2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[RnNames]{Extracting imported and top-level names in scope}
8 rnImports, importsFromLocalDecls, exportsFromAvail,
9 reportUnusedNames, mkModDeps, exportsToAvails
12 #include "HsVersions.h"
14 import CmdLineOpts ( DynFlag(..) )
15 import HsSyn ( IE(..), ieName, ImportDecl(..), LImportDecl,
16 ForeignDecl(..), HsGroup(..),
17 collectGroupBinders, tyClDeclNames
20 import IfaceEnv ( lookupOrig, newGlobalBinder )
21 import LoadIface ( loadSrcInterface )
25 import PrelNames ( pRELUDE_Name, isBuiltInSyntaxName, isUnboundName,
27 import Module ( Module, ModuleName, moduleName, mkPackageModule,
28 moduleNameUserString, isHomeModule,
29 unitModuleEnvByName, unitModuleEnv,
30 lookupModuleEnvByName, moduleEnvElts )
31 import Name ( Name, nameSrcLoc, nameOccName, nameModuleName,
32 nameParent, nameParent_maybe, isExternalName )
35 import OccName ( OccName, srcDataName, isTcOcc, OccEnv, elemOccEnv,
36 mkOccEnv, lookupOccEnv, emptyOccEnv, extendOccEnv )
37 import HscTypes ( GenAvailInfo(..), AvailInfo, Avails, GhciMode(..),
38 IsBootInterface, IfaceExport,
39 availName, availNames, availsToNameSet, unQualInScope,
40 Deprecs(..), ModIface(..), Dependencies(..)
42 import RdrName ( RdrName, rdrNameOcc, setRdrNameSpace,
43 GlobalRdrEnv, mkGlobalRdrEnv, GlobalRdrElt(..),
44 emptyGlobalRdrEnv, plusGlobalRdrEnv, globalRdrEnvElts,
45 unQualOK, lookupGRE_Name,
46 Provenance(..), ImportSpec(..),
47 isLocalGRE, pprNameProvenance )
49 import Maybes ( isJust, isNothing, catMaybes, mapCatMaybes )
50 import SrcLoc ( noSrcLoc, Located(..), mkGeneralSrcSpan,
52 import ListSetOps ( removeDups )
53 import Util ( sortLt, notNull, isSingleton )
54 import List ( partition, insert )
55 import IO ( openFile, IOMode(..) )
60 %************************************************************************
64 %************************************************************************
67 rnImports :: [LImportDecl RdrName]
68 -> RnM (GlobalRdrEnv, ImportAvails)
71 = -- PROCESS IMPORT DECLS
72 -- Do the non {- SOURCE -} ones first, so that we get a helpful
73 -- warning for {- SOURCE -} ones that are unnecessary
74 getModule `thenM` \ this_mod ->
75 doptM Opt_NoImplicitPrelude `thenM` \ opt_no_prelude ->
77 all_imports = mk_prel_imports this_mod opt_no_prelude ++ imports
78 (source, ordinary) = partition is_source_import all_imports
79 is_source_import (L _ (ImportDecl _ is_boot _ _ _)) = is_boot
81 get_imports = importsFromImportDecl this_mod
83 mappM get_imports ordinary `thenM` \ stuff1 ->
84 mappM get_imports source `thenM` \ stuff2 ->
88 (imp_gbl_envs, imp_avails) = unzip (stuff1 ++ stuff2)
89 gbl_env :: GlobalRdrEnv
90 gbl_env = foldr plusGlobalRdrEnv emptyGlobalRdrEnv imp_gbl_envs
92 all_avails :: ImportAvails
93 all_avails = foldr plusImportAvails emptyImportAvails imp_avails
96 returnM (gbl_env, all_avails)
98 -- NB: opt_NoImplicitPrelude is slightly different to import Prelude ();
99 -- because the former doesn't even look at Prelude.hi for instance
100 -- declarations, whereas the latter does.
