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, find )
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 () -- Explicit import list
116 _ | implicit_prelude -> return ()
117 | qual_only -> return ()
118 | otherwise -> ifDOptM Opt_WarnMissingImportList $
119 addWarn (missingImportListWarn imp_mod_name)
121 iface <- loadSrcInterface doc imp_mod_name want_boot mb_pkg
123 -- Compiler sanity check: if the import didn't say
124 -- {-# SOURCE #-} we should not get a hi-boot file
125 WARN( not want_boot && mi_boot iface, ppr imp_mod_name ) (do
127 -- Issue a user warning for a redundant {- SOURCE -} import
128 -- NB that we arrange to read all the ordinary imports before
129 -- any of the {- SOURCE -} imports.
131 -- in --make and GHCi, the compilation manager checks for this,
132 -- and indeed we shouldn't do it here because the existence of
133 -- the non-boot module depends on the compilation order, which
134 -- is not deterministic. The hs-boot test can show this up.
136 warnIf (want_boot && not (mi_boot iface) && isOneShot (ghcMode dflags))
137 (warnRedundantSourceImport imp_mod_name)
140 imp_mod = mi_module iface
141 warns = mi_warns iface
142 orph_iface = mi_orphan iface
143 has_finsts = mi_finsts iface
146 filtered_exports = filter not_this_mod (mi_exports iface)
147 not_this_mod (mod,_) = mod /= this_mod
148 -- If the module exports anything defined in this module, just
149 -- ignore it. Reason: otherwise it looks as if there are two
150 -- local definition sites for the thing, and an error gets
151 -- reported. Easiest thing is just to filter them out up
152 -- front. This situation only arises if a module imports
153 -- 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.
166 qual_mod_name = case as_mod of
167 Nothing -> imp_mod_name
168 Just another_name -> another_name
169 imp_spec = ImpDeclSpec { is_mod = imp_mod_name, is_qual = qual_only,
170 is_dloc = loc, is_as = qual_mod_name }
172 -- Get the total exports from this module
173 total_avails <- ifaceExportNames filtered_exports
175 -- filter the imports according to the import declaration
176 (new_imp_details, gbl_env) <-
177 filterImports iface imp_spec imp_details total_avails
182 -- Compute new transitive dependencies
184 orphans | orph_iface = ASSERT( not (imp_mod `elem` dep_orphs deps) )
185 imp_mod : dep_orphs deps
186 | otherwise = dep_orphs deps
188 finsts | has_finsts = ASSERT( not (imp_mod `elem` dep_finsts deps) )
189 imp_mod : dep_finsts deps
190 | otherwise = dep_finsts deps
192 pkg = modulePackageId (mi_module iface)
194 (dependent_mods, dependent_pkgs)
195 | pkg == thisPackage dflags =
196 -- Imported module is from the home package
197 -- Take its dependent modules and add imp_mod itself
198 -- Take its dependent packages unchanged
200 -- NB: (dep_mods deps) might include a hi-boot file
201 -- for the module being compiled, CM. Do *not* filter
202 -- this out (as we used to), because when we've
203 -- finished dealing with the direct imports we want to
204 -- know if any of them depended on CM.hi-boot, in
205 -- which case we should do the hi-boot consistency
206 -- check. See LoadIface.loadHiBootInterface
207 ((imp_mod_name, want_boot) : dep_mods deps, dep_pkgs deps)
210 -- Imported module is from another package
211 -- Dump the dependent modules
212 -- Add the package imp_mod comes from to the dependent packages
213 ASSERT2( not (pkg `elem` dep_pkgs deps), ppr pkg <+> ppr (dep_pkgs deps) )
214 ([], pkg : dep_pkgs deps)
216 -- True <=> import M ()
217 import_all = case imp_details of
218 Just (is_hiding, ls) -> not is_hiding && null ls
221 imports = ImportAvails {
222 imp_mods = unitModuleEnv imp_mod [(qual_mod_name, import_all, loc)],
225 imp_dep_mods = mkModDeps dependent_mods,
226 imp_dep_pkgs = dependent_pkgs
229 -- Complain if we import a deprecated module
230 ifDOptM Opt_WarnWarningsDeprecations (
232 WarnAll txt -> addWarn (moduleWarn imp_mod_name txt)
236 let new_imp_decl = L loc (ImportDecl loc_imp_mod_name mb_pkg want_boot
237 qual_only as_mod new_imp_details)
239 return (new_imp_decl, gbl_env, imports, mi_hpc iface)
242 warnRedundantSourceImport :: ModuleName -> SDoc
243 warnRedundantSourceImport mod_name
244 = ptext (sLit "Unnecessary {-# SOURCE #-} in the import of module")
245 <+> quotes (ppr mod_name)
249 %************************************************************************
251 \subsection{importsFromLocalDecls}
253 %************************************************************************
255 From the top-level declarations of this module produce
256 * the lexical environment
258 created by its bindings.
260 Note [Top-level Names in Template Haskell decl quotes]
261 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
262 Consider a Template Haskell declaration quotation like this:
265 When renaming the declarations inside [d| ...|], we treat the
266 top level binders specially in two ways
268 1. We give them an Internal name, not (as usual) an External one.
269 Otherwise the NameCache gets confused by a second allocation of
270 M.f. (We used to invent a fake module ThFake to avoid this, but
271 that had other problems, notably in getting the correct answer for
272 nameIsLocalOrFrom in lookupFixity. So we now leave tcg_module
275 2. We make them *shadow* the outer bindings. If we don't do that,
276 we'll get a complaint when extending the GlobalRdrEnv, saying that
277 there are two bindings for 'f'. There are several tricky points:
279 * This shadowing applies even if the binding for 'f' is in a
280 where-clause, and hence is in the *local* RdrEnv not the *global*
283 * The *qualified* name M.f from the enclosing module must certainly
284 still be available. So we don't nuke it entirely; we just make
285 it seem like qualified import.
