2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[RnNames]{Extracting imported and top-level names in scope}
8 rnImports, importsFromLocalDecls, exportsFromAvail,
9 reportUnusedNames, mkModDeps
12 #include "HsVersions.h"
14 import {-# SOURCE #-} RnHiFiles ( loadInterface )
16 import CmdLineOpts ( DynFlag(..) )
18 import HsSyn ( IE(..), ieName, ImportDecl(..),
19 ForeignDecl(..), HsGroup(..),
20 collectLocatedHsBinders, tyClDeclNames
22 import RdrHsSyn ( RdrNameIE, RdrNameImportDecl )
27 import PrelNames ( pRELUDE_Name, mAIN_Name, isBuiltInSyntaxName )
28 import Module ( Module, ModuleName, ModuleEnv, moduleName,
29 moduleNameUserString, isHomeModule,
30 emptyModuleEnv, unitModuleEnvByName, unitModuleEnv,
31 lookupModuleEnvByName, extendModuleEnvByName, moduleEnvElts )
32 import Name ( Name, nameSrcLoc, nameOccName, nameModule, isExternalName )
35 import OccName ( OccName, dataName, isTcOcc )
36 import HscTypes ( Provenance(..), ImportReason(..), GlobalRdrEnv,
37 GenAvailInfo(..), AvailInfo, Avails,
39 availName, availNames, availsToNameSet,
40 Deprecations(..), ModIface(..), Dependencies(..),
41 GlobalRdrElt(..), unQualInScope, isLocalGRE
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
146 avails = [ avail | (mod_name, avails) <- avails_by_module,
147 mod_name /= this_mod_name,
149 this_mod_name = moduleName this_mod
150 -- If the module exports anything defined in this module, just ignore it.
151 -- Reason: otherwise it looks as if there are two local definition sites
152 -- for the thing, and an error gets reported. Easiest thing is just to
153 -- filter them out up front. This situation only arises if a module
154 -- imports itself, or another module that imported it. (Necessarily,
155 -- this invoves a loop.)
157 -- Tiresome consequence: if you say
162 -- module B( AType ) where
163 -- import {-# SOURCE #-} A( AType )
165 -- then you'll get a 'B does not export AType' message. Oh well.
168 -- Filter the imports according to the import list
169 filterImports imp_mod is_boot imp_spec avails `thenM` \ (filtered_avails, explicits) ->
172 -- Compute new transitive dependencies
173 orphans | is_orph = insert imp_mod_name (dep_orphs deps)
174 | otherwise = dep_orphs deps
176 (dependent_mods, dependent_pkgs)
177 | isHomeModule imp_mod
178 = -- Imported module is from the home package
179 -- Take its dependent modules and
180 -- (a) remove this_mod (might be there as a hi-boot)
181 -- (b) add imp_mod itself
182 -- Take its dependent packages unchanged
183 ((imp_mod_name, is_boot) : filter not_self (dep_mods deps), dep_pkgs deps)
186 = -- Imported module is from another package
187 -- Dump the dependent modules
188 -- Add the package imp_mod comes from to the dependent packages
190 ([], insert (mi_package iface) (dep_pkgs deps))
192 not_self (m, _) = m /= this_mod_name
194 import_all = case imp_spec of
195 (Just (False, _)) -> False -- Imports are spec'd explicitly
196 other -> True -- Everything is imported,
197 -- (or almost everything [hiding])
199 qual_mod_name = case as_mod of
200 Nothing -> imp_mod_name
201 Just another_name -> another_name
203 -- unqual_avails is the Avails that are visible in *unqualified* form
204 -- We need to know this so we know what to export when we see
205 -- module M ( module P ) where ...
206 -- Then we must export whatever came from P unqualified.
