2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[RnNames]{Extracting imported and top-level names in scope}
8 rnImports, mkRdrEnvAndImports, importsFromLocalDecls,
9 rnExports, mkExportNameSet,
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 IfaceEnv ( ifaceExportNames )
24 import LoadIface ( loadSrcInterface )
25 import TcRnMonad hiding (LIE)
30 import Name ( Name, nameSrcLoc, nameOccName, nameModule, isWiredInName,
31 nameParent, nameParent_maybe, isExternalName,
32 isBuiltInSyntax, isTyConName )
35 import OccName ( srcDataName, isTcOcc, pprNonVarNameSpace,
37 OccEnv, mkOccEnv, lookupOccEnv, emptyOccEnv,
39 import HscTypes ( GenAvailInfo(..), AvailInfo,
40 HomePackageTable, PackageIfaceTable,
42 Deprecs(..), ModIface(..), Dependencies(..),
43 lookupIfaceByModule, ExternalPackageState(..)
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 )
53 import Maybes ( isNothing, catMaybes, mapCatMaybes, seqMaybe, orElse )
54 import SrcLoc ( Located(..), mkGeneralSrcSpan,
55 unLoc, noLoc, srcLocSpan, SrcSpan )
56 import BasicTypes ( DeprecTxt )
57 import DriverPhases ( isHsBoot )
58 import Util ( notNull )
59 import List ( partition )
60 import IO ( openFile, IOMode(..) )
61 import Monad ( liftM, when )
66 %************************************************************************
70 %************************************************************************
73 rnImports :: [LImportDecl RdrName] -> RnM [LImportDecl Name]
75 -- PROCESS IMPORT DECLS
76 -- Do the non {- SOURCE -} ones first, so that we get a helpful
77 -- warning for {- SOURCE -} ones that are unnecessary
78 = do this_mod <- getModule
79 implicit_prelude <- doptM Opt_ImplicitPrelude
80 let all_imports = mk_prel_imports this_mod implicit_prelude ++ imports
81 (source, ordinary) = partition is_source_import all_imports
82 is_source_import (L _ (ImportDecl _ is_boot _ _ _)) = is_boot
83 get_imports = rnImportDecl this_mod
85 stuff1 <- mapM get_imports ordinary
86 stuff2 <- mapM get_imports source
87 return (stuff1 ++ stuff2)
89 -- NB: opt_NoImplicitPrelude is slightly different to import Prelude ();
90 -- because the former doesn't even look at Prelude.hi for instance
91 -- declarations, whereas the latter does.
92 mk_prel_imports this_mod implicit_prelude
94 || explicit_prelude_import
95 || not implicit_prelude
97 | otherwise = [preludeImportDecl]
98 explicit_prelude_import
99 = notNull [ () | L _ (ImportDecl mod _ _ _ _) <- imports,
100 unLoc mod == pRELUDE_NAME ]
102 preludeImportDecl :: LImportDecl RdrName
105 ImportDecl (L loc pRELUDE_NAME)
106 False {- Not a boot interface -}
107 False {- Not qualified -}
108 Nothing {- No "as" -}
109 Nothing {- No import list -}
111 loc = mkGeneralSrcSpan FSLIT("Implicit import declaration")
113 mkRdrEnvAndImports :: [LImportDecl Name] -> RnM (GlobalRdrEnv, ImportAvails)
114 mkRdrEnvAndImports imports
115 = do this_mod <- getModule
116 let get_imports = importsFromImportDecl this_mod
117 stuff <- mapM get_imports imports
118 let (imp_gbl_envs, imp_avails) = unzip stuff
119 gbl_env :: GlobalRdrEnv
120 gbl_env = foldr plusGlobalRdrEnv emptyGlobalRdrEnv imp_gbl_envs
122 all_avails :: ImportAvails
123 all_avails = foldr plusImportAvails emptyImportAvails imp_avails
125 return (gbl_env, all_avails)
130 rnImportDecl :: Module
131 -> LImportDecl RdrName
132 -> RnM (LImportDecl Name)
133 rnImportDecl this_mod (L loc importDecl@(ImportDecl loc_imp_mod_name want_boot qual_only as_mod imp_details))
135 do iface <- loadSrcInterface doc imp_mod_name want_boot
136 let qual_mod_name = case as_mod of
137 Nothing -> imp_mod_name
138 Just another_name -> another_name
139 imp_spec = ImpDeclSpec { is_mod = imp_mod_name, is_qual = qual_only,
140 is_dloc = loc, is_as = qual_mod_name }
141 total_avails <- ifaceExportNames (mi_exports iface)
142 importDecl' <- rnImportDecl' iface imp_spec importDecl total_avails
143 return (L loc importDecl')
144 where imp_mod_name = unLoc loc_imp_mod_name
145 doc = ppr imp_mod_name <+> ptext SLIT("is directly imported")
147 rnImportDecl' :: ModIface -> ImpDeclSpec -> ImportDecl RdrName -> NameSet -> RnM (ImportDecl Name)
148 rnImportDecl' iface decl_spec (ImportDecl mod_name want_boot qual_only as_mod Nothing) all_names
149 = return $ ImportDecl mod_name want_boot qual_only as_mod Nothing
150 rnImportDecl' iface decl_spec (ImportDecl mod_name want_boot qual_only as_mod (Just (want_hiding,import_items))) all_names
151 = do import_items_mbs <- mapM (srcSpanWrapper) import_items
152 let rn_import_items = concat . catMaybes $ import_items_mbs
153 return $ ImportDecl mod_name want_boot qual_only as_mod (Just (want_hiding,rn_import_items))
155 srcSpanWrapper (L span ieRdr)
156 = case get_item ieRdr of
158 -> do addErrAt span (badImportItemErr iface decl_spec ieRdr)
161 -> return (Just [L span ie | ie <- ieNames])
162 occ_env :: OccEnv Name -- Maps OccName to corresponding Name
163 occ_env = mkOccEnv [(nameOccName n, n) | n <- nameSetToList all_names]
164 -- This env will have entries for data constructors too,
165 -- they won't make any difference because naked entities like T
166 -- in an import list map to TcOccs, not VarOccs.
