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(..),
16 ForeignDecl(..), HsGroup(..),
17 collectLocatedHsBinders, tyClDeclNames
19 import RdrHsSyn ( RdrNameIE, RdrNameImportDecl, main_RDR_Unqual )
21 import IfaceEnv ( lookupOrig, lookupImplicitOrig )
22 import LoadIface ( loadSrcInterface )
26 import PrelNames ( pRELUDE_Name, isBuiltInSyntaxName, isUnboundName )
27 import Module ( Module, ModuleName, moduleName,
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 )
36 import HscTypes ( GenAvailInfo(..), AvailInfo, Avails, GhciMode(..),
37 IsBootInterface, IfaceExport,
38 availName, availNames, availsToNameSet, unQualInScope,
39 Deprecs(..), ModIface(..), Dependencies(..)
41 import RdrName ( RdrName, rdrNameOcc, setRdrNameSpace,
42 GlobalRdrEnv, mkGlobalRdrEnv, GlobalRdrElt(..),
43 emptyGlobalRdrEnv, plusGlobalRdrEnv, globalRdrEnvElts,
44 unQualOK, lookupGRE_Name,
45 Provenance(..), ImportSpec(..),
46 isLocalGRE, pprNameProvenance )
48 import Maybes ( isJust, isNothing, catMaybes, mapCatMaybes )
49 import ListSetOps ( removeDups )
50 import Util ( sortLt, notNull )
51 import List ( partition, insert )
52 import IO ( openFile, IOMode(..) )
57 %************************************************************************
61 %************************************************************************
64 rnImports :: [RdrNameImportDecl]
65 -> RnM (GlobalRdrEnv, ImportAvails)
68 = -- PROCESS IMPORT DECLS
69 -- Do the non {- SOURCE -} ones first, so that we get a helpful
70 -- warning for {- SOURCE -} ones that are unnecessary
71 getModule `thenM` \ this_mod ->
72 getSrcLocM `thenM` \ loc ->
73 doptM Opt_NoImplicitPrelude `thenM` \ opt_no_prelude ->
75 all_imports = mk_prel_imports this_mod loc opt_no_prelude ++ imports
76 (source, ordinary) = partition is_source_import all_imports
77 is_source_import (ImportDecl _ is_boot _ _ _ _) = is_boot
79 get_imports = importsFromImportDecl this_mod
81 mappM get_imports ordinary `thenM` \ stuff1 ->
82 mappM get_imports source `thenM` \ stuff2 ->
86 (imp_gbl_envs, imp_avails) = unzip (stuff1 ++ stuff2)
87 gbl_env :: GlobalRdrEnv
88 gbl_env = foldr plusGlobalRdrEnv emptyGlobalRdrEnv imp_gbl_envs
90 all_avails :: ImportAvails
91 all_avails = foldr plusImportAvails emptyImportAvails imp_avails
94 returnM (gbl_env, all_avails)
96 -- NB: opt_NoImplicitPrelude is slightly different to import Prelude ();
97 -- because the former doesn't even look at Prelude.hi for instance
98 -- declarations, whereas the latter does.
99 mk_prel_imports this_mod loc no_prelude
100 | moduleName this_mod == pRELUDE_Name
101 || explicit_prelude_import
105 | otherwise = [preludeImportDecl loc]
107 explicit_prelude_import
108 = notNull [ () | (ImportDecl mod _ _ _ _ _) <- imports,
109 mod == pRELUDE_Name ]
111 preludeImportDecl loc
112 = ImportDecl pRELUDE_Name
113 False {- Not a boot interface -}
114 False {- Not qualified -}
115 Nothing {- No "as" -}
116 Nothing {- No import list -}
121 importsFromImportDecl :: Module
123 -> RnM (GlobalRdrEnv, ImportAvails)
125 importsFromImportDecl this_mod
126 (ImportDecl imp_mod_name want_boot qual_only as_mod imp_details iloc)
129 -- If there's an error in loadInterface, (e.g. interface
130 -- file not found) we get lots of spurious errors from 'filterImports'
132 this_mod_name = moduleName this_mod
133 doc = ppr imp_mod_name <+> ptext SLIT("is directly imported")
135 loadSrcInterface doc imp_mod_name want_boot `thenM` \ iface ->
137 -- Compiler sanity check: if the import didn't say
138 -- {-# SOURCE #-} we should not get a hi-boot file
139 WARN( not want_boot && mi_boot iface, ppr imp_mod_name )
141 -- Issue a user warning for a redundant {- SOURCE -} import
142 -- NB that we arrange to read all the ordinary imports before
143 -- any of the {- SOURCE -} imports
144 warnIf (want_boot && not (mi_boot iface))
145 (warnRedundantSourceImport imp_mod_name) `thenM_`
148 imp_mod = mi_module iface
149 deprecs = mi_deprecs iface
150 is_orph = mi_orphan iface
153 filtered_exports = filter not_this_mod (mi_exports iface)
154 not_this_mod (mod,_) = mod /= this_mod_name
155 -- If the module exports anything defined in this module, just ignore it.
