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,
15 #include "HsVersions.h"
17 import DynFlags ( DynFlag(..), GhcMode(..) )
18 import HsSyn ( IE(..), ieName, ImportDecl(..), LImportDecl,
19 ForeignDecl(..), HsGroup(..), HsValBinds(..),
20 Sig(..), collectHsBindLocatedBinders, tyClDeclNames
23 import IfaceEnv ( ifaceExportNames )
24 import LoadIface ( loadSrcInterface )
28 import PrelNames ( pRELUDE, isUnboundName, main_RDR_Unqual )
29 import Module ( Module, moduleUserString, unitModuleEnv,
30 lookupModuleEnv, moduleEnvElts, foldModuleEnv )
31 import Name ( Name, nameSrcLoc, nameOccName, nameModule, isWiredInName,
32 nameParent, nameParent_maybe, isExternalName,
36 import OccName ( srcDataName, isTcOcc, occNameFlavour, OccEnv,
37 mkOccEnv, lookupOccEnv, emptyOccEnv, extendOccEnv )
38 import HscTypes ( GenAvailInfo(..), AvailInfo,
39 HomePackageTable, PackageIfaceTable,
41 Deprecs(..), ModIface(..), Dependencies(..),
42 lookupIface, ExternalPackageState(..)
44 import Packages ( PackageIdH(..) )
45 import RdrName ( RdrName, rdrNameOcc, setRdrNameSpace,
46 GlobalRdrEnv, mkGlobalRdrEnv, GlobalRdrElt(..),
47 emptyGlobalRdrEnv, plusGlobalRdrEnv, globalRdrEnvElts,
48 extendGlobalRdrEnv, lookupGlobalRdrEnv, unQualOK, lookupGRE_Name,
49 Provenance(..), ImportSpec(..), ImpDeclSpec(..), ImpItemSpec(..),
50 importSpecLoc, importSpecModule, isLocalGRE, pprNameProvenance )
52 import Maybes ( isNothing, catMaybes, mapCatMaybes, seqMaybe, orElse )
53 import SrcLoc ( Located(..), mkGeneralSrcSpan,
54 unLoc, noLoc, srcLocSpan, SrcSpan )
55 import BasicTypes ( DeprecTxt )
56 import DriverPhases ( isHsBoot )
57 import Util ( notNull )
58 import List ( partition )
59 import IO ( openFile, IOMode(..) )
64 %************************************************************************
68 %************************************************************************
71 rnImports :: [LImportDecl RdrName]
72 -> RnM (GlobalRdrEnv, ImportAvails)
75 = do { -- PROCESS IMPORT DECLS
76 -- Do the non {- SOURCE -} ones first, so that we get a helpful
77 -- warning for {- SOURCE -} ones that are unnecessary
79 ; implicit_prelude <- doptM Opt_ImplicitPrelude
81 all_imports = mk_prel_imports this_mod implicit_prelude ++ imports
82 (source, ordinary) = partition is_source_import all_imports
83 is_source_import (L _ (ImportDecl _ is_boot _ _ _)) = is_boot
85 get_imports = importsFromImportDecl this_mod
87 ; stuff1 <- mappM get_imports ordinary
88 ; stuff2 <- mappM get_imports source
92 (imp_gbl_envs, imp_avails) = unzip (stuff1 ++ stuff2)
93 gbl_env :: GlobalRdrEnv
94 gbl_env = foldr plusGlobalRdrEnv emptyGlobalRdrEnv imp_gbl_envs
96 all_avails :: ImportAvails
97 all_avails = foldr plusImportAvails emptyImportAvails imp_avails
100 ; return (gbl_env, all_avails) }
102 -- NB: opt_NoImplicitPrelude is slightly different to import Prelude ();
103 -- because the former doesn't even look at Prelude.hi for instance
104 -- declarations, whereas the latter does.
105 mk_prel_imports this_mod implicit_prelude
106 | this_mod == pRELUDE
107 || explicit_prelude_import
108 || not implicit_prelude
111 | otherwise = [preludeImportDecl]
113 explicit_prelude_import
114 = notNull [ () | L _ (ImportDecl mod _ _ _ _) <- imports,
115 unLoc mod == pRELUDE ]
119 ImportDecl (L loc pRELUDE)
120 False {- Not a boot interface -}
121 False {- Not qualified -}
122 Nothing {- No "as" -}
123 Nothing {- No import list -}
125 loc = mkGeneralSrcSpan FSLIT("Implicit import declaration")
129 importsFromImportDecl :: Module
130 -> LImportDecl RdrName
131 -> RnM (GlobalRdrEnv, ImportAvails)
133 importsFromImportDecl this_mod
134 (L loc (ImportDecl loc_imp_mod_name want_boot qual_only as_mod imp_details))
138 -- If there's an error in loadInterface, (e.g. interface
139 -- file not found) we get lots of spurious errors from 'filterImports'
141 imp_mod_name = unLoc loc_imp_mod_name
142 doc = ppr imp_mod_name <+> ptext SLIT("is directly imported")
144 loadSrcInterface doc imp_mod_name want_boot `thenM` \ iface ->
146 -- Compiler sanity check: if the import didn't say
147 -- {-# SOURCE #-} we should not get a hi-boot file
148 WARN( not want_boot && mi_boot iface, ppr imp_mod_name )
150 -- Issue a user warning for a redundant {- SOURCE -} import
151 -- NB that we arrange to read all the ordinary imports before
152 -- any of the {- SOURCE -} imports
153 warnIf (want_boot && not (mi_boot iface))
154 (warnRedundantSourceImport imp_mod_name) `thenM_`
157 imp_mod = mi_module iface
158 deprecs = mi_deprecs iface
159 is_orph = mi_orphan 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 ignore it.