101 mk_prel_imports this_mod no_prelude
102 | moduleName this_mod == pRELUDE_Name
103 || explicit_prelude_import
107 | otherwise = [preludeImportDecl]
109 explicit_prelude_import
110 = notNull [ () | L _ (ImportDecl mod _ _ _ _) <- imports,
111 unLoc mod == pRELUDE_Name ]
115 ImportDecl (L loc pRELUDE_Name)
116 False {- Not a boot interface -}
117 False {- Not qualified -}
118 Nothing {- No "as" -}
119 Nothing {- No import list -}
121 loc = mkGeneralSrcSpan FSLIT("Implicit import declaration")
125 importsFromImportDecl :: Module
126 -> LImportDecl RdrName
127 -> RnM (GlobalRdrEnv, ImportAvails)
129 importsFromImportDecl this_mod
130 (L loc (ImportDecl loc_imp_mod_name want_boot qual_only as_mod imp_details))
134 -- If there's an error in loadInterface, (e.g. interface
135 -- file not found) we get lots of spurious errors from 'filterImports'
137 imp_mod_name = unLoc loc_imp_mod_name
138 this_mod_name = moduleName this_mod
139 doc = ppr imp_mod_name <+> ptext SLIT("is directly imported")
141 loadSrcInterface doc imp_mod_name want_boot `thenM` \ iface ->
143 -- Compiler sanity check: if the import didn't say
144 -- {-# SOURCE #-} we should not get a hi-boot file
145 WARN( not want_boot && mi_boot iface, ppr imp_mod_name )
147 -- Issue a user warning for a redundant {- SOURCE -} import
148 -- NB that we arrange to read all the ordinary imports before
149 -- any of the {- SOURCE -} imports
150 warnIf (want_boot && not (mi_boot iface))
151 (warnRedundantSourceImport imp_mod_name) `thenM_`
154 imp_mod = mi_module iface
155 deprecs = mi_deprecs iface
156 is_orph = mi_orphan iface
159 filtered_exports = filter not_this_mod (mi_exports iface)
160 not_this_mod (mod,_) = mod /= this_mod_name
161 -- If the module exports anything defined in this module, just ignore it.
162 -- Reason: otherwise it looks as if there are two local definition sites
163 -- for the thing, and an error gets reported. Easiest thing is just to
164 -- filter them out up front. This situation only arises if a module
165 -- imports itself, or another module that imported it. (Necessarily,
166 -- this invoves a loop.)
168 -- Tiresome consequence: if you say
173 -- module B( AType ) where
174 -- import {-# SOURCE #-} A( AType )
176 -- then you'll get a 'B does not export AType' message. Oh well.
178 qual_mod_name = case as_mod of
179 Nothing -> imp_mod_name
180 Just another_name -> another_name
181 imp_spec = ImportSpec { is_mod = imp_mod_name, is_qual = qual_only,
182 is_loc = loc, is_as = qual_mod_name }
183 mk_deprec = mi_dep_fn iface
186 -- Get the total imports, and filter them according to the import list
187 exportsToAvails filtered_exports `thenM` \ total_avails ->
188 filterImports iface imp_spec
189 imp_details total_avails `thenM` \ (avail_env, gbl_env) ->
192 -- Compute new transitive dependencies
193 orphans | is_orph = insert imp_mod_name (dep_orphs deps)
194 | otherwise = dep_orphs deps
196 (dependent_mods, dependent_pkgs)
197 | isHomeModule imp_mod
198 = -- Imported module is from the home package
199 -- Take its dependent modules and
200 -- (a) remove this_mod (might be there as a hi-boot)
201 -- (b) add imp_mod itself
202 -- Take its dependent packages unchanged
203 ((imp_mod_name, want_boot) : filter not_self (dep_mods deps), dep_pkgs deps)
206 = -- Imported module is from another package
207 -- Dump the dependent modules
208 -- Add the package imp_mod comes from to the dependent packages
210 ([], insert (mi_package iface) (dep_pkgs deps))
212 not_self (m, _) = m /= this_mod_name
214 import_all = case imp_details of
215 Just (is_hiding, ls) -- Imports are spec'd explicitly
216 | not is_hiding -> Just (not (null ls))
217 _ -> Nothing -- Everything is imported,
218 -- (or almost everything [hiding])
220 -- unqual_avails is the Avails that are visible in *unqualified* form
221 -- We need to know this so we know what to export when we see
222 -- module M ( module P ) where ...
223 -- Then we must export whatever came from P unqualified.
224 imports = ImportAvails {
225 imp_qual = unitModuleEnvByName qual_mod_name avail_env,
227 imp_mods = unitModuleEnv imp_mod (imp_mod, import_all),
229 imp_dep_mods = mkModDeps dependent_mods,
230 imp_dep_pkgs = dependent_pkgs }
233 -- Complain if we import a deprecated module
234 ifOptM Opt_WarnDeprecations (
236 DeprecAll txt -> addWarn (moduleDeprec imp_mod_name txt)
240 returnM (gbl_env, imports)
242 exportsToAvails :: [IfaceExport] -> TcRnIf gbl lcl Avails
243 exportsToAvails exports
244 = do { avails_by_module <- mappM do_one exports
245 ; return (concat avails_by_module) }
247 do_one (mod_name, exports) = mapM (do_avail mod_name) exports
248 do_avail mod_nm (Avail n) = do { n' <- lookupOrig mod_nm n;
249 ; return (Avail n') }
250 do_avail mod_nm (AvailTC n ns) = do { n' <- lookupOrig mod_nm n
251 ; ns' <- mappM (lookup_sub n') ns
252 ; return (AvailTC n' ns') }
254 mod = mkPackageModule mod_nm -- Not necessarily right yet
255 lookup_sub parent occ = newGlobalBinder mod occ (Just parent) noSrcLoc
256 -- Hack alert! Notice the newGlobalBinder. It ensures that the subordinate
257 -- names record their parent; and that in turn ensures that the GlobalRdrEnv
258 -- has the correct parent for all the names in its range.
