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,
38 IsBootInterface, WhetherHasOrphans,
39 availName, availNames, availsToNameSet,
40 Deprecations(..), ModIface(..),
41 GlobalRdrElt(..), unQualInScope, isLocalGRE
43 import RdrName ( RdrName, rdrNameOcc, setRdrNameSpace,
44 emptyRdrEnv, foldRdrEnv, isQual )
46 import Maybes ( maybeToBool, 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
145 avails = [ avail | (mod_name, avails) <- avails_by_module,
146 mod_name /= this_mod_name,
148 this_mod_name = moduleName this_mod
149 -- If the module exports anything defined in this module, just ignore it.
150 -- Reason: otherwise it looks as if there are two local definition sites
151 -- for the thing, and an error gets reported. Easiest thing is just to
152 -- filter them out up front. This situation only arises if a module
153 -- imports itself, or another module that imported it. (Necessarily,
154 -- this invoves a loop.)
156 -- Tiresome consequence: if you say
161 -- module B( AType ) where
162 -- import {-# SOURCE #-} A( AType )
164 -- then you'll get a 'B does not export AType' message. Oh well.
167 -- Filter the imports according to the import list
168 filterImports imp_mod is_boot imp_spec avails `thenM` \ (filtered_avails, explicits) ->
171 (sub_dep_mods, sub_dep_pkgs) = mi_deps iface
173 -- Compute new transitive dependencies: take the ones in
174 -- the interface and add
175 (dependent_mods, dependent_pkgs)
176 | isHomeModule imp_mod
177 = -- Imported module is from the home package
178 -- Take its dependent modules and
179 -- (a) remove this_mod (might be there as a hi-boot)
180 -- (b) add imp_mod itself
181 -- Take its dependent packages unchanged
182 ((imp_mod_name, is_orph, is_boot) : filter not_self sub_dep_mods,
185 = -- Imported module is from another package
186 -- Take only the orphan modules from its dependent modules
187 -- (sigh! it would be better to dump them entirely)
188 -- Add the package imp_mod comes from to the dependent packages
190 (filter sub_is_orph sub_dep_mods,
191 insert (mi_package iface) sub_dep_pkgs)
193 not_self (m, _, _) = m /= this_mod_name
194 sub_is_orph (_, orph, _) = orph
196 import_all = case imp_spec of
197 (Just (False, _)) -> False -- Imports are spec'd explicitly
198 other -> True -- Everything is imported,
199 -- (or almost everything [hiding])
201 qual_mod_name = case as_mod of
202 Nothing -> imp_mod_name
203 Just another_name -> another_name
205 -- unqual_avails is the Avails that are visible in *unqualified* form
206 -- We need to know this so we know what to export when we see
207 -- module M ( module P ) where ...
208 -- Then we must export whatever came from P unqualified.
209 avail_env = mkAvailEnv filtered_avails
210 unqual_avails | qual_only = emptyAvailEnv -- Qualified import
211 | otherwise = avail_env -- Unqualified import
213 mk_prov name = NonLocalDef (UserImport imp_mod iloc (name `elemNameSet` explicits))
214 gbl_env = mkGlobalRdrEnv qual_mod_name (not qual_only)
215 mk_prov filtered_avails deprecs
216 imports = ImportAvails {
217 imp_unqual = unitModuleEnvByName qual_mod_name unqual_avails,
219 imp_mods = unitModuleEnv imp_mod (imp_mod, import_all),
220 dep_mods = mkModDeps dependent_mods,
221 dep_pkgs = dependent_pkgs }
224 -- Complain if we import a deprecated module
225 ifOptM Opt_WarnDeprecations (
227 DeprecAll txt -> addWarn (moduleDeprec imp_mod_name txt)
231 returnM (gbl_env, imports)
234 mkModDeps :: [(ModuleName, WhetherHasOrphans, IsBootInterface)]
235 -> ModuleEnv (ModuleName, WhetherHasOrphans, IsBootInterface)
236 mkModDeps deps = foldl add emptyModuleEnv deps
238 add env elt@(m,_,_) = extendModuleEnvByName env m elt
242 %************************************************************************
244 importsFromLocalDecls
246 %************************************************************************
248 From the top-level declarations of this module produce
249 * the lexical environment
251 created by its bindings.