165 -- Reason: otherwise it looks as if there are two local definition sites
166 -- for the thing, and an error gets reported. Easiest thing is just to
167 -- filter them out up front. This situation only arises if a module
168 -- imports itself, or another module that imported it. (Necessarily,
169 -- this invoves a loop.)
171 -- Tiresome consequence: if you say
176 -- module B( AType ) where
177 -- import {-# SOURCE #-} A( AType )
179 -- then you'll get a 'B does not export AType' message. Oh well.
181 qual_mod_name = case as_mod of
182 Nothing -> imp_mod_name
183 Just another_name -> another_name
184 imp_spec = ImpDeclSpec { is_mod = imp_mod_name, is_qual = qual_only,
185 is_dloc = loc, is_as = qual_mod_name }
187 -- Get the total imports, and filter them according to the import list
188 ifaceExportNames filtered_exports `thenM` \ total_avails ->
189 filterImports iface imp_spec
190 imp_details total_avails `thenM` \ (avail_env, gbl_env) ->
192 getDOpts `thenM` \ dflags ->
195 -- Compute new transitive dependencies
197 orphans | is_orph = ASSERT( not (imp_mod_name `elem` dep_orphs deps) )
198 imp_mod_name : dep_orphs deps
199 | otherwise = dep_orphs deps
201 (dependent_mods, dependent_pkgs)
202 = case mi_package iface of
204 -- Imported module is from the home package
205 -- Take its dependent modules and add imp_mod itself
206 -- Take its dependent packages unchanged
208 -- NB: (dep_mods deps) might include a hi-boot file
209 -- for the module being compiled, CM. Do *not* filter
210 -- this out (as we used to), because when we've
211 -- finished dealing with the direct imports we want to
212 -- know if any of them depended on CM.hi-boot, in
213 -- which case we should do the hi-boot consistency
214 -- check. See LoadIface.loadHiBootInterface
215 ((imp_mod_name, want_boot) : dep_mods deps, dep_pkgs deps)
218 -- Imported module is from another package
219 -- Dump the dependent modules
220 -- Add the package imp_mod comes from to the dependent packages
221 ASSERT2( not (pkg `elem` dep_pkgs deps), ppr pkg <+> ppr (dep_pkgs deps) )
222 ([], pkg : dep_pkgs deps)
224 -- True <=> import M ()
225 import_all = case imp_details of
226 Just (is_hiding, ls) -> not is_hiding && null ls
229 -- unqual_avails is the Avails that are visible in *unqualified* form
230 -- We need to know this so we know what to export when we see
231 -- module M ( module P ) where ...
232 -- Then we must export whatever came from P unqualified.
233 imports = ImportAvails {
234 imp_env = unitModuleEnv qual_mod_name avail_env,
235 imp_mods = unitModuleEnv imp_mod (imp_mod, import_all, loc),
237 imp_dep_mods = mkModDeps dependent_mods,
238 imp_dep_pkgs = dependent_pkgs }
241 -- Complain if we import a deprecated module
242 ifOptM Opt_WarnDeprecations (
244 DeprecAll txt -> addWarn (moduleDeprec imp_mod_name txt)
248 returnM (gbl_env, imports)
250 warnRedundantSourceImport mod_name
251 = ptext SLIT("Unnecessary {- SOURCE -} in the import of module")
252 <+> quotes (ppr mod_name)
256 %************************************************************************
258 importsFromLocalDecls
260 %************************************************************************
262 From the top-level declarations of this module produce
263 * the lexical environment
265 created by its bindings.
267 Complain about duplicate bindings
270 importsFromLocalDecls :: HsGroup RdrName -> RnM TcGblEnv
271 importsFromLocalDecls group
272 = do { gbl_env <- getGblEnv
274 ; names <- getLocalDeclBinders gbl_env group
276 ; implicit_prelude <- doptM Opt_ImplicitPrelude
278 -- Optimisation: filter out names for built-in syntax
279 -- They just clutter up the environment (esp tuples), and the parser
280 -- will generate Exact RdrNames for them, so the cluttered
281 -- envt is no use. To avoid doing this filter all the time,
282 -- we use -fno-implicit-prelude as a clue that the filter is
283 -- worth while. Really, it's only useful for GHC.Base and GHC.Tuple.
285 -- It's worth doing because it makes the environment smaller for
286 -- every module that imports the Prelude
288 -- Note: don't filter the gbl_env (hence all_names, not filered_all_names
289 -- in defn of gres above). Stupid reason: when parsing
290 -- data type decls, the constructors start as Exact tycon-names,
291 -- and then get turned into data con names by zapping the name space;
292 -- but that stops them being Exact, so they get looked up.
293 -- Ditto in fixity decls; e.g. infix 5 :
294 -- Sigh. It doesn't matter because it only affects the Data.Tuple really.
295 -- The important thing is to trim down the exports.
