0bc6386427e84920ffdb7354e3af5f38290fb8d7
[ghc.git] / compiler / rename / RnNames.hs
1 {-
2 (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
3
4 \section[RnNames]{Extracting imported and top-level names in scope}
5 -}
6
7 {-# LANGUAGE CPP, NondecreasingIndentation #-}
8
9 module RnNames (
10 rnImports, getLocalNonValBinders, newRecordSelector,
11 rnExports, extendGlobalRdrEnvRn,
12 gresFromAvails,
13 calculateAvails,
14 reportUnusedNames,
15 checkConName
16 ) where
17
18 #include "HsVersions.h"
19
20 import DynFlags
21 import HsSyn
22 import TcEnv
23 import RnEnv
24 import RnHsDoc ( rnHsDoc )
25 import LoadIface ( loadSrcInterface )
26 import TcRnMonad
27 import PrelNames
28 import Module
29 import Name
30 import NameEnv
31 import NameSet
32 import Avail
33 import FieldLabel
34 import HscTypes
35 import RdrName
36 import RdrHsSyn ( setRdrNameSpace )
37 import Outputable
38 import Maybes
39 import SrcLoc
40 import BasicTypes ( TopLevelFlag(..), StringLiteral(..) )
41 import ErrUtils
42 import Util
43 import FastString
44 import FastStringEnv
45 import ListSetOps
46 import Id
47 import Type
48 import PatSyn
49 import qualified GHC.LanguageExtensions as LangExt
50
51 import Control.Monad
52 import Data.Either ( partitionEithers, isRight, rights )
53 -- import qualified Data.Foldable as Foldable
54 import Data.Map ( Map )
55 import qualified Data.Map as Map
56 import Data.Ord ( comparing )
57 import Data.List ( partition, (\\), find, sortBy )
58 -- import qualified Data.Set as Set
59 import System.FilePath ((</>))
60 import System.IO
61
62 {-
63 ************************************************************************
64 * *
65 \subsection{rnImports}
66 * *
67 ************************************************************************
68
69 Note [Tracking Trust Transitively]
70 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
71 When we import a package as well as checking that the direct imports are safe
72 according to the rules outlined in the Note [HscMain . Safe Haskell Trust Check]
73 we must also check that these rules hold transitively for all dependent modules
74 and packages. Doing this without caching any trust information would be very
75 slow as we would need to touch all packages and interface files a module depends
76 on. To avoid this we make use of the property that if a modules Safe Haskell
77 mode changes, this triggers a recompilation from that module in the dependcy
78 graph. So we can just worry mostly about direct imports.
79
80 There is one trust property that can change for a package though without
81 recompliation being triggered: package trust. So we must check that all
82 packages a module tranitively depends on to be trusted are still trusted when
83 we are compiling this module (as due to recompilation avoidance some modules
84 below may not be considered trusted any more without recompilation being
85 triggered).
86
87 We handle this by augmenting the existing transitive list of packages a module M
88 depends on with a bool for each package that says if it must be trusted when the
89 module M is being checked for trust. This list of trust required packages for a
90 single import is gathered in the rnImportDecl function and stored in an
91 ImportAvails data structure. The union of these trust required packages for all
92 imports is done by the rnImports function using the combine function which calls
93 the plusImportAvails function that is a union operation for the ImportAvails
94 type. This gives us in an ImportAvails structure all packages required to be
95 trusted for the module we are currently compiling. Checking that these packages
96 are still trusted (and that direct imports are trusted) is done in
97 HscMain.checkSafeImports.
98
99 See the note below, [Trust Own Package] for a corner case in this method and
100 how its handled.
101
102
103 Note [Trust Own Package]
104 ~~~~~~~~~~~~~~~~~~~~~~~~
105 There is a corner case of package trust checking that the usual transitive check
106 doesn't cover. (For how the usual check operates see the Note [Tracking Trust
107 Transitively] below). The case is when you import a -XSafe module M and M
108 imports a -XTrustworthy module N. If N resides in a different package than M,
109 then the usual check works as M will record a package dependency on N's package
110 and mark it as required to be trusted. If N resides in the same package as M
111 though, then importing M should require its own package be trusted due to N
112 (since M is -XSafe so doesn't create this requirement by itself). The usual
113 check fails as a module doesn't record a package dependency of its own package.
114 So instead we now have a bool field in a modules interface file that simply
115 states if the module requires its own package to be trusted. This field avoids
116 us having to load all interface files that the module depends on to see if one
117 is trustworthy.
118
119
120 Note [Trust Transitive Property]
121 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
122 So there is an interesting design question in regards to transitive trust
123 checking. Say I have a module B compiled with -XSafe. B is dependent on a bunch
124 of modules and packages, some packages it requires to be trusted as its using
125 -XTrustworthy modules from them. Now if I have a module A that doesn't use safe
126 haskell at all and simply imports B, should A inherit all the the trust
127 requirements from B? Should A now also require that a package p is trusted since
128 B required it?
129
130 We currently say no but saying yes also makes sense. The difference is, if a
131 module M that doesn't use Safe Haskell imports a module N that does, should all
132 the trusted package requirements be dropped since M didn't declare that it cares
133 about Safe Haskell (so -XSafe is more strongly associated with the module doing
134 the importing) or should it be done still since the author of the module N that
135 uses Safe Haskell said they cared (so -XSafe is more strongly associated with
136 the module that was compiled that used it).
137
138 Going with yes is a simpler semantics we think and harder for the user to stuff
139 up but it does mean that Safe Haskell will affect users who don't care about
140 Safe Haskell as they might grab a package from Cabal which uses safe haskell (say
141 network) and that packages imports -XTrustworthy modules from another package
142 (say bytestring), so requires that package is trusted. The user may now get
143 compilation errors in code that doesn't do anything with Safe Haskell simply
144 because they are using the network package. They will have to call 'ghc-pkg
145 trust network' to get everything working. Due to this invasive nature of going
146 with yes we have gone with no for now.
147 -}
148
149 -- | Process Import Decls. See 'rnImportDecl' for a description of what
150 -- the return types represent.
151 -- Note: Do the non SOURCE ones first, so that we get a helpful warning
152 -- for SOURCE ones that are unnecessary
153 rnImports :: [LImportDecl RdrName]
154 -> RnM ([LImportDecl Name], GlobalRdrEnv, ImportAvails, AnyHpcUsage)
155 rnImports imports = do
156 this_mod <- getModule
157 let (source, ordinary) = partition is_source_import imports
158 is_source_import d = ideclSource (unLoc d)
159 stuff1 <- mapAndReportM (rnImportDecl this_mod) ordinary
160 stuff2 <- mapAndReportM (rnImportDecl this_mod) source
161 -- Safe Haskell: See Note [Tracking Trust Transitively]
162 let (decls, rdr_env, imp_avails, hpc_usage) = combine (stuff1 ++ stuff2)
163 return (decls, rdr_env, imp_avails, hpc_usage)
164
165 where
166 combine :: [(LImportDecl Name, GlobalRdrEnv, ImportAvails, AnyHpcUsage)]
167 -> ([LImportDecl Name], GlobalRdrEnv, ImportAvails, AnyHpcUsage)
168 combine = foldr plus ([], emptyGlobalRdrEnv, emptyImportAvails, False)
169
170 plus (decl, gbl_env1, imp_avails1,hpc_usage1)
171 (decls, gbl_env2, imp_avails2,hpc_usage2)
172 = ( decl:decls,
173 gbl_env1 `plusGlobalRdrEnv` gbl_env2,
174 imp_avails1 `plusImportAvails` imp_avails2,
175 hpc_usage1 || hpc_usage2 )
176
177 -- | Given a located import declaration @decl@ from @this_mod@,
178 -- calculate the following pieces of information:
179 --
180 -- 1. An updated 'LImportDecl', where all unresolved 'RdrName' in
181 -- the entity lists have been resolved into 'Name's,
182 --
183 -- 2. A 'GlobalRdrEnv' representing the new identifiers that were
184 -- brought into scope (taking into account module qualification
185 -- and hiding),
186 --
187 -- 3. 'ImportAvails' summarizing the identifiers that were imported
188 -- by this declaration, and
189 --
190 -- 4. A boolean 'AnyHpcUsage' which is true if the imported module
191 -- used HPC.
192 rnImportDecl :: Module -> LImportDecl RdrName
193 -> RnM (LImportDecl Name, GlobalRdrEnv, ImportAvails, AnyHpcUsage)
194 rnImportDecl this_mod
195 (L loc decl@(ImportDecl { ideclName = loc_imp_mod_name, ideclPkgQual = mb_pkg
196 , ideclSource = want_boot, ideclSafe = mod_safe
197 , ideclQualified = qual_only, ideclImplicit = implicit
198 , ideclAs = as_mod, ideclHiding = imp_details }))
199 = setSrcSpan loc $ do
200
201 when (isJust mb_pkg) $ do
202 pkg_imports <- xoptM LangExt.PackageImports
203 when (not pkg_imports) $ addErr packageImportErr
204
205 -- If there's an error in loadInterface, (e.g. interface
206 -- file not found) we get lots of spurious errors from 'filterImports'
207 let imp_mod_name = unLoc loc_imp_mod_name
208 doc = ppr imp_mod_name <+> text "is directly imported"
209
210 -- Check for self-import, which confuses the typechecker (Trac #9032)
211 -- ghc --make rejects self-import cycles already, but batch-mode may not
212 -- at least not until TcIface.tcHiBootIface, which is too late to avoid
213 -- typechecker crashes. (Indirect self imports are not caught until
214 -- TcIface, see #10337 tracking how to make this error better.)
215 --
216 -- Originally, we also allowed 'import {-# SOURCE #-} M', but this
217 -- caused bug #10182: in one-shot mode, we should never load an hs-boot
218 -- file for the module we are compiling into the EPS. In principle,
219 -- it should be possible to support this mode of use, but we would have to
220 -- extend Provenance to support a local definition in a qualified location.
221 -- For now, we don't support it, but see #10336
222 when (imp_mod_name == moduleName this_mod &&
223 (case mb_pkg of -- If we have import "<pkg>" M, then we should
224 -- check that "<pkg>" is "this" (which is magic)
225 -- or the name of this_mod's package. Yurgh!
226 -- c.f. GHC.findModule, and Trac #9997
227 Nothing -> True
228 Just (StringLiteral _ pkg_fs) -> pkg_fs == fsLit "this" ||
229 fsToUnitId pkg_fs == moduleUnitId this_mod))
230 (addErr (text "A module cannot import itself:" <+> ppr imp_mod_name))
231
232 -- Check for a missing import list (Opt_WarnMissingImportList also
233 -- checks for T(..) items but that is done in checkDodgyImport below)
234 case imp_details of
235 Just (False, _) -> return () -- Explicit import list
236 _ | implicit -> return () -- Do not bleat for implicit imports
237 | qual_only -> return ()
238 | otherwise -> whenWOptM Opt_WarnMissingImportList $
239 addWarn (Reason Opt_WarnMissingImportList)
240 (missingImportListWarn imp_mod_name)
241
242 iface <- loadSrcInterface doc imp_mod_name want_boot (fmap sl_fs mb_pkg)
243
244 -- Compiler sanity check: if the import didn't say
245 -- {-# SOURCE #-} we should not get a hi-boot file
246 WARN( not want_boot && mi_boot iface, ppr imp_mod_name ) do
247
248 -- Issue a user warning for a redundant {- SOURCE -} import
249 -- NB that we arrange to read all the ordinary imports before
250 -- any of the {- SOURCE -} imports.