253 Complain about duplicate bindings
256 importsFromLocalDecls :: HsGroup RdrName
257 -> TcRn m (GlobalRdrEnv, ImportAvails)
258 importsFromLocalDecls group
259 = getModule `thenM` \ this_mod ->
260 getLocalDeclBinders this_mod group `thenM` \ avails ->
261 -- The avails that are returned don't include the "system" names
263 all_names :: [Name] -- All the defns; no dups eliminated
264 all_names = [name | avail <- avails, name <- availNames avail]
267 (_, dups) = removeDups compare all_names
269 -- Check for duplicate definitions
270 -- The complaint will come out as "Multiple declarations of Foo.f" because
271 -- since 'f' is in the env twice, the unQualInScope used by the error-msg
272 -- printer returns False. It seems awkward to fix, unfortunately.
273 mappM_ (addErr . dupDeclErr) dups `thenM_`
275 doptM Opt_NoImplicitPrelude `thenM` \ implicit_prelude ->
277 mod_name = moduleName this_mod
278 mk_prov n = LocalDef -- Provenance is local
280 unqual_imp = True -- Want unqualified names in scope
281 gbl_env = mkGlobalRdrEnv mod_name unqual_imp mk_prov avails NoDeprecs
282 -- NoDeprecs: don't complain about locally defined names
283 -- For a start, we may be exporting a deprecated thing
284 -- Also we may use a deprecated thing in the defn of another
285 -- deprecated things. We may even use a deprecated thing in
286 -- the defn of a non-deprecated thing, when changing a module's
290 -- Optimisation: filter out names for built-in syntax
291 -- They just clutter up the environment (esp tuples), and the parser
292 -- will generate Exact RdrNames for them, so the cluttered
293 -- envt is no use. To avoid doing this filter all the time,
294 -- we use -fno-implicit-prelude as a clue that the filter is
295 -- worth while. Really, it's only useful for GHC.Base and GHC.Tuple.
297 -- It's worth doing because it makes the environment smaller for
298 -- every module that imports the Prelude
300 -- Note: don't filter the gbl_env (hence avails, not avails' in
301 -- defn of gbl_env above). Stupid reason: when parsing
302 -- data type decls, the constructors start as Exact tycon-names,
303 -- and then get turned into data con names by zapping the name space;
304 -- but that stops them being Exact, so they get looked up. Sigh.
305 -- It doesn't matter because it only affects the Data.Tuple really.
306 -- The important thing is to trim down the exports.
308 avails' | implicit_prelude = filter not_built_in_syntax avails
310 not_built_in_syntax a = not (all isBuiltInSyntaxName (availNames a))
311 -- Only filter it if all the names of the avail are built-in
312 -- In particular, lists have (:) which is not built in syntax
313 -- so we don't filter it out.
315 avail_env = mkAvailEnv avails'
316 imports = emptyImportAvails {
317 imp_unqual = unitModuleEnv this_mod avail_env,
321 returnM (gbl_env, imports)
325 %*********************************************************
327 \subsection{Getting binders out of a declaration}
329 %*********************************************************
331 @getLocalDeclBinders@ returns the names for a @RdrNameHsDecl@. It's
332 used for both source code (from @importsFromLocalDecls@) and interface
333 files (@loadDecl@ calls @getTyClDeclBinders@).
335 *** See "THE NAMING STORY" in HsDecls ****
338 getLocalDeclBinders :: Module -> HsGroup RdrName -> TcRn m [AvailInfo]
339 getLocalDeclBinders mod (HsGroup {hs_valds = val_decls,
340 hs_tyclds = tycl_decls,
341 hs_fords = foreign_decls })
342 = -- For type and class decls, we generate Global names, with
343 -- no export indicator. They need to be global because they get
344 -- permanently bound into the TyCons and Classes. They don't need
345 -- an export indicator because they are all implicitly exported.