168 sub_env :: NameEnv [Name]
169 sub_env = mkSubNameEnv all_names
171 get_item :: IE RdrName -> Maybe [IE Name]
172 -- Empty result for a bad item.
173 -- Singleton result is typical case.
174 -- Can have two when we are hiding, and mention C which might be
175 -- both a class and a data constructor.
176 get_item item@(IEModuleContents _)
178 get_item (IEThingAll tc)
179 = do name <- check_name tc
180 return [IEThingAll name]
181 get_item (IEThingAbs tc)
182 | want_hiding -- hiding ( C )
183 -- Here the 'C' can be a data constructor
184 -- *or* a type/class, or even both
185 = case catMaybes [check_name tc, check_name (setRdrNameSpace tc srcDataName)] of
187 names -> return [ IEThingAbs n | n <- names ]
189 = do name <- check_name tc
190 return [IEThingAbs name]
191 get_item (IEThingWith n ns) -- import (C (A,B))
192 = do name <- check_name n
193 let env = mkOccEnv [(nameOccName s, s) | s <- subNames sub_env name]
194 mb_names = map (lookupOccEnv env . rdrNameOcc) ns
195 names <- sequence mb_names
196 return [IEThingWith name names]
198 = do name <- check_name n
201 check_name :: RdrName -> Maybe Name
203 = lookupOccEnv occ_env (rdrNameOcc rdrName)
206 importsFromImportDecl :: Module
208 -> RnM (GlobalRdrEnv, ImportAvails)
210 importsFromImportDecl this_mod
211 (L loc (ImportDecl loc_imp_mod_name want_boot qual_only as_mod imp_details))
215 -- If there's an error in loadInterface, (e.g. interface
216 -- file not found) we get lots of spurious errors from 'filterImports'
218 imp_mod_name = unLoc loc_imp_mod_name
219 doc = ppr imp_mod_name <+> ptext SLIT("is directly imported")
221 loadSrcInterface doc imp_mod_name want_boot `thenM` \ iface ->
223 -- Compiler sanity check: if the import didn't say
224 -- {-# SOURCE #-} we should not get a hi-boot file
225 WARN( not want_boot && mi_boot iface, ppr imp_mod_name )
227 -- Issue a user warning for a redundant {- SOURCE -} import
228 -- NB that we arrange to read all the ordinary imports before
229 -- any of the {- SOURCE -} imports
230 warnIf (want_boot && not (mi_boot iface))
231 (warnRedundantSourceImport imp_mod_name) `thenM_`
234 imp_mod = mi_module iface
235 deprecs = mi_deprecs iface
236 is_orph = mi_orphan iface
239 filtered_exports = filter not_this_mod (mi_exports iface)
240 not_this_mod (mod,_) = mod /= this_mod
241 -- If the module exports anything defined in this module, just ignore it.
242 -- Reason: otherwise it looks as if there are two local definition sites
243 -- for the thing, and an error gets reported. Easiest thing is just to
244 -- filter them out up front. This situation only arises if a module
245 -- imports itself, or another module that imported it. (Necessarily,
246 -- this invoves a loop.)
248 -- Tiresome consequence: if you say
253 -- module B( AType ) where
254 -- import {-# SOURCE #-} A( AType )
256 -- then you'll get a 'B does not export AType' message. Oh well.
258 qual_mod_name = case as_mod of
259 Nothing -> imp_mod_name
260 Just another_name -> another_name
261 imp_spec = ImpDeclSpec { is_mod = imp_mod_name, is_qual = qual_only,
262 is_dloc = loc, is_as = qual_mod_name }
264 -- Get the total imports, and filter them according to the import list
265 ifaceExportNames filtered_exports `thenM` \ total_avails ->
266 filterImports iface imp_spec
267 imp_details total_avails `thenM` \ (avail_env, gbl_env) ->
269 getDOpts `thenM` \ dflags ->
272 -- Compute new transitive dependencies
274 orphans | is_orph = ASSERT( not (imp_mod `elem` dep_orphs deps) )
275 imp_mod : dep_orphs deps
276 | otherwise = dep_orphs deps
278 pkg = modulePackageId (mi_module iface)
280 (dependent_mods, dependent_pkgs)
281 | pkg == thisPackage dflags =
282 -- Imported module is from the home package
283 -- Take its dependent modules and add imp_mod itself
284 -- Take its dependent packages unchanged
286 -- NB: (dep_mods deps) might include a hi-boot file
287 -- for the module being compiled, CM. Do *not* filter
288 -- this out (as we used to), because when we've
289 -- finished dealing with the direct imports we want to
290 -- know if any of them depended on CM.hi-boot, in
291 -- which case we should do the hi-boot consistency
292 -- check. See LoadIface.loadHiBootInterface
293 ((imp_mod_name, want_boot) : dep_mods deps, dep_pkgs deps)
296 -- Imported module is from another package
297 -- Dump the dependent modules
298 -- Add the package imp_mod comes from to the dependent packages
299 ASSERT2( not (pkg `elem` dep_pkgs deps), ppr pkg <+> ppr (dep_pkgs deps) )
300 ([], pkg : dep_pkgs deps)
302 -- True <=> import M ()
303 import_all = case imp_details of
304 Just (is_hiding, ls) -> not is_hiding && null ls
307 -- unqual_avails is the Avails that are visible in *unqualified* form
308 -- We need to know this so we know what to export when we see
309 -- module M ( module P ) where ...
310 -- Then we must export whatever came from P unqualified.
311 imports = ImportAvails {
312 imp_env = unitUFM qual_mod_name avail_env,
313 imp_mods = unitModuleEnv imp_mod (imp_mod, import_all, loc),
315 imp_dep_mods = mkModDeps dependent_mods,
316 imp_dep_pkgs = dependent_pkgs }
319 -- Complain if we import a deprecated module
320 ifOptM Opt_WarnDeprecations (
322 DeprecAll txt -> addWarn (moduleDeprec imp_mod_name txt)
326 returnM (gbl_env, imports)
328 warnRedundantSourceImport mod_name
329 = ptext SLIT("Unnecessary {-# SOURCE #-} in the import of module")
330 <+> quotes (ppr mod_name)
334 %************************************************************************
336 importsFromLocalDecls
338 %************************************************************************
340 From the top-level declarations of this module produce
341 * the lexical environment
343 created by its bindings.