156 -- Reason: otherwise it looks as if there are two local definition sites
157 -- for the thing, and an error gets reported. Easiest thing is just to
158 -- filter them out up front. This situation only arises if a module
159 -- imports itself, or another module that imported it. (Necessarily,
160 -- this invoves a loop.)
162 -- Tiresome consequence: if you say
167 -- module B( AType ) where
168 -- import {-# SOURCE #-} A( AType )
170 -- then you'll get a 'B does not export AType' message. Oh well.
172 exportsToAvails filtered_exports `thenM` \ avails ->
174 -- Filter the imports according to the import list
175 filterImports imp_mod want_boot imp_details avails `thenM` \ (filtered_avails, explicits) ->
178 -- Compute new transitive dependencies
179 orphans | is_orph = insert imp_mod_name (dep_orphs deps)
180 | otherwise = dep_orphs deps
182 (dependent_mods, dependent_pkgs)
183 | isHomeModule imp_mod
184 = -- Imported module is from the home package
185 -- Take its dependent modules and
186 -- (a) remove this_mod (might be there as a hi-boot)
187 -- (b) add imp_mod itself
188 -- Take its dependent packages unchanged
189 ((imp_mod_name, want_boot) : filter not_self (dep_mods deps), dep_pkgs deps)
192 = -- Imported module is from another package
193 -- Dump the dependent modules
194 -- Add the package imp_mod comes from to the dependent packages
196 ([], insert (mi_package iface) (dep_pkgs deps))
198 not_self (m, _) = m /= this_mod_name
200 import_all = case imp_details of
201 Just (is_hiding, ls) -- Imports are spec'd explicitly
202 | not is_hiding -> Just (not (null ls))
203 _ -> Nothing -- Everything is imported,
204 -- (or almost everything [hiding])
206 qual_mod_name = case as_mod of
207 Nothing -> imp_mod_name
208 Just another_name -> another_name
210 -- unqual_avails is the Avails that are visible in *unqualified* form
211 -- We need to know this so we know what to export when we see
212 -- module M ( module P ) where ...
213 -- Then we must export whatever came from P unqualified.
214 imp_spec = ImportSpec { is_mod = imp_mod_name, is_qual = qual_only,
215 is_loc = iloc , is_as = qual_mod_name }
216 mk_deprec = mi_dep_fn iface
217 gres = [ GRE { gre_name = name,
218 gre_prov = Imported [imp_spec] (name `elemNameSet` explicits),
219 gre_deprec = mk_deprec name }
220 | avail <- filtered_avails, name <- availNames avail ]
221 gbl_env = mkGlobalRdrEnv gres
223 avail_env = mkAvailEnv filtered_avails
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 (Avail n) = do { n' <- lookupOrig mod n;
249 ; return (Avail n') }
250 do_avail mod (AvailTC n ns) = do { n' <- lookupOrig mod n
251 ; ns' <- mappM (lookupImplicitOrig n') ns
252 ; return (AvailTC n' ns') }
253 -- Note the lookupImplicitOrig. It ensures that the subordinate names
254 -- record their parent; and that in turn ensures that the GlobalRdrEnv
255 -- has the correct parent for all the names in its range.
256 -- For imported things, we only suck in the binding site later, if ever.
258 warnRedundantSourceImport mod_name
259 = ptext SLIT("Unnecessary {- SOURCE -} in the import of module")
260 <+> quotes (ppr mod_name)
264 %************************************************************************
266 importsFromLocalDecls
268 %************************************************************************
270 From the top-level declarations of this module produce
271 * the lexical environment
273 created by its bindings.