251 --
252 -- in --make and GHCi, the compilation manager checks for this,
253 -- and indeed we shouldn't do it here because the existence of
254 -- the non-boot module depends on the compilation order, which
255 -- is not deterministic. The hs-boot test can show this up.
256 dflags <- getDynFlags
257 warnIf NoReason
258 (want_boot && not (mi_boot iface) && isOneShot (ghcMode dflags))
259 (warnRedundantSourceImport imp_mod_name)
260 when (mod_safe && not (safeImportsOn dflags)) $
261 addErr (text "safe import can't be used as Safe Haskell isn't on!"
262 $+$ ptext (sLit $ "please enable Safe Haskell through either "
263 ++ "Safe, Trustworthy or Unsafe"))
264
265 let
266 qual_mod_name = as_mod `orElse` imp_mod_name
267 imp_spec = ImpDeclSpec { is_mod = imp_mod_name, is_qual = qual_only,
268 is_dloc = loc, is_as = qual_mod_name }
269
270 -- filter the imports according to the import declaration
271 (new_imp_details, gres) <- filterImports iface imp_spec imp_details
272
273 -- for certain error messages, we’d like to know what could be imported
274 -- here, if everything were imported
275 potential_gres <- mkGlobalRdrEnv . snd <$> filterImports iface imp_spec Nothing
276
277 let gbl_env = mkGlobalRdrEnv gres
278
279 is_hiding | Just (True,_) <- imp_details = True
280 | otherwise = False
281
282 -- should the import be safe?
283 mod_safe' = mod_safe
284 || (not implicit && safeDirectImpsReq dflags)
285 || (implicit && safeImplicitImpsReq dflags)
286
287 let imv = ImportedModsVal
288 { imv_name = qual_mod_name
289 , imv_span = loc
290 , imv_is_safe = mod_safe'
291 , imv_is_hiding = is_hiding
292 , imv_all_exports = potential_gres
293 , imv_qualified = qual_only
294 }
295 let imports
296 = (calculateAvails dflags iface mod_safe' want_boot)
297 { imp_mods = unitModuleEnv (mi_module iface) [imv] }
298
299 -- Complain if we import a deprecated module
300 whenWOptM Opt_WarnWarningsDeprecations (
301 case (mi_warns iface) of
302 WarnAll txt -> addWarn (Reason Opt_WarnWarningsDeprecations)
303 (moduleWarn imp_mod_name txt)
304 _ -> return ()
305 )
306
307 let new_imp_decl = L loc (decl { ideclSafe = mod_safe'
308 , ideclHiding = new_imp_details })
309
310 return (new_imp_decl, gbl_env, imports, mi_hpc iface)
311
312 -- | Calculate the 'ImportAvails' induced by an import of a particular
313 -- interface, but without 'imp_mods'.
314 calculateAvails :: DynFlags
315 -> ModIface
316 -> IsSafeImport
317 -> IsBootInterface
318 -> ImportAvails
319 calculateAvails dflags iface mod_safe' want_boot =
320 let imp_mod = mi_module iface
321 orph_iface = mi_orphan iface
322 has_finsts = mi_finsts iface
323 deps = mi_deps iface
324 trust = getSafeMode $ mi_trust iface
325 trust_pkg = mi_trust_pkg iface
326
327 -- If the module exports anything defined in this module, just
328 -- ignore it. Reason: otherwise it looks as if there are two
329 -- local definition sites for the thing, and an error gets
330 -- reported. Easiest thing is just to filter them out up
331 -- front. This situation only arises if a module imports
332 -- itself, or another module that imported it. (Necessarily,
333 -- this invoves a loop.)
334 --
335 -- We do this *after* filterImports, so that if you say
336 -- module A where
337 -- import B( AType )
338 -- type AType = ...
339 --
340 -- module B( AType ) where
341 -- import {-# SOURCE #-} A( AType )
342 --
343 -- then you won't get a 'B does not export AType' message.
344
345
346 -- Compute new transitive dependencies
347
348 orphans | orph_iface = ASSERT( not (imp_mod `elem` dep_orphs deps) )
349 imp_mod : dep_orphs deps
350 | otherwise = dep_orphs deps
351
352 finsts | has_finsts = ASSERT( not (imp_mod `elem` dep_finsts deps) )
353 imp_mod : dep_finsts deps
354 | otherwise = dep_finsts deps
355
356 pkg = moduleUnitId (mi_module iface)
357
358 -- Does this import mean we now require our own pkg
359 -- to be trusted? See Note [Trust Own Package]
360 ptrust = trust == Sf_Trustworthy || trust_pkg
361
362 (dependent_mods, dependent_pkgs, pkg_trust_req)
363 | pkg == thisPackage dflags =
364 -- Imported module is from the home package
365 -- Take its dependent modules and add imp_mod itself
366 -- Take its dependent packages unchanged
367 --
368 -- NB: (dep_mods deps) might include a hi-boot file
369 -- for the module being compiled, CM. Do *not* filter
370 -- this out (as we used to), because when we've
371 -- finished dealing with the direct imports we want to
372 -- know if any of them depended on CM.hi-boot, in
373 -- which case we should do the hi-boot consistency
374 -- check. See LoadIface.loadHiBootInterface
375 ((moduleName imp_mod,want_boot):dep_mods deps,dep_pkgs deps,ptrust)
376
377 | otherwise =
378 -- Imported module is from another package
379 -- Dump the dependent modules
380 -- Add the package imp_mod comes from to the dependent packages
381 ASSERT2( not (pkg `elem` (map fst $ dep_pkgs deps))
382 , ppr pkg <+> ppr (dep_pkgs deps) )
383 ([], (pkg, False) : dep_pkgs deps, False)
384
385 in ImportAvails {
386 imp_mods = emptyModuleEnv, -- this gets filled in later
387 imp_orphs = orphans,
388 imp_finsts = finsts,
389 imp_dep_mods = mkModDeps dependent_mods,
390 imp_dep_pkgs = map fst $ dependent_pkgs,
391 -- Add in the imported modules trusted package
392 -- requirements. ONLY do this though if we import the
393 -- module as a safe import.
394 -- See Note [Tracking Trust Transitively]
395 -- and Note [Trust Transitive Property]
396 imp_trust_pkgs = if mod_safe'
397 then map fst $ filter snd dependent_pkgs
398 else [],
399 -- Do we require our own pkg to be trusted?
400 -- See Note [Trust Own Package]
401 imp_trust_own_pkg = pkg_trust_req
402 }
403
404
405 warnRedundantSourceImport :: ModuleName -> SDoc
406 warnRedundantSourceImport mod_name
407 = text "Unnecessary {-# SOURCE #-} in the import of module"
408 <+> quotes (ppr mod_name)
409
410 {-
411 ************************************************************************
412 * *
413 \subsection{importsFromLocalDecls}
414 * *
415 ************************************************************************
416
417 From the top-level declarations of this module produce
418 * the lexical environment
419 * the ImportAvails
420 created by its bindings.
421
422 Note [Top-level Names in Template Haskell decl quotes]
423 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
424 See also: Note [Interactively-bound Ids in GHCi] in HscTypes
425 Note [Looking up Exact RdrNames] in RnEnv
426
427 Consider a Template Haskell declaration quotation like this:
428 module M where
429 f x = h [d| f = 3 |]
430 When renaming the declarations inside [d| ...|], we treat the
431 top level binders specially in two ways
432
433 1. We give them an Internal Name, not (as usual) an External one.
434 This is done by RnEnv.newTopSrcBinder.
435
436 2. We make them *shadow* the outer bindings.
437 See Note [GlobalRdrEnv shadowing]
438
439 3. We find out whether we are inside a [d| ... |] by testing the TH
440 stage. This is a slight hack, because the stage field was really
441 meant for the type checker, and here we are not interested in the
442 fields of Brack, hence the error thunks in thRnBrack.
443 -}
444
445 extendGlobalRdrEnvRn :: [AvailInfo]
446 -> MiniFixityEnv
447 -> RnM (TcGblEnv, TcLclEnv)
448 -- Updates both the GlobalRdrEnv and the FixityEnv
449 -- We return a new TcLclEnv only because we might have to
450 -- delete some bindings from it;
451 -- see Note [Top-level Names in Template Haskell decl quotes]
452
453 extendGlobalRdrEnvRn avails new_fixities
454 = do { (gbl_env, lcl_env) <- getEnvs
455 ; stage <- getStage
456 ; isGHCi <- getIsGHCi
457 ; let rdr_env = tcg_rdr_env gbl_env
458 fix_env = tcg_fix_env gbl_env
459 th_bndrs = tcl_th_bndrs lcl_env
460 th_lvl = thLevel stage
461
462 -- Delete new_occs from global and local envs
463 -- If we are in a TemplateHaskell decl bracket,
464 -- we are going to shadow them
465 -- See Note [GlobalRdrEnv shadowing]
466 inBracket = isBrackStage stage
467
468 lcl_env_TH = lcl_env { tcl_rdr = delLocalRdrEnvList (tcl_rdr lcl_env) new_occs }
469 -- See Note [GlobalRdrEnv shadowing]
470
471 lcl_env2 | inBracket = lcl_env_TH
472 | otherwise = lcl_env
473
474 -- Deal with shadowing: see Note [GlobalRdrEnv shadowing]
475 want_shadowing = isGHCi || inBracket
476 rdr_env1 | want_shadowing = shadowNames rdr_env new_names
477 | otherwise = rdr_env
478
479 lcl_env3 = lcl_env2 { tcl_th_bndrs = extendNameEnvList th_bndrs
480 [ (n, (TopLevel, th_lvl))
481 | n <- new_names ] }
482
483 ; rdr_env2 <- foldlM add_gre rdr_env1 new_gres
484
485 ; let fix_env' = foldl extend_fix_env fix_env new_gres
486 gbl_env' = gbl_env { tcg_rdr_env = rdr_env2, tcg_fix_env = fix_env' }
487
488 ; traceRn (text "extendGlobalRdrEnvRn 2" <+> (pprGlobalRdrEnv True rdr_env2))
489 ; return (gbl_env', lcl_env3) }
490 where
491 new_names = concatMap availNames avails
492 new_occs = map nameOccName new_names
493
494 -- If there is a fixity decl for the gre, add it to the fixity env
495 extend_fix_env fix_env gre
496 | Just (L _ fi) <- lookupFsEnv new_fixities (occNameFS occ)
497 = extendNameEnv fix_env name (FixItem occ fi)
498 | otherwise
499 = fix_env
500 where
501 name = gre_name gre
502 occ = greOccName gre
503
504 new_gres :: [GlobalRdrElt] -- New LocalDef GREs, derived from avails
505 new_gres = concatMap localGREsFromAvail avails
506
507 add_gre :: GlobalRdrEnv -> GlobalRdrElt -> RnM GlobalRdrEnv
508 -- Extend the GlobalRdrEnv with a LocalDef GRE
509 -- If there is already a LocalDef GRE with the same OccName,
510 -- report an error and discard the new GRE
511 -- This establishes INVARIANT 1 of GlobalRdrEnvs
512 add_gre env gre
513 | not (null dups) -- Same OccName defined twice
514 = do { addDupDeclErr (gre : dups); return env }
515
516 | otherwise
517 = return (extendGlobalRdrEnv env gre)
518 where
519 name = gre_name gre
520 occ = nameOccName name
521 dups = filter isLocalGRE (lookupGlobalRdrEnv env occ)