345 Complain about duplicate bindings
348 importsFromLocalDecls :: HsGroup RdrName -> RnM TcGblEnv
349 importsFromLocalDecls group
350 = do { gbl_env <- getGblEnv
352 ; names <- getLocalDeclBinders gbl_env group
354 ; implicit_prelude <- doptM Opt_ImplicitPrelude
356 -- Optimisation: filter out names for built-in syntax
357 -- They just clutter up the environment (esp tuples), and the parser
358 -- will generate Exact RdrNames for them, so the cluttered
359 -- envt is no use. To avoid doing this filter all the time,
360 -- we use -fno-implicit-prelude as a clue that the filter is
361 -- worth while. Really, it's only useful for GHC.Base and GHC.Tuple.
363 -- It's worth doing because it makes the environment smaller for
364 -- every module that imports the Prelude
366 -- Note: don't filter the gbl_env (hence all_names, not filered_all_names
367 -- in defn of gres above). Stupid reason: when parsing
368 -- data type decls, the constructors start as Exact tycon-names,
369 -- and then get turned into data con names by zapping the name space;
370 -- but that stops them being Exact, so they get looked up.
371 -- Ditto in fixity decls; e.g. infix 5 :
372 -- Sigh. It doesn't matter because it only affects the Data.Tuple really.
373 -- The important thing is to trim down the exports.
375 | implicit_prelude = names
376 | otherwise = filter (not . isBuiltInSyntax) names ;
378 ; this_mod = tcg_mod gbl_env
379 ; imports = emptyImportAvails {
380 imp_env = unitUFM (moduleName this_mod) $
381 mkNameSet filtered_names
385 ; rdr_env' <- extendRdrEnvRn (tcg_rdr_env gbl_env) names
387 ; returnM (gbl_env { tcg_rdr_env = rdr_env',
388 tcg_imports = imports `plusImportAvails` tcg_imports gbl_env })
391 extendRdrEnvRn :: GlobalRdrEnv -> [Name] -> RnM GlobalRdrEnv
392 -- Add the new locally-bound names one by one, checking for duplicates as
393 -- we do so. Remember that in Template Haskell the duplicates
394 -- might *already be* in the GlobalRdrEnv from higher up the module
395 extendRdrEnvRn rdr_env names
396 = foldlM add_local rdr_env names
398 add_local rdr_env name
399 | gres <- lookupGlobalRdrEnv rdr_env (nameOccName name)
400 , (dup_gre:_) <- filter isLocalGRE gres -- Check for existing *local* defns
401 = do { addDupDeclErr (gre_name dup_gre) name
404 = return (extendGlobalRdrEnv rdr_env new_gre)
406 new_gre = GRE {gre_name = name, gre_prov = LocalDef}
409 @getLocalDeclBinders@ returns the names for an @HsDecl@. It's
410 used for source code.
412 *** See "THE NAMING STORY" in HsDecls ****
414 Instances of indexed types
415 ~~~~~~~~~~~~~~~~~~~~~~~~~~
416 Indexed data/newtype instances contain data constructors that we need to
417 collect, too. Moreover, we need to descend into the data/newtypes instances
418 of associated families.
420 We need to be careful with the handling of the type constructor of each type
421 instance as the family constructor is already defined, and we want to avoid
422 raising a duplicate declaration error. So, we make a new name for it, but
423 don't return it in the 'AvailInfo'.
426 getLocalDeclBinders :: TcGblEnv -> HsGroup RdrName -> RnM [Name]
427 getLocalDeclBinders gbl_env (HsGroup {hs_valds = ValBindsIn val_decls val_sigs,
428 hs_tyclds = tycl_decls,
429 hs_instds = inst_decls,
430 hs_fords = foreign_decls })
431 = do { tc_names_s <- mappM new_tc tycl_decls
432 ; at_names_s <- mappM inst_ats inst_decls
433 ; val_names <- mappM new_simple val_bndrs
434 ; return (foldr (++) val_names (tc_names_s ++ concat at_names_s)) }
436 mod = tcg_mod gbl_env
437 is_hs_boot = isHsBoot (tcg_src gbl_env) ;
438 val_bndrs | is_hs_boot = sig_hs_bndrs
439 | otherwise = for_hs_bndrs ++ val_hs_bndrs
440 -- In a hs-boot file, the value binders come from the
441 -- *signatures*, and there should be no foreign binders
443 new_simple rdr_name = newTopSrcBinder mod Nothing rdr_name
445 sig_hs_bndrs = [nm | L _ (TypeSig nm _) <- val_sigs]
446 val_hs_bndrs = collectHsBindLocatedBinders val_decls
447 for_hs_bndrs = [nm | L _ (ForeignImport nm _ _) <- foreign_decls]
450 = do { main_name <- newTopSrcBinder mod Nothing main_rdr
451 ; sub_names <- mappM (newTopSrcBinder mod (Just main_name)) sub_rdrs
452 ; if isIdxTyDecl (unLoc tc_decl) -- index type definitions
453 then return ( sub_names) -- are usage occurences
454 else return (main_name : sub_names) }
456 (main_rdr : sub_rdrs) = tyClDeclNames (unLoc tc_decl)
459 = mappM new_tc (instDeclATs (unLoc inst_decl))
463 %************************************************************************
465 \subsection{Filtering imports}
467 %************************************************************************
469 @filterImports@ takes the @ExportEnv@ telling what the imported module makes
470 available, and filters it through the import spec (if any).
