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
12 #include "HsVersions.h"
14 import {-# SOURCE #-} RnHiFiles ( loadInterface )
16 import CmdLineOpts ( DynFlag(..) )
18 import HsSyn ( IE(..), ieName, ImportDecl(..),
19 ForeignDecl(..), HsGroup(..),
20 collectLocatedHsBinders, tyClDeclNames
22 import RdrHsSyn ( RdrNameIE, RdrNameImportDecl )
27 import PrelNames ( pRELUDE_Name, mAIN_Name, isBuiltInSyntaxName )
28 import Module ( Module, ModuleName, ModuleEnv, moduleName,
29 moduleNameUserString, isHomeModule,
30 emptyModuleEnv, unitModuleEnvByName, unitModuleEnv,
31 lookupModuleEnvByName, extendModuleEnvByName, moduleEnvElts )
32 import Name ( Name, nameSrcLoc, nameOccName, nameModule, isExternalName )
35 import OccName ( OccName, dataName, isTcOcc )
36 import HscTypes ( Provenance(..), ImportReason(..), GlobalRdrEnv,
37 GenAvailInfo(..), AvailInfo, Avails,
39 availName, availNames, availsToNameSet,
40 Deprecations(..), ModIface(..), Dependencies(..),
41 GlobalRdrElt(..), unQualInScope, isLocalGRE, pprNameProvenance
43 import RdrName ( RdrName, rdrNameOcc, setRdrNameSpace, lookupRdrEnv,
44 emptyRdrEnv, foldRdrEnv, rdrEnvElts, mkRdrUnqual, isQual )
46 import Maybe ( isJust, isNothing, catMaybes )
47 import ListSetOps ( removeDups )
48 import Util ( sortLt, notNull )
49 import List ( partition, insert )
50 import IO ( openFile, IOMode(..) )
55 %************************************************************************
59 %************************************************************************
62 rnImports :: [RdrNameImportDecl]
63 -> TcRn m (GlobalRdrEnv, ImportAvails)
66 = -- PROCESS IMPORT DECLS
67 -- Do the non {- SOURCE -} ones first, so that we get a helpful
68 -- warning for {- SOURCE -} ones that are unnecessary
69 getModule `thenM` \ this_mod ->
70 getSrcLocM `thenM` \ loc ->
71 doptM Opt_NoImplicitPrelude `thenM` \ opt_no_prelude ->
73 all_imports = mk_prel_imports this_mod loc opt_no_prelude ++ imports
74 (source, ordinary) = partition is_source_import all_imports
75 is_source_import (ImportDecl _ is_boot _ _ _ _) = is_boot
77 get_imports = importsFromImportDecl this_mod
79 mappM get_imports ordinary `thenM` \ stuff1 ->
80 mappM get_imports source `thenM` \ stuff2 ->
84 (imp_gbl_envs, imp_avails) = unzip (stuff1 ++ stuff2)
85 gbl_env :: GlobalRdrEnv
86 gbl_env = foldr plusGlobalRdrEnv emptyRdrEnv imp_gbl_envs
88 all_avails :: ImportAvails
89 all_avails = foldr plusImportAvails emptyImportAvails imp_avails
92 returnM (gbl_env, all_avails)
94 -- NB: opt_NoImplicitPrelude is slightly different to import Prelude ();
95 -- because the former doesn't even look at Prelude.hi for instance
96 -- declarations, whereas the latter does.
97 mk_prel_imports this_mod loc no_prelude
98 | moduleName this_mod == pRELUDE_Name
99 || explicit_prelude_import
103 | otherwise = [preludeImportDecl loc]
105 explicit_prelude_import
106 = notNull [ () | (ImportDecl mod _ _ _ _ _) <- imports,
107 mod == pRELUDE_Name ]
109 preludeImportDecl loc
110 = ImportDecl pRELUDE_Name
111 False {- Not a boot interface -}
112 False {- Not qualified -}
113 Nothing {- No "as" -}
114 Nothing {- No import list -}
119 importsFromImportDecl :: Module
121 -> TcRn m (GlobalRdrEnv, ImportAvails)
123 importsFromImportDecl this_mod
124 (ImportDecl imp_mod_name is_boot qual_only as_mod imp_spec iloc)
127 doc = ppr imp_mod_name <+> ptext SLIT("is directly imported")
130 -- If there's an error in loadInterface, (e.g. interface
131 -- file not found) we get lots of spurious errors from 'filterImports'
132 tryM (loadInterface doc imp_mod_name (ImportByUser is_boot)) `thenM` \ mb_iface ->
135 Left exn -> returnM (emptyRdrEnv, emptyImportAvails ) ;
139 imp_mod = mi_module iface
140 avails_by_module = mi_exports iface
141 deprecs = mi_deprecs iface
142 is_orph = mi_orphan iface
146 avails = [ avail | (mod_name, avails) <- avails_by_module,
147 mod_name /= this_mod_name,
149 this_mod_name = moduleName this_mod
150 -- If the module exports anything defined in this module, just ignore it.