297 | implicit_prelude = names
298 | otherwise = filter (not . isBuiltInSyntax) names ;
300 ; this_mod = tcg_mod gbl_env
301 ; imports = emptyImportAvails {
302 imp_env = unitModuleEnv this_mod $
303 mkNameSet filtered_names
307 ; rdr_env' <- extendRdrEnvRn (tcg_rdr_env gbl_env) names
309 ; returnM (gbl_env { tcg_rdr_env = rdr_env',
310 tcg_imports = imports `plusImportAvails` tcg_imports gbl_env })
313 extendRdrEnvRn :: GlobalRdrEnv -> [Name] -> RnM GlobalRdrEnv
314 -- Add the new locally-bound names one by one, checking for duplicates as
315 -- we do so. Remember that in Template Haskell the duplicates
316 -- might *already be* in the GlobalRdrEnv from higher up the module
317 extendRdrEnvRn rdr_env names
318 = foldlM add_local rdr_env names
320 add_local rdr_env name
321 | gres <- lookupGlobalRdrEnv rdr_env (nameOccName name)
322 , (dup_gre:_) <- filter isLocalGRE gres -- Check for existing *local* defns
323 = do { addDupDeclErr (gre_name dup_gre) name
326 = return (extendGlobalRdrEnv rdr_env new_gre)
328 new_gre = GRE {gre_name = name, gre_prov = LocalDef}
331 @getLocalDeclBinders@ returns the names for an @HsDecl@. It's
332 used for source code.
334 *** See "THE NAMING STORY" in HsDecls ****
337 getLocalDeclBinders :: TcGblEnv -> HsGroup RdrName -> RnM [Name]
338 getLocalDeclBinders gbl_env (HsGroup {hs_valds = ValBindsIn val_decls val_sigs,
339 hs_tyclds = tycl_decls,
340 hs_fords = foreign_decls })
341 = do { tc_names_s <- mappM new_tc tycl_decls
342 ; val_names <- mappM new_simple val_bndrs
343 ; return (foldr (++) val_names tc_names_s) }
345 mod = tcg_mod gbl_env
346 is_hs_boot = isHsBoot (tcg_src gbl_env) ;
347 val_bndrs | is_hs_boot = sig_hs_bndrs
348 | otherwise = for_hs_bndrs ++ val_hs_bndrs
349 -- In a hs-boot file, the value binders come from the
350 -- *signatures*, and there should be no foreign binders
352 new_simple rdr_name = newTopSrcBinder mod Nothing rdr_name
354 sig_hs_bndrs = [nm | L _ (Sig nm _) <- val_sigs]
355 val_hs_bndrs = collectHsBindLocatedBinders val_decls
356 for_hs_bndrs = [nm | L _ (ForeignImport nm _ _ _) <- foreign_decls]
359 = do { main_name <- newTopSrcBinder mod Nothing main_rdr
360 ; sub_names <- mappM (newTopSrcBinder mod (Just main_name)) sub_rdrs
361 ; return (main_name : sub_names) }
363 (main_rdr : sub_rdrs) = tyClDeclNames (unLoc tc_decl)
367 %************************************************************************
369 \subsection{Filtering imports}
371 %************************************************************************
373 @filterImports@ takes the @ExportEnv@ telling what the imported module makes
374 available, and filters it through the import spec (if any).
377 filterImports :: ModIface
378 -> ImpDeclSpec -- The span for the entire import decl
379 -> Maybe (Bool, [Located (IE RdrName)]) -- Import spec; True => hiding
380 -> NameSet -- What's available
381 -> RnM (NameSet, -- What's imported (qualified or unqualified)
382 GlobalRdrEnv) -- Same again, but in GRE form
384 -- Complains if import spec mentions things that the module doesn't export
385 -- Warns/informs if import spec contains duplicates.
387 mkGenericRdrEnv decl_spec names
388 = mkGlobalRdrEnv [ GRE { gre_name = name, gre_prov = Imported [imp_spec] }
389 | name <- nameSetToList names ]
391 imp_spec = ImpSpec { is_decl = decl_spec, is_item = ImpAll }
393 filterImports iface decl_spec Nothing all_names
394 = returnM (all_names, mkGenericRdrEnv decl_spec all_names)
396 filterImports iface decl_spec (Just (want_hiding, import_items)) all_names
397 = mappM (addLocM get_item) import_items `thenM` \ gres_s ->
400 specified_names = mkNameSet (map gre_name gres)
402 if not want_hiding then
403 return (specified_names, mkGlobalRdrEnv gres)
406 keep n = not (n `elemNameSet` specified_names)
407 pruned_avails = filterNameSet keep all_names
409 return (pruned_avails, mkGenericRdrEnv decl_spec pruned_avails)
412 occ_env :: OccEnv Name -- Maps OccName to corresponding Name
413 occ_env = mkOccEnv [(nameOccName n, n) | n <- nameSetToList all_names]
414 -- This env will have entries for data constructors too,
415 -- they won't make any difference because naked entities like T
416 -- in an import list map to TcOccs, not VarOccs.