287 * We only shadow *External* names (which come from the main module)
288 Do not shadow *Inernal* names because in the bracket
289 [d| class C a where f :: a
291 rnSrcDecls will first call extendGlobalRdrEnvRn with C[f] from the
292 class decl, and *separately* extend the envt with the value binding.
294 3. We find out whether we are inside a [d| ... |] by testing the TH
295 stage. This is a slight hack, because the stage field was really
296 meant for the type checker, and here we are not interested in the
297 fields of Brack, hence the error thunks in thRnBrack.
300 extendGlobalRdrEnvRn :: [AvailInfo]
302 -> RnM (TcGblEnv, TcLclEnv)
303 -- Updates both the GlobalRdrEnv and the FixityEnv
304 -- We return a new TcLclEnv only because we might have to
305 -- delete some bindings from it;
306 -- see Note [Top-level Names in Template Haskell decl quotes]
308 extendGlobalRdrEnvRn avails new_fixities
309 = do { (gbl_env, lcl_env) <- getEnvs
311 ; let rdr_env = tcg_rdr_env gbl_env
312 fix_env = tcg_fix_env gbl_env
314 -- Delete new_occs from global and local envs
315 -- If we are in a TemplateHaskell decl bracket,
316 -- we are going to shadow them
317 -- See Note [Top-level Names in Template Haskell decl quotes]
318 shadowP = isBrackStage stage
319 new_occs = map (nameOccName . gre_name) gres
320 rdr_env1 = transformGREs qual_gre new_occs rdr_env
321 lcl_env1 = lcl_env { tcl_rdr = delListFromOccEnv (tcl_rdr lcl_env) new_occs }
322 (rdr_env2, lcl_env2) | shadowP = (rdr_env1, lcl_env1)
323 | otherwise = (rdr_env, lcl_env)
325 rdr_env3 = foldl extendGlobalRdrEnv rdr_env2 gres
326 fix_env' = foldl extend_fix_env fix_env gres
327 (rdr_env', dups) = findLocalDupsRdrEnv rdr_env3 new_occs
329 gbl_env' = gbl_env { tcg_rdr_env = rdr_env', tcg_fix_env = fix_env' }
331 ; mapM_ addDupDeclErr dups
333 ; traceRn (text "extendGlobalRdrEnvRn" <+> (ppr new_fixities $$ ppr fix_env $$ ppr fix_env'))
334 ; return (gbl_env', lcl_env2) }
336 gres = gresFromAvails LocalDef avails
338 -- If there is a fixity decl for the gre, add it to the fixity env
339 extend_fix_env fix_env gre
340 | Just (L _ fi) <- lookupFsEnv new_fixities (occNameFS occ)
341 = extendNameEnv fix_env name (FixItem occ fi)
346 occ = nameOccName name
348 qual_gre :: GlobalRdrElt -> GlobalRdrElt
349 -- Transform top-level GREs from the module being compiled
350 -- so that they are out of the way of new definitions in a Template
352 -- See Note [Top-level Names in Template Haskell decl quotes]
353 -- Seems like 5 times as much work as it deserves!
355 -- For a LocalDef we make a (fake) qualified imported GRE for a
356 -- local GRE so that the original *qualified* name is still in scope
357 -- but the *unqualified* one no longer is. What a hack!
359 qual_gre gre@(GRE { gre_prov = LocalDef, gre_name = name })
360 | isExternalName name = gre { gre_prov = Imported [imp_spec] }
362 -- Do not shadow Internal (ie Template Haskell) Names
363 -- See Note [Top-level Names in Template Haskell decl quotes]
365 mod = ASSERT2( isExternalName name, ppr name) moduleName (nameModule name)
366 imp_spec = ImpSpec { is_item = ImpAll, is_decl = decl_spec }
367 decl_spec = ImpDeclSpec { is_mod = mod, is_as = mod,
368 is_qual = True, -- Qualified only!
369 is_dloc = srcLocSpan (nameSrcLoc name) }
371 qual_gre gre@(GRE { gre_prov = Imported specs })
372 = gre { gre_prov = Imported (map qual_spec specs) }
374 qual_spec spec@(ImpSpec { is_decl = decl_spec })
375 = spec { is_decl = decl_spec { is_qual = True } }
378 @getLocalDeclBinders@ returns the names for an @HsDecl@. It's
379 used for source code.
381 *** See "THE NAMING STORY" in HsDecls ****
383 Instances of type families
384 ~~~~~~~~~~~~~~~~~~~~~~~~~~
385 Family instances contain data constructors that we need to collect and we also
386 need to descend into the type instances of associated families in class
387 instances. The type constructor of a family instance is a usage occurence.
388 Hence, we don't return it as a subname in 'AvailInfo'; otherwise, we would get
389 a duplicate declaration error.
391 Note [Looking up family names in family instances]
392 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
397 type instance M.T Int = Bool
399 We might think that we can simply use 'lookupOccRn' when processing the type
400 instance to look up 'M.T'. Alas, we can't! The type family declaration is in
401 the *same* HsGroup as the type instance declaration. Hence, as we are
402 currently collecting the binders declared in that HsGroup, these binders will
403 not have been added to the global environment yet.
405 In the case of type classes, this problem does not arise, as a class instance
406 does not define any binders of it's own. So, we simply don't attempt to look
407 up the class names of class instances in 'get_local_binders' below.
409 If we don't look up class instances, can't we get away without looking up type
410 instances, too? No, we can't. Data type instances define data constructors
413 (1) collect those in 'get_local_binders' and
414 (2) we need to get their parent name in 'get_local_binders', too, to
415 produce an appropriate 'AvailTC'.
417 This parent name is exactly the family name of the type instance that is so
418 difficult to look up.
420 We solve this problem as follows:
422 (a) We process all type declarations other than type instances first.
