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(..) )
17 import HsSyn ( IE(..), ieName, ImportDecl(..), LImportDecl,
18 ForeignDecl(..), HsGroup(..), HsValBinds(..),
19 Sig(..), collectHsBindLocatedBinders, tyClDeclNames,
22 import IfaceEnv ( ifaceExportNames )
23 import LoadIface ( loadSrcInterface )
24 import TcRnMonad hiding (LIE)
27 import PrelNames ( pRELUDE, isUnboundName, main_RDR_Unqual )
28 import Module ( Module, moduleString, unitModuleEnv,
29 lookupModuleEnv, moduleEnvElts, foldModuleEnv )
30 import Name ( Name, nameSrcLoc, nameOccName, nameModule, isWiredInName,
31 nameParent, nameParent_maybe, isExternalName,
35 import OccName ( srcDataName, isTcOcc, pprNonVarNameSpace,
37 OccEnv, mkOccEnv, lookupOccEnv, emptyOccEnv,
39 import HscTypes ( GenAvailInfo(..), AvailInfo,
40 HomePackageTable, PackageIfaceTable,
42 Deprecs(..), ModIface(..), Dependencies(..),
43 lookupIface, ExternalPackageState(..)
45 import Packages ( PackageIdH(..) )
46 import RdrName ( RdrName, rdrNameOcc, setRdrNameSpace,
47 GlobalRdrEnv, mkGlobalRdrEnv, GlobalRdrElt(..),
48 emptyGlobalRdrEnv, plusGlobalRdrEnv, globalRdrEnvElts,
49 extendGlobalRdrEnv, lookupGlobalRdrEnv, unQualOK, lookupGRE_Name,
50 Provenance(..), ImportSpec(..), ImpDeclSpec(..), ImpItemSpec(..),
51 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(..) )
65 %************************************************************************
69 %************************************************************************
72 rnImports :: [LImportDecl RdrName] -> RnM [LImportDecl Name]
74 -- PROCESS IMPORT DECLS
75 -- Do the non {- SOURCE -} ones first, so that we get a helpful
76 -- warning for {- SOURCE -} ones that are unnecessary
77 = do this_mod <- getModule
78 implicit_prelude <- doptM Opt_ImplicitPrelude
79 let all_imports = mk_prel_imports this_mod implicit_prelude ++ imports
80 (source, ordinary) = partition is_source_import all_imports
81 is_source_import (L _ (ImportDecl _ is_boot _ _ _)) = is_boot
82 get_imports = importsFromImportDeclDirect this_mod
84 stuff1 <- mapM get_imports ordinary
85 stuff2 <- mapM get_imports source
86 return (stuff1 ++ stuff2)
88 -- NB: opt_NoImplicitPrelude is slightly different to import Prelude ();
89 -- because the former doesn't even look at Prelude.hi for instance
90 -- declarations, whereas the latter does.
91 mk_prel_imports this_mod implicit_prelude
93 || explicit_prelude_import
94 || not implicit_prelude
96 | otherwise = [preludeImportDecl]
97 explicit_prelude_import
98 = notNull [ () | L _ (ImportDecl mod _ _ _ _) <- imports,
99 unLoc mod == pRELUDE ]
101 preludeImportDecl :: LImportDecl RdrName
104 ImportDecl (L loc pRELUDE)
105 False {- Not a boot interface -}
106 False {- Not qualified -}
107 Nothing {- No "as" -}
108 Nothing {- No import list -}
110 loc = mkGeneralSrcSpan FSLIT("Implicit import declaration")
112 mkRdrEnvAndImports :: [LImportDecl Name] -> RnM (GlobalRdrEnv, ImportAvails)
113 mkRdrEnvAndImports imports
114 = do this_mod <- getModule
115 let get_imports = importsFromImportDecl this_mod
116 stuff <- mapM get_imports imports
117 let (imp_gbl_envs, imp_avails) = unzip stuff
118 gbl_env :: GlobalRdrEnv
119 gbl_env = foldr plusGlobalRdrEnv emptyGlobalRdrEnv imp_gbl_envs
121 all_avails :: ImportAvails
122 all_avails = foldr plusImportAvails emptyImportAvails imp_avails
124 return (gbl_env, all_avails)
129 rnImportDecl :: ModIface -> ImpDeclSpec -> ImportDecl RdrName -> NameSet -> RnM (ImportDecl Name)
130 rnImportDecl iface decl_spec (ImportDecl loc_imp_mod_name want_boot qual_only as_mod Nothing) all_names
131 = return $ ImportDecl loc_imp_mod_name want_boot qual_only as_mod Nothing
132 rnImportDecl iface decl_spec (ImportDecl loc_imp_mod_name want_boot qual_only as_mod (Just (want_hiding,import_items))) all_names
133 = do import_items_mbs <- mapM (srcSpanWrapper) import_items
134 let rn_import_items = concat . catMaybes $ import_items_mbs
135 return $ ImportDecl loc_imp_mod_name want_boot qual_only as_mod (Just (want_hiding,rn_import_items))
137 srcSpanWrapper (L span ieRdr)
139 case get_item ieRdr of
141 -> do addErr (badImportItemErr iface decl_spec ieRdr)
144 -> return (Just [L span ie | ie <- ieNames])
145 occ_env :: OccEnv Name -- Maps OccName to corresponding Name
146 occ_env = mkOccEnv [(nameOccName n, n) | n <- nameSetToList all_names]
147 -- This env will have entries for data constructors too,
148 -- they won't make any difference because naked entities like T
149 -- in an import list map to TcOccs, not VarOccs.
151 sub_env :: NameEnv [Name]
152 sub_env = mkSubNameEnv all_names
154 get_item :: IE RdrName -> Maybe [IE Name]
155 -- Empty result for a bad item.
156 -- Singleton result is typical case.
157 -- Can have two when we are hiding, and mention C which might be
158 -- both a class and a data constructor.