522
523
524 {- *********************************************************************
525 * *
526 getLocalDeclBindersd@ returns the names for an HsDecl
527 It's used for source code.
528
529 *** See "THE NAMING STORY" in HsDecls ****
530 * *
531 ********************************************************************* -}
532
533 getLocalNonValBinders :: MiniFixityEnv -> HsGroup RdrName
534 -> RnM ((TcGblEnv, TcLclEnv), NameSet)
535 -- Get all the top-level binders bound the group *except*
536 -- for value bindings, which are treated separately
537 -- Specifically we return AvailInfo for
538 -- * type decls (incl constructors and record selectors)
539 -- * class decls (including class ops)
540 -- * associated types
541 -- * foreign imports
542 -- * value signatures (in hs-boot files only)
543
544 getLocalNonValBinders fixity_env
545 (HsGroup { hs_valds = binds,
546 hs_tyclds = tycl_decls,
547 hs_instds = inst_decls,
548 hs_fords = foreign_decls })
549 = do { -- Process all type/class decls *except* family instances
550 ; overload_ok <- xoptM LangExt.DuplicateRecordFields
551 ; (tc_avails, tc_fldss) <- fmap unzip $ mapM (new_tc overload_ok)
552 (tyClGroupConcat tycl_decls)
553 ; traceRn (text "getLocalNonValBinders 1" <+> ppr tc_avails)
554 ; envs <- extendGlobalRdrEnvRn tc_avails fixity_env
555 ; setEnvs envs $ do {
556 -- Bring these things into scope first
557 -- See Note [Looking up family names in family instances]
558
559 -- Process all family instances
560 -- to bring new data constructors into scope
561 ; (nti_availss, nti_fldss) <- mapAndUnzipM (new_assoc overload_ok)
562 inst_decls
563
564 -- Finish off with value binders:
565 -- foreign decls and pattern synonyms for an ordinary module
566 -- type sigs in case of a hs-boot file only
567 ; is_boot <- tcIsHsBootOrSig
568 ; let val_bndrs | is_boot = hs_boot_sig_bndrs
569 | otherwise = for_hs_bndrs
570 ; val_avails <- mapM new_simple val_bndrs
571
572 ; let avails = concat nti_availss ++ val_avails
573 new_bndrs = availsToNameSetWithSelectors avails `unionNameSet`
574 availsToNameSetWithSelectors tc_avails
575 flds = concat nti_fldss ++ concat tc_fldss
576 ; traceRn (text "getLocalNonValBinders 2" <+> ppr avails)
577 ; (tcg_env, tcl_env) <- extendGlobalRdrEnvRn avails fixity_env
578
579 -- Extend tcg_field_env with new fields (this used to be the
580 -- work of extendRecordFieldEnv)
581 ; let field_env = extendNameEnvList (tcg_field_env tcg_env) flds
582 envs = (tcg_env { tcg_field_env = field_env }, tcl_env)
583
584 ; traceRn (text "getLocalNonValBinders 3" <+> vcat [ppr flds, ppr field_env])
585 ; return (envs, new_bndrs) } }
586 where
587 ValBindsIn _val_binds val_sigs = binds
588
589 for_hs_bndrs :: [Located RdrName]
590 for_hs_bndrs = hsForeignDeclsBinders foreign_decls
591
592 -- In a hs-boot file, the value binders come from the
593 -- *signatures*, and there should be no foreign binders
594 hs_boot_sig_bndrs = [ L decl_loc (unLoc n)
595 | L decl_loc (TypeSig ns _) <- val_sigs, n <- ns]
596
597 -- the SrcSpan attached to the input should be the span of the
598 -- declaration, not just the name
599 new_simple :: Located RdrName -> RnM AvailInfo
600 new_simple rdr_name = do{ nm <- newTopSrcBinder rdr_name
601 ; return (avail nm) }
602
603 new_tc :: Bool -> LTyClDecl RdrName
604 -> RnM (AvailInfo, [(Name, [FieldLabel])])
605 new_tc overload_ok tc_decl -- NOT for type/data instances
606 = do { let (bndrs, flds) = hsLTyClDeclBinders tc_decl
607 ; names@(main_name : sub_names) <- mapM newTopSrcBinder bndrs
608 ; flds' <- mapM (newRecordSelector overload_ok sub_names) flds
609 ; let fld_env = case unLoc tc_decl of
610 DataDecl { tcdDataDefn = d } -> mk_fld_env d names flds'
611 _ -> []
612 ; return (AvailTC main_name names flds', fld_env) }
613
614
615 -- Calculate the mapping from constructor names to fields, which
616 -- will go in tcg_field_env. It's convenient to do this here where
617 -- we are working with a single datatype definition.
618 mk_fld_env :: HsDataDefn RdrName -> [Name] -> [FieldLabel] -> [(Name, [FieldLabel])]
619 mk_fld_env d names flds = concatMap find_con_flds (dd_cons d)
620 where
621 find_con_flds (L _ (ConDeclH98 { con_name = L _ rdr
622 , con_details = RecCon cdflds }))
623 = [( find_con_name rdr
624 , concatMap find_con_decl_flds (unLoc cdflds) )]
625 find_con_flds (L _ (ConDeclGADT
626 { con_names = rdrs
627 , con_type = (HsIB { hsib_body = res_ty})}))
628 = map (\ (L _ rdr) -> ( find_con_name rdr
629 , concatMap find_con_decl_flds cdflds))
630 rdrs
631 where
632 (_tvs, _cxt, tau) = splitLHsSigmaTy res_ty
633 cdflds = case tau of
634 L _ (HsFunTy
635 (L _ (HsAppsTy
636 [L _ (HsAppPrefix (L _ (HsRecTy flds)))])) _) -> flds
637 L _ (HsFunTy (L _ (HsRecTy flds)) _) -> flds
638 _ -> []
639 find_con_flds _ = []
640
641 find_con_name rdr
642 = expectJust "getLocalNonValBinders/find_con_name" $
643 find (\ n -> nameOccName n == rdrNameOcc rdr) names
644 find_con_decl_flds (L _ x)
645 = map find_con_decl_fld (cd_fld_names x)
646 find_con_decl_fld (L _ (FieldOcc (L _ rdr) _))
647 = expectJust "getLocalNonValBinders/find_con_decl_fld" $
648 find (\ fl -> flLabel fl == lbl) flds
649 where lbl = occNameFS (rdrNameOcc rdr)
650
651 new_assoc :: Bool -> LInstDecl RdrName
652 -> RnM ([AvailInfo], [(Name, [FieldLabel])])
653 new_assoc _ (L _ (TyFamInstD {})) = return ([], [])
654 -- type instances don't bind new names
655
656 new_assoc overload_ok (L _ (DataFamInstD d))
657 = do { (avail, flds) <- new_di overload_ok Nothing d
658 ; return ([avail], flds) }
659 new_assoc overload_ok (L _ (ClsInstD (ClsInstDecl { cid_poly_ty = inst_ty
660 , cid_datafam_insts = adts })))
661 | Just (L loc cls_rdr) <- getLHsInstDeclClass_maybe inst_ty
662 = do { cls_nm <- setSrcSpan loc $ lookupGlobalOccRn cls_rdr
663 ; (avails, fldss)
664 <- mapAndUnzipM (new_loc_di overload_ok (Just cls_nm)) adts
665 ; return (avails, concat fldss) }
666 | otherwise
667 = return ([], []) -- Do not crash on ill-formed instances
668 -- Eg instance !Show Int Trac #3811c
669
670 new_di :: Bool -> Maybe Name -> DataFamInstDecl RdrName
671 -> RnM (AvailInfo, [(Name, [FieldLabel])])
672 new_di overload_ok mb_cls ti_decl
673 = do { main_name <- lookupFamInstName mb_cls (dfid_tycon ti_decl)
674 ; let (bndrs, flds) = hsDataFamInstBinders ti_decl
675 ; sub_names <- mapM newTopSrcBinder bndrs
676 ; flds' <- mapM (newRecordSelector overload_ok sub_names) flds
677 ; let avail = AvailTC (unLoc main_name) sub_names flds'
678 -- main_name is not bound here!
679 fld_env = mk_fld_env (dfid_defn ti_decl) sub_names flds'
680 ; return (avail, fld_env) }
681
682 new_loc_di :: Bool -> Maybe Name -> LDataFamInstDecl RdrName
683 -> RnM (AvailInfo, [(Name, [FieldLabel])])
684 new_loc_di overload_ok mb_cls (L _ d) = new_di overload_ok mb_cls d
685
686 newRecordSelector :: Bool -> [Name] -> LFieldOcc RdrName -> RnM FieldLabel
687 newRecordSelector _ [] _ = error "newRecordSelector: datatype has no constructors!"
688 newRecordSelector overload_ok (dc:_) (L loc (FieldOcc (L _ fld) _))
689 = do { selName <- newTopSrcBinder $ L loc $ field
690 ; return $ qualFieldLbl { flSelector = selName } }
691 where
692 fieldOccName = occNameFS $ rdrNameOcc fld
693 qualFieldLbl = mkFieldLabelOccs fieldOccName (nameOccName dc) overload_ok
694 field | isExact fld = fld
695 -- use an Exact RdrName as is to preserve the bindings
696 -- of an already renamer-resolved field and its use
697 -- sites. This is needed to correctly support record
698 -- selectors in Template Haskell. See Note [Binders in
699 -- Template Haskell] in Convert.hs and Note [Looking up
700 -- Exact RdrNames] in RnEnv.hs.
701 | otherwise = mkRdrUnqual (flSelector qualFieldLbl)
702
703 {-
704 Note [Looking up family names in family instances]
705 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
706 Consider
707
708 module M where
709 type family T a :: *
710 type instance M.T Int = Bool
711
712 We might think that we can simply use 'lookupOccRn' when processing the type
713 instance to look up 'M.T'. Alas, we can't! The type family declaration is in
714 the *same* HsGroup as the type instance declaration. Hence, as we are
715 currently collecting the binders declared in that HsGroup, these binders will
716 not have been added to the global environment yet.
717
718 Solution is simple: process the type family declarations first, extend
719 the environment, and then process the type instances.
720
721
722 ************************************************************************
723 * *
724 \subsection{Filtering imports}
725 * *
726 ************************************************************************
727
728 @filterImports@ takes the @ExportEnv@ telling what the imported module makes
729 available, and filters it through the import spec (if any).
730
731 Note [Dealing with imports]
732 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
733 For import M( ies ), we take the mi_exports of M, and make
734 imp_occ_env :: OccEnv (Name, AvailInfo, Maybe Name)
735 One entry for each Name that M exports; the AvailInfo describes just
736 that Name.
737
738 The situation is made more complicated by associated types. E.g.
739 module M where
740 class C a where { data T a }
741 instance C Int where { data T Int = T1 | T2 }
742 instance C Bool where { data T Int = T3 }
743 Then M's export_avails are (recall the AvailTC invariant from Avails.hs)
744 C(C,T), T(T,T1,T2,T3)
745 Notice that T appears *twice*, once as a child and once as a parent.
746 From this we construct the imp_occ_env
747 C -> (C, C(C,T), Nothing)
748 T -> (T, T(T,T1,T2,T3), Just C)
749 T1 -> (T1, T(T1,T2,T3), Nothing) -- similarly T2,T3
750
751 If we say
752 import M( T(T1,T2) )
753 then we get *two* Avails: C(T), T(T1,T2)
754
755 Note that the imp_occ_env will have entries for data constructors too,
756 although we never look up data constructors.