473 filterImports :: ModIface
474 -> ImpDeclSpec -- The span for the entire import decl
475 -> Maybe (Bool, [LIE Name]) -- Import spec; True => hiding
476 -> NameSet -- What's available
477 -> RnM (NameSet, -- What's imported (qualified or unqualified)
478 GlobalRdrEnv) -- Same again, but in GRE form
480 -- Complains if import spec mentions things that the module doesn't export
481 -- Warns/informs if import spec contains duplicates.
483 mkGenericRdrEnv decl_spec names
484 = mkGlobalRdrEnv [ GRE { gre_name = name, gre_prov = Imported [imp_spec] }
485 | name <- nameSetToList names ]
487 imp_spec = ImpSpec { is_decl = decl_spec, is_item = ImpAll }
489 filterImports iface decl_spec Nothing all_names
490 = return (all_names, mkGenericRdrEnv decl_spec all_names)
492 filterImports iface decl_spec (Just (want_hiding, import_items)) all_names
493 = mapM (addLocM get_item) import_items >>= \gres_s ->
494 let gres = concat gres_s
495 specified_names = mkNameSet (map gre_name gres)
496 in if not want_hiding then
497 return (specified_names, mkGlobalRdrEnv gres)
498 else let keep n = not (n `elemNameSet` specified_names)
499 pruned_avails = filterNameSet keep all_names
500 in return (pruned_avails, mkGenericRdrEnv decl_spec pruned_avails)
502 sub_env :: NameEnv [Name] -- Classify each name by its parent
503 sub_env = mkSubNameEnv all_names
505 succeed_with :: Bool -> [Name] -> RnM [GlobalRdrElt]
506 succeed_with all_explicit names
507 = do { loc <- getSrcSpanM
508 ; returnM (map (mk_gre loc) names) }
510 mk_gre loc name = GRE { gre_name = name,
511 gre_prov = Imported [imp_spec] }
513 imp_spec = ImpSpec { is_decl = decl_spec, is_item = item_spec }
514 item_spec = ImpSome { is_explicit = explicit, is_iloc = loc }
515 explicit = all_explicit || isNothing (nameParent_maybe name)
517 get_item :: IE Name -> RnM [GlobalRdrElt]
518 -- Empty result for a bad item.
519 -- Singleton result is typical case.
520 -- Can have two when we are hiding, and mention C which might be
521 -- both a class and a data constructor.
522 get_item item@(IEModuleContents _)
523 -- This case should be filtered out by 'rnImports'.
524 = panic "filterImports: IEModuleContents?"
526 get_item (IEThingAll name)
527 = case subNames sub_env name of
528 [] -> -- This occurs when you import T(..), but
529 -- only export T abstractly.
530 do ifOptM Opt_WarnDodgyImports (addWarn (dodgyImportWarn name))
531 succeed_with False [name]
532 names -> succeed_with False (name:names)
534 get_item (IEThingAbs name)
535 = succeed_with True [name]
537 get_item (IEThingWith name names)
538 = do { optIdxTypes <- doptM Opt_IndexedTypes
539 ; when (not optIdxTypes && any isTyConName names) $
540 addErr (typeItemErr (head . filter isTyConName $ names )
541 (text "in import list"))
542 ; succeed_with True (name:names) }
543 get_item (IEVar name)
544 = succeed_with True [name]
549 %************************************************************************
551 \subsection{Export list processing}
553 %************************************************************************
555 Processing the export list.
557 You might think that we should record things that appear in the export
558 list as ``occurrences'' (using @addOccurrenceName@), but you'd be
559 wrong. We do check (here) that they are in scope, but there is no
560 need to slurp in their actual declaration (which is what
561 @addOccurrenceName@ forces).
563 Indeed, doing so would big trouble when compiling @PrelBase@, because
564 it re-exports @GHC@, which includes @takeMVar#@, whose type includes
565 @ConcBase.StateAndSynchVar#@, and so on...
568 type ExportAccum -- The type of the accumulating parameter of
569 -- the main worker function in rnExports
570 = ([ModuleName], -- 'module M's seen so far
571 ExportOccMap, -- Tracks exported occurrence names
572 NameSet) -- The accumulated exported stuff
573 emptyExportAccum = ([], emptyOccEnv, emptyNameSet)
575 type ExportOccMap = OccEnv (Name, IE RdrName)
576 -- Tracks what a particular exported OccName
577 -- in an export list refers to, and which item
578 -- it came from. It's illegal to export two distinct things
579 -- that have the same occurrence name
581 rnExports :: Maybe [LIE RdrName]
582 -> RnM (Maybe [LIE Name])
583 rnExports Nothing = return Nothing
584 rnExports (Just exports)
585 = do TcGblEnv { tcg_imports = ImportAvails { imp_env = imp_env } } <- getGblEnv
586 let sub_env :: NameEnv [Name] -- Classify each name by its parent
587 sub_env = mkSubNameEnv (foldUFM unionNameSets emptyNameSet imp_env)
588 rnExport (IEVar rdrName)
589 = do name <- lookupGlobalOccRn rdrName
591 rnExport (IEThingAbs rdrName)
592 = do name <- lookupGlobalOccRn rdrName
593 return (IEThingAbs name)
594 rnExport (IEThingAll rdrName)
595 = do name <- lookupGlobalOccRn rdrName
596 return (IEThingAll name)
597 rnExport ie@(IEThingWith rdrName rdrNames)
598 = do name <- lookupGlobalOccRn rdrName
599 if isUnboundName name
600 then return (IEThingWith name [])
602 let env = mkOccEnv [(nameOccName s, s) | s <- subNames sub_env name]
603 mb_names = map (lookupOccEnv env . rdrNameOcc) rdrNames
604 if any isNothing mb_names
605 then do addErr (exportItemErr ie)
606 return (IEThingWith name [])
607 else do let names = catMaybes mb_names
608 optIdxTypes <- doptM Opt_IndexedTypes
609 when (not optIdxTypes && any isTyConName names) $
610 addErr (typeItemErr ( head
613 (text "in export list"))
614 return (IEThingWith name names)
615 rnExport (IEModuleContents mod)
616 = return (IEModuleContents mod)
617 rn_exports <- mapM (wrapLocM rnExport) exports
618 return (Just rn_exports)
620 mkExportNameSet :: Bool -- False => no 'module M(..) where' header at all
621 -> Maybe ([LIE Name], [LIE RdrName]) -- Nothing => no explicit export list
623 -- Complains if two distinct exports have same OccName
624 -- Warns about identical exports.