418 sub_env :: NameEnv [Name]
419 sub_env = mkSubNameEnv all_names
421 bale_out item = addErr (badImportItemErr iface decl_spec item) `thenM_`
424 succeed_with :: Bool -> [Name] -> RnM [GlobalRdrElt]
425 succeed_with all_explicit names
426 = do { loc <- getSrcSpanM
427 ; returnM (map (mk_gre loc) names) }
429 mk_gre loc name = GRE { gre_name = name,
430 gre_prov = Imported [imp_spec] }
432 imp_spec = ImpSpec { is_decl = decl_spec, is_item = item_spec }
433 item_spec = ImpSome { is_explicit = explicit, is_iloc = loc }
434 explicit = all_explicit || isNothing (nameParent_maybe name)
436 get_item :: IE RdrName -> RnM [GlobalRdrElt]
437 -- Empty result for a bad item.
438 -- Singleton result is typical case.
439 -- Can have two when we are hiding, and mention C which might be
440 -- both a class and a data constructor.
441 get_item item@(IEModuleContents _)
444 get_item item@(IEThingAll tc)
445 = case check_item item of
448 [n] -> -- This occurs when you import T(..), but
449 -- only export T abstractly. The single [n]
450 -- in the AvailTC is the type or class itself
451 ifOptM Opt_WarnDodgyImports (addWarn (dodgyImportWarn tc)) `thenM_`
452 succeed_with False [n]
454 names -> succeed_with False names
456 get_item item@(IEThingAbs n)
457 | want_hiding -- hiding( C )
458 -- Here the 'C' can be a data constructor
459 -- *or* a type/class, or even both
460 = case concat [check_item item, check_item (IEVar data_n)] of
462 names -> succeed_with True names
464 data_n = setRdrNameSpace n srcDataName
467 = case check_item item of
469 names -> succeed_with True names
471 check_item :: IE RdrName -> [Name]
473 = case lookupOccEnv occ_env (rdrNameOcc (ieName item)) of
475 Just name -> filterAvail item name sub_env
479 %************************************************************************
481 \subsection{Export list processing}
483 %************************************************************************
485 Processing the export list.
487 You might think that we should record things that appear in the export
488 list as ``occurrences'' (using @addOccurrenceName@), but you'd be
489 wrong. We do check (here) that they are in scope, but there is no
490 need to slurp in their actual declaration (which is what
491 @addOccurrenceName@ forces).
493 Indeed, doing so would big trouble when compiling @PrelBase@, because
494 it re-exports @GHC@, which includes @takeMVar#@, whose type includes
495 @ConcBase.StateAndSynchVar#@, and so on...
498 type ExportAccum -- The type of the accumulating parameter of
499 -- the main worker function in rnExports
500 = ([Module], -- 'module M's seen so far
501 ExportOccMap, -- Tracks exported occurrence names
502 NameSet) -- The accumulated exported stuff
503 emptyExportAccum = ([], emptyOccEnv, emptyNameSet)
505 type ExportOccMap = OccEnv (Name, IE RdrName)
506 -- Tracks what a particular exported OccName
507 -- in an export list refers to, and which item
508 -- it came from. It's illegal to export two distinct things
509 -- that have the same occurrence name
512 rnExports :: Bool -- False => no 'module M(..) where' header at all
513 -> Maybe [Located (IE RdrName)] -- Nothing => no explicit export list
515 -- Complains if two distinct exports have same OccName
516 -- Warns about identical exports.
517 -- Complains about exports items not in scope
519 rnExports explicit_mod exports
520 = do { TcGblEnv { tcg_rdr_env = rdr_env,
521 tcg_imports = imports } <- getGblEnv ;
523 -- If the module header is omitted altogether, then behave
524 -- as if the user had written "module Main(main) where..."
525 -- EXCEPT in interactive mode, when we behave as if he had
526 -- written "module Main where ..."
527 -- Reason: don't want to complain about 'main' not in scope
528 -- in interactive mode
529 ghci_mode <- getGhciMode ;
531 | explicit_mod = exports
532 | ghci_mode == Interactive = Nothing
533 | otherwise = Just [noLoc (IEVar main_RDR_Unqual)] } ;
534 -- ToDo: the 'noLoc' here is unhelpful if 'main' turns out to be out of scope
535 exports_from_avail real_exports rdr_env imports }
538 exports_from_avail Nothing rdr_env imports
539 = -- Export all locally-defined things
540 -- We do this by filtering the global RdrEnv,
541 -- keeping only things that are locally-defined
542 return (mkNameSet [ gre_name gre
543 | gre <- globalRdrEnvElts rdr_env,
546 exports_from_avail (Just items) rdr_env (ImportAvails { imp_env = imp_env })
547 = foldlM do_litem emptyExportAccum items `thenM` \ (_, _, exports) ->
550 sub_env :: NameEnv [Name] -- Classify each name by its parent
551 sub_env = mkSubNameEnv (foldModuleEnv unionNameSets emptyNameSet imp_env)
553 do_litem :: ExportAccum -> Located (IE RdrName) -> RnM ExportAccum
554 do_litem acc = addLocM (exports_from_item acc)
556 exports_from_item :: ExportAccum -> IE RdrName -> RnM ExportAccum
557 exports_from_item acc@(mods, occs, exports) ie@(IEModuleContents mod)
558 | mod `elem` mods -- Duplicate export of M
559 = do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
560 warnIf warn_dup_exports (dupModuleExport mod) ;
564 = case lookupModuleEnv imp_env mod of
565 Nothing -> addErr (modExportErr mod) `thenM_`
569 new_exports = filterNameSet (inScopeUnqual rdr_env) names
572 -- This check_occs not only finds conflicts between this item
573 -- and others, but also internally within this item. That is,
574 -- if 'M.x' is in scope in several ways, we'll have several
575 -- members of mod_avails with the same OccName.
