2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[RnNames]{Extracting imported and top-level names in scope}
8 rnImports, mkRdrEnvAndImports, importsFromLocalDecls,
9 rnExports, mkExportNameSet,
10 getLocalDeclBinders, extendRdrEnvRn,
11 reportUnusedNames, reportDeprecations
14 #include "HsVersions.h"
16 import DynFlags ( DynFlag(..), GhcMode(..), DynFlags(..) )
17 import HsSyn ( IE(..), ieName, ImportDecl(..), LImportDecl,
18 ForeignDecl(..), HsGroup(..), HsValBinds(..),
19 Sig(..), collectHsBindLocatedBinders, tyClDeclNames,
23 import IfaceEnv ( ifaceExportNames )
24 import LoadIface ( loadSrcInterface )
25 import TcRnMonad hiding (LIE)
30 import Name ( Name, nameSrcLoc, nameOccName, nameModule, isWiredInName,
31 nameParent, nameParent_maybe, isExternalName,
35 import OccName ( srcDataName, isTcOcc, pprNonVarNameSpace,
37 OccEnv, mkOccEnv, lookupOccEnv, emptyOccEnv,
39 import HscTypes ( GenAvailInfo(..), AvailInfo,
40 HomePackageTable, PackageIfaceTable,
42 Deprecs(..), ModIface(..), Dependencies(..),
43 lookupIfaceByModule, ExternalPackageState(..)
45 import RdrName ( RdrName, rdrNameOcc, setRdrNameSpace,
46 GlobalRdrEnv, mkGlobalRdrEnv, GlobalRdrElt(..),
47 emptyGlobalRdrEnv, plusGlobalRdrEnv, globalRdrEnvElts,
48 extendGlobalRdrEnv, lookupGlobalRdrEnv, unQualOK, lookupGRE_Name,
49 Provenance(..), ImportSpec(..), ImpDeclSpec(..), ImpItemSpec(..),
50 importSpecLoc, importSpecModule, isLocalGRE, pprNameProvenance )
53 import Maybes ( isNothing, catMaybes, mapCatMaybes, seqMaybe, orElse )
54 import SrcLoc ( Located(..), mkGeneralSrcSpan,
55 unLoc, noLoc, srcLocSpan, SrcSpan )
56 import BasicTypes ( DeprecTxt )
57 import DriverPhases ( isHsBoot )
58 import Util ( notNull )
59 import List ( partition )
60 import IO ( openFile, IOMode(..) )
61 import Monad ( liftM )
66 %************************************************************************
70 %************************************************************************
73 rnImports :: [LImportDecl RdrName] -> RnM [LImportDecl Name]
75 -- PROCESS IMPORT DECLS
76 -- Do the non {- SOURCE -} ones first, so that we get a helpful
77 -- warning for {- SOURCE -} ones that are unnecessary
78 = do this_mod <- getModule
79 implicit_prelude <- doptM Opt_ImplicitPrelude
80 let all_imports = mk_prel_imports this_mod implicit_prelude ++ imports
81 (source, ordinary) = partition is_source_import all_imports
82 is_source_import (L _ (ImportDecl _ is_boot _ _ _)) = is_boot
83 get_imports = rnImportDecl this_mod
85 stuff1 <- mapM get_imports ordinary
86 stuff2 <- mapM get_imports source
87 return (stuff1 ++ stuff2)
89 -- NB: opt_NoImplicitPrelude is slightly different to import Prelude ();
90 -- because the former doesn't even look at Prelude.hi for instance
91 -- declarations, whereas the latter does.
92 mk_prel_imports this_mod implicit_prelude
94 || explicit_prelude_import
95 || not implicit_prelude
97 | otherwise = [preludeImportDecl]
98 explicit_prelude_import
99 = notNull [ () | L _ (ImportDecl mod _ _ _ _) <- imports,
100 unLoc mod == pRELUDE_NAME ]
102 preludeImportDecl :: LImportDecl RdrName
105 ImportDecl (L loc pRELUDE_NAME)
106 False {- Not a boot interface -}
107 False {- Not qualified -}
108 Nothing {- No "as" -}
109 Nothing {- No import list -}
111 loc = mkGeneralSrcSpan FSLIT("Implicit import declaration")
113 mkRdrEnvAndImports :: [LImportDecl Name] -> RnM (GlobalRdrEnv, ImportAvails)
114 mkRdrEnvAndImports imports
115 = do this_mod <- getModule
116 let get_imports = importsFromImportDecl this_mod
117 stuff <- mapM get_imports imports
118 let (imp_gbl_envs, imp_avails) = unzip stuff
119 gbl_env :: GlobalRdrEnv
120 gbl_env = foldr plusGlobalRdrEnv emptyGlobalRdrEnv imp_gbl_envs
122 all_avails :: ImportAvails
123 all_avails = foldr plusImportAvails emptyImportAvails imp_avails
125 return (gbl_env, all_avails)
130 rnImportDecl :: Module
131 -> LImportDecl RdrName
132 -> RnM (LImportDecl Name)
133 rnImportDecl this_mod (L loc importDecl@(ImportDecl loc_imp_mod_name want_boot qual_only as_mod imp_details))
135 do iface <- loadSrcInterface doc imp_mod_name want_boot
136 let qual_mod_name = case as_mod of
137 Nothing -> imp_mod_name
138 Just another_name -> another_name
139 imp_spec = ImpDeclSpec { is_mod = imp_mod_name, is_qual = qual_only,
140 is_dloc = loc, is_as = qual_mod_name }
141 total_avails <- ifaceExportNames (mi_exports iface)
142 importDecl' <- rnImportDecl' iface imp_spec importDecl total_avails
143 return (L loc importDecl')
144 where imp_mod_name = unLoc loc_imp_mod_name
145 doc = ppr imp_mod_name <+> ptext SLIT("is directly imported")
147 rnImportDecl' :: ModIface -> ImpDeclSpec -> ImportDecl RdrName -> NameSet -> RnM (ImportDecl Name)
148 rnImportDecl' iface decl_spec (ImportDecl mod_name want_boot qual_only as_mod Nothing) all_names
149 = return $ ImportDecl mod_name want_boot qual_only as_mod Nothing
150 rnImportDecl' iface decl_spec (ImportDecl mod_name want_boot qual_only as_mod (Just (want_hiding,import_items))) all_names
151 = do import_items_mbs <- mapM (srcSpanWrapper) import_items
152 let rn_import_items = concat . catMaybes $ import_items_mbs
153 return $ ImportDecl mod_name want_boot qual_only as_mod (Just (want_hiding,rn_import_items))
155 srcSpanWrapper (L span ieRdr)
156 = case get_item ieRdr of
158 -> do addErrAt span (badImportItemErr iface decl_spec ieRdr)
161 -> return (Just [L span ie | ie <- ieNames])
162 occ_env :: OccEnv Name -- Maps OccName to corresponding Name
163 occ_env = mkOccEnv [(nameOccName n, n) | n <- nameSetToList all_names]
164 -- This env will have entries for data constructors too,
165 -- they won't make any difference because naked entities like T
166 -- in an import list map to TcOccs, not VarOccs.
