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, newGlobalBinder )
22 import LoadIface ( loadSrcInterface )
26 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 )
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 SrcLoc ( noSrcLoc )
50 import ListSetOps ( removeDups )
51 import Util ( sortLt, notNull )
52 import List ( partition, insert )
53 import IO ( openFile, IOMode(..) )
58 %************************************************************************
62 %************************************************************************
65 rnImports :: [RdrNameImportDecl]
66 -> RnM (GlobalRdrEnv, ImportAvails)
69 = -- PROCESS IMPORT DECLS
70 -- Do the non {- SOURCE -} ones first, so that we get a helpful
71 -- warning for {- SOURCE -} ones that are unnecessary
72 getModule `thenM` \ this_mod ->
73 getSrcLocM `thenM` \ loc ->
74 doptM Opt_NoImplicitPrelude `thenM` \ opt_no_prelude ->
76 all_imports = mk_prel_imports this_mod loc opt_no_prelude ++ imports
77 (source, ordinary) = partition is_source_import all_imports
78 is_source_import (ImportDecl _ is_boot _ _ _ _) = is_boot
80 get_imports = importsFromImportDecl this_mod
82 mappM get_imports ordinary `thenM` \ stuff1 ->
83 mappM get_imports source `thenM` \ stuff2 ->
87 (imp_gbl_envs, imp_avails) = unzip (stuff1 ++ stuff2)
88 gbl_env :: GlobalRdrEnv
89 gbl_env = foldr plusGlobalRdrEnv emptyGlobalRdrEnv imp_gbl_envs
91 all_avails :: ImportAvails
92 all_avails = foldr plusImportAvails emptyImportAvails imp_avails
95 returnM (gbl_env, all_avails)
97 -- NB: opt_NoImplicitPrelude is slightly different to import Prelude ();
98 -- because the former doesn't even look at Prelude.hi for instance
99 -- declarations, whereas the latter does.
100 mk_prel_imports this_mod loc no_prelude
101 | moduleName this_mod == pRELUDE_Name
102 || explicit_prelude_import
106 | otherwise = [preludeImportDecl loc]
108 explicit_prelude_import
109 = notNull [ () | (ImportDecl mod _ _ _ _ _) <- imports,
110 mod == pRELUDE_Name ]
112 preludeImportDecl loc
113 = ImportDecl pRELUDE_Name
114 False {- Not a boot interface -}
115 False {- Not qualified -}
116 Nothing {- No "as" -}
117 Nothing {- No import list -}
122 importsFromImportDecl :: Module
124 -> RnM (GlobalRdrEnv, ImportAvails)
126 importsFromImportDecl this_mod
127 (ImportDecl imp_mod_name want_boot qual_only as_mod imp_details iloc)
130 -- If there's an error in loadInterface, (e.g. interface
131 -- file not found) we get lots of spurious errors from 'filterImports'
133 this_mod_name = moduleName this_mod
134 doc = ppr imp_mod_name <+> ptext SLIT("is directly imported")
136 loadSrcInterface doc imp_mod_name want_boot `thenM` \ iface ->
138 -- Compiler sanity check: if the import didn't say
139 -- {-# SOURCE #-} we should not get a hi-boot file
140 WARN( not want_boot && mi_boot iface, ppr imp_mod_name )
142 -- Issue a user warning for a redundant {- SOURCE -} import
143 -- NB that we arrange to read all the ordinary imports before
144 -- any of the {- SOURCE -} imports
145 warnIf (want_boot && not (mi_boot iface))
146 (warnRedundantSourceImport imp_mod_name) `thenM_`
149 imp_mod = mi_module iface
150 deprecs = mi_deprecs iface
151 is_orph = mi_orphan iface
154 filtered_exports = filter not_this_mod (mi_exports iface)
155 not_this_mod (mod,_) = mod /= this_mod_name
156 -- If the module exports anything defined in this module, just ignore it.
157 -- Reason: otherwise it looks as if there are two local definition sites
158 -- for the thing, and an error gets reported. Easiest thing is just to
159 -- filter them out up front. This situation only arises if a module
160 -- imports itself, or another module that imported it. (Necessarily,
161 -- this invoves a loop.)
163 -- Tiresome consequence: if you say
168 -- module B( AType ) where
169 -- import {-# SOURCE #-} A( AType )
171 -- then you'll get a 'B does not export AType' message. Oh well.