423 (b) Then, we compute a 'GlobalRdrEnv' from the result of the first step.
424 (c) Finally, we process all type instances (both those on the toplevel and
425 those nested in class instances) and check for the family names in the
426 'GlobalRdrEnv' produced in the previous step before using 'lookupOccRn'.
429 getLocalNonValBinders :: HsGroup RdrName -> RnM [AvailInfo]
430 -- Get all the top-level binders bound the group *except*
431 -- for value bindings, which are treated separately
432 -- Specificaly we return AvailInfo for
433 -- type decls (incl constructors and record selectors)
434 -- class decls (including class ops)
437 -- (in hs-boot files) value signatures
439 getLocalNonValBinders group
440 = do { gbl_env <- getGblEnv
441 ; get_local_binders gbl_env group }
443 get_local_binders :: TcGblEnv -> HsGroup RdrName -> RnM [GenAvailInfo Name]
444 get_local_binders gbl_env (HsGroup {hs_valds = ValBindsIn _ val_sigs,
445 hs_tyclds = tycl_decls,
446 hs_instds = inst_decls,
447 hs_fords = foreign_decls })
448 = do { -- separate out the family instance declarations
449 let (tyinst_decls1, tycl_decls_noinsts)
450 = partition (isFamInstDecl . unLoc) (concat tycl_decls)
451 tyinst_decls = tyinst_decls1 ++ instDeclATs inst_decls
453 -- process all type/class decls except family instances
454 ; tc_names <- mapM new_tc tycl_decls_noinsts
456 -- create a temporary rdr env of the type binders
457 ; let tc_gres = gresFromAvails LocalDef tc_names
458 tc_name_env = foldl extendGlobalRdrEnv emptyGlobalRdrEnv tc_gres
460 -- process all family instances
461 ; ti_names <- mapM (new_ti tc_name_env) tyinst_decls
463 -- finish off with value binder in case of a hs-boot file
464 ; val_names <- mapM new_simple val_bndrs
465 ; return (val_names ++ tc_names ++ ti_names) }
467 is_hs_boot = isHsBoot (tcg_src gbl_env) ;
469 for_hs_bndrs :: [Located RdrName]
470 for_hs_bndrs = [nm | L _ (ForeignImport nm _ _) <- foreign_decls]
472 -- In a hs-boot file, the value binders come from the
473 -- *signatures*, and there should be no foreign binders
474 val_bndrs :: [Located RdrName]
475 val_bndrs | is_hs_boot = [nm | L _ (TypeSig nm _) <- val_sigs]
476 | otherwise = for_hs_bndrs
478 new_simple :: Located RdrName -> RnM (GenAvailInfo Name)
479 new_simple rdr_name = do
480 nm <- newTopSrcBinder rdr_name
483 new_tc tc_decl -- NOT for type/data instances
484 = do { main_name <- newTopSrcBinder main_rdr
485 ; sub_names <- mapM newTopSrcBinder sub_rdrs
486 ; return (AvailTC main_name (main_name : sub_names)) }
488 (main_rdr : sub_rdrs) = hsTyClDeclBinders tc_decl
490 new_ti tc_name_env ti_decl -- ONLY for type/data instances
491 = do { main_name <- lookupFamInstDeclBndr tc_name_env main_rdr
492 ; sub_names <- mapM newTopSrcBinder sub_rdrs
493 ; return (AvailTC main_name sub_names) }
494 -- main_name is not bound here!
496 (main_rdr : sub_rdrs) = hsTyClDeclBinders ti_decl
498 get_local_binders _ g = pprPanic "get_local_binders" (ppr g)
502 %************************************************************************
504 \subsection{Filtering imports}
506 %************************************************************************
508 @filterImports@ takes the @ExportEnv@ telling what the imported module makes
509 available, and filters it through the import spec (if any).
512 filterImports :: ModIface
513 -> ImpDeclSpec -- The span for the entire import decl
514 -> Maybe (Bool, [LIE RdrName]) -- Import spec; True => hiding
515 -> [AvailInfo] -- What's available
516 -> RnM (Maybe (Bool, [LIE Name]), -- Import spec w/ Names
517 GlobalRdrEnv) -- Same again, but in GRE form
518 filterImports _ decl_spec Nothing all_avails
519 = return (Nothing, mkGlobalRdrEnv (gresFromAvails prov all_avails))
521 prov = Imported [ImpSpec { is_decl = decl_spec, is_item = ImpAll }]
524 filterImports iface decl_spec (Just (want_hiding, import_items)) all_avails
525 = do -- check for errors, convert RdrNames to Names
526 opt_typeFamilies <- xoptM Opt_TypeFamilies
527 items1 <- mapM (lookup_lie opt_typeFamilies) import_items
529 let items2 :: [(LIE Name, AvailInfo)]
530 items2 = concat items1
531 -- NB the AvailInfo may have duplicates, and several items
532 -- for the same parent; e.g N(x) and N(y)
534 names = availsToNameSet (map snd items2)
535 keep n = not (n `elemNameSet` names)
536 pruned_avails = filterAvails keep all_avails
537 hiding_prov = Imported [ImpSpec { is_decl = decl_spec, is_item = ImpAll }]
539 gres | want_hiding = gresFromAvails hiding_prov pruned_avails
540 | otherwise = concatMap (gresFromIE decl_spec) items2
542 return (Just (want_hiding, map fst items2), mkGlobalRdrEnv gres)
544 -- This environment is how we map names mentioned in the import
545 -- list to the actual Name they correspond to, and the name family
546 -- that the Name belongs to (the AvailInfo). The situation is
547 -- complicated by associated families, which introduce a three-level
548 -- hierachy, where class = grand parent, assoc family = parent, and
549 -- data constructors = children. The occ_env entries for associated
550 -- families needs to capture all this information; hence, we have the
551 -- third component of the environment that gives the class name (=
552 -- grand parent) in case of associated families.