275 Complain about duplicate bindings
278 importsFromLocalDecls :: HsGroup RdrName
279 -> RnM (GlobalRdrEnv, ImportAvails)
280 importsFromLocalDecls group
281 = getModule `thenM` \ this_mod ->
282 getLocalDeclBinders this_mod group `thenM` \ avails ->
283 -- The avails that are returned don't include the "system" names
285 all_names :: [Name] -- All the defns; no dups eliminated
286 all_names = [name | avail <- avails, name <- availNames avail]
289 (_, dups) = removeDups compare all_names
291 -- Check for duplicate definitions
292 -- The complaint will come out as "Multiple declarations of Foo.f" because
293 -- since 'f' is in the env twice, the unQualInScope used by the error-msg
294 -- printer returns False. It seems awkward to fix, unfortunately.
295 mappM_ (addErr . dupDeclErr) dups `thenM_`
297 doptM Opt_NoImplicitPrelude `thenM` \ implicit_prelude ->
299 mod_name = moduleName this_mod
300 prov = LocalDef mod_name
301 gbl_env = mkGlobalRdrEnv gres
302 gres = [ GRE { gre_name = name, gre_prov = prov, gre_deprec = Nothing}
304 -- gre_deprecs = Nothing: don't deprecate locally defined names
305 -- For a start, we may be exporting a deprecated thing
306 -- Also we may use a deprecated thing in the defn of another
307 -- deprecated things. We may even use a deprecated thing in
308 -- the defn of a non-deprecated thing, when changing a module's
312 -- Optimisation: filter out names for built-in syntax
313 -- They just clutter up the environment (esp tuples), and the parser
314 -- will generate Exact RdrNames for them, so the cluttered
315 -- envt is no use. To avoid doing this filter all the time,
316 -- we use -fno-implicit-prelude as a clue that the filter is
317 -- worth while. Really, it's only useful for GHC.Base and GHC.Tuple.
319 -- It's worth doing because it makes the environment smaller for
320 -- every module that imports the Prelude
322 -- Note: don't filter the gbl_env (hence avails, not avails' in
323 -- defn of gbl_env above). Stupid reason: when parsing
324 -- data type decls, the constructors start as Exact tycon-names,
325 -- and then get turned into data con names by zapping the name space;
326 -- but that stops them being Exact, so they get looked up.
327 -- Ditto in fixity decls; e.g. infix 5 :
328 -- Sigh. It doesn't matter because it only affects the Data.Tuple really.
329 -- The important thing is to trim down the exports.
331 avails' | implicit_prelude = filter not_built_in_syntax avails
333 not_built_in_syntax a = not (all isBuiltInSyntaxName (availNames a))
334 -- Only filter it if all the names of the avail are built-in
335 -- In particular, lists have (:) which is not built in syntax
336 -- so we don't filter it out. [Sept 03: wrong: see isBuiltInSyntaxName]
338 avail_env = mkAvailEnv avails'
339 imports = emptyImportAvails {
340 imp_qual = unitModuleEnv this_mod avail_env,
344 returnM (gbl_env, imports)
348 %*********************************************************
350 \subsection{Getting binders out of a declaration}
352 %*********************************************************
354 @getLocalDeclBinders@ returns the names for a @RdrNameHsDecl@. It's
355 used for both source code (from @importsFromLocalDecls@) and interface
356 files (@loadDecl@ calls @getTyClDeclBinders@).
358 *** See "THE NAMING STORY" in HsDecls ****
361 getLocalDeclBinders :: Module -> HsGroup RdrName -> RnM [AvailInfo]
362 getLocalDeclBinders mod (HsGroup {hs_valds = val_decls,
363 hs_tyclds = tycl_decls,
364 hs_fords = foreign_decls })
365 = -- For type and class decls, we generate Global names, with
366 -- no export indicator. They need to be global because they get
367 -- permanently bound into the TyCons and Classes. They don't need
368 -- an export indicator because they are all implicitly exported.
370 mappM new_tc tycl_decls `thenM` \ tc_avails ->
371 mappM new_simple (for_hs_bndrs ++ val_hs_bndrs) `thenM` \ simple_avails ->
372 returnM (tc_avails ++ simple_avails)
374 new_simple rdr_name = newTopSrcBinder mod Nothing rdr_name `thenM` \ name ->
377 val_hs_bndrs = collectLocatedHsBinders val_decls
378 for_hs_bndrs = [(nm,loc) | ForeignImport nm _ _ _ loc <- foreign_decls]
381 = newTopSrcBinder mod Nothing main_rdr `thenM` \ main_name ->
382 mappM (newTopSrcBinder mod (Just main_name)) sub_rdrs `thenM` \ sub_names ->
383 returnM (AvailTC main_name (main_name : sub_names))
385 (main_rdr : sub_rdrs) = tyClDeclNames tc_decl
389 %************************************************************************
391 \subsection{Filtering imports}
393 %************************************************************************
395 @filterImports@ takes the @ExportEnv@ telling what the imported module makes
396 available, and filters it through the import spec (if any).