168 sub_env :: NameEnv [Name]
169 sub_env = mkSubNameEnv all_names
171 get_item :: IE RdrName -> Maybe [IE Name]
172 -- Empty result for a bad item.
173 -- Singleton result is typical case.
174 -- Can have two when we are hiding, and mention C which might be
175 -- both a class and a data constructor.
176 get_item item@(IEModuleContents _)
178 get_item (IEThingAll tc)
179 = do name <- check_name tc
180 return [IEThingAll name]
181 get_item (IEThingAbs tc)
182 | want_hiding -- hiding ( C )
183 -- Here the 'C' can be a data constructor
184 -- *or* a type/class, or even both
185 = case catMaybes [check_name tc, check_name (setRdrNameSpace tc srcDataName)] of
187 names -> return [ IEThingAbs n | n <- names ]
189 = do name <- check_name tc
190 return [IEThingAbs name]
191 get_item (IEThingWith n ns) -- import (C (A,B))
192 = do name <- check_name n
193 let env = mkOccEnv [(nameOccName s, s) | s <- subNames sub_env name]
194 mb_names = map (lookupOccEnv env . rdrNameOcc) ns
195 names <- sequence mb_names
196 return [IEThingWith name names]
198 = do name <- check_name n
201 check_name :: RdrName -> Maybe Name
203 = lookupOccEnv occ_env (rdrNameOcc rdrName)
206 importsFromImportDecl :: Module
208 -> RnM (GlobalRdrEnv, ImportAvails)
210 importsFromImportDecl this_mod
211 (L loc (ImportDecl loc_imp_mod_name want_boot qual_only as_mod imp_details))
215 -- If there's an error in loadInterface, (e.g. interface
216 -- file not found) we get lots of spurious errors from 'filterImports'
218 imp_mod_name = unLoc loc_imp_mod_name
219 doc = ppr imp_mod_name <+> ptext SLIT("is directly imported")
221 loadSrcInterface doc imp_mod_name want_boot `thenM` \ iface ->
223 -- Compiler sanity check: if the import didn't say
224 -- {-# SOURCE #-} we should not get a hi-boot file
225 WARN( not want_boot && mi_boot iface, ppr imp_mod_name )
227 -- Issue a user warning for a redundant {- SOURCE -} import
228 -- NB that we arrange to read all the ordinary imports before
229 -- any of the {- SOURCE -} imports
230 warnIf (want_boot && not (mi_boot iface))
231 (warnRedundantSourceImport imp_mod_name) `thenM_`
234 imp_mod = mi_module iface
235 deprecs = mi_deprecs iface
236 is_orph = mi_orphan iface
239 filtered_exports = filter not_this_mod (mi_exports iface)
240 not_this_mod (mod,_) = mod /= this_mod
241 -- If the module exports anything defined in this module, just ignore it.
242 -- Reason: otherwise it looks as if there are two local definition sites
243 -- for the thing, and an error gets reported. Easiest thing is just to
244 -- filter them out up front. This situation only arises if a module
245 -- imports itself, or another module that imported it. (Necessarily,
246 -- this invoves a loop.)
248 -- Tiresome consequence: if you say
253 -- module B( AType ) where
254 -- import {-# SOURCE #-} A( AType )
256 -- then you'll get a 'B does not export AType' message. Oh well.
258 qual_mod_name = case as_mod of
259 Nothing -> imp_mod_name
260 Just another_name -> another_name
261 imp_spec = ImpDeclSpec { is_mod = imp_mod_name, is_qual = qual_only,
262 is_dloc = loc, is_as = qual_mod_name }
264 -- Get the total imports, and filter them according to the import list
265 ifaceExportNames filtered_exports `thenM` \ total_avails ->
266 filterImports iface imp_spec
267 imp_details total_avails `thenM` \ (avail_env, gbl_env) ->
269 getDOpts `thenM` \ dflags ->
272 -- Compute new transitive dependencies
274 orphans | is_orph = ASSERT( not (imp_mod `elem` dep_orphs deps) )
275 imp_mod : dep_orphs deps
276 | otherwise = dep_orphs deps
278 pkg = modulePackageId (mi_module iface)
280 (dependent_mods, dependent_pkgs)
281 | pkg == thisPackage dflags =
282 -- Imported module is from the home package
283 -- Take its dependent modules and add imp_mod itself
284 -- Take its dependent packages unchanged
286 -- NB: (dep_mods deps) might include a hi-boot file
287 -- for the module being compiled, CM. Do *not* filter
288 -- this out (as we used to), because when we've
289 -- finished dealing with the direct imports we want to
290 -- know if any of them depended on CM.hi-boot, in
291 -- which case we should do the hi-boot consistency
292 -- check. See LoadIface.loadHiBootInterface
293 ((imp_mod_name, want_boot) : dep_mods deps, dep_pkgs deps)
296 -- Imported module is from another package
297 -- Dump the dependent modules
298 -- Add the package imp_mod comes from to the dependent packages
299 ASSERT2( not (pkg `elem` dep_pkgs deps), ppr pkg <+> ppr (dep_pkgs deps) )
300 ([], pkg : dep_pkgs deps)
302 -- True <=> import M ()
303 import_all = case imp_details of
304 Just (is_hiding, ls) -> not is_hiding && null ls
307 -- unqual_avails is the Avails that are visible in *unqualified* form
308 -- We need to know this so we know what to export when we see
309 -- module M ( module P ) where ...