159 get_item item@(IEModuleContents _)
162 get_item (IEThingAll tc)
163 = do name <- check_name tc
164 return [IEThingAll name]
166 -> -- This occurs when you import T(..), but
167 -- only export T abstractly. The single [n]
168 -- in the AvailTC is the type or class itself
169 ifOptM Opt_WarnDodgyImports (addWarn (dodgyImportWarn tc)) `thenM_`
170 return [ IEThingAll n ]
172 names -> return [ IEThingAll n | n <- names ]
175 get_item (IEThingAbs tc)
176 | want_hiding -- hiding ( C )
177 -- Here the 'C' can be a data constructor
178 -- *or* a type/class, or even both
179 = case catMaybes [check_name tc, check_name (setRdrNameSpace tc srcDataName)] of
181 names -> return [ IEThingAbs n | n <- names ]
183 = do name <- check_name tc
184 return [IEThingAbs name]
185 get_item (IEThingWith n ns) -- import (C (A,B))
186 = do name <- check_name n
187 let env = mkOccEnv [(nameOccName s, s) | s <- subNames sub_env name]
188 mb_names = map (lookupOccEnv env . rdrNameOcc) ns
189 names <- sequence mb_names
190 return [IEThingWith name names]
193 = do name <- check_name n
196 check_name :: RdrName -> Maybe Name
198 = lookupOccEnv occ_env (rdrNameOcc rdrName)
201 importsFromImportDeclDirect :: Module
202 -> LImportDecl RdrName
203 -> RnM (LImportDecl Name)
204 importsFromImportDeclDirect this_mod
205 (L loc importDecl@(ImportDecl loc_imp_mod_name want_boot qual_only as_mod imp_details))
207 do iface <- loadSrcInterface doc imp_mod_name want_boot
208 let filtered_exports = filter not_this_mod (mi_exports iface)
209 not_this_mod (mod,_) = mod /= this_mod
211 -- If the module exports anything defined in this module, just ignore it.
212 -- Reason: otherwise it looks as if there are two local definition sites
213 -- for the thing, and an error gets reported. Easiest thing is just to
214 -- filter them out up front. This situation only arises if a module
215 -- imports itself, or another module that imported it. (Necessarily,
216 -- this invoves a loop.)
218 -- Tiresome consequence: if you say
223 -- module B( AType ) where
224 -- import {-# SOURCE #-} A( AType )
226 -- then you'll get a 'B does not export AType' message. Oh well.
228 qual_mod_name = case as_mod of
229 Nothing -> imp_mod_name
230 Just another_name -> another_name
231 imp_spec = ImpDeclSpec { is_mod = imp_mod_name, is_qual = qual_only,
232 is_dloc = loc, is_as = qual_mod_name }
234 -- Get the total imports, and filter them according to the import list
235 total_avails <- ifaceExportNames (mi_exports iface)
236 importDecl' <- rnImportDecl iface imp_spec importDecl total_avails
237 return (L loc importDecl')
238 where imp_mod_name = unLoc loc_imp_mod_name
239 doc = ppr imp_mod_name <+> ptext SLIT("is directly imported")
241 importsFromImportDecl :: Module
243 -> RnM (GlobalRdrEnv, ImportAvails)
245 importsFromImportDecl this_mod
246 (L loc (ImportDecl loc_imp_mod_name want_boot qual_only as_mod imp_details))
250 -- If there's an error in loadInterface, (e.g. interface
251 -- file not found) we get lots of spurious errors from 'filterImports'
253 imp_mod_name = unLoc loc_imp_mod_name
254 doc = ppr imp_mod_name <+> ptext SLIT("is directly imported")
256 loadSrcInterface doc imp_mod_name want_boot `thenM` \ iface ->
258 -- Compiler sanity check: if the import didn't say
259 -- {-# SOURCE #-} we should not get a hi-boot file
260 WARN( not want_boot && mi_boot iface, ppr imp_mod_name )
262 -- Issue a user warning for a redundant {- SOURCE -} import
263 -- NB that we arrange to read all the ordinary imports before
264 -- any of the {- SOURCE -} imports
265 warnIf (want_boot && not (mi_boot iface))
266 (warnRedundantSourceImport imp_mod_name) `thenM_`
269 imp_mod = mi_module iface
270 deprecs = mi_deprecs iface
271 is_orph = mi_orphan iface
274 filtered_exports = filter not_this_mod (mi_exports iface)
275 not_this_mod (mod,_) = mod /= this_mod
276 -- If the module exports anything defined in this module, just ignore it.
277 -- Reason: otherwise it looks as if there are two local definition sites
278 -- for the thing, and an error gets reported. Easiest thing is just to
279 -- filter them out up front. This situation only arises if a module
280 -- imports itself, or another module that imported it. (Necessarily,
281 -- this invoves a loop.)
283 -- Tiresome consequence: if you say
288 -- module B( AType ) where
289 -- import {-# SOURCE #-} A( AType )
291 -- then you'll get a 'B does not export AType' message. Oh well.