625 -- Complains about exports items not in scope
627 mkExportNameSet explicit_mod exports
628 = do TcGblEnv { tcg_rdr_env = rdr_env,
629 tcg_imports = imports } <- getGblEnv
631 -- If the module header is omitted altogether, then behave
632 -- as if the user had written "module Main(main) where..."
633 -- EXCEPT in interactive mode, when we behave as if he had
634 -- written "module Main where ..."
635 -- Reason: don't want to complain about 'main' not in scope
636 -- in interactive mode
637 ghc_mode <- getGhcMode
638 real_exports <- case () of
641 | ghc_mode == Interactive
644 -> do mainName <- lookupGlobalOccRn main_RDR_Unqual
645 return (Just ([noLoc (IEVar mainName)]
646 ,[noLoc (IEVar main_RDR_Unqual)]))
647 -- ToDo: the 'noLoc' here is unhelpful if 'main' turns out to be out of scope
648 exports_from_avail real_exports rdr_env imports
651 exports_from_avail Nothing rdr_env imports
652 = -- Export all locally-defined things
653 -- We do this by filtering the global RdrEnv,
654 -- keeping only things that are locally-defined
655 return (mkNameSet [ gre_name gre
656 | gre <- globalRdrEnvElts rdr_env,
659 exports_from_avail (Just (items,origItems)) rdr_env (ImportAvails { imp_env = imp_env })
660 = do (_, _, exports) <- foldlM do_litem emptyExportAccum (zip items origItems)
663 sub_env :: NameEnv [Name] -- Classify each name by its parent
664 sub_env = mkSubNameEnv (foldUFM unionNameSets emptyNameSet imp_env)
666 do_litem :: ExportAccum -> (LIE Name, LIE RdrName) -> RnM ExportAccum
667 do_litem acc (ieName, ieRdr)
668 = addLocM (exports_from_item acc (unLoc ieRdr)) ieName
670 exports_from_item :: ExportAccum -> IE RdrName -> IE Name -> RnM ExportAccum
671 exports_from_item acc@(mods, occs, exports) ieRdr@(IEModuleContents mod) ie
672 | mod `elem` mods -- Duplicate export of M
673 = do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
674 warnIf warn_dup_exports (dupModuleExport mod) ;
678 = case lookupUFM imp_env mod of
679 Nothing -> do addErr (modExportErr mod)
682 -> do let new_exports = filterNameSet (inScopeUnqual rdr_env) names
683 -- This check_occs not only finds conflicts between this item
684 -- and others, but also internally within this item. That is,
685 -- if 'M.x' is in scope in several ways, we'll have several
686 -- members of mod_avails with the same OccName.
687 occs' <- check_occs ieRdr occs (nameSetToList new_exports)
688 return (mod:mods, occs', exports `unionNameSets` new_exports)
690 exports_from_item acc@(mods, occs, exports) ieRdr ie
691 = if isUnboundName (ieName ie)
692 then return acc -- Avoid error cascade
693 else let new_exports = filterAvail ie sub_env in
694 do -- checkErr (not (null (drop 1 new_exports))) (exportItemErr ie)
695 checkForDodgyExport ie new_exports
696 occs' <- check_occs ieRdr occs new_exports
697 return (mods, occs', addListToNameSet exports new_exports)
699 -------------------------------
700 filterAvail :: IE Name -- Wanted
701 -> NameEnv [Name] -- Maps type/class names to their sub-names
704 filterAvail (IEVar n) subs = [n]
705 filterAvail (IEThingAbs n) subs = [n]
706 filterAvail (IEThingAll n) subs = n : subNames subs n
707 filterAvail (IEThingWith n ns) subs = n : ns
708 filterAvail (IEModuleContents _) _ = panic "filterAvail"
710 subNames :: NameEnv [Name] -> Name -> [Name]
711 subNames env n = lookupNameEnv env n `orElse` []
713 mkSubNameEnv :: NameSet -> NameEnv [Name]
714 -- Maps types and classes to their constructors/classops respectively
715 -- This mapping just makes it easier to deal with A(..) export items
717 = foldNameSet add_name emptyNameEnv names
720 | Just parent <- nameParent_maybe name
721 = extendNameEnv_C (\ns _ -> name:ns) env parent [name]
724 -------------------------------
725 inScopeUnqual :: GlobalRdrEnv -> Name -> Bool
726 -- Checks whether the Name is in scope unqualified,
727 -- regardless of whether it's ambiguous or not
728 inScopeUnqual env n = any unQualOK (lookupGRE_Name env n)
730 -------------------------------
731 checkForDodgyExport :: IE Name -> [Name] -> RnM ()
732 checkForDodgyExport ie@(IEThingAll tc) [n]
733 | isTcOcc (nameOccName n) = addWarn (dodgyExportWarn tc)
734 -- This occurs when you export T(..), but
735 -- only import T abstractly, or T is a synonym.