757 -}
758
759 filterImports
760 :: ModIface
761 -> ImpDeclSpec -- The span for the entire import decl
762 -> Maybe (Bool, Located [LIE RdrName]) -- Import spec; True => hiding
763 -> RnM (Maybe (Bool, Located [LIE Name]), -- Import spec w/ Names
764 [GlobalRdrElt]) -- Same again, but in GRE form
765 filterImports iface decl_spec Nothing
766 = return (Nothing, gresFromAvails (Just imp_spec) (mi_exports iface))
767 where
768 imp_spec = ImpSpec { is_decl = decl_spec, is_item = ImpAll }
769
770
771 filterImports iface decl_spec (Just (want_hiding, L l import_items))
772 = do -- check for errors, convert RdrNames to Names
773 items1 <- mapM lookup_lie import_items
774
775 let items2 :: [(LIE Name, AvailInfo)]
776 items2 = concat items1
777 -- NB the AvailInfo may have duplicates, and several items
778 -- for the same parent; e.g N(x) and N(y)
779
780 names = availsToNameSet (map snd items2)
781 keep n = not (n `elemNameSet` names)
782 pruned_avails = filterAvails keep all_avails
783 hiding_spec = ImpSpec { is_decl = decl_spec, is_item = ImpAll }
784
785 gres | want_hiding = gresFromAvails (Just hiding_spec) pruned_avails
786 | otherwise = concatMap (gresFromIE decl_spec) items2
787
788 return (Just (want_hiding, L l (map fst items2)), gres)
789 where
790 all_avails = mi_exports iface
791
792 -- See Note [Dealing with imports]
793 imp_occ_env :: OccEnv (Name, -- the name
794 AvailInfo, -- the export item providing the name
795 Maybe Name) -- the parent of associated types
796 imp_occ_env = mkOccEnv_C combine [ (nameOccName n, (n, a, Nothing))
797 | a <- all_avails, n <- availNames a]
798 where
799 -- See example in Note [Dealing with imports]
800 -- 'combine' is only called for associated types which appear twice
801 -- in the all_avails. In the example, we combine
802 -- T(T,T1,T2,T3) and C(C,T) to give (T, T(T,T1,T2,T3), Just C)
803 combine (name1, a1@(AvailTC p1 _ []), mp1)
804 (name2, a2@(AvailTC p2 _ []), mp2)
805 = ASSERT( name1 == name2 && isNothing mp1 && isNothing mp2 )
806 if p1 == name1 then (name1, a1, Just p2)
807 else (name1, a2, Just p1)
808 combine x y = pprPanic "filterImports/combine" (ppr x $$ ppr y)
809
810 lookup_name :: RdrName -> IELookupM (Name, AvailInfo, Maybe Name)
811 lookup_name rdr | isQual rdr = failLookupWith (QualImportError rdr)
812 | Just succ <- mb_success = return succ
813 | otherwise = failLookupWith BadImport
814 where
815 mb_success = lookupOccEnv imp_occ_env (rdrNameOcc rdr)
816
817 lookup_lie :: LIE RdrName -> TcRn [(LIE Name, AvailInfo)]
818 lookup_lie (L loc ieRdr)
819 = do (stuff, warns) <- setSrcSpan loc $
820 liftM (fromMaybe ([],[])) $
821 run_lookup (lookup_ie ieRdr)
822 mapM_ emit_warning warns
823 return [ (L loc ie, avail) | (ie,avail) <- stuff ]
824 where
825 -- Warn when importing T(..) if T was exported abstractly
826 emit_warning (DodgyImport n) = whenWOptM Opt_WarnDodgyImports $
827 addWarn (Reason Opt_WarnDodgyImports) (dodgyImportWarn n)
828 emit_warning MissingImportList = whenWOptM Opt_WarnMissingImportList $
829 addWarn (Reason Opt_WarnMissingImportList) (missingImportListItem ieRdr)
830 emit_warning BadImportW = whenWOptM Opt_WarnDodgyImports $
831 addWarn (Reason Opt_WarnDodgyImports) (lookup_err_msg BadImport)
832
833 run_lookup :: IELookupM a -> TcRn (Maybe a)
834 run_lookup m = case m of
835 Failed err -> addErr (lookup_err_msg err) >> return Nothing
836 Succeeded a -> return (Just a)
837
838 lookup_err_msg err = case err of
839 BadImport -> badImportItemErr iface decl_spec ieRdr all_avails
840 IllegalImport -> illegalImportItemErr
841 QualImportError rdr -> qualImportItemErr rdr
842
843 -- For each import item, we convert its RdrNames to Names,
844 -- and at the same time construct an AvailInfo corresponding
845 -- to what is actually imported by this item.
846 -- Returns Nothing on error.
847 -- We return a list here, because in the case of an import
848 -- item like C, if we are hiding, then C refers to *both* a
849 -- type/class and a data constructor. Moreover, when we import
850 -- data constructors of an associated family, we need separate
851 -- AvailInfos for the data constructors and the family (as they have
852 -- different parents). See Note [Dealing with imports]
853 lookup_ie :: IE RdrName -> IELookupM ([(IE Name, AvailInfo)], [IELookupWarning])
854 lookup_ie ie = handle_bad_import $ do
855 case ie of
856 IEVar (L l n) -> do
857 (name, avail, _) <- lookup_name n
858 return ([(IEVar (L l name), trimAvail avail name)], [])
859
860 IEThingAll (L l tc) -> do
861 (name, avail, mb_parent) <- lookup_name tc
862 let warns = case avail of
863 Avail {} -- e.g. f(..)
864 -> [DodgyImport tc]
865
866 AvailTC _ subs fs
867 | null (drop 1 subs) && null fs -- e.g. T(..) where T is a synonym
868 -> [DodgyImport tc]
869
870 | not (is_qual decl_spec) -- e.g. import M( T(..) )
871 -> [MissingImportList]
872
873 | otherwise
874 -> []
875
876 renamed_ie = IEThingAll (L l name)
877 sub_avails = case avail of
878 Avail {} -> []
879 AvailTC name2 subs fs -> [(renamed_ie, AvailTC name2 (subs \\ [name]) fs)]
880 case mb_parent of
881 Nothing -> return ([(renamed_ie, avail)], warns)
882 -- non-associated ty/cls
883 Just parent -> return ((renamed_ie, AvailTC parent [name] []) : sub_avails, warns)
884 -- associated type
885
886 IEThingAbs (L l tc)
887 | want_hiding -- hiding ( C )
888 -- Here the 'C' can be a data constructor
889 -- *or* a type/class, or even both
890 -> let tc_name = lookup_name tc
891 dc_name = lookup_name (setRdrNameSpace tc srcDataName)
892 in
893 case catIELookupM [ tc_name, dc_name ] of
894 [] -> failLookupWith BadImport
895 names -> return ([mkIEThingAbs l name | name <- names], [])
896 | otherwise
897 -> do nameAvail <- lookup_name tc
898 return ([mkIEThingAbs l nameAvail], [])
899
900 IEThingWith (L l rdr_tc) wc rdr_ns rdr_fs ->
901 ASSERT2(null rdr_fs, ppr rdr_fs) do
902 (name, AvailTC _ ns subflds, mb_parent) <- lookup_name rdr_tc
903
904 -- Look up the children in the sub-names of the parent
905 let subnames = case ns of -- The tc is first in ns,
906 [] -> [] -- if it is there at all
907 -- See the AvailTC Invariant in Avail.hs
908 (n1:ns1) | n1 == name -> ns1
909 | otherwise -> ns
910 case lookupChildren (map Left subnames ++ map Right subflds) rdr_ns of
911 Nothing -> failLookupWith BadImport
912 Just (childnames, childflds) ->
913 case mb_parent of
914 -- non-associated ty/cls
915 Nothing
916 -> return ([(IEThingWith (L l name) wc childnames childflds,
917 AvailTC name (name:map unLoc childnames) (map unLoc childflds))],
918 [])
919 -- associated ty
920 Just parent
921 -> return ([(IEThingWith (L l name) wc childnames childflds,
922 AvailTC name (map unLoc childnames) (map unLoc childflds)),
923 (IEThingWith (L l name) wc childnames childflds,
924 AvailTC parent [name] [])],
925 [])
926
927 _other -> failLookupWith IllegalImport
928 -- could be IEModuleContents, IEGroup, IEDoc, IEDocNamed
929 -- all errors.
930
931 where
932 mkIEThingAbs l (n, av, Nothing ) = (IEThingAbs (L l n),
933 trimAvail av n)
934 mkIEThingAbs l (n, _, Just parent) = (IEThingAbs (L l n),
935 AvailTC parent [n] [])
936
937 handle_bad_import m = catchIELookup m $ \err -> case err of
938 BadImport | want_hiding -> return ([], [BadImportW])
939 _ -> failLookupWith err
940
941 type IELookupM = MaybeErr IELookupError
942
943 data IELookupWarning
944 = BadImportW
945 | MissingImportList
946 | DodgyImport RdrName
947 -- NB. use the RdrName for reporting a "dodgy" import
948
949 data IELookupError
950 = QualImportError RdrName
951 | BadImport
952 | IllegalImport
953
954 failLookupWith :: IELookupError -> IELookupM a
955 failLookupWith err = Failed err
956
957 catchIELookup :: IELookupM a -> (IELookupError -> IELookupM a) -> IELookupM a
958 catchIELookup m h = case m of
959 Succeeded r -> return r
960 Failed err -> h err
961
962 catIELookupM :: [IELookupM a] -> [a]
963 catIELookupM ms = [ a | Succeeded a <- ms ]
964
965 {-
966 ************************************************************************
967 * *
968 \subsection{Import/Export Utils}
969 * *
970 ************************************************************************
971 -}
972
973 plusAvail :: AvailInfo -> AvailInfo -> AvailInfo
974 plusAvail a1 a2
975 | debugIsOn && availName a1 /= availName a2
976 = pprPanic "RnEnv.plusAvail names differ" (hsep [ppr a1,ppr a2])
977 plusAvail a1@(Avail {}) (Avail {}) = a1
978 plusAvail (AvailTC _ [] []) a2@(AvailTC {}) = a2
979 plusAvail a1@(AvailTC {}) (AvailTC _ [] []) = a1
980 plusAvail (AvailTC n1 (s1:ss1) fs1) (AvailTC n2 (s2:ss2) fs2)
981 = case (n1==s1, n2==s2) of -- Maintain invariant the parent is first
982 (True,True) -> AvailTC n1 (s1 : (ss1 `unionLists` ss2))
983 (fs1 `unionLists` fs2)
984 (True,False) -> AvailTC n1 (s1 : (ss1 `unionLists` (s2:ss2)))
985 (fs1 `unionLists` fs2)
986 (False,True) -> AvailTC n1 (s2 : ((s1:ss1) `unionLists` ss2))
987 (fs1 `unionLists` fs2)
988 (False,False) -> AvailTC n1 ((s1:ss1) `unionLists` (s2:ss2))
989 (fs1 `unionLists` fs2)
990 plusAvail (AvailTC n1 ss1 fs1) (AvailTC _ [] fs2)
991 = AvailTC n1 ss1 (fs1 `unionLists` fs2)
992 plusAvail (AvailTC n1 [] fs1) (AvailTC _ ss2 fs2)
993 = AvailTC n1 ss2 (fs1 `unionLists` fs2)
994 plusAvail a1 a2 = pprPanic "RnEnv.plusAvail" (hsep [ppr a1,ppr a2])
995
996 -- | trims an 'AvailInfo' to keep only a single name
997 trimAvail :: AvailInfo -> Name -> AvailInfo
998 trimAvail (Avail b n) _ = Avail b n
999 trimAvail (AvailTC n ns fs) m = case find ((== m) . flSelector) fs of
1000 Just x -> AvailTC n [] [x]
1001 Nothing -> ASSERT( m `elem` ns ) AvailTC n [m] []
1002
1003 -- | filters 'AvailInfo's by the given predicate
1004 filterAvails :: (Name -> Bool) -> [AvailInfo] -> [AvailInfo]
1005 filterAvails keep avails = foldr (filterAvail keep) [] avails
1006
1007 -- | filters an 'AvailInfo' by the given predicate
1008 filterAvail :: (Name -> Bool) -> AvailInfo -> [AvailInfo] -> [AvailInfo]
1009 filterAvail keep ie rest =
1010 case ie of
1011 Avail _ n | keep n -> ie : rest
1012 | otherwise -> rest
1013 AvailTC tc ns fs ->
1014 let ns' = filter keep ns
1015 fs' = filter (keep . flSelector) fs in
1016 if null ns' && null fs' then rest else AvailTC tc ns' fs' : rest
1017
1018 -- | Given an import\/export spec, construct the appropriate 'GlobalRdrElt's.