310 -- Then we must export whatever came from P unqualified.
311 imports = ImportAvails {
312 imp_env = unitUFM qual_mod_name avail_env,
313 imp_mods = unitModuleEnv imp_mod (imp_mod, import_all, loc),
315 imp_dep_mods = mkModDeps dependent_mods,
316 imp_dep_pkgs = dependent_pkgs }
319 -- Complain if we import a deprecated module
320 ifOptM Opt_WarnDeprecations (
322 DeprecAll txt -> addWarn (moduleDeprec imp_mod_name txt)
326 returnM (gbl_env, imports)
328 warnRedundantSourceImport mod_name
329 = ptext SLIT("Unnecessary {-# SOURCE #-} in the import of module")
330 <+> quotes (ppr mod_name)
334 %************************************************************************
336 importsFromLocalDecls
338 %************************************************************************
340 From the top-level declarations of this module produce
341 * the lexical environment
343 created by its bindings.
345 Complain about duplicate bindings
348 importsFromLocalDecls :: HsGroup RdrName -> RnM TcGblEnv
349 importsFromLocalDecls group
350 = do { gbl_env <- getGblEnv
352 ; names <- getLocalDeclBinders gbl_env group
354 ; implicit_prelude <- doptM Opt_ImplicitPrelude
356 -- Optimisation: filter out names for built-in syntax
357 -- They just clutter up the environment (esp tuples), and the parser
358 -- will generate Exact RdrNames for them, so the cluttered
359 -- envt is no use. To avoid doing this filter all the time,
360 -- we use -fno-implicit-prelude as a clue that the filter is
361 -- worth while. Really, it's only useful for GHC.Base and GHC.Tuple.
363 -- It's worth doing because it makes the environment smaller for
364 -- every module that imports the Prelude
366 -- Note: don't filter the gbl_env (hence all_names, not filered_all_names
367 -- in defn of gres above). Stupid reason: when parsing
368 -- data type decls, the constructors start as Exact tycon-names,
369 -- and then get turned into data con names by zapping the name space;
370 -- but that stops them being Exact, so they get looked up.
371 -- Ditto in fixity decls; e.g. infix 5 :
372 -- Sigh. It doesn't matter because it only affects the Data.Tuple really.
373 -- The important thing is to trim down the exports.
375 | implicit_prelude = names
376 | otherwise = filter (not . isBuiltInSyntax) names ;
378 ; this_mod = tcg_mod gbl_env
379 ; imports = emptyImportAvails {
380 imp_env = unitUFM (moduleName this_mod) $
381 mkNameSet filtered_names
385 ; rdr_env' <- extendRdrEnvRn (tcg_rdr_env gbl_env) names
387 ; returnM (gbl_env { tcg_rdr_env = rdr_env',
388 tcg_imports = imports `plusImportAvails` tcg_imports gbl_env })
391 extendRdrEnvRn :: GlobalRdrEnv -> [Name] -> RnM GlobalRdrEnv
392 -- Add the new locally-bound names one by one, checking for duplicates as
393 -- we do so. Remember that in Template Haskell the duplicates
394 -- might *already be* in the GlobalRdrEnv from higher up the module
395 extendRdrEnvRn rdr_env names
396 = foldlM add_local rdr_env names
398 add_local rdr_env name
399 | gres <- lookupGlobalRdrEnv rdr_env (nameOccName name)
400 , (dup_gre:_) <- filter isLocalGRE gres -- Check for existing *local* defns
401 = do { addDupDeclErr (gre_name dup_gre) name
404 = return (extendGlobalRdrEnv rdr_env new_gre)
406 new_gre = GRE {gre_name = name, gre_prov = LocalDef}
409 @getLocalDeclBinders@ returns the names for an @HsDecl@. It's
410 used for source code.
412 *** See "THE NAMING STORY" in HsDecls ****
414 Associated data types: Instances declarations may contain definitions of
415 associated data types whose data constructors we need to collect, too.
416 However, we need to be careful with the handling of the data type constructor
417 of each asscociated type, as it is already defined in the corresponding
418 class. We make a new name for it, but don't return it in the 'AvailInfo' (to
419 avoid raising a duplicate declaration error; see the helper
420 'unavail_main_name').
423 getLocalDeclBinders :: TcGblEnv -> HsGroup RdrName -> RnM [Name]
424 getLocalDeclBinders gbl_env (HsGroup {hs_valds = ValBindsIn val_decls val_sigs,
425 hs_tyclds = tycl_decls,
426 hs_instds = inst_decls,
427 hs_fords = foreign_decls })
428 = do { tc_names_s <- mappM new_tc tycl_decls
429 ; at_names_s <- mappM inst_ats inst_decls
430 ; val_names <- mappM new_simple val_bndrs
431 ; return (foldr (++) val_names (tc_names_s ++ concat at_names_s)) }
433 mod = tcg_mod gbl_env
434 is_hs_boot = isHsBoot (tcg_src gbl_env) ;
435 val_bndrs | is_hs_boot = sig_hs_bndrs
436 | otherwise = for_hs_bndrs ++ val_hs_bndrs
437 -- In a hs-boot file, the value binders come from the
438 -- *signatures*, and there should be no foreign binders
440 new_simple rdr_name = newTopSrcBinder mod Nothing rdr_name
442 sig_hs_bndrs = [nm | L _ (TypeSig nm _) <- val_sigs]
443 val_hs_bndrs = collectHsBindLocatedBinders val_decls
444 for_hs_bndrs = [nm | L _ (ForeignImport nm _ _) <- foreign_decls]
447 = do { main_name <- newTopSrcBinder mod Nothing main_rdr
448 ; sub_names <- mappM (newTopSrcBinder mod (Just main_name)) sub_rdrs
449 ; return (main_name : sub_names) }
451 (main_rdr : sub_rdrs) = tyClDeclNames (unLoc tc_decl)
454 = mappM (liftM tail . new_tc) (instDeclATs (unLoc inst_decl))
455 -- drop main_rdr (already declared in class)
459 %************************************************************************
461 \subsection{Filtering imports}
463 %************************************************************************
465 @filterImports@ takes the @ExportEnv@ telling what the imported module makes
466 available, and filters it through the import spec (if any).