151 -- Reason: otherwise it looks as if there are two local definition sites
152 -- for the thing, and an error gets reported. Easiest thing is just to
153 -- filter them out up front. This situation only arises if a module
154 -- imports itself, or another module that imported it. (Necessarily,
155 -- this invoves a loop.)
157 -- Tiresome consequence: if you say
162 -- module B( AType ) where
163 -- import {-# SOURCE #-} A( AType )
165 -- then you'll get a 'B does not export AType' message. Oh well.
168 -- Filter the imports according to the import list
169 filterImports imp_mod is_boot imp_spec avails `thenM` \ (filtered_avails, explicits) ->
172 -- Compute new transitive dependencies
173 orphans | is_orph = insert imp_mod_name (dep_orphs deps)
174 | otherwise = dep_orphs deps
176 (dependent_mods, dependent_pkgs)
177 | isHomeModule imp_mod
178 = -- Imported module is from the home package
179 -- Take its dependent modules and
180 -- (a) remove this_mod (might be there as a hi-boot)
181 -- (b) add imp_mod itself
182 -- Take its dependent packages unchanged
183 ((imp_mod_name, is_boot) : filter not_self (dep_mods deps), dep_pkgs deps)
186 = -- Imported module is from another package
187 -- Dump the dependent modules
188 -- Add the package imp_mod comes from to the dependent packages
190 ([], insert (mi_package iface) (dep_pkgs deps))
192 not_self (m, _) = m /= this_mod_name
194 import_all = case imp_spec of
195 (Just (False, _)) -> False -- Imports are spec'd explicitly
196 other -> True -- Everything is imported,
197 -- (or almost everything [hiding])
199 qual_mod_name = case as_mod of
200 Nothing -> imp_mod_name
201 Just another_name -> another_name
203 -- unqual_avails is the Avails that are visible in *unqualified* form
204 -- We need to know this so we know what to export when we see
205 -- module M ( module P ) where ...
206 -- Then we must export whatever came from P unqualified.
207 avail_env = mkAvailEnv filtered_avails
209 mk_prov name = NonLocalDef (UserImport imp_mod iloc (name `elemNameSet` explicits))
210 gbl_env = mkGlobalRdrEnv qual_mod_name (not qual_only)
211 mk_prov filtered_avails deprecs
212 imports = ImportAvails {
213 imp_qual = unitModuleEnvByName qual_mod_name avail_env,
215 imp_mods = unitModuleEnv imp_mod (imp_mod, import_all),
217 imp_dep_mods = mkModDeps dependent_mods,
218 imp_dep_pkgs = dependent_pkgs }
221 -- Complain if we import a deprecated module
222 ifOptM Opt_WarnDeprecations (
224 DeprecAll txt -> addWarn (moduleDeprec imp_mod_name txt)
228 returnM (gbl_env, imports)
231 mkModDeps :: [(ModuleName, IsBootInterface)]
232 -> ModuleEnv (ModuleName, IsBootInterface)
233 mkModDeps deps = foldl add emptyModuleEnv deps
235 add env elt@(m,_) = extendModuleEnvByName env m elt
239 %************************************************************************
241 importsFromLocalDecls
243 %************************************************************************
245 From the top-level declarations of this module produce
246 * the lexical environment
248 created by its bindings.