1019 gresFromIE :: ImpDeclSpec -> (LIE Name, AvailInfo) -> [GlobalRdrElt]
1020 gresFromIE decl_spec (L loc ie, avail)
1021 = gresFromAvail prov_fn avail
1022 where
1023 is_explicit = case ie of
1024 IEThingAll (L _ name) -> \n -> n == name
1025 _ -> \_ -> True
1026 prov_fn name
1027 = Just (ImpSpec { is_decl = decl_spec, is_item = item_spec })
1028 where
1029 item_spec = ImpSome { is_explicit = is_explicit name, is_iloc = loc }
1030
1031
1032 {-
1033 Note [Children for duplicate record fields]
1034 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1035 Consider the module
1036
1037 {-# LANGUAGE DuplicateRecordFields #-}
1038 module M (F(foo, MkFInt, MkFBool)) where
1039 data family F a
1040 data instance F Int = MkFInt { foo :: Int }
1041 data instance F Bool = MkFBool { foo :: Bool }
1042
1043 The `foo` in the export list refers to *both* selectors! For this
1044 reason, lookupChildren builds an environment that maps the FastString
1045 to a list of items, rather than a single item.
1046 -}
1047
1048 mkChildEnv :: [GlobalRdrElt] -> NameEnv [GlobalRdrElt]
1049 mkChildEnv gres = foldr add emptyNameEnv gres
1050 where
1051 add gre env = case gre_par gre of
1052 FldParent p _ -> extendNameEnv_Acc (:) singleton env p gre
1053 ParentIs p -> extendNameEnv_Acc (:) singleton env p gre
1054 NoParent -> env
1055 PatternSynonym -> env
1056
1057 findPatSyns :: [GlobalRdrElt] -> [GlobalRdrElt]
1058 findPatSyns gres = foldr add [] gres
1059 where
1060 add g@(GRE { gre_par = PatternSynonym }) ps =
1061 g:ps
1062 add _ ps = ps
1063
1064 findChildren :: NameEnv [a] -> Name -> [a]
1065 findChildren env n = lookupNameEnv env n `orElse` []
1066
1067 lookupChildren :: [Either Name FieldLabel] -> [Located RdrName]
1068 -> Maybe ([Located Name], [Located FieldLabel])
1069 -- (lookupChildren all_kids rdr_items) maps each rdr_item to its
1070 -- corresponding Name all_kids, if the former exists
1071 -- The matching is done by FastString, not OccName, so that
1072 -- Cls( meth, AssocTy )
1073 -- will correctly find AssocTy among the all_kids of Cls, even though
1074 -- the RdrName for AssocTy may have a (bogus) DataName namespace
1075 -- (Really the rdr_items should be FastStrings in the first place.)
1076 lookupChildren all_kids rdr_items
1077 = do xs <- mapM doOne rdr_items
1078 return (fmap concat (partitionEithers xs))
1079 where
1080 doOne (L l r) = case (lookupFsEnv kid_env . occNameFS . rdrNameOcc) r of
1081 Just [Left n] -> Just (Left (L l n))
1082 Just rs | all isRight rs -> Just (Right (map (L l) (rights rs)))
1083 _ -> Nothing
1084
1085 -- See Note [Children for duplicate record fields]
1086 kid_env = extendFsEnvList_C (++) emptyFsEnv
1087 [(either (occNameFS . nameOccName) flLabel x, [x]) | x <- all_kids]
1088
1089
1090 classifyGREs :: [GlobalRdrElt] -> ([Name], [FieldLabel])
1091 classifyGREs = partitionEithers . map classifyGRE
1092
1093 classifyGRE :: GlobalRdrElt -> Either Name FieldLabel
1094 classifyGRE gre = case gre_par gre of
1095 FldParent _ Nothing -> Right (FieldLabel (occNameFS (nameOccName n)) False n)
1096 FldParent _ (Just lbl) -> Right (FieldLabel lbl True n)
1097 _ -> Left n
1098 where
1099 n = gre_name gre
1100
1101 -- | Combines 'AvailInfo's from the same family
1102 -- 'avails' may have several items with the same availName
1103 -- E.g import Ix( Ix(..), index )
1104 -- will give Ix(Ix,index,range) and Ix(index)
1105 -- We want to combine these; addAvail does that
1106 nubAvails :: [AvailInfo] -> [AvailInfo]
1107 nubAvails avails = nameEnvElts (foldl add emptyNameEnv avails)
1108 where
1109 add env avail = extendNameEnv_C plusAvail env (availName avail) avail
1110
1111 {-
1112 ************************************************************************
1113 * *
1114 \subsection{Export list processing}
1115 * *
1116 ************************************************************************
1117
1118 Processing the export list.
1119
1120 You might think that we should record things that appear in the export
1121 list as ``occurrences'' (using @addOccurrenceName@), but you'd be
1122 wrong. We do check (here) that they are in scope, but there is no
1123 need to slurp in their actual declaration (which is what
1124 @addOccurrenceName@ forces).
1125
1126 Indeed, doing so would big trouble when compiling @PrelBase@, because
1127 it re-exports @GHC@, which includes @takeMVar#@, whose type includes
1128 @ConcBase.StateAndSynchVar#@, and so on...
1129
1130 Note [Exports of data families]
1131 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1132 Suppose you see (Trac #5306)
1133 module M where
1134 import X( F )
1135 data instance F Int = FInt
1136 What does M export? AvailTC F [FInt]
1137 or AvailTC F [F,FInt]?
1138 The former is strictly right because F isn't defined in this module.
1139 But then you can never do an explicit import of M, thus
1140 import M( F( FInt ) )
1141 because F isn't exported by M. Nor can you import FInt alone from here
1142 import M( FInt )
1143 because we don't have syntax to support that. (It looks like an import of
1144 the type FInt.)
1145
1146 At one point I implemented a compromise:
1147 * When constructing exports with no export list, or with module M(
1148 module M ), we add the parent to the exports as well.
1149 * But not when you see module M( f ), even if f is a
1150 class method with a parent.
1151 * Nor when you see module M( module N ), with N /= M.
1152
1153 But the compromise seemed too much of a hack, so we backed it out.
1154 You just have to use an explicit export list:
1155 module M( F(..) ) where ...
1156 -}
1157
1158 type ExportAccum -- The type of the accumulating parameter of
1159 -- the main worker function in rnExports
1160 = ([LIE Name], -- Export items with Names
1161 ExportOccMap, -- Tracks exported occurrence names
1162 [AvailInfo]) -- The accumulated exported stuff
1163 -- Not nub'd!
1164
1165 emptyExportAccum :: ExportAccum
1166 emptyExportAccum = ([], emptyOccEnv, [])
1167
1168 type ExportOccMap = OccEnv (Name, IE RdrName)
1169 -- Tracks what a particular exported OccName
1170 -- in an export list refers to, and which item
1171 -- it came from. It's illegal to export two distinct things
1172 -- that have the same occurrence name
1173
1174 rnExports :: Bool -- False => no 'module M(..) where' header at all
1175 -> Maybe (Located [LIE RdrName]) -- Nothing => no explicit export list
1176 -> TcGblEnv
1177 -> RnM (Maybe [LIE Name], TcGblEnv)
1178
1179 -- Complains if two distinct exports have same OccName
1180 -- Warns about identical exports.
1181 -- Complains about exports items not in scope
1182
1183 rnExports explicit_mod exports
1184 tcg_env@(TcGblEnv { tcg_mod = this_mod,
1185 tcg_rdr_env = rdr_env,
1186 tcg_imports = imports })
1187 = unsetWOptM Opt_WarnWarningsDeprecations $
1188 -- Do not report deprecations arising from the export
1189 -- list, to avoid bleating about re-exporting a deprecated
1190 -- thing (especially via 'module Foo' export item)
1191 do {
1192 -- If the module header is omitted altogether, then behave
1193 -- as if the user had written "module Main(main) where..."
1194 -- EXCEPT in interactive mode, when we behave as if he had
1195 -- written "module Main where ..."
1196 -- Reason: don't want to complain about 'main' not in scope
1197 -- in interactive mode
1198 ; dflags <- getDynFlags
1199 ; let real_exports
1200 | explicit_mod = exports
1201 | ghcLink dflags == LinkInMemory = Nothing
1202 | otherwise
1203 = Just (noLoc [noLoc (IEVar (noLoc main_RDR_Unqual))])
1204 -- ToDo: the 'noLoc' here is unhelpful if 'main'
1205 -- turns out to be out of scope
1206
1207 ; (rn_exports, avails) <- exports_from_avail real_exports rdr_env imports this_mod
1208 ; traceRn (ppr avails)
1209 ; let final_avails = nubAvails avails -- Combine families
1210 final_ns = availsToNameSetWithSelectors final_avails
1211
1212 ; traceRn (text "rnExports: Exports:" <+> ppr final_avails)
1213
1214 ; let new_tcg_env =
1215 (tcg_env { tcg_exports = final_avails,
1216 tcg_rn_exports = case tcg_rn_exports tcg_env of
1217 Nothing -> Nothing
1218 Just _ -> rn_exports,
1219 tcg_dus = tcg_dus tcg_env `plusDU`
1220 usesOnly final_ns })
1221 ; return (rn_exports, new_tcg_env) }
1222
1223 exports_from_avail :: Maybe (Located [LIE RdrName])
1224 -- Nothing => no explicit export list
1225 -> GlobalRdrEnv
1226 -> ImportAvails
1227 -> Module
1228 -> RnM (Maybe [LIE Name], [AvailInfo])
1229
1230 exports_from_avail Nothing rdr_env _imports _this_mod
1231 -- The same as (module M) where M is the current module name,
1232 -- so that's how we handle it, except we also export the data family
1233 -- when a data instance is exported.