347 mappM new_tc tycl_decls `thenM` \ tc_avails ->
348 mappM new_bndr (for_hs_bndrs ++ val_hs_bndrs) `thenM` \ simple_bndrs ->
350 returnM (tc_avails ++ map Avail simple_bndrs)
352 new_bndr (rdr_name,loc) = newTopBinder mod rdr_name loc
354 val_hs_bndrs = collectLocatedHsBinders val_decls
355 for_hs_bndrs = [(nm,loc) | ForeignImport nm _ _ _ loc <- foreign_decls]
357 new_tc tc_decl = mappM new_bndr (tyClDeclNames tc_decl) `thenM` \ names@(main_name:_) ->
358 returnM (AvailTC main_name names)
362 %************************************************************************
364 \subsection{Filtering imports}
366 %************************************************************************
368 @filterImports@ takes the @ExportEnv@ telling what the imported module makes
369 available, and filters it through the import spec (if any).
372 filterImports :: Module -- The module being imported
373 -> IsBootInterface -- Tells whether it's a {-# SOURCE #-} import
374 -> Maybe (Bool, [RdrNameIE]) -- Import spec; True => hiding
375 -> [AvailInfo] -- What's available
376 -> TcRn m ([AvailInfo], -- What's imported
377 NameSet) -- What was imported explicitly
379 -- Complains if import spec mentions things that the module doesn't export
380 -- Warns/informs if import spec contains duplicates.
381 filterImports mod from Nothing imports
382 = returnM (imports, emptyNameSet)
384 filterImports mod from (Just (want_hiding, import_items)) total_avails
385 = mappM get_item import_items `thenM` \ avails_w_explicits_s ->
387 (item_avails, explicits_s) = unzip (concat avails_w_explicits_s)
388 explicits = foldl addListToNameSet emptyNameSet explicits_s
391 let -- All imported; item_avails to be hidden
392 hidden = availsToNameSet item_avails
393 keep n = not (n `elemNameSet` hidden)
395 returnM (pruneAvails keep total_avails, emptyNameSet)
397 -- Just item_avails imported; nothing to be hidden
398 returnM (item_avails, explicits)
400 import_fm :: FiniteMap OccName AvailInfo
401 import_fm = listToFM [ (nameOccName name, avail)
402 | avail <- total_avails,
403 name <- availNames avail]
404 -- Even though availNames returns data constructors too,
405 -- they won't make any difference because naked entities like T
406 -- in an import list map to TcOccs, not VarOccs.
408 bale_out item = addErr (badImportItemErr mod from item) `thenM_`
411 get_item :: RdrNameIE -> TcRn m [(AvailInfo, [Name])]
412 -- Empty list for a bad item.
413 -- Singleton is typical case.
414 -- Can have two when we are hiding, and mention C which might be
415 -- both a class and a data constructor.