554 -- This env will have entries for data constructors too,
555 -- they won't make any difference because naked entities like T
556 -- in an import list map to TcOccs, not VarOccs.
557 occ_env :: OccEnv (Name, -- the name
558 AvailInfo, -- the export item providing the name
559 Maybe Name) -- the parent of associated types
560 occ_env = mkOccEnv_C combine [ (nameOccName n, (n, a, Nothing))
561 | a <- all_avails, n <- availNames a]
563 -- we know that (1) there are at most entries for one name, (2) their
564 -- first component is identical, (3) they are for tys/cls, and (4) one
565 -- entry has the name in its parent position (the other doesn't)
566 combine (name, AvailTC p1 subs1, Nothing)
567 (_ , AvailTC p2 subs2, Nothing)
569 (parent, subs) = if p1 == name then (p2, subs1) else (p1, subs2)
571 (name, AvailTC name subs, Just parent)
572 combine x y = pprPanic "filterImports/combine" (ppr x $$ ppr y)
574 lookup_lie :: Bool -> LIE RdrName -> TcRn [(LIE Name, AvailInfo)]
575 lookup_lie opt_typeFamilies (L loc ieRdr)
577 stuff <- setSrcSpan loc $
578 case lookup_ie opt_typeFamilies ieRdr of
579 Failed err -> addErr err >> return []
580 Succeeded a -> return a
581 checkDodgyImport stuff
582 return [ (L loc ie, avail) | (ie,avail) <- stuff ]
584 -- Warn when importing T(..) if T was exported abstractly
585 checkDodgyImport stuff
586 | IEThingAll n <- ieRdr, (_, AvailTC _ [_]):_ <- stuff
587 = ifDOptM Opt_WarnDodgyImports (addWarn (dodgyImportWarn n))
588 -- NB. use the RdrName for reporting the warning
589 | IEThingAll {} <- ieRdr
590 , not (is_qual decl_spec)
591 = ifDOptM Opt_WarnMissingImportList $
592 addWarn (missingImportListItem ieRdr)
596 -- For each import item, we convert its RdrNames to Names,
597 -- and at the same time construct an AvailInfo corresponding
598 -- to what is actually imported by this item.
599 -- Returns Nothing on error.
600 -- We return a list here, because in the case of an import
601 -- item like C, if we are hiding, then C refers to *both* a
602 -- type/class and a data constructor. Moreover, when we import
603 -- data constructors of an associated family, we need separate
604 -- AvailInfos for the data constructors and the family (as they have
605 -- different parents). See the discussion at occ_env.
606 lookup_ie :: Bool -> IE RdrName -> MaybeErr Message [(IE Name,AvailInfo)]
607 lookup_ie opt_typeFamilies ie
608 = let bad_ie :: MaybeErr Message a
609 bad_ie = Failed (badImportItemErr iface decl_spec ie all_avails)
612 | isQual rdr = Failed (qualImportItemErr rdr)
613 | Just nm <- lookupOccEnv occ_env (rdrNameOcc rdr) = return nm
618 (name, avail, _) <- lookup_name n
619 return [(IEVar name, trimAvail avail name)]
622 (name, avail@(AvailTC name2 subs), mb_parent) <- lookup_name tc
624 -- non-associated ty/cls
625 Nothing -> return [(IEThingAll name, avail)]
627 Just parent -> return [(IEThingAll name,
628 AvailTC name2 (subs \\ [name])),
629 (IEThingAll name, AvailTC parent [name])]
632 | want_hiding -- hiding ( C )
633 -- Here the 'C' can be a data constructor
634 -- *or* a type/class, or even both
635 -> let tc_name = lookup_name tc
636 dc_name = lookup_name (setRdrNameSpace tc srcDataName)
638 case catMaybeErr [ tc_name, dc_name ] of
640 names -> return [mkIEThingAbs name | name <- names]
642 -> do nameAvail <- lookup_name tc
643 return [mkIEThingAbs nameAvail]
645 IEThingWith tc ns -> do
646 (name, AvailTC _ subnames, mb_parent) <- lookup_name tc
648 env = mkOccEnv [(nameOccName s, s) | s <- subnames]
649 mb_children = map (lookupOccEnv env . rdrNameOcc) ns
650 children <- if any isNothing mb_children
652 else return (catMaybes mb_children)
653 -- check for proper import of type families
654 when (not opt_typeFamilies && any isTyConName children) $
655 Failed (typeItemErr (head . filter isTyConName $ children)
656 (text "in import list"))
658 -- non-associated ty/cls
659 Nothing -> return [(IEThingWith name children,
660 AvailTC name (name:children))]
662 Just parent -> return [(IEThingWith name children,
663 AvailTC name children),
664 (IEThingWith name children,
665 AvailTC parent [name])]
667 _other -> Failed illegalImportItemErr
668 -- could be IEModuleContents, IEGroup, IEDoc, IEDocNamed
672 mkIEThingAbs (n, av, Nothing ) = (IEThingAbs n, trimAvail av n)
673 mkIEThingAbs (n, _, Just parent) = (IEThingAbs n, AvailTC parent [n])
676 catMaybeErr :: [MaybeErr err a] -> [a]
677 catMaybeErr ms = [ a | Succeeded a <- ms ]
680 %************************************************************************
682 \subsection{Import/Export Utils}
684 %************************************************************************
687 -- | make a 'GlobalRdrEnv' where all the elements point to the same
688 -- import declaration (useful for "hiding" imports, or imports with
690 gresFromAvails :: Provenance -> [AvailInfo] -> [GlobalRdrElt]