259 -- For imported things, we only suck in the binding site later, if ever.
260 -- Reason for all this:
261 -- Suppose module M exports type A.T, and constructor A.MkT
262 -- Then, we know that A.MkT is a subordinate name of A.T,
263 -- even though we aren't at the binding site of A.T
264 -- And it's important, because we may simply re-export A.T
265 -- without ever sucking in the declaration itself.
267 warnRedundantSourceImport mod_name
268 = ptext SLIT("Unnecessary {- SOURCE -} in the import of module")
269 <+> quotes (ppr mod_name)
273 %************************************************************************
275 importsFromLocalDecls
277 %************************************************************************
279 From the top-level declarations of this module produce
280 * the lexical environment
282 created by its bindings.
284 Complain about duplicate bindings
287 importsFromLocalDecls :: HsGroup RdrName
288 -> RnM (GlobalRdrEnv, ImportAvails)
289 importsFromLocalDecls group
290 = getModule `thenM` \ this_mod ->
291 getLocalDeclBinders this_mod group `thenM` \ avails ->
292 -- The avails that are returned don't include the "system" names
294 all_names :: [Name] -- All the defns; no dups eliminated
295 all_names = [name | avail <- avails, name <- availNames avail]
298 (_, dups) = removeDups compare all_names
300 -- Check for duplicate definitions
301 -- The complaint will come out as "Multiple declarations of Foo.f" because
302 -- since 'f' is in the env twice, the unQualInScope used by the error-msg
303 -- printer returns False. It seems awkward to fix, unfortunately.
304 mappM_ (addErr . dupDeclErr) dups `thenM_`
306 doptM Opt_NoImplicitPrelude `thenM` \ implicit_prelude ->
308 mod_name = moduleName this_mod
309 prov = LocalDef mod_name
310 gbl_env = mkGlobalRdrEnv gres
311 gres = [ GRE { gre_name = name, gre_prov = prov, gre_deprec = Nothing}
313 -- gre_deprecs = Nothing: don't deprecate locally defined names
314 -- For a start, we may be exporting a deprecated thing
315 -- Also we may use a deprecated thing in the defn of another
316 -- deprecated things. We may even use a deprecated thing in
317 -- the defn of a non-deprecated thing, when changing a module's
321 -- Optimisation: filter out names for built-in syntax
322 -- They just clutter up the environment (esp tuples), and the parser
323 -- will generate Exact RdrNames for them, so the cluttered
324 -- envt is no use. To avoid doing this filter all the time,
325 -- we use -fno-implicit-prelude as a clue that the filter is
326 -- worth while. Really, it's only useful for GHC.Base and GHC.Tuple.
328 -- It's worth doing because it makes the environment smaller for
329 -- every module that imports the Prelude
331 -- Note: don't filter the gbl_env (hence avails, not avails' in
332 -- defn of gbl_env above). Stupid reason: when parsing
333 -- data type decls, the constructors start as Exact tycon-names,
334 -- and then get turned into data con names by zapping the name space;
335 -- but that stops them being Exact, so they get looked up.
336 -- Ditto in fixity decls; e.g. infix 5 :
337 -- Sigh. It doesn't matter because it only affects the Data.Tuple really.
338 -- The important thing is to trim down the exports.
340 avails' | implicit_prelude = filter not_built_in_syntax avails
342 not_built_in_syntax a = not (all isBuiltInSyntaxName (availNames a))
343 -- Only filter it if all the names of the avail are built-in
344 -- In particular, lists have (:) which is not built in syntax
345 -- so we don't filter it out. [Sept 03: wrong: see isBuiltInSyntaxName]
347 avail_env = mkAvailEnv avails'
348 imports = emptyImportAvails {
349 imp_qual = unitModuleEnv this_mod avail_env,
353 returnM (gbl_env, imports)
357 %*********************************************************
359 \subsection{Getting binders out of a declaration}
361 %*********************************************************
363 @getLocalDeclBinders@ returns the names for an @HsDecl@. It's
364 used for source code.
366 *** See "THE NAMING STORY" in HsDecls ****
369 getLocalDeclBinders :: Module -> HsGroup RdrName -> RnM [AvailInfo]
370 getLocalDeclBinders mod (HsGroup {hs_valds = val_decls,
371 hs_tyclds = tycl_decls,
372 hs_fords = foreign_decls })
373 = -- For type and class decls, we generate Global names, with
374 -- no export indicator. They need to be global because they get
375 -- permanently bound into the TyCons and Classes. They don't need
376 -- an export indicator because they are all implicitly exported.