399 filterImports :: Module -- The module being imported
400 -> IsBootInterface -- Tells whether it's a {-# SOURCE #-} import
401 -> Maybe (Bool, [RdrNameIE]) -- Import spec; True => hiding
402 -> [AvailInfo] -- What's available
403 -> RnM ([AvailInfo], -- What's imported
404 NameSet) -- What was imported explicitly
406 -- Complains if import spec mentions things that the module doesn't export
407 -- Warns/informs if import spec contains duplicates.
408 filterImports mod from Nothing imports
409 = returnM (imports, emptyNameSet)
411 filterImports mod from (Just (want_hiding, import_items)) total_avails
412 = mappM get_item import_items `thenM` \ avails_w_explicits_s ->
414 (item_avails, explicits_s) = unzip (concat avails_w_explicits_s)
415 explicits = foldl addListToNameSet emptyNameSet explicits_s
418 let -- All imported; item_avails to be hidden
419 hidden = availsToNameSet item_avails
420 keep n = not (n `elemNameSet` hidden)
422 returnM (pruneAvails keep total_avails, emptyNameSet)
424 -- Just item_avails imported; nothing to be hidden
425 returnM (item_avails, explicits)
427 import_fm :: FiniteMap OccName AvailInfo
428 import_fm = listToFM [ (nameOccName name, avail)
429 | avail <- total_avails,
430 name <- availNames avail]
431 -- Even though availNames returns data constructors too,
432 -- they won't make any difference because naked entities like T
433 -- in an import list map to TcOccs, not VarOccs.
435 bale_out item = addErr (badImportItemErr mod from item) `thenM_`
438 get_item :: RdrNameIE -> RnM [(AvailInfo, [Name])]
439 -- Empty list for a bad item.
440 -- Singleton is typical case.
441 -- Can have two when we are hiding, and mention C which might be
442 -- both a class and a data constructor.
443 -- The [Name] is the list of explicitly-mentioned names
444 get_item item@(IEModuleContents _) = bale_out item
446 get_item item@(IEThingAll _)
447 = case check_item item of
448 Nothing -> bale_out item
449 Just avail@(AvailTC _ [n]) -> -- This occurs when you import T(..), but
450 -- only export T abstractly. The single [n]
451 -- in the AvailTC is the type or class itself
452 ifOptM Opt_WarnMisc (addWarn (dodgyImportWarn mod item)) `thenM_`
453 returnM [(avail, [availName avail])]
454 Just avail -> returnM [(avail, [availName avail])]
456 get_item item@(IEThingAbs n)
457 | want_hiding -- hiding( C )
458 -- Here the 'C' can be a data constructor *or* a type/class
459 = case catMaybes [check_item item, check_item (IEVar data_n)] of
461 avails -> returnM [(a, []) | a <- avails]
462 -- The 'explicits' list is irrelevant when hiding
464 data_n = setRdrNameSpace n srcDataName
467 = case check_item item of
468 Nothing -> bale_out item
469 Just avail -> returnM [(avail, availNames avail)]
472 | isNothing maybe_in_import_avails ||
473 isNothing maybe_filtered_avail
477 = Just filtered_avail
480 wanted_occ = rdrNameOcc (ieName item)
481 maybe_in_import_avails = lookupFM import_fm wanted_occ
483 Just avail = maybe_in_import_avails
484 maybe_filtered_avail = filterAvail item avail
485 Just filtered_avail = maybe_filtered_avail
489 filterAvail :: RdrNameIE -- Wanted
490 -> AvailInfo -- Available
491 -> Maybe AvailInfo -- Resulting available;
492 -- Nothing if (any of the) wanted stuff isn't there
494 filterAvail ie@(IEThingWith want wants) avail@(AvailTC n ns)
495 | sub_names_ok = Just (AvailTC n (filter is_wanted ns))
496 | otherwise = Nothing
498 is_wanted name = nameOccName name `elem` wanted_occs
499 sub_names_ok = all (`elem` avail_occs) wanted_occs
500 avail_occs = map nameOccName ns
501 wanted_occs = map rdrNameOcc (want:wants)
503 filterAvail (IEThingAbs _) (AvailTC n ns) = ASSERT( n `elem` ns )
506 filterAvail (IEThingAbs _) avail@(Avail n) = Just avail -- Type synonyms
508 filterAvail (IEVar _) avail@(Avail n) = Just avail
509 filterAvail (IEVar v) avail@(AvailTC n ns) = Just (AvailTC n (filter wanted ns))