736 -- The single [n] is the type or class itself
737 | otherwise = addErr (exportItemErr ie)
738 -- This happes if you export x(..), which is bogus
739 checkForDodgyExport _ _ = return ()
741 -------------------------------
742 check_occs :: IE RdrName -> ExportOccMap -> [Name] -> RnM ExportOccMap
743 check_occs ie occs names
744 = foldlM check occs names
747 = case lookupOccEnv occs name_occ of
748 Nothing -> returnM (extendOccEnv occs name_occ (name, ie))
751 | name == name' -- Duplicate export
752 -> do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
753 warnIf warn_dup_exports (dupExportWarn name_occ ie ie') ;
756 | otherwise -- Same occ name but different names: an error
757 -> do { global_env <- getGlobalRdrEnv ;
758 addErr (exportClashErr global_env name' name ie' ie) ;
761 name_occ = nameOccName name
764 %*********************************************************
768 %*********************************************************
771 reportDeprecations :: DynFlags -> TcGblEnv -> RnM ()
772 reportDeprecations dflags tcg_env
773 = ifOptM Opt_WarnDeprecations $
774 do { (eps,hpt) <- getEpsAndHpt
775 -- By this time, typechecking is complete,
776 -- so the PIT is fully populated
777 ; mapM_ (check hpt (eps_PIT eps)) all_gres }
779 used_names = allUses (tcg_dus tcg_env)
780 -- Report on all deprecated uses; hence allUses
781 all_gres = globalRdrEnvElts (tcg_rdr_env tcg_env)
783 check hpt pit (GRE {gre_name = name, gre_prov = Imported (imp_spec:_)})
784 | name `elemNameSet` used_names
785 , Just deprec_txt <- lookupDeprec dflags hpt pit name
786 = addWarnAt (importSpecLoc imp_spec)
787 (sep [ptext SLIT("Deprecated use of") <+>
788 pprNonVarNameSpace (occNameSpace (nameOccName name)) <+>
790 (parens imp_msg) <> colon,
793 name_mod = nameModule name
794 imp_mod = importSpecModule imp_spec
795 imp_msg = ptext SLIT("imported from") <+> ppr imp_mod <> extra
796 extra | imp_mod == moduleName name_mod = empty
797 | otherwise = ptext SLIT(", but defined in") <+> ppr name_mod
799 check hpt pit ok_gre = returnM () -- Local, or not used, or not deprectated
800 -- The Imported pattern-match: don't deprecate locally defined names
801 -- For a start, we may be exporting a deprecated thing
802 -- Also we may use a deprecated thing in the defn of another
803 -- deprecated things. We may even use a deprecated thing in
804 -- the defn of a non-deprecated thing, when changing a module's
807 lookupDeprec :: DynFlags -> HomePackageTable -> PackageIfaceTable
808 -> Name -> Maybe DeprecTxt
809 lookupDeprec dflags hpt pit n
810 = case lookupIfaceByModule dflags hpt pit (nameModule n) of
811 Just iface -> mi_dep_fn iface n `seqMaybe` -- Bleat if the thing, *or
812 mi_dep_fn iface (nameParent n) -- its parent*, is deprec'd
814 | isWiredInName n -> Nothing
815 -- We have not necessarily loaded the .hi file for a
816 -- wired-in name (yet), although we *could*.
817 -- And we never deprecate them
819 | otherwise -> pprPanic "lookupDeprec" (ppr n)
820 -- By now all the interfaces should have been loaded
822 gre_is_used :: NameSet -> GlobalRdrElt -> Bool
823 gre_is_used used_names gre = gre_name gre `elemNameSet` used_names
826 %*********************************************************
830 %*********************************************************
833 reportUnusedNames :: Maybe [LIE RdrName] -- Export list
834 -> TcGblEnv -> RnM ()
835 reportUnusedNames export_decls gbl_env
836 = do { traceRn ((text "RUN") <+> (ppr (tcg_dus gbl_env)))
837 ; warnUnusedTopBinds unused_locals
838 ; warnUnusedModules unused_imp_mods
839 ; warnUnusedImports unused_imports
840 ; warnDuplicateImports defined_and_used
841 ; printMinimalImports minimal_imports }
843 used_names, all_used_names :: NameSet
844 used_names = findUses (tcg_dus gbl_env) emptyNameSet
845 -- NB: currently, if f x = g, we only treat 'g' as used if 'f' is used
848 all_used_names = used_names `unionNameSets`
849 mkNameSet (mapCatMaybes nameParent_maybe (nameSetToList used_names))
850 -- A use of C implies a use of T,
851 -- if C was brought into scope by T(..) or T(C)
853 -- Collect the defined names from the in-scope environment
854 defined_names :: [GlobalRdrElt]
855 defined_names = globalRdrEnvElts (tcg_rdr_env gbl_env)
857 -- Note that defined_and_used, defined_but_not_used
858 -- are both [GRE]; that's why we need defined_and_used
859 -- rather than just all_used_names
860 defined_and_used, defined_but_not_used :: [GlobalRdrElt]
861 (defined_and_used, defined_but_not_used)
862 = partition (gre_is_used all_used_names) defined_names
864 -- Filter out the ones that are
865 -- (a) defined in this module, and
866 -- (b) not defined by a 'deriving' clause
867 -- The latter have an Internal Name, so we can filter them out easily
868 unused_locals :: [GlobalRdrElt]
869 unused_locals = filter is_unused_local defined_but_not_used
870 is_unused_local :: GlobalRdrElt -> Bool
871 is_unused_local gre = isLocalGRE gre && isExternalName (gre_name gre)
873 unused_imports :: [GlobalRdrElt]
874 unused_imports = filter unused_imp defined_but_not_used
875 unused_imp (GRE {gre_prov = Imported imp_specs})
876 = not (all (module_unused . importSpecModule) imp_specs)
877 && or [exp | ImpSpec { is_item = ImpSome { is_explicit = exp } } <- imp_specs]
878 -- Don't complain about unused imports if we've already said the
879 -- entire import is unused
880 unused_imp other = False
882 -- To figure out the minimal set of imports, start with the things
883 -- that are in scope (i.e. in gbl_env). Then just combine them
884 -- into a bunch of avails, so they are properly grouped
886 -- BUG WARNING: this does not deal properly with qualified imports!
887 minimal_imports :: FiniteMap ModuleName AvailEnv
888 minimal_imports0 = foldr add_expall emptyFM expall_mods
889 minimal_imports1 = foldr add_name minimal_imports0 defined_and_used
890 minimal_imports = foldr add_inst_mod minimal_imports1 direct_import_mods
891 -- The last line makes sure that we retain all direct imports
892 -- even if we import nothing explicitly.
893 -- It's not necessarily redundant to import such modules. Consider
897 -- The import M() is not *necessarily* redundant, even if
898 -- we suck in no instance decls from M (e.g. it contains
899 -- no instance decls, or This contains no code). It may be
900 -- that we import M solely to ensure that M's orphan instance
901 -- decls (or those in its imports) are visible to people who
902 -- import This. Sigh.