378 mappM new_tc tycl_decls `thenM` \ tc_avails ->
379 mappM new_simple (for_hs_bndrs ++ val_hs_bndrs) `thenM` \ simple_avails ->
380 returnM (tc_avails ++ simple_avails)
382 new_simple rdr_name = newTopSrcBinder mod Nothing rdr_name `thenM` \ name ->
385 val_hs_bndrs = collectGroupBinders val_decls
386 for_hs_bndrs = [nm | L _ (ForeignImport nm _ _ _) <- foreign_decls]
389 = newTopSrcBinder mod Nothing main_rdr `thenM` \ main_name ->
390 mappM (newTopSrcBinder mod (Just main_name)) sub_rdrs `thenM` \ sub_names ->
391 returnM (AvailTC main_name (main_name : sub_names))
393 (main_rdr : sub_rdrs) = tyClDeclNames (unLoc tc_decl)
397 %************************************************************************
399 \subsection{Filtering imports}
401 %************************************************************************
403 @filterImports@ takes the @ExportEnv@ telling what the imported module makes
404 available, and filters it through the import spec (if any).
407 filterImports :: ModIface
408 -> ImportSpec -- The span for the entire import decl
409 -> Maybe (Bool, [Located (IE RdrName)]) -- Import spec; True => hiding
410 -> [AvailInfo] -- What's available
411 -> RnM (AvailEnv, -- What's imported
412 GlobalRdrEnv) -- ...in two forms
414 -- Complains if import spec mentions things that the module doesn't export
415 -- Warns/informs if import spec contains duplicates.
416 mkGenericRdrEnv iface imp_spec avails
417 = mkGlobalRdrEnv [ GRE { gre_name = name, gre_prov = Imported [imp_spec] False,
418 gre_deprec = mi_dep_fn iface name }
419 | avail <- avails, name <- availNames avail ]
421 filterImports iface imp_spec Nothing total_avails
422 = returnM (mkAvailEnv total_avails, mkGenericRdrEnv iface imp_spec total_avails)
424 filterImports iface imp_spec (Just (want_hiding, import_items)) total_avails
425 = mapAndUnzipM (addLocM get_item) import_items `thenM` \ (avails, gres) ->
427 all_avails = foldr plusAvailEnv emptyAvailEnv avails
428 rdr_env = foldr plusGlobalRdrEnv emptyGlobalRdrEnv gres
430 if not want_hiding then
431 returnM (all_avails, rdr_env)
433 let -- Hide stuff in all_avails
434 hidden = availsToNameSet (availEnvElts all_avails)
435 keep n = not (n `elemNameSet` hidden)
436 pruned_avails = pruneAvails keep total_avails
438 returnM (mkAvailEnv pruned_avails, mkGenericRdrEnv iface imp_spec pruned_avails)
440 import_fm :: OccEnv AvailInfo
441 import_fm = mkOccEnv [ (nameOccName name, avail)
442 | avail <- total_avails,
443 name <- availNames avail]
444 -- Even though availNames returns data constructors too,
445 -- they won't make any difference because naked entities like T
446 -- in an import list map to TcOccs, not VarOccs.
448 bale_out item = addErr (badImportItemErr iface imp_spec item) `thenM_`
449 returnM (emptyAvailEnv, emptyGlobalRdrEnv)
451 mk_deprec = mi_dep_fn iface
453 succeed_with :: Bool -> AvailInfo -> RnM (AvailEnv, GlobalRdrEnv)
454 succeed_with all_explicit avail
455 = do { loc <- getSrcSpanM
456 ; returnM (unitAvailEnv avail,
457 mkGlobalRdrEnv (map (mk_gre loc) (availNames avail))) }
459 mk_gre loc name = GRE { gre_name = name,
460 gre_prov = Imported [this_imp_spec loc] (explicit name),
461 gre_deprec = mk_deprec name }
462 this_imp_spec loc = imp_spec { is_loc = loc }
463 explicit name = all_explicit || name == main_name
464 main_name = availName avail
466 get_item :: IE RdrName -> RnM (AvailEnv, GlobalRdrEnv)
467 -- Empty result for a bad item.
468 -- Singleton result is typical case.
469 -- Can have two when we are hiding, and mention C which might be
470 -- both a class and a data constructor.