416 -- The [Name] is the list of explicitly-mentioned names
417 get_item item@(IEModuleContents _) = bale_out item
419 get_item item@(IEThingAll _)
420 = case check_item item of
421 Nothing -> bale_out item
422 Just avail@(AvailTC _ [n]) -> -- This occurs when you import T(..), but
423 -- only export T abstractly. The single [n]
424 -- in the AvailTC is the type or class itself
425 ifOptM Opt_WarnMisc (addWarn (dodgyImportWarn mod item)) `thenM_`
426 returnM [(avail, [availName avail])]
427 Just avail -> returnM [(avail, [availName avail])]
429 get_item item@(IEThingAbs n)
430 | want_hiding -- hiding( C )
431 -- Here the 'C' can be a data constructor *or* a type/class
432 = case catMaybes [check_item item, check_item (IEVar data_n)] of
434 avails -> returnM [(a, []) | a <- avails]
435 -- The 'explicits' list is irrelevant when hiding
437 data_n = setRdrNameSpace n dataName
440 = case check_item item of
441 Nothing -> bale_out item
442 Just avail -> returnM [(avail, availNames avail)]
445 | not (maybeToBool maybe_in_import_avails) ||
446 not (maybeToBool maybe_filtered_avail)
450 = Just filtered_avail
453 wanted_occ = rdrNameOcc (ieName item)
454 maybe_in_import_avails = lookupFM import_fm wanted_occ
456 Just avail = maybe_in_import_avails
457 maybe_filtered_avail = filterAvail item avail
458 Just filtered_avail = maybe_filtered_avail
462 filterAvail :: RdrNameIE -- Wanted
463 -> AvailInfo -- Available
464 -> Maybe AvailInfo -- Resulting available;
465 -- Nothing if (any of the) wanted stuff isn't there
467 filterAvail ie@(IEThingWith want wants) avail@(AvailTC n ns)
468 | sub_names_ok = Just (AvailTC n (filter is_wanted ns))
469 | otherwise = Nothing
471 is_wanted name = nameOccName name `elem` wanted_occs
472 sub_names_ok = all (`elem` avail_occs) wanted_occs
473 avail_occs = map nameOccName ns
474 wanted_occs = map rdrNameOcc (want:wants)
476 filterAvail (IEThingAbs _) (AvailTC n ns) = ASSERT( n `elem` ns )
479 filterAvail (IEThingAbs _) avail@(Avail n) = Just avail -- Type synonyms
481 filterAvail (IEVar _) avail@(Avail n) = Just avail
482 filterAvail (IEVar v) avail@(AvailTC n ns) = Just (AvailTC n (filter wanted ns))
484 wanted n = nameOccName n == occ
486 -- The second equation happens if we import a class op, thus
488 -- where op is a class operation
490 filterAvail (IEThingAll _) avail@(AvailTC _ _) = Just avail
491 -- We don't complain even if the IE says T(..), but
492 -- no constrs/class ops of T are available
493 -- Instead that's caught with a warning by the caller
495 filterAvail ie avail = Nothing
499 %************************************************************************
501 \subsection{Export list processing}
503 %************************************************************************
505 Processing the export list.
507 You might think that we should record things that appear in the export
508 list as ``occurrences'' (using @addOccurrenceName@), but you'd be
509 wrong. We do check (here) that they are in scope, but there is no
510 need to slurp in their actual declaration (which is what
511 @addOccurrenceName@ forces).
513 Indeed, doing so would big trouble when compiling @PrelBase@, because
514 it re-exports @GHC@, which includes @takeMVar#@, whose type includes
515 @ConcBase.StateAndSynchVar#@, and so on...
518 type ExportAccum -- The type of the accumulating parameter of
519 -- the main worker function in exportsFromAvail
520 = ([ModuleName], -- 'module M's seen so far
521 ExportOccMap, -- Tracks exported occurrence names
522 AvailEnv) -- The accumulated exported stuff, kept in an env
523 -- so we can common-up related AvailInfos
524 emptyExportAccum = ([], emptyFM, emptyAvailEnv)
526 type ExportOccMap = FiniteMap OccName (Name, RdrNameIE)
527 -- Tracks what a particular exported OccName
528 -- in an export list refers to, and which item
529 -- it came from. It's illegal to export two distinct things
530 -- that have the same occurrence name
533 exportsFromAvail :: Maybe [RdrNameIE] -> TcRn m Avails
534 -- Complains if two distinct exports have same OccName
535 -- Warns about identical exports.
536 -- Complains about exports items not in scope
537 exportsFromAvail Nothing
538 = do { this_mod <- getModule ;
539 if moduleName this_mod == mAIN_Name then
541 -- Export nothing; Main.$main is automatically exported
543 exportsFromAvail (Just [IEModuleContents (moduleName this_mod)])
544 -- but for all other modules export everything.
