2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[RnNames]{Extracting imported and top-level names in scope}
8 rnImports, importsFromLocalDecls,
10 getLocalDeclBinders, extendRdrEnvRn,
11 reportUnusedNames, reportDeprecations
14 #include "HsVersions.h"
16 import DynFlags ( DynFlag(..), GhcMode(..), DynFlags(..) )
17 import HsSyn ( IE(..), ieName, ImportDecl(..), LImportDecl,
18 ForeignDecl(..), HsGroup(..), HsValBinds(..),
19 Sig(..), collectHsBindLocatedBinders, tyClDeclNames,
20 instDeclATs, isIdxTyDecl,
23 import RnHsDoc ( rnHsDoc )
24 import IfaceEnv ( ifaceExportNames )
25 import LoadIface ( loadSrcInterface )
26 import TcRnMonad hiding (LIE)
33 import OccName ( srcDataName, pprNonVarNameSpace,
35 OccEnv, mkOccEnv, lookupOccEnv, emptyOccEnv,
37 import HscTypes ( GenAvailInfo(..), AvailInfo, availNames, availName,
38 HomePackageTable, PackageIfaceTable,
39 mkPrintUnqualified, availsToNameSet,
40 Deprecs(..), ModIface(..), Dependencies(..),
41 lookupIfaceByModule, ExternalPackageState(..)
43 import RdrName ( RdrName, rdrNameOcc, setRdrNameSpace, Parent(..),
44 GlobalRdrEnv, mkGlobalRdrEnv, GlobalRdrElt(..),
45 emptyGlobalRdrEnv, plusGlobalRdrEnv, globalRdrEnvElts,
46 extendGlobalRdrEnv, lookupGlobalRdrEnv, lookupGRE_Name,
47 Provenance(..), ImportSpec(..), ImpDeclSpec(..), ImpItemSpec(..),
48 importSpecLoc, importSpecModule, isLocalGRE, pprNameProvenance,
49 unQualSpecOK, qualSpecOK )
52 import SrcLoc ( Located(..), mkGeneralSrcSpan, getLoc,
53 unLoc, noLoc, srcLocSpan, SrcSpan )
56 import BasicTypes ( DeprecTxt )
57 import DriverPhases ( isHsBoot )
60 import Data.List ( partition, concatMap )
61 import IO ( openFile, IOMode(..) )
67 %************************************************************************
71 %************************************************************************
74 rnImports :: [LImportDecl RdrName]
75 -> RnM ([LImportDecl Name], GlobalRdrEnv, ImportAvails)
78 -- PROCESS IMPORT DECLS
79 -- Do the non {- SOURCE -} ones first, so that we get a helpful
80 -- warning for {- SOURCE -} ones that are unnecessary
81 = do this_mod <- getModule
82 implicit_prelude <- doptM Opt_ImplicitPrelude
83 let all_imports = mk_prel_imports this_mod implicit_prelude ++ imports
84 (source, ordinary) = partition is_source_import all_imports
85 is_source_import (L _ (ImportDecl _ is_boot _ _ _)) = is_boot
87 stuff1 <- mapM (rnImportDecl this_mod) ordinary
88 stuff2 <- mapM (rnImportDecl this_mod) source
89 let (decls, rdr_env, imp_avails) = combine (stuff1 ++ stuff2)
90 return (decls, rdr_env, imp_avails)
93 -- NB: opt_NoImplicitPrelude is slightly different to import Prelude ();
94 -- because the former doesn't even look at Prelude.hi for instance
95 -- declarations, whereas the latter does.
96 mk_prel_imports this_mod implicit_prelude
98 || explicit_prelude_import
99 || not implicit_prelude
101 | otherwise = [preludeImportDecl]
102 explicit_prelude_import
103 = notNull [ () | L _ (ImportDecl mod _ _ _ _) <- imports,
104 unLoc mod == pRELUDE_NAME ]
106 combine :: [(LImportDecl Name, GlobalRdrEnv, ImportAvails)]
107 -> ([LImportDecl Name], GlobalRdrEnv, ImportAvails)
108 combine = foldr plus ([], emptyGlobalRdrEnv, emptyImportAvails)
109 where plus (decl, gbl_env1, imp_avails1)
110 (decls, gbl_env2, imp_avails2)
112 gbl_env1 `plusGlobalRdrEnv` gbl_env2,
113 imp_avails1 `plusImportAvails` imp_avails2)
115 preludeImportDecl :: LImportDecl RdrName
118 ImportDecl (L loc pRELUDE_NAME)
119 False {- Not a boot interface -}
120 False {- Not qualified -}
121 Nothing {- No "as" -}
122 Nothing {- No import list -}
124 loc = mkGeneralSrcSpan FSLIT("Implicit import declaration")
128 rnImportDecl :: Module
129 -> LImportDecl RdrName
130 -> RnM (LImportDecl Name, GlobalRdrEnv, ImportAvails)
132 rnImportDecl this_mod (L loc (ImportDecl loc_imp_mod_name want_boot
133 qual_only as_mod imp_details))
137 -- If there's an error in loadInterface, (e.g. interface
138 -- file not found) we get lots of spurious errors from 'filterImports'
140 imp_mod_name = unLoc loc_imp_mod_name
141 doc = ppr imp_mod_name <+> ptext SLIT("is directly imported")
143 iface <- loadSrcInterface doc imp_mod_name want_boot
145 -- Compiler sanity check: if the import didn't say
146 -- {-# SOURCE #-} we should not get a hi-boot file
147 WARN( not want_boot && mi_boot iface, ppr imp_mod_name ) (do
149 -- Issue a user warning for a redundant {- SOURCE -} import
150 -- NB that we arrange to read all the ordinary imports before
151 -- any of the {- SOURCE -} imports
152 warnIf (want_boot && not (mi_boot iface))
153 (warnRedundantSourceImport imp_mod_name)
156 imp_mod = mi_module iface
157 deprecs = mi_deprecs iface
158 is_orph = mi_orphan iface
159 has_finsts = mi_finsts iface
162 filtered_exports = filter not_this_mod (mi_exports iface)
163 not_this_mod (mod,_) = mod /= this_mod
164 -- If the module exports anything defined in this module, just
165 -- ignore it. Reason: otherwise it looks as if there are two
166 -- local definition sites for the thing, and an error gets
167 -- reported. Easiest thing is just to filter them out up
168 -- front. This situation only arises if a module imports
169 -- itself, or another module that imported it. (Necessarily,
170 -- this invoves a loop.)