250 Complain about duplicate bindings
253 importsFromLocalDecls :: HsGroup RdrName
254 -> TcRn m (GlobalRdrEnv, ImportAvails)
255 importsFromLocalDecls group
256 = getModule `thenM` \ this_mod ->
257 getLocalDeclBinders this_mod group `thenM` \ avails ->
258 -- The avails that are returned don't include the "system" names
260 all_names :: [Name] -- All the defns; no dups eliminated
261 all_names = [name | avail <- avails, name <- availNames avail]
264 (_, dups) = removeDups compare all_names
266 -- Check for duplicate definitions
267 -- The complaint will come out as "Multiple declarations of Foo.f" because
268 -- since 'f' is in the env twice, the unQualInScope used by the error-msg
269 -- printer returns False. It seems awkward to fix, unfortunately.
270 mappM_ (addErr . dupDeclErr) dups `thenM_`
272 doptM Opt_NoImplicitPrelude `thenM` \ implicit_prelude ->
274 mod_name = moduleName this_mod
275 mk_prov n = LocalDef -- Provenance is local
277 unqual_imp = True -- Want unqualified names in scope
278 gbl_env = mkGlobalRdrEnv mod_name unqual_imp mk_prov avails NoDeprecs
279 -- NoDeprecs: don't complain about locally defined names
280 -- For a start, we may be exporting a deprecated thing
281 -- Also we may use a deprecated thing in the defn of another
282 -- deprecated things. We may even use a deprecated thing in
283 -- the defn of a non-deprecated thing, when changing a module's
287 -- Optimisation: filter out names for built-in syntax
288 -- They just clutter up the environment (esp tuples), and the parser
289 -- will generate Exact RdrNames for them, so the cluttered
290 -- envt is no use. To avoid doing this filter all the time,
291 -- we use -fno-implicit-prelude as a clue that the filter is
292 -- worth while. Really, it's only useful for GHC.Base and GHC.Tuple.
294 -- It's worth doing because it makes the environment smaller for
295 -- every module that imports the Prelude
297 -- Note: don't filter the gbl_env (hence avails, not avails' in
298 -- defn of gbl_env above). Stupid reason: when parsing
299 -- data type decls, the constructors start as Exact tycon-names,
300 -- and then get turned into data con names by zapping the name space;
301 -- but that stops them being Exact, so they get looked up. Sigh.
302 -- It doesn't matter because it only affects the Data.Tuple really.
303 -- The important thing is to trim down the exports.
305 avails' | implicit_prelude = filter not_built_in_syntax avails
307 not_built_in_syntax a = not (all isBuiltInSyntaxName (availNames a))
308 -- Only filter it if all the names of the avail are built-in
309 -- In particular, lists have (:) which is not built in syntax
310 -- so we don't filter it out.
312 avail_env = mkAvailEnv avails'
313 imports = emptyImportAvails {
314 imp_qual = unitModuleEnv this_mod avail_env,
318 returnM (gbl_env, imports)
322 %*********************************************************
324 \subsection{Getting binders out of a declaration}
326 %*********************************************************
328 @getLocalDeclBinders@ returns the names for a @RdrNameHsDecl@. It's
329 used for both source code (from @importsFromLocalDecls@) and interface
330 files (@loadDecl@ calls @getTyClDeclBinders@).
332 *** See "THE NAMING STORY" in HsDecls ****
335 getLocalDeclBinders :: Module -> HsGroup RdrName -> TcRn m [AvailInfo]
336 getLocalDeclBinders mod (HsGroup {hs_valds = val_decls,
337 hs_tyclds = tycl_decls,
338 hs_fords = foreign_decls })
339 = -- For type and class decls, we generate Global names, with
340 -- no export indicator. They need to be global because they get
341 -- permanently bound into the TyCons and Classes. They don't need
342 -- an export indicator because they are all implicitly exported.
344 mappM new_tc tycl_decls `thenM` \ tc_avails ->
345 mappM new_bndr (for_hs_bndrs ++ val_hs_bndrs) `thenM` \ simple_bndrs ->
347 returnM (tc_avails ++ map Avail simple_bndrs)
349 new_bndr (rdr_name,loc) = newTopBinder mod rdr_name loc
351 val_hs_bndrs = collectLocatedHsBinders val_decls
352 for_hs_bndrs = [(nm,loc) | ForeignImport nm _ _ _ loc <- foreign_decls]
354 new_tc tc_decl = mappM new_bndr (tyClDeclNames tc_decl) `thenM` \ names@(main_name:_) ->
355 returnM (AvailTC main_name names)
359 %************************************************************************
361 \subsection{Filtering imports}
363 %************************************************************************
365 @filterImports@ takes the @ExportEnv@ telling what the imported module makes
366 available, and filters it through the import spec (if any).