576 check_occs ie occs (nameSetToList new_exports) `thenM` \ occs' ->
577 returnM (mod:mods, occs', exports `unionNameSets` new_exports)
579 exports_from_item acc@(mods, occs, exports) ie
580 = lookupGlobalOccRn (ieName ie) `thenM` \ name ->
581 if isUnboundName name then
582 returnM acc -- Avoid error cascade
584 new_exports = filterAvail ie name sub_env
586 checkErr (not (null new_exports)) (exportItemErr ie) `thenM_`
587 checkForDodgyExport ie new_exports `thenM_`
588 check_occs ie occs new_exports `thenM` \ occs' ->
589 returnM (mods, occs', addListToNameSet exports new_exports)
591 -------------------------------
592 filterAvail :: IE RdrName -- Wanted
593 -> Name -- The Name of the ieName of the item
594 -> NameEnv [Name] -- Maps type/class names to their sub-names
595 -> [Name] -- Empty if even one thing reqd is missing
597 filterAvail (IEVar _) n subs = [n]
598 filterAvail (IEThingAbs _) n subs = [n]
599 filterAvail (IEThingAll _) n subs = n : subNames subs n
600 filterAvail (IEThingWith _ rdrs) n subs
601 | any isNothing mb_names = []
602 | otherwise = n : catMaybes mb_names
604 env = mkOccEnv [(nameOccName s, s) | s <- subNames subs n]
605 mb_names = map (lookupOccEnv env . rdrNameOcc) rdrs
606 filterAvail (IEModuleContents _) _ _ = panic "filterAvail"
608 subNames :: NameEnv [Name] -> Name -> [Name]
609 subNames env n = lookupNameEnv env n `orElse` []
611 mkSubNameEnv :: NameSet -> NameEnv [Name]
612 -- Maps types and classes to their constructors/classops respectively
613 -- This mapping just makes it easier to deal with A(..) export items
615 = foldNameSet add_name emptyNameEnv names
618 | Just parent <- nameParent_maybe name
619 = extendNameEnv_C (\ns _ -> name:ns) env parent [name]
622 -------------------------------
623 inScopeUnqual :: GlobalRdrEnv -> Name -> Bool
624 -- Checks whether the Name is in scope unqualified,
625 -- regardless of whether it's ambiguous or not
626 inScopeUnqual env n = any unQualOK (lookupGRE_Name env n)
628 -------------------------------
629 checkForDodgyExport :: IE RdrName -> [Name] -> RnM ()
630 checkForDodgyExport ie@(IEThingAll tc) [n]
631 | isTcOcc (nameOccName n) = addWarn (dodgyExportWarn tc)
632 -- This occurs when you export T(..), but
633 -- only import T abstractly, or T is a synonym.
634 -- The single [n] is the type or class itself
635 | otherwise = addErr (exportItemErr ie)
636 -- This happes if you export x(..), which is bogus
637 checkForDodgyExport _ _ = return ()
639 -------------------------------
640 check_occs :: IE RdrName -> ExportOccMap -> [Name] -> RnM ExportOccMap
641 check_occs ie occs names
642 = foldlM check occs names
645 = case lookupOccEnv occs name_occ of
646 Nothing -> returnM (extendOccEnv occs name_occ (name, ie))
649 | name == name' -- Duplicate export
650 -> do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
651 warnIf warn_dup_exports (dupExportWarn name_occ ie ie') ;
654 | otherwise -- Same occ name but different names: an error
655 -> do { global_env <- getGlobalRdrEnv ;
656 addErr (exportClashErr global_env name name' ie ie') ;
659 name_occ = nameOccName name
662 %*********************************************************
666 %*********************************************************
669 reportDeprecations :: TcGblEnv -> RnM ()
670 reportDeprecations tcg_env
671 = ifOptM Opt_WarnDeprecations $
672 do { (eps,hpt) <- getEpsAndHpt
673 -- By this time, typechecking is complete,
674 -- so the PIT is fully populated
675 ; mapM_ (check hpt (eps_PIT eps)) all_gres }
677 used_names = allUses (tcg_dus tcg_env)
678 -- Report on all deprecated uses; hence allUses
679 all_gres = globalRdrEnvElts (tcg_rdr_env tcg_env)
681 check hpt pit (GRE {gre_name = name, gre_prov = Imported (imp_spec:_)})
682 | name `elemNameSet` used_names
683 , Just deprec_txt <- lookupDeprec hpt pit name
684 = setSrcSpan (importSpecLoc imp_spec) $
685 addWarn (sep [ptext SLIT("Deprecated use of") <+>
686 occNameFlavour (nameOccName name) <+>
688 (parens imp_msg) <> colon,
691 name_mod = nameModule name
692 imp_mod = importSpecModule imp_spec
693 imp_msg = ptext SLIT("imported from") <+> ppr imp_mod <> extra
694 extra | imp_mod == name_mod = empty
695 | otherwise = ptext SLIT(", but defined in") <+> ppr name_mod
697 check hpt pit ok_gre = returnM () -- Local, or not used, or not deprectated
698 -- The Imported pattern-match: don't deprecate locally defined names
699 -- For a start, we may be exporting a deprecated thing
700 -- Also we may use a deprecated thing in the defn of another
701 -- deprecated things. We may even use a deprecated thing in
702 -- the defn of a non-deprecated thing, when changing a module's
705 lookupDeprec :: HomePackageTable -> PackageIfaceTable
706 -> Name -> Maybe DeprecTxt
707 lookupDeprec hpt pit n
708 = case lookupIface hpt pit (nameModule n) of
709 Just iface -> mi_dep_fn iface n `seqMaybe` -- Bleat if the thing, *or
710 mi_dep_fn iface (nameParent n) -- its parent*, is deprec'd
712 | isWiredInName n -> Nothing
713 -- We have not necessarily loaded the .hi file for a
714 -- wired-in name (yet), although we *could*.