173 exportsToAvails filtered_exports `thenM` \ avails ->
175 -- Filter the imports according to the import list
176 filterImports imp_mod want_boot imp_details avails `thenM` \ (filtered_avails, explicits) ->
179 -- Compute new transitive dependencies
180 orphans | is_orph = insert imp_mod_name (dep_orphs deps)
181 | otherwise = dep_orphs deps
183 (dependent_mods, dependent_pkgs)
184 | isHomeModule imp_mod
185 = -- Imported module is from the home package
186 -- Take its dependent modules and
187 -- (a) remove this_mod (might be there as a hi-boot)
188 -- (b) add imp_mod itself
189 -- Take its dependent packages unchanged
190 ((imp_mod_name, want_boot) : filter not_self (dep_mods deps), dep_pkgs deps)
193 = -- Imported module is from another package
194 -- Dump the dependent modules
195 -- Add the package imp_mod comes from to the dependent packages
197 ([], insert (mi_package iface) (dep_pkgs deps))
199 not_self (m, _) = m /= this_mod_name
201 import_all = case imp_details of
202 Just (is_hiding, ls) -- Imports are spec'd explicitly
203 | not is_hiding -> Just (not (null ls))
204 _ -> Nothing -- Everything is imported,
205 -- (or almost everything [hiding])
207 qual_mod_name = case as_mod of
208 Nothing -> imp_mod_name
209 Just another_name -> another_name
211 -- unqual_avails is the Avails that are visible in *unqualified* form
212 -- We need to know this so we know what to export when we see
213 -- module M ( module P ) where ...
214 -- Then we must export whatever came from P unqualified.
215 imp_spec = ImportSpec { is_mod = imp_mod_name, is_qual = qual_only,
216 is_loc = iloc , is_as = qual_mod_name }
217 mk_deprec = mi_dep_fn iface
218 gres = [ GRE { gre_name = name,
219 gre_prov = Imported [imp_spec] (name `elemNameSet` explicits),
220 gre_deprec = mk_deprec name }
221 | avail <- filtered_avails, name <- availNames avail ]
222 gbl_env = mkGlobalRdrEnv gres
224 avail_env = mkAvailEnv filtered_avails
225 imports = ImportAvails {
226 imp_qual = unitModuleEnvByName qual_mod_name avail_env,
228 imp_mods = unitModuleEnv imp_mod (imp_mod, import_all),
230 imp_dep_mods = mkModDeps dependent_mods,
231 imp_dep_pkgs = dependent_pkgs }
234 -- Complain if we import a deprecated module
235 ifOptM Opt_WarnDeprecations (
237 DeprecAll txt -> addWarn (moduleDeprec imp_mod_name txt)
241 returnM (gbl_env, imports)
243 exportsToAvails :: [IfaceExport] -> TcRnIf gbl lcl Avails
244 exportsToAvails exports
245 = do { avails_by_module <- mappM do_one exports
246 ; return (concat avails_by_module) }
248 do_one (mod_name, exports) = mapM (do_avail mod_name) exports
249 do_avail mod_nm (Avail n) = do { n' <- lookupOrig mod_nm n;
250 ; return (Avail n') }
251 do_avail mod_nm (AvailTC n ns) = do { n' <- lookupOrig mod_nm n
252 ; ns' <- mappM (lookup_sub n') ns
253 ; return (AvailTC n' ns') }
255 mod = mkPackageModule mod_nm -- Not necessarily right yet
256 lookup_sub parent occ = newGlobalBinder mod occ (Just parent) noSrcLoc
257 -- Hack alert! Notice the newGlobalBinder. It ensures that the subordinate
258 -- names record their parent; and that in turn ensures that the GlobalRdrEnv
259 -- has the correct parent for all the names in its range.
260 -- For imported things, we only suck in the binding site later, if ever.
261 -- Reason for all this:
262 -- Suppose module M exports type A.T, and constructor A.MkT
263 -- Then, we know that A.MkT is a subordinate name of A.T,
264 -- even though we aren't at the binding site of A.T
265 -- And it's important, because we may simply re-export A.T
266 -- without ever sucking in the declaration itself.
268 warnRedundantSourceImport mod_name
269 = ptext SLIT("Unnecessary {- SOURCE -} in the import of module")
270 <+> quotes (ppr mod_name)
274 %************************************************************************
276 importsFromLocalDecls
278 %************************************************************************
280 From the top-level declarations of this module produce
281 * the lexical environment
283 created by its bindings.