207 avail_env = mkAvailEnv filtered_avails
208 unqual_avails | qual_only = emptyAvailEnv -- Qualified import
209 | otherwise = avail_env -- Unqualified import
211 mk_prov name = NonLocalDef (UserImport imp_mod iloc (name `elemNameSet` explicits))
212 gbl_env = mkGlobalRdrEnv qual_mod_name (not qual_only)
213 mk_prov filtered_avails deprecs
214 imports = ImportAvails {
215 imp_unqual = unitModuleEnvByName qual_mod_name unqual_avails,
217 imp_mods = unitModuleEnv imp_mod (imp_mod, import_all),
219 imp_dep_mods = mkModDeps dependent_mods,
220 imp_dep_pkgs = dependent_pkgs }
223 -- Complain if we import a deprecated module
224 ifOptM Opt_WarnDeprecations (
226 DeprecAll txt -> addWarn (moduleDeprec imp_mod_name txt)
230 returnM (gbl_env, imports)
233 mkModDeps :: [(ModuleName, IsBootInterface)]
234 -> ModuleEnv (ModuleName, IsBootInterface)
235 mkModDeps deps = foldl add emptyModuleEnv deps
237 add env elt@(m,_) = extendModuleEnvByName env m elt
241 %************************************************************************
243 importsFromLocalDecls
245 %************************************************************************
247 From the top-level declarations of this module produce
248 * the lexical environment
250 created by its bindings.
252 Complain about duplicate bindings
255 importsFromLocalDecls :: HsGroup RdrName
256 -> TcRn m (GlobalRdrEnv, ImportAvails)
257 importsFromLocalDecls group
258 = getModule `thenM` \ this_mod ->
259 getLocalDeclBinders this_mod group `thenM` \ avails ->
260 -- The avails that are returned don't include the "system" names
262 all_names :: [Name] -- All the defns; no dups eliminated
263 all_names = [name | avail <- avails, name <- availNames avail]
266 (_, dups) = removeDups compare all_names
268 -- Check for duplicate definitions
269 -- The complaint will come out as "Multiple declarations of Foo.f" because
270 -- since 'f' is in the env twice, the unQualInScope used by the error-msg
271 -- printer returns False. It seems awkward to fix, unfortunately.
272 mappM_ (addErr . dupDeclErr) dups `thenM_`
274 doptM Opt_NoImplicitPrelude `thenM` \ implicit_prelude ->
276 mod_name = moduleName this_mod
277 mk_prov n = LocalDef -- Provenance is local
279 unqual_imp = True -- Want unqualified names in scope
280 gbl_env = mkGlobalRdrEnv mod_name unqual_imp mk_prov avails NoDeprecs
281 -- NoDeprecs: don't complain about locally defined names
282 -- For a start, we may be exporting a deprecated thing
283 -- Also we may use a deprecated thing in the defn of another
284 -- deprecated things. We may even use a deprecated thing in
285 -- the defn of a non-deprecated thing, when changing a module's
289 -- Optimisation: filter out names for built-in syntax
290 -- They just clutter up the environment (esp tuples), and the parser
291 -- will generate Exact RdrNames for them, so the cluttered
292 -- envt is no use. To avoid doing this filter all the time,
293 -- we use -fno-implicit-prelude as a clue that the filter is
294 -- worth while. Really, it's only useful for GHC.Base and GHC.Tuple.
296 -- It's worth doing because it makes the environment smaller for
297 -- every module that imports the Prelude
299 -- Note: don't filter the gbl_env (hence avails, not avails' in
300 -- defn of gbl_env above). Stupid reason: when parsing
301 -- data type decls, the constructors start as Exact tycon-names,
302 -- and then get turned into data con names by zapping the name space;
303 -- but that stops them being Exact, so they get looked up. Sigh.
304 -- It doesn't matter because it only affects the Data.Tuple really.
305 -- The important thing is to trim down the exports.
307 avails' | implicit_prelude = filter not_built_in_syntax avails
309 not_built_in_syntax a = not (all isBuiltInSyntaxName (availNames a))
310 -- Only filter it if all the names of the avail are built-in
311 -- In particular, lists have (:) which is not built in syntax
312 -- so we don't filter it out.
314 avail_env = mkAvailEnv avails'
315 imports = emptyImportAvails {
316 imp_unqual = unitModuleEnv this_mod avail_env,
320 returnM (gbl_env, imports)
324 %*********************************************************
326 \subsection{Getting binders out of a declaration}
328 %*********************************************************
330 @getLocalDeclBinders@ returns the names for a @RdrNameHsDecl@. It's
331 used for both source code (from @importsFromLocalDecls@) and interface
332 files (@loadDecl@ calls @getTyClDeclBinders@).