715 -- And we never deprecate them
717 | otherwise -> pprPanic "lookupDeprec" (ppr n)
718 -- By now all the interfaces should have been loaded
720 gre_is_used :: NameSet -> GlobalRdrElt -> Bool
721 gre_is_used used_names gre = gre_name gre `elemNameSet` used_names
724 %*********************************************************
728 %*********************************************************
731 reportUnusedNames :: Maybe [Located (IE RdrName)] -- Export list
732 -> TcGblEnv -> RnM ()
733 reportUnusedNames export_decls gbl_env
734 = do { traceRn ((text "RUN") <+> (ppr (tcg_dus gbl_env)))
735 ; warnUnusedTopBinds unused_locals
736 ; warnUnusedModules unused_imp_mods
737 ; warnUnusedImports unused_imports
738 ; warnDuplicateImports defined_and_used
739 ; printMinimalImports minimal_imports }
741 used_names, all_used_names :: NameSet
742 used_names = findUses (tcg_dus gbl_env) emptyNameSet
743 -- NB: currently, if f x = g, we only treat 'g' as used if 'f' is used
746 all_used_names = used_names `unionNameSets`
747 mkNameSet (mapCatMaybes nameParent_maybe (nameSetToList used_names))
748 -- A use of C implies a use of T,
749 -- if C was brought into scope by T(..) or T(C)
751 -- Collect the defined names from the in-scope environment
752 defined_names :: [GlobalRdrElt]
753 defined_names = globalRdrEnvElts (tcg_rdr_env gbl_env)
755 -- Note that defined_and_used, defined_but_not_used
756 -- are both [GRE]; that's why we need defined_and_used
757 -- rather than just all_used_names
758 defined_and_used, defined_but_not_used :: [GlobalRdrElt]
759 (defined_and_used, defined_but_not_used)
760 = partition (gre_is_used all_used_names) defined_names
762 -- Filter out the ones that are
763 -- (a) defined in this module, and
764 -- (b) not defined by a 'deriving' clause
765 -- The latter have an Internal Name, so we can filter them out easily
766 unused_locals :: [GlobalRdrElt]
767 unused_locals = filter is_unused_local defined_but_not_used
768 is_unused_local :: GlobalRdrElt -> Bool
769 is_unused_local gre = isLocalGRE gre && isExternalName (gre_name gre)
771 unused_imports :: [GlobalRdrElt]
772 unused_imports = filter unused_imp defined_but_not_used
773 unused_imp (GRE {gre_prov = Imported imp_specs})
774 = not (all (module_unused . importSpecModule) imp_specs)
775 && or [exp | ImpSpec { is_item = ImpSome { is_explicit = exp } } <- imp_specs]
776 -- Don't complain about unused imports if we've already said the
777 -- entire import is unused
778 unused_imp other = False
780 -- To figure out the minimal set of imports, start with the things
781 -- that are in scope (i.e. in gbl_env). Then just combine them
782 -- into a bunch of avails, so they are properly grouped
784 -- BUG WARNING: this does not deal properly with qualified imports!
785 minimal_imports :: FiniteMap Module AvailEnv
786 minimal_imports0 = foldr add_expall emptyFM expall_mods
787 minimal_imports1 = foldr add_name minimal_imports0 defined_and_used
788 minimal_imports = foldr add_inst_mod minimal_imports1 direct_import_mods
789 -- The last line makes sure that we retain all direct imports
790 -- even if we import nothing explicitly.
791 -- It's not necessarily redundant to import such modules. Consider
795 -- The import M() is not *necessarily* redundant, even if
796 -- we suck in no instance decls from M (e.g. it contains
797 -- no instance decls, or This contains no code). It may be
798 -- that we import M solely to ensure that M's orphan instance
799 -- decls (or those in its imports) are visible to people who
800 -- import This. Sigh.
801 -- There's really no good way to detect this, so the error message
802 -- in RnEnv.warnUnusedModules is weakened instead
804 -- We've carefully preserved the provenance so that we can
805 -- construct minimal imports that import the name by (one of)
806 -- the same route(s) as the programmer originally did.
807 add_name (GRE {gre_name = n, gre_prov = Imported imp_specs}) acc
808 = addToFM_C plusAvailEnv acc (importSpecModule (head imp_specs))
809 (unitAvailEnv (mk_avail n (nameParent_maybe n)))
813 -- Modules mentioned as 'module M' in the export list
814 expall_mods = case export_decls of
816 Just es -> [m | L _ (IEModuleContents m) <- es]
818 -- This is really bogus. The idea is that if we see 'module M' in
819 -- the export list we must retain the import decls that drive it
820 -- If we aren't careful we might see
821 -- module A( module M ) where
824 -- and suppose that N exports everything that M does. Then we
825 -- must not drop the import of M even though N brings it all into
828 -- BUG WARNING: 'module M' exports aside, what if M.x is mentioned?!