293 qual_mod_name = case as_mod of
294 Nothing -> imp_mod_name
295 Just another_name -> another_name
296 imp_spec = ImpDeclSpec { is_mod = imp_mod_name, is_qual = qual_only,
297 is_dloc = loc, is_as = qual_mod_name }
299 -- Get the total imports, and filter them according to the import list
300 ifaceExportNames filtered_exports `thenM` \ total_avails ->
301 filterImports iface imp_spec
302 imp_details total_avails `thenM` \ (avail_env, gbl_env) ->
304 getDOpts `thenM` \ dflags ->
307 -- Compute new transitive dependencies
309 orphans | is_orph = ASSERT( not (imp_mod_name `elem` dep_orphs deps) )
310 imp_mod_name : dep_orphs deps
311 | otherwise = dep_orphs deps
313 (dependent_mods, dependent_pkgs)
314 = case mi_package iface of
316 -- Imported module is from the home package
317 -- Take its dependent modules and add imp_mod itself
318 -- Take its dependent packages unchanged
320 -- NB: (dep_mods deps) might include a hi-boot file
321 -- for the module being compiled, CM. Do *not* filter
322 -- this out (as we used to), because when we've
323 -- finished dealing with the direct imports we want to
324 -- know if any of them depended on CM.hi-boot, in
325 -- which case we should do the hi-boot consistency
326 -- check. See LoadIface.loadHiBootInterface
327 ((imp_mod_name, want_boot) : dep_mods deps, dep_pkgs deps)
330 -- Imported module is from another package
331 -- Dump the dependent modules
332 -- Add the package imp_mod comes from to the dependent packages
333 ASSERT2( not (pkg `elem` dep_pkgs deps), ppr pkg <+> ppr (dep_pkgs deps) )
334 ([], pkg : dep_pkgs deps)
336 -- True <=> import M ()
337 import_all = case imp_details of
338 Just (is_hiding, ls) -> not is_hiding && null ls
341 -- unqual_avails is the Avails that are visible in *unqualified* form
342 -- We need to know this so we know what to export when we see
343 -- module M ( module P ) where ...
344 -- Then we must export whatever came from P unqualified.
345 imports = ImportAvails {
346 imp_env = unitModuleEnv qual_mod_name avail_env,
347 imp_mods = unitModuleEnv imp_mod (imp_mod, import_all, loc),
349 imp_dep_mods = mkModDeps dependent_mods,
350 imp_dep_pkgs = dependent_pkgs }
353 -- Complain if we import a deprecated module
354 ifOptM Opt_WarnDeprecations (
356 DeprecAll txt -> addWarn (moduleDeprec imp_mod_name txt)
360 returnM (gbl_env, imports)
362 warnRedundantSourceImport mod_name
363 = ptext SLIT("Unnecessary {- SOURCE -} in the import of module")
364 <+> quotes (ppr mod_name)
368 %************************************************************************
370 importsFromLocalDecls
372 %************************************************************************
374 From the top-level declarations of this module produce
375 * the lexical environment
377 created by its bindings.
379 Complain about duplicate bindings
382 importsFromLocalDecls :: HsGroup RdrName -> RnM TcGblEnv
383 importsFromLocalDecls group
384 = do { gbl_env <- getGblEnv
386 ; names <- getLocalDeclBinders gbl_env group
388 ; implicit_prelude <- doptM Opt_ImplicitPrelude
390 -- Optimisation: filter out names for built-in syntax
391 -- They just clutter up the environment (esp tuples), and the parser
392 -- will generate Exact RdrNames for them, so the cluttered
393 -- envt is no use. To avoid doing this filter all the time,
394 -- we use -fno-implicit-prelude as a clue that the filter is
395 -- worth while. Really, it's only useful for GHC.Base and GHC.Tuple.
397 -- It's worth doing because it makes the environment smaller for
398 -- every module that imports the Prelude
400 -- Note: don't filter the gbl_env (hence all_names, not filered_all_names
401 -- in defn of gres above). Stupid reason: when parsing
402 -- data type decls, the constructors start as Exact tycon-names,
403 -- and then get turned into data con names by zapping the name space;
404 -- but that stops them being Exact, so they get looked up.
405 -- Ditto in fixity decls; e.g. infix 5 :
406 -- Sigh. It doesn't matter because it only affects the Data.Tuple really.
407 -- The important thing is to trim down the exports.
409 | implicit_prelude = names
410 | otherwise = filter (not . isBuiltInSyntax) names ;
412 ; this_mod = tcg_mod gbl_env
413 ; imports = emptyImportAvails {
414 imp_env = unitModuleEnv this_mod $
415 mkNameSet filtered_names
419 ; rdr_env' <- extendRdrEnvRn (tcg_rdr_env gbl_env) names
421 ; returnM (gbl_env { tcg_rdr_env = rdr_env',
422 tcg_imports = imports `plusImportAvails` tcg_imports gbl_env })
425 extendRdrEnvRn :: GlobalRdrEnv -> [Name] -> RnM GlobalRdrEnv
426 -- Add the new locally-bound names one by one, checking for duplicates as
427 -- we do so. Remember that in Template Haskell the duplicates
428 -- might *already be* in the GlobalRdrEnv from higher up the module
429 extendRdrEnvRn rdr_env names
430 = foldlM add_local rdr_env names
432 add_local rdr_env name
433 | gres <- lookupGlobalRdrEnv rdr_env (nameOccName name)
434 , (dup_gre:_) <- filter isLocalGRE gres -- Check for existing *local* defns
435 = do { addDupDeclErr (gre_name dup_gre) name
438 = return (extendGlobalRdrEnv rdr_env new_gre)
440 new_gre = GRE {gre_name = name, gre_prov = LocalDef}
443 @getLocalDeclBinders@ returns the names for an @HsDecl@. It's
444 used for source code.
