export item M.T(A,B,C), we want to treat the uses of -- A,B,C as if they were M.A, M.B, M.C -- Happily pickGREs does just the right thing addUsedKids :: RdrName -> [GlobalRdrElt] -> RnM () addUsedKids parent_rdr kid_gres = addUsedGREs (pickGREs parent_rdr kid_gres) classifyGREs :: [GlobalRdrElt] -> ([Name], [FieldLabel]) classifyGREs = partitionEithers . map classifyGRE classifyGRE :: GlobalRdrElt -> Either Name FieldLabel classifyGRE gre = case gre_par gre of FldParent _ Nothing -> Right (FieldLabel (occNameFS (nameOccName n)) False n) FldParent _ (Just lbl) -> Right (FieldLabel lbl True n) _ -> Left n where n = gre_name gre isDoc :: IE GhcPs -> Bool isDoc (IEDoc _) = True isDoc (IEDocNamed _) = True isDoc (IEGroup _ _) = True isDoc _ = False -- Renaming and typechecking of exports happens after everything else has -- been typechecked. -- Renaming exports lists is a minefield. Five different things can appear in -- children export lists ( T(A, B, C) ). -- 1. Record selectors -- 2. Type constructors -- 3. Data constructors -- 4. Pattern Synonyms -- 5. Pattern Synonym Selectors -- -- However, things get put into weird name spaces. -- 1. Some type constructors are parsed as variables (-.->) for example. -- 2. All data constructors are parsed as type constructors -- 3. When there is ambiguity, we default type constructors to data -- constructors and require the explicit `type` keyword for type -- constructors. -- -- This function first establishes the possible namespaces that an -- identifier might be in (`choosePossibleNameSpaces`). -- -- Then for each namespace in turn, tries to find the correct identifier -- there returning the first positive result or the first terminating -- error. -- lookupChildrenExport :: Name -> [LIEWrappedName RdrName] -> RnM ([LIEWrappedName Name], [Located FieldLabel]) lookupChildrenExport spec_parent rdr_items = do xs <- mapAndReportM doOne rdr_items return $ partitionEithers xs where -- Pick out the possible namespaces in order of priority -- This is a consequence of how the parser parses all -- data constructors as type constructors. choosePossibleNamespaces :: NameSpace -> [NameSpace] choosePossibleNamespaces ns | ns == varName = [varName, tcName] | ns == tcName = [dataName, tcName] | otherwise = [ns] -- Process an individual child doOne :: LIEWrappedName RdrName -> RnM (Either (LIEWrappedName Name) (Located FieldLabel)) doOne n = do let bareName = (ieWrappedName . unLoc) n lkup v = lookupSubBndrOcc_helper False True spec_parent (setRdrNameSpace bareName v) name <- combineChildLookupResult $ map lkup $ choosePossibleNamespaces (rdrNameSpace bareName) traceRn "lookupChildrenExport" (ppr name) -- Default to data constructors for slightly better error -- messages let unboundName :: RdrName unboundName = if rdrNameSpace bareName == varName then bareName else setRdrNameSpace bareName dataName case name of NameNotFound -> do { ub <- reportUnboundName unboundName ; let l = getLoc n ; return (Left (L l (IEName (L l ub))))} FoundFL fls -> return $ Right (L (getLoc n) fls) FoundName par name -> do { checkPatSynParent spec_parent par name ; return $ Left (replaceLWrappedName n name) } IncorrectParent p g td gs -> failWithDcErr p g td gs -- Note: [Typing Pattern Synonym Exports] -- It proved quite a challenge to precisely specify which pattern synonyms -- should be allowed to be bundled with which type constructors. -- In the end it was decided to be quite liberal in what we allow. Below is -- how Simon described the implementation. -- -- "Personally I think we should Keep It Simple. All this talk of -- satisfiability makes me shiver. I suggest this: allow T( P ) in all -- situations except where `P`'s type is ''visibly incompatible'' with -- `T`. -- -- What does "visibly incompatible" mean? `P` is visibly incompatible -- with -- `T` if -- * `P`'s type is of form `... -> S t1 t2` -- * `S` is a data/newtype constructor distinct from `T` -- -- Nothing harmful happens if we allow `P` to be exported with -- a type it can't possibly be useful for, but specifying a tighter -- relationship is very awkward as you have discovered." -- -- Note that this allows *any* pattern synonym to be bundled with any -- datatype type constructor. For example, the following pattern `P` can be -- bundled with any type. -- -- ``` -- pattern P :: (A ~ f) => f -- ``` -- -- So we provide basic type checking in order to help the user out, most -- pattern synonyms are defined with definite type constructors, but don't -- actually prevent a library author completely confusing their users if -- they want to. -- -- So, we check for exactly four things -- 1. The name arises from a pattern synonym definition. (Either a pattern -- synonym constructor or a pattern synonym selector) -- 2. The pattern synonym is only bundled with a datatype or newtype. -- 3. Check that the head of the result type constructor is an actual type -- constructor and not a type variable. (See above example) -- 4. Is so, check that this type constructor is the same as the parent -- type constructor. -- -- -- Note: [Types of TyCon] -- -- This check appears to be overlly complicated, Richard asked why it -- is not simply just `isAlgTyCon`. The answer for this is that -- a classTyCon is also an `AlgTyCon` which we explicitly want to disallow. -- (It is either a newtype or data depending on the number of methods) -- -- | Given a resolved name in the children export list and a parent. Decide -- whether we are allowed to export the child with the parent. -- Invariant: gre_par == NoParent -- See note [Typing Pattern Synonym Exports] checkPatSynParent :: Name -- ^ Alleged parent type constructor -- User wrote T( P, Q ) -> Parent -- The parent of P we discovered -> Name -- ^ Either a -- a) Pattern Synonym Constructor -- b) A pattern synonym selector -> TcM () -- Fails if wrong parent checkPatSynParent _ (ParentIs {}) _ = return () checkPatSynParent _ (FldParent {}) _ = return () checkPatSynParent parent NoParent mpat_syn | isUnboundName parent -- Avoid an error cascade = return () | otherwise = do { parent_ty_con <- tcLookupTyCon parent ; mpat_syn_thing <- tcLookupGlobal mpat_syn -- 1. Check that the Id was actually from a thing associated with patsyns ; case mpat_syn_thing of AnId i | isId i , RecSelId { sel_tycon = RecSelPatSyn p } <- idDetails i -> handle_pat_syn (selErr i) parent_ty_con p AConLike (PatSynCon p) -> handle_pat_syn (psErr p) parent_ty_con p _ -> failWithDcErr parent mpat_syn (ppr mpat_syn) [] } where psErr = exportErrCtxt "pattern synonym" selErr = exportErrCtxt "pattern synonym record selector" assocClassErr :: SDoc assocClassErr = text "Pattern synonyms can be bundled only with datatypes." handle_pat_syn :: SDoc -> TyCon -- ^ Parent TyCon -> PatSyn -- ^ Corresponding bundled PatSyn -- and pretty printed origin -> TcM () handle_pat_syn doc ty_con pat_syn -- 2. See note [Types of TyCon] | not $ isTyConWithSrcDataCons ty_con = addErrCtxt doc $ failWithTc assocClassErr -- 3. Is the head a type variable? | Nothing <- mtycon = return () -- 4. Ok. Check they are actually the same type constructor. | Just p_ty_con <- mtycon, p_ty_con /= ty_con = addErrCtxt doc $ failWithTc typeMismatchError -- 5. We passed! | otherwise = return () where expected_res_ty = mkTyConApp ty_con (mkTyVarTys (tyConTyVars ty_con)) (_, _, _, _, _, res_ty) = patSynSig pat_syn mtycon = fst <$> tcSplitTyConApp_maybe res_ty typeMismatchError :: SDoc typeMismatchError = text "Pattern synonyms can only be bundled with matching type constructors" $$ text "Couldn't match expected type of" <+> quotes (ppr expected_res_ty) <+> text "with actual type of" <+> quotes (ppr res_ty) {-===========================================================================-} check_occs :: IE GhcPs -> ExportOccMap -> [Name] -> RnM ExportOccMap check_occs ie occs names -- 'names' are the entities specifed by 'ie' = foldlM check occs names where check occs name = case lookupOccEnv occs name_occ of Nothing -> return (extendOccEnv occs name_occ (name, ie)) Just (name', ie') | name == name' -- Duplicate export -- But we don't want to warn if the same thing is exported -- by two different module exports. See ticket #4478. -> do { warnIfFlag Opt_WarnDuplicateExports (not (dupExport_ok name ie ie')) (dupExportWarn name_occ ie ie') ; return occs } | otherwise -- Same occ name but different names: an error -> do { global_env <- getGlobalRdrEnv ; addErr (exportClashErr global_env name' name ie' ie) ; return occs } where name_occ = nameOccName name dupExport_ok :: Name -> IE GhcPs -> IE GhcPs -> Bool -- The Name is exported by both IEs. Is that ok? -- "No" iff the name is mentioned explicitly in both IEs -- or one of the IEs mentions the name *alone* -- "Yes" otherwise -- -- Examples of "no": module M( f, f ) -- module M( fmap, Functor(..) ) -- module M( module Data.List, head ) -- -- Example of "yes" -- module M( module A, module B ) where -- import A( f ) -- import B( f ) -- -- Example of "yes" (Trac #2436) -- module M( C(..), T(..) ) where -- class C a where { data T a } -- instance C Int where { data T Int = TInt } -- -- Example of "yes" (Trac #2436) -- module Foo ( T ) where -- data family T a -- module Bar ( T(..), module Foo ) where -- import Foo -- data instance T Int = TInt dupExport_ok n ie1 ie2 = not ( single ie1 || single ie2 || (explicit_in ie1 && explicit_in ie2) ) where explicit_in (IEModuleContents _) = False -- module M explicit_in (IEThingAll r) = nameOccName n == rdrNameOcc (ieWrappedName $ unLoc r) -- T(..) explicit_in _ = True single IEVar {} = True single IEThingAbs {} = True single _ = False dupModuleExport :: ModuleName -> SDoc dupModuleExport mod = hsep [text "Duplicate", quotes (text "Module" <+> ppr mod), text "in export list"] moduleNotImported :: ModuleName -> SDoc moduleNotImported mod = hsep [text "The export item", quotes (text "module" <+> ppr mod), text "is not imported"] nullModuleExport :: ModuleName -> SDoc nullModuleExport mod = hsep [text "The export item", quotes (text "module" <+> ppr mod), text "exports nothing"] missingModuleExportWarn :: ModuleName -> SDoc missingModuleExportWarn mod = hsep [text "The export item", quotes (text "module" <+> ppr mod), text "is missing an export list"] dodgyExportWarn :: Name -> SDoc dodgyExportWarn item = dodgyMsg (text "export") item (dodgyMsgInsert item :: IE GhcRn) exportErrCtxt :: Outputable o => String -> o -> SDoc exportErrCtxt herald exp = text "In the" <+> text (herald ++ ":") <+> ppr exp addExportErrCtxt :: (OutputableBndrId s) => IE s -> TcM a -> TcM a addExportErrCtxt ie = addErrCtxt exportCtxt where exportCtxt = text "In the export:" <+> ppr ie exportItemErr :: IE GhcPs -> SDoc exportItemErr export_item = sep [ text "The export item" <+> quotes (ppr export_item), text "attempts to export constructors or class methods that are not visible here" ] dupExportWarn :: OccName -> IE GhcPs -> IE GhcPs -> SDoc dupExportWarn occ_name ie1 ie2 = hsep [quotes (ppr occ_name), text "is exported by", quotes (ppr ie1), text "and", quotes (ppr ie2)] dcErrMsg :: Name -> String -> SDoc -> [SDoc] -> SDoc dcErrMsg ty_con what_is thing parents = text "The type constructor" <+> quotes (ppr ty_con) <+> text "is not the parent of the" <+> text what_is <+> quotes thing <> char '.' $$ text (capitalise what_is) <> text "s can only be exported with their parent type constructor." $$ (case parents of [] -> empty [_] -> text "Parent:" _ -> text "Parents:") <+> fsep (punctuate comma parents) failWithDcErr :: Name -> Name -> SDoc -> [Name] -> TcM a failWithDcErr parent thing thing_doc parents = do ty_thing <- tcLookupGlobal thing failWithTc $ dcErrMsg parent (tyThingCategory' ty_thing) thing_doc (map ppr parents) where tyThingCategory' :: TyThing -> String tyThingCategory' (AnId i) | isRecordSelector i = "record selector" tyThingCategory' i = tyThingCategory i exportClashErr :: GlobalRdrEnv -> Name -> Name -> IE GhcPs -> IE GhcPs -> MsgDoc exportClashErr global_env name1 name2 ie1 ie2 = vcat [ text "Conflicting exports for" <+> quotes (ppr occ) <> colon , ppr_export ie1' name1' , ppr_export ie2' name2' ] where occ = nameOccName name1 ppr_export ie name = nest 3 (hang (quotes (ppr ie) <+> text "exports" <+> quotes (ppr name)) 2 (pprNameProvenance (get_gre name))) -- get_gre finds a GRE for the Name, so that we can show its provenance get_gre name = fromMaybe (pprPanic "exportClashErr" (ppr name)) (lookupGRE_Name global_env name) get_loc name = greSrcSpan (get_gre name) (name1', ie1', name2', ie2') = if get_loc name1 < get_loc name2 then (name1, ie1, name2, ie2) else (name2, ie2, name1, ie1)