691 gresFromAvails prov avails
692 = concatMap (gresFromAvail (const prov)) avails
694 gresFromAvail :: (Name -> Provenance) -> AvailInfo -> [GlobalRdrElt]
695 gresFromAvail prov_fn avail
696 = [ GRE {gre_name = n,
697 gre_par = availParent n avail,
698 gre_prov = prov_fn n}
699 | n <- availNames avail ]
701 greAvail :: GlobalRdrElt -> AvailInfo
702 greAvail gre = mkUnitAvail (gre_name gre) (gre_par gre)
704 mkUnitAvail :: Name -> Parent -> AvailInfo
705 mkUnitAvail me (ParentIs p) = AvailTC p [me]
706 mkUnitAvail me NoParent | isTyConName me = AvailTC me [me]
707 | otherwise = Avail me
709 plusAvail :: GenAvailInfo Name -> GenAvailInfo Name -> GenAvailInfo Name
710 plusAvail (Avail n1) (Avail _) = Avail n1
711 plusAvail (AvailTC _ ns1) (AvailTC n2 ns2) = AvailTC n2 (ns1 `unionLists` ns2)
712 plusAvail a1 a2 = pprPanic "RnEnv.plusAvail" (hsep [ppr a1,ppr a2])
714 availParent :: Name -> AvailInfo -> Parent
715 availParent _ (Avail _) = NoParent
716 availParent n (AvailTC m _) | n == m = NoParent
717 | otherwise = ParentIs m
719 trimAvail :: AvailInfo -> Name -> AvailInfo
720 trimAvail (Avail n) _ = Avail n
721 trimAvail (AvailTC n ns) m = ASSERT( m `elem` ns) AvailTC n [m]
723 -- | filters 'AvailInfo's by the given predicate
724 filterAvails :: (Name -> Bool) -> [AvailInfo] -> [AvailInfo]
725 filterAvails keep avails = foldr (filterAvail keep) [] avails
727 -- | filters an 'AvailInfo' by the given predicate
728 filterAvail :: (Name -> Bool) -> AvailInfo -> [AvailInfo] -> [AvailInfo]
729 filterAvail keep ie rest =
731 Avail n | keep n -> ie : rest
734 let left = filter keep ns in
735 if null left then rest else AvailTC tc left : rest
737 -- | Given an import\/export spec, construct the appropriate 'GlobalRdrElt's.
738 gresFromIE :: ImpDeclSpec -> (LIE Name, AvailInfo) -> [GlobalRdrElt]
739 gresFromIE decl_spec (L loc ie, avail)
740 = gresFromAvail prov_fn avail
742 is_explicit = case ie of
743 IEThingAll name -> \n -> n == name
745 prov_fn name = Imported [imp_spec]
747 imp_spec = ImpSpec { is_decl = decl_spec, is_item = item_spec }
748 item_spec = ImpSome { is_explicit = is_explicit name, is_iloc = loc }
750 mkChildEnv :: [GlobalRdrElt] -> NameEnv [Name]
751 mkChildEnv gres = foldr add emptyNameEnv gres
753 add (GRE { gre_name = n, gre_par = ParentIs p }) env = extendNameEnv_Acc (:) singleton env p n
756 findChildren :: NameEnv [Name] -> Name -> [Name]
757 findChildren env n = lookupNameEnv env n `orElse` []
760 ---------------------------------------
763 All this AvailEnv stuff is hardly used; only in a very small
764 part of RnNames. Todo: remove?
765 ---------------------------------------
768 type AvailEnv = NameEnv AvailInfo -- Maps a Name to the AvailInfo that contains it
770 emptyAvailEnv :: AvailEnv
771 emptyAvailEnv = emptyNameEnv
774 unitAvailEnv :: AvailInfo -> AvailEnv
775 unitAvailEnv a = unitNameEnv (availName a) a
777 plusAvailEnv :: AvailEnv -> AvailEnv -> AvailEnv
778 plusAvailEnv = plusNameEnv_C plusAvail
780 availEnvElts :: AvailEnv -> [AvailInfo]
781 availEnvElts = nameEnvElts
784 addAvail :: AvailEnv -> AvailInfo -> AvailEnv
785 addAvail avails avail = extendNameEnv_C plusAvail avails (availName avail) avail
787 mkAvailEnv :: [AvailInfo] -> AvailEnv
788 -- 'avails' may have several items with the same availName
789 -- E.g import Ix( Ix(..), index )
790 -- will give Ix(Ix,index,range) and Ix(index)
791 -- We want to combine these; addAvail does that
792 mkAvailEnv avails = foldl addAvail emptyAvailEnv avails
794 -- After combining the avails, we need to ensure that the parent name is the
795 -- first entry in the list of subnames, if it is included at all. (Subsequent
796 -- functions rely on that.)
797 normaliseAvail :: AvailInfo -> AvailInfo
798 normaliseAvail avail@(Avail _) = avail
799 normaliseAvail (AvailTC name subs) = AvailTC name subs'
801 subs' = if name `elem` subs then name : (delete name subs) else subs
803 -- | combines 'AvailInfo's from the same family
804 nubAvails :: [AvailInfo] -> [AvailInfo]
805 nubAvails avails = map normaliseAvail . nameEnvElts . mkAvailEnv $ avails
809 %************************************************************************
811 \subsection{Export list processing}
813 %************************************************************************
815 Processing the export list.
817 You might think that we should record things that appear in the export
818 list as ``occurrences'' (using @addOccurrenceName@), but you'd be
819 wrong. We do check (here) that they are in scope, but there is no
820 need to slurp in their actual declaration (which is what
821 @addOccurrenceName@ forces).
823 Indeed, doing so would big trouble when compiling @PrelBase@, because
824 it re-exports @GHC@, which includes @takeMVar#@, whose type includes
825 @ConcBase.StateAndSynchVar#@, and so on...