547 exportsFromAvail (Just exports)
548 = do { TcGblEnv { tcg_imports = imports } <- getGblEnv ;
549 warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
550 exports_from_avail exports warn_dup_exports imports }
552 exports_from_avail export_items warn_dup_exports
553 (ImportAvails { imp_unqual = mod_avail_env,
554 imp_env = entity_avail_env })
555 = foldlM exports_from_item emptyExportAccum
556 export_items `thenM` \ (_, _, export_avail_map) ->
557 returnM (nameEnvElts export_avail_map)
560 exports_from_item :: ExportAccum -> RdrNameIE -> TcRn m ExportAccum
562 exports_from_item acc@(mods, occs, avails) ie@(IEModuleContents mod)
563 | mod `elem` mods -- Duplicate export of M
564 = warnIf warn_dup_exports (dupModuleExport mod) `thenM_`
568 = case lookupModuleEnvByName mod_avail_env mod of
569 Nothing -> addErr (modExportErr mod) `thenM_`
573 mod_avails = availEnvElts avail_env
574 avails' = foldl addAvail avails mod_avails
576 foldlM (check_occs warn_dup_exports ie)
577 occs mod_avails `thenM` \ occs' ->
579 returnM (mod:mods, occs', avails')
581 exports_from_item acc@(mods, occs, avails) ie
582 = lookupGRE (ieName ie) `thenM` \ mb_gre ->
584 Nothing -> addErr (unknownNameErr (ieName ie)) `thenM_`
588 -- Get the AvailInfo for the parent of the specified name
589 case lookupAvailEnv entity_avail_env (gre_parent gre) of {
590 Nothing -> pprPanic "exportsFromAvail"
591 ((ppr (ieName ie)) <+> ppr gre) ;
594 -- Filter out the bits we want
595 case filterAvail ie avail of {
596 Nothing -> -- Not enough availability
597 addErr (exportItemErr ie) `thenM_`
602 -- Phew! It's OK! Now to check the occurrence stuff!
603 warnIf (not (ok_item ie avail)) (dodgyExportWarn ie) `thenM_`
604 check_occs warn_dup_exports ie occs export_avail `thenM` \ occs' ->
605 returnM (mods, occs', addAvail avails export_avail)
610 ok_item (IEThingAll _) (AvailTC _ [n]) = False
611 -- This occurs when you import T(..), but
612 -- only export T abstractly. The single [n]
613 -- in the AvailTC is the type or class itself
616 check_occs :: Bool -> RdrNameIE -> ExportOccMap -> AvailInfo -> TcRn m ExportOccMap
617 check_occs warn_dup_exports ie occs avail
618 = foldlM check occs (availNames avail)
621 = case lookupFM occs name_occ of
622 Nothing -> returnM (addToFM occs name_occ (name, ie))
624 | name == name' -> -- Duplicate export
625 warnIf warn_dup_exports
626 (dupExportWarn name_occ ie ie')
627 `thenM_` returnM occs
629 | otherwise -> -- Same occ name but different names: an error
630 addErr (exportClashErr name_occ ie ie') `thenM_`
633 name_occ = nameOccName name
636 %*********************************************************
638 \subsection{Unused names}
640 %*********************************************************
643 reportUnusedNames :: TcGblEnv
644 -> NameSet -- Used in this module
646 reportUnusedNames gbl_env used_names
647 = warnUnusedModules unused_imp_mods `thenM_`
648 warnUnusedTopBinds bad_locals `thenM_`
649 warnUnusedImports bad_imports `thenM_`
650 printMinimalImports minimal_imports
652 direct_import_mods :: [ModuleName]
653 direct_import_mods = map (moduleName . fst)
654 (moduleEnvElts (imp_mods (tcg_imports gbl_env)))
656 -- Now, a use of C implies a use of T,
657 -- if C was brought into scope by T(..) or T(C)
658 really_used_names :: NameSet
659 really_used_names = used_names `unionNameSets`
660 mkNameSet [ gre_parent gre
661 | gre <- defined_names,
662 gre_name gre `elemNameSet` used_names]
664 -- Collect the defined names from the in-scope environment
665 -- Look for the qualified ones only, else get duplicates
666 defined_names :: [GlobalRdrElt]
667 defined_names = foldRdrEnv add [] (tcg_rdr_env gbl_env)
668 add rdr_name ns acc | isQual rdr_name = ns ++ acc
671 defined_and_used, defined_but_not_used :: [GlobalRdrElt]
672 (defined_and_used, defined_but_not_used) = partition used defined_names
673 used gre = gre_name gre `elemNameSet` really_used_names
675 -- Filter out the ones that are
676 -- (a) defined in this module, and