446 *** See "THE NAMING STORY" in HsDecls ****
449 getLocalDeclBinders :: TcGblEnv -> HsGroup RdrName -> RnM [Name]
450 getLocalDeclBinders gbl_env (HsGroup {hs_valds = ValBindsIn val_decls val_sigs,
451 hs_tyclds = tycl_decls,
452 hs_fords = foreign_decls })
453 = do { tc_names_s <- mappM new_tc tycl_decls
454 ; val_names <- mappM new_simple val_bndrs
455 ; return (foldr (++) val_names tc_names_s) }
457 mod = tcg_mod gbl_env
458 is_hs_boot = isHsBoot (tcg_src gbl_env) ;
459 val_bndrs | is_hs_boot = sig_hs_bndrs
460 | otherwise = for_hs_bndrs ++ val_hs_bndrs
461 -- In a hs-boot file, the value binders come from the
462 -- *signatures*, and there should be no foreign binders
464 new_simple rdr_name = newTopSrcBinder mod Nothing rdr_name
466 sig_hs_bndrs = [nm | L _ (TypeSig nm _) <- val_sigs]
467 val_hs_bndrs = collectHsBindLocatedBinders val_decls
468 for_hs_bndrs = [nm | L _ (ForeignImport nm _ _ _) <- foreign_decls]
471 = do { main_name <- newTopSrcBinder mod Nothing main_rdr
472 ; sub_names <- mappM (newTopSrcBinder mod (Just main_name)) sub_rdrs
473 ; return (main_name : sub_names) }
475 (main_rdr : sub_rdrs) = tyClDeclNames (unLoc tc_decl)
479 %************************************************************************
481 \subsection{Filtering imports}
483 %************************************************************************
485 @filterImports@ takes the @ExportEnv@ telling what the imported module makes
486 available, and filters it through the import spec (if any).
489 filterImports :: ModIface
490 -> ImpDeclSpec -- The span for the entire import decl
491 -> Maybe (Bool, [LIE Name]) -- Import spec; True => hiding
492 -> NameSet -- What's available
493 -> RnM (NameSet, -- What's imported (qualified or unqualified)
494 GlobalRdrEnv) -- Same again, but in GRE form
496 -- Complains if import spec mentions things that the module doesn't export
497 -- Warns/informs if import spec contains duplicates.
499 mkGenericRdrEnv decl_spec names
500 = mkGlobalRdrEnv [ GRE { gre_name = name, gre_prov = Imported [imp_spec] }
501 | name <- nameSetToList names ]
503 imp_spec = ImpSpec { is_decl = decl_spec, is_item = ImpAll }
505 filterImports iface decl_spec Nothing all_names
506 = return (all_names, mkGenericRdrEnv decl_spec all_names)
508 filterImports iface decl_spec (Just (want_hiding, import_items)) all_names
509 = mapM (addLocM get_item) import_items >>= \gres_s ->
510 let gres = concat gres_s
511 specified_names = mkNameSet (map gre_name gres)
512 in if not want_hiding then
513 return (specified_names, mkGlobalRdrEnv gres)
514 else let keep n = not (n `elemNameSet` specified_names)
515 pruned_avails = filterNameSet keep all_names
516 in return (pruned_avails, mkGenericRdrEnv decl_spec pruned_avails)
518 sub_env :: NameEnv [Name] -- Classify each name by its parent
519 sub_env = mkSubNameEnv all_names
521 succeed_with :: Bool -> [Name] -> RnM [GlobalRdrElt]
522 succeed_with all_explicit names
523 = do { loc <- getSrcSpanM
524 ; returnM (map (mk_gre loc) names) }
526 mk_gre loc name = GRE { gre_name = name,
527 gre_prov = Imported [imp_spec] }
529 imp_spec = ImpSpec { is_decl = decl_spec, is_item = item_spec }
530 item_spec = ImpSome { is_explicit = explicit, is_iloc = loc }
531 explicit = all_explicit || isNothing (nameParent_maybe name)
533 get_item :: IE Name -> RnM [GlobalRdrElt]
534 -- Empty result for a bad item.
535 -- Singleton result is typical case.
536 -- Can have two when we are hiding, and mention C which might be
537 -- both a class and a data constructor.
538 get_item item@(IEModuleContents _)
539 -- This case should be filtered out by 'rnImports'.
540 = panic "filterImports: IEModuleContents?"
542 get_item (IEThingAll name)
543 = case subNames sub_env name of
544 [] -> do ifOptM Opt_WarnDodgyImports (addWarn (dodgyImportWarn name))
545 succeed_with False [name]
546 names -> succeed_with False (name:names)
548 get_item (IEThingAbs name)
549 = succeed_with True [name]
551 get_item (IEThingWith name names)
552 = succeed_with True (name:names)
553 get_item (IEVar name)
554 = succeed_with True [name]
559 %************************************************************************
561 \subsection{Export list processing}
563 %************************************************************************
565 Processing the export list.
567 You might think that we should record things that appear in the export
568 list as ``occurrences'' (using @addOccurrenceName@), but you'd be
569 wrong. We do check (here) that they are in scope, but there is no
570 need to slurp in their actual declaration (which is what
571 @addOccurrenceName@ forces).
573 Indeed, doing so would big trouble when compiling @PrelBase@, because
574 it re-exports @GHC@, which includes @takeMVar#@, whose type includes
575 @ConcBase.StateAndSynchVar#@, and so on...
578 type ExportAccum -- The type of the accumulating parameter of
579 -- the main worker function in rnExports
580 = ([Module], -- 'module M's seen so far
581 ExportOccMap, -- Tracks exported occurrence names
582 NameSet) -- The accumulated exported stuff
583 emptyExportAccum = ([], emptyOccEnv, emptyNameSet)
585 type ExportOccMap = OccEnv (Name, IE Name)
586 -- Tracks what a particular exported OccName
587 -- in an export list refers to, and which item
588 -- it came from. It's illegal to export two distinct things
589 -- that have the same occurrence name
591 rnExports :: Maybe [LIE RdrName]
592 -> RnM (Maybe [LIE Name])
593 rnExports Nothing = return Nothing
594 rnExports (Just exports)
595 = do TcGblEnv { tcg_imports = ImportAvails { imp_env = imp_env } } <- getGblEnv
596 let sub_env :: NameEnv [Name] -- Classify each name by its parent
597 sub_env = mkSubNameEnv (foldModuleEnv unionNameSets emptyNameSet imp_env)
601 rnExport (IEVar rdrName)
602 = do name <- lookupGlobalOccRn rdrName
604 rnExport (IEThingAbs rdrName)
605 = do name <- lookupGlobalOccRn rdrName
606 return (IEThingAbs name)
607 rnExport (IEThingAll rdrName)
608 = do name <- lookupGlobalOccRn rdrName
609 return (IEThingAll name)
610 rnExport (IEThingWith rdrName rdrNames)
611 = do name <- lookupGlobalOccRn rdrName
612 let env = mkOccEnv [(nameOccName s, s) | s <- subNames sub_env name]
613 mb_names = map (lookupOccEnv env . rdrNameOcc) rdrNames
614 if any isNothing mb_names
615 then -- The export error will be reporting in 'mkExportNameSet'
616 return (IEThingWith name [])
617 else return (IEThingWith name (catMaybes mb_names))
618 rnExport (IEModuleContents mod)
619 = return (IEModuleContents mod)
620 rn_exports <- mapM (inLoc rnExport) exports
621 return (Just rn_exports)
623 mkExportNameSet :: Bool -- False => no 'module M(..) where' header at all
624 -> Maybe [LIE Name] -- Nothing => no explicit export list
626 -- Complains if two distinct exports have same OccName
627 -- Warns about identical exports.