285 Complain about duplicate bindings
288 importsFromLocalDecls :: HsGroup RdrName
289 -> RnM (GlobalRdrEnv, ImportAvails)
290 importsFromLocalDecls group
291 = getModule `thenM` \ this_mod ->
292 getLocalDeclBinders this_mod group `thenM` \ avails ->
293 -- The avails that are returned don't include the "system" names
295 all_names :: [Name] -- All the defns; no dups eliminated
296 all_names = [name | avail <- avails, name <- availNames avail]
299 (_, dups) = removeDups compare all_names
301 -- Check for duplicate definitions
302 -- The complaint will come out as "Multiple declarations of Foo.f" because
303 -- since 'f' is in the env twice, the unQualInScope used by the error-msg
304 -- printer returns False. It seems awkward to fix, unfortunately.
305 mappM_ (addErr . dupDeclErr) dups `thenM_`
307 doptM Opt_NoImplicitPrelude `thenM` \ implicit_prelude ->
309 mod_name = moduleName this_mod
310 prov = LocalDef mod_name
311 gbl_env = mkGlobalRdrEnv gres
312 gres = [ GRE { gre_name = name, gre_prov = prov, gre_deprec = Nothing}
314 -- gre_deprecs = Nothing: don't deprecate locally defined names
315 -- For a start, we may be exporting a deprecated thing
316 -- Also we may use a deprecated thing in the defn of another
317 -- deprecated things. We may even use a deprecated thing in
318 -- the defn of a non-deprecated thing, when changing a module's
322 -- Optimisation: filter out names for built-in syntax
323 -- They just clutter up the environment (esp tuples), and the parser
324 -- will generate Exact RdrNames for them, so the cluttered
325 -- envt is no use. To avoid doing this filter all the time,
326 -- we use -fno-implicit-prelude as a clue that the filter is
327 -- worth while. Really, it's only useful for GHC.Base and GHC.Tuple.
329 -- It's worth doing because it makes the environment smaller for
330 -- every module that imports the Prelude
332 -- Note: don't filter the gbl_env (hence avails, not avails' in
333 -- defn of gbl_env above). Stupid reason: when parsing
334 -- data type decls, the constructors start as Exact tycon-names,
335 -- and then get turned into data con names by zapping the name space;
336 -- but that stops them being Exact, so they get looked up.
337 -- Ditto in fixity decls; e.g. infix 5 :
338 -- Sigh. It doesn't matter because it only affects the Data.Tuple really.
339 -- The important thing is to trim down the exports.
341 avails' | implicit_prelude = filter not_built_in_syntax avails
343 not_built_in_syntax a = not (all isBuiltInSyntaxName (availNames a))
344 -- Only filter it if all the names of the avail are built-in
345 -- In particular, lists have (:) which is not built in syntax
346 -- so we don't filter it out. [Sept 03: wrong: see isBuiltInSyntaxName]
348 avail_env = mkAvailEnv avails'
349 imports = emptyImportAvails {
350 imp_qual = unitModuleEnv this_mod avail_env,
354 returnM (gbl_env, imports)
358 %*********************************************************
360 \subsection{Getting binders out of a declaration}
362 %*********************************************************
364 @getLocalDeclBinders@ returns the names for a @RdrNameHsDecl@. It's
365 used for both source code (from @importsFromLocalDecls@) and interface
366 files (@loadDecl@ calls @getTyClDeclBinders@).
368 *** See "THE NAMING STORY" in HsDecls ****
371 getLocalDeclBinders :: Module -> HsGroup RdrName -> RnM [AvailInfo]
372 getLocalDeclBinders mod (HsGroup {hs_valds = val_decls,
373 hs_tyclds = tycl_decls,
374 hs_fords = foreign_decls })
375 = -- For type and class decls, we generate Global names, with
376 -- no export indicator. They need to be global because they get
377 -- permanently bound into the TyCons and Classes. They don't need
378 -- an export indicator because they are all implicitly exported.