903 -- There's really no good way to detect this, so the error message
904 -- in RnEnv.warnUnusedModules is weakened instead
906 -- We've carefully preserved the provenance so that we can
907 -- construct minimal imports that import the name by (one of)
908 -- the same route(s) as the programmer originally did.
909 add_name (GRE {gre_name = n, gre_prov = Imported imp_specs}) acc
910 = addToFM_C plusAvailEnv acc (importSpecModule (head imp_specs))
911 (unitAvailEnv (mk_avail n (nameParent_maybe n)))
915 -- Modules mentioned as 'module M' in the export list
916 expall_mods = case export_decls of
918 Just es -> [m | L _ (IEModuleContents m) <- es]
920 -- This is really bogus. The idea is that if we see 'module M' in
921 -- the export list we must retain the import decls that drive it
922 -- If we aren't careful we might see
923 -- module A( module M ) where
926 -- and suppose that N exports everything that M does. Then we
927 -- must not drop the import of M even though N brings it all into
930 -- BUG WARNING: 'module M' exports aside, what if M.x is mentioned?!
932 -- The reason that add_expall is bogus is that it doesn't take
933 -- qualified imports into account. But it's an improvement.
934 add_expall mod acc = addToFM_C plusAvailEnv acc mod emptyAvailEnv
936 -- n is the name of the thing, p is the name of its parent
937 mk_avail n (Just p) = AvailTC p [p,n]
938 mk_avail n Nothing | isTcOcc (nameOccName n) = AvailTC n [n]
939 | otherwise = Avail n
941 add_inst_mod (mod,_,_) acc
942 | mod_name `elemFM` acc = acc -- We import something already
943 | otherwise = addToFM acc mod_name emptyAvailEnv
945 mod_name = moduleName mod
946 -- Add an empty collection of imports for a module
947 -- from which we have sucked only instance decls
949 imports = tcg_imports gbl_env
951 direct_import_mods :: [(Module, Bool, SrcSpan)]
952 -- See the type of the imp_mods for this triple
953 direct_import_mods = moduleEnvElts (imp_mods imports)
955 -- unused_imp_mods are the directly-imported modules
956 -- that are not mentioned in minimal_imports1
957 -- [Note: not 'minimal_imports', because that includes directly-imported
958 -- modules even if we use nothing from them; see notes above]
960 -- BUG WARNING: does not deal correctly with multiple imports of the same module
961 -- becuase direct_import_mods has only one entry per module
962 unused_imp_mods = [(mod_name,loc) | (mod,no_imp,loc) <- direct_import_mods,
963 let mod_name = moduleName mod,
964 not (mod_name `elemFM` minimal_imports1),
967 -- The not no_imp part is not to complain about
968 -- import M (), which is an idiom for importing
969 -- instance declarations
971 module_unused :: ModuleName -> Bool
972 module_unused mod = any (((==) mod) . fst) unused_imp_mods
974 ---------------------
975 warnDuplicateImports :: [GlobalRdrElt] -> RnM ()
976 -- Given the GREs for names that are used, figure out which imports
977 -- could be omitted without changing the top-level environment.
979 -- NB: Given import Foo( T )
980 -- import qualified Foo
981 -- we do not report a duplicate import, even though Foo.T is brought
982 -- into scope by both, because there's nothing you can *omit* without
983 -- changing the top-level environment. So we complain only if it's
984 -- explicitly named in both imports or neither.
986 -- Furthermore, we complain about Foo.T only if
987 -- there is no complaint about (unqualified) T
989 warnDuplicateImports gres
990 = ifOptM Opt_WarnUnusedImports $
991 sequenceM_ [ warn name pr
992 -- The 'head' picks the first offending group
993 -- for this particular name
994 | GRE { gre_name = name, gre_prov = Imported imps } <- gres
995 , pr <- redundants imps ]
997 warn name (red_imp, cov_imp)
998 = addWarnAt (importSpecLoc red_imp)
999 (vcat [ptext SLIT("Redundant import of:") <+> quotes pp_name,
1000 ptext SLIT("It is also") <+> ppr cov_imp])
1002 pp_name | is_qual red_decl = ppr (is_as red_decl) <> dot <> ppr occ
1003 | otherwise = ppr occ
1004 occ = nameOccName name
1005 red_decl = is_decl red_imp
1007 redundants :: [ImportSpec] -> [(ImportSpec,ImportSpec)]
1008 -- The returned pair is (redundant-import, covering-import)
1010 = [ (red_imp, cov_imp)
1012 , cov_imp <- take 1 (filter (covers red_imp) imps) ]
1014 -- "red_imp" is a putative redundant import
1015 -- "cov_imp" potentially covers it
1016 -- This test decides whether red_imp could be dropped
1018 -- NOTE: currently the test does not warn about
1021 -- even if the same underlying 'x' is involved, because dropping
1022 -- either import would change the qualified names in scope (M.x, N.x)
1023 -- But if the qualified names aren't used, the import is indeed redundant
1024 -- Sadly we don't know that. Oh well.