628 -- Complains about exports items not in scope
630 mkExportNameSet explicit_mod exports
631 = do TcGblEnv { tcg_rdr_env = rdr_env,
632 tcg_imports = imports } <- getGblEnv
634 -- If the module header is omitted altogether, then behave
635 -- as if the user had written "module Main(main) where..."
636 -- EXCEPT in interactive mode, when we behave as if he had
637 -- written "module Main where ..."
638 -- Reason: don't want to complain about 'main' not in scope
639 -- in interactive mode
640 ghci_mode <- getGhciMode
641 real_exports <- case () of
644 | ghci_mode == Interactive
647 -> do mainName <- lookupGlobalOccRn main_RDR_Unqual
648 return (Just [noLoc (IEVar mainName)])
649 -- ToDo: the 'noLoc' here is unhelpful if 'main' turns out to be out of scope
650 exports_from_avail real_exports rdr_env imports
653 exports_from_avail Nothing rdr_env imports
654 = -- Export all locally-defined things
655 -- We do this by filtering the global RdrEnv,
656 -- keeping only things that are locally-defined
657 return (mkNameSet [ gre_name gre
658 | gre <- globalRdrEnvElts rdr_env,
661 exports_from_avail (Just items) rdr_env (ImportAvails { imp_env = imp_env })
662 = do (_, _, exports) <- foldlM do_litem emptyExportAccum items
665 sub_env :: NameEnv [Name] -- Classify each name by its parent
666 sub_env = mkSubNameEnv (foldModuleEnv unionNameSets emptyNameSet imp_env)
668 do_litem :: ExportAccum -> LIE Name -> RnM ExportAccum
669 do_litem acc = addLocM (exports_from_item acc)
671 exports_from_item :: ExportAccum -> IE Name -> RnM ExportAccum
672 exports_from_item acc@(mods, occs, exports) ie@(IEModuleContents mod)
673 | mod `elem` mods -- Duplicate export of M
674 = do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
675 warnIf warn_dup_exports (dupModuleExport mod) ;
679 = case lookupModuleEnv imp_env mod of
680 Nothing -> do addErr (modExportErr mod)
683 -> do let new_exports = filterNameSet (inScopeUnqual rdr_env) names
684 -- This check_occs not only finds conflicts between this item
685 -- and others, but also internally within this item. That is,
686 -- if 'M.x' is in scope in several ways, we'll have several
687 -- members of mod_avails with the same OccName.
688 occs' <- check_occs ie occs (nameSetToList new_exports)
689 return (mod:mods, occs', exports `unionNameSets` new_exports)
691 exports_from_item acc@(mods, occs, exports) ie
692 = if isUnboundName (ieName ie)
693 then return acc -- Avoid error cascade
694 else let new_exports = filterAvail ie sub_env in
695 do checkErr (not (null new_exports)) (exportItemErr ie)
696 checkForDodgyExport ie new_exports
697 occs' <- check_occs ie occs new_exports
698 return (mods, occs', addListToNameSet exports new_exports)
700 -------------------------------
701 filterAvail :: IE Name -- Wanted
702 -> NameEnv [Name] -- Maps type/class names to their sub-names
705 filterAvail (IEVar n) subs = [n]
706 filterAvail (IEThingAbs n) subs = [n]
707 filterAvail (IEThingAll n) subs = n : subNames subs n
708 filterAvail (IEThingWith n ns) subs = n : ns
709 filterAvail (IEModuleContents _) _ = panic "filterAvail"
711 subNames :: NameEnv [Name] -> Name -> [Name]
712 subNames env n = lookupNameEnv env n `orElse` []
714 mkSubNameEnv :: NameSet -> NameEnv [Name]
715 -- Maps types and classes to their constructors/classops respectively
716 -- This mapping just makes it easier to deal with A(..) export items
718 = foldNameSet add_name emptyNameEnv names
721 | Just parent <- nameParent_maybe name
722 = extendNameEnv_C (\ns _ -> name:ns) env parent [name]
725 -------------------------------
726 inScopeUnqual :: GlobalRdrEnv -> Name -> Bool
727 -- Checks whether the Name is in scope unqualified,
728 -- regardless of whether it's ambiguous or not
729 inScopeUnqual env n = any unQualOK (lookupGRE_Name env n)
731 -------------------------------
732 checkForDodgyExport :: IE Name -> [Name] -> RnM ()
733 checkForDodgyExport ie@(IEThingAll tc) [n]
734 | isTcOcc (nameOccName n) = addWarn (dodgyExportWarn tc)
735 -- This occurs when you export T(..), but
736 -- only import T abstractly, or T is a synonym.