469 filterImports :: ModIface
470 -> ImpDeclSpec -- The span for the entire import decl
471 -> Maybe (Bool, [LIE Name]) -- Import spec; True => hiding
472 -> NameSet -- What's available
473 -> RnM (NameSet, -- What's imported (qualified or unqualified)
474 GlobalRdrEnv) -- Same again, but in GRE form
476 -- Complains if import spec mentions things that the module doesn't export
477 -- Warns/informs if import spec contains duplicates.
479 mkGenericRdrEnv decl_spec names
480 = mkGlobalRdrEnv [ GRE { gre_name = name, gre_prov = Imported [imp_spec] }
481 | name <- nameSetToList names ]
483 imp_spec = ImpSpec { is_decl = decl_spec, is_item = ImpAll }
485 filterImports iface decl_spec Nothing all_names
486 = return (all_names, mkGenericRdrEnv decl_spec all_names)
488 filterImports iface decl_spec (Just (want_hiding, import_items)) all_names
489 = mapM (addLocM get_item) import_items >>= \gres_s ->
490 let gres = concat gres_s
491 specified_names = mkNameSet (map gre_name gres)
492 in if not want_hiding then
493 return (specified_names, mkGlobalRdrEnv gres)
494 else let keep n = not (n `elemNameSet` specified_names)
495 pruned_avails = filterNameSet keep all_names
496 in return (pruned_avails, mkGenericRdrEnv decl_spec pruned_avails)
498 sub_env :: NameEnv [Name] -- Classify each name by its parent
499 sub_env = mkSubNameEnv all_names
501 succeed_with :: Bool -> [Name] -> RnM [GlobalRdrElt]
502 succeed_with all_explicit names
503 = do { loc <- getSrcSpanM
504 ; returnM (map (mk_gre loc) names) }
506 mk_gre loc name = GRE { gre_name = name,
507 gre_prov = Imported [imp_spec] }
509 imp_spec = ImpSpec { is_decl = decl_spec, is_item = item_spec }
510 item_spec = ImpSome { is_explicit = explicit, is_iloc = loc }
511 explicit = all_explicit || isNothing (nameParent_maybe name)
513 get_item :: IE Name -> RnM [GlobalRdrElt]
514 -- Empty result for a bad item.
515 -- Singleton result is typical case.
516 -- Can have two when we are hiding, and mention C which might be
517 -- both a class and a data constructor.
518 get_item item@(IEModuleContents _)
519 -- This case should be filtered out by 'rnImports'.
520 = panic "filterImports: IEModuleContents?"
522 get_item (IEThingAll name)
523 = case subNames sub_env name of
524 [] -> -- This occurs when you import T(..), but
525 -- only export T abstractly.
526 do ifOptM Opt_WarnDodgyImports (addWarn (dodgyImportWarn name))
527 succeed_with False [name]
528 names -> succeed_with False (name:names)
530 get_item (IEThingAbs name)
531 = succeed_with True [name]
533 get_item (IEThingWith name names)
534 = succeed_with True (name:names)
535 get_item (IEVar name)
536 = succeed_with True [name]
541 %************************************************************************
543 \subsection{Export list processing}
545 %************************************************************************
547 Processing the export list.
549 You might think that we should record things that appear in the export
550 list as ``occurrences'' (using @addOccurrenceName@), but you'd be
551 wrong. We do check (here) that they are in scope, but there is no
552 need to slurp in their actual declaration (which is what
553 @addOccurrenceName@ forces).
555 Indeed, doing so would big trouble when compiling @PrelBase@, because
556 it re-exports @GHC@, which includes @takeMVar#@, whose type includes
557 @ConcBase.StateAndSynchVar#@, and so on...
560 type ExportAccum -- The type of the accumulating parameter of
561 -- the main worker function in rnExports
562 = ([ModuleName], -- 'module M's seen so far
563 ExportOccMap, -- Tracks exported occurrence names
564 NameSet) -- The accumulated exported stuff
565 emptyExportAccum = ([], emptyOccEnv, emptyNameSet)
567 type ExportOccMap = OccEnv (Name, IE RdrName)
568 -- Tracks what a particular exported OccName
569 -- in an export list refers to, and which item
570 -- it came from. It's illegal to export two distinct things
571 -- that have the same occurrence name
573 rnExports :: Maybe [LIE RdrName]
574 -> RnM (Maybe [LIE Name])
575 rnExports Nothing = return Nothing
576 rnExports (Just exports)
577 = do TcGblEnv { tcg_imports = ImportAvails { imp_env = imp_env } } <- getGblEnv
578 let sub_env :: NameEnv [Name] -- Classify each name by its parent
579 sub_env = mkSubNameEnv (foldUFM unionNameSets emptyNameSet imp_env)
580 rnExport (IEVar rdrName)
581 = do name <- lookupGlobalOccRn rdrName
583 rnExport (IEThingAbs rdrName)
584 = do name <- lookupGlobalOccRn rdrName
585 return (IEThingAbs name)
586 rnExport (IEThingAll rdrName)
587 = do name <- lookupGlobalOccRn rdrName
588 return (IEThingAll name)
589 rnExport ie@(IEThingWith rdrName rdrNames)
590 = do name <- lookupGlobalOccRn rdrName
591 if isUnboundName name
592 then return (IEThingWith name [])
594 let env = mkOccEnv [(nameOccName s, s) | s <- subNames sub_env name]
595 mb_names = map (lookupOccEnv env . rdrNameOcc) rdrNames
596 if any isNothing mb_names
597 then do addErr (exportItemErr ie)
598 return (IEThingWith name [])
599 else return (IEThingWith name (catMaybes mb_names))
600 rnExport (IEModuleContents mod)
601 = return (IEModuleContents mod)
602 rn_exports <- mapM (wrapLocM rnExport) exports
603 return (Just rn_exports)
605 mkExportNameSet :: Bool -- False => no 'module M(..) where' header at all
606 -> Maybe ([LIE Name], [LIE RdrName]) -- Nothing => no explicit export list
608 -- Complains if two distinct exports have same OccName
609 -- Warns about identical exports.