334 *** See "THE NAMING STORY" in HsDecls ****
337 getLocalDeclBinders :: Module -> HsGroup RdrName -> TcRn m [AvailInfo]
338 getLocalDeclBinders mod (HsGroup {hs_valds = val_decls,
339 hs_tyclds = tycl_decls,
340 hs_fords = foreign_decls })
341 = -- For type and class decls, we generate Global names, with
342 -- no export indicator. They need to be global because they get
343 -- permanently bound into the TyCons and Classes. They don't need
344 -- an export indicator because they are all implicitly exported.
346 mappM new_tc tycl_decls `thenM` \ tc_avails ->
347 mappM new_bndr (for_hs_bndrs ++ val_hs_bndrs) `thenM` \ simple_bndrs ->
349 returnM (tc_avails ++ map Avail simple_bndrs)
351 new_bndr (rdr_name,loc) = newTopBinder mod rdr_name loc
353 val_hs_bndrs = collectLocatedHsBinders val_decls
354 for_hs_bndrs = [(nm,loc) | ForeignImport nm _ _ _ loc <- foreign_decls]
356 new_tc tc_decl = mappM new_bndr (tyClDeclNames tc_decl) `thenM` \ names@(main_name:_) ->
357 returnM (AvailTC main_name names)
361 %************************************************************************
363 \subsection{Filtering imports}
365 %************************************************************************
367 @filterImports@ takes the @ExportEnv@ telling what the imported module makes
368 available, and filters it through the import spec (if any).
371 filterImports :: Module -- The module being imported
372 -> IsBootInterface -- Tells whether it's a {-# SOURCE #-} import
373 -> Maybe (Bool, [RdrNameIE]) -- Import spec; True => hiding
374 -> [AvailInfo] -- What's available
375 -> TcRn m ([AvailInfo], -- What's imported
376 NameSet) -- What was imported explicitly
378 -- Complains if import spec mentions things that the module doesn't export
379 -- Warns/informs if import spec contains duplicates.
380 filterImports mod from Nothing imports
381 = returnM (imports, emptyNameSet)
383 filterImports mod from (Just (want_hiding, import_items)) total_avails
384 = mappM get_item import_items `thenM` \ avails_w_explicits_s ->
386 (item_avails, explicits_s) = unzip (concat avails_w_explicits_s)
387 explicits = foldl addListToNameSet emptyNameSet explicits_s
390 let -- All imported; item_avails to be hidden
391 hidden = availsToNameSet item_avails
392 keep n = not (n `elemNameSet` hidden)
394 returnM (pruneAvails keep total_avails, emptyNameSet)
396 -- Just item_avails imported; nothing to be hidden
397 returnM (item_avails, explicits)
399 import_fm :: FiniteMap OccName AvailInfo
400 import_fm = listToFM [ (nameOccName name, avail)
401 | avail <- total_avails,
402 name <- availNames avail]
403 -- Even though availNames returns data constructors too,
404 -- they won't make any difference because naked entities like T
405 -- in an import list map to TcOccs, not VarOccs.
407 bale_out item = addErr (badImportItemErr mod from item) `thenM_`
410 get_item :: RdrNameIE -> TcRn m [(AvailInfo, [Name])]
411 -- Empty list for a bad item.
412 -- Singleton is typical case.
413 -- Can have two when we are hiding, and mention C which might be
414 -- both a class and a data constructor.