1234 = let avails = [ fix_faminst $ availFromGRE gre
1235 | gre <- globalRdrEnvElts rdr_env
1236 , isLocalGRE gre ]
1237 in return (Nothing, avails)
1238 where
1239 -- #11164: when we define a data instance
1240 -- but not data family, re-export the family
1241 -- Even though we don't check whether this is actually a data family
1242 -- only data families can locally define subordinate things (`ns` here)
1243 -- without locally defining (and instead importing) the parent (`n`)
1244 fix_faminst (AvailTC n ns flds)
1245 | not (n `elem` ns)
1246 = AvailTC n (n:ns) flds
1247
1248 fix_faminst avail = avail
1249
1250
1251 exports_from_avail (Just (L _ rdr_items)) rdr_env imports this_mod
1252 = do (ie_names, _, exports) <- foldlM do_litem emptyExportAccum rdr_items
1253 return (Just ie_names, exports)
1254 where
1255 do_litem :: ExportAccum -> LIE RdrName -> RnM ExportAccum
1256 do_litem acc lie = setSrcSpan (getLoc lie) (exports_from_item acc lie)
1257
1258 -- Maps a parent to its in-scope children
1259 kids_env :: NameEnv [GlobalRdrElt]
1260 kids_env = mkChildEnv (globalRdrEnvElts rdr_env)
1261
1262 pat_syns :: [GlobalRdrElt]
1263 pat_syns = findPatSyns (globalRdrEnvElts rdr_env)
1264
1265 imported_modules = [ imv_name imv
1266 | xs <- moduleEnvElts $ imp_mods imports, imv <- xs ]
1267
1268 exports_from_item :: ExportAccum -> LIE RdrName -> RnM ExportAccum
1269 exports_from_item acc@(ie_names, occs, exports)
1270 (L loc (IEModuleContents (L lm mod)))
1271 | let earlier_mods = [ mod
1272 | (L _ (IEModuleContents (L _ mod))) <- ie_names ]
1273 , mod `elem` earlier_mods -- Duplicate export of M
1274 = do { warn_dup_exports <- woptM Opt_WarnDuplicateExports ;
1275 warnIf (Reason Opt_WarnDuplicateExports) warn_dup_exports
1276 (dupModuleExport mod) ;
1277 return acc }
1278
1279 | otherwise
1280 = do { warnDodgyExports <- woptM Opt_WarnDodgyExports
1281 ; let { exportValid = (mod `elem` imported_modules)
1282 || (moduleName this_mod == mod)
1283 ; gre_prs = pickGREsModExp mod (globalRdrEnvElts rdr_env)
1284 ; new_exports = map (availFromGRE . fst) gre_prs
1285 ; names = map (gre_name . fst) gre_prs
1286 ; all_gres = foldr (\(gre1,gre2) gres -> gre1 : gre2 : gres) [] gre_prs
1287 }
1288
1289 ; checkErr exportValid (moduleNotImported mod)
1290 ; warnIf (Reason Opt_WarnDodgyExports)
1291 (warnDodgyExports && exportValid && null gre_prs)
1292 (nullModuleExport mod)
1293
1294 ; traceRn (text "efa" <+> (ppr mod $$ ppr all_gres))
1295 ; addUsedGREs all_gres
1296
1297 ; occs' <- check_occs (IEModuleContents (noLoc mod)) occs names
1298 -- This check_occs not only finds conflicts
1299 -- between this item and others, but also
1300 -- internally within this item. That is, if
1301 -- 'M.x' is in scope in several ways, we'll have
1302 -- several members of mod_avails with the same
1303 -- OccName.
1304 ; traceRn (vcat [ text "export mod" <+> ppr mod
1305 , ppr new_exports ])
1306 ; return (L loc (IEModuleContents (L lm mod)) : ie_names,
1307 occs', new_exports ++ exports) }
1308
1309 exports_from_item acc@(lie_names, occs, exports) (L loc ie)
1310 | isDoc ie
1311 = do new_ie <- lookup_doc_ie ie
1312 return (L loc new_ie : lie_names, occs, exports)
1313
1314 | otherwise
1315 = do (new_ie, avail) <- lookup_ie ie
1316 if isUnboundName (ieName new_ie)
1317 then return acc -- Avoid error cascade
1318 else do
1319
1320 occs' <- check_occs ie occs (availNames avail)
1321
1322 return (L loc new_ie : lie_names, occs', avail : exports)
1323
1324 -------------
1325 lookup_ie :: IE RdrName -> RnM (IE Name, AvailInfo)
1326 lookup_ie (IEVar (L l rdr))
1327 = do (name, avail) <- lookupGreAvailRn rdr
1328 return (IEVar (L l name), avail)
1329
1330 lookup_ie (IEThingAbs (L l rdr))
1331 = do (name, avail) <- lookupGreAvailRn rdr
1332 return (IEThingAbs (L l name), avail)
1333
1334 lookup_ie ie@(IEThingAll n)
1335 = do
1336 (n, avail, flds) <- lookup_ie_all ie n
1337 let name = unLoc n
1338 return (IEThingAll n, AvailTC name (name:avail) flds)
1339
1340
1341 lookup_ie ie@(IEThingWith l wc sub_rdrs _)
1342 = do
1343 (lname, subs, avails, flds) <- lookup_ie_with ie l sub_rdrs
1344 (_, all_avail, all_flds) <-
1345 case wc of
1346 NoIEWildcard -> return (lname, [], [])
1347 IEWildcard _ -> lookup_ie_all ie l
1348 let name = unLoc lname
1349 return (IEThingWith lname wc subs [],
1350 AvailTC name (name : avails ++ all_avail)
1351 (flds ++ all_flds))
1352
1353
1354
1355
1356 lookup_ie _ = panic "lookup_ie" -- Other cases covered earlier
1357
1358 lookup_ie_with :: IE RdrName -> Located RdrName -> [Located RdrName]
1359 -> RnM (Located Name, [Located Name], [Name], [FieldLabel])
1360 lookup_ie_with ie (L l rdr) sub_rdrs
1361 = do name <- lookupGlobalOccRnExport rdr
1362 let gres = findChildren kids_env name
1363 mchildren =
1364 lookupChildren (map classifyGRE (gres ++ pat_syns)) sub_rdrs
1365 addUsedKids rdr gres
1366 if isUnboundName name
1367 then return (L l name, [], [name], [])
1368 else
1369 case mchildren of
1370 Nothing -> do
1371 addErr (exportItemErr ie)
1372 return (L l name, [], [name], [])
1373 Just (non_flds, flds) -> do
1374 addUsedKids rdr gres
1375 return (L l name, non_flds
1376 , map unLoc non_flds
1377 , map unLoc flds)
1378 lookup_ie_all :: IE RdrName -> Located RdrName
1379 -> RnM (Located Name, [Name], [FieldLabel])
1380 lookup_ie_all ie (L l rdr) =
1381 do name <- lookupGlobalOccRnExport rdr
1382 let gres = findChildren kids_env name
1383 (non_flds, flds) = classifyGREs gres
1384 addUsedKids rdr gres
1385 warnDodgyExports <- woptM Opt_WarnDodgyExports
1386 when (null gres) $
1387 if isTyConName name
1388 then when warnDodgyExports $
1389 addWarn (Reason Opt_WarnDodgyExports)
1390 (dodgyExportWarn name)
1391 else -- This occurs when you export T(..), but
1392 -- only import T abstractly, or T is a synonym.
1393 addErr (exportItemErr ie)
1394 return (L l name, non_flds, flds)
1395
1396 -------------
1397 lookup_doc_ie :: IE RdrName -> RnM (IE Name)
1398 lookup_doc_ie (IEGroup lev doc) = do rn_doc <- rnHsDoc doc
1399 return (IEGroup lev rn_doc)
1400 lookup_doc_ie (IEDoc doc) = do rn_doc <- rnHsDoc doc
1401 return (IEDoc rn_doc)
1402 lookup_doc_ie (IEDocNamed str) = return (IEDocNamed str)
1403 lookup_doc_ie _ = panic "lookup_doc_ie" -- Other cases covered earlier
1404
1405 -- In an export item M.T(A,B,C), we want to treat the uses of
1406 -- A,B,C as if they were M.A, M.B, M.C
1407 -- Happily pickGREs does just the right thing
1408 addUsedKids :: RdrName -> [GlobalRdrElt] -> RnM ()
1409 addUsedKids parent_rdr kid_gres = addUsedGREs (pickGREs parent_rdr kid_gres)
1410
1411 isDoc :: IE RdrName -> Bool
1412 isDoc (IEDoc _) = True
1413 isDoc (IEDocNamed _) = True
1414 isDoc (IEGroup _ _) = True
1415 isDoc _ = False
1416
1417
1418 -------------------------------
1419 check_occs :: IE RdrName -> ExportOccMap -> [Name] -> RnM ExportOccMap
1420 check_occs ie occs names -- 'names' are the entities specifed by 'ie'
1421 = foldlM check occs names
1422 where
1423 check occs name
1424 = case lookupOccEnv occs name_occ of
1425 Nothing -> return (extendOccEnv occs name_occ (name, ie))
1426
1427 Just (name', ie')
1428 | name == name' -- Duplicate export
1429 -- But we don't want to warn if the same thing is exported
1430 -- by two different module exports. See ticket #4478.
1431 -> do unless (dupExport_ok name ie ie') $ do
1432 warn_dup_exports <- woptM Opt_WarnDuplicateExports
1433 warnIf (Reason Opt_WarnDuplicateExports) warn_dup_exports
1434 (dupExportWarn name_occ ie ie')
1435 return occs
1436
1437 | otherwise -- Same occ name but different names: an error
1438 -> do { global_env <- getGlobalRdrEnv ;
1439 addErr (exportClashErr global_env name' name ie' ie) ;
1440 return occs }
1441 where
1442 name_occ = nameOccName name
1443
1444
1445 dupExport_ok :: Name -> IE RdrName -> IE RdrName -> Bool
1446 -- The Name is exported by both IEs. Is that ok?
1447 -- "No" iff the name is mentioned explicitly in both IEs
1448 -- or one of the IEs mentions the name *alone*
1449 -- "Yes" otherwise
1450 --
1451 -- Examples of "no": module M( f, f )
1452 -- module M( fmap, Functor(..) )
1453 -- module M( module Data.List, head )
1454 --
1455 -- Example of "yes"
1456 -- module M( module A, module B ) where
1457 -- import A( f )
1458 -- import B( f )
1459 --
1460 -- Example of "yes" (Trac #2436)
1461 -- module M( C(..), T(..) ) where
1462 -- class C a where { data T a }
1463 -- instace C Int where { data T Int = TInt }
1464 --
1465 -- Example of "yes" (Trac #2436)
1466 -- module Foo ( T ) where
1467 -- data family T a
1468 -- module Bar ( T(..), module Foo ) where
1469 -- import Foo
1470 -- data instance T Int = TInt
1471
1472 dupExport_ok n ie1 ie2
1473 = not ( single ie1 || single ie2
1474 || (explicit_in ie1 && explicit_in ie2) )
1475 where
1476 explicit_in (IEModuleContents _) = False -- module M
1477 explicit_in (IEThingAll r) = nameOccName n == rdrNameOcc (unLoc r) -- T(..)