172 -- Tiresome consequence: if you say
177 -- module B( AType ) where
178 -- import {-# SOURCE #-} A( AType )
180 -- then you'll get a 'B does not export AType' message. Oh well.
182 qual_mod_name = case as_mod of
183 Nothing -> imp_mod_name
184 Just another_name -> another_name
185 imp_spec = ImpDeclSpec { is_mod = imp_mod_name, is_qual = qual_only,
186 is_dloc = loc, is_as = qual_mod_name }
189 -- Get the total exports from this module
190 total_avails <- ifaceExportNames filtered_exports
192 -- filter the imports according to the import declaration
193 (new_imp_details, gbl_env) <-
194 filterImports iface imp_spec imp_details total_avails
199 -- Compute new transitive dependencies
201 orphans | is_orph = ASSERT( not (imp_mod `elem` dep_orphs deps) )
202 imp_mod : dep_orphs deps
203 | otherwise = dep_orphs deps
205 finsts | has_finsts = ASSERT( not (imp_mod `elem` dep_finsts deps) )
206 imp_mod : dep_finsts deps
207 | otherwise = dep_finsts deps
209 pkg = modulePackageId (mi_module iface)
211 (dependent_mods, dependent_pkgs)
212 | pkg == thisPackage dflags =
213 -- Imported module is from the home package
214 -- Take its dependent modules and add imp_mod itself
215 -- Take its dependent packages unchanged
217 -- NB: (dep_mods deps) might include a hi-boot file
218 -- for the module being compiled, CM. Do *not* filter
219 -- this out (as we used to), because when we've
220 -- finished dealing with the direct imports we want to
221 -- know if any of them depended on CM.hi-boot, in
222 -- which case we should do the hi-boot consistency
223 -- check. See LoadIface.loadHiBootInterface
224 ((imp_mod_name, want_boot) : dep_mods deps, dep_pkgs deps)
227 -- Imported module is from another package
228 -- Dump the dependent modules
229 -- Add the package imp_mod comes from to the dependent packages
230 ASSERT2( not (pkg `elem` dep_pkgs deps), ppr pkg <+> ppr (dep_pkgs deps) )
231 ([], pkg : dep_pkgs deps)
233 -- True <=> import M ()
234 import_all = case imp_details of
235 Just (is_hiding, ls) -> not is_hiding && null ls
238 imports = ImportAvails {
239 imp_mods = unitModuleEnv imp_mod (imp_mod, import_all, loc),
242 imp_dep_mods = mkModDeps dependent_mods,
243 imp_dep_pkgs = dependent_pkgs
246 -- Complain if we import a deprecated module
247 ifOptM Opt_WarnDeprecations (
249 DeprecAll txt -> addWarn (moduleDeprec imp_mod_name txt)
253 let new_imp_decl = L loc (ImportDecl loc_imp_mod_name want_boot
254 qual_only as_mod new_imp_details)
256 returnM (new_imp_decl, gbl_env, imports)
259 warnRedundantSourceImport mod_name
260 = ptext SLIT("Unnecessary {-# SOURCE #-} in the import of module")
261 <+> quotes (ppr mod_name)
265 %************************************************************************
267 importsFromLocalDecls
269 %************************************************************************
271 From the top-level declarations of this module produce
272 * the lexical environment
274 created by its bindings.
276 Complain about duplicate bindings
279 importsFromLocalDecls :: HsGroup RdrName -> RnM TcGblEnv
280 importsFromLocalDecls group
281 = do { gbl_env <- getGblEnv
283 ; avails <- getLocalDeclBinders gbl_env group
285 ; rdr_env' <- extendRdrEnvRn (tcg_rdr_env gbl_env) avails
287 ; traceRn (text "local avails: " <> ppr avails)
289 ; returnM (gbl_env { tcg_rdr_env = rdr_env' })
292 extendRdrEnvRn :: GlobalRdrEnv -> [AvailInfo] -> RnM GlobalRdrEnv
293 -- Add the new locally-bound names one by one, checking for duplicates as
294 -- we do so. Remember that in Template Haskell the duplicates
295 -- might *already be* in the GlobalRdrEnv from higher up the module
296 extendRdrEnvRn rdr_env avails
297 = foldlM add_local rdr_env (gresFromAvails LocalDef avails)
299 add_local rdr_env gre
300 | gres <- lookupGlobalRdrEnv rdr_env (nameOccName (gre_name gre))
301 , (dup_gre:_) <- filter isLocalGRE gres -- Check for existing *local* defns
302 = do { addDupDeclErr (gre_name dup_gre) (gre_name gre)
305 = return (extendGlobalRdrEnv rdr_env gre)
308 @getLocalDeclBinders@ returns the names for an @HsDecl@. It's
309 used for source code.
311 *** See "THE NAMING STORY" in HsDecls ****
313 Instances of indexed types
314 ~~~~~~~~~~~~~~~~~~~~~~~~~~
315 Indexed data/newtype instances contain data constructors that we need to
316 collect, too. Moreover, we need to descend into the data/newtypes instances
317 of associated families.
319 We need to be careful with the handling of the type constructor of each type
320 instance as the family constructor is already defined, and we want to avoid
321 raising a duplicate declaration error. So, we make a new name for it, but
322 don't return it in the 'AvailInfo'.
325 getLocalDeclBinders :: TcGblEnv -> HsGroup RdrName -> RnM [AvailInfo]
326 getLocalDeclBinders gbl_env (HsGroup {hs_valds = ValBindsIn val_decls val_sigs,
327 hs_tyclds = tycl_decls,
328 hs_instds = inst_decls,
329 hs_fords = foreign_decls })
330 = do { tc_names_s <- mappM new_tc tycl_decls
331 ; at_names_s <- mappM inst_ats inst_decls
332 ; val_names <- mappM new_simple val_bndrs
333 ; return (val_names ++ tc_names_s ++ concat at_names_s) }
335 mod = tcg_mod gbl_env
336 is_hs_boot = isHsBoot (tcg_src gbl_env) ;
337 val_bndrs | is_hs_boot = sig_hs_bndrs
338 | otherwise = for_hs_bndrs ++ val_hs_bndrs
339 -- In a hs-boot file, the value binders come from the
340 -- *signatures*, and there should be no foreign binders
342 new_simple rdr_name = do
343 nm <- newTopSrcBinder mod rdr_name
346 sig_hs_bndrs = [nm | L _ (TypeSig nm _) <- val_sigs]
347 val_hs_bndrs = collectHsBindLocatedBinders val_decls
348 for_hs_bndrs = [nm | L _ (ForeignImport nm _ _) <- foreign_decls]
351 | isIdxTyDecl (unLoc tc_decl)
352 = do { main_name <- lookupFamInstDeclBndr mod main_rdr
353 ; sub_names <- mappM (newTopSrcBinder mod) sub_rdrs
354 ; return (AvailTC main_name sub_names) }
355 -- main_name is not bound here!