415 -- The [Name] is the list of explicitly-mentioned names
416 get_item item@(IEModuleContents _) = bale_out item
418 get_item item@(IEThingAll _)
419 = case check_item item of
420 Nothing -> bale_out item
421 Just avail@(AvailTC _ [n]) -> -- This occurs when you import T(..), but
422 -- only export T abstractly. The single [n]
423 -- in the AvailTC is the type or class itself
424 ifOptM Opt_WarnMisc (addWarn (dodgyImportWarn mod item)) `thenM_`
425 returnM [(avail, [availName avail])]
426 Just avail -> returnM [(avail, [availName avail])]
428 get_item item@(IEThingAbs n)
429 | want_hiding -- hiding( C )
430 -- Here the 'C' can be a data constructor *or* a type/class
431 = case catMaybes [check_item item, check_item (IEVar data_n)] of
433 avails -> returnM [(a, []) | a <- avails]
434 -- The 'explicits' list is irrelevant when hiding
436 data_n = setRdrNameSpace n dataName
439 = case check_item item of
440 Nothing -> bale_out item
441 Just avail -> returnM [(avail, availNames avail)]
444 | not (maybeToBool maybe_in_import_avails) ||
445 not (maybeToBool maybe_filtered_avail)
449 = Just filtered_avail
452 wanted_occ = rdrNameOcc (ieName item)
453 maybe_in_import_avails = lookupFM import_fm wanted_occ
455 Just avail = maybe_in_import_avails
456 maybe_filtered_avail = filterAvail item avail
457 Just filtered_avail = maybe_filtered_avail
461 filterAvail :: RdrNameIE -- Wanted
462 -> AvailInfo -- Available
463 -> Maybe AvailInfo -- Resulting available;
464 -- Nothing if (any of the) wanted stuff isn't there
466 filterAvail ie@(IEThingWith want wants) avail@(AvailTC n ns)
467 | sub_names_ok = Just (AvailTC n (filter is_wanted ns))
468 | otherwise = Nothing
470 is_wanted name = nameOccName name `elem` wanted_occs
471 sub_names_ok = all (`elem` avail_occs) wanted_occs
472 avail_occs = map nameOccName ns
473 wanted_occs = map rdrNameOcc (want:wants)
475 filterAvail (IEThingAbs _) (AvailTC n ns) = ASSERT( n `elem` ns )
478 filterAvail (IEThingAbs _) avail@(Avail n) = Just avail -- Type synonyms
480 filterAvail (IEVar _) avail@(Avail n) = Just avail
481 filterAvail (IEVar v) avail@(AvailTC n ns) = Just (AvailTC n (filter wanted ns))
483 wanted n = nameOccName n == occ
485 -- The second equation happens if we import a class op, thus
487 -- where op is a class operation
489 filterAvail (IEThingAll _) avail@(AvailTC _ _) = Just avail
490 -- We don't complain even if the IE says T(..), but
491 -- no constrs/class ops of T are available
492 -- Instead that's caught with a warning by the caller
494 filterAvail ie avail = Nothing
498 %************************************************************************
500 \subsection{Export list processing}
502 %************************************************************************
504 Processing the export list.
506 You might think that we should record things that appear in the export
507 list as ``occurrences'' (using @addOccurrenceName@), but you'd be
508 wrong. We do check (here) that they are in scope, but there is no
509 need to slurp in their actual declaration (which is what
510 @addOccurrenceName@ forces).
512 Indeed, doing so would big trouble when compiling @PrelBase@, because
513 it re-exports @GHC@, which includes @takeMVar#@, whose type includes
514 @ConcBase.StateAndSynchVar#@, and so on...
517 type ExportAccum -- The type of the accumulating parameter of
518 -- the main worker function in exportsFromAvail
519 = ([ModuleName], -- 'module M's seen so far
520 ExportOccMap, -- Tracks exported occurrence names
521 AvailEnv) -- The accumulated exported stuff, kept in an env
522 -- so we can common-up related AvailInfos
523 emptyExportAccum = ([], emptyFM, emptyAvailEnv)
525 type ExportOccMap = FiniteMap OccName (Name, RdrNameIE)
526 -- Tracks what a particular exported OccName
527 -- in an export list refers to, and which item
528 -- it came from. It's illegal to export two distinct things
529 -- that have the same occurrence name
532 exportsFromAvail :: Maybe [RdrNameIE] -> TcRn m Avails
533 -- Complains if two distinct exports have same OccName
534 -- Warns about identical exports.
535 -- Complains about exports items not in scope
536 exportsFromAvail Nothing
537 = do { this_mod <- getModule ;
538 if moduleName this_mod == mAIN_Name then
540 -- Export nothing; Main.$main is automatically exported
542 exportsFromAvail (Just [IEModuleContents (moduleName this_mod)])
543 -- but for all other modules export everything.