511 wanted n = nameOccName n == occ
513 -- The second equation happens if we import a class op, thus
515 -- where op is a class operation
517 filterAvail (IEThingAll _) avail@(AvailTC _ _) = Just avail
518 -- We don't complain even if the IE says T(..), but
519 -- no constrs/class ops of T are available
520 -- Instead that's caught with a warning by the caller
522 filterAvail ie avail = Nothing
526 %************************************************************************
528 \subsection{Export list processing}
530 %************************************************************************
532 Processing the export list.
534 You might think that we should record things that appear in the export
535 list as ``occurrences'' (using @addOccurrenceName@), but you'd be
536 wrong. We do check (here) that they are in scope, but there is no
537 need to slurp in their actual declaration (which is what
538 @addOccurrenceName@ forces).
540 Indeed, doing so would big trouble when compiling @PrelBase@, because
541 it re-exports @GHC@, which includes @takeMVar#@, whose type includes
542 @ConcBase.StateAndSynchVar#@, and so on...
545 type ExportAccum -- The type of the accumulating parameter of
546 -- the main worker function in exportsFromAvail
547 = ([ModuleName], -- 'module M's seen so far
548 ExportOccMap, -- Tracks exported occurrence names
549 AvailEnv) -- The accumulated exported stuff, kept in an env
550 -- so we can common-up related AvailInfos
551 emptyExportAccum = ([], emptyFM, emptyAvailEnv)
553 type ExportOccMap = FiniteMap OccName (Name, RdrNameIE)
554 -- Tracks what a particular exported OccName
555 -- in an export list refers to, and which item
556 -- it came from. It's illegal to export two distinct things
557 -- that have the same occurrence name
560 exportsFromAvail :: Maybe Module -- Nothing => no 'module M(..) where' header at all
561 -> Maybe [RdrNameIE] -- Nothing => no explicit export list
563 -- Complains if two distinct exports have same OccName
564 -- Warns about identical exports.
565 -- Complains about exports items not in scope
567 exportsFromAvail maybe_mod exports
568 = do { TcGblEnv { tcg_rdr_env = rdr_env,
569 tcg_imports = imports } <- getGblEnv ;
571 -- If the module header is omitted altogether, then behave
572 -- as if the user had written "module Main(main) where..."
573 -- EXCEPT in interactive mode, when we behave as if he had
574 -- written "module Main where ..."
575 -- Reason: don't want to complain about 'main' not in scope
576 -- in interactive mode
577 ghci_mode <- getGhciMode ;
581 Nothing | ghci_mode == Interactive -> Nothing
582 | otherwise -> Just [IEVar main_RDR_Unqual] } ;
584 exports_from_avail real_exports rdr_env imports }
586 exports_from_avail Nothing rdr_env
587 imports@(ImportAvails { imp_env = entity_avail_env })
588 = -- Export all locally-defined things
589 -- We do this by filtering the global RdrEnv,
590 -- keeping only things that are (a) qualified,
591 -- (b) locally defined, (c) a 'main' name
592 -- Then we look up in the entity-avail-env
593 return [ lookupAvailEnv entity_avail_env name
594 | gre <- globalRdrEnvElts rdr_env,
596 let name = gre_name gre,
597 isNothing (nameParent_maybe name) -- Main things only
600 exports_from_avail (Just export_items) rdr_env
601 (ImportAvails { imp_qual = mod_avail_env,
602 imp_env = entity_avail_env })
603 = foldlM exports_from_item emptyExportAccum
604 export_items `thenM` \ (_, _, export_avail_map) ->
605 returnM (nameEnvElts export_avail_map)
608 exports_from_item :: ExportAccum -> RdrNameIE -> RnM ExportAccum
610 exports_from_item acc@(mods, occs, avails) ie@(IEModuleContents mod)
611 | mod `elem` mods -- Duplicate export of M
612 = do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
613 warnIf warn_dup_exports (dupModuleExport mod) ;
617 = case lookupModuleEnvByName mod_avail_env mod of
618 Nothing -> addErr (modExportErr mod) `thenM_`
623 mod_avails = [ filtered_avail
624 | avail <- availEnvElts avail_env,
625 let mb_avail = filter_unqual rdr_env avail,
627 let Just filtered_avail = mb_avail]
629 avails' = foldl addAvail avails mod_avails
631 -- This check_occs not only finds conflicts between this item
632 -- and others, but also internally within this item. That is,
633 -- if 'M.x' is in scope in several ways, we'll have several
634 -- members of mod_avails with the same OccName.