357 = do { main_name <- newTopSrcBinder mod main_rdr
358 ; sub_names <- mappM (newTopSrcBinder mod) sub_rdrs
359 ; return (AvailTC main_name (main_name : sub_names)) }
361 (main_rdr : sub_rdrs) = tyClDeclNames (unLoc tc_decl)
364 = mappM new_tc (instDeclATs (unLoc inst_decl))
366 getLocalDeclBinders _ _ = panic "getLocalDeclBinders" -- ValBindsOut can't happen
370 %************************************************************************
372 \subsection{Filtering imports}
374 %************************************************************************
376 @filterImports@ takes the @ExportEnv@ telling what the imported module makes
377 available, and filters it through the import spec (if any).
380 filterImports :: ModIface
381 -> ImpDeclSpec -- The span for the entire import decl
382 -> Maybe (Bool, [LIE RdrName]) -- Import spec; True => hiding
383 -> [AvailInfo] -- What's available
384 -> RnM (Maybe (Bool, [LIE Name]), -- Import spec w/ Names
385 GlobalRdrEnv) -- Same again, but in GRE form
387 filterImports iface decl_spec Nothing all_avails
388 = return (Nothing, mkGlobalRdrEnv (gresFromAvails prov all_avails))
390 prov = Imported [ImpSpec { is_decl = decl_spec, is_item = ImpAll }]
393 filterImports iface decl_spec (Just (want_hiding, import_items)) all_avails
394 = do -- check for errors, convert RdrNames to Names
395 opt_indexedtypes <- doptM Opt_IndexedTypes
396 items1 <- mapM (lookup_lie opt_indexedtypes) import_items
398 let items2 :: [(LIE Name, AvailInfo)]
399 items2 = concat items1
400 -- NB the AvailInfo may have duplicates, and several items
401 -- for the same parent; e.g N(x) and N(y)
403 names = availsToNameSet (map snd items2)
404 keep n = not (n `elemNameSet` names)
405 pruned_avails = filterAvails keep all_avails
406 hiding_prov = Imported [ImpSpec { is_decl = decl_spec, is_item = ImpAll }]
408 gres | want_hiding = gresFromAvails hiding_prov pruned_avails
409 | otherwise = concatMap (gresFromIE decl_spec) items2
411 return (Just (want_hiding, map fst items2), mkGlobalRdrEnv gres)
413 -- This environment is how we map names mentioned in the import
414 -- list to the actual Name they correspond to, and the family
415 -- that the Name belongs to (an AvailInfo).
417 -- This env will have entries for data constructors too,
418 -- they won't make any difference because naked entities like T
419 -- in an import list map to TcOccs, not VarOccs.
420 occ_env :: OccEnv (Name,AvailInfo)
421 occ_env = mkOccEnv [ (nameOccName n, (n,a))
422 | a <- all_avails, n <- availNames a ]
424 lookup_lie :: Bool -> LIE RdrName -> TcRn [(LIE Name, AvailInfo)]
425 lookup_lie opt_indexedtypes (L loc ieRdr)
427 stuff <- setSrcSpan loc $
428 case lookup_ie opt_indexedtypes ieRdr of
429 Failed err -> addErr err >> return []
430 Succeeded a -> return a
431 checkDodgyImport stuff
432 return [ (L loc ie, avail) | (ie,avail) <- stuff ]
434 -- Warn when importing T(..) if T was exported abstractly
435 checkDodgyImport stuff
436 | IEThingAll n <- ieRdr, (_, AvailTC _ [one]):_ <- stuff
437 = ifOptM Opt_WarnDodgyImports (addWarn (dodgyImportWarn n))
438 -- NB. use the RdrName for reporting the warning
442 -- For each import item, we convert its RdrNames to Names,
443 -- and at the same time construct an AvailInfo corresponding
444 -- to what is actually imported by this item.
445 -- Returns Nothing on error.
446 -- We return a list here, because in the case of an import
447 -- item like C, if we are hiding, then C refers to *both* a
448 -- type/class and a data constructor.
449 lookup_ie :: Bool -> IE RdrName -> MaybeErr Message [(IE Name,AvailInfo)]
450 lookup_ie opt_indexedtypes ie
451 = let bad_ie = Failed (badImportItemErr iface decl_spec ie)
453 lookup_name rdrName =
454 case lookupOccEnv occ_env (rdrNameOcc rdrName) of
460 (name,avail) <- lookup_name n
461 return [(IEVar name, trimAvail avail name)]
464 (name,avail) <- lookup_name tc
465 return [(IEThingAll name, avail)]
468 | want_hiding -- hiding ( C )
469 -- Here the 'C' can be a data constructor
470 -- *or* a type/class, or even both
471 -> let tc_name = lookup_name tc
472 dc_name = lookup_name (setRdrNameSpace tc srcDataName)
474 case catMaybeErr [ tc_name, dc_name ] of
476 names -> return [ (IEThingAbs n, trimAvail av n)
479 -> do (name,avail) <- lookup_name tc
480 return [(IEThingAbs name, AvailTC name [name])]
482 IEThingWith n ns -> do
483 (name,avail) <- lookup_name n
485 AvailTC nm subnames | nm == name -> do
486 let env = mkOccEnv [ (nameOccName s, s)
488 let mb_children = map (lookupOccEnv env . rdrNameOcc) ns
490 if any isNothing mb_children
492 else return (catMaybes mb_children)
493 -- check for proper import of indexed types
494 when (not opt_indexedtypes && any isTyConName children) $
495 Failed (typeItemErr (head . filter isTyConName
497 (text "in import list"))
498 return [(IEThingWith name children, AvailTC name (name:children))]
502 _other -> Failed illegalImportItemErr
503 -- could be IEModuleContents, IEGroup, IEDoc, IEDocNamed
506 catMaybeErr :: [MaybeErr err a] -> [a]
507 catMaybeErr ms = [ a | Succeeded a <- ms ]
510 %************************************************************************
514 %************************************************************************
517 -- | make a 'GlobalRdrEnv' where all the elements point to the same