737 -- The single [n] is the type or class itself
738 | otherwise = addErr (exportItemErr ie)
739 -- This happes if you export x(..), which is bogus
740 checkForDodgyExport _ _ = return ()
742 -------------------------------
743 check_occs :: IE Name -> ExportOccMap -> [Name] -> RnM ExportOccMap
744 check_occs ie occs names
745 = foldlM check occs names
748 = case lookupOccEnv occs name_occ of
749 Nothing -> returnM (extendOccEnv occs name_occ (name, ie))
752 | name == name' -- Duplicate export
753 -> do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
754 warnIf warn_dup_exports (dupExportWarn name_occ ie ie') ;
757 | otherwise -- Same occ name but different names: an error
758 -> do { global_env <- getGlobalRdrEnv ;
759 addErr (exportClashErr global_env name name' ie ie') ;
762 name_occ = nameOccName name
765 %*********************************************************
769 %*********************************************************
772 reportDeprecations :: TcGblEnv -> RnM ()
773 reportDeprecations tcg_env
774 = ifOptM Opt_WarnDeprecations $
775 do { (eps,hpt) <- getEpsAndHpt
776 -- By this time, typechecking is complete,
777 -- so the PIT is fully populated
778 ; mapM_ (check hpt (eps_PIT eps)) all_gres }
780 used_names = allUses (tcg_dus tcg_env)
781 -- Report on all deprecated uses; hence allUses
782 all_gres = globalRdrEnvElts (tcg_rdr_env tcg_env)
784 check hpt pit (GRE {gre_name = name, gre_prov = Imported (imp_spec:_)})
785 | name `elemNameSet` used_names
786 , Just deprec_txt <- lookupDeprec hpt pit name
787 = setSrcSpan (importSpecLoc imp_spec) $
788 addWarn (sep [ptext SLIT("Deprecated use of") <+>
789 pprNonVarNameSpace (occNameSpace (nameOccName name)) <+>
791 (parens imp_msg) <> colon,
794 name_mod = nameModule name
795 imp_mod = importSpecModule imp_spec
796 imp_msg = ptext SLIT("imported from") <+> ppr imp_mod <> extra
797 extra | imp_mod == name_mod = empty
798 | otherwise = ptext SLIT(", but defined in") <+> ppr name_mod
800 check hpt pit ok_gre = returnM () -- Local, or not used, or not deprectated
801 -- The Imported pattern-match: don't deprecate locally defined names
802 -- For a start, we may be exporting a deprecated thing
803 -- Also we may use a deprecated thing in the defn of another
804 -- deprecated things. We may even use a deprecated thing in
805 -- the defn of a non-deprecated thing, when changing a module's
808 lookupDeprec :: HomePackageTable -> PackageIfaceTable
809 -> Name -> Maybe DeprecTxt
810 lookupDeprec hpt pit n
811 = case lookupIface hpt pit (nameModule n) of
812 Just iface -> mi_dep_fn iface n `seqMaybe` -- Bleat if the thing, *or
813 mi_dep_fn iface (nameParent n) -- its parent*, is deprec'd
815 | isWiredInName n -> Nothing
816 -- We have not necessarily loaded the .hi file for a
817 -- wired-in name (yet), although we *could*.
818 -- And we never deprecate them
820 | otherwise -> pprPanic "lookupDeprec" (ppr n)
821 -- By now all the interfaces should have been loaded
823 gre_is_used :: NameSet -> GlobalRdrElt -> Bool
824 gre_is_used used_names gre = gre_name gre `elemNameSet` used_names
827 %*********************************************************
831 %*********************************************************
834 reportUnusedNames :: Maybe [LIE RdrName] -- Export list
835 -> TcGblEnv -> RnM ()
836 reportUnusedNames export_decls gbl_env
837 = do { traceRn ((text "RUN") <+> (ppr (tcg_dus gbl_env)))
838 ; warnUnusedTopBinds unused_locals
839 ; warnUnusedModules unused_imp_mods
840 ; warnUnusedImports unused_imports
841 ; warnDuplicateImports defined_and_used
842 ; printMinimalImports minimal_imports }
844 used_names, all_used_names :: NameSet
845 used_names = findUses (tcg_dus gbl_env) emptyNameSet
846 -- NB: currently, if f x = g, we only treat 'g' as used if 'f' is used
849 all_used_names = used_names `unionNameSets`
850 mkNameSet (mapCatMaybes nameParent_maybe (nameSetToList used_names))
851 -- A use of C implies a use of T,
852 -- if C was brought into scope by T(..) or T(C)
854 -- Collect the defined names from the in-scope environment
855 defined_names :: [GlobalRdrElt]
856 defined_names = globalRdrEnvElts (tcg_rdr_env gbl_env)
858 -- Note that defined_and_used, defined_but_not_used
859 -- are both [GRE]; that's why we need defined_and_used
860 -- rather than just all_used_names
861 defined_and_used, defined_but_not_used :: [GlobalRdrElt]
862 (defined_and_used, defined_but_not_used)
863 = partition (gre_is_used all_used_names) defined_names
865 -- Filter out the ones that are
866 -- (a) defined in this module, and
867 -- (b) not defined by a 'deriving' clause
868 -- The latter have an Internal Name, so we can filter them out easily
869 unused_locals :: [GlobalRdrElt]
870 unused_locals = filter is_unused_local defined_but_not_used
871 is_unused_local :: GlobalRdrElt -> Bool
872 is_unused_local gre = isLocalGRE gre && isExternalName (gre_name gre)
874 unused_imports :: [GlobalRdrElt]
875 unused_imports = filter unused_imp defined_but_not_used
876 unused_imp (GRE {gre_prov = Imported imp_specs})
877 = not (all (module_unused . importSpecModule) imp_specs)
878 && or [exp | ImpSpec { is_item = ImpSome { is_explicit = exp } } <- imp_specs]
879 -- Don't complain about unused imports if we've already said the
880 -- entire import is unused
881 unused_imp other = False
883 -- To figure out the minimal set of imports, start with the things
884 -- that are in scope (i.e. in gbl_env). Then just combine them
885 -- into a bunch of avails, so they are properly grouped
887 -- BUG WARNING: this does not deal properly with qualified imports!