1025 covers red_imp@(ImpSpec { is_decl = red_decl, is_item = red_item })
1026 cov_imp@(ImpSpec { is_decl = cov_decl, is_item = cov_item })
1027 | red_loc == cov_loc
1028 = False -- Ignore diagonal elements
1029 | not (is_as red_decl == is_as cov_decl)
1030 = False -- They bring into scope different qualified names
1031 | not (is_qual red_decl) && is_qual cov_decl
1032 = False -- Covering one doesn't bring unqualified name into scope
1034 = not cov_selective -- Redundant one is selective and covering one isn't
1035 || red_later -- Both are explicit; tie-break using red_later
1037 = not cov_selective -- Neither import is selective
1038 && (is_mod red_decl == is_mod cov_decl) -- They import the same module
1039 && red_later -- Tie-break
1041 red_loc = importSpecLoc red_imp
1042 cov_loc = importSpecLoc cov_imp
1043 red_later = red_loc > cov_loc
1044 cov_selective = selectiveImpItem cov_item
1045 red_selective = selectiveImpItem red_item
1047 selectiveImpItem :: ImpItemSpec -> Bool
1048 selectiveImpItem ImpAll = False
1049 selectiveImpItem (ImpSome {}) = True
1051 -- ToDo: deal with original imports with 'qualified' and 'as M' clauses
1052 printMinimalImports :: FiniteMap ModuleName AvailEnv -- Minimal imports
1054 printMinimalImports imps
1055 = ifOptM Opt_D_dump_minimal_imports $ do {
1057 mod_ies <- mappM to_ies (fmToList imps) ;
1058 this_mod <- getModule ;
1059 rdr_env <- getGlobalRdrEnv ;
1060 ioToTcRn (do { h <- openFile (mkFilename this_mod) WriteMode ;
1061 printForUser h (mkPrintUnqualified rdr_env)
1062 (vcat (map ppr_mod_ie mod_ies)) })
1065 mkFilename this_mod = moduleNameString (moduleName this_mod) ++ ".imports"
1066 ppr_mod_ie (mod_name, ies)
1067 | mod_name == moduleName pRELUDE
1069 | null ies -- Nothing except instances comes from here
1070 = ptext SLIT("import") <+> ppr mod_name <> ptext SLIT("() -- Instances only")
1072 = ptext SLIT("import") <+> ppr mod_name <>
1073 parens (fsep (punctuate comma (map ppr ies)))
1075 to_ies (mod, avail_env) = do ies <- mapM to_ie (availEnvElts avail_env)
1078 to_ie :: AvailInfo -> RnM (IE Name)
1079 -- The main trick here is that if we're importing all the constructors
1080 -- we want to say "T(..)", but if we're importing only a subset we want
1081 -- to say "T(A,B,C)". So we have to find out what the module exports.
1082 to_ie (Avail n) = returnM (IEVar n)
1083 to_ie (AvailTC n [m]) = ASSERT( n==m )
1084 returnM (IEThingAbs n)
1085 to_ie (AvailTC n ns)
1086 = loadSrcInterface doc n_mod False `thenM` \ iface ->
1087 case [xs | (m,as) <- mi_exports iface,
1088 moduleName m == n_mod,
1090 x == nameOccName n] of
1091 [xs] | all_used xs -> returnM (IEThingAll n)
1092 | otherwise -> returnM (IEThingWith n (filter (/= n) ns))
1093 other -> pprTrace "to_ie" (ppr n <+> ppr n_mod <+> ppr other) $
1096 all_used avail_occs = all (`elem` map nameOccName ns) avail_occs
1097 doc = text "Compute minimal imports from" <+> ppr n
1098 n_mod = moduleName (nameModule n)
1102 %************************************************************************
1106 %************************************************************************
1109 badImportItemErr iface decl_spec ie
1110 = sep [ptext SLIT("Module"), quotes (ppr (is_mod decl_spec)), source_import,
1111 ptext SLIT("does not export"), quotes (ppr ie)]
1113 source_import | mi_boot iface = ptext SLIT("(hi-boot interface)")
1116 dodgyImportWarn item = dodgyMsg (ptext SLIT("import")) item
1117 dodgyExportWarn item = dodgyMsg (ptext SLIT("export")) item
1120 = sep [ ptext SLIT("The") <+> kind <+> ptext SLIT("item") <+> quotes (ppr (IEThingAll tc)),
1121 ptext SLIT("suggests that") <+> quotes (ppr tc) <+> ptext SLIT("has constructor or class methods"),
1122 ptext SLIT("but it has none; it is a type synonym or abstract type or class") ]
1125 = hsep [ ptext SLIT("Unknown module in export list: module"), quotes (ppr mod)]
1127 exportItemErr export_item
1128 = sep [ ptext SLIT("The export item") <+> quotes (ppr export_item),
1129 ptext SLIT("attempts to export constructors or class methods that are not visible here") ]
1131 typeItemErr name wherestr
1132 = sep [ ptext SLIT("Using 'type' tag on") <+> quotes (ppr name) <+> wherestr,
1133 ptext SLIT("Use -findexed-types to enable this extension") ]
1135 exportClashErr global_env name1 name2 ie1 ie2
1136 = vcat [ ptext SLIT("Conflicting exports for") <+> quotes (ppr occ) <> colon
1137 , ppr_export ie1 name1
1138 , ppr_export ie2 name2 ]
1140 occ = nameOccName name1
1141 ppr_export ie name = nest 2 (quotes (ppr ie) <+> ptext SLIT("exports") <+>
1142 quotes (ppr name) <+> pprNameProvenance (get_gre name))
1144 -- get_gre finds a GRE for the Name, so that we can show its provenance
1146 = case lookupGRE_Name global_env name of
1148 [] -> pprPanic "exportClashErr" (ppr name)
1150 addDupDeclErr :: Name -> Name -> TcRn ()
1151 addDupDeclErr name_a name_b
1152 = addErrAt (srcLocSpan loc2) $
1153 vcat [ptext SLIT("Multiple declarations of") <+> quotes (ppr name1),
1154 ptext SLIT("Declared at:") <+> vcat [ppr (nameSrcLoc name1), ppr loc2]]
1156 loc2 = nameSrcLoc name2
1157 (name1,name2) | nameSrcLoc name_a > nameSrcLoc name_b = (name_b,name_a)
1158 | otherwise = (name_a,name_b)
1159 -- Report the error at the later location
1161 dupExportWarn occ_name ie1 ie2
1162 = hsep [quotes (ppr occ_name),
1163 ptext SLIT("is exported by"), quotes (ppr ie1),
1164 ptext SLIT("and"), quotes (ppr ie2)]
1167 = hsep [ptext SLIT("Duplicate"),
1168 quotes (ptext SLIT("Module") <+> ppr mod),
1169 ptext SLIT("in export list")]
1171 moduleDeprec mod txt
1172 = sep [ ptext SLIT("Module") <+> quotes (ppr mod) <+> ptext SLIT("is deprecated:"),