518 -- import declaration (useful for "hiding" imports, or imports with
520 gresFromAvails :: Provenance -> [AvailInfo] -> [GlobalRdrElt]
521 gresFromAvails prov avails
522 = concatMap (gresFromAvail (const prov)) avails
524 gresFromAvail :: (Name -> Provenance) -> AvailInfo -> [GlobalRdrElt]
525 gresFromAvail prov_fn avail
526 = [ GRE {gre_name = n,
527 gre_par = availParent n avail,
528 gre_prov = prov_fn n}
529 | n <- availNames avail ]
531 greAvail :: GlobalRdrElt -> AvailInfo
532 greAvail gre = mkUnitAvail (gre_name gre) (gre_par gre)
534 mkUnitAvail :: Name -> Parent -> AvailInfo
535 mkUnitAvail me (ParentIs p) = AvailTC p [me]
536 mkUnitAvail me NoParent | isTyConName me = AvailTC me [me]
537 | otherwise = Avail me
539 plusAvail (Avail n1) (Avail n2) = Avail n1
540 plusAvail (AvailTC n1 ns1) (AvailTC n2 ns2) = AvailTC n2 (ns1 `unionLists` ns2)
541 plusAvail a1 a2 = pprPanic "RnEnv.plusAvail" (hsep [ppr a1,ppr a2])
543 availParent :: Name -> AvailInfo -> Parent
544 availParent n (Avail _) = NoParent
545 availParent n (AvailTC m ms) | n==m = NoParent
546 | otherwise = ParentIs m
548 trimAvail :: AvailInfo -> Name -> AvailInfo
549 trimAvail (Avail n) m = Avail n
550 trimAvail (AvailTC n ns) m = ASSERT( m `elem` ns) AvailTC n [m]
552 -- | filters 'AvailInfo's by the given predicate
553 filterAvails :: (Name -> Bool) -> [AvailInfo] -> [AvailInfo]
554 filterAvails keep avails = foldr (filterAvail keep) [] avails
556 -- | filters an 'AvailInfo' by the given predicate
557 filterAvail :: (Name -> Bool) -> AvailInfo -> [AvailInfo] -> [AvailInfo]
558 filterAvail keep ie rest =
560 Avail n | keep n -> ie : rest
563 let left = filter keep ns in
564 if null left then rest else AvailTC tc left : rest
566 -- | Given an import/export spec, construct the appropriate 'GlobalRdrElt's.
567 gresFromIE :: ImpDeclSpec -> (LIE Name, AvailInfo) -> [GlobalRdrElt]
568 gresFromIE decl_spec (L loc ie, avail)
569 = gresFromAvail prov_fn avail
571 is_explicit = case ie of
572 IEThingAll name -> \n -> n==name
574 prov_fn name = Imported [imp_spec]
576 imp_spec = ImpSpec { is_decl = decl_spec, is_item = item_spec }
577 item_spec = ImpSome { is_explicit = is_explicit name, is_iloc = loc }
579 mkChildEnv :: [GlobalRdrElt] -> NameEnv [Name]
580 mkChildEnv gres = foldr add emptyNameEnv gres
582 add (GRE { gre_name = n, gre_par = ParentIs p }) env = extendNameEnv_C (++) env p [n]
583 add other_gre env = env
585 findChildren :: NameEnv [Name] -> Name -> [Name]
586 findChildren env n = lookupNameEnv env n `orElse` []
589 ---------------------------------------
592 All this AvailEnv stuff is hardly used; only in a very small
593 part of RnNames. Todo: remove?
594 ---------------------------------------
597 type AvailEnv = NameEnv AvailInfo -- Maps a Name to the AvailInfo that contains it
599 emptyAvailEnv :: AvailEnv
600 emptyAvailEnv = emptyNameEnv
602 unitAvailEnv :: AvailInfo -> AvailEnv
603 unitAvailEnv a = unitNameEnv (availName a) a
605 plusAvailEnv :: AvailEnv -> AvailEnv -> AvailEnv
606 plusAvailEnv = plusNameEnv_C plusAvail
608 availEnvElts :: AvailEnv -> [AvailInfo]
609 availEnvElts = nameEnvElts
611 addAvail :: AvailEnv -> AvailInfo -> AvailEnv
612 addAvail avails avail = extendNameEnv_C plusAvail avails (availName avail) avail
614 mkAvailEnv :: [AvailInfo] -> AvailEnv
615 -- 'avails' may have several items with the same availName
616 -- E.g import Ix( Ix(..), index )
617 -- will give Ix(Ix,index,range) and Ix(index)
618 -- We want to combine these; addAvail does that
619 mkAvailEnv avails = foldl addAvail emptyAvailEnv avails
621 -- | combines 'AvailInfo's from the same family
622 nubAvails :: [AvailInfo] -> [AvailInfo]
623 nubAvails avails = nameEnvElts (mkAvailEnv avails)
627 %************************************************************************
629 \subsection{Export list processing}
631 %************************************************************************
633 Processing the export list.
635 You might think that we should record things that appear in the export
636 list as ``occurrences'' (using @addOccurrenceName@), but you'd be
637 wrong. We do check (here) that they are in scope, but there is no
638 need to slurp in their actual declaration (which is what
639 @addOccurrenceName@ forces).
641 Indeed, doing so would big trouble when compiling @PrelBase@, because
642 it re-exports @GHC@, which includes @takeMVar#@, whose type includes
643 @ConcBase.StateAndSynchVar#@, and so on...
646 type ExportAccum -- The type of the accumulating parameter of
647 -- the main worker function in rnExports
648 = ([LIE Name], -- Export items with Names
649 ExportOccMap, -- Tracks exported occurrence names
650 [AvailInfo]) -- The accumulated exported stuff
653 emptyExportAccum = ([], emptyOccEnv, [])
655 type ExportOccMap = OccEnv (Name, IE RdrName)
656 -- Tracks what a particular exported OccName
657 -- in an export list refers to, and which item
658 -- it came from. It's illegal to export two distinct things
659 -- that have the same occurrence name
661 rnExports :: Bool -- False => no 'module M(..) where' header at all
662 -> Maybe [LIE RdrName] -- Nothing => no explicit export list
663 -> RnM (Maybe [LIE Name], [AvailInfo])
665 -- Complains if two distinct exports have same OccName
666 -- Warns about identical exports.