380 mappM new_tc tycl_decls `thenM` \ tc_avails ->
381 mappM new_simple (for_hs_bndrs ++ val_hs_bndrs) `thenM` \ simple_avails ->
382 returnM (tc_avails ++ simple_avails)
384 new_simple rdr_name = newTopSrcBinder mod Nothing rdr_name `thenM` \ name ->
387 val_hs_bndrs = collectLocatedHsBinders val_decls
388 for_hs_bndrs = [(nm,loc) | ForeignImport nm _ _ _ loc <- foreign_decls]
391 = newTopSrcBinder mod Nothing main_rdr `thenM` \ main_name ->
392 mappM (newTopSrcBinder mod (Just main_name)) sub_rdrs `thenM` \ sub_names ->
393 returnM (AvailTC main_name (main_name : sub_names))
395 (main_rdr : sub_rdrs) = tyClDeclNames tc_decl
399 %************************************************************************
401 \subsection{Filtering imports}
403 %************************************************************************
405 @filterImports@ takes the @ExportEnv@ telling what the imported module makes
406 available, and filters it through the import spec (if any).
409 filterImports :: Module -- The module being imported
410 -> IsBootInterface -- Tells whether it's a {-# SOURCE #-} import
411 -> Maybe (Bool, [RdrNameIE]) -- Import spec; True => hiding
412 -> [AvailInfo] -- What's available
413 -> RnM ([AvailInfo], -- What's imported
414 NameSet) -- What was imported explicitly
416 -- Complains if import spec mentions things that the module doesn't export
417 -- Warns/informs if import spec contains duplicates.
418 filterImports mod from Nothing imports
419 = returnM (imports, emptyNameSet)
421 filterImports mod from (Just (want_hiding, import_items)) total_avails
422 = mappM get_item import_items `thenM` \ avails_w_explicits_s ->
424 (item_avails, explicits_s) = unzip (concat avails_w_explicits_s)
425 explicits = foldl addListToNameSet emptyNameSet explicits_s
428 let -- All imported; item_avails to be hidden
429 hidden = availsToNameSet item_avails
430 keep n = not (n `elemNameSet` hidden)
432 returnM (pruneAvails keep total_avails, emptyNameSet)
434 -- Just item_avails imported; nothing to be hidden
435 returnM (item_avails, explicits)
437 import_fm :: FiniteMap OccName AvailInfo
438 import_fm = listToFM [ (nameOccName name, avail)
439 | avail <- total_avails,
440 name <- availNames avail]
441 -- Even though availNames returns data constructors too,
442 -- they won't make any difference because naked entities like T
443 -- in an import list map to TcOccs, not VarOccs.
445 bale_out item = addErr (badImportItemErr mod from item) `thenM_`
448 get_item :: RdrNameIE -> RnM [(AvailInfo, [Name])]
449 -- Empty list for a bad item.
450 -- Singleton is typical case.
451 -- Can have two when we are hiding, and mention C which might be
452 -- both a class and a data constructor.
453 -- The [Name] is the list of explicitly-mentioned names
454 get_item item@(IEModuleContents _) = bale_out item
456 get_item item@(IEThingAll _)
457 = case check_item item of
458 Nothing -> bale_out item
459 Just avail@(AvailTC _ [n]) -> -- This occurs when you import T(..), but
460 -- only export T abstractly. The single [n]
461 -- in the AvailTC is the type or class itself
462 ifOptM Opt_WarnMisc (addWarn (dodgyImportWarn mod item)) `thenM_`
463 returnM [(avail, [availName avail])]
464 Just avail -> returnM [(avail, [availName avail])]
466 get_item item@(IEThingAbs n)
467 | want_hiding -- hiding( C )
468 -- Here the 'C' can be a data constructor *or* a type/class
469 = case catMaybes [check_item item, check_item (IEVar data_n)] of
471 avails -> returnM [(a, []) | a <- avails]
472 -- The 'explicits' list is irrelevant when hiding
474 data_n = setRdrNameSpace n srcDataName
477 = case check_item item of
478 Nothing -> bale_out item
479 Just avail -> returnM [(avail, availNames avail)]
482 | isNothing maybe_in_import_avails ||
483 isNothing maybe_filtered_avail
487 = Just filtered_avail
490 wanted_occ = rdrNameOcc (ieName item)
491 maybe_in_import_avails = lookupFM import_fm wanted_occ
493 Just avail = maybe_in_import_avails
494 maybe_filtered_avail = filterAvail item avail
495 Just filtered_avail = maybe_filtered_avail
499 filterAvail :: RdrNameIE -- Wanted
500 -> AvailInfo -- Available
501 -> Maybe AvailInfo -- Resulting available;
502 -- Nothing if (any of the) wanted stuff isn't there
504 filterAvail ie@(IEThingWith want wants) avail@(AvailTC n ns)
505 | sub_names_ok = Just (AvailTC n (filter is_wanted ns))
506 | otherwise = Nothing
508 is_wanted name = nameOccName name `elem` wanted_occs
509 sub_names_ok = all (`elem` avail_occs) wanted_occs
510 avail_occs = map nameOccName ns
511 wanted_occs = map rdrNameOcc (want:wants)
513 filterAvail (IEThingAbs _) (AvailTC n ns) = ASSERT( n `elem` ns )
516 filterAvail (IEThingAbs _) avail@(Avail n) = Just avail -- Type synonyms
518 filterAvail (IEVar _) avail@(Avail n) = Just avail
519 filterAvail (IEVar v) avail@(AvailTC n ns) = Just (AvailTC n (filter wanted ns))