610 -- Complains about exports items not in scope
612 mkExportNameSet explicit_mod exports
613 = do TcGblEnv { tcg_rdr_env = rdr_env,
614 tcg_imports = imports } <- getGblEnv
616 -- If the module header is omitted altogether, then behave
617 -- as if the user had written "module Main(main) where..."
618 -- EXCEPT in interactive mode, when we behave as if he had
619 -- written "module Main where ..."
620 -- Reason: don't want to complain about 'main' not in scope
621 -- in interactive mode
622 ghc_mode <- getGhcMode
623 real_exports <- case () of
626 | ghc_mode == Interactive
629 -> do mainName <- lookupGlobalOccRn main_RDR_Unqual
630 return (Just ([noLoc (IEVar mainName)]
631 ,[noLoc (IEVar main_RDR_Unqual)]))
632 -- ToDo: the 'noLoc' here is unhelpful if 'main' turns out to be out of scope
633 exports_from_avail real_exports rdr_env imports
636 exports_from_avail Nothing rdr_env imports
637 = -- Export all locally-defined things
638 -- We do this by filtering the global RdrEnv,
639 -- keeping only things that are locally-defined
640 return (mkNameSet [ gre_name gre
641 | gre <- globalRdrEnvElts rdr_env,
644 exports_from_avail (Just (items,origItems)) rdr_env (ImportAvails { imp_env = imp_env })
645 = do (_, _, exports) <- foldlM do_litem emptyExportAccum (zip items origItems)
648 sub_env :: NameEnv [Name] -- Classify each name by its parent
649 sub_env = mkSubNameEnv (foldUFM unionNameSets emptyNameSet imp_env)
651 do_litem :: ExportAccum -> (LIE Name, LIE RdrName) -> RnM ExportAccum
652 do_litem acc (ieName, ieRdr)
653 = addLocM (exports_from_item acc (unLoc ieRdr)) ieName
655 exports_from_item :: ExportAccum -> IE RdrName -> IE Name -> RnM ExportAccum
656 exports_from_item acc@(mods, occs, exports) ieRdr@(IEModuleContents mod) ie
657 | mod `elem` mods -- Duplicate export of M
658 = do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
659 warnIf warn_dup_exports (dupModuleExport mod) ;
663 = case lookupUFM imp_env mod of
664 Nothing -> do addErr (modExportErr mod)
667 -> do let new_exports = filterNameSet (inScopeUnqual rdr_env) names
668 -- This check_occs not only finds conflicts between this item
669 -- and others, but also internally within this item. That is,
670 -- if 'M.x' is in scope in several ways, we'll have several
671 -- members of mod_avails with the same OccName.
672 occs' <- check_occs ieRdr occs (nameSetToList new_exports)
673 return (mod:mods, occs', exports `unionNameSets` new_exports)
675 exports_from_item acc@(mods, occs, exports) ieRdr ie
676 = if isUnboundName (ieName ie)
677 then return acc -- Avoid error cascade
678 else let new_exports = filterAvail ie sub_env in
679 do -- checkErr (not (null (drop 1 new_exports))) (exportItemErr ie)
680 checkForDodgyExport ie new_exports
681 occs' <- check_occs ieRdr occs new_exports
682 return (mods, occs', addListToNameSet exports new_exports)
684 -------------------------------
685 filterAvail :: IE Name -- Wanted
686 -> NameEnv [Name] -- Maps type/class names to their sub-names
689 filterAvail (IEVar n) subs = [n]
690 filterAvail (IEThingAbs n) subs = [n]
691 filterAvail (IEThingAll n) subs = n : subNames subs n
692 filterAvail (IEThingWith n ns) subs = n : ns
693 filterAvail (IEModuleContents _) _ = panic "filterAvail"
695 subNames :: NameEnv [Name] -> Name -> [Name]
696 subNames env n = lookupNameEnv env n `orElse` []
698 mkSubNameEnv :: NameSet -> NameEnv [Name]
699 -- Maps types and classes to their constructors/classops respectively
700 -- This mapping just makes it easier to deal with A(..) export items
702 = foldNameSet add_name emptyNameEnv names
705 | Just parent <- nameParent_maybe name
706 = extendNameEnv_C (\ns _ -> name:ns) env parent [name]
709 -------------------------------
710 inScopeUnqual :: GlobalRdrEnv -> Name -> Bool
711 -- Checks whether the Name is in scope unqualified,
712 -- regardless of whether it's ambiguous or not
713 inScopeUnqual env n = any unQualOK (lookupGRE_Name env n)
715 -------------------------------
716 checkForDodgyExport :: IE Name -> [Name] -> RnM ()
717 checkForDodgyExport ie@(IEThingAll tc) [n]
718 | isTcOcc (nameOccName n) = addWarn (dodgyExportWarn tc)
719 -- This occurs when you export T(..), but
720 -- only import T abstractly, or T is a synonym.