667 -- Complains about exports items not in scope
669 rnExports explicit_mod exports
670 = do TcGblEnv { tcg_mod = this_mod,
671 tcg_rdr_env = rdr_env,
672 tcg_imports = imports } <- getGblEnv
674 -- If the module header is omitted altogether, then behave
675 -- as if the user had written "module Main(main) where..."
676 -- EXCEPT in interactive mode, when we behave as if he had
677 -- written "module Main where ..."
678 -- Reason: don't want to complain about 'main' not in scope
679 -- in interactive mode
680 ghc_mode <- getGhcMode
685 | ghc_mode == Interactive
688 -> do mainName <- lookupGlobalOccRn main_RDR_Unqual
689 return (Just ([noLoc (IEVar main_RDR_Unqual)]))
690 -- ToDo: the 'noLoc' here is unhelpful if 'main' turns
691 -- out to be out of scope
693 (exp_spec, avails) <- exports_from_avail real_exports rdr_env imports this_mod
695 return (exp_spec, nubAvails avails) -- Combine families
697 exports_from_avail :: Maybe [LIE RdrName]
698 -- Nothing => no explicit export list
702 -> RnM (Maybe [LIE Name], [AvailInfo])
704 exports_from_avail Nothing rdr_env imports this_mod
705 = -- The same as (module M) where M is the current module name,
706 -- so that's how we handle it.
708 avails = [ greAvail gre | gre <- globalRdrEnvElts rdr_env,
711 return (Nothing, avails)
713 exports_from_avail (Just rdr_items) rdr_env imports this_mod
714 = do (ie_names, _, exports) <- foldlM do_litem emptyExportAccum rdr_items
715 return (Just ie_names, exports)
717 do_litem :: ExportAccum -> LIE RdrName -> RnM ExportAccum
718 do_litem acc lie = setSrcSpan (getLoc lie) (exports_from_item acc lie)
720 kids_env :: NameEnv [Name] -- Maps a parent to its in-scope children
721 kids_env = mkChildEnv (globalRdrEnvElts rdr_env)
723 exports_from_item :: ExportAccum -> LIE RdrName -> RnM ExportAccum
724 exports_from_item acc@(ie_names, occs, exports)
725 (L loc ie@(IEModuleContents mod))
726 | let earlier_mods = [ mod | (L _ (IEModuleContents mod)) <- ie_names ]
727 , mod `elem` earlier_mods -- Duplicate export of M
728 = do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
729 warnIf warn_dup_exports (dupModuleExport mod) ;
733 = do { implicit_prelude <- doptM Opt_ImplicitPrelude
734 ; let gres = filter (isModuleExported implicit_prelude mod)
735 (globalRdrEnvElts rdr_env)
737 ; warnIf (null gres) (nullModuleExport mod)
739 ; occs' <- check_occs ie occs (map gre_name gres)
740 -- This check_occs not only finds conflicts
741 -- between this item and others, but also
742 -- internally within this item. That is, if
743 -- 'M.x' is in scope in several ways, we'll have
744 -- several members of mod_avails with the same
746 ; return (L loc (IEModuleContents mod) : ie_names,
747 occs', map greAvail gres ++ exports) }
749 exports_from_item acc@(lie_names, occs, exports) (L loc ie)
751 = do new_ie <- lookup_doc_ie ie
752 return (L loc new_ie : lie_names, occs, exports)
755 = do (new_ie, avail) <- lookup_ie ie
756 if isUnboundName (ieName new_ie)
757 then return acc -- Avoid error cascade
760 occs' <- check_occs ie occs (availNames avail)
762 return (L loc new_ie : lie_names, occs', avail : exports)
765 lookup_ie :: IE RdrName -> RnM (IE Name, AvailInfo)
766 lookup_ie (IEVar rdr)
767 = do gre <- lookupGreRn rdr
768 return (IEVar (gre_name gre), greAvail gre)
770 lookup_ie (IEThingAbs rdr)
771 = do name <- lookupGlobalOccRn rdr
772 return (IEThingAbs name, AvailTC name [name])
774 lookup_ie ie@(IEThingAll rdr)
775 = do name <- lookupGlobalOccRn rdr
776 let kids = findChildren kids_env name
778 (if (isTyConName name) then addWarn (dodgyExportWarn name)
779 -- This occurs when you export T(..), but
780 -- only import T abstractly, or T is a synonym.
781 else addErr (exportItemErr ie))
783 return (IEThingAll name, AvailTC name (name:kids))
785 lookup_ie ie@(IEThingWith rdr sub_rdrs)
786 = do name <- lookupGlobalOccRn rdr
787 if isUnboundName name
788 then return (IEThingWith name [], AvailTC name [name])
790 let env = mkOccEnv [ (nameOccName s, s)
791 | s <- findChildren kids_env name ]
792 mb_names = map (lookupOccEnv env . rdrNameOcc) sub_rdrs
793 if any isNothing mb_names
794 then do addErr (exportItemErr ie)
795 return (IEThingWith name [], AvailTC name [name])
796 else do let names = catMaybes mb_names
797 optIdxTypes <- doptM Opt_IndexedTypes
798 when (not optIdxTypes && any isTyConName names) $
799 addErr (typeItemErr ( head
802 (text "in export list"))
803 return (IEThingWith name names, AvailTC name (name:names))
805 lookup_ie ie = panic "lookup_ie" -- Other cases covered earlier
808 lookup_doc_ie :: IE RdrName -> RnM (IE Name)
809 lookup_doc_ie (IEGroup lev doc) = do rn_doc <- rnHsDoc doc
810 return (IEGroup lev rn_doc)
811 lookup_doc_ie (IEDoc doc) = do rn_doc <- rnHsDoc doc
812 return (IEDoc rn_doc)
813 lookup_doc_ie (IEDocNamed str) = return (IEDocNamed str)
814 lookup_doc_ie ie = panic "lookup_doc_ie" -- Other cases covered earlier
817 isDoc (IEDoc _) = True
818 isDoc (IEDocNamed _) = True
819 isDoc (IEGroup _ _) = True
822 -------------------------------
823 isModuleExported :: Bool -> ModuleName -> GlobalRdrElt -> Bool
824 -- True if the thing is in scope *both* unqualified, *and* with qualifier M
825 isModuleExported implicit_prelude mod (GRE { gre_name = name, gre_prov = prov })
826 | implicit_prelude && isBuiltInSyntax name = False
827 -- Optimisation: filter out names for built-in syntax
828 -- They just clutter up the environment (esp tuples), and the parser
829 -- will generate Exact RdrNames for them, so the cluttered
830 -- envt is no use. To avoid doing this filter all the time,
831 -- we use -fno-implicit-prelude as a clue that the filter is
832 -- worth while. Really, it's only useful for GHC.Base and GHC.Tuple.
