2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[RnNames]{Extracting imported and top-level names in scope}
8 rnImports, getLocalNonValBinders,
9 rnExports, extendGlobalRdrEnvRn,
11 reportUnusedNames, finishWarnings,
14 #include "HsVersions.h"
18 import TcEnv ( isBrackStage )
20 import RnHsDoc ( rnHsDoc )
21 import IfaceEnv ( ifaceExportNames )
22 import LoadIface ( loadSrcInterface )
25 import HeaderInfo ( mkPrelImports )
40 import Data.List ( partition, (\\), delete )
41 import qualified Data.Set as Set
44 import Data.Map ( Map )
45 import qualified Data.Map as Map
50 %************************************************************************
52 \subsection{rnImports}
54 %************************************************************************
57 rnImports :: [LImportDecl RdrName]
58 -> RnM ([LImportDecl Name], GlobalRdrEnv, ImportAvails,AnyHpcUsage)
61 -- PROCESS IMPORT DECLS
62 -- Do the non {- SOURCE -} ones first, so that we get a helpful
63 -- warning for {- SOURCE -} ones that are unnecessary
64 = do this_mod <- getModule
65 implicit_prelude <- xoptM Opt_ImplicitPrelude
66 let prel_imports = mkPrelImports (moduleName this_mod) implicit_prelude imports
67 (source, ordinary) = partition is_source_import imports
68 is_source_import (L _ (ImportDecl _ _ is_boot _ _ _)) = is_boot
70 ifDOptM Opt_WarnImplicitPrelude (
71 when (notNull prel_imports) $ addWarn (implicitPreludeWarn)
74 stuff1 <- mapM (rnImportDecl this_mod True) prel_imports
75 stuff2 <- mapM (rnImportDecl this_mod False) ordinary
76 stuff3 <- mapM (rnImportDecl this_mod False) source
77 let (decls, rdr_env, imp_avails, hpc_usage) = combine (stuff1 ++ stuff2 ++ stuff3)
78 return (decls, rdr_env, imp_avails, hpc_usage)
81 combine :: [(LImportDecl Name, GlobalRdrEnv, ImportAvails,AnyHpcUsage)]
82 -> ([LImportDecl Name], GlobalRdrEnv, ImportAvails,AnyHpcUsage)
83 combine = foldr plus ([], emptyGlobalRdrEnv, emptyImportAvails,False)
84 where plus (decl, gbl_env1, imp_avails1,hpc_usage1)
85 (decls, gbl_env2, imp_avails2,hpc_usage2)
87 gbl_env1 `plusGlobalRdrEnv` gbl_env2,
88 imp_avails1 `plusImportAvails` imp_avails2,
89 hpc_usage1 || hpc_usage2)
91 rnImportDecl :: Module -> Bool
92 -> LImportDecl RdrName
93 -> RnM (LImportDecl Name, GlobalRdrEnv, ImportAvails,AnyHpcUsage)
95 rnImportDecl this_mod implicit_prelude
96 (L loc (ImportDecl { ideclName = loc_imp_mod_name, ideclPkgQual = mb_pkg
97 , ideclSource = want_boot, ideclQualified = qual_only
98 , ideclAs = as_mod, ideclHiding = imp_details }))
101 when (isJust mb_pkg) $ do
102 pkg_imports <- xoptM Opt_PackageImports
103 when (not pkg_imports) $ addErr packageImportErr
105 -- If there's an error in loadInterface, (e.g. interface
106 -- file not found) we get lots of spurious errors from 'filterImports'
108 imp_mod_name = unLoc loc_imp_mod_name
109 doc = ppr imp_mod_name <+> ptext (sLit "is directly imported")
111 -- Check for a missing import list
112 -- (Opt_WarnMissingImportList also checks for T(..) items
113 -- but that is done in checkDodgyImport below)
115 Just (False, _) -> return ()
116 _ | implicit_prelude -> return ()
117 | otherwise -> ifDOptM Opt_WarnMissingImportList $
118 addWarn (missingImportListWarn imp_mod_name)
120 iface <- loadSrcInterface doc imp_mod_name want_boot mb_pkg
122 -- Compiler sanity check: if the import didn't say
123 -- {-# SOURCE #-} we should not get a hi-boot file
124 WARN( not want_boot && mi_boot iface, ppr imp_mod_name ) (do
126 -- Issue a user warning for a redundant {- SOURCE -} import
127 -- NB that we arrange to read all the ordinary imports before
128 -- any of the {- SOURCE -} imports.
130 -- in --make and GHCi, the compilation manager checks for this,
131 -- and indeed we shouldn't do it here because the existence of
132 -- the non-boot module depends on the compilation order, which
133 -- is not deterministic. The hs-boot test can show this up.
135 warnIf (want_boot && not (mi_boot iface) && isOneShot (ghcMode dflags))
136 (warnRedundantSourceImport imp_mod_name)
139 imp_mod = mi_module iface
140 warns = mi_warns iface
141 orph_iface = mi_orphan iface
142 has_finsts = mi_finsts iface
145 filtered_exports = filter not_this_mod (mi_exports iface)
146 not_this_mod (mod,_) = mod /= this_mod
147 -- If the module exports anything defined in this module, just
148 -- ignore it. Reason: otherwise it looks as if there are two
149 -- local definition sites for the thing, and an error gets
150 -- reported. Easiest thing is just to filter them out up
151 -- front. This situation only arises if a module imports
152 -- itself, or another module that imported it. (Necessarily,
153 -- this invoves a loop.)
155 -- Tiresome consequence: if you say
160 -- module B( AType ) where
161 -- import {-# SOURCE #-} A( AType )
163 -- then you'll get a 'B does not export AType' message. Oh well.
165 qual_mod_name = case as_mod of
166 Nothing -> imp_mod_name
167 Just another_name -> another_name
168 imp_spec = ImpDeclSpec { is_mod = imp_mod_name, is_qual = qual_only,
169 is_dloc = loc, is_as = qual_mod_name }
171 -- Get the total exports from this module
172 total_avails <- ifaceExportNames filtered_exports
174 -- filter the imports according to the import declaration
175 (new_imp_details, gbl_env) <-
176 filterImports iface imp_spec imp_details total_avails
181 -- Compute new transitive dependencies
183 orphans | orph_iface = ASSERT( not (imp_mod `elem` dep_orphs deps) )
184 imp_mod : dep_orphs deps
185 | otherwise = dep_orphs deps
187 finsts | has_finsts = ASSERT( not (imp_mod `elem` dep_finsts deps) )
188 imp_mod : dep_finsts deps
189 | otherwise = dep_finsts deps
191 pkg = modulePackageId (mi_module iface)
193 (dependent_mods, dependent_pkgs)
194 | pkg == thisPackage dflags =
195 -- Imported module is from the home package
196 -- Take its dependent modules and add imp_mod itself
197 -- Take its dependent packages unchanged
199 -- NB: (dep_mods deps) might include a hi-boot file
200 -- for the module being compiled, CM. Do *not* filter
201 -- this out (as we used to), because when we've
202 -- finished dealing with the direct imports we want to
203 -- know if any of them depended on CM.hi-boot, in
204 -- which case we should do the hi-boot consistency
205 -- check. See LoadIface.loadHiBootInterface
206 ((imp_mod_name, want_boot) : dep_mods deps, dep_pkgs deps)
209 -- Imported module is from another package
210 -- Dump the dependent modules
211 -- Add the package imp_mod comes from to the dependent packages
212 ASSERT2( not (pkg `elem` dep_pkgs deps), ppr pkg <+> ppr (dep_pkgs deps) )
213 ([], pkg : dep_pkgs deps)
215 -- True <=> import M ()
216 import_all = case imp_details of
217 Just (is_hiding, ls) -> not is_hiding && null ls
220 imports = ImportAvails {
221 imp_mods = unitModuleEnv imp_mod [(qual_mod_name, import_all, loc)],
224 imp_dep_mods = mkModDeps dependent_mods,
225 imp_dep_pkgs = dependent_pkgs
228 -- Complain if we import a deprecated module
229 ifDOptM Opt_WarnWarningsDeprecations (
231 WarnAll txt -> addWarn (moduleWarn imp_mod_name txt)
235 let new_imp_decl = L loc (ImportDecl loc_imp_mod_name mb_pkg want_boot
236 qual_only as_mod new_imp_details)
238 return (new_imp_decl, gbl_env, imports, mi_hpc iface)
241 warnRedundantSourceImport :: ModuleName -> SDoc
242 warnRedundantSourceImport mod_name
243 = ptext (sLit "Unnecessary {-# SOURCE #-} in the import of module")
244 <+> quotes (ppr mod_name)
248 %************************************************************************
250 \subsection{importsFromLocalDecls}
252 %************************************************************************
254 From the top-level declarations of this module produce
255 * the lexical environment
257 created by its bindings.