677 -- (b) not defined by a 'deriving' clause
678 -- The latter have an Internal Name, so we can filter them out easily
679 bad_locals :: [GlobalRdrElt]
680 bad_locals = filter is_bad defined_but_not_used
682 is_bad :: GlobalRdrElt -> Bool
683 is_bad gre = isLocalGRE gre && isExternalName (gre_name gre)
685 bad_imports :: [GlobalRdrElt]
686 bad_imports = filter bad_imp defined_but_not_used
687 bad_imp (GRE {gre_prov = NonLocalDef (UserImport mod _ True)}) = not (module_unused mod)
688 bad_imp other = False
690 -- To figure out the minimal set of imports, start with the things
691 -- that are in scope (i.e. in gbl_env). Then just combine them
692 -- into a bunch of avails, so they are properly grouped
693 minimal_imports :: FiniteMap ModuleName AvailEnv
694 minimal_imports0 = emptyFM
695 minimal_imports1 = foldr add_name minimal_imports0 defined_and_used
696 minimal_imports = foldr add_inst_mod minimal_imports1 direct_import_mods
697 -- The last line makes sure that we retain all direct imports
698 -- even if we import nothing explicitly.
699 -- It's not necessarily redundant to import such modules. Consider
703 -- The import M() is not *necessarily* redundant, even if
704 -- we suck in no instance decls from M (e.g. it contains
705 -- no instance decls, or This contains no code). It may be
706 -- that we import M solely to ensure that M's orphan instance
707 -- decls (or those in its imports) are visible to people who
708 -- import This. Sigh.
709 -- There's really no good way to detect this, so the error message
710 -- in RnEnv.warnUnusedModules is weakened instead
713 -- We've carefully preserved the provenance so that we can
714 -- construct minimal imports that import the name by (one of)
715 -- the same route(s) as the programmer originally did.
716 add_name (GRE {gre_name = n, gre_parent = p,
717 gre_prov = NonLocalDef (UserImport m _ _)}) acc
718 = addToFM_C plusAvailEnv acc (moduleName m)
719 (unitAvailEnv (mk_avail n p))
723 -- n is the name of the thing, p is the name of its parent
724 mk_avail n p | n/=p = AvailTC p [p,n]
725 | isTcOcc (nameOccName p) = AvailTC n [n]
726 | otherwise = Avail n
729 | m `elemFM` acc = acc -- We import something already
730 | otherwise = addToFM acc m emptyAvailEnv
731 -- Add an empty collection of imports for a module
732 -- from which we have sucked only instance decls
734 -- unused_imp_mods are the directly-imported modules
735 -- that are not mentioned in minimal_imports1
736 -- [Note: not 'minimal_imports', because that includes direcly-imported
737 -- modules even if we use nothing from them; see notes above]
738 unused_imp_mods = [m | m <- direct_import_mods,
739 not (maybeToBool (lookupFM minimal_imports1 m)),
742 module_unused :: Module -> Bool
743 module_unused mod = moduleName mod `elem` unused_imp_mods
746 -- ToDo: deal with original imports with 'qualified' and 'as M' clauses
747 printMinimalImports :: FiniteMap ModuleName AvailEnv -- Minimal imports
749 printMinimalImports imps
750 = ifOptM Opt_D_dump_minimal_imports $ do {
752 mod_ies <- mappM to_ies (fmToList imps) ;
753 this_mod <- getModule ;
754 rdr_env <- getGlobalRdrEnv ;
755 ioToTcRn (do { h <- openFile (mkFilename this_mod) WriteMode ;
756 printForUser h (unQualInScope rdr_env)
757 (vcat (map ppr_mod_ie mod_ies)) })
760 mkFilename this_mod = moduleNameUserString (moduleName this_mod) ++ ".imports"
761 ppr_mod_ie (mod_name, ies)
762 | mod_name == pRELUDE_Name
764 | null ies -- Nothing except instances comes from here
765 = ptext SLIT("import") <+> ppr mod_name <> ptext SLIT("() -- Instances only")
767 = ptext SLIT("import") <+> ppr mod_name <>
768 parens (fsep (punctuate comma (map ppr ies)))
770 to_ies (mod, avail_env) = mappM to_ie (availEnvElts avail_env) `thenM` \ ies ->
773 to_ie :: AvailInfo -> TcRn m (IE Name)
774 -- The main trick here is that if we're importing all the constructors
775 -- we want to say "T(..)", but if we're importing only a subset we want
776 -- to say "T(A,B,C)". So we have to find out what the module exports.