721 -- The single [n] is the type or class itself
722 | otherwise = addErr (exportItemErr ie)
723 -- This happes if you export x(..), which is bogus
724 checkForDodgyExport _ _ = return ()
726 -------------------------------
727 check_occs :: IE RdrName -> ExportOccMap -> [Name] -> RnM ExportOccMap
728 check_occs ie occs names
729 = foldlM check occs names
732 = case lookupOccEnv occs name_occ of
733 Nothing -> returnM (extendOccEnv occs name_occ (name, ie))
736 | name == name' -- Duplicate export
737 -> do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
738 warnIf warn_dup_exports (dupExportWarn name_occ ie ie') ;
741 | otherwise -- Same occ name but different names: an error
742 -> do { global_env <- getGlobalRdrEnv ;
743 addErr (exportClashErr global_env name' name ie' ie) ;
746 name_occ = nameOccName name
749 %*********************************************************
753 %*********************************************************
756 reportDeprecations :: DynFlags -> TcGblEnv -> RnM ()
757 reportDeprecations dflags tcg_env
758 = ifOptM Opt_WarnDeprecations $
759 do { (eps,hpt) <- getEpsAndHpt
760 -- By this time, typechecking is complete,
761 -- so the PIT is fully populated
762 ; mapM_ (check hpt (eps_PIT eps)) all_gres }
764 used_names = allUses (tcg_dus tcg_env)
765 -- Report on all deprecated uses; hence allUses
766 all_gres = globalRdrEnvElts (tcg_rdr_env tcg_env)
768 check hpt pit (GRE {gre_name = name, gre_prov = Imported (imp_spec:_)})
769 | name `elemNameSet` used_names
770 , Just deprec_txt <- lookupDeprec dflags hpt pit name
771 = addWarnAt (importSpecLoc imp_spec)
772 (sep [ptext SLIT("Deprecated use of") <+>
773 pprNonVarNameSpace (occNameSpace (nameOccName name)) <+>
775 (parens imp_msg) <> colon,
778 name_mod = nameModule name
779 imp_mod = importSpecModule imp_spec
780 imp_msg = ptext SLIT("imported from") <+> ppr imp_mod <> extra
781 extra | imp_mod == moduleName name_mod = empty
782 | otherwise = ptext SLIT(", but defined in") <+> ppr name_mod
784 check hpt pit ok_gre = returnM () -- Local, or not used, or not deprectated
785 -- The Imported pattern-match: don't deprecate locally defined names
786 -- For a start, we may be exporting a deprecated thing
787 -- Also we may use a deprecated thing in the defn of another
788 -- deprecated things. We may even use a deprecated thing in
789 -- the defn of a non-deprecated thing, when changing a module's
792 lookupDeprec :: DynFlags -> HomePackageTable -> PackageIfaceTable
793 -> Name -> Maybe DeprecTxt
794 lookupDeprec dflags hpt pit n
795 = case lookupIfaceByModule dflags hpt pit (nameModule n) of
796 Just iface -> mi_dep_fn iface n `seqMaybe` -- Bleat if the thing, *or
797 mi_dep_fn iface (nameParent n) -- its parent*, is deprec'd
799 | isWiredInName n -> Nothing
800 -- We have not necessarily loaded the .hi file for a
801 -- wired-in name (yet), although we *could*.
802 -- And we never deprecate them
804 | otherwise -> pprPanic "lookupDeprec" (ppr n)
805 -- By now all the interfaces should have been loaded
807 gre_is_used :: NameSet -> GlobalRdrElt -> Bool
808 gre_is_used used_names gre = gre_name gre `elemNameSet` used_names
811 %*********************************************************
815 %*********************************************************
818 reportUnusedNames :: Maybe [LIE RdrName] -- Export list
819 -> TcGblEnv -> RnM ()
820 reportUnusedNames export_decls gbl_env
821 = do { traceRn ((text "RUN") <+> (ppr (tcg_dus gbl_env)))
822 ; warnUnusedTopBinds unused_locals
823 ; warnUnusedModules unused_imp_mods
824 ; warnUnusedImports unused_imports
825 ; warnDuplicateImports defined_and_used
826 ; printMinimalImports minimal_imports }
828 used_names, all_used_names :: NameSet
829 used_names = findUses (tcg_dus gbl_env) emptyNameSet
830 -- NB: currently, if f x = g, we only treat 'g' as used if 'f' is used
833 all_used_names = used_names `unionNameSets`
834 mkNameSet (mapCatMaybes nameParent_maybe (nameSetToList used_names))
835 -- A use of C implies a use of T,
836 -- if C was brought into scope by T(..) or T(C)
838 -- Collect the defined names from the in-scope environment
839 defined_names :: [GlobalRdrElt]
840 defined_names = globalRdrEnvElts (tcg_rdr_env gbl_env)
842 -- Note that defined_and_used, defined_but_not_used
843 -- are both [GRE]; that's why we need defined_and_used
844 -- rather than just all_used_names
845 defined_and_used, defined_but_not_used :: [GlobalRdrElt]
846 (defined_and_used, defined_but_not_used)
847 = partition (gre_is_used all_used_names) defined_names
849 -- Filter out the ones that are
850 -- (a) defined in this module, and
851 -- (b) not defined by a 'deriving' clause
852 -- The latter have an Internal Name, so we can filter them out easily
853 unused_locals :: [GlobalRdrElt]
854 unused_locals = filter is_unused_local defined_but_not_used
855 is_unused_local :: GlobalRdrElt -> Bool
856 is_unused_local gre = isLocalGRE gre && isExternalName (gre_name gre)
858 unused_imports :: [GlobalRdrElt]
859 unused_imports = filter unused_imp defined_but_not_used
860 unused_imp (GRE {gre_prov = Imported imp_specs})
861 = not (all (module_unused . importSpecModule) imp_specs)
862 && or [exp | ImpSpec { is_item = ImpSome { is_explicit = exp } } <- imp_specs]
863 -- Don't complain about unused imports if we've already said the
864 -- entire import is unused
865 unused_imp other = False
867 -- To figure out the minimal set of imports, start with the things
868 -- that are in scope (i.e. in gbl_env). Then just combine them
869 -- into a bunch of avails, so they are properly grouped
871 -- BUG WARNING: this does not deal properly with qualified imports!
872 minimal_imports :: FiniteMap ModuleName AvailEnv
873 minimal_imports0 = foldr add_expall emptyFM expall_mods
874 minimal_imports1 = foldr add_name minimal_imports0 defined_and_used
875 minimal_imports = foldr add_inst_mod minimal_imports1 direct_import_mods
876 -- The last line makes sure that we retain all direct imports
877 -- even if we import nothing explicitly.