546 exportsFromAvail (Just exports)
547 = do { TcGblEnv { tcg_imports = imports } <- getGblEnv ;
548 warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
549 exports_from_avail exports warn_dup_exports imports }
551 exports_from_avail export_items warn_dup_exports
552 (ImportAvails { imp_unqual = mod_avail_env,
553 imp_env = entity_avail_env })
554 = foldlM exports_from_item emptyExportAccum
555 export_items `thenM` \ (_, _, export_avail_map) ->
556 returnM (nameEnvElts export_avail_map)
559 exports_from_item :: ExportAccum -> RdrNameIE -> TcRn m ExportAccum
561 exports_from_item acc@(mods, occs, avails) ie@(IEModuleContents mod)
562 | mod `elem` mods -- Duplicate export of M
563 = warnIf warn_dup_exports (dupModuleExport mod) `thenM_`
567 = case lookupModuleEnvByName mod_avail_env mod of
568 Nothing -> addErr (modExportErr mod) `thenM_`
572 mod_avails = availEnvElts avail_env
573 avails' = foldl addAvail avails mod_avails
575 foldlM (check_occs warn_dup_exports ie)
576 occs mod_avails `thenM` \ occs' ->
578 returnM (mod:mods, occs', avails')
580 exports_from_item acc@(mods, occs, avails) ie
581 = lookupGRE (ieName ie) `thenM` \ mb_gre ->
583 Nothing -> addErr (unknownNameErr (ieName ie)) `thenM_`
587 -- Get the AvailInfo for the parent of the specified name
588 case lookupAvailEnv entity_avail_env (gre_parent gre) of {
589 Nothing -> pprPanic "exportsFromAvail"
590 ((ppr (ieName ie)) <+> ppr gre) ;
593 -- Filter out the bits we want
594 case filterAvail ie avail of {
595 Nothing -> -- Not enough availability
596 addErr (exportItemErr ie) `thenM_`
601 -- Phew! It's OK! Now to check the occurrence stuff!
602 warnIf (not (ok_item ie avail)) (dodgyExportWarn ie) `thenM_`
603 check_occs warn_dup_exports ie occs export_avail `thenM` \ occs' ->
604 returnM (mods, occs', addAvail avails export_avail)
609 ok_item (IEThingAll _) (AvailTC _ [n]) = False
610 -- This occurs when you import T(..), but
611 -- only export T abstractly. The single [n]
612 -- in the AvailTC is the type or class itself
615 check_occs :: Bool -> RdrNameIE -> ExportOccMap -> AvailInfo -> TcRn m ExportOccMap
616 check_occs warn_dup_exports ie occs avail
617 = foldlM check occs (availNames avail)
620 = case lookupFM occs name_occ of
621 Nothing -> returnM (addToFM occs name_occ (name, ie))
623 | name == name' -> -- Duplicate export
624 warnIf warn_dup_exports
625 (dupExportWarn name_occ ie ie')
626 `thenM_` returnM occs
628 | otherwise -> -- Same occ name but different names: an error
629 addErr (exportClashErr name_occ ie ie') `thenM_`
632 name_occ = nameOccName name
635 %*********************************************************
637 \subsection{Unused names}
639 %*********************************************************
642 reportUnusedNames :: TcGblEnv
643 -> NameSet -- Used in this module
645 reportUnusedNames gbl_env used_names
646 = warnUnusedModules unused_imp_mods `thenM_`
647 warnUnusedTopBinds bad_locals `thenM_`
648 warnUnusedImports bad_imports `thenM_`
649 printMinimalImports minimal_imports
651 direct_import_mods :: [ModuleName]
652 direct_import_mods = map (moduleName . fst)
653 (moduleEnvElts (imp_mods (tcg_imports gbl_env)))
655 -- Now, a use of C implies a use of T,
656 -- if C was brought into scope by T(..) or T(C)
657 really_used_names :: NameSet
658 really_used_names = used_names `unionNameSets`
659 mkNameSet [ gre_parent gre
660 | gre <- defined_names,
661 gre_name gre `elemNameSet` used_names]
663 -- Collect the defined names from the in-scope environment
664 -- Look for the qualified ones only, else get duplicates
665 defined_names :: [GlobalRdrElt]
666 defined_names = foldRdrEnv add [] (tcg_rdr_env gbl_env)
667 add rdr_name ns acc | isQual rdr_name = ns ++ acc
670 defined_and_used, defined_but_not_used :: [GlobalRdrElt]
671 (defined_and_used, defined_but_not_used) = partition used defined_names
672 used gre = gre_name gre `elemNameSet` really_used_names
674 -- Filter out the ones that are
675 -- (a) defined in this module, and