830 -- The reason that add_expall is bogus is that it doesn't take
831 -- qualified imports into account. But it's an improvement.
832 add_expall mod acc = addToFM_C plusAvailEnv acc mod emptyAvailEnv
834 -- n is the name of the thing, p is the name of its parent
835 mk_avail n (Just p) = AvailTC p [p,n]
836 mk_avail n Nothing | isTcOcc (nameOccName n) = AvailTC n [n]
837 | otherwise = Avail n
839 add_inst_mod (mod,_,_) acc
840 | mod `elemFM` acc = acc -- We import something already
841 | otherwise = addToFM acc mod emptyAvailEnv
843 -- Add an empty collection of imports for a module
844 -- from which we have sucked only instance decls
846 imports = tcg_imports gbl_env
848 direct_import_mods :: [(Module, Bool, SrcSpan)]
849 -- See the type of the imp_mods for this triple
850 direct_import_mods = moduleEnvElts (imp_mods imports)
852 -- unused_imp_mods are the directly-imported modules
853 -- that are not mentioned in minimal_imports1
854 -- [Note: not 'minimal_imports', because that includes directly-imported
855 -- modules even if we use nothing from them; see notes above]
857 -- BUG WARNING: does not deal correctly with multiple imports of the same module
858 -- becuase direct_import_mods has only one entry per module
859 unused_imp_mods = [(mod,loc) | (mod,no_imp,loc) <- direct_import_mods,
860 not (mod `elemFM` minimal_imports1),
863 -- The not no_imp part is not to complain about
864 -- import M (), which is an idiom for importing
865 -- instance declarations
867 module_unused :: Module -> Bool
868 module_unused mod = any (((==) mod) . fst) unused_imp_mods
870 ---------------------
871 warnDuplicateImports :: [GlobalRdrElt] -> RnM ()
872 -- Given the GREs for names that are used, figure out which imports
873 -- could be omitted without changing the top-level environment.
875 -- NB: Given import Foo( T )
876 -- import qualified Foo
877 -- we do not report a duplicate import, even though Foo.T is brought
878 -- into scope by both, because there's nothing you can *omit* without
879 -- changing the top-level environment. So we complain only if it's
880 -- explicitly named in both imports or neither.
882 -- Furthermore, we complain about Foo.T only if
883 -- there is no complaint about (unqualified) T
885 warnDuplicateImports gres
886 = ifOptM Opt_WarnUnusedImports $
887 sequenceM_ [ warn name pr
888 -- The 'head' picks the first offending group
889 -- for this particular name
890 | GRE { gre_name = name, gre_prov = Imported imps } <- gres
891 , pr <- redundants imps ]
893 warn name (red_imp, cov_imp)
894 = addWarnAt (importSpecLoc red_imp)
895 (vcat [ptext SLIT("Redundant import of:") <+> quotes pp_name,
896 ptext SLIT("It is also") <+> ppr cov_imp])
898 pp_name | is_qual red_decl = ppr (is_as red_decl) <> dot <> ppr occ
899 | otherwise = ppr occ
900 occ = nameOccName name
901 red_decl = is_decl red_imp
903 redundants :: [ImportSpec] -> [(ImportSpec,ImportSpec)]
904 -- The returned pair is (redundant-import, covering-import)
906 = [ (red_imp, cov_imp)
908 , cov_imp <- take 1 (filter (covers red_imp) imps) ]
910 -- "red_imp" is a putative redundant import
911 -- "cov_imp" potentially covers it
912 -- This test decides whether red_imp could be dropped
914 -- NOTE: currently the test does not warn about
917 -- even if the same underlying 'x' is involved, because dropping
918 -- either import would change the qualified names in scope (M.x, N.x)
919 -- But if the qualified names aren't used, the import is indeed redundant
920 -- Sadly we don't know that. Oh well.