259 Note [Top-level Names in Template Haskell decl quotes]
260 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
261 Consider a Template Haskell declaration quotation like this:
264 When renaming the declarations inside [d| ...|], we treat the
265 top level binders specially in two ways
267 1. We give them an Internal name, not (as usual) an External one.
268 Otherwise the NameCache gets confused by a second allocation of
269 M.f. (We used to invent a fake module ThFake to avoid this, but
270 that had other problems, notably in getting the correct answer for
271 nameIsLocalOrFrom in lookupFixity. So we now leave tcg_module
274 2. We make them *shadow* the outer bindings. If we don't do that,
275 we'll get a complaint when extending the GlobalRdrEnv, saying that
276 there are two bindings for 'f'. There are several tricky points:
278 * This shadowing applies even if the binding for 'f' is in a
279 where-clause, and hence is in the *local* RdrEnv not the *global*
282 * The *qualified* name M.f from the enclosing module must certainly
283 still be available. So we don't nuke it entirely; we just make
284 it seem like qualified import.
286 * We only shadow *External* names (which come from the main module)
287 Do not shadow *Inernal* names because in the bracket
288 [d| class C a where f :: a
290 rnSrcDecls will first call extendGlobalRdrEnvRn with C[f] from the
291 class decl, and *separately* extend the envt with the value binding.
293 3. We find out whether we are inside a [d| ... |] by testing the TH
294 stage. This is a slight hack, because the stage field was really
295 meant for the type checker, and here we are not interested in the
296 fields of Brack, hence the error thunks in thRnBrack.
299 extendGlobalRdrEnvRn :: [AvailInfo]
301 -> RnM (TcGblEnv, TcLclEnv)
302 -- Updates both the GlobalRdrEnv and the FixityEnv
303 -- We return a new TcLclEnv only because we might have to
304 -- delete some bindings from it;
305 -- see Note [Top-level Names in Template Haskell decl quotes]
307 extendGlobalRdrEnvRn avails new_fixities
308 = do { (gbl_env, lcl_env) <- getEnvs
310 ; let rdr_env = tcg_rdr_env gbl_env
311 fix_env = tcg_fix_env gbl_env
313 -- Delete new_occs from global and local envs
314 -- If we are in a TemplateHaskell decl bracket,
315 -- we are going to shadow them
316 -- See Note [Top-level Names in Template Haskell decl quotes]
317 shadowP = isBrackStage stage
318 new_occs = map (nameOccName . gre_name) gres
319 rdr_env1 = transformGREs qual_gre new_occs rdr_env
320 lcl_env1 = lcl_env { tcl_rdr = delListFromOccEnv (tcl_rdr lcl_env) new_occs }
321 (rdr_env2, lcl_env2) | shadowP = (rdr_env1, lcl_env1)
322 | otherwise = (rdr_env, lcl_env)
324 rdr_env3 = foldl extendGlobalRdrEnv rdr_env2 gres
325 fix_env' = foldl extend_fix_env fix_env gres
326 (rdr_env', dups) = findLocalDupsRdrEnv rdr_env3 new_occs
328 gbl_env' = gbl_env { tcg_rdr_env = rdr_env', tcg_fix_env = fix_env' }
330 ; mapM_ addDupDeclErr dups
332 ; traceRn (text "extendGlobalRdrEnvRn" <+> (ppr new_fixities $$ ppr fix_env $$ ppr fix_env'))
333 ; return (gbl_env', lcl_env2) }
335 gres = gresFromAvails LocalDef avails
337 -- If there is a fixity decl for the gre, add it to the fixity env
338 extend_fix_env fix_env gre
339 | Just (L _ fi) <- lookupFsEnv new_fixities (occNameFS occ)
340 = extendNameEnv fix_env name (FixItem occ fi)
345 occ = nameOccName name
347 qual_gre :: GlobalRdrElt -> GlobalRdrElt
348 -- Transform top-level GREs from the module being compiled
349 -- so that they are out of the way of new definitions in a Template
351 -- See Note [Top-level Names in Template Haskell decl quotes]
352 -- Seems like 5 times as much work as it deserves!
354 -- For a LocalDef we make a (fake) qualified imported GRE for a
355 -- local GRE so that the original *qualified* name is still in scope
356 -- but the *unqualified* one no longer is. What a hack!
358 qual_gre gre@(GRE { gre_prov = LocalDef, gre_name = name })
359 | isExternalName name = gre { gre_prov = Imported [imp_spec] }
361 -- Do not shadow Internal (ie Template Haskell) Names
362 -- See Note [Top-level Names in Template Haskell decl quotes]
364 mod = ASSERT2( isExternalName name, ppr name) moduleName (nameModule name)
365 imp_spec = ImpSpec { is_item = ImpAll, is_decl = decl_spec }
366 decl_spec = ImpDeclSpec { is_mod = mod, is_as = mod,
367 is_qual = True, -- Qualified only!
368 is_dloc = srcLocSpan (nameSrcLoc name) }
370 qual_gre gre@(GRE { gre_prov = Imported specs })
371 = gre { gre_prov = Imported (map qual_spec specs) }
373 qual_spec spec@(ImpSpec { is_decl = decl_spec })
374 = spec { is_decl = decl_spec { is_qual = True } }
377 @getLocalDeclBinders@ returns the names for an @HsDecl@. It's
378 used for source code.
380 *** See "THE NAMING STORY" in HsDecls ****
382 Instances of type families
383 ~~~~~~~~~~~~~~~~~~~~~~~~~~
384 Family instances contain data constructors that we need to collect and we also
385 need to descend into the type instances of associated families in class
386 instances. The type constructor of a family instance is a usage occurence.
387 Hence, we don't return it as a subname in 'AvailInfo'; otherwise, we would get
388 a duplicate declaration error.
390 Note [Looking up family names in family instances]
391 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
396 type instance M.T Int = Bool
398 We might think that we can simply use 'lookupOccRn' when processing the type
399 instance to look up 'M.T'. Alas, we can't! The type family declaration is in
400 the *same* HsGroup as the type instance declaration. Hence, as we are
401 currently collecting the binders declared in that HsGroup, these binders will
402 not have been added to the global environment yet.
404 In the case of type classes, this problem does not arise, as a class instance
405 does not define any binders of it's own. So, we simply don't attempt to look
406 up the class names of class instances in 'get_local_binders' below.
408 If we don't look up class instances, can't we get away without looking up type
409 instances, too? No, we can't. Data type instances define data constructors
412 (1) collect those in 'get_local_binders' and
413 (2) we need to get their parent name in 'get_local_binders', too, to
414 produce an appropriate 'AvailTC'.
416 This parent name is exactly the family name of the type instance that is so
417 difficult to look up.
419 We solve this problem as follows:
421 (a) We process all type declarations other than type instances first.
422 (b) Then, we compute a 'GlobalRdrEnv' from the result of the first step.
423 (c) Finally, we process all type instances (both those on the toplevel and
424 those nested in class instances) and check for the family names in the
425 'GlobalRdrEnv' produced in the previous step before using 'lookupOccRn'.