471 get_item item@(IEModuleContents _)
474 get_item item@(IEThingAll tc)
475 = case check_item item of
476 Nothing -> bale_out item
477 Just avail@(AvailTC _ [n]) -> -- This occurs when you import T(..), but
478 -- only export T abstractly. The single [n]
479 -- in the AvailTC is the type or class itself
480 ifOptM Opt_WarnMisc (addWarn (dodgyImportWarn tc)) `thenM_`
481 succeed_with False avail
482 Just avail -> succeed_with False avail
484 get_item item@(IEThingAbs n)
485 | want_hiding -- hiding( C )
486 -- Here the 'C' can be a data constructor *or* a type/class
487 = case catMaybes [check_item item, check_item (IEVar data_n)] of
489 avails -> returnM (mkAvailEnv avails, emptyGlobalRdrEnv)
490 -- The GlobalRdrEnv result is irrelevant when hiding
492 data_n = setRdrNameSpace n srcDataName
495 = case check_item item of
496 Nothing -> bale_out item
497 Just avail -> succeed_with True avail
500 | isNothing maybe_in_import_avails ||
501 isNothing maybe_filtered_avail
505 = Just filtered_avail
508 wanted_occ = rdrNameOcc (ieName item)
509 maybe_in_import_avails = lookupOccEnv import_fm wanted_occ
511 Just avail = maybe_in_import_avails
512 maybe_filtered_avail = filterAvail item avail
513 Just filtered_avail = maybe_filtered_avail
517 filterAvail :: IE RdrName -- Wanted
518 -> AvailInfo -- Available
519 -> Maybe AvailInfo -- Resulting available;
520 -- Nothing if (any of the) wanted stuff isn't there
522 filterAvail ie@(IEThingWith want wants) avail@(AvailTC n ns)
523 | sub_names_ok = Just (AvailTC n (filter is_wanted ns))
524 | otherwise = Nothing
526 is_wanted name = nameOccName name `elem` wanted_occs
527 sub_names_ok = all (`elem` avail_occs) wanted_occs
528 avail_occs = map nameOccName ns
529 wanted_occs = map rdrNameOcc (want:wants)
531 filterAvail (IEThingAbs _) (AvailTC n ns) = ASSERT( n `elem` ns )
534 filterAvail (IEThingAbs _) avail@(Avail n) = Just avail -- Type synonyms
536 filterAvail (IEVar _) avail@(Avail n) = Just avail
537 filterAvail (IEVar v) avail@(AvailTC n ns) = Just (AvailTC n (filter wanted ns))
539 wanted n = nameOccName n == occ
541 -- The second equation happens if we import a class op, thus
543 -- where op is a class operation
545 filterAvail (IEThingAll _) avail@(AvailTC _ _) = Just avail
546 -- We don't complain even if the IE says T(..), but
547 -- no constrs/class ops of T are available
548 -- Instead that's caught with a warning by the caller
550 filterAvail ie avail = Nothing
554 %************************************************************************
556 \subsection{Export list processing}
558 %************************************************************************
560 Processing the export list.
562 You might think that we should record things that appear in the export
563 list as ``occurrences'' (using @addOccurrenceName@), but you'd be
564 wrong. We do check (here) that they are in scope, but there is no
565 need to slurp in their actual declaration (which is what
566 @addOccurrenceName@ forces).
568 Indeed, doing so would big trouble when compiling @PrelBase@, because
569 it re-exports @GHC@, which includes @takeMVar#@, whose type includes
570 @ConcBase.StateAndSynchVar#@, and so on...
573 type ExportAccum -- The type of the accumulating parameter of
574 -- the main worker function in exportsFromAvail
575 = ([ModuleName], -- 'module M's seen so far
576 ExportOccMap, -- Tracks exported occurrence names
577 AvailEnv) -- The accumulated exported stuff, kept in an env
578 -- so we can common-up related AvailInfos
579 emptyExportAccum = ([], emptyOccEnv, emptyAvailEnv)
581 type ExportOccMap = OccEnv (Name, IE RdrName)
582 -- Tracks what a particular exported OccName
583 -- in an export list refers to, and which item
584 -- it came from. It's illegal to export two distinct things
585 -- that have the same occurrence name
588 exportsFromAvail :: Bool -- False => no 'module M(..) where' header at all
589 -> Maybe [Located (IE RdrName)] -- Nothing => no explicit export list
591 -- Complains if two distinct exports have same OccName
592 -- Warns about identical exports.
593 -- Complains about exports items not in scope
595 exportsFromAvail explicit_mod exports
596 = do { TcGblEnv { tcg_rdr_env = rdr_env,
597 tcg_imports = imports } <- getGblEnv ;
599 -- If the module header is omitted altogether, then behave
600 -- as if the user had written "module Main(main) where..."
601 -- EXCEPT in interactive mode, when we behave as if he had
602 -- written "module Main where ..."