921 covers red_imp@(ImpSpec { is_decl = red_decl, is_item = red_item })
922 cov_imp@(ImpSpec { is_decl = cov_decl, is_item = cov_item })
924 = False -- Ignore diagonal elements
925 | not (is_as red_decl == is_as cov_decl)
926 = False -- They bring into scope different qualified names
927 | not (is_qual red_decl) && is_qual cov_decl
928 = False -- Covering one doesn't bring unqualified name into scope
930 = not cov_selective -- Redundant one is selective and covering one isn't
931 || red_later -- Both are explicit; tie-break using red_later
933 = not cov_selective -- Neither import is selective
934 && (is_mod red_decl == is_mod cov_decl) -- They import the same module
935 && red_later -- Tie-break
937 red_loc = importSpecLoc red_imp
938 cov_loc = importSpecLoc cov_imp
939 red_later = red_loc > cov_loc
940 cov_selective = selectiveImpItem cov_item
941 red_selective = selectiveImpItem red_item
943 selectiveImpItem :: ImpItemSpec -> Bool
944 selectiveImpItem ImpAll = False
945 selectiveImpItem (ImpSome {}) = True
947 -- ToDo: deal with original imports with 'qualified' and 'as M' clauses
948 printMinimalImports :: FiniteMap Module AvailEnv -- Minimal imports
950 printMinimalImports imps
951 = ifOptM Opt_D_dump_minimal_imports $ do {
953 mod_ies <- mappM to_ies (fmToList imps) ;
954 this_mod <- getModule ;
955 rdr_env <- getGlobalRdrEnv ;
956 ioToTcRn (do { h <- openFile (mkFilename this_mod) WriteMode ;
957 printForUser h (unQualInScope rdr_env)
958 (vcat (map ppr_mod_ie mod_ies)) })
961 mkFilename this_mod = moduleUserString this_mod ++ ".imports"
962 ppr_mod_ie (mod_name, ies)
963 | mod_name == pRELUDE
965 | null ies -- Nothing except instances comes from here
966 = ptext SLIT("import") <+> ppr mod_name <> ptext SLIT("() -- Instances only")
968 = ptext SLIT("import") <+> ppr mod_name <>
969 parens (fsep (punctuate comma (map ppr ies)))
971 to_ies (mod, avail_env) = mappM to_ie (availEnvElts avail_env) `thenM` \ ies ->
974 to_ie :: AvailInfo -> RnM (IE Name)
975 -- The main trick here is that if we're importing all the constructors
976 -- we want to say "T(..)", but if we're importing only a subset we want
977 -- to say "T(A,B,C)". So we have to find out what the module exports.
978 to_ie (Avail n) = returnM (IEVar n)
979 to_ie (AvailTC n [m]) = ASSERT( n==m )
980 returnM (IEThingAbs n)
982 = loadSrcInterface doc n_mod False `thenM` \ iface ->
983 case [xs | (m,as) <- mi_exports iface,
986 x == nameOccName n] of
987 [xs] | all_used xs -> returnM (IEThingAll n)
988 | otherwise -> returnM (IEThingWith n (filter (/= n) ns))
989 other -> pprTrace "to_ie" (ppr n <+> ppr n_mod <+> ppr other) $
992 all_used avail_occs = all (`elem` map nameOccName ns) avail_occs
993 doc = text "Compute minimal imports from" <+> ppr n
998 %************************************************************************
1002 %************************************************************************
1005 badImportItemErr iface decl_spec ie
1006 = sep [ptext SLIT("Module"), quotes (ppr (is_mod decl_spec)), source_import,
1007 ptext SLIT("does not export"), quotes (ppr ie)]
1009 source_import | mi_boot iface = ptext SLIT("(hi-boot interface)")
1012 dodgyImportWarn item = dodgyMsg (ptext SLIT("import")) item
1013 dodgyExportWarn item = dodgyMsg (ptext SLIT("export")) item
1016 = sep [ ptext SLIT("The") <+> kind <+> ptext SLIT("item") <+> quotes (ppr (IEThingAll tc)),
1017 ptext SLIT("suggests that") <+> quotes (ppr tc) <+> ptext SLIT("has constructor or class methods"),
1018 ptext SLIT("but it has none; it is a type synonym or abstract type or class") ]
1021 = hsep [ ptext SLIT("Unknown module in export list: module"), quotes (ppr mod)]
1023 exportItemErr export_item
1024 = sep [ ptext SLIT("The export item") <+> quotes (ppr export_item),
1025 ptext SLIT("attempts to export constructors or class methods that are not visible here") ]
1027 exportClashErr global_env name1 name2 ie1 ie2
1028 = vcat [ ptext SLIT("Conflicting exports for") <+> quotes (ppr occ) <> colon
1029 , ppr_export ie1 name1
1030 , ppr_export ie2 name2 ]
1032 occ = nameOccName name1
1033 ppr_export ie name = nest 2 (quotes (ppr ie) <+> ptext SLIT("exports") <+>
1034 quotes (ppr name) <+> pprNameProvenance (get_gre name))
1036 -- get_gre finds a GRE for the Name, so that we can show its provenance
1038 = case lookupGRE_Name global_env name of
1040 [] -> pprPanic "exportClashErr" (ppr name)
1042 addDupDeclErr :: Name -> Name -> TcRn ()
1043 addDupDeclErr name_a name_b
1044 = addErrAt (srcLocSpan loc2) $
1045 vcat [ptext SLIT("Multiple declarations of") <+> quotes (ppr name1),
1046 ptext SLIT("Declared at:") <+> vcat [ppr (nameSrcLoc name1), ppr loc2]]
1048 loc2 = nameSrcLoc name2
1049 (name1,name2) | nameSrcLoc name_a > nameSrcLoc name_b = (name_b,name_a)
1050 | otherwise = (name_a,name_b)
1051 -- Report the error at the later location
1053 dupExportWarn occ_name ie1 ie2
1054 = hsep [quotes (ppr occ_name),
1055 ptext SLIT("is exported by"), quotes (ppr ie1),
1056 ptext SLIT("and"), quotes (ppr ie2)]
1059 = hsep [ptext SLIT("Duplicate"),
1060 quotes (ptext SLIT("Module") <+> ppr mod),
1061 ptext SLIT("in export list")]
1063 moduleDeprec mod txt
1064 = sep [ ptext SLIT("Module") <+> quotes (ppr mod) <+> ptext SLIT("is deprecated:"),