636 foldlM (check_occs ie) occs mod_avails `thenM` \ occs' ->
637 returnM (mod:mods, occs', avails')
639 exports_from_item acc@(mods, occs, avails) ie
640 = lookupGlobalOccRn (ieName ie) `thenM` \ name ->
641 if isUnboundName name then
642 returnM acc -- Avoid error cascade
644 -- Get the AvailInfo for the parent of the specified name
646 parent = nameParent name
647 avail = lookupAvailEnv entity_avail_env parent
649 -- Filter out the bits we want
650 case filterAvail ie avail of {
651 Nothing -> -- Not enough availability
652 addErr (exportItemErr ie) `thenM_`
657 -- Phew! It's OK! Now to check the occurrence stuff!
658 warnIf (not (ok_item ie avail)) (dodgyExportWarn ie) `thenM_`
659 check_occs ie occs export_avail `thenM` \ occs' ->
660 returnM (mods, occs', addAvail avails export_avail)
664 -------------------------------
665 filter_unqual :: GlobalRdrEnv -> AvailInfo -> Maybe AvailInfo
666 -- Filter the Avail by what's in scope unqualified
667 filter_unqual env (Avail n)
668 | in_scope env n = Just (Avail n)
669 | otherwise = Nothing
670 filter_unqual env (AvailTC n ns)
671 | not (null ns') = Just (AvailTC n ns')
672 | otherwise = Nothing
674 ns' = filter (in_scope env) ns
676 in_scope :: GlobalRdrEnv -> Name -> Bool
677 -- Checks whether the Name is in scope unqualified,
678 -- regardless of whether it's ambiguous or not
679 in_scope env n = any unQualOK (lookupGRE_Name env n)
682 -------------------------------
683 ok_item (IEThingAll _) (AvailTC _ [n]) = False
684 -- This occurs when you import T(..), but
685 -- only export T abstractly. The single [n]
686 -- in the AvailTC is the type or class itself
689 -------------------------------
690 check_occs :: RdrNameIE -> ExportOccMap -> AvailInfo -> RnM ExportOccMap
691 check_occs ie occs avail
692 = foldlM check occs (availNames avail)
695 = case lookupFM occs name_occ of
696 Nothing -> returnM (addToFM occs name_occ (name, ie))
699 | name == name' -- Duplicate export
700 -> do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
701 warnIf warn_dup_exports (dupExportWarn name_occ ie ie') ;
704 | otherwise -- Same occ name but different names: an error
705 -> do { global_env <- getGlobalRdrEnv ;
706 addErr (exportClashErr global_env name name' ie ie') ;
709 name_occ = nameOccName name
712 %*********************************************************
714 \subsection{Unused names}
716 %*********************************************************
719 reportUnusedNames :: TcGblEnv -> RnM ()
720 reportUnusedNames gbl_env
721 = warnUnusedModules unused_imp_mods `thenM_`
722 warnUnusedTopBinds bad_locals `thenM_`
723 warnUnusedImports bad_imports `thenM_`
724 printMinimalImports minimal_imports
726 used_names, all_used_names :: NameSet
727 used_names = findUses (tcg_dus gbl_env) emptyNameSet
728 all_used_names = used_names `unionNameSets`
729 mkNameSet (mapCatMaybes nameParent_maybe (nameSetToList used_names))
730 -- A use of C implies a use of T,
731 -- if C was brought into scope by T(..) or T(C)
733 -- Collect the defined names from the in-scope environment
734 defined_names :: [GlobalRdrElt]
735 defined_names = globalRdrEnvElts (tcg_rdr_env gbl_env)
737 defined_and_used, defined_but_not_used :: [GlobalRdrElt]
738 (defined_and_used, defined_but_not_used) = partition is_used defined_names
740 is_used gre = gre_name gre `elemNameSet` all_used_names
742 -- Filter out the ones that are
743 -- (a) defined in this module, and
744 -- (b) not defined by a 'deriving' clause
745 -- The latter have an Internal Name, so we can filter them out easily
746 bad_locals :: [GlobalRdrElt]
747 bad_locals = filter is_bad defined_but_not_used
748 is_bad :: GlobalRdrElt -> Bool
749 is_bad gre = isLocalGRE gre && isExternalName (gre_name gre)
751 bad_imports :: [GlobalRdrElt]
752 bad_imports = filter bad_imp defined_but_not_used
753 bad_imp (GRE {gre_prov = Imported imp_specs True})
754 = not (all (module_unused . is_mod) imp_specs)
755 -- Don't complain about unused imports if we've already said the