603 -- Reason: don't want to complain about 'main' not in scope
604 -- in interactive mode
605 ghci_mode <- getGhciMode ;
607 | explicit_mod = exports
608 | ghci_mode == Interactive = Nothing
609 | otherwise = Just [noLoc (IEVar main_RDR_Unqual)] } ;
610 exports_from_avail real_exports rdr_env imports }
613 exports_from_avail Nothing rdr_env
614 imports@(ImportAvails { imp_env = entity_avail_env })
615 = -- Export all locally-defined things
616 -- We do this by filtering the global RdrEnv,
617 -- keeping only things that are (a) qualified,
618 -- (b) locally defined, (c) a 'main' name
619 -- Then we look up in the entity-avail-env
620 return [ lookupAvailEnv entity_avail_env name
621 | gre <- globalRdrEnvElts rdr_env,
623 let name = gre_name gre,
624 isNothing (nameParent_maybe name) -- Main things only
627 exports_from_avail (Just export_items) rdr_env
628 (ImportAvails { imp_qual = mod_avail_env,
629 imp_env = entity_avail_env })
630 = foldlM (exports_from_litem) emptyExportAccum
631 export_items `thenM` \ (_, _, export_avail_map) ->
632 returnM (nameEnvElts export_avail_map)
635 exports_from_litem :: ExportAccum -> Located (IE RdrName) -> RnM ExportAccum
636 exports_from_litem acc = addLocM (exports_from_item acc)
638 exports_from_item :: ExportAccum -> IE RdrName -> RnM ExportAccum
639 exports_from_item acc@(mods, occs, avails) ie@(IEModuleContents mod)
640 | mod `elem` mods -- Duplicate export of M
641 = do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
642 warnIf warn_dup_exports (dupModuleExport mod) ;
646 = case lookupModuleEnvByName mod_avail_env mod of
647 Nothing -> addErr (modExportErr mod) `thenM_`
652 mod_avails = [ filtered_avail
653 | avail <- availEnvElts avail_env,
654 let mb_avail = filter_unqual rdr_env avail,
656 let Just filtered_avail = mb_avail]
658 avails' = foldl addAvail avails mod_avails
660 -- This check_occs not only finds conflicts between this item
661 -- and others, but also internally within this item. That is,
662 -- if 'M.x' is in scope in several ways, we'll have several
663 -- members of mod_avails with the same OccName.
665 foldlM (check_occs ie) occs mod_avails `thenM` \ occs' ->
666 returnM (mod:mods, occs', avails')
668 exports_from_item acc@(mods, occs, avails) ie
669 = lookupGlobalOccRn (ieName ie) `thenM` \ name ->
670 if isUnboundName name then
671 returnM acc -- Avoid error cascade
673 -- Get the AvailInfo for the parent of the specified name
675 parent = nameParent name
676 avail = lookupAvailEnv entity_avail_env parent
678 -- Filter out the bits we want
679 case filterAvail ie avail of {
680 Nothing -> -- Not enough availability
681 addErr (exportItemErr ie) `thenM_`
686 -- Phew! It's OK! Now to check the occurrence stuff!
687 checkForDodgyExport ie avail `thenM_`
688 check_occs ie occs export_avail `thenM` \ occs' ->
689 returnM (mods, occs', addAvail avails export_avail)
693 -------------------------------
694 filter_unqual :: GlobalRdrEnv -> AvailInfo -> Maybe AvailInfo
695 -- Filter the Avail by what's in scope unqualified
696 filter_unqual env (Avail n)
697 | in_scope env n = Just (Avail n)
698 | otherwise = Nothing
699 filter_unqual env (AvailTC n ns)
700 | not (null ns') = Just (AvailTC n ns')
701 | otherwise = Nothing
703 ns' = filter (in_scope env) ns
705 in_scope :: GlobalRdrEnv -> Name -> Bool
706 -- Checks whether the Name is in scope unqualified,
707 -- regardless of whether it's ambiguous or not
708 in_scope env n = any unQualOK (lookupGRE_Name env n)
710 -------------------------------
711 checkForDodgyExport :: IE RdrName -> AvailInfo -> RnM ()
712 checkForDodgyExport (IEThingAll tc) (AvailTC _ [n]) = addWarn (dodgyExportWarn tc)
713 -- This occurs when you import T(..), but
714 -- only export T abstractly. The single [n]
715 -- in the AvailTC is the type or class itself
716 checkForDodgyExport _ _ = return ()
718 -------------------------------
719 check_occs :: IE RdrName -> ExportOccMap -> AvailInfo -> RnM ExportOccMap
720 check_occs ie occs avail
721 = foldlM check occs (availNames avail)
724 = case lookupOccEnv occs name_occ of
725 Nothing -> returnM (extendOccEnv occs name_occ (name, ie))
728 | name == name' -- Duplicate export
729 -> do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
730 warnIf warn_dup_exports (dupExportWarn name_occ ie ie') ;
733 | otherwise -- Same occ name but different names: an error
734 -> do { global_env <- getGlobalRdrEnv ;
735 addErr (exportClashErr global_env name name' ie ie') ;
738 name_occ = nameOccName name