428 getLocalNonValBinders :: HsGroup RdrName -> RnM [AvailInfo]
429 -- Get all the top-level binders bound the group *except*
430 -- for value bindings, which are treated separately
431 -- Specificaly we return AvailInfo for
432 -- type decls (incl constructors and record selectors)
433 -- class decls (including class ops)
436 -- (in hs-boot files) value signatures
438 getLocalNonValBinders group
439 = do { gbl_env <- getGblEnv
440 ; get_local_binders gbl_env group }
442 get_local_binders :: TcGblEnv -> HsGroup RdrName -> RnM [GenAvailInfo Name]
443 get_local_binders gbl_env (HsGroup {hs_valds = ValBindsIn _ val_sigs,
444 hs_tyclds = tycl_decls,
445 hs_instds = inst_decls,
446 hs_fords = foreign_decls })
447 = do { -- separate out the family instance declarations
448 let (tyinst_decls1, tycl_decls_noinsts)
449 = partition (isFamInstDecl . unLoc) tycl_decls
450 tyinst_decls = tyinst_decls1 ++ instDeclATs inst_decls
452 -- process all type/class decls except family instances
453 ; tc_names <- mapM new_tc tycl_decls_noinsts
455 -- create a temporary rdr env of the type binders
456 ; let tc_gres = gresFromAvails LocalDef tc_names
457 tc_name_env = foldl extendGlobalRdrEnv emptyGlobalRdrEnv tc_gres
459 -- process all family instances
460 ; ti_names <- mapM (new_ti tc_name_env) tyinst_decls
462 -- finish off with value binder in case of a hs-boot file
463 ; val_names <- mapM new_simple val_bndrs
464 ; return (val_names ++ tc_names ++ ti_names) }
466 is_hs_boot = isHsBoot (tcg_src gbl_env) ;
468 for_hs_bndrs :: [Located RdrName]
469 for_hs_bndrs = [nm | L _ (ForeignImport nm _ _) <- foreign_decls]
471 -- In a hs-boot file, the value binders come from the
472 -- *signatures*, and there should be no foreign binders
473 val_bndrs :: [Located RdrName]
474 val_bndrs | is_hs_boot = [nm | L _ (TypeSig nm _) <- val_sigs]
475 | otherwise = for_hs_bndrs
477 new_simple :: Located RdrName -> RnM (GenAvailInfo Name)
478 new_simple rdr_name = do
479 nm <- newTopSrcBinder rdr_name
482 new_tc tc_decl -- NOT for type/data instances
483 = do { main_name <- newTopSrcBinder main_rdr
484 ; sub_names <- mapM newTopSrcBinder sub_rdrs
485 ; return (AvailTC main_name (main_name : sub_names)) }
487 (main_rdr : sub_rdrs) = hsTyClDeclBinders tc_decl
489 new_ti tc_name_env ti_decl -- ONLY for type/data instances
490 = do { main_name <- lookupFamInstDeclBndr tc_name_env main_rdr
491 ; sub_names <- mapM newTopSrcBinder sub_rdrs
492 ; return (AvailTC main_name sub_names) }
493 -- main_name is not bound here!
495 (main_rdr : sub_rdrs) = hsTyClDeclBinders ti_decl
497 get_local_binders _ g = pprPanic "get_local_binders" (ppr g)
501 %************************************************************************
503 \subsection{Filtering imports}
505 %************************************************************************
507 @filterImports@ takes the @ExportEnv@ telling what the imported module makes
508 available, and filters it through the import spec (if any).
511 filterImports :: ModIface
512 -> ImpDeclSpec -- The span for the entire import decl
513 -> Maybe (Bool, [LIE RdrName]) -- Import spec; True => hiding
514 -> [AvailInfo] -- What's available
515 -> RnM (Maybe (Bool, [LIE Name]), -- Import spec w/ Names
516 GlobalRdrEnv) -- Same again, but in GRE form
517 filterImports _ decl_spec Nothing all_avails
518 = return (Nothing, mkGlobalRdrEnv (gresFromAvails prov all_avails))
520 prov = Imported [ImpSpec { is_decl = decl_spec, is_item = ImpAll }]
523 filterImports iface decl_spec (Just (want_hiding, import_items)) all_avails
524 = do -- check for errors, convert RdrNames to Names
525 opt_typeFamilies <- xoptM Opt_TypeFamilies
526 items1 <- mapM (lookup_lie opt_typeFamilies) import_items
528 let items2 :: [(LIE Name, AvailInfo)]
529 items2 = concat items1
530 -- NB the AvailInfo may have duplicates, and several items
531 -- for the same parent; e.g N(x) and N(y)
533 names = availsToNameSet (map snd items2)
534 keep n = not (n `elemNameSet` names)
535 pruned_avails = filterAvails keep all_avails
536 hiding_prov = Imported [ImpSpec { is_decl = decl_spec, is_item = ImpAll }]
538 gres | want_hiding = gresFromAvails hiding_prov pruned_avails
539 | otherwise = concatMap (gresFromIE decl_spec) items2
541 return (Just (want_hiding, map fst items2), mkGlobalRdrEnv gres)
543 -- This environment is how we map names mentioned in the import
544 -- list to the actual Name they correspond to, and the name family
545 -- that the Name belongs to (the AvailInfo). The situation is
546 -- complicated by associated families, which introduce a three-level
547 -- hierachy, where class = grand parent, assoc family = parent, and
548 -- data constructors = children. The occ_env entries for associated
549 -- families needs to capture all this information; hence, we have the
550 -- third component of the environment that gives the class name (=
551 -- grand parent) in case of associated families.
553 -- This env will have entries for data constructors too,
554 -- they won't make any difference because naked entities like T
555 -- in an import list map to TcOccs, not VarOccs.
556 occ_env :: OccEnv (Name, -- the name
557 AvailInfo, -- the export item providing the name
558 Maybe Name) -- the parent of associated types
559 occ_env = mkOccEnv_C combine [ (nameOccName n, (n, a, Nothing))
560 | a <- all_avails, n <- availNames a]
562 -- we know that (1) there are at most entries for one name, (2) their
563 -- first component is identical, (3) they are for tys/cls, and (4) one
564 -- entry has the name in its parent position (the other doesn't)
565 combine (name, AvailTC p1 subs1, Nothing)
566 (_ , AvailTC p2 subs2, Nothing)
568 (parent, subs) = if p1 == name then (p2, subs1) else (p1, subs2)
570 (name, AvailTC name subs, Just parent)
571 combine x y = pprPanic "filterImports/combine" (ppr x $$ ppr y)
573 lookup_lie :: Bool -> LIE RdrName -> TcRn [(LIE Name, AvailInfo)]
574 lookup_lie opt_typeFamilies (L loc ieRdr)
576 stuff <- setSrcSpan loc $
577 case lookup_ie opt_typeFamilies ieRdr of
578 Failed err -> addErr err >> return []
579 Succeeded a -> return a
580 checkDodgyImport stuff
581 return [ (L loc ie, avail) | (ie,avail) <- stuff ]
583 -- Warn when importing T(..) if T was exported abstractly
584 checkDodgyImport stuff
585 | IEThingAll n <- ieRdr, (_, AvailTC _ [_]):_ <- stuff
586 = ifDOptM Opt_WarnDodgyImports (addWarn (dodgyImportWarn n))
587 -- NB. use the RdrName for reporting the warning
588 | IEThingAll {} <- ieRdr
589 = ifDOptM Opt_WarnMissingImportList $
590 addWarn (missingImportListItem ieRdr)
594 -- For each import item, we convert its RdrNames to Names,
595 -- and at the same time construct an AvailInfo corresponding
596 -- to what is actually imported by this item.
597 -- Returns Nothing on error.
598 -- We return a list here, because in the case of an import
599 -- item like C, if we are hiding, then C refers to *both* a
600 -- type/class and a data constructor. Moreover, when we import
601 -- data constructors of an associated family, we need separate
602 -- AvailInfos for the data constructors and the family (as they have
603 -- different parents). See the discussion at occ_env.