369 filterImports :: Module -- The module being imported
370 -> IsBootInterface -- Tells whether it's a {-# SOURCE #-} import
371 -> Maybe (Bool, [RdrNameIE]) -- Import spec; True => hiding
372 -> [AvailInfo] -- What's available
373 -> TcRn m ([AvailInfo], -- What's imported
374 NameSet) -- What was imported explicitly
376 -- Complains if import spec mentions things that the module doesn't export
377 -- Warns/informs if import spec contains duplicates.
378 filterImports mod from Nothing imports
379 = returnM (imports, emptyNameSet)
381 filterImports mod from (Just (want_hiding, import_items)) total_avails
382 = mappM get_item import_items `thenM` \ avails_w_explicits_s ->
384 (item_avails, explicits_s) = unzip (concat avails_w_explicits_s)
385 explicits = foldl addListToNameSet emptyNameSet explicits_s
388 let -- All imported; item_avails to be hidden
389 hidden = availsToNameSet item_avails
390 keep n = not (n `elemNameSet` hidden)
392 returnM (pruneAvails keep total_avails, emptyNameSet)
394 -- Just item_avails imported; nothing to be hidden
395 returnM (item_avails, explicits)
397 import_fm :: FiniteMap OccName AvailInfo
398 import_fm = listToFM [ (nameOccName name, avail)
399 | avail <- total_avails,
400 name <- availNames avail]
401 -- Even though availNames returns data constructors too,
402 -- they won't make any difference because naked entities like T
403 -- in an import list map to TcOccs, not VarOccs.
405 bale_out item = addErr (badImportItemErr mod from item) `thenM_`
408 get_item :: RdrNameIE -> TcRn m [(AvailInfo, [Name])]
409 -- Empty list for a bad item.
410 -- Singleton is typical case.
411 -- Can have two when we are hiding, and mention C which might be
412 -- both a class and a data constructor.
413 -- The [Name] is the list of explicitly-mentioned names
414 get_item item@(IEModuleContents _) = bale_out item
416 get_item item@(IEThingAll _)
417 = case check_item item of
418 Nothing -> bale_out item
419 Just avail@(AvailTC _ [n]) -> -- This occurs when you import T(..), but
420 -- only export T abstractly. The single [n]
421 -- in the AvailTC is the type or class itself
422 ifOptM Opt_WarnMisc (addWarn (dodgyImportWarn mod item)) `thenM_`
423 returnM [(avail, [availName avail])]
424 Just avail -> returnM [(avail, [availName avail])]
426 get_item item@(IEThingAbs n)
427 | want_hiding -- hiding( C )
428 -- Here the 'C' can be a data constructor *or* a type/class
429 = case catMaybes [check_item item, check_item (IEVar data_n)] of
431 avails -> returnM [(a, []) | a <- avails]
432 -- The 'explicits' list is irrelevant when hiding
434 data_n = setRdrNameSpace n dataName
437 = case check_item item of
438 Nothing -> bale_out item
439 Just avail -> returnM [(avail, availNames avail)]
442 | isNothing maybe_in_import_avails ||
443 isNothing maybe_filtered_avail
447 = Just filtered_avail
450 wanted_occ = rdrNameOcc (ieName item)
451 maybe_in_import_avails = lookupFM import_fm wanted_occ
453 Just avail = maybe_in_import_avails
454 maybe_filtered_avail = filterAvail item avail
455 Just filtered_avail = maybe_filtered_avail
459 filterAvail :: RdrNameIE -- Wanted
460 -> AvailInfo -- Available
461 -> Maybe AvailInfo -- Resulting available;
462 -- Nothing if (any of the) wanted stuff isn't there
464 filterAvail ie@(IEThingWith want wants) avail@(AvailTC n ns)
465 | sub_names_ok = Just (AvailTC n (filter is_wanted ns))
466 | otherwise = Nothing
468 is_wanted name = nameOccName name `elem` wanted_occs
469 sub_names_ok = all (`elem` avail_occs) wanted_occs
470 avail_occs = map nameOccName ns
471 wanted_occs = map rdrNameOcc (want:wants)
473 filterAvail (IEThingAbs _) (AvailTC n ns) = ASSERT( n `elem` ns )
476 filterAvail (IEThingAbs _) avail@(Avail n) = Just avail -- Type synonyms
478 filterAvail (IEVar _) avail@(Avail n) = Just avail
479 filterAvail (IEVar v) avail@(AvailTC n ns) = Just (AvailTC n (filter wanted ns))