741 %*********************************************************
743 \subsection{Unused names}
745 %*********************************************************
748 reportUnusedNames :: TcGblEnv -> RnM ()
749 reportUnusedNames gbl_env
750 = warnUnusedModules unused_imp_mods `thenM_`
751 warnUnusedTopBinds bad_locals `thenM_`
752 warnUnusedImports bad_imports `thenM_`
753 warnDuplicateImports dup_imps `thenM_`
754 printMinimalImports minimal_imports
756 used_names, all_used_names :: NameSet
757 used_names = findUses (tcg_dus gbl_env) emptyNameSet
758 all_used_names = used_names `unionNameSets`
759 mkNameSet (mapCatMaybes nameParent_maybe (nameSetToList used_names))
760 -- A use of C implies a use of T,
761 -- if C was brought into scope by T(..) or T(C)
763 -- Collect the defined names from the in-scope environment
764 defined_names :: [GlobalRdrElt]
765 defined_names = globalRdrEnvElts (tcg_rdr_env gbl_env)
767 defined_and_used, defined_but_not_used :: [GlobalRdrElt]
768 (defined_and_used, defined_but_not_used) = partition is_used defined_names
770 dup_imps = filter isDupImport defined_and_used
771 is_used gre = gre_name gre `elemNameSet` all_used_names
773 -- Filter out the ones that are
774 -- (a) defined in this module, and
775 -- (b) not defined by a 'deriving' clause
776 -- The latter have an Internal Name, so we can filter them out easily
777 bad_locals :: [GlobalRdrElt]
778 bad_locals = filter is_bad defined_but_not_used
779 is_bad :: GlobalRdrElt -> Bool
780 is_bad gre = isLocalGRE gre && isExternalName (gre_name gre)
782 bad_imports :: [GlobalRdrElt]
783 bad_imports = filter bad_imp defined_but_not_used
784 bad_imp (GRE {gre_prov = Imported imp_specs True})
785 = not (all (module_unused . is_mod) imp_specs)
786 -- Don't complain about unused imports if we've already said the
787 -- entire import is unused
788 bad_imp other = False
790 -- To figure out the minimal set of imports, start with the things
791 -- that are in scope (i.e. in gbl_env). Then just combine them
792 -- into a bunch of avails, so they are properly grouped
793 minimal_imports :: FiniteMap ModuleName AvailEnv
794 minimal_imports0 = emptyFM
795 minimal_imports1 = foldr add_name minimal_imports0 defined_and_used
796 minimal_imports = foldr add_inst_mod minimal_imports1 direct_import_mods
797 -- The last line makes sure that we retain all direct imports
798 -- even if we import nothing explicitly.
799 -- It's not necessarily redundant to import such modules. Consider
803 -- The import M() is not *necessarily* redundant, even if
804 -- we suck in no instance decls from M (e.g. it contains
805 -- no instance decls, or This contains no code). It may be
806 -- that we import M solely to ensure that M's orphan instance
807 -- decls (or those in its imports) are visible to people who
808 -- import This. Sigh.
809 -- There's really no good way to detect this, so the error message
810 -- in RnEnv.warnUnusedModules is weakened instead
813 -- We've carefully preserved the provenance so that we can
814 -- construct minimal imports that import the name by (one of)
815 -- the same route(s) as the programmer originally did.
816 add_name (GRE {gre_name = n,
817 gre_prov = Imported imp_specs _}) acc
818 = addToFM_C plusAvailEnv acc (is_mod (head imp_specs))
819 (unitAvailEnv (mk_avail n (nameParent_maybe n)))
823 -- n is the name of the thing, p is the name of its parent
824 mk_avail n (Just p) = AvailTC p [p,n]
825 mk_avail n Nothing | isTcOcc (nameOccName n) = AvailTC n [n]
826 | otherwise = Avail n
829 | m `elemFM` acc = acc -- We import something already
830 | otherwise = addToFM acc m emptyAvailEnv
831 -- Add an empty collection of imports for a module
832 -- from which we have sucked only instance decls
834 imports = tcg_imports gbl_env
836 direct_import_mods :: [ModuleName]
837 direct_import_mods = map (moduleName . fst)
838 (moduleEnvElts (imp_mods imports))
840 hasEmptyImpList :: ModuleName -> Bool
842 case lookupModuleEnvByName (imp_mods imports) m of
843 Just (_,Just x) -> not x
846 -- unused_imp_mods are the directly-imported modules
847 -- that are not mentioned in minimal_imports1
848 -- [Note: not 'minimal_imports', because that includes directly-imported
849 -- modules even if we use nothing from them; see notes above]
850 unused_imp_mods = [m | m <- direct_import_mods,
851 isNothing (lookupFM minimal_imports1 m),
853 not (hasEmptyImpList m)]
854 -- hasEmptyImpList arranges not to complain about
855 -- import M (), which is an idiom for importing
856 -- instance declarations