521 wanted n = nameOccName n == occ
523 -- The second equation happens if we import a class op, thus
525 -- where op is a class operation
527 filterAvail (IEThingAll _) avail@(AvailTC _ _) = Just avail
528 -- We don't complain even if the IE says T(..), but
529 -- no constrs/class ops of T are available
530 -- Instead that's caught with a warning by the caller
532 filterAvail ie avail = Nothing
536 %************************************************************************
538 \subsection{Export list processing}
540 %************************************************************************
542 Processing the export list.
544 You might think that we should record things that appear in the export
545 list as ``occurrences'' (using @addOccurrenceName@), but you'd be
546 wrong. We do check (here) that they are in scope, but there is no
547 need to slurp in their actual declaration (which is what
548 @addOccurrenceName@ forces).
550 Indeed, doing so would big trouble when compiling @PrelBase@, because
551 it re-exports @GHC@, which includes @takeMVar#@, whose type includes
552 @ConcBase.StateAndSynchVar#@, and so on...
555 type ExportAccum -- The type of the accumulating parameter of
556 -- the main worker function in exportsFromAvail
557 = ([ModuleName], -- 'module M's seen so far
558 ExportOccMap, -- Tracks exported occurrence names
559 AvailEnv) -- The accumulated exported stuff, kept in an env
560 -- so we can common-up related AvailInfos
561 emptyExportAccum = ([], emptyFM, emptyAvailEnv)
563 type ExportOccMap = FiniteMap OccName (Name, RdrNameIE)
564 -- Tracks what a particular exported OccName
565 -- in an export list refers to, and which item
566 -- it came from. It's illegal to export two distinct things
567 -- that have the same occurrence name
570 exportsFromAvail :: Maybe Module -- Nothing => no 'module M(..) where' header at all
571 -> Maybe [RdrNameIE] -- Nothing => no explicit export list
573 -- Complains if two distinct exports have same OccName
574 -- Warns about identical exports.
575 -- Complains about exports items not in scope
577 exportsFromAvail maybe_mod exports
578 = do { TcGblEnv { tcg_rdr_env = rdr_env,
579 tcg_imports = imports } <- getGblEnv ;
581 -- If the module header is omitted altogether, then behave
582 -- as if the user had written "module Main(main) where..."
583 -- EXCEPT in interactive mode, when we behave as if he had
584 -- written "module Main where ..."
585 -- Reason: don't want to complain about 'main' not in scope
586 -- in interactive mode
587 ghci_mode <- getGhciMode ;
591 Nothing | ghci_mode == Interactive -> Nothing
592 | otherwise -> Just [IEVar main_RDR_Unqual] } ;
594 exports_from_avail real_exports rdr_env imports }
596 exports_from_avail Nothing rdr_env
597 imports@(ImportAvails { imp_env = entity_avail_env })
598 = -- Export all locally-defined things
599 -- We do this by filtering the global RdrEnv,
600 -- keeping only things that are (a) qualified,
601 -- (b) locally defined, (c) a 'main' name
602 -- Then we look up in the entity-avail-env
603 return [ lookupAvailEnv entity_avail_env name
604 | gre <- globalRdrEnvElts rdr_env,
606 let name = gre_name gre,
607 isNothing (nameParent_maybe name) -- Main things only
610 exports_from_avail (Just export_items) rdr_env
611 (ImportAvails { imp_qual = mod_avail_env,
612 imp_env = entity_avail_env })
613 = foldlM exports_from_item emptyExportAccum
614 export_items `thenM` \ (_, _, export_avail_map) ->
615 returnM (nameEnvElts export_avail_map)
618 exports_from_item :: ExportAccum -> RdrNameIE -> RnM ExportAccum
620 exports_from_item acc@(mods, occs, avails) ie@(IEModuleContents mod)
621 | mod `elem` mods -- Duplicate export of M
622 = do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
623 warnIf warn_dup_exports (dupModuleExport mod) ;
627 = case lookupModuleEnvByName mod_avail_env mod of
628 Nothing -> addErr (modExportErr mod) `thenM_`
633 mod_avails = [ filtered_avail
634 | avail <- availEnvElts avail_env,
635 let mb_avail = filter_unqual rdr_env avail,
637 let Just filtered_avail = mb_avail]
639 avails' = foldl addAvail avails mod_avails
641 -- This check_occs not only finds conflicts between this item
642 -- and others, but also internally within this item. That is,
643 -- if 'M.x' is in scope in several ways, we'll have several
644 -- members of mod_avails with the same OccName.