481 wanted n = nameOccName n == occ
483 -- The second equation happens if we import a class op, thus
485 -- where op is a class operation
487 filterAvail (IEThingAll _) avail@(AvailTC _ _) = Just avail
488 -- We don't complain even if the IE says T(..), but
489 -- no constrs/class ops of T are available
490 -- Instead that's caught with a warning by the caller
492 filterAvail ie avail = Nothing
496 %************************************************************************
498 \subsection{Export list processing}
500 %************************************************************************
502 Processing the export list.
504 You might think that we should record things that appear in the export
505 list as ``occurrences'' (using @addOccurrenceName@), but you'd be
506 wrong. We do check (here) that they are in scope, but there is no
507 need to slurp in their actual declaration (which is what
508 @addOccurrenceName@ forces).
510 Indeed, doing so would big trouble when compiling @PrelBase@, because
511 it re-exports @GHC@, which includes @takeMVar#@, whose type includes
512 @ConcBase.StateAndSynchVar#@, and so on...
515 type ExportAccum -- The type of the accumulating parameter of
516 -- the main worker function in exportsFromAvail
517 = ([ModuleName], -- 'module M's seen so far
518 ExportOccMap, -- Tracks exported occurrence names
519 AvailEnv) -- The accumulated exported stuff, kept in an env
520 -- so we can common-up related AvailInfos
521 emptyExportAccum = ([], emptyFM, emptyAvailEnv)
523 type ExportOccMap = FiniteMap OccName (Name, RdrNameIE)
524 -- Tracks what a particular exported OccName
525 -- in an export list refers to, and which item
526 -- it came from. It's illegal to export two distinct things
527 -- that have the same occurrence name
530 exportsFromAvail :: Maybe [RdrNameIE] -> TcRn m Avails
531 -- Complains if two distinct exports have same OccName
532 -- Warns about identical exports.
533 -- Complains about exports items not in scope
534 exportsFromAvail Nothing
535 = do { this_mod <- getModule ;
536 if moduleName this_mod == mAIN_Name then
538 -- Export nothing; Main.$main is automatically exported
540 exportsFromAvail (Just [IEModuleContents (moduleName this_mod)])
541 -- but for all other modules export everything.
544 exportsFromAvail (Just exports)
545 = do { TcGblEnv { tcg_imports = imports } <- getGblEnv ;
546 exports_from_avail exports imports }
548 exports_from_avail export_items
549 (ImportAvails { imp_qual = mod_avail_env,
550 imp_env = entity_avail_env })
551 = foldlM exports_from_item emptyExportAccum
552 export_items `thenM` \ (_, _, export_avail_map) ->
553 returnM (nameEnvElts export_avail_map)
556 exports_from_item :: ExportAccum -> RdrNameIE -> TcRn m ExportAccum
558 exports_from_item acc@(mods, occs, avails) ie@(IEModuleContents mod)
559 | mod `elem` mods -- Duplicate export of M
560 = do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
561 warnIf warn_dup_exports (dupModuleExport mod) ;
565 = case lookupModuleEnvByName mod_avail_env mod of
566 Nothing -> addErr (modExportErr mod) `thenM_`
570 -> getGlobalRdrEnv `thenM` \ global_env ->
572 mod_avails = [ filtered_avail
573 | avail <- availEnvElts avail_env,
574 let mb_avail = filter_unqual global_env avail,
576 let Just filtered_avail = mb_avail]
578 avails' = foldl addAvail avails mod_avails
580 -- This check_occs not only finds conflicts between this item
581 -- and others, but also internally within this item. That is,
582 -- if 'M.x' is in scope in several ways, we'll have several
583 -- members of mod_avails with the same OccName.