1478 explicit_in _ = True
1479
1480 single (IEVar {}) = True
1481 single (IEThingAbs {}) = True
1482 single _ = False
1483
1484 {-
1485 *********************************************************
1486 * *
1487 \subsection{Unused names}
1488 * *
1489 *********************************************************
1490 -}
1491
1492 reportUnusedNames :: Maybe (Located [LIE RdrName]) -- Export list
1493 -> TcGblEnv -> RnM ()
1494 reportUnusedNames _export_decls gbl_env
1495 = do { traceRn ((text "RUN") <+> (ppr (tcg_dus gbl_env)))
1496 ; warnUnusedImportDecls gbl_env
1497 ; warnUnusedTopBinds unused_locals
1498 ; warnMissingSignatures gbl_env }
1499 where
1500 used_names :: NameSet
1501 used_names = findUses (tcg_dus gbl_env) emptyNameSet
1502 -- NB: currently, if f x = g, we only treat 'g' as used if 'f' is used
1503 -- Hence findUses
1504
1505 -- Collect the defined names from the in-scope environment
1506 defined_names :: [GlobalRdrElt]
1507 defined_names = globalRdrEnvElts (tcg_rdr_env gbl_env)
1508
1509 -- Note that defined_and_used, defined_but_not_used
1510 -- are both [GRE]; that's why we need defined_and_used
1511 -- rather than just used_names
1512 _defined_and_used, defined_but_not_used :: [GlobalRdrElt]
1513 (_defined_and_used, defined_but_not_used)
1514 = partition (gre_is_used used_names) defined_names
1515
1516 kids_env = mkChildEnv defined_names
1517 -- This is done in mkExports too; duplicated work
1518
1519 gre_is_used :: NameSet -> GlobalRdrElt -> Bool
1520 gre_is_used used_names (GRE {gre_name = name})
1521 = name `elemNameSet` used_names
1522 || any (\ gre -> gre_name gre `elemNameSet` used_names) (findChildren kids_env name)
1523 -- A use of C implies a use of T,
1524 -- if C was brought into scope by T(..) or T(C)
1525
1526 -- Filter out the ones that are
1527 -- (a) defined in this module, and
1528 -- (b) not defined by a 'deriving' clause
1529 -- The latter have an Internal Name, so we can filter them out easily
1530 unused_locals :: [GlobalRdrElt]
1531 unused_locals = filter is_unused_local defined_but_not_used
1532 is_unused_local :: GlobalRdrElt -> Bool
1533 is_unused_local gre = isLocalGRE gre && isExternalName (gre_name gre)
1534
1535 {-
1536 *********************************************************
1537 * *
1538 \subsection{Unused imports}
1539 * *
1540 *********************************************************
1541
1542 This code finds which import declarations are unused. The
1543 specification and implementation notes are here:
1544 http://ghc.haskell.org/trac/ghc/wiki/Commentary/Compiler/UnusedImports
1545 -}
1546
1547 type ImportDeclUsage
1548 = ( LImportDecl Name -- The import declaration
1549 , [AvailInfo] -- What *is* used (normalised)
1550 , [Name] ) -- What is imported but *not* used
1551
1552 warnUnusedImportDecls :: TcGblEnv -> RnM ()
1553 warnUnusedImportDecls gbl_env
1554 = do { uses <- readMutVar (tcg_used_gres gbl_env)
1555 ; let user_imports = filterOut (ideclImplicit . unLoc) (tcg_rn_imports gbl_env)
1556 -- This whole function deals only with *user* imports
1557 -- both for warning about unnecessary ones, and for
1558 -- deciding the minimal ones
1559 rdr_env = tcg_rdr_env gbl_env
1560 fld_env = mkFieldEnv rdr_env
1561
1562 ; let usage :: [ImportDeclUsage]
1563 usage = findImportUsage user_imports uses
1564
1565 ; traceRn (vcat [ text "Uses:" <+> ppr uses
1566 , text "Import usage" <+> ppr usage])
1567 ; whenWOptM Opt_WarnUnusedImports $
1568 mapM_ (warnUnusedImport Opt_WarnUnusedImports fld_env) usage
1569
1570 ; whenGOptM Opt_D_dump_minimal_imports $
1571 printMinimalImports usage }
1572
1573 -- | Warn the user about top level binders that lack type signatures.
1574 warnMissingSignatures :: TcGblEnv -> RnM ()
1575 warnMissingSignatures gbl_env
1576 = do { let exports = availsToNameSet (tcg_exports gbl_env)
1577 sig_ns = tcg_sigs gbl_env
1578 -- We use sig_ns to exclude top-level bindings that are generated by GHC
1579 binds = collectHsBindsBinders $ tcg_binds gbl_env
1580 pat_syns = tcg_patsyns gbl_env
1581
1582 -- Warn about missing signatures
1583 -- Do this only when we we have a type to offer
1584 ; warn_missing_sigs <- woptM Opt_WarnMissingSignatures
1585 ; warn_only_exported <- woptM Opt_WarnMissingExportedSignatures
1586 ; warn_pat_syns <- woptM Opt_WarnMissingPatternSynonymSignatures
1587
1588 ; let add_sig_warns
1589 | warn_only_exported = add_warns Opt_WarnMissingExportedSignatures
1590 | warn_missing_sigs = add_warns Opt_WarnMissingSignatures
1591 | warn_pat_syns = add_warns Opt_WarnMissingPatternSynonymSignatures
1592 | otherwise = return ()
1593
1594 add_warns flag
1595 = when warn_pat_syns
1596 (mapM_ add_pat_syn_warn pat_syns) >>
1597 when (warn_missing_sigs || warn_only_exported)
1598 (mapM_ add_bind_warn binds)
1599 where
1600 add_pat_syn_warn p
1601 = add_warn (patSynName p) (pprPatSynType p)
1602
1603 add_bind_warn id
1604 = do { env <- tcInitTidyEnv -- Why not use emptyTidyEnv?
1605 ; let name = idName id
1606 (_, ty) = tidyOpenType env (idType id)
1607 ty_msg = ppr ty
1608 ; add_warn name ty_msg }
1609
1610 add_warn name ty_msg
1611 = when (name `elemNameSet` sig_ns && export_check name)
1612 (addWarnAt (Reason flag) (getSrcSpan name)
1613 (get_msg name ty_msg))
1614
1615 export_check name
1616 = not warn_only_exported || name `elemNameSet` exports
1617
1618 get_msg name ty_msg
1619 = sep [ text "Top-level binding with no type signature:",
1620 nest 2 $ pprPrefixName name <+> dcolon <+> ty_msg ]
1621
1622 ; add_sig_warns }
1623
1624 {-
1625 Note [The ImportMap]
1626 ~~~~~~~~~~~~~~~~~~~~
1627 The ImportMap is a short-lived intermediate data struture records, for
1628 each import declaration, what stuff brought into scope by that
1629 declaration is actually used in the module.
1630
1631 The SrcLoc is the location of the END of a particular 'import'
1632 declaration. Why *END*? Because we don't want to get confused
1633 by the implicit Prelude import. Consider (Trac #7476) the module
1634 import Foo( foo )
1635 main = print foo
1636 There is an implicit 'import Prelude(print)', and it gets a SrcSpan
1637 of line 1:1 (just the point, not a span). If we use the *START* of
1638 the SrcSpan to identify the import decl, we'll confuse the implicit
1639 import Prelude with the explicit 'import Foo'. So we use the END.
1640 It's just a cheap hack; we could equally well use the Span too.
1641
1642 The AvailInfos are the things imported from that decl (just a list,
1643 not normalised).
1644 -}
1645
1646 type ImportMap = Map SrcLoc [AvailInfo] -- See [The ImportMap]
1647
1648 findImportUsage :: [LImportDecl Name]
1649 -> [GlobalRdrElt]
1650 -> [ImportDeclUsage]
1651
1652 findImportUsage imports used_gres
1653 = map unused_decl imports
1654 where
1655 import_usage :: ImportMap
1656 import_usage
1657 = foldr extendImportMap Map.empty used_gres
1658
1659 unused_decl decl@(L loc (ImportDecl { ideclHiding = imps }))
1660 = (decl, nubAvails used_avails, nameSetElems unused_imps)
1661 where
1662 used_avails = Map.lookup (srcSpanEnd loc) import_usage `orElse` []
1663 -- srcSpanEnd: see Note [The ImportMap]
1664 used_names = availsToNameSetWithSelectors used_avails
1665 used_parents = mkNameSet [n | AvailTC n _ _ <- used_avails]
1666
1667 unused_imps -- Not trivial; see eg Trac #7454
1668 = case imps of
1669 Just (False, L _ imp_ies) ->
1670 foldr (add_unused . unLoc) emptyNameSet imp_ies
1671 _other -> emptyNameSet -- No explicit import list => no unused-name list
1672
1673 add_unused :: IE Name -> NameSet -> NameSet
1674 add_unused (IEVar (L _ n)) acc = add_unused_name n acc
1675 add_unused (IEThingAbs (L _ n)) acc = add_unused_name n acc
1676 add_unused (IEThingAll (L _ n)) acc = add_unused_all n acc
1677 add_unused (IEThingWith (L _ p) wc ns fs) acc =
1678 add_wc_all (add_unused_with p xs acc)
1679 where xs = map unLoc ns ++ map (flSelector . unLoc) fs
1680 add_wc_all = case wc of
1681 NoIEWildcard -> id
1682 IEWildcard _ -> add_unused_all p
1683 add_unused _ acc = acc
1684
1685 add_unused_name n acc
1686 | n `elemNameSet` used_names = acc
1687 | otherwise = acc `extendNameSet` n
1688 add_unused_all n acc
1689 | n `elemNameSet` used_names = acc
1690 | n `elemNameSet` used_parents = acc
1691 | otherwise = acc `extendNameSet` n
1692 add_unused_with p ns acc
1693 | all (`elemNameSet` acc1) ns = add_unused_name p acc1
1694 | otherwise = acc1
1695 where
1696 acc1 = foldr add_unused_name acc ns
1697 -- If you use 'signum' from Num, then the user may well have
1698 -- imported Num(signum). We don't want to complain that
1699 -- Num is not itself mentioned. Hence the two cases in add_unused_with.