646 foldlM (check_occs ie) occs mod_avails `thenM` \ occs' ->
647 returnM (mod:mods, occs', avails')
649 exports_from_item acc@(mods, occs, avails) ie
650 = lookupGlobalOccRn (ieName ie) `thenM` \ name ->
651 if isUnboundName name then
652 returnM acc -- Avoid error cascade
654 -- Get the AvailInfo for the parent of the specified name
656 parent = nameParent name
657 avail = lookupAvailEnv entity_avail_env parent
659 -- Filter out the bits we want
660 case filterAvail ie avail of {
661 Nothing -> -- Not enough availability
662 addErr (exportItemErr ie) `thenM_`
667 -- Phew! It's OK! Now to check the occurrence stuff!
668 warnIf (not (ok_item ie avail)) (dodgyExportWarn ie) `thenM_`
669 check_occs ie occs export_avail `thenM` \ occs' ->
670 returnM (mods, occs', addAvail avails export_avail)
674 -------------------------------
675 filter_unqual :: GlobalRdrEnv -> AvailInfo -> Maybe AvailInfo
676 -- Filter the Avail by what's in scope unqualified
677 filter_unqual env (Avail n)
678 | in_scope env n = Just (Avail n)
679 | otherwise = Nothing
680 filter_unqual env (AvailTC n ns)
681 | not (null ns') = Just (AvailTC n ns')
682 | otherwise = Nothing
684 ns' = filter (in_scope env) ns
686 in_scope :: GlobalRdrEnv -> Name -> Bool
687 -- Checks whether the Name is in scope unqualified,
688 -- regardless of whether it's ambiguous or not
689 in_scope env n = any unQualOK (lookupGRE_Name env n)
692 -------------------------------
693 ok_item (IEThingAll _) (AvailTC _ [n]) = False
694 -- This occurs when you import T(..), but
695 -- only export T abstractly. The single [n]
696 -- in the AvailTC is the type or class itself
699 -------------------------------
700 check_occs :: RdrNameIE -> ExportOccMap -> AvailInfo -> RnM ExportOccMap
701 check_occs ie occs avail
702 = foldlM check occs (availNames avail)
705 = case lookupFM occs name_occ of
706 Nothing -> returnM (addToFM occs name_occ (name, ie))
709 | name == name' -- Duplicate export
710 -> do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
711 warnIf warn_dup_exports (dupExportWarn name_occ ie ie') ;
714 | otherwise -- Same occ name but different names: an error
715 -> do { global_env <- getGlobalRdrEnv ;
716 addErr (exportClashErr global_env name name' ie ie') ;
719 name_occ = nameOccName name
722 %*********************************************************
724 \subsection{Unused names}
726 %*********************************************************
729 reportUnusedNames :: TcGblEnv -> RnM ()
730 reportUnusedNames gbl_env
731 = warnUnusedModules unused_imp_mods `thenM_`
732 warnUnusedTopBinds bad_locals `thenM_`
733 warnUnusedImports bad_imports `thenM_`
734 printMinimalImports minimal_imports
736 used_names, all_used_names :: NameSet
737 used_names = findUses (tcg_dus gbl_env) emptyNameSet
738 all_used_names = used_names `unionNameSets`
739 mkNameSet (mapCatMaybes nameParent_maybe (nameSetToList used_names))
740 -- A use of C implies a use of T,
741 -- if C was brought into scope by T(..) or T(C)
743 -- Collect the defined names from the in-scope environment
744 defined_names :: [GlobalRdrElt]
745 defined_names = globalRdrEnvElts (tcg_rdr_env gbl_env)
747 defined_and_used, defined_but_not_used :: [GlobalRdrElt]
748 (defined_and_used, defined_but_not_used) = partition is_used defined_names
750 is_used gre = gre_name gre `elemNameSet` all_used_names
752 -- Filter out the ones that are
753 -- (a) defined in this module, and
754 -- (b) not defined by a 'deriving' clause
755 -- The latter have an Internal Name, so we can filter them out easily
756 bad_locals :: [GlobalRdrElt]
757 bad_locals = filter is_bad defined_but_not_used
758 is_bad :: GlobalRdrElt -> Bool
759 is_bad gre = isLocalGRE gre && isExternalName (gre_name gre)
761 bad_imports :: [GlobalRdrElt]
762 bad_imports = filter bad_imp defined_but_not_used
763 bad_imp (GRE {gre_prov = Imported imp_specs True})
764 = not (all (module_unused . is_mod) imp_specs)
765 -- Don't complain about unused imports if we've already said the