585 foldlM (check_occs ie) occs mod_avails `thenM` \ occs' ->
586 returnM (mod:mods, occs', avails')
588 exports_from_item acc@(mods, occs, avails) ie
589 = lookupGRE (ieName ie) `thenM` \ mb_gre ->
591 Nothing -> addErr (unknownNameErr (ieName ie)) `thenM_`
595 -- Get the AvailInfo for the parent of the specified name
596 case lookupAvailEnv entity_avail_env (gre_parent gre) of {
597 Nothing -> pprPanic "exportsFromAvail"
598 ((ppr (ieName ie)) <+> ppr gre) ;
601 -- Filter out the bits we want
602 case filterAvail ie avail of {
603 Nothing -> -- Not enough availability
604 addErr (exportItemErr ie) `thenM_`
609 -- Phew! It's OK! Now to check the occurrence stuff!
610 warnIf (not (ok_item ie avail)) (dodgyExportWarn ie) `thenM_`
611 check_occs ie occs export_avail `thenM` \ occs' ->
612 returnM (mods, occs', addAvail avails export_avail)
616 -------------------------------
617 filter_unqual :: GlobalRdrEnv -> AvailInfo -> Maybe AvailInfo
618 -- Filter the Avail by what's in scope unqualified
619 filter_unqual env (Avail n)
620 | in_scope env n = Just (Avail n)
621 | otherwise = Nothing
622 filter_unqual env (AvailTC n ns)
623 | not (null ns') = Just (AvailTC n ns')
624 | otherwise = Nothing
626 ns' = filter (in_scope env) ns
628 in_scope :: GlobalRdrEnv -> Name -> Bool
629 -- Checks whether the Name is in scope unqualified,
630 -- regardless of whether it's ambiguous or not
632 = case lookupRdrEnv env (mkRdrUnqual (nameOccName n)) of
634 Just gres -> or [n == gre_name g | g <- gres]
637 -------------------------------
638 ok_item (IEThingAll _) (AvailTC _ [n]) = False
639 -- This occurs when you import T(..), but
640 -- only export T abstractly. The single [n]
641 -- in the AvailTC is the type or class itself
644 -------------------------------
645 check_occs :: RdrNameIE -> ExportOccMap -> AvailInfo -> TcRn m ExportOccMap
646 check_occs ie occs avail
647 = foldlM check occs (availNames avail)
650 = case lookupFM occs name_occ of
651 Nothing -> returnM (addToFM occs name_occ (name, ie))
654 | name == name' -- Duplicate export
655 -> do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
656 warnIf warn_dup_exports (dupExportWarn name_occ ie ie') ;
659 | otherwise -- Same occ name but different names: an error
660 -> do { global_env <- getGlobalRdrEnv ;
661 addErr (exportClashErr global_env name name' ie ie') ;
664 name_occ = nameOccName name
667 %*********************************************************
669 \subsection{Unused names}
671 %*********************************************************
674 reportUnusedNames :: TcGblEnv
675 -> NameSet -- Used in this module
677 reportUnusedNames gbl_env used_names
678 = warnUnusedModules unused_imp_mods `thenM_`
679 warnUnusedTopBinds bad_locals `thenM_`
680 warnUnusedImports bad_imports `thenM_`
681 printMinimalImports minimal_imports
683 direct_import_mods :: [ModuleName]
684 direct_import_mods = map (moduleName . fst)
685 (moduleEnvElts (imp_mods (tcg_imports gbl_env)))
687 -- Now, a use of C implies a use of T,
688 -- if C was brought into scope by T(..) or T(C)
689 really_used_names :: NameSet
690 really_used_names = used_names `unionNameSets`
691 mkNameSet [ gre_parent gre
692 | gre <- defined_names,
693 gre_name gre `elemNameSet` used_names]
695 -- Collect the defined names from the in-scope environment
696 -- Look for the qualified ones only, else get duplicates
697 defined_names :: [GlobalRdrElt]
698 defined_names = foldRdrEnv add [] (tcg_rdr_env gbl_env)
699 add rdr_name ns acc | isQual rdr_name = ns ++ acc
702 defined_and_used, defined_but_not_used :: [GlobalRdrElt]
703 (defined_and_used, defined_but_not_used) = partition used defined_names
704 used gre = gre_name gre `elemNameSet` really_used_names
706 -- Filter out the ones that are
707 -- (a) defined in this module, and
708 -- (b) not defined by a 'deriving' clause
709 -- The latter have an Internal Name, so we can filter them out easily