676 -- (b) not defined by a 'deriving' clause
677 -- The latter have an Internal Name, so we can filter them out easily
678 bad_locals :: [GlobalRdrElt]
679 bad_locals = filter is_bad defined_but_not_used
681 is_bad :: GlobalRdrElt -> Bool
682 is_bad gre = isLocalGRE gre && isExternalName (gre_name gre)
684 bad_imports :: [GlobalRdrElt]
685 bad_imports = filter bad_imp defined_but_not_used
686 bad_imp (GRE {gre_prov = NonLocalDef (UserImport mod _ True)}) = not (module_unused mod)
687 bad_imp other = False
689 -- To figure out the minimal set of imports, start with the things
690 -- that are in scope (i.e. in gbl_env). Then just combine them
691 -- into a bunch of avails, so they are properly grouped
692 minimal_imports :: FiniteMap ModuleName AvailEnv
693 minimal_imports0 = emptyFM
694 minimal_imports1 = foldr add_name minimal_imports0 defined_and_used
695 minimal_imports = foldr add_inst_mod minimal_imports1 direct_import_mods
696 -- The last line makes sure that we retain all direct imports
697 -- even if we import nothing explicitly.
698 -- It's not necessarily redundant to import such modules. Consider
702 -- The import M() is not *necessarily* redundant, even if
703 -- we suck in no instance decls from M (e.g. it contains
704 -- no instance decls, or This contains no code). It may be
705 -- that we import M solely to ensure that M's orphan instance
706 -- decls (or those in its imports) are visible to people who
707 -- import This. Sigh.
708 -- There's really no good way to detect this, so the error message
709 -- in RnEnv.warnUnusedModules is weakened instead
712 -- We've carefully preserved the provenance so that we can
713 -- construct minimal imports that import the name by (one of)
714 -- the same route(s) as the programmer originally did.
715 add_name (GRE {gre_name = n, gre_parent = p,
716 gre_prov = NonLocalDef (UserImport m _ _)}) acc
717 = addToFM_C plusAvailEnv acc (moduleName m)
718 (unitAvailEnv (mk_avail n p))
722 -- n is the name of the thing, p is the name of its parent
723 mk_avail n p | n/=p = AvailTC p [p,n]
724 | isTcOcc (nameOccName p) = AvailTC n [n]
725 | otherwise = Avail n
728 | m `elemFM` acc = acc -- We import something already
729 | otherwise = addToFM acc m emptyAvailEnv
730 -- Add an empty collection of imports for a module
731 -- from which we have sucked only instance decls
733 -- unused_imp_mods are the directly-imported modules
734 -- that are not mentioned in minimal_imports1
735 -- [Note: not 'minimal_imports', because that includes direcly-imported
736 -- modules even if we use nothing from them; see notes above]
737 unused_imp_mods = [m | m <- direct_import_mods,
738 not (maybeToBool (lookupFM minimal_imports1 m)),
741 module_unused :: Module -> Bool
742 module_unused mod = moduleName mod `elem` unused_imp_mods
745 -- ToDo: deal with original imports with 'qualified' and 'as M' clauses
746 printMinimalImports :: FiniteMap ModuleName AvailEnv -- Minimal imports
748 printMinimalImports imps
749 = ifOptM Opt_D_dump_minimal_imports $ do {
751 mod_ies <- mappM to_ies (fmToList imps) ;
752 this_mod <- getModule ;
753 rdr_env <- getGlobalRdrEnv ;
754 ioToTcRn (do { h <- openFile (mkFilename this_mod) WriteMode ;
755 printForUser h (unQualInScope rdr_env)
756 (vcat (map ppr_mod_ie mod_ies)) })
759 mkFilename this_mod = moduleNameUserString (moduleName this_mod) ++ ".imports"
760 ppr_mod_ie (mod_name, ies)
761 | mod_name == pRELUDE_Name
763 | null ies -- Nothing except instances comes from here
764 = ptext SLIT("import") <+> ppr mod_name <> ptext SLIT("() -- Instances only")
766 = ptext SLIT("import") <+> ppr mod_name <>
767 parens (fsep (punctuate comma (map ppr ies)))
769 to_ies (mod, avail_env) = mappM to_ie (availEnvElts avail_env) `thenM` \ ies ->
772 to_ie :: AvailInfo -> TcRn m (IE Name)
773 -- The main trick here is that if we're importing all the constructors
774 -- we want to say "T(..)", but if we're importing only a subset we want
775 -- to say "T(A,B,C)". So we have to find out what the module exports.