828 type ExportAccum -- The type of the accumulating parameter of
829 -- the main worker function in rnExports
830 = ([LIE Name], -- Export items with Names
831 ExportOccMap, -- Tracks exported occurrence names
832 [AvailInfo]) -- The accumulated exported stuff
835 emptyExportAccum :: ExportAccum
836 emptyExportAccum = ([], emptyOccEnv, [])
838 type ExportOccMap = OccEnv (Name, IE RdrName)
839 -- Tracks what a particular exported OccName
840 -- in an export list refers to, and which item
841 -- it came from. It's illegal to export two distinct things
842 -- that have the same occurrence name
844 rnExports :: Bool -- False => no 'module M(..) where' header at all
845 -> Maybe [LIE RdrName] -- Nothing => no explicit export list
849 -- Complains if two distinct exports have same OccName
850 -- Warns about identical exports.
851 -- Complains about exports items not in scope
853 rnExports explicit_mod exports
854 tcg_env@(TcGblEnv { tcg_mod = this_mod,
855 tcg_rdr_env = rdr_env,
856 tcg_imports = imports })
858 -- If the module header is omitted altogether, then behave
859 -- as if the user had written "module Main(main) where..."
860 -- EXCEPT in interactive mode, when we behave as if he had
861 -- written "module Main where ..."
862 -- Reason: don't want to complain about 'main' not in scope
863 -- in interactive mode
866 | explicit_mod = exports
867 | ghcLink dflags == LinkInMemory = Nothing
868 | otherwise = Just ([noLoc (IEVar main_RDR_Unqual)])
869 -- ToDo: the 'noLoc' here is unhelpful if 'main'
870 -- turns out to be out of scope
872 ; (rn_exports, avails) <- exports_from_avail real_exports rdr_env imports this_mod
873 ; let final_avails = nubAvails avails -- Combine families
875 ; return (tcg_env { tcg_exports = final_avails,
876 tcg_rn_exports = case tcg_rn_exports tcg_env of
878 Just _ -> rn_exports,
879 tcg_dus = tcg_dus tcg_env `plusDU`
880 usesOnly (availsToNameSet final_avails) }) }
882 exports_from_avail :: Maybe [LIE RdrName]
883 -- Nothing => no explicit export list
887 -> RnM (Maybe [LIE Name], [AvailInfo])
889 exports_from_avail Nothing rdr_env _imports _this_mod
890 = -- The same as (module M) where M is the current module name,
891 -- so that's how we handle it.
893 avails = [ greAvail gre | gre <- globalRdrEnvElts rdr_env,
896 return (Nothing, avails)
898 exports_from_avail (Just rdr_items) rdr_env imports this_mod
899 = do (ie_names, _, exports) <- foldlM do_litem emptyExportAccum rdr_items
901 return (Just ie_names, exports)
903 do_litem :: ExportAccum -> LIE RdrName -> RnM ExportAccum
904 do_litem acc lie = setSrcSpan (getLoc lie) (exports_from_item acc lie)
906 kids_env :: NameEnv [Name] -- Maps a parent to its in-scope children
907 kids_env = mkChildEnv (globalRdrEnvElts rdr_env)
909 imported_modules = [ qual_name
910 | xs <- moduleEnvElts $ imp_mods imports,
911 (qual_name, _, _) <- xs ]
913 exports_from_item :: ExportAccum -> LIE RdrName -> RnM ExportAccum
914 exports_from_item acc@(ie_names, occs, exports)
915 (L loc ie@(IEModuleContents mod))
916 | let earlier_mods = [ mod | (L _ (IEModuleContents mod)) <- ie_names ]
917 , mod `elem` earlier_mods -- Duplicate export of M
918 = do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
919 warnIf warn_dup_exports (dupModuleExport mod) ;
923 = do { implicit_prelude <- xoptM Opt_ImplicitPrelude
924 ; warnDodgyExports <- doptM Opt_WarnDodgyExports
925 ; let { exportValid = (mod `elem` imported_modules)
926 || (moduleName this_mod == mod)
927 ; gres = filter (isModuleExported implicit_prelude mod)
928 (globalRdrEnvElts rdr_env)
929 ; names = map gre_name gres
932 ; checkErr exportValid (moduleNotImported mod)
933 ; warnIf (warnDodgyExports && exportValid && null gres) (nullModuleExport mod)
935 ; addUsedRdrNames (concat [ [mkRdrQual mod occ, mkRdrUnqual occ]
936 | occ <- map nameOccName names ])
937 -- The qualified and unqualified version of all of
938 -- these names are, in effect, used by this export
940 ; occs' <- check_occs ie occs names
941 -- This check_occs not only finds conflicts
942 -- between this item and others, but also
943 -- internally within this item. That is, if
944 -- 'M.x' is in scope in several ways, we'll have
945 -- several members of mod_avails with the same
947 ; return (L loc (IEModuleContents mod) : ie_names,
948 occs', map greAvail gres ++ exports) }
950 exports_from_item acc@(lie_names, occs, exports) (L loc ie)
952 = do new_ie <- lookup_doc_ie ie
953 return (L loc new_ie : lie_names, occs, exports)
956 = do (new_ie, avail) <- lookup_ie ie
957 if isUnboundName (ieName new_ie)
958 then return acc -- Avoid error cascade
961 occs' <- check_occs ie occs (availNames avail)
963 return (L loc new_ie : lie_names, occs', avail : exports)
966 lookup_ie :: IE RdrName -> RnM (IE Name, AvailInfo)
967 lookup_ie (IEVar rdr)
968 = do gre <- lookupGreRn rdr
969 return (IEVar (gre_name gre), greAvail gre)
971 lookup_ie (IEThingAbs rdr)
972 = do gre <- lookupGreRn rdr
973 let name = gre_name gre
975 NoParent -> return (IEThingAbs name,
977 ParentIs p -> return (IEThingAbs name,
980 lookup_ie ie@(IEThingAll rdr)
981 = do name <- lookupGlobalOccRn rdr
982 let kids = findChildren kids_env name
983 mkKidRdrName = case isQual_maybe rdr of
984 Nothing -> mkRdrUnqual
985 Just (modName, _) -> mkRdrQual modName
986 addUsedRdrNames $ map (mkKidRdrName . nameOccName) kids
987 warnDodgyExports <- doptM Opt_WarnDodgyExports
990 then when warnDodgyExports $ addWarn (dodgyExportWarn name)
991 else -- This occurs when you export T(..), but
992 -- only import T abstractly, or T is a synonym.