756 -- entire import is unused
757 bad_imp other = False
759 -- To figure out the minimal set of imports, start with the things
760 -- that are in scope (i.e. in gbl_env). Then just combine them
761 -- into a bunch of avails, so they are properly grouped
762 minimal_imports :: FiniteMap ModuleName AvailEnv
763 minimal_imports0 = emptyFM
764 minimal_imports1 = foldr add_name minimal_imports0 defined_and_used
765 minimal_imports = foldr add_inst_mod minimal_imports1 direct_import_mods
766 -- The last line makes sure that we retain all direct imports
767 -- even if we import nothing explicitly.
768 -- It's not necessarily redundant to import such modules. Consider
772 -- The import M() is not *necessarily* redundant, even if
773 -- we suck in no instance decls from M (e.g. it contains
774 -- no instance decls, or This contains no code). It may be
775 -- that we import M solely to ensure that M's orphan instance
776 -- decls (or those in its imports) are visible to people who
777 -- import This. Sigh.
778 -- There's really no good way to detect this, so the error message
779 -- in RnEnv.warnUnusedModules is weakened instead
782 -- We've carefully preserved the provenance so that we can
783 -- construct minimal imports that import the name by (one of)
784 -- the same route(s) as the programmer originally did.
785 add_name (GRE {gre_name = n,
786 gre_prov = Imported imp_specs _}) acc
787 = addToFM_C plusAvailEnv acc (is_mod (head imp_specs))
788 (unitAvailEnv (mk_avail n (nameParent_maybe n)))
792 -- n is the name of the thing, p is the name of its parent
793 mk_avail n (Just p) = AvailTC p [p,n]
794 mk_avail n Nothing | isTcOcc (nameOccName n) = AvailTC n [n]
795 | otherwise = Avail n
798 | m `elemFM` acc = acc -- We import something already
799 | otherwise = addToFM acc m emptyAvailEnv
800 -- Add an empty collection of imports for a module
801 -- from which we have sucked only instance decls
803 imports = tcg_imports gbl_env
805 direct_import_mods :: [ModuleName]
806 direct_import_mods = map (moduleName . fst)
807 (moduleEnvElts (imp_mods imports))
809 hasEmptyImpList :: ModuleName -> Bool
811 case lookupModuleEnvByName (imp_mods imports) m of
812 Just (_,Just x) -> not x
815 -- unused_imp_mods are the directly-imported modules
816 -- that are not mentioned in minimal_imports1
817 -- [Note: not 'minimal_imports', because that includes direcly-imported
818 -- modules even if we use nothing from them; see notes above]
819 unused_imp_mods = [m | m <- direct_import_mods,
820 isNothing (lookupFM minimal_imports1 m),
822 not (hasEmptyImpList m)]
823 -- hasEmptyImpList arranges not to complain about
824 -- import M (), which is an idiom for importing
825 -- instance declarations
827 module_unused :: ModuleName -> Bool
828 module_unused mod = mod `elem` unused_imp_mods
831 -- ToDo: deal with original imports with 'qualified' and 'as M' clauses
832 printMinimalImports :: FiniteMap ModuleName AvailEnv -- Minimal imports
834 printMinimalImports imps
835 = ifOptM Opt_D_dump_minimal_imports $ do {
837 mod_ies <- mappM to_ies (fmToList imps) ;
838 this_mod <- getModule ;
839 rdr_env <- getGlobalRdrEnv ;
840 ioToTcRn (do { h <- openFile (mkFilename this_mod) WriteMode ;
841 printForUser h (unQualInScope rdr_env)
842 (vcat (map ppr_mod_ie mod_ies)) })
845 mkFilename this_mod = moduleNameUserString (moduleName this_mod) ++ ".imports"
846 ppr_mod_ie (mod_name, ies)
847 | mod_name == pRELUDE_Name
849 | null ies -- Nothing except instances comes from here
850 = ptext SLIT("import") <+> ppr mod_name <> ptext SLIT("() -- Instances only")
852 = ptext SLIT("import") <+> ppr mod_name <>
853 parens (fsep (punctuate comma (map ppr ies)))
855 to_ies (mod, avail_env) = mappM to_ie (availEnvElts avail_env) `thenM` \ ies ->
858 to_ie :: AvailInfo -> RnM (IE Name)
859 -- The main trick here is that if we're importing all the constructors
860 -- we want to say "T(..)", but if we're importing only a subset we want
861 -- to say "T(A,B,C)". So we have to find out what the module exports.