604 lookup_ie :: Bool -> IE RdrName -> MaybeErr Message [(IE Name,AvailInfo)]
605 lookup_ie opt_typeFamilies ie
606 = let bad_ie :: MaybeErr Message a
607 bad_ie = Failed (badImportItemErr iface decl_spec ie)
610 | isQual rdr = Failed (qualImportItemErr rdr)
611 | Just nm <- lookupOccEnv occ_env (rdrNameOcc rdr) = return nm
616 (name, avail, _) <- lookup_name n
617 return [(IEVar name, trimAvail avail name)]
620 (name, avail@(AvailTC name2 subs), mb_parent) <- lookup_name tc
622 -- non-associated ty/cls
623 Nothing -> return [(IEThingAll name, avail)]
625 Just parent -> return [(IEThingAll name,
626 AvailTC name2 (subs \\ [name])),
627 (IEThingAll name, AvailTC parent [name])]
630 | want_hiding -- hiding ( C )
631 -- Here the 'C' can be a data constructor
632 -- *or* a type/class, or even both
633 -> let tc_name = lookup_name tc
634 dc_name = lookup_name (setRdrNameSpace tc srcDataName)
636 case catMaybeErr [ tc_name, dc_name ] of
638 names -> return [mkIEThingAbs name | name <- names]
640 -> do nameAvail <- lookup_name tc
641 return [mkIEThingAbs nameAvail]
643 IEThingWith tc ns -> do
644 (name, AvailTC _ subnames, mb_parent) <- lookup_name tc
646 env = mkOccEnv [(nameOccName s, s) | s <- subnames]
647 mb_children = map (lookupOccEnv env . rdrNameOcc) ns
648 children <- if any isNothing mb_children
650 else return (catMaybes mb_children)
651 -- check for proper import of type families
652 when (not opt_typeFamilies && any isTyConName children) $
653 Failed (typeItemErr (head . filter isTyConName $ children)
654 (text "in import list"))
656 -- non-associated ty/cls
657 Nothing -> return [(IEThingWith name children,
658 AvailTC name (name:children))]
660 Just parent -> return [(IEThingWith name children,
661 AvailTC name children),
662 (IEThingWith name children,
663 AvailTC parent [name])]
665 _other -> Failed illegalImportItemErr
666 -- could be IEModuleContents, IEGroup, IEDoc, IEDocNamed
670 mkIEThingAbs (n, av, Nothing ) = (IEThingAbs n, trimAvail av n)
671 mkIEThingAbs (n, _, Just parent) = (IEThingAbs n, AvailTC parent [n])
674 catMaybeErr :: [MaybeErr err a] -> [a]
675 catMaybeErr ms = [ a | Succeeded a <- ms ]
678 %************************************************************************
680 \subsection{Import/Export Utils}
682 %************************************************************************
685 -- | make a 'GlobalRdrEnv' where all the elements point to the same
686 -- import declaration (useful for "hiding" imports, or imports with
688 gresFromAvails :: Provenance -> [AvailInfo] -> [GlobalRdrElt]
689 gresFromAvails prov avails
690 = concatMap (gresFromAvail (const prov)) avails
692 gresFromAvail :: (Name -> Provenance) -> AvailInfo -> [GlobalRdrElt]
693 gresFromAvail prov_fn avail
694 = [ GRE {gre_name = n,
695 gre_par = availParent n avail,
696 gre_prov = prov_fn n}
697 | n <- availNames avail ]
699 greAvail :: GlobalRdrElt -> AvailInfo
700 greAvail gre = mkUnitAvail (gre_name gre) (gre_par gre)
702 mkUnitAvail :: Name -> Parent -> AvailInfo
703 mkUnitAvail me (ParentIs p) = AvailTC p [me]
704 mkUnitAvail me NoParent | isTyConName me = AvailTC me [me]
705 | otherwise = Avail me
707 plusAvail :: GenAvailInfo Name -> GenAvailInfo Name -> GenAvailInfo Name
708 plusAvail (Avail n1) (Avail _) = Avail n1
709 plusAvail (AvailTC _ ns1) (AvailTC n2 ns2) = AvailTC n2 (ns1 `unionLists` ns2)
710 plusAvail a1 a2 = pprPanic "RnEnv.plusAvail" (hsep [ppr a1,ppr a2])
712 availParent :: Name -> AvailInfo -> Parent
713 availParent _ (Avail _) = NoParent
714 availParent n (AvailTC m _) | n == m = NoParent
715 | otherwise = ParentIs m
717 trimAvail :: AvailInfo -> Name -> AvailInfo
718 trimAvail (Avail n) _ = Avail n
719 trimAvail (AvailTC n ns) m = ASSERT( m `elem` ns) AvailTC n [m]
721 -- | filters 'AvailInfo's by the given predicate
722 filterAvails :: (Name -> Bool) -> [AvailInfo] -> [AvailInfo]
723 filterAvails keep avails = foldr (filterAvail keep) [] avails
725 -- | filters an 'AvailInfo' by the given predicate
726 filterAvail :: (Name -> Bool) -> AvailInfo -> [AvailInfo] -> [AvailInfo]
727 filterAvail keep ie rest =
729 Avail n | keep n -> ie : rest
732 let left = filter keep ns in
733 if null left then rest else AvailTC tc left : rest
735 -- | Given an import\/export spec, construct the appropriate 'GlobalRdrElt's.
736 gresFromIE :: ImpDeclSpec -> (LIE Name, AvailInfo) -> [GlobalRdrElt]
737 gresFromIE decl_spec (L loc ie, avail)
738 = gresFromAvail prov_fn avail
740 is_explicit = case ie of
741 IEThingAll name -> \n -> n == name
743 prov_fn name = Imported [imp_spec]
745 imp_spec = ImpSpec { is_decl = decl_spec, is_item = item_spec }
746 item_spec = ImpSome { is_explicit = is_explicit name, is_iloc = loc }
748 mkChildEnv :: [GlobalRdrElt] -> NameEnv [Name]
749 mkChildEnv gres = foldr add emptyNameEnv gres
751 add (GRE { gre_name = n, gre_par = ParentIs p }) env = extendNameEnv_Acc (:) singleton env p n
754 findChildren :: NameEnv [Name] -> Name -> [Name]
755 findChildren env n = lookupNameEnv env n `orElse` []
758 ---------------------------------------
761 All this AvailEnv stuff is hardly used; only in a very small
762 part of RnNames. Todo: remove?
763 ---------------------------------------
766 type AvailEnv = NameEnv AvailInfo -- Maps a Name to the AvailInfo that contains it
768 emptyAvailEnv :: AvailEnv
769 emptyAvailEnv = emptyNameEnv
772 unitAvailEnv :: AvailInfo -> AvailEnv
773 unitAvailEnv a = unitNameEnv (availName a) a
775 plusAvailEnv :: AvailEnv -> AvailEnv -> AvailEnv
776 plusAvailEnv = plusNameEnv_C plusAvail
778 availEnvElts :: AvailEnv -> [AvailInfo]
779 availEnvElts = nameEnvElts
782 addAvail :: AvailEnv -> AvailInfo -> AvailEnv
783 addAvail avails avail = extendNameEnv_C plusAvail avails (availName avail) avail
785 mkAvailEnv :: [AvailInfo] -> AvailEnv
786 -- 'avails' may have several items with the same availName
787 -- E.g import Ix( Ix(..), index )
788 -- will give Ix(Ix,index,range) and Ix(index)
789 -- We want to combine these; addAvail does that
790 mkAvailEnv avails = foldl addAvail emptyAvailEnv avails
792 -- After combining the avails, we need to ensure that the parent name is the
793 -- first entry in the list of subnames, if it is included at all. (Subsequent
794 -- functions rely on that.)
795 normaliseAvail :: AvailInfo -> AvailInfo
796 normaliseAvail avail@(Avail _) = avail
797 normaliseAvail (AvailTC name subs) = AvailTC name subs'
799 subs' = if name `elem` subs then name : (delete name subs) else subs
801 -- | combines 'AvailInfo's from the same family
802 nubAvails :: [AvailInfo] -> [AvailInfo]
803 nubAvails avails = map normaliseAvail . nameEnvElts . mkAvailEnv $ avails
807 %************************************************************************
809 \subsection{Export list processing}
811 %************************************************************************
813 Processing the export list.
815 You might think that we should record things that appear in the export
816 list as ``occurrences'' (using @addOccurrenceName@), but you'd be
817 wrong. We do check (here) that they are in scope, but there is no
818 need to slurp in their actual declaration (which is what
819 @addOccurrenceName@ forces).