878 -- It's not necessarily redundant to import such modules. Consider
882 -- The import M() is not *necessarily* redundant, even if
883 -- we suck in no instance decls from M (e.g. it contains
884 -- no instance decls, or This contains no code). It may be
885 -- that we import M solely to ensure that M's orphan instance
886 -- decls (or those in its imports) are visible to people who
887 -- import This. Sigh.
888 -- There's really no good way to detect this, so the error message
889 -- in RnEnv.warnUnusedModules is weakened instead
891 -- We've carefully preserved the provenance so that we can
892 -- construct minimal imports that import the name by (one of)
893 -- the same route(s) as the programmer originally did.
894 add_name (GRE {gre_name = n, gre_prov = Imported imp_specs}) acc
895 = addToFM_C plusAvailEnv acc (importSpecModule (head imp_specs))
896 (unitAvailEnv (mk_avail n (nameParent_maybe n)))
900 -- Modules mentioned as 'module M' in the export list
901 expall_mods = case export_decls of
903 Just es -> [m | L _ (IEModuleContents m) <- es]
905 -- This is really bogus. The idea is that if we see 'module M' in
906 -- the export list we must retain the import decls that drive it
907 -- If we aren't careful we might see
908 -- module A( module M ) where
911 -- and suppose that N exports everything that M does. Then we
912 -- must not drop the import of M even though N brings it all into
915 -- BUG WARNING: 'module M' exports aside, what if M.x is mentioned?!
917 -- The reason that add_expall is bogus is that it doesn't take
918 -- qualified imports into account. But it's an improvement.
919 add_expall mod acc = addToFM_C plusAvailEnv acc mod emptyAvailEnv
921 -- n is the name of the thing, p is the name of its parent
922 mk_avail n (Just p) = AvailTC p [p,n]
923 mk_avail n Nothing | isTcOcc (nameOccName n) = AvailTC n [n]
924 | otherwise = Avail n
926 add_inst_mod (mod,_,_) acc
927 | mod_name `elemFM` acc = acc -- We import something already
928 | otherwise = addToFM acc mod_name emptyAvailEnv
930 mod_name = moduleName mod
931 -- Add an empty collection of imports for a module
932 -- from which we have sucked only instance decls
934 imports = tcg_imports gbl_env
936 direct_import_mods :: [(Module, Bool, SrcSpan)]
937 -- See the type of the imp_mods for this triple
938 direct_import_mods = moduleEnvElts (imp_mods imports)
940 -- unused_imp_mods are the directly-imported modules
941 -- that are not mentioned in minimal_imports1
942 -- [Note: not 'minimal_imports', because that includes directly-imported
943 -- modules even if we use nothing from them; see notes above]
945 -- BUG WARNING: does not deal correctly with multiple imports of the same module
946 -- becuase direct_import_mods has only one entry per module
947 unused_imp_mods = [(mod_name,loc) | (mod,no_imp,loc) <- direct_import_mods,
948 let mod_name = moduleName mod,
949 not (mod_name `elemFM` minimal_imports1),
952 -- The not no_imp part is not to complain about
953 -- import M (), which is an idiom for importing
954 -- instance declarations
956 module_unused :: ModuleName -> Bool
957 module_unused mod = any (((==) mod) . fst) unused_imp_mods
959 ---------------------
960 warnDuplicateImports :: [GlobalRdrElt] -> RnM ()
961 -- Given the GREs for names that are used, figure out which imports
962 -- could be omitted without changing the top-level environment.
964 -- NB: Given import Foo( T )
965 -- import qualified Foo
966 -- we do not report a duplicate import, even though Foo.T is brought
967 -- into scope by both, because there's nothing you can *omit* without
968 -- changing the top-level environment. So we complain only if it's
969 -- explicitly named in both imports or neither.
971 -- Furthermore, we complain about Foo.T only if
972 -- there is no complaint about (unqualified) T
974 warnDuplicateImports gres
975 = ifOptM Opt_WarnUnusedImports $
976 sequenceM_ [ warn name pr
977 -- The 'head' picks the first offending group
978 -- for this particular name
979 | GRE { gre_name = name, gre_prov = Imported imps } <- gres
980 , pr <- redundants imps ]
982 warn name (red_imp, cov_imp)
983 = addWarnAt (importSpecLoc red_imp)
984 (vcat [ptext SLIT("Redundant import of:") <+> quotes pp_name,
985 ptext SLIT("It is also") <+> ppr cov_imp])
987 pp_name | is_qual red_decl = ppr (is_as red_decl) <> dot <> ppr occ
988 | otherwise = ppr occ
989 occ = nameOccName name
990 red_decl = is_decl red_imp
992 redundants :: [ImportSpec] -> [(ImportSpec,ImportSpec)]
993 -- The returned pair is (redundant-import, covering-import)
995 = [ (red_imp, cov_imp)
997 , cov_imp <- take 1 (filter (covers red_imp) imps) ]
999 -- "red_imp" is a putative redundant import
1000 -- "cov_imp" potentially covers it
1001 -- This test decides whether red_imp could be dropped
1003 -- NOTE: currently the test does not warn about
1006 -- even if the same underlying 'x' is involved, because dropping
1007 -- either import would change the qualified names in scope (M.x, N.x)
1008 -- But if the qualified names aren't used, the import is indeed redundant
1009 -- Sadly we don't know that. Oh well.