834 -- It's worth doing because it makes the environment smaller for
835 -- every module that imports the Prelude
838 LocalDef -> moduleName (nameModule name) == mod
839 Imported is -> any unQualSpecOK is && any (qualSpecOK mod) is
841 -------------------------------
842 check_occs :: IE RdrName -> ExportOccMap -> [Name] -> RnM ExportOccMap
843 check_occs ie occs names
844 = foldlM check occs names
847 = case lookupOccEnv occs name_occ of
848 Nothing -> returnM (extendOccEnv occs name_occ (name, ie))
851 | name == name' -- Duplicate export
852 -> do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
853 warnIf warn_dup_exports (dupExportWarn name_occ ie ie') ;
856 | otherwise -- Same occ name but different names: an error
857 -> do { global_env <- getGlobalRdrEnv ;
858 addErr (exportClashErr global_env name' name ie' ie) ;
861 name_occ = nameOccName name
864 %*********************************************************
868 %*********************************************************
871 reportDeprecations :: DynFlags -> TcGblEnv -> RnM ()
872 reportDeprecations dflags tcg_env
873 = ifOptM Opt_WarnDeprecations $
874 do { (eps,hpt) <- getEpsAndHpt
875 -- By this time, typechecking is complete,
876 -- so the PIT is fully populated
877 ; mapM_ (check hpt (eps_PIT eps)) all_gres }
879 used_names = allUses (tcg_dus tcg_env)
880 -- Report on all deprecated uses; hence allUses
881 all_gres = globalRdrEnvElts (tcg_rdr_env tcg_env)
883 check hpt pit gre@(GRE {gre_name = name, gre_prov = Imported (imp_spec:_)})
884 | name `elemNameSet` used_names
885 , Just deprec_txt <- lookupDeprec dflags hpt pit gre
886 = addWarnAt (importSpecLoc imp_spec)
887 (sep [ptext SLIT("Deprecated use of") <+>
888 pprNonVarNameSpace (occNameSpace (nameOccName name)) <+>
890 (parens imp_msg) <> colon,
893 name_mod = nameModule name
894 imp_mod = importSpecModule imp_spec
895 imp_msg = ptext SLIT("imported from") <+> ppr imp_mod <> extra
896 extra | imp_mod == moduleName name_mod = empty
897 | otherwise = ptext SLIT(", but defined in") <+> ppr name_mod
899 check hpt pit ok_gre = returnM () -- Local, or not used, or not deprectated
900 -- The Imported pattern-match: don't deprecate locally defined names
901 -- For a start, we may be exporting a deprecated thing
902 -- Also we may use a deprecated thing in the defn of another
903 -- deprecated things. We may even use a deprecated thing in
904 -- the defn of a non-deprecated thing, when changing a module's
907 lookupDeprec :: DynFlags -> HomePackageTable -> PackageIfaceTable
908 -> GlobalRdrElt -> Maybe DeprecTxt
909 lookupDeprec dflags hpt pit gre
910 = case lookupIfaceByModule dflags hpt pit (nameModule name) of
911 Just iface -> mi_dep_fn iface name `seqMaybe` -- Bleat if the thing, *or
913 ParentIs p -> mi_dep_fn iface p -- its parent*, is deprec'd
916 | isWiredInName name -> Nothing
917 -- We have not necessarily loaded the .hi file for a
918 -- wired-in name (yet), although we *could*.
919 -- And we never deprecate them
921 | otherwise -> pprPanic "lookupDeprec" (ppr name)
922 -- By now all the interfaces should have been loaded
927 %*********************************************************
931 %*********************************************************
934 reportUnusedNames :: Maybe [LIE RdrName] -- Export list
935 -> TcGblEnv -> RnM ()
936 reportUnusedNames export_decls gbl_env
937 = do { traceRn ((text "RUN") <+> (ppr (tcg_dus gbl_env)))
938 ; warnUnusedTopBinds unused_locals
939 ; warnUnusedModules unused_imp_mods
940 ; warnUnusedImports unused_imports
941 ; warnDuplicateImports defined_and_used
942 ; printMinimalImports minimal_imports }
944 used_names :: NameSet
945 used_names = findUses (tcg_dus gbl_env) emptyNameSet
946 -- NB: currently, if f x = g, we only treat 'g' as used if 'f' is used
949 -- Collect the defined names from the in-scope environment
950 defined_names :: [GlobalRdrElt]
951 defined_names = globalRdrEnvElts (tcg_rdr_env gbl_env)
953 -- Note that defined_and_used, defined_but_not_used
954 -- are both [GRE]; that's why we need defined_and_used
955 -- rather than just used_names
956 defined_and_used, defined_but_not_used :: [GlobalRdrElt]
957 (defined_and_used, defined_but_not_used)
958 = partition (gre_is_used used_names) defined_names
960 kids_env = mkChildEnv defined_names
961 -- This is done in mkExports too; duplicated work
963 gre_is_used :: NameSet -> GlobalRdrElt -> Bool
964 gre_is_used used_names (GRE {gre_name = name})
965 = name `elemNameSet` used_names
966 || any (`elemNameSet` used_names) (findChildren kids_env name)
967 -- A use of C implies a use of T,
968 -- if C was brought into scope by T(..) or T(C)
970 -- Filter out the ones that are
971 -- (a) defined in this module, and
972 -- (b) not defined by a 'deriving' clause
973 -- The latter have an Internal Name, so we can filter them out easily
974 unused_locals :: [GlobalRdrElt]
975 unused_locals = filter is_unused_local defined_but_not_used
976 is_unused_local :: GlobalRdrElt -> Bool
977 is_unused_local gre = isLocalGRE gre && isExternalName (gre_name gre)
979 unused_imports :: [GlobalRdrElt]
980 unused_imports = filter unused_imp defined_but_not_used
981 unused_imp (GRE {gre_prov = Imported imp_specs})
982 = not (all (module_unused . importSpecModule) imp_specs)
983 && or [exp | ImpSpec { is_item = ImpSome { is_explicit = exp } } <- imp_specs]
984 -- Don't complain about unused imports if we've already said the
985 -- entire import is unused
986 unused_imp other = False
988 -- To figure out the minimal set of imports, start with the things
989 -- that are in scope (i.e. in gbl_env). Then just combine them
990 -- into a bunch of avails, so they are properly grouped
992 -- BUG WARNING: this does not deal properly with qualified imports!