821 Indeed, doing so would big trouble when compiling @PrelBase@, because
822 it re-exports @GHC@, which includes @takeMVar#@, whose type includes
823 @ConcBase.StateAndSynchVar#@, and so on...
826 type ExportAccum -- The type of the accumulating parameter of
827 -- the main worker function in rnExports
828 = ([LIE Name], -- Export items with Names
829 ExportOccMap, -- Tracks exported occurrence names
830 [AvailInfo]) -- The accumulated exported stuff
833 emptyExportAccum :: ExportAccum
834 emptyExportAccum = ([], emptyOccEnv, [])
836 type ExportOccMap = OccEnv (Name, IE RdrName)
837 -- Tracks what a particular exported OccName
838 -- in an export list refers to, and which item
839 -- it came from. It's illegal to export two distinct things
840 -- that have the same occurrence name
842 rnExports :: Bool -- False => no 'module M(..) where' header at all
843 -> Maybe [LIE RdrName] -- Nothing => no explicit export list
847 -- Complains if two distinct exports have same OccName
848 -- Warns about identical exports.
849 -- Complains about exports items not in scope
851 rnExports explicit_mod exports
852 tcg_env@(TcGblEnv { tcg_mod = this_mod,
853 tcg_rdr_env = rdr_env,
854 tcg_imports = imports })
856 -- If the module header is omitted altogether, then behave
857 -- as if the user had written "module Main(main) where..."
858 -- EXCEPT in interactive mode, when we behave as if he had
859 -- written "module Main where ..."
860 -- Reason: don't want to complain about 'main' not in scope
861 -- in interactive mode
864 | explicit_mod = exports
865 | ghcLink dflags == LinkInMemory = Nothing
866 | otherwise = Just ([noLoc (IEVar main_RDR_Unqual)])
867 -- ToDo: the 'noLoc' here is unhelpful if 'main'
868 -- turns out to be out of scope
870 ; (rn_exports, avails) <- exports_from_avail real_exports rdr_env imports this_mod
871 ; let final_avails = nubAvails avails -- Combine families
873 ; return (tcg_env { tcg_exports = final_avails,
874 tcg_rn_exports = case tcg_rn_exports tcg_env of
876 Just _ -> rn_exports,
877 tcg_dus = tcg_dus tcg_env `plusDU`
878 usesOnly (availsToNameSet final_avails) }) }
880 exports_from_avail :: Maybe [LIE RdrName]
881 -- Nothing => no explicit export list
885 -> RnM (Maybe [LIE Name], [AvailInfo])
887 exports_from_avail Nothing rdr_env _imports _this_mod
888 = -- The same as (module M) where M is the current module name,
889 -- so that's how we handle it.
891 avails = [ greAvail gre | gre <- globalRdrEnvElts rdr_env,
894 return (Nothing, avails)
896 exports_from_avail (Just rdr_items) rdr_env imports this_mod
897 = do (ie_names, _, exports) <- foldlM do_litem emptyExportAccum rdr_items
899 return (Just ie_names, exports)
901 do_litem :: ExportAccum -> LIE RdrName -> RnM ExportAccum
902 do_litem acc lie = setSrcSpan (getLoc lie) (exports_from_item acc lie)
904 kids_env :: NameEnv [Name] -- Maps a parent to its in-scope children
905 kids_env = mkChildEnv (globalRdrEnvElts rdr_env)
907 imported_modules = [ qual_name
908 | xs <- moduleEnvElts $ imp_mods imports,
909 (qual_name, _, _) <- xs ]
911 exports_from_item :: ExportAccum -> LIE RdrName -> RnM ExportAccum
912 exports_from_item acc@(ie_names, occs, exports)
913 (L loc ie@(IEModuleContents mod))
914 | let earlier_mods = [ mod | (L _ (IEModuleContents mod)) <- ie_names ]
915 , mod `elem` earlier_mods -- Duplicate export of M
916 = do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
917 warnIf warn_dup_exports (dupModuleExport mod) ;
921 = do { implicit_prelude <- xoptM Opt_ImplicitPrelude
922 ; warnDodgyExports <- doptM Opt_WarnDodgyExports
923 ; let { exportValid = (mod `elem` imported_modules)
924 || (moduleName this_mod == mod)
925 ; gres = filter (isModuleExported implicit_prelude mod)
926 (globalRdrEnvElts rdr_env)
927 ; names = map gre_name gres
930 ; checkErr exportValid (moduleNotImported mod)
931 ; warnIf (warnDodgyExports && exportValid && null gres) (nullModuleExport mod)
933 ; addUsedRdrNames (concat [ [mkRdrQual mod occ, mkRdrUnqual occ]
934 | occ <- map nameOccName names ])
935 -- The qualified and unqualified version of all of
936 -- these names are, in effect, used by this export
938 ; occs' <- check_occs ie occs names
939 -- This check_occs not only finds conflicts
940 -- between this item and others, but also
941 -- internally within this item. That is, if
942 -- 'M.x' is in scope in several ways, we'll have
943 -- several members of mod_avails with the same
945 ; return (L loc (IEModuleContents mod) : ie_names,
946 occs', map greAvail gres ++ exports) }
948 exports_from_item acc@(lie_names, occs, exports) (L loc ie)
950 = do new_ie <- lookup_doc_ie ie
951 return (L loc new_ie : lie_names, occs, exports)
954 = do (new_ie, avail) <- lookup_ie ie
955 if isUnboundName (ieName new_ie)
956 then return acc -- Avoid error cascade
959 occs' <- check_occs ie occs (availNames avail)
961 return (L loc new_ie : lie_names, occs', avail : exports)
964 lookup_ie :: IE RdrName -> RnM (IE Name, AvailInfo)
965 lookup_ie (IEVar rdr)
966 = do gre <- lookupGreRn rdr
967 return (IEVar (gre_name gre), greAvail gre)
969 lookup_ie (IEThingAbs rdr)
970 = do gre <- lookupGreRn rdr
971 let name = gre_name gre
973 NoParent -> return (IEThingAbs name,
975 ParentIs p -> return (IEThingAbs name,
978 lookup_ie ie@(IEThingAll rdr)
979 = do name <- lookupGlobalOccRn rdr
980 let kids = findChildren kids_env name
981 mkKidRdrName = case isQual_maybe rdr of
982 Nothing -> mkRdrUnqual
983 Just (modName, _) -> mkRdrQual modName
984 addUsedRdrNames $ map (mkKidRdrName . nameOccName) kids
985 warnDodgyExports <- doptM Opt_WarnDodgyExports
988 then when warnDodgyExports $ addWarn (dodgyExportWarn name)
989 else -- This occurs when you export T(..), but
990 -- only import T abstractly, or T is a synonym.