710 bad_locals :: [GlobalRdrElt]
711 bad_locals = filter is_bad defined_but_not_used
713 is_bad :: GlobalRdrElt -> Bool
714 is_bad gre = isLocalGRE gre && isExternalName (gre_name gre)
716 bad_imports :: [GlobalRdrElt]
717 bad_imports = filter bad_imp defined_but_not_used
718 bad_imp (GRE {gre_prov = NonLocalDef (UserImport mod _ True)}) = not (module_unused mod)
719 bad_imp other = False
721 -- To figure out the minimal set of imports, start with the things
722 -- that are in scope (i.e. in gbl_env). Then just combine them
723 -- into a bunch of avails, so they are properly grouped
724 minimal_imports :: FiniteMap ModuleName AvailEnv
725 minimal_imports0 = emptyFM
726 minimal_imports1 = foldr add_name minimal_imports0 defined_and_used
727 minimal_imports = foldr add_inst_mod minimal_imports1 direct_import_mods
728 -- The last line makes sure that we retain all direct imports
729 -- even if we import nothing explicitly.
730 -- It's not necessarily redundant to import such modules. Consider
734 -- The import M() is not *necessarily* redundant, even if
735 -- we suck in no instance decls from M (e.g. it contains
736 -- no instance decls, or This contains no code). It may be
737 -- that we import M solely to ensure that M's orphan instance
738 -- decls (or those in its imports) are visible to people who
739 -- import This. Sigh.
740 -- There's really no good way to detect this, so the error message
741 -- in RnEnv.warnUnusedModules is weakened instead
744 -- We've carefully preserved the provenance so that we can
745 -- construct minimal imports that import the name by (one of)
746 -- the same route(s) as the programmer originally did.
747 add_name (GRE {gre_name = n, gre_parent = p,
748 gre_prov = NonLocalDef (UserImport m _ _)}) acc
749 = addToFM_C plusAvailEnv acc (moduleName m)
750 (unitAvailEnv (mk_avail n p))
754 -- n is the name of the thing, p is the name of its parent
755 mk_avail n p | n/=p = AvailTC p [p,n]
756 | isTcOcc (nameOccName p) = AvailTC n [n]
757 | otherwise = Avail n
760 | m `elemFM` acc = acc -- We import something already
761 | otherwise = addToFM acc m emptyAvailEnv
762 -- Add an empty collection of imports for a module
763 -- from which we have sucked only instance decls
765 -- unused_imp_mods are the directly-imported modules
766 -- that are not mentioned in minimal_imports1
767 -- [Note: not 'minimal_imports', because that includes direcly-imported
768 -- modules even if we use nothing from them; see notes above]
769 unused_imp_mods = [m | m <- direct_import_mods,
770 isNothing (lookupFM minimal_imports1 m),
773 module_unused :: Module -> Bool
774 module_unused mod = moduleName mod `elem` unused_imp_mods
777 -- ToDo: deal with original imports with 'qualified' and 'as M' clauses
778 printMinimalImports :: FiniteMap ModuleName AvailEnv -- Minimal imports
780 printMinimalImports imps
781 = ifOptM Opt_D_dump_minimal_imports $ do {
783 mod_ies <- mappM to_ies (fmToList imps) ;
784 this_mod <- getModule ;
785 rdr_env <- getGlobalRdrEnv ;
786 ioToTcRn (do { h <- openFile (mkFilename this_mod) WriteMode ;
787 printForUser h (unQualInScope rdr_env)
788 (vcat (map ppr_mod_ie mod_ies)) })
791 mkFilename this_mod = moduleNameUserString (moduleName this_mod) ++ ".imports"
792 ppr_mod_ie (mod_name, ies)
793 | mod_name == pRELUDE_Name
795 | null ies -- Nothing except instances comes from here
796 = ptext SLIT("import") <+> ppr mod_name <> ptext SLIT("() -- Instances only")
798 = ptext SLIT("import") <+> ppr mod_name <>
799 parens (fsep (punctuate comma (map ppr ies)))
801 to_ies (mod, avail_env) = mappM to_ie (availEnvElts avail_env) `thenM` \ ies ->
804 to_ie :: AvailInfo -> TcRn m (IE Name)
805 -- The main trick here is that if we're importing all the constructors
806 -- we want to say "T(..)", but if we're importing only a subset we want
807 -- to say "T(A,B,C)". So we have to find out what the module exports.