862 to_ie (Avail n) = returnM (IEVar n)
863 to_ie (AvailTC n [m]) = ASSERT( n==m )
864 returnM (IEThingAbs n)
866 = loadSrcInterface doc n_mod False `thenM` \ iface ->
867 case [xs | (m,as) <- mi_exports iface,
870 x == nameOccName n] of
871 [xs] | all_used xs -> returnM (IEThingAll n)
872 | otherwise -> returnM (IEThingWith n (filter (/= n) ns))
873 other -> pprTrace "to_ie" (ppr n <+> ppr n_mod <+> ppr other) $
876 all_used avail_occs = all (`elem` map nameOccName ns) avail_occs
877 doc = text "Compute minimal imports from" <+> ppr n
878 n_mod = nameModuleName n
882 %************************************************************************
886 %************************************************************************
889 badImportItemErr mod from ie
890 = sep [ptext SLIT("Module"), quotes (ppr mod), source_import,
891 ptext SLIT("does not export"), quotes (ppr ie)]
893 source_import = case from of
894 True -> ptext SLIT("(hi-boot interface)")
897 dodgyImportWarn mod item = dodgyMsg (ptext SLIT("import")) item
898 dodgyExportWarn item = dodgyMsg (ptext SLIT("export")) item
900 dodgyMsg kind item@(IEThingAll tc)
901 = sep [ ptext SLIT("The") <+> kind <+> ptext SLIT("item") <+> quotes (ppr item),
902 ptext SLIT("suggests that") <+> quotes (ppr tc) <+> ptext SLIT("has constructor or class methods"),
903 ptext SLIT("but it has none; it is a type synonym or abstract type or class") ]
906 = hsep [ ptext SLIT("Unknown module in export list: module"), quotes (ppr mod)]
908 exportItemErr export_item
909 = sep [ ptext SLIT("The export item") <+> quotes (ppr export_item),
910 ptext SLIT("attempts to export constructors or class methods that are not visible here") ]
912 exportClashErr global_env name1 name2 ie1 ie2
913 = vcat [ ptext SLIT("Conflicting exports for") <+> quotes (ppr occ) <> colon
914 , ppr_export ie1 name1
915 , ppr_export ie2 name2 ]
917 occ = nameOccName name1
918 ppr_export ie name = nest 2 (quotes (ppr ie) <+> ptext SLIT("exports") <+>
919 quotes (ppr name) <+> pprNameProvenance (get_gre name))
921 -- get_gre finds a GRE for the Name, so that we can show its provenance
923 = case lookupGRE_Name global_env name of
925 [] -> pprPanic "exportClashErr" (ppr name)
928 = vcat [ptext SLIT("Multiple declarations of") <+> quotes (ppr n),
929 nest 4 (vcat (map ppr sorted_locs))]
931 sorted_locs = sortLt occ'ed_before (map nameSrcLoc (n:ns))
932 occ'ed_before a b = LT == compare a b
934 dupExportWarn occ_name ie1 ie2
935 = hsep [quotes (ppr occ_name),
936 ptext SLIT("is exported by"), quotes (ppr ie1),
937 ptext SLIT("and"), quotes (ppr ie2)]
940 = hsep [ptext SLIT("Duplicate"),
941 quotes (ptext SLIT("Module") <+> ppr mod),
942 ptext SLIT("in export list")]
945 = sep [ ptext SLIT("Module") <+> quotes (ppr mod) <+> ptext SLIT("is deprecated:"),