991 addErr (exportItemErr ie)
993 return (IEThingAll name, AvailTC name (name:kids))
995 lookup_ie ie@(IEThingWith rdr sub_rdrs)
996 = do name <- lookupGlobalOccRn rdr
997 if isUnboundName name
998 then return (IEThingWith name [], AvailTC name [name])
1000 let env = mkOccEnv [ (nameOccName s, s)
1001 | s <- findChildren kids_env name ]
1002 mb_names = map (lookupOccEnv env . rdrNameOcc) sub_rdrs
1003 if any isNothing mb_names
1004 then do addErr (exportItemErr ie)
1005 return (IEThingWith name [], AvailTC name [name])
1006 else do let names = catMaybes mb_names
1007 optTyFam <- xoptM Opt_TypeFamilies
1008 when (not optTyFam && any isTyConName names) $
1009 addErr (typeItemErr ( head
1010 . filter isTyConName
1012 (text "in export list"))
1013 return (IEThingWith name names, AvailTC name (name:names))
1015 lookup_ie _ = panic "lookup_ie" -- Other cases covered earlier
1018 lookup_doc_ie :: IE RdrName -> RnM (IE Name)
1019 lookup_doc_ie (IEGroup lev doc) = do rn_doc <- rnHsDoc doc
1020 return (IEGroup lev rn_doc)
1021 lookup_doc_ie (IEDoc doc) = do rn_doc <- rnHsDoc doc
1022 return (IEDoc rn_doc)
1023 lookup_doc_ie (IEDocNamed str) = return (IEDocNamed str)
1024 lookup_doc_ie _ = panic "lookup_doc_ie" -- Other cases covered earlier
1027 isDoc :: IE RdrName -> Bool
1028 isDoc (IEDoc _) = True
1029 isDoc (IEDocNamed _) = True
1030 isDoc (IEGroup _ _) = True
1033 -------------------------------
1034 isModuleExported :: Bool -> ModuleName -> GlobalRdrElt -> Bool
1035 -- True if the thing is in scope *both* unqualified, *and* with qualifier M
1036 isModuleExported implicit_prelude mod (GRE { gre_name = name, gre_prov = prov })
1037 | implicit_prelude && isBuiltInSyntax name = False
1038 -- Optimisation: filter out names for built-in syntax
1039 -- They just clutter up the environment (esp tuples), and the parser
1040 -- will generate Exact RdrNames for them, so the cluttered
1041 -- envt is no use. To avoid doing this filter all the time,
1042 -- we use -XNoImplicitPrelude as a clue that the filter is
1043 -- worth while. Really, it's only useful for GHC.Base and GHC.Tuple.
1045 -- It's worth doing because it makes the environment smaller for
1046 -- every module that imports the Prelude
1049 LocalDef | Just name_mod <- nameModule_maybe name
1050 -> moduleName name_mod == mod
1051 | otherwise -> False
1052 Imported is -> any unQualSpecOK is && any (qualSpecOK mod) is
1054 -------------------------------
1055 check_occs :: IE RdrName -> ExportOccMap -> [Name] -> RnM ExportOccMap
1056 check_occs ie occs names
1057 = foldlM check occs names
1060 = case lookupOccEnv occs name_occ of
1061 Nothing -> return (extendOccEnv occs name_occ (name, ie))
1064 | name == name' -- Duplicate export
1065 -- But we don't want to warn if the same thing is exported
1066 -- by two different module exports. See ticket #4478.
1067 -> if diffModules ie ie'
1070 { warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
1071 warnIf warn_dup_exports (dupExportWarn name_occ ie ie') ;
1074 | otherwise -- Same occ name but different names: an error
1075 -> do { global_env <- getGlobalRdrEnv ;
1076 addErr (exportClashErr global_env name' name ie' ie) ;
1079 name_occ = nameOccName name
1080 -- True if the two IE RdrName are different module exports.
1081 diffModules (IEModuleContents n1) (IEModuleContents n2) = n1 /= n2
1082 diffModules _ _ = False
1085 %*********************************************************
1087 \subsection{Deprecations}
1089 %*********************************************************
1092 finishWarnings :: DynFlags -> Maybe WarningTxt
1093 -> TcGblEnv -> RnM TcGblEnv
1094 -- (a) Report usage of imports that are deprecated or have other warnings
1095 -- (b) If the whole module is warned about or deprecated, update tcg_warns
1096 -- All this happens only once per module
1097 finishWarnings dflags mod_warn tcg_env
1098 = do { (eps,hpt) <- getEpsAndHpt
1099 ; ifDOptM Opt_WarnWarningsDeprecations $
1100 mapM_ (check hpt (eps_PIT eps)) all_gres
1101 -- By this time, typechecking is complete,
1102 -- so the PIT is fully populated
1104 -- Deal with a module deprecation; it overrides all existing warns
1105 ; let new_warns = case mod_warn of
1106 Just txt -> WarnAll txt
1107 Nothing -> tcg_warns tcg_env
1108 ; return (tcg_env { tcg_warns = new_warns }) }
1110 used_names = allUses (tcg_dus tcg_env)
1111 -- Report on all deprecated uses; hence allUses
1112 all_gres = globalRdrEnvElts (tcg_rdr_env tcg_env)
1114 check hpt pit gre@(GRE {gre_name = name, gre_prov = Imported (imp_spec:_)})
1115 | name `elemNameSet` used_names
1116 , Just deprec_txt <- lookupImpDeprec dflags hpt pit gre
1117 = addWarnAt (importSpecLoc imp_spec)
1118 (sep [ptext (sLit "In the use of") <+>
1119 pprNonVarNameSpace (occNameSpace (nameOccName name)) <+>
1121 (parens imp_msg) <> colon,
1124 name_mod = ASSERT2( isExternalName name, ppr name ) nameModule name
1125 imp_mod = importSpecModule imp_spec
1126 imp_msg = ptext (sLit "imported from") <+> ppr imp_mod <> extra
1127 extra | imp_mod == moduleName name_mod = empty
1128 | otherwise = ptext (sLit ", but defined in") <+> ppr name_mod
1130 check _ _ _ = return () -- Local, or not used, or not deprectated
1131 -- The Imported pattern-match: don't deprecate locally defined names
1132 -- For a start, we may be exporting a deprecated thing
1133 -- Also we may use a deprecated thing in the defn of another
1134 -- deprecated things. We may even use a deprecated thing in
1135 -- the defn of a non-deprecated thing, when changing a module's
1138 lookupImpDeprec :: DynFlags -> HomePackageTable -> PackageIfaceTable
1139 -> GlobalRdrElt -> Maybe WarningTxt
1140 -- The name is definitely imported, so look in HPT, PIT
1141 lookupImpDeprec dflags hpt pit gre
1142 = case lookupIfaceByModule dflags hpt pit mod of
1143 Just iface -> mi_warn_fn iface name `mplus` -- Bleat if the thing, *or
1145 ParentIs p -> mi_warn_fn iface p -- its parent*, is warn'd
1148 Nothing -> Nothing -- See Note [Used names with interface not loaded]
1151 mod = ASSERT2( isExternalName name, ppr name ) nameModule name
1154 Note [Used names with interface not loaded]
1155 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1156 By now all the interfaces should have been loaded,
1157 because reportDeprecations happens after typechecking.
1158 However, it's still (just) possible to to find a used
1159 Name whose interface hasn't been loaded:
1161 a) It might be a WiredInName; in that case we may not load
1162 its interface (although we could).
1164 b) It might be GHC.Real.fromRational, or GHC.Num.fromInteger
1165 These are seen as "used" by the renamer (if -XRebindableSyntax)
1166 is on), but the typechecker may discard their uses
1167 if in fact the in-scope fromRational is GHC.Read.fromRational,
1168 (see tcPat.tcOverloadedLit), and the typechecker sees that the type
1169 is fixed, say, to GHC.Base.Float (see Inst.lookupSimpleInst).
1170 In that obscure case it won't force the interface in.
1172 In both cases we simply don't permit deprecations;
1173 this is, after all, wired-in stuff.