888 minimal_imports :: FiniteMap Module AvailEnv
889 minimal_imports0 = foldr add_expall emptyFM expall_mods
890 minimal_imports1 = foldr add_name minimal_imports0 defined_and_used
891 minimal_imports = foldr add_inst_mod minimal_imports1 direct_import_mods
892 -- The last line makes sure that we retain all direct imports
893 -- even if we import nothing explicitly.
894 -- It's not necessarily redundant to import such modules. Consider
898 -- The import M() is not *necessarily* redundant, even if
899 -- we suck in no instance decls from M (e.g. it contains
900 -- no instance decls, or This contains no code). It may be
901 -- that we import M solely to ensure that M's orphan instance
902 -- decls (or those in its imports) are visible to people who
903 -- import This. Sigh.
904 -- There's really no good way to detect this, so the error message
905 -- in RnEnv.warnUnusedModules is weakened instead
907 -- We've carefully preserved the provenance so that we can
908 -- construct minimal imports that import the name by (one of)
909 -- the same route(s) as the programmer originally did.
910 add_name (GRE {gre_name = n, gre_prov = Imported imp_specs}) acc
911 = addToFM_C plusAvailEnv acc (importSpecModule (head imp_specs))
912 (unitAvailEnv (mk_avail n (nameParent_maybe n)))
916 -- Modules mentioned as 'module M' in the export list
917 expall_mods = case export_decls of
919 Just es -> [m | L _ (IEModuleContents m) <- es]
921 -- This is really bogus. The idea is that if we see 'module M' in
922 -- the export list we must retain the import decls that drive it
923 -- If we aren't careful we might see
924 -- module A( module M ) where
927 -- and suppose that N exports everything that M does. Then we
928 -- must not drop the import of M even though N brings it all into
931 -- BUG WARNING: 'module M' exports aside, what if M.x is mentioned?!
933 -- The reason that add_expall is bogus is that it doesn't take
934 -- qualified imports into account. But it's an improvement.
935 add_expall mod acc = addToFM_C plusAvailEnv acc mod emptyAvailEnv
937 -- n is the name of the thing, p is the name of its parent
938 mk_avail n (Just p) = AvailTC p [p,n]
939 mk_avail n Nothing | isTcOcc (nameOccName n) = AvailTC n [n]
940 | otherwise = Avail n
942 add_inst_mod (mod,_,_) acc
943 | mod `elemFM` acc = acc -- We import something already
944 | otherwise = addToFM acc mod emptyAvailEnv
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,loc) | (mod,no_imp,loc) <- direct_import_mods,
963 not (mod `elemFM` minimal_imports1),
966 -- The not no_imp part is not to complain about
967 -- import M (), which is an idiom for importing
968 -- instance declarations
970 module_unused :: Module -> Bool
971 module_unused mod = any (((==) mod) . fst) unused_imp_mods
973 ---------------------
974 warnDuplicateImports :: [GlobalRdrElt] -> RnM ()
975 -- Given the GREs for names that are used, figure out which imports
976 -- could be omitted without changing the top-level environment.
978 -- NB: Given import Foo( T )
979 -- import qualified Foo
980 -- we do not report a duplicate import, even though Foo.T is brought
981 -- into scope by both, because there's nothing you can *omit* without
982 -- changing the top-level environment. So we complain only if it's
983 -- explicitly named in both imports or neither.
985 -- Furthermore, we complain about Foo.T only if
986 -- there is no complaint about (unqualified) T
988 warnDuplicateImports gres
989 = ifOptM Opt_WarnUnusedImports $
990 sequenceM_ [ warn name pr
991 -- The 'head' picks the first offending group
992 -- for this particular name
993 | GRE { gre_name = name, gre_prov = Imported imps } <- gres
994 , pr <- redundants imps ]
996 warn name (red_imp, cov_imp)
997 = addWarnAt (importSpecLoc red_imp)
998 (vcat [ptext SLIT("Redundant import of:") <+> quotes pp_name,
999 ptext SLIT("It is also") <+> ppr cov_imp])
1001 pp_name | is_qual red_decl = ppr (is_as red_decl) <> dot <> ppr occ
1002 | otherwise = ppr occ
1003 occ = nameOccName name
1004 red_decl = is_decl red_imp
1006 redundants :: [ImportSpec] -> [(ImportSpec,ImportSpec)]
1007 -- The returned pair is (redundant-import, covering-import)
1009 = [ (red_imp, cov_imp)
1011 , cov_imp <- take 1 (filter (covers red_imp) imps) ]
1013 -- "red_imp" is a putative redundant import
1014 -- "cov_imp" potentially covers it
1015 -- This test decides whether red_imp could be dropped
1017 -- NOTE: currently the test does not warn about
1020 -- even if the same underlying 'x' is involved, because dropping
1021 -- either import would change the qualified names in scope (M.x, N.x)
1022 -- But if the qualified names aren't used, the import is indeed redundant
1023 -- Sadly we don't know that. Oh well.