776 to_ie (Avail n) = returnM (IEVar n)
777 to_ie (AvailTC n [m]) = ASSERT( n==m )
778 returnM (IEThingAbs n)
780 = loadInterface (text "Compute minimal imports from" <+> ppr n_mod)
781 n_mod ImportBySystem `thenM` \ iface ->
782 case [xs | (m,as) <- mi_exports iface,
786 [xs] | all (`elem` ns) xs -> returnM (IEThingAll n)
787 | otherwise -> returnM (IEThingWith n (filter (/= n) ns))
788 other -> pprTrace "to_ie" (ppr n <+> ppr (nameModule n) <+> ppr other) $
791 n_mod = moduleName (nameModule n)
795 %************************************************************************
799 %************************************************************************
802 badImportItemErr mod from ie
803 = sep [ptext SLIT("Module"), quotes (ppr mod), source_import,
804 ptext SLIT("does not export"), quotes (ppr ie)]
806 source_import = case from of
807 True -> ptext SLIT("(hi-boot interface)")
810 dodgyImportWarn mod item = dodgyMsg (ptext SLIT("import")) item
811 dodgyExportWarn item = dodgyMsg (ptext SLIT("export")) item
813 dodgyMsg kind item@(IEThingAll tc)
814 = sep [ ptext SLIT("The") <+> kind <+> ptext SLIT("item") <+> quotes (ppr item),
815 ptext SLIT("suggests that") <+> quotes (ppr tc) <+> ptext SLIT("has constructor or class methods"),
816 ptext SLIT("but it has none; it is a type synonym or abstract type or class") ]
819 = hsep [ ptext SLIT("Unknown module in export list: module"), quotes (ppr mod)]
821 exportItemErr export_item
822 = sep [ ptext SLIT("The export item") <+> quotes (ppr export_item),
823 ptext SLIT("attempts to export constructors or class methods that are not visible here") ]
825 exportClashErr occ_name ie1 ie2
826 = hsep [ptext SLIT("The export items"), quotes (ppr ie1)
827 ,ptext SLIT("and"), quotes (ppr ie2)
828 ,ptext SLIT("create conflicting exports for"), quotes (ppr occ_name)]
831 = vcat [ptext SLIT("Multiple declarations of") <+> quotes (ppr n),
832 nest 4 (vcat (map ppr sorted_locs))]
834 sorted_locs = sortLt occ'ed_before (map nameSrcLoc (n:ns))
835 occ'ed_before a b = LT == compare a b
837 dupExportWarn occ_name ie1 ie2
838 = hsep [quotes (ppr occ_name),
839 ptext SLIT("is exported by"), quotes (ppr ie1),
840 ptext SLIT("and"), quotes (ppr ie2)]
843 = hsep [ptext SLIT("Duplicate"),
844 quotes (ptext SLIT("Module") <+> ppr mod),
845 ptext SLIT("in export list")]
848 = sep [ ptext SLIT("Module") <+> quotes (ppr mod) <+> ptext SLIT("is deprecated:"),