993 minimal_imports :: FiniteMap ModuleName AvailEnv
994 minimal_imports0 = foldr add_expall emptyFM expall_mods
995 minimal_imports1 = foldr add_name minimal_imports0 defined_and_used
996 minimal_imports = foldr add_inst_mod minimal_imports1 direct_import_mods
997 -- The last line makes sure that we retain all direct imports
998 -- even if we import nothing explicitly.
999 -- It's not necessarily redundant to import such modules. Consider
1003 -- The import M() is not *necessarily* redundant, even if
1004 -- we suck in no instance decls from M (e.g. it contains
1005 -- no instance decls, or This contains no code). It may be
1006 -- that we import M solely to ensure that M's orphan instance
1007 -- decls (or those in its imports) are visible to people who
1008 -- import This. Sigh.
1009 -- There's really no good way to detect this, so the error message
1010 -- in RnEnv.warnUnusedModules is weakened instead
1012 -- We've carefully preserved the provenance so that we can
1013 -- construct minimal imports that import the name by (one of)
1014 -- the same route(s) as the programmer originally did.
1015 add_name gre@(GRE {gre_prov = Imported (imp_spec:_)}) acc
1016 = addToFM_C plusAvailEnv acc
1017 (importSpecModule imp_spec) (unitAvailEnv (greAvail gre))
1018 add_name gre acc = acc -- Local
1020 -- Modules mentioned as 'module M' in the export list
1021 expall_mods = case export_decls of
1023 Just es -> [m | L _ (IEModuleContents m) <- es]
1025 -- This is really bogus. The idea is that if we see 'module M' in
1026 -- the export list we must retain the import decls that drive it
1027 -- If we aren't careful we might see
1028 -- module A( module M ) where
1031 -- and suppose that N exports everything that M does. Then we
1032 -- must not drop the import of M even though N brings it all into
1035 -- BUG WARNING: 'module M' exports aside, what if M.x is mentioned?!
1037 -- The reason that add_expall is bogus is that it doesn't take
1038 -- qualified imports into account. But it's an improvement.
1039 add_expall mod acc = addToFM_C plusAvailEnv acc mod emptyAvailEnv
1041 add_inst_mod (mod,_,_) acc
1042 | mod_name `elemFM` acc = acc -- We import something already
1043 | otherwise = addToFM acc mod_name emptyAvailEnv
1045 mod_name = moduleName mod
1046 -- Add an empty collection of imports for a module
1047 -- from which we have sucked only instance decls
1049 imports = tcg_imports gbl_env
1051 direct_import_mods :: [(Module, Bool, SrcSpan)]
1052 -- See the type of the imp_mods for this triple
1053 direct_import_mods = moduleEnvElts (imp_mods imports)
1055 -- unused_imp_mods are the directly-imported modules
1056 -- that are not mentioned in minimal_imports1
1057 -- [Note: not 'minimal_imports', because that includes directly-imported
1058 -- modules even if we use nothing from them; see notes above]
1060 -- BUG WARNING: does not deal correctly with multiple imports of the same module
1061 -- becuase direct_import_mods has only one entry per module
1062 unused_imp_mods = [(mod_name,loc) | (mod,no_imp,loc) <- direct_import_mods,
1063 let mod_name = moduleName mod,
1064 not (mod_name `elemFM` minimal_imports1),
1067 -- The not no_imp part is not to complain about
1068 -- import M (), which is an idiom for importing
1069 -- instance declarations
1071 module_unused :: ModuleName -> Bool
1072 module_unused mod = any (((==) mod) . fst) unused_imp_mods
1074 ---------------------
1075 warnDuplicateImports :: [GlobalRdrElt] -> RnM ()
1076 -- Given the GREs for names that are used, figure out which imports
1077 -- could be omitted without changing the top-level environment.
1079 -- NB: Given import Foo( T )
1080 -- import qualified Foo
1081 -- we do not report a duplicate import, even though Foo.T is brought
1082 -- into scope by both, because there's nothing you can *omit* without
1083 -- changing the top-level environment. So we complain only if it's
1084 -- explicitly named in both imports or neither.
1086 -- Furthermore, we complain about Foo.T only if
1087 -- there is no complaint about (unqualified) T
1089 warnDuplicateImports gres
1090 = ifOptM Opt_WarnUnusedImports $
1091 sequenceM_ [ warn name pr
1092 -- The 'head' picks the first offending group
1093 -- for this particular name
1094 | GRE { gre_name = name, gre_prov = Imported imps } <- gres
1095 , pr <- redundants imps ]
1097 warn name (red_imp, cov_imp)
1098 = addWarnAt (importSpecLoc red_imp)
1099 (vcat [ptext SLIT("Redundant import of:") <+> quotes pp_name,
1100 ptext SLIT("It is also") <+> ppr cov_imp])
1102 pp_name | is_qual red_decl = ppr (is_as red_decl) <> dot <> ppr occ
1103 | otherwise = ppr occ
1104 occ = nameOccName name
1105 red_decl = is_decl red_imp
1107 redundants :: [ImportSpec] -> [(ImportSpec,ImportSpec)]
1108 -- The returned pair is (redundant-import, covering-import)
1110 = [ (red_imp, cov_imp)
1112 , cov_imp <- take 1 (filter (covers red_imp) imps) ]
1114 -- "red_imp" is a putative redundant import
1115 -- "cov_imp" potentially covers it
1116 -- This test decides whether red_imp could be dropped
1118 -- NOTE: currently the test does not warn about
1121 -- even if the same underlying 'x' is involved, because dropping
1122 -- either import would change the qualified names in scope (M.x, N.x)
1123 -- But if the qualified names aren't used, the import is indeed redundant
1124 -- Sadly we don't know that. Oh well.