1176 %*********************************************************
1178 \subsection{Unused names}
1180 %*********************************************************
1183 reportUnusedNames :: Maybe [LIE RdrName] -- Export list
1184 -> TcGblEnv -> RnM ()
1185 reportUnusedNames _export_decls gbl_env
1186 = do { traceRn ((text "RUN") <+> (ppr (tcg_dus gbl_env)))
1187 ; warnUnusedImportDecls gbl_env
1188 ; warnUnusedTopBinds unused_locals }
1190 used_names :: NameSet
1191 used_names = findUses (tcg_dus gbl_env) emptyNameSet
1192 -- NB: currently, if f x = g, we only treat 'g' as used if 'f' is used
1195 -- Collect the defined names from the in-scope environment
1196 defined_names :: [GlobalRdrElt]
1197 defined_names = globalRdrEnvElts (tcg_rdr_env gbl_env)
1199 -- Note that defined_and_used, defined_but_not_used
1200 -- are both [GRE]; that's why we need defined_and_used
1201 -- rather than just used_names
1202 _defined_and_used, defined_but_not_used :: [GlobalRdrElt]
1203 (_defined_and_used, defined_but_not_used)
1204 = partition (gre_is_used used_names) defined_names
1206 kids_env = mkChildEnv defined_names
1207 -- This is done in mkExports too; duplicated work
1209 gre_is_used :: NameSet -> GlobalRdrElt -> Bool
1210 gre_is_used used_names (GRE {gre_name = name})
1211 = name `elemNameSet` used_names
1212 || any (`elemNameSet` used_names) (findChildren kids_env name)
1213 -- A use of C implies a use of T,
1214 -- if C was brought into scope by T(..) or T(C)
1216 -- Filter out the ones that are
1217 -- (a) defined in this module, and
1218 -- (b) not defined by a 'deriving' clause
1219 -- The latter have an Internal Name, so we can filter them out easily
1220 unused_locals :: [GlobalRdrElt]
1221 unused_locals = filter is_unused_local defined_but_not_used
1222 is_unused_local :: GlobalRdrElt -> Bool
1223 is_unused_local gre = isLocalGRE gre && isExternalName (gre_name gre)
1226 %*********************************************************
1228 \subsection{Unused imports}
1230 %*********************************************************
1232 This code finds which import declarations are unused. The
1233 specification and implementation notes are here:
1234 http://hackage.haskell.org/trac/ghc/wiki/Commentary/Compiler/UnusedImports
1237 type ImportDeclUsage
1238 = ( LImportDecl Name -- The import declaration
1239 , [AvailInfo] -- What *is* used (normalised)
1240 , [Name] ) -- What is imported but *not* used
1244 warnUnusedImportDecls :: TcGblEnv -> RnM ()
1245 warnUnusedImportDecls gbl_env
1246 = do { uses <- readMutVar (tcg_used_rdrnames gbl_env)
1247 ; let imports = filter explicit_import (tcg_rn_imports gbl_env)
1248 rdr_env = tcg_rdr_env gbl_env
1250 ; let usage :: [ImportDeclUsage]
1251 usage = findImportUsage imports rdr_env (Set.elems uses)
1253 ; ifDOptM Opt_WarnUnusedImports $
1254 mapM_ warnUnusedImport usage
1256 ; ifDOptM Opt_D_dump_minimal_imports $
1257 printMinimalImports usage }
1259 explicit_import (L loc _) = isGoodSrcSpan loc
1260 -- Filter out the implicit Prelude import
1261 -- which we do not want to bleat about
1265 findImportUsage :: [LImportDecl Name]
1268 -> [ImportDeclUsage]
1270 type ImportMap = Map SrcLoc [AvailInfo]
1271 -- The intermediate data struture records, for each import
1272 -- declaration, what stuff brought into scope by that
1273 -- declaration is actually used in the module.
1275 -- The SrcLoc is the location of the start
1276 -- of a particular 'import' declaration
1278 -- The AvailInfos are the things imported from that decl
1279 -- (just a list, not normalised)
1281 findImportUsage imports rdr_env rdrs
1282 = map unused_decl imports
1284 import_usage :: ImportMap
1285 import_usage = foldr (addUsedRdrName rdr_env) Map.empty rdrs
1287 unused_decl decl@(L loc (ImportDecl { ideclHiding = imps }))
1288 = (decl, nubAvails used_avails, unused_imps)
1290 used_avails = Map.lookup (srcSpanStart loc) import_usage `orElse` []
1291 dont_report_as_unused = foldr add emptyNameSet used_avails
1292 add (Avail n) s = s `addOneToNameSet` n
1293 add (AvailTC n ns) s = s `addListToNameSet` (n:ns)
1294 -- If you use 'signum' from Num, then the user may well have
1295 -- imported Num(signum). We don't want to complain that
1296 -- Num is not itself mentioned. Hence adding 'n' as
1297 -- well to the list of of "don't report if unused" names
1299 unused_imps = case imps of
1300 Just (False, imp_ies) -> nameSetToList unused_imps
1302 imp_names = mkNameSet (concatMap (ieNames . unLoc) imp_ies)
1303 unused_imps = imp_names `minusNameSet` dont_report_as_unused
1305 _other -> [] -- No explicit import list => no unused-name list
1307 addUsedRdrName :: GlobalRdrEnv -> RdrName -> ImportMap -> ImportMap
1308 -- For a used RdrName, find all the import decls that brought
1309 -- it into scope; choose one of them (bestImport), and record
1310 -- the RdrName in that import decl's entry in the ImportMap
1311 addUsedRdrName rdr_env rdr imp_map
1312 | [gre] <- lookupGRE_RdrName rdr rdr_env
1313 , Imported imps <- gre_prov gre
1314 = add_imp gre (bestImport imps) imp_map
1318 add_imp :: GlobalRdrElt -> ImportSpec -> ImportMap -> ImportMap
1319 add_imp gre (ImpSpec { is_decl = imp_decl_spec }) imp_map
1320 = Map.insertWith add decl_loc [avail] imp_map
1322 add _ avails = avail : avails -- add is really just a specialised (++)
1323 decl_loc = srcSpanStart (is_dloc imp_decl_spec)
1325 avail = case gre_par gre of
1326 ParentIs p -> AvailTC p [name]
1327 NoParent | isTyConName name -> AvailTC name [name]
1328 | otherwise -> Avail name
1330 bestImport :: [ImportSpec] -> ImportSpec
1332 = case partition isImpAll iss of
1333 ([], imp_somes) -> textuallyFirst imp_somes
1334 (imp_alls, _) -> textuallyFirst imp_alls
1336 textuallyFirst :: [ImportSpec] -> ImportSpec
1337 textuallyFirst iss = case sortWith (is_dloc . is_decl) iss of
1338 [] -> pprPanic "textuallyFirst" (ppr iss)
1341 isImpAll :: ImportSpec -> Bool
1342 isImpAll (ImpSpec { is_item = ImpAll }) = True
1343 isImpAll _other = False
1347 warnUnusedImport :: ImportDeclUsage -> RnM ()
1348 warnUnusedImport (L loc decl, used, unused)
1349 | Just (False,[]) <- ideclHiding decl
1350 = return () -- Do not warn for 'import M()'
1351 | null used = addWarnAt loc msg1 -- Nothing used; drop entire decl
1352 | null unused = return () -- Everything imported is used; nop
1353 | otherwise = addWarnAt loc msg2 -- Some imports are unused
1355 msg1 = vcat [pp_herald <+> quotes pp_mod <+> pp_not_used,
1356 nest 2 (ptext (sLit "except perhaps to import instances from")
1358 ptext (sLit "To import instances alone, use:")
1359 <+> ptext (sLit "import") <+> pp_mod <> parens empty ]
1360 msg2 = sep [pp_herald <+> quotes (pprWithCommas ppr unused),
1361 text "from module" <+> quotes pp_mod <+> pp_not_used]
1362 pp_herald = text "The import of"
1363 pp_mod = ppr (unLoc (ideclName decl))
1364 pp_not_used = text "is redundant"
1367 To print the minimal imports we walk over the user-supplied import
1368 decls, and simply trim their import lists. NB that
1370 * We do *not* change the 'qualified' or 'as' parts!
1372 * We do not disard a decl altogether; we might need instances
1373 from it. Instead we just trim to an empty import list
1376 printMinimalImports :: [ImportDeclUsage] -> RnM ()
1377 printMinimalImports imports_w_usage
1378 = do { imports' <- mapM mk_minimal imports_w_usage
1379 ; this_mod <- getModule
1381 do { h <- openFile (mkFilename this_mod) WriteMode
1382 ; printForUser h neverQualify (vcat (map ppr imports')) }
1383 -- The neverQualify is important. We are printing Names
1384 -- but they are in the context of an 'import' decl, and
1385 -- we never qualify things inside there
1386 -- E.g. import Blag( f, b )
1387 -- not import Blag( Blag.f, Blag.g )!