766 -- entire import is unused
767 bad_imp other = False
769 -- To figure out the minimal set of imports, start with the things
770 -- that are in scope (i.e. in gbl_env). Then just combine them
771 -- into a bunch of avails, so they are properly grouped
772 minimal_imports :: FiniteMap ModuleName AvailEnv
773 minimal_imports0 = emptyFM
774 minimal_imports1 = foldr add_name minimal_imports0 defined_and_used
775 minimal_imports = foldr add_inst_mod minimal_imports1 direct_import_mods
776 -- The last line makes sure that we retain all direct imports
777 -- even if we import nothing explicitly.
778 -- It's not necessarily redundant to import such modules. Consider
782 -- The import M() is not *necessarily* redundant, even if
783 -- we suck in no instance decls from M (e.g. it contains
784 -- no instance decls, or This contains no code). It may be
785 -- that we import M solely to ensure that M's orphan instance
786 -- decls (or those in its imports) are visible to people who
787 -- import This. Sigh.
788 -- There's really no good way to detect this, so the error message
789 -- in RnEnv.warnUnusedModules is weakened instead
792 -- We've carefully preserved the provenance so that we can
793 -- construct minimal imports that import the name by (one of)
794 -- the same route(s) as the programmer originally did.
795 add_name (GRE {gre_name = n,
796 gre_prov = Imported imp_specs _}) acc
797 = addToFM_C plusAvailEnv acc (is_mod (head imp_specs))
798 (unitAvailEnv (mk_avail n (nameParent_maybe n)))
802 -- n is the name of the thing, p is the name of its parent
803 mk_avail n (Just p) = AvailTC p [p,n]
804 mk_avail n Nothing | isTcOcc (nameOccName n) = AvailTC n [n]
805 | otherwise = Avail n
808 | m `elemFM` acc = acc -- We import something already
809 | otherwise = addToFM acc m emptyAvailEnv
810 -- Add an empty collection of imports for a module
811 -- from which we have sucked only instance decls
813 imports = tcg_imports gbl_env
815 direct_import_mods :: [ModuleName]
816 direct_import_mods = map (moduleName . fst)
817 (moduleEnvElts (imp_mods imports))
819 hasEmptyImpList :: ModuleName -> Bool
821 case lookupModuleEnvByName (imp_mods imports) m of
822 Just (_,Just x) -> not x
825 -- unused_imp_mods are the directly-imported modules
826 -- that are not mentioned in minimal_imports1
827 -- [Note: not 'minimal_imports', because that includes direcly-imported
828 -- modules even if we use nothing from them; see notes above]
829 unused_imp_mods = [m | m <- direct_import_mods,
830 isNothing (lookupFM minimal_imports1 m),
832 not (hasEmptyImpList m)]
833 -- hasEmptyImpList arranges not to complain about
834 -- import M (), which is an idiom for importing
835 -- instance declarations
837 module_unused :: ModuleName -> Bool
838 module_unused mod = mod `elem` unused_imp_mods
841 -- ToDo: deal with original imports with 'qualified' and 'as M' clauses
842 printMinimalImports :: FiniteMap ModuleName AvailEnv -- Minimal imports
844 printMinimalImports imps
845 = ifOptM Opt_D_dump_minimal_imports $ do {
847 mod_ies <- mappM to_ies (fmToList imps) ;
848 this_mod <- getModule ;
849 rdr_env <- getGlobalRdrEnv ;
850 ioToTcRn (do { h <- openFile (mkFilename this_mod) WriteMode ;
851 printForUser h (unQualInScope rdr_env)
852 (vcat (map ppr_mod_ie mod_ies)) })
855 mkFilename this_mod = moduleNameUserString (moduleName this_mod) ++ ".imports"
856 ppr_mod_ie (mod_name, ies)
857 | mod_name == pRELUDE_Name
859 | null ies -- Nothing except instances comes from here
860 = ptext SLIT("import") <+> ppr mod_name <> ptext SLIT("() -- Instances only")
862 = ptext SLIT("import") <+> ppr mod_name <>
863 parens (fsep (punctuate comma (map ppr ies)))
865 to_ies (mod, avail_env) = mappM to_ie (availEnvElts avail_env) `thenM` \ ies ->
868 to_ie :: AvailInfo -> RnM (IE Name)
869 -- The main trick here is that if we're importing all the constructors
870 -- we want to say "T(..)", but if we're importing only a subset we want
871 -- to say "T(A,B,C)". So we have to find out what the module exports.