1125 covers red_imp@(ImpSpec { is_decl = red_decl, is_item = red_item })
1126 cov_imp@(ImpSpec { is_decl = cov_decl, is_item = cov_item })
1127 | red_loc == cov_loc
1128 = False -- Ignore diagonal elements
1129 | not (is_as red_decl == is_as cov_decl)
1130 = False -- They bring into scope different qualified names
1131 | not (is_qual red_decl) && is_qual cov_decl
1132 = False -- Covering one doesn't bring unqualified name into scope
1134 = not cov_selective -- Redundant one is selective and covering one isn't
1135 || red_later -- Both are explicit; tie-break using red_later
1137 = not cov_selective -- Neither import is selective
1138 && (is_mod red_decl == is_mod cov_decl) -- They import the same module
1139 && red_later -- Tie-break
1141 red_loc = importSpecLoc red_imp
1142 cov_loc = importSpecLoc cov_imp
1143 red_later = red_loc > cov_loc
1144 cov_selective = selectiveImpItem cov_item
1145 red_selective = selectiveImpItem red_item
1147 selectiveImpItem :: ImpItemSpec -> Bool
1148 selectiveImpItem ImpAll = False
1149 selectiveImpItem (ImpSome {}) = True
1151 -- ToDo: deal with original imports with 'qualified' and 'as M' clauses
1152 printMinimalImports :: FiniteMap ModuleName AvailEnv -- Minimal imports
1154 printMinimalImports imps
1155 = ifOptM Opt_D_dump_minimal_imports $ do {
1157 mod_ies <- mappM to_ies (fmToList imps) ;
1158 this_mod <- getModule ;
1159 rdr_env <- getGlobalRdrEnv ;
1160 ioToTcRn (do { h <- openFile (mkFilename this_mod) WriteMode ;
1161 printForUser h (mkPrintUnqualified rdr_env)
1162 (vcat (map ppr_mod_ie mod_ies)) })
1165 mkFilename this_mod = moduleNameString (moduleName this_mod) ++ ".imports"
1166 ppr_mod_ie (mod_name, ies)
1167 | mod_name == moduleName pRELUDE
1169 | null ies -- Nothing except instances comes from here
1170 = ptext SLIT("import") <+> ppr mod_name <> ptext SLIT("() -- Instances only")
1172 = ptext SLIT("import") <+> ppr mod_name <>
1173 parens (fsep (punctuate comma (map ppr ies)))
1175 to_ies (mod, avail_env) = do ies <- mapM to_ie (availEnvElts avail_env)
1178 to_ie :: AvailInfo -> RnM (IE Name)
1179 -- The main trick here is that if we're importing all the constructors
1180 -- we want to say "T(..)", but if we're importing only a subset we want
1181 -- to say "T(A,B,C)". So we have to find out what the module exports.
1182 to_ie (Avail n) = returnM (IEVar n)
1183 to_ie (AvailTC n [m]) = ASSERT( n==m )
1184 returnM (IEThingAbs n)
1185 to_ie (AvailTC n ns)
1186 = loadSrcInterface doc n_mod False `thenM` \ iface ->
1187 case [xs | (m,as) <- mi_exports iface,
1188 moduleName m == n_mod,
1190 x == nameOccName n] of
1191 [xs] | all_used xs -> returnM (IEThingAll n)
1192 | otherwise -> returnM (IEThingWith n (filter (/= n) ns))
1193 other -> pprTrace "to_ie" (ppr n <+> ppr n_mod <+> ppr other) $
1196 all_used avail_occs = all (`elem` map nameOccName ns) avail_occs
1197 doc = text "Compute minimal imports from" <+> ppr n
1198 n_mod = moduleName (nameModule n)
1202 %************************************************************************
1206 %************************************************************************
1209 badImportItemErr iface decl_spec ie
1210 = sep [ptext SLIT("Module"), quotes (ppr (is_mod decl_spec)), source_import,
1211 ptext SLIT("does not export"), quotes (ppr ie)]
1213 source_import | mi_boot iface = ptext SLIT("(hi-boot interface)")
1216 illegalImportItemErr = ptext SLIT("Illegal import item")
1218 dodgyImportWarn item = dodgyMsg (ptext SLIT("import")) item
1219 dodgyExportWarn item = dodgyMsg (ptext SLIT("export")) item
1222 = sep [ ptext SLIT("The") <+> kind <+> ptext SLIT("item") <+> quotes (ppr (IEThingAll tc)),
1223 ptext SLIT("suggests that") <+> quotes (ppr tc) <+> ptext SLIT("has constructor or class methods"),
1224 ptext SLIT("but it has none; it is a type synonym or abstract type or class") ]
1226 exportItemErr export_item
1227 = sep [ ptext SLIT("The export item") <+> quotes (ppr export_item),
1228 ptext SLIT("attempts to export constructors or class methods that are not visible here") ]
1230 typeItemErr name wherestr
1231 = sep [ ptext SLIT("Using 'type' tag on") <+> quotes (ppr name) <+> wherestr,
1232 ptext SLIT("Use -findexed-types to enable this extension") ]
1234 exportClashErr global_env name1 name2 ie1 ie2
1235 = vcat [ ptext SLIT("Conflicting exports for") <+> quotes (ppr occ) <> colon
1236 , ppr_export ie1 name1
1237 , ppr_export ie2 name2 ]
1239 occ = nameOccName name1
1240 ppr_export ie name = nest 2 (quotes (ppr ie) <+> ptext SLIT("exports") <+>
1241 quotes (ppr name) <+> pprNameProvenance (get_gre name))
1243 -- get_gre finds a GRE for the Name, so that we can show its provenance
1245 = case lookupGRE_Name global_env name of
1247 [] -> pprPanic "exportClashErr" (ppr name)
1249 addDupDeclErr :: Name -> Name -> TcRn ()
1250 addDupDeclErr name_a name_b
1251 = addErrAt (srcLocSpan loc2) $
1252 vcat [ptext SLIT("Multiple declarations of") <+> quotes (ppr name1),
1253 ptext SLIT("Declared at:") <+> vcat [ppr (nameSrcLoc name1), ppr loc2]]
1255 loc2 = nameSrcLoc name2
1256 (name1,name2) | nameSrcLoc name_a > nameSrcLoc name_b = (name_b,name_a)
1257 | otherwise = (name_a,name_b)
1258 -- Report the error at the later location
1260 dupExportWarn occ_name ie1 ie2
1261 = hsep [quotes (ppr occ_name),
1262 ptext SLIT("is exported by"), quotes (ppr ie1),
1263 ptext SLIT("and"), quotes (ppr ie2)]
1266 = hsep [ptext SLIT("Duplicate"),
1267 quotes (ptext SLIT("Module") <+> ppr mod),
1268 ptext SLIT("in export list")]
1270 nullModuleExport mod
1271 = ptext SLIT("The export item `module") <+> ppr mod <> ptext SLIT("' exports nothing")
1273 moduleDeprec mod txt
1274 = sep [ ptext SLIT("Module") <+> quotes (ppr mod) <+> ptext SLIT("is deprecated:"),