858 module_unused :: ModuleName -> Bool
859 module_unused mod = mod `elem` unused_imp_mods
862 isDupImport (GRE {gre_prov = Imported imp_spec True}) = not (isSingleton imp_spec)
863 isDupImport other = False
865 warnDuplicateImports :: [GlobalRdrElt] -> RnM ()
866 warnDuplicateImports gres
867 = ifOptM Opt_WarnUnusedImports (mapM_ warn gres)
869 warn (GRE { gre_name = name, gre_prov = Imported imps _ })
870 = addWarn ((quotes (ppr name) <+> ptext SLIT("is imported more than once:"))
871 $$ nest 2 (vcat (map ppr imps)))
874 -- ToDo: deal with original imports with 'qualified' and 'as M' clauses
875 printMinimalImports :: FiniteMap ModuleName AvailEnv -- Minimal imports
877 printMinimalImports imps
878 = ifOptM Opt_D_dump_minimal_imports $ do {
880 mod_ies <- mappM to_ies (fmToList imps) ;
881 this_mod <- getModule ;
882 rdr_env <- getGlobalRdrEnv ;
883 ioToTcRn (do { h <- openFile (mkFilename this_mod) WriteMode ;
884 printForUser h (unQualInScope rdr_env)
885 (vcat (map ppr_mod_ie mod_ies)) })
888 mkFilename this_mod = moduleNameUserString (moduleName this_mod) ++ ".imports"
889 ppr_mod_ie (mod_name, ies)
890 | mod_name == pRELUDE_Name
892 | null ies -- Nothing except instances comes from here
893 = ptext SLIT("import") <+> ppr mod_name <> ptext SLIT("() -- Instances only")
895 = ptext SLIT("import") <+> ppr mod_name <>
896 parens (fsep (punctuate comma (map ppr ies)))
898 to_ies (mod, avail_env) = mappM to_ie (availEnvElts avail_env) `thenM` \ ies ->
901 to_ie :: AvailInfo -> RnM (IE Name)
902 -- The main trick here is that if we're importing all the constructors
903 -- we want to say "T(..)", but if we're importing only a subset we want
904 -- to say "T(A,B,C)". So we have to find out what the module exports.
905 to_ie (Avail n) = returnM (IEVar n)
906 to_ie (AvailTC n [m]) = ASSERT( n==m )
907 returnM (IEThingAbs n)
909 = loadSrcInterface doc n_mod False `thenM` \ iface ->
910 case [xs | (m,as) <- mi_exports iface,
913 x == nameOccName n] of
914 [xs] | all_used xs -> returnM (IEThingAll n)
915 | otherwise -> returnM (IEThingWith n (filter (/= n) ns))
916 other -> pprTrace "to_ie" (ppr n <+> ppr n_mod <+> ppr other) $
919 all_used avail_occs = all (`elem` map nameOccName ns) avail_occs
920 doc = text "Compute minimal imports from" <+> ppr n
921 n_mod = nameModuleName n
925 %************************************************************************
929 %************************************************************************
932 badImportItemErr iface imp_spec ie
933 = sep [ptext SLIT("Module"), quotes (ppr (is_mod imp_spec)), source_import,
934 ptext SLIT("does not export"), quotes (ppr ie)]
936 source_import | mi_boot iface = ptext SLIT("(hi-boot interface)")
939 dodgyImportWarn item = dodgyMsg (ptext SLIT("import")) item
940 dodgyExportWarn item = dodgyMsg (ptext SLIT("export")) item
943 = sep [ ptext SLIT("The") <+> kind <+> ptext SLIT("item") <+> quotes (ppr (IEThingAll tc)),
944 ptext SLIT("suggests that") <+> quotes (ppr tc) <+> ptext SLIT("has constructor or class methods"),
945 ptext SLIT("but it has none; it is a type synonym or abstract type or class") ]
948 = hsep [ ptext SLIT("Unknown module in export list: module"), quotes (ppr mod)]
950 exportItemErr export_item
951 = sep [ ptext SLIT("The export item") <+> quotes (ppr export_item),
952 ptext SLIT("attempts to export constructors or class methods that are not visible here") ]
954 exportClashErr global_env name1 name2 ie1 ie2
955 = vcat [ ptext SLIT("Conflicting exports for") <+> quotes (ppr occ) <> colon
956 , ppr_export ie1 name1
957 , ppr_export ie2 name2 ]
959 occ = nameOccName name1
960 ppr_export ie name = nest 2 (quotes (ppr ie) <+> ptext SLIT("exports") <+>
961 quotes (ppr name) <+> pprNameProvenance (get_gre name))
963 -- get_gre finds a GRE for the Name, so that we can show its provenance
965 = case lookupGRE_Name global_env name of
967 [] -> pprPanic "exportClashErr" (ppr name)
970 = vcat [ptext SLIT("Multiple declarations of") <+> quotes (ppr n),
971 nest 4 (vcat (map ppr sorted_locs))]
973 sorted_locs = sortLt occ'ed_before (map nameSrcLoc (n:ns))
974 occ'ed_before a b = LT == compare a b
976 dupExportWarn occ_name ie1 ie2
977 = hsep [quotes (ppr occ_name),
978 ptext SLIT("is exported by"), quotes (ppr ie1),
979 ptext SLIT("and"), quotes (ppr ie2)]
982 = hsep [ptext SLIT("Duplicate"),
983 quotes (ptext SLIT("Module") <+> ppr mod),
984 ptext SLIT("in export list")]
987 = sep [ ptext SLIT("Module") <+> quotes (ppr mod) <+> ptext SLIT("is deprecated:"),