872 to_ie (Avail n) = returnM (IEVar n)
873 to_ie (AvailTC n [m]) = ASSERT( n==m )
874 returnM (IEThingAbs n)
876 = loadSrcInterface doc n_mod False `thenM` \ iface ->
877 case [xs | (m,as) <- mi_exports iface,
880 x == nameOccName n] of
881 [xs] | all_used xs -> returnM (IEThingAll n)
882 | otherwise -> returnM (IEThingWith n (filter (/= n) ns))
883 other -> pprTrace "to_ie" (ppr n <+> ppr n_mod <+> ppr other) $
886 all_used avail_occs = all (`elem` map nameOccName ns) avail_occs
887 doc = text "Compute minimal imports from" <+> ppr n
888 n_mod = nameModuleName n
892 %************************************************************************
896 %************************************************************************
899 badImportItemErr mod from ie
900 = sep [ptext SLIT("Module"), quotes (ppr mod), source_import,
901 ptext SLIT("does not export"), quotes (ppr ie)]
903 source_import = case from of
904 True -> ptext SLIT("(hi-boot interface)")
907 dodgyImportWarn mod item = dodgyMsg (ptext SLIT("import")) item
908 dodgyExportWarn item = dodgyMsg (ptext SLIT("export")) item
910 dodgyMsg kind item@(IEThingAll tc)
911 = sep [ ptext SLIT("The") <+> kind <+> ptext SLIT("item") <+> quotes (ppr item),
912 ptext SLIT("suggests that") <+> quotes (ppr tc) <+> ptext SLIT("has constructor or class methods"),
913 ptext SLIT("but it has none; it is a type synonym or abstract type or class") ]
916 = hsep [ ptext SLIT("Unknown module in export list: module"), quotes (ppr mod)]
918 exportItemErr export_item
919 = sep [ ptext SLIT("The export item") <+> quotes (ppr export_item),
920 ptext SLIT("attempts to export constructors or class methods that are not visible here") ]
922 exportClashErr global_env name1 name2 ie1 ie2
923 = vcat [ ptext SLIT("Conflicting exports for") <+> quotes (ppr occ) <> colon
924 , ppr_export ie1 name1
925 , ppr_export ie2 name2 ]
927 occ = nameOccName name1
928 ppr_export ie name = nest 2 (quotes (ppr ie) <+> ptext SLIT("exports") <+>
929 quotes (ppr name) <+> pprNameProvenance (get_gre name))
931 -- get_gre finds a GRE for the Name, so that we can show its provenance
933 = case lookupGRE_Name global_env name of
935 [] -> pprPanic "exportClashErr" (ppr name)
938 = vcat [ptext SLIT("Multiple declarations of") <+> quotes (ppr n),
939 nest 4 (vcat (map ppr sorted_locs))]
941 sorted_locs = sortLt occ'ed_before (map nameSrcLoc (n:ns))
942 occ'ed_before a b = LT == compare a b
944 dupExportWarn occ_name ie1 ie2
945 = hsep [quotes (ppr occ_name),
946 ptext SLIT("is exported by"), quotes (ppr ie1),
947 ptext SLIT("and"), quotes (ppr ie2)]
950 = hsep [ptext SLIT("Duplicate"),
951 quotes (ptext SLIT("Module") <+> ppr mod),
952 ptext SLIT("in export list")]
955 = sep [ ptext SLIT("Module") <+> quotes (ppr mod) <+> ptext SLIT("is deprecated:"),