1010 covers red_imp@(ImpSpec { is_decl = red_decl, is_item = red_item })
1011 cov_imp@(ImpSpec { is_decl = cov_decl, is_item = cov_item })
1012 | red_loc == cov_loc
1013 = False -- Ignore diagonal elements
1014 | not (is_as red_decl == is_as cov_decl)
1015 = False -- They bring into scope different qualified names
1016 | not (is_qual red_decl) && is_qual cov_decl
1017 = False -- Covering one doesn't bring unqualified name into scope
1019 = not cov_selective -- Redundant one is selective and covering one isn't
1020 || red_later -- Both are explicit; tie-break using red_later
1022 = not cov_selective -- Neither import is selective
1023 && (is_mod red_decl == is_mod cov_decl) -- They import the same module
1024 && red_later -- Tie-break
1026 red_loc = importSpecLoc red_imp
1027 cov_loc = importSpecLoc cov_imp
1028 red_later = red_loc > cov_loc
1029 cov_selective = selectiveImpItem cov_item
1030 red_selective = selectiveImpItem red_item
1032 selectiveImpItem :: ImpItemSpec -> Bool
1033 selectiveImpItem ImpAll = False
1034 selectiveImpItem (ImpSome {}) = True
1036 -- ToDo: deal with original imports with 'qualified' and 'as M' clauses
1037 printMinimalImports :: FiniteMap ModuleName AvailEnv -- Minimal imports
1039 printMinimalImports imps
1040 = ifOptM Opt_D_dump_minimal_imports $ do {
1042 mod_ies <- mappM to_ies (fmToList imps) ;
1043 this_mod <- getModule ;
1044 rdr_env <- getGlobalRdrEnv ;
1045 ioToTcRn (do { h <- openFile (mkFilename this_mod) WriteMode ;
1046 printForUser h (mkPrintUnqualified rdr_env)
1047 (vcat (map ppr_mod_ie mod_ies)) })
1050 mkFilename this_mod = moduleNameString (moduleName this_mod) ++ ".imports"
1051 ppr_mod_ie (mod_name, ies)
1052 | mod_name == moduleName pRELUDE
1054 | null ies -- Nothing except instances comes from here
1055 = ptext SLIT("import") <+> ppr mod_name <> ptext SLIT("() -- Instances only")
1057 = ptext SLIT("import") <+> ppr mod_name <>
1058 parens (fsep (punctuate comma (map ppr ies)))
1060 to_ies (mod, avail_env) = do ies <- mapM to_ie (availEnvElts avail_env)
1063 to_ie :: AvailInfo -> RnM (IE Name)
1064 -- The main trick here is that if we're importing all the constructors
1065 -- we want to say "T(..)", but if we're importing only a subset we want
1066 -- to say "T(A,B,C)". So we have to find out what the module exports.
1067 to_ie (Avail n) = returnM (IEVar n)
1068 to_ie (AvailTC n [m]) = ASSERT( n==m )
1069 returnM (IEThingAbs n)
1070 to_ie (AvailTC n ns)
1071 = loadSrcInterface doc n_mod False `thenM` \ iface ->
1072 case [xs | (m,as) <- mi_exports iface,
1073 moduleName m == n_mod,
1075 x == nameOccName n] of
1076 [xs] | all_used xs -> returnM (IEThingAll n)
1077 | otherwise -> returnM (IEThingWith n (filter (/= n) ns))
1078 other -> pprTrace "to_ie" (ppr n <+> ppr n_mod <+> ppr other) $
1081 all_used avail_occs = all (`elem` map nameOccName ns) avail_occs
1082 doc = text "Compute minimal imports from" <+> ppr n
1083 n_mod = moduleName (nameModule n)
1087 %************************************************************************
1091 %************************************************************************
1094 badImportItemErr iface decl_spec ie
1095 = sep [ptext SLIT("Module"), quotes (ppr (is_mod decl_spec)), source_import,
1096 ptext SLIT("does not export"), quotes (ppr ie)]
1098 source_import | mi_boot iface = ptext SLIT("(hi-boot interface)")
1101 dodgyImportWarn item = dodgyMsg (ptext SLIT("import")) item
1102 dodgyExportWarn item = dodgyMsg (ptext SLIT("export")) item
1105 = sep [ ptext SLIT("The") <+> kind <+> ptext SLIT("item") <+> quotes (ppr (IEThingAll tc)),
1106 ptext SLIT("suggests that") <+> quotes (ppr tc) <+> ptext SLIT("has constructor or class methods"),
1107 ptext SLIT("but it has none; it is a type synonym or abstract type or class") ]
1110 = hsep [ ptext SLIT("Unknown module in export list: module"), quotes (ppr mod)]
1112 exportItemErr export_item
1113 = sep [ ptext SLIT("The export item") <+> quotes (ppr export_item),
1114 ptext SLIT("attempts to export constructors or class methods that are not visible here") ]
1116 exportClashErr global_env name1 name2 ie1 ie2
1117 = vcat [ ptext SLIT("Conflicting exports for") <+> quotes (ppr occ) <> colon
1118 , ppr_export ie1 name1
1119 , ppr_export ie2 name2 ]
1121 occ = nameOccName name1
1122 ppr_export ie name = nest 2 (quotes (ppr ie) <+> ptext SLIT("exports") <+>
1123 quotes (ppr name) <+> pprNameProvenance (get_gre name))
1125 -- get_gre finds a GRE for the Name, so that we can show its provenance
1127 = case lookupGRE_Name global_env name of
1129 [] -> pprPanic "exportClashErr" (ppr name)
1131 addDupDeclErr :: Name -> Name -> TcRn ()
1132 addDupDeclErr name_a name_b
1133 = addErrAt (srcLocSpan loc2) $
1134 vcat [ptext SLIT("Multiple declarations of") <+> quotes (ppr name1),
1135 ptext SLIT("Declared at:") <+> vcat [ppr (nameSrcLoc name1), ppr loc2]]
1137 loc2 = nameSrcLoc name2
1138 (name1,name2) | nameSrcLoc name_a > nameSrcLoc name_b = (name_b,name_a)
1139 | otherwise = (name_a,name_b)
1140 -- Report the error at the later location
1142 dupExportWarn occ_name ie1 ie2
1143 = hsep [quotes (ppr occ_name),
1144 ptext SLIT("is exported by"), quotes (ppr ie1),
1145 ptext SLIT("and"), quotes (ppr ie2)]
1148 = hsep [ptext SLIT("Duplicate"),
1149 quotes (ptext SLIT("Module") <+> ppr mod),
1150 ptext SLIT("in export list")]
1152 moduleDeprec mod txt
1153 = sep [ ptext SLIT("Module") <+> quotes (ppr mod) <+> ptext SLIT("is deprecated:"),