1390 mkFilename this_mod = moduleNameString (moduleName this_mod) ++ ".imports"
1392 mk_minimal (L l decl, used, unused)
1394 , Just (False, _) <- ideclHiding decl
1397 = do { let ImportDecl { ideclName = L _ mod_name
1398 , ideclSource = is_boot
1399 , ideclPkgQual = mb_pkg } = decl
1400 ; iface <- loadSrcInterface doc mod_name is_boot mb_pkg
1401 ; let lies = map (L l) (concatMap (to_ie iface) used)
1402 ; return (L l (decl { ideclHiding = Just (False, lies) })) }
1404 doc = text "Compute minimal imports for" <+> ppr decl
1406 to_ie :: ModIface -> AvailInfo -> [IE Name]
1407 -- The main trick here is that if we're importing all the constructors
1408 -- we want to say "T(..)", but if we're importing only a subset we want
1409 -- to say "T(A,B,C)". So we have to find out what the module exports.
1412 to_ie _ (AvailTC n [m])
1413 | n==m = [IEThingAbs n]
1414 to_ie iface (AvailTC n ns)
1415 = case [xs | (m,as) <- mi_exports iface
1417 , AvailTC x xs <- as
1418 , x == nameOccName n
1419 , x `elem` xs -- Note [Partial export]
1421 [xs] | all_used xs -> [IEThingAll n]
1422 | otherwise -> [IEThingWith n (filter (/= n) ns)]
1423 _other -> (map IEVar ns)
1425 all_used avail_occs = all (`elem` map nameOccName ns) avail_occs
1426 n_mod = ASSERT( isExternalName n ) nameModule n
1429 Note [Partial export]
1430 ~~~~~~~~~~~~~~~~~~~~~
1433 module A( op ) where
1441 Then the minimal import for module B is
1445 which we would usually generate if C was exported from B. Hence
1446 the (x `elem` xs) test when deciding what to generate.
1449 %************************************************************************
1453 %************************************************************************
1456 qualImportItemErr :: RdrName -> SDoc
1457 qualImportItemErr rdr
1458 = hang (ptext (sLit "Illegal qualified name in import item:"))
1461 badImportItemErr :: ModIface -> ImpDeclSpec -> IE RdrName -> SDoc
1462 badImportItemErr iface decl_spec ie
1463 = sep [ptext (sLit "Module"), quotes (ppr (is_mod decl_spec)), source_import,
1464 ptext (sLit "does not export"), quotes (ppr ie)]
1466 source_import | mi_boot iface = ptext (sLit "(hi-boot interface)")
1469 illegalImportItemErr :: SDoc
1470 illegalImportItemErr = ptext (sLit "Illegal import item")
1472 dodgyImportWarn :: RdrName -> SDoc
1473 dodgyImportWarn item = dodgyMsg (ptext (sLit "import")) item
1474 dodgyExportWarn :: Name -> SDoc
1475 dodgyExportWarn item = dodgyMsg (ptext (sLit "export")) item
1477 dodgyMsg :: OutputableBndr n => SDoc -> n -> SDoc
1479 = sep [ ptext (sLit "The") <+> kind <+> ptext (sLit "item") <+> quotes (ppr (IEThingAll tc))
1480 <+> ptext (sLit "suggests that"),
1481 quotes (ppr tc) <+> ptext (sLit "has (in-scope) constructors or class methods,"),
1482 ptext (sLit "but it has none") ]
1484 exportItemErr :: IE RdrName -> SDoc
1485 exportItemErr export_item
1486 = sep [ ptext (sLit "The export item") <+> quotes (ppr export_item),
1487 ptext (sLit "attempts to export constructors or class methods that are not visible here") ]
1489 typeItemErr :: Name -> SDoc -> SDoc
1490 typeItemErr name wherestr
1491 = sep [ ptext (sLit "Using 'type' tag on") <+> quotes (ppr name) <+> wherestr,
1492 ptext (sLit "Use -XTypeFamilies to enable this extension") ]
1494 exportClashErr :: GlobalRdrEnv -> Name -> Name -> IE RdrName -> IE RdrName
1496 exportClashErr global_env name1 name2 ie1 ie2
1497 = vcat [ ptext (sLit "Conflicting exports for") <+> quotes (ppr occ) <> colon
1498 , ppr_export ie1' name1'
1499 , ppr_export ie2' name2' ]
1501 occ = nameOccName name1
1502 ppr_export ie name = nest 2 (quotes (ppr ie) <+> ptext (sLit "exports") <+>
1503 quotes (ppr name) <+> pprNameProvenance (get_gre name))
1505 -- get_gre finds a GRE for the Name, so that we can show its provenance
1507 = case lookupGRE_Name global_env name of
1509 [] -> pprPanic "exportClashErr" (ppr name)
1510 get_loc name = greSrcSpan (get_gre name)
1511 (name1', ie1', name2', ie2') = if get_loc name1 < get_loc name2
1512 then (name1, ie1, name2, ie2)
1513 else (name2, ie2, name1, ie1)
1515 -- the SrcSpan that pprNameProvenance prints out depends on whether
1516 -- the Name is defined locally or not: for a local definition the
1517 -- definition site is used, otherwise the location of the import
1518 -- declaration. We want to sort the export locations in
1519 -- exportClashErr by this SrcSpan, we need to extract it:
1520 greSrcSpan :: GlobalRdrElt -> SrcSpan
1522 | Imported (is:_) <- gre_prov gre = is_dloc (is_decl is)
1523 | otherwise = name_span
1525 name_span = nameSrcSpan (gre_name gre)
1527 addDupDeclErr :: [Name] -> TcRn ()
1529 = panic "addDupDeclErr: empty list"
1530 addDupDeclErr names@(name : _)
1531 = addErrAt (getSrcSpan (last sorted_names)) $
1532 -- Report the error at the later location
1533 vcat [ptext (sLit "Multiple declarations of") <+> quotes (ppr name),
1534 ptext (sLit "Declared at:") <+> vcat (map (ppr . nameSrcLoc) sorted_names)]
1536 sorted_names = sortWith nameSrcLoc names
1538 dupExportWarn :: OccName -> IE RdrName -> IE RdrName -> SDoc
1539 dupExportWarn occ_name ie1 ie2
1540 = hsep [quotes (ppr occ_name),
1541 ptext (sLit "is exported by"), quotes (ppr ie1),
1542 ptext (sLit "and"), quotes (ppr ie2)]
1544 dupModuleExport :: ModuleName -> SDoc
1546 = hsep [ptext (sLit "Duplicate"),
1547 quotes (ptext (sLit "Module") <+> ppr mod),
1548 ptext (sLit "in export list")]
1550 moduleNotImported :: ModuleName -> SDoc
1551 moduleNotImported mod
1552 = ptext (sLit "The export item `module") <+> ppr mod <>
1553 ptext (sLit "' is not imported")
1555 nullModuleExport :: ModuleName -> SDoc
1556 nullModuleExport mod
1557 = ptext (sLit "The export item `module") <+> ppr mod <> ptext (sLit "' exports nothing")
1559 missingImportListWarn :: ModuleName -> SDoc
1560 missingImportListWarn mod
1561 = ptext (sLit "The module") <+> quotes (ppr mod) <+> ptext (sLit "does not have an explicit import list")
1563 missingImportListItem :: IE RdrName -> SDoc
1564 missingImportListItem ie
1565 = ptext (sLit "The import item") <+> quotes (ppr ie) <+> ptext (sLit "does not have an explicit import list")
1567 moduleWarn :: ModuleName -> WarningTxt -> SDoc
1568 moduleWarn mod (WarningTxt txt)
1569 = sep [ ptext (sLit "Module") <+> quotes (ppr mod) <> ptext (sLit ":"),
1570 nest 2 (vcat (map ppr txt)) ]
1571 moduleWarn mod (DeprecatedTxt txt)
1572 = sep [ ptext (sLit "Module") <+> quotes (ppr mod)
1573 <+> ptext (sLit "is deprecated:"),
1574 nest 2 (vcat (map ppr txt)) ]
1576 implicitPreludeWarn :: SDoc
1578 = ptext (sLit "Module `Prelude' implicitly imported")
1580 packageImportErr :: SDoc
1582 = ptext (sLit "Package-qualified imports are not enabled; use -XPackageImports")