993 addErr (exportItemErr ie)
995 return (IEThingAll name, AvailTC name (name:kids))
997 lookup_ie ie@(IEThingWith rdr sub_rdrs)
998 = do name <- lookupGlobalOccRn rdr
999 if isUnboundName name
1000 then return (IEThingWith name [], AvailTC name [name])
1002 let env = mkOccEnv [ (nameOccName s, s)
1003 | s <- findChildren kids_env name ]
1004 mb_names = map (lookupOccEnv env . rdrNameOcc) sub_rdrs
1005 if any isNothing mb_names
1006 then do addErr (exportItemErr ie)
1007 return (IEThingWith name [], AvailTC name [name])
1008 else do let names = catMaybes mb_names
1009 optTyFam <- xoptM Opt_TypeFamilies
1010 when (not optTyFam && any isTyConName names) $
1011 addErr (typeItemErr ( head
1012 . filter isTyConName
1014 (text "in export list"))
1015 return (IEThingWith name names, AvailTC name (name:names))
1017 lookup_ie _ = panic "lookup_ie" -- Other cases covered earlier
1020 lookup_doc_ie :: IE RdrName -> RnM (IE Name)
1021 lookup_doc_ie (IEGroup lev doc) = do rn_doc <- rnHsDoc doc
1022 return (IEGroup lev rn_doc)
1023 lookup_doc_ie (IEDoc doc) = do rn_doc <- rnHsDoc doc
1024 return (IEDoc rn_doc)
1025 lookup_doc_ie (IEDocNamed str) = return (IEDocNamed str)
1026 lookup_doc_ie _ = panic "lookup_doc_ie" -- Other cases covered earlier
1029 isDoc :: IE RdrName -> Bool
1030 isDoc (IEDoc _) = True
1031 isDoc (IEDocNamed _) = True
1032 isDoc (IEGroup _ _) = True
1035 -------------------------------
1036 isModuleExported :: Bool -> ModuleName -> GlobalRdrElt -> Bool
1037 -- True if the thing is in scope *both* unqualified, *and* with qualifier M
1038 isModuleExported implicit_prelude mod (GRE { gre_name = name, gre_prov = prov })
1039 | implicit_prelude && isBuiltInSyntax name = False
1040 -- Optimisation: filter out names for built-in syntax
1041 -- They just clutter up the environment (esp tuples), and the parser
1042 -- will generate Exact RdrNames for them, so the cluttered
1043 -- envt is no use. To avoid doing this filter all the time,
1044 -- we use -XNoImplicitPrelude as a clue that the filter is
1045 -- worth while. Really, it's only useful for GHC.Base and GHC.Tuple.
1047 -- It's worth doing because it makes the environment smaller for
1048 -- every module that imports the Prelude
1051 LocalDef | Just name_mod <- nameModule_maybe name
1052 -> moduleName name_mod == mod
1053 | otherwise -> False
1054 Imported is -> any unQualSpecOK is && any (qualSpecOK mod) is
1056 -------------------------------
1057 check_occs :: IE RdrName -> ExportOccMap -> [Name] -> RnM ExportOccMap
1058 check_occs ie occs names
1059 = foldlM check occs names
1062 = case lookupOccEnv occs name_occ of
1063 Nothing -> return (extendOccEnv occs name_occ (name, ie))
1066 | name == name' -- Duplicate export
1067 -- But we don't want to warn if the same thing is exported
1068 -- by two different module exports. See ticket #4478.
1069 -> do unless (diffModules ie ie') $ do
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 badImportItemErrStd :: ModIface -> ImpDeclSpec -> IE RdrName -> SDoc
1462 badImportItemErrStd 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 badImportItemErrDataCon :: OccName -> ModIface -> ImpDeclSpec -> IE RdrName -> SDoc
1470 badImportItemErrDataCon dataType iface decl_spec ie
1471 = vcat [ ptext (sLit "In module")
1472 <+> quotes (ppr (is_mod decl_spec))
1473 <+> source_import <> colon
1474 , nest 2 $ quotes datacon
1475 <+> ptext (sLit "is a data constructor of")
1476 <+> quotes (ppr dataType)
1477 , ptext (sLit "To import it use")
1478 , nest 2 $ quotes (ptext (sLit "import")
1479 <+> ppr (is_mod decl_spec)
1480 <+> parens (ppr dataType <+> parens datacon))
1482 , nest 2 $ quotes (ptext (sLit "import")
1483 <+> ppr (is_mod decl_spec)
1484 <+> parens (ppr dataType <+> parens (ptext $ sLit "..")))