1024 covers red_imp@(ImpSpec { is_decl = red_decl, is_item = red_item })
1025 cov_imp@(ImpSpec { is_decl = cov_decl, is_item = cov_item })
1026 | red_loc == cov_loc
1027 = False -- Ignore diagonal elements
1028 | not (is_as red_decl == is_as cov_decl)
1029 = False -- They bring into scope different qualified names
1030 | not (is_qual red_decl) && is_qual cov_decl
1031 = False -- Covering one doesn't bring unqualified name into scope
1033 = not cov_selective -- Redundant one is selective and covering one isn't
1034 || red_later -- Both are explicit; tie-break using red_later
1036 = not cov_selective -- Neither import is selective
1037 && (is_mod red_decl == is_mod cov_decl) -- They import the same module
1038 && red_later -- Tie-break
1040 red_loc = importSpecLoc red_imp
1041 cov_loc = importSpecLoc cov_imp
1042 red_later = red_loc > cov_loc
1043 cov_selective = selectiveImpItem cov_item
1044 red_selective = selectiveImpItem red_item
1046 selectiveImpItem :: ImpItemSpec -> Bool
1047 selectiveImpItem ImpAll = False
1048 selectiveImpItem (ImpSome {}) = True
1050 -- ToDo: deal with original imports with 'qualified' and 'as M' clauses
1051 printMinimalImports :: FiniteMap Module AvailEnv -- Minimal imports
1053 printMinimalImports imps
1054 = ifOptM Opt_D_dump_minimal_imports $ do {
1056 mod_ies <- mappM to_ies (fmToList imps) ;
1057 this_mod <- getModule ;
1058 rdr_env <- getGlobalRdrEnv ;
1059 ioToTcRn (do { h <- openFile (mkFilename this_mod) WriteMode ;
1060 printForUser h (unQualInScope rdr_env)
1061 (vcat (map ppr_mod_ie mod_ies)) })
1064 mkFilename this_mod = moduleString this_mod ++ ".imports"
1065 ppr_mod_ie (mod_name, ies)
1066 | mod_name == pRELUDE
1068 | null ies -- Nothing except instances comes from here
1069 = ptext SLIT("import") <+> ppr mod_name <> ptext SLIT("() -- Instances only")
1071 = ptext SLIT("import") <+> ppr mod_name <>
1072 parens (fsep (punctuate comma (map ppr ies)))
1074 to_ies (mod, avail_env) = do ies <- mapM to_ie (availEnvElts avail_env)
1077 to_ie :: AvailInfo -> RnM (IE Name)
1078 -- The main trick here is that if we're importing all the constructors
1079 -- we want to say "T(..)", but if we're importing only a subset we want
1080 -- to say "T(A,B,C)". So we have to find out what the module exports.
1081 to_ie (Avail n) = returnM (IEVar n)
1082 to_ie (AvailTC n [m]) = ASSERT( n==m )
1083 returnM (IEThingAbs n)
1084 to_ie (AvailTC n ns)
1085 = loadSrcInterface doc n_mod False `thenM` \ iface ->
1086 case [xs | (m,as) <- mi_exports iface,
1089 x == nameOccName n] of
1090 [xs] | all_used xs -> returnM (IEThingAll n)
1091 | otherwise -> returnM (IEThingWith n (filter (/= n) ns))
1092 other -> pprTrace "to_ie" (ppr n <+> ppr n_mod <+> ppr other) $
1095 all_used avail_occs = all (`elem` map nameOccName ns) avail_occs
1096 doc = text "Compute minimal imports from" <+> ppr n
1097 n_mod = nameModule n
1101 %************************************************************************
1105 %************************************************************************
1108 badImportItemErr iface decl_spec ie
1109 = sep [ptext SLIT("Module"), quotes (ppr (is_mod decl_spec)), source_import,
1110 ptext SLIT("does not export"), quotes (ppr ie)]
1112 source_import | mi_boot iface = ptext SLIT("(hi-boot interface)")
1115 dodgyImportWarn item = dodgyMsg (ptext SLIT("import")) item
1116 dodgyExportWarn item = dodgyMsg (ptext SLIT("export")) item
1119 = sep [ ptext SLIT("The") <+> kind <+> ptext SLIT("item") <+> quotes (ppr (IEThingAll tc)),
1120 ptext SLIT("suggests that") <+> quotes (ppr tc) <+> ptext SLIT("has constructor or class methods"),
1121 ptext SLIT("but it has none; it is a type synonym or abstract type or class") ]
1124 = hsep [ ptext SLIT("Unknown module in export list: module"), quotes (ppr mod)]
1126 exportItemErr export_item
1127 = sep [ ptext SLIT("The export item") <+> quotes (ppr export_item),
1128 ptext SLIT("attempts to export constructors or class methods that are not visible here") ]
1130 exportClashErr global_env name1 name2 ie1 ie2
1131 = vcat [ ptext SLIT("Conflicting exports for") <+> quotes (ppr occ) <> colon
1132 , ppr_export ie1 name1
1133 , ppr_export ie2 name2 ]
1135 occ = nameOccName name1
1136 ppr_export ie name = nest 2 (quotes (ppr ie) <+> ptext SLIT("exports") <+>
1137 quotes (ppr name) <+> pprNameProvenance (get_gre name))
1139 -- get_gre finds a GRE for the Name, so that we can show its provenance
1141 = case lookupGRE_Name global_env name of
1143 [] -> pprPanic "exportClashErr" (ppr name)
1145 addDupDeclErr :: Name -> Name -> TcRn ()
1146 addDupDeclErr name_a name_b
1147 = addErrAt (srcLocSpan loc2) $
1148 vcat [ptext SLIT("Multiple declarations of") <+> quotes (ppr name1),
1149 ptext SLIT("Declared at:") <+> vcat [ppr (nameSrcLoc name1), ppr loc2]]
1151 loc2 = nameSrcLoc name2
1152 (name1,name2) | nameSrcLoc name_a > nameSrcLoc name_b = (name_b,name_a)
1153 | otherwise = (name_a,name_b)
1154 -- Report the error at the later location
1156 dupExportWarn occ_name ie1 ie2
1157 = hsep [quotes (ppr occ_name),
1158 ptext SLIT("is exported by"), quotes (ppr ie1),
1159 ptext SLIT("and"), quotes (ppr ie2)]
1162 = hsep [ptext SLIT("Duplicate"),
1163 quotes (ptext SLIT("Module") <+> ppr mod),
1164 ptext SLIT("in export list")]
1166 moduleDeprec mod txt
1167 = sep [ ptext SLIT("Module") <+> quotes (ppr mod) <+> ptext SLIT("is deprecated:"),