777 to_ie (Avail n) = returnM (IEVar n)
778 to_ie (AvailTC n [m]) = ASSERT( n==m )
779 returnM (IEThingAbs n)
781 = loadInterface (text "Compute minimal imports from" <+> ppr n_mod)
782 n_mod ImportBySystem `thenM` \ iface ->
783 case [xs | (m,as) <- mi_exports iface,
787 [xs] | all (`elem` ns) xs -> returnM (IEThingAll n)
788 | otherwise -> returnM (IEThingWith n (filter (/= n) ns))
789 other -> pprTrace "to_ie" (ppr n <+> ppr (nameModule n) <+> ppr other) $
792 n_mod = moduleName (nameModule n)
796 %************************************************************************
800 %************************************************************************
803 badImportItemErr mod from ie
804 = sep [ptext SLIT("Module"), quotes (ppr mod), source_import,
805 ptext SLIT("does not export"), quotes (ppr ie)]
807 source_import = case from of
808 True -> ptext SLIT("(hi-boot interface)")
811 dodgyImportWarn mod item = dodgyMsg (ptext SLIT("import")) item
812 dodgyExportWarn item = dodgyMsg (ptext SLIT("export")) item
814 dodgyMsg kind item@(IEThingAll tc)
815 = sep [ ptext SLIT("The") <+> kind <+> ptext SLIT("item") <+> quotes (ppr item),
816 ptext SLIT("suggests that") <+> quotes (ppr tc) <+> ptext SLIT("has constructor or class methods"),
817 ptext SLIT("but it has none; it is a type synonym or abstract type or class") ]
820 = hsep [ ptext SLIT("Unknown module in export list: module"), quotes (ppr mod)]
822 exportItemErr export_item
823 = sep [ ptext SLIT("The export item") <+> quotes (ppr export_item),
824 ptext SLIT("attempts to export constructors or class methods that are not visible here") ]
826 exportClashErr occ_name ie1 ie2
827 = hsep [ptext SLIT("The export items"), quotes (ppr ie1)
828 ,ptext SLIT("and"), quotes (ppr ie2)
829 ,ptext SLIT("create conflicting exports for"), quotes (ppr occ_name)]
832 = vcat [ptext SLIT("Multiple declarations of") <+> quotes (ppr n),
833 nest 4 (vcat (map ppr sorted_locs))]
835 sorted_locs = sortLt occ'ed_before (map nameSrcLoc (n:ns))
836 occ'ed_before a b = LT == compare a b
838 dupExportWarn occ_name ie1 ie2
839 = hsep [quotes (ppr occ_name),
840 ptext SLIT("is exported by"), quotes (ppr ie1),
841 ptext SLIT("and"), quotes (ppr ie2)]
844 = hsep [ptext SLIT("Duplicate"),
845 quotes (ptext SLIT("Module") <+> ppr mod),
846 ptext SLIT("in export list")]
849 = sep [ ptext SLIT("Module") <+> quotes (ppr mod) <+> ptext SLIT("is deprecated:"),