1487 datacon = ppr . rdrNameOcc $ ieName ie
1488 source_import | mi_boot iface = ptext (sLit "(hi-boot interface)")
1491 badImportItemErr :: ModIface -> ImpDeclSpec -> IE RdrName -> [AvailInfo] -> SDoc
1492 badImportItemErr iface decl_spec ie avails
1493 = case find checkIfDataCon avails of
1494 Just con -> badImportItemErrDataCon (availOccName con) iface decl_spec ie
1495 Nothing -> badImportItemErrStd iface decl_spec ie
1497 checkIfDataCon (AvailTC _ ns) =
1498 case find (\n -> importedFS == nameOccNameFS n) ns of
1499 Just n -> isDataConName n
1501 checkIfDataCon _ = False
1502 availOccName = nameOccName . availName
1503 nameOccNameFS = occNameFS . nameOccName
1504 importedFS = occNameFS . rdrNameOcc $ ieName ie
1506 illegalImportItemErr :: SDoc
1507 illegalImportItemErr = ptext (sLit "Illegal import item")
1509 dodgyImportWarn :: RdrName -> SDoc
1510 dodgyImportWarn item = dodgyMsg (ptext (sLit "import")) item
1511 dodgyExportWarn :: Name -> SDoc
1512 dodgyExportWarn item = dodgyMsg (ptext (sLit "export")) item
1514 dodgyMsg :: OutputableBndr n => SDoc -> n -> SDoc
1516 = sep [ ptext (sLit "The") <+> kind <+> ptext (sLit "item") <+> quotes (ppr (IEThingAll tc))
1517 <+> ptext (sLit "suggests that"),
1518 quotes (ppr tc) <+> ptext (sLit "has (in-scope) constructors or class methods,"),
1519 ptext (sLit "but it has none") ]
1521 exportItemErr :: IE RdrName -> SDoc
1522 exportItemErr export_item
1523 = sep [ ptext (sLit "The export item") <+> quotes (ppr export_item),
1524 ptext (sLit "attempts to export constructors or class methods that are not visible here") ]
1526 typeItemErr :: Name -> SDoc -> SDoc
1527 typeItemErr name wherestr
1528 = sep [ ptext (sLit "Using 'type' tag on") <+> quotes (ppr name) <+> wherestr,
1529 ptext (sLit "Use -XTypeFamilies to enable this extension") ]
1531 exportClashErr :: GlobalRdrEnv -> Name -> Name -> IE RdrName -> IE RdrName
1533 exportClashErr global_env name1 name2 ie1 ie2
1534 = vcat [ ptext (sLit "Conflicting exports for") <+> quotes (ppr occ) <> colon
1535 , ppr_export ie1' name1'
1536 , ppr_export ie2' name2' ]
1538 occ = nameOccName name1
1539 ppr_export ie name = nest 2 (quotes (ppr ie) <+> ptext (sLit "exports") <+>
1540 quotes (ppr name) <+> pprNameProvenance (get_gre name))
1542 -- get_gre finds a GRE for the Name, so that we can show its provenance
1544 = case lookupGRE_Name global_env name of
1546 [] -> pprPanic "exportClashErr" (ppr name)
1547 get_loc name = greSrcSpan (get_gre name)
1548 (name1', ie1', name2', ie2') = if get_loc name1 < get_loc name2
1549 then (name1, ie1, name2, ie2)
1550 else (name2, ie2, name1, ie1)
1552 -- the SrcSpan that pprNameProvenance prints out depends on whether
1553 -- the Name is defined locally or not: for a local definition the
1554 -- definition site is used, otherwise the location of the import
1555 -- declaration. We want to sort the export locations in
1556 -- exportClashErr by this SrcSpan, we need to extract it:
1557 greSrcSpan :: GlobalRdrElt -> SrcSpan
1559 | Imported (is:_) <- gre_prov gre = is_dloc (is_decl is)
1560 | otherwise = name_span
1562 name_span = nameSrcSpan (gre_name gre)
1564 addDupDeclErr :: [Name] -> TcRn ()
1566 = panic "addDupDeclErr: empty list"
1567 addDupDeclErr names@(name : _)
1568 = addErrAt (getSrcSpan (last sorted_names)) $
1569 -- Report the error at the later location
1570 vcat [ptext (sLit "Multiple declarations of") <+> quotes (ppr name),
1571 ptext (sLit "Declared at:") <+> vcat (map (ppr . nameSrcLoc) sorted_names)]
1573 sorted_names = sortWith nameSrcLoc names
1575 dupExportWarn :: OccName -> IE RdrName -> IE RdrName -> SDoc
1576 dupExportWarn occ_name ie1 ie2
1577 = hsep [quotes (ppr occ_name),
1578 ptext (sLit "is exported by"), quotes (ppr ie1),
1579 ptext (sLit "and"), quotes (ppr ie2)]
1581 dupModuleExport :: ModuleName -> SDoc
1583 = hsep [ptext (sLit "Duplicate"),
1584 quotes (ptext (sLit "Module") <+> ppr mod),
1585 ptext (sLit "in export list")]
1587 moduleNotImported :: ModuleName -> SDoc
1588 moduleNotImported mod
1589 = ptext (sLit "The export item `module") <+> ppr mod <>
1590 ptext (sLit "' is not imported")
1592 nullModuleExport :: ModuleName -> SDoc
1593 nullModuleExport mod
1594 = ptext (sLit "The export item `module") <+> ppr mod <> ptext (sLit "' exports nothing")
1596 missingImportListWarn :: ModuleName -> SDoc
1597 missingImportListWarn mod
1598 = ptext (sLit "The module") <+> quotes (ppr mod) <+> ptext (sLit "does not have an explicit import list")
1600 missingImportListItem :: IE RdrName -> SDoc
1601 missingImportListItem ie
1602 = ptext (sLit "The import item") <+> quotes (ppr ie) <+> ptext (sLit "does not have an explicit import list")
1604 moduleWarn :: ModuleName -> WarningTxt -> SDoc
1605 moduleWarn mod (WarningTxt txt)
1606 = sep [ ptext (sLit "Module") <+> quotes (ppr mod) <> ptext (sLit ":"),
1607 nest 2 (vcat (map ppr txt)) ]
1608 moduleWarn mod (DeprecatedTxt txt)
1609 = sep [ ptext (sLit "Module") <+> quotes (ppr mod)
1610 <+> ptext (sLit "is deprecated:"),
1611 nest 2 (vcat (map ppr txt)) ]
1613 implicitPreludeWarn :: SDoc
1615 = ptext (sLit "Module `Prelude' implicitly imported")
1617 packageImportErr :: SDoc
1619 = ptext (sLit "Package-qualified imports are not enabled; use -XPackageImports")