808 to_ie (Avail n) = returnM (IEVar n)
809 to_ie (AvailTC n [m]) = ASSERT( n==m )
810 returnM (IEThingAbs n)
812 = loadInterface (text "Compute minimal imports from" <+> ppr n_mod)
813 n_mod ImportBySystem `thenM` \ iface ->
814 case [xs | (m,as) <- mi_exports iface,
818 [xs] | all (`elem` ns) xs -> returnM (IEThingAll n)
819 | otherwise -> returnM (IEThingWith n (filter (/= n) ns))
820 other -> pprTrace "to_ie" (ppr n <+> ppr (nameModule n) <+> ppr other) $
823 n_mod = moduleName (nameModule n)
827 %************************************************************************
831 %************************************************************************
834 badImportItemErr mod from ie
835 = sep [ptext SLIT("Module"), quotes (ppr mod), source_import,
836 ptext SLIT("does not export"), quotes (ppr ie)]
838 source_import = case from of
839 True -> ptext SLIT("(hi-boot interface)")
842 dodgyImportWarn mod item = dodgyMsg (ptext SLIT("import")) item
843 dodgyExportWarn item = dodgyMsg (ptext SLIT("export")) item
845 dodgyMsg kind item@(IEThingAll tc)
846 = sep [ ptext SLIT("The") <+> kind <+> ptext SLIT("item") <+> quotes (ppr item),
847 ptext SLIT("suggests that") <+> quotes (ppr tc) <+> ptext SLIT("has constructor or class methods"),
848 ptext SLIT("but it has none; it is a type synonym or abstract type or class") ]
851 = hsep [ ptext SLIT("Unknown module in export list: module"), quotes (ppr mod)]
853 exportItemErr export_item
854 = sep [ ptext SLIT("The export item") <+> quotes (ppr export_item),
855 ptext SLIT("attempts to export constructors or class methods that are not visible here") ]
857 exportClashErr global_env name1 name2 ie1 ie2
858 = vcat [ ptext SLIT("Conflicting exports for") <+> quotes (ppr occ) <> colon
859 , ppr_export ie1 name1
860 , ppr_export ie2 name2 ]
862 occ = nameOccName name1
863 ppr_export ie name = nest 2 (quotes (ppr ie) <+> ptext SLIT("exports") <+>
864 quotes (ppr name) <+> pprNameProvenance (get_gre name))
866 -- get_gre finds a GRE for the Name, in a very inefficient way
867 -- There isn't a more efficient way to do it, because we don't necessarily
868 -- know the RdrName under which this Name is in scope. So we just
869 -- search linearly. Shouldn't matter because this only happens
870 -- in an error message.
872 = case [gre | gres <- rdrEnvElts global_env,
874 gre_name gre == name] of
876 [] -> pprPanic "exportClashErr" (ppr name)
879 = vcat [ptext SLIT("Multiple declarations of") <+> quotes (ppr n),
880 nest 4 (vcat (map ppr sorted_locs))]
882 sorted_locs = sortLt occ'ed_before (map nameSrcLoc (n:ns))
883 occ'ed_before a b = LT == compare a b
885 dupExportWarn occ_name ie1 ie2
886 = hsep [quotes (ppr occ_name),
887 ptext SLIT("is exported by"), quotes (ppr ie1),
888 ptext SLIT("and"), quotes (ppr ie2)]
891 = hsep [ptext SLIT("Duplicate"),
892 quotes (ptext SLIT("Module") <+> ppr mod),
893 ptext SLIT("in export list")]
896 = sep [ ptext SLIT("Module") <+> quotes (ppr mod) <+> ptext SLIT("is deprecated:"),