1700
1701 extendImportMap :: GlobalRdrElt -> ImportMap -> ImportMap
1702 -- For each of a list of used GREs, find all the import decls that brought
1703 -- it into scope; choose one of them (bestImport), and record
1704 -- the RdrName in that import decl's entry in the ImportMap
1705 extendImportMap gre imp_map
1706 = add_imp gre (bestImport (gre_imp gre)) imp_map
1707 where
1708 add_imp :: GlobalRdrElt -> ImportSpec -> ImportMap -> ImportMap
1709 add_imp gre (ImpSpec { is_decl = imp_decl_spec }) imp_map
1710 = Map.insertWith add decl_loc [avail] imp_map
1711 where
1712 add _ avails = avail : avails -- add is really just a specialised (++)
1713 decl_loc = srcSpanEnd (is_dloc imp_decl_spec)
1714 -- For srcSpanEnd see Note [The ImportMap]
1715 avail = availFromGRE gre
1716
1717 warnUnusedImport :: WarningFlag -> NameEnv (FieldLabelString, Name)
1718 -> ImportDeclUsage -> RnM ()
1719 warnUnusedImport flag fld_env (L loc decl, used, unused)
1720 | Just (False,L _ []) <- ideclHiding decl
1721 = return () -- Do not warn for 'import M()'
1722
1723 | Just (True, L _ hides) <- ideclHiding decl
1724 , not (null hides)
1725 , pRELUDE_NAME == unLoc (ideclName decl)
1726 = return () -- Note [Do not warn about Prelude hiding]
1727 | null used = addWarnAt (Reason flag) loc msg1 -- Nothing used; drop entire decl
1728 | null unused = return () -- Everything imported is used; nop
1729 | otherwise = addWarnAt (Reason flag) loc msg2 -- Some imports are unused
1730 where
1731 msg1 = vcat [pp_herald <+> quotes pp_mod <+> pp_not_used,
1732 nest 2 (text "except perhaps to import instances from"
1733 <+> quotes pp_mod),
1734 text "To import instances alone, use:"
1735 <+> text "import" <+> pp_mod <> parens Outputable.empty ]
1736 msg2 = sep [pp_herald <+> quotes sort_unused,
1737 text "from module" <+> quotes pp_mod <+> pp_not_used]
1738 pp_herald = text "The" <+> pp_qual <+> text "import of"
1739 pp_qual
1740 | ideclQualified decl = text "qualified"
1741 | otherwise = Outputable.empty
1742 pp_mod = ppr (unLoc (ideclName decl))
1743 pp_not_used = text "is redundant"
1744
1745 ppr_possible_field n = case lookupNameEnv fld_env n of
1746 Just (fld, p) -> ppr p <> parens (ppr fld)
1747 Nothing -> ppr n
1748
1749 -- Print unused names in a deterministic (lexicographic) order
1750 sort_unused = pprWithCommas ppr_possible_field $
1751 sortBy (comparing nameOccName) unused
1752
1753 {-
1754 Note [Do not warn about Prelude hiding]
1755 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1756 We do not warn about
1757 import Prelude hiding( x, y )
1758 because even if nothing else from Prelude is used, it may be essential to hide
1759 x,y to avoid name-shadowing warnings. Example (Trac #9061)
1760 import Prelude hiding( log )
1761 f x = log where log = ()
1762
1763
1764
1765 Note [Printing minimal imports]
1766 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1767 To print the minimal imports we walk over the user-supplied import
1768 decls, and simply trim their import lists. NB that
1769
1770 * We do *not* change the 'qualified' or 'as' parts!
1771
1772 * We do not disard a decl altogether; we might need instances
1773 from it. Instead we just trim to an empty import list
1774 -}
1775
1776 printMinimalImports :: [ImportDeclUsage] -> RnM ()
1777 -- See Note [Printing minimal imports]
1778 printMinimalImports imports_w_usage
1779 = do { imports' <- mapM mk_minimal imports_w_usage
1780 ; this_mod <- getModule
1781 ; dflags <- getDynFlags
1782 ; liftIO $
1783 do { h <- openFile (mkFilename dflags this_mod) WriteMode
1784 ; printForUser dflags h neverQualify (vcat (map ppr imports')) }
1785 -- The neverQualify is important. We are printing Names
1786 -- but they are in the context of an 'import' decl, and
1787 -- we never qualify things inside there
1788 -- E.g. import Blag( f, b )
1789 -- not import Blag( Blag.f, Blag.g )!
1790 }
1791 where
1792 mkFilename dflags this_mod
1793 | Just d <- dumpDir dflags = d </> basefn
1794 | otherwise = basefn
1795 where
1796 basefn = moduleNameString (moduleName this_mod) ++ ".imports"
1797
1798 mk_minimal (L l decl, used, unused)
1799 | null unused
1800 , Just (False, _) <- ideclHiding decl
1801 = return (L l decl)
1802 | otherwise
1803 = do { let ImportDecl { ideclName = L _ mod_name
1804 , ideclSource = is_boot
1805 , ideclPkgQual = mb_pkg } = decl
1806 ; iface <- loadSrcInterface doc mod_name is_boot (fmap sl_fs mb_pkg)
1807 ; let lies = map (L l) (concatMap (to_ie iface) used)
1808 ; return (L l (decl { ideclHiding = Just (False, L l lies) })) }
1809 where
1810 doc = text "Compute minimal imports for" <+> ppr decl
1811
1812 to_ie :: ModIface -> AvailInfo -> [IE Name]
1813 -- The main trick here is that if we're importing all the constructors
1814 -- we want to say "T(..)", but if we're importing only a subset we want
1815 -- to say "T(A,B,C)". So we have to find out what the module exports.
1816 to_ie _ (Avail _ n)
1817 = [IEVar (noLoc n)]
1818 to_ie _ (AvailTC n [m] [])
1819 | n==m = [IEThingAbs (noLoc n)]
1820 to_ie iface (AvailTC n ns fs)
1821 = case [(xs,gs) | AvailTC x xs gs <- mi_exports iface
1822 , x == n
1823 , x `elem` xs -- Note [Partial export]
1824 ] of
1825 [xs] | all_used xs -> [IEThingAll (noLoc n)]
1826 | otherwise -> [IEThingWith (noLoc n) NoIEWildcard
1827 (map noLoc (filter (/= n) ns))
1828 (map noLoc fs)]
1829 -- Note [Overloaded field import]
1830 _other | all_non_overloaded fs
1831 -> map (IEVar . noLoc) $ ns ++ map flSelector fs
1832 | otherwise -> [IEThingWith (noLoc n) NoIEWildcard
1833 (map noLoc (filter (/= n) ns)) (map noLoc fs)]
1834 where
1835 fld_lbls = map flLabel fs
1836
1837 all_used (avail_occs, avail_flds)
1838 = all (`elem` ns) avail_occs
1839 && all (`elem` fld_lbls) (map flLabel avail_flds)
1840
1841 all_non_overloaded = all (not . flIsOverloaded)
1842
1843 {-
1844 Note [Partial export]
1845 ~~~~~~~~~~~~~~~~~~~~~
1846 Suppose we have
1847
1848 module A( op ) where
1849 class C a where
1850 op :: a -> a
1851
1852 module B where
1853 import A
1854 f = ..op...
1855
1856 Then the minimal import for module B is
1857 import A( op )
1858 not
1859 import A( C( op ) )
1860 which we would usually generate if C was exported from B. Hence
1861 the (x `elem` xs) test when deciding what to generate.
1862
1863
1864 Note [Overloaded field import]
1865 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1866 On the other hand, if we have
1867
1868 {-# LANGUAGE DuplicateRecordFields #-}
1869 module A where
1870 data T = MkT { foo :: Int }
1871
1872 module B where
1873 import A
1874 f = ...foo...
1875
1876 then the minimal import for module B must be
1877 import A ( T(foo) )
1878 because when DuplicateRecordFields is enabled, field selectors are
1879 not in scope without their enclosing datatype.
1880
1881
1882 ************************************************************************
1883 * *
1884 \subsection{Errors}
1885 * *
1886 ************************************************************************
1887 -}
1888
1889 qualImportItemErr :: RdrName -> SDoc
1890 qualImportItemErr rdr
1891 = hang (text "Illegal qualified name in import item:")
1892 2 (ppr rdr)
1893
1894 badImportItemErrStd :: ModIface -> ImpDeclSpec -> IE RdrName -> SDoc
1895 badImportItemErrStd iface decl_spec ie
1896 = sep [text "Module", quotes (ppr (is_mod decl_spec)), source_import,
1897 text "does not export", quotes (ppr ie)]
1898 where
1899 source_import | mi_boot iface = text "(hi-boot interface)"
1900 | otherwise = Outputable.empty
1901
1902 badImportItemErrDataCon :: OccName -> ModIface -> ImpDeclSpec -> IE RdrName -> SDoc
1903 badImportItemErrDataCon dataType_occ iface decl_spec ie
1904 = vcat [ text "In module"
1905 <+> quotes (ppr (is_mod decl_spec))
1906 <+> source_import <> colon
1907 , nest 2 $ quotes datacon
1908 <+> text "is a data constructor of"
1909 <+> quotes dataType
1910 , text "To import it use"
1911 , nest 2 $ quotes (text "import")
1912 <+> ppr (is_mod decl_spec)
1913 <> parens_sp (dataType <> parens_sp datacon)
1914 , text "or"
1915 , nest 2 $ quotes (text "import")
1916 <+> ppr (is_mod decl_spec)
1917 <> parens_sp (dataType <> text "(..)")
1918 ]
1919 where
1920 datacon_occ = rdrNameOcc $ ieName ie
1921 datacon = parenSymOcc datacon_occ (ppr datacon_occ)
1922 dataType = parenSymOcc dataType_occ (ppr dataType_occ)
1923 source_import | mi_boot iface = text "(hi-boot interface)"
1924 | otherwise = Outputable.empty
1925 parens_sp d = parens (space <> d <> space) -- T( f,g )
1926
1927 badImportItemErr :: ModIface -> ImpDeclSpec -> IE RdrName -> [AvailInfo] -> SDoc
1928 badImportItemErr iface decl_spec ie avails
1929 = case find checkIfDataCon avails of
1930 Just con -> badImportItemErrDataCon (availOccName con) iface decl_spec ie
1931 Nothing -> badImportItemErrStd iface decl_spec ie
1932 where
1933 checkIfDataCon (AvailTC _ ns _) =
1934 case find (\n -> importedFS == nameOccNameFS n) ns of
1935 Just n -> isDataConName n
1936 Nothing -> False
1937 checkIfDataCon _ = False
1938 availOccName = nameOccName . availName
1939 nameOccNameFS = occNameFS . nameOccName
1940 importedFS = occNameFS . rdrNameOcc $ ieName ie
1941
1942 illegalImportItemErr :: SDoc
1943 illegalImportItemErr = text "Illegal import item"
1944
1945 dodgyImportWarn :: RdrName -> SDoc
1946 dodgyImportWarn item = dodgyMsg (text "import") item
1947 dodgyExportWarn :: Name -> SDoc
1948 dodgyExportWarn item = dodgyMsg (text "export") item
1949
1950 dodgyMsg :: (OutputableBndr n, HasOccName n) => SDoc -> n -> SDoc
1951 dodgyMsg kind tc
1952 = sep [ text "The" <+> kind <+> ptext (sLit "item")
1953 <+> quotes (ppr (IEThingAll (noLoc tc)))
1954 <+> text "suggests that",
1955 quotes (ppr tc) <+> text "has (in-scope) constructors or class methods,",
1956 text "but it has none" ]
1957
1958 exportItemErr :: IE RdrName -> SDoc
1959 exportItemErr export_item
1960 = sep [ text "The export item" <+> quotes (ppr export_item),
1961 text "attempts to export constructors or class methods that are not visible here" ]
1962
1963 exportClashErr :: GlobalRdrEnv -> Name -> Name -> IE RdrName -> IE RdrName
1964 -> MsgDoc
1965 exportClashErr global_env name1 name2 ie1 ie2
1966 = vcat [ text "Conflicting exports for" <+> quotes (ppr occ) <> colon
1967 , ppr_export ie1' name1'
1968 , ppr_export ie2' name2' ]
1969 where
1970 occ = nameOccName name1
1971 ppr_export ie name = nest 3 (hang (quotes (ppr ie) <+> text "exports" <+>
1972 quotes (ppr name))
1973 2 (pprNameProvenance (get_gre name)))
1974
1975 -- get_gre finds a GRE for the Name, so that we can show its provenance
1976 get_gre name
1977 = case lookupGRE_Name global_env name of
1978 (gre:_) -> gre
1979 [] -> pprPanic "exportClashErr" (ppr name)
1980 get_loc name = greSrcSpan (get_gre name)
1981 (name1', ie1', name2', ie2') = if get_loc name1 < get_loc name2
1982 then (name1, ie1, name2, ie2)
1983 else (name2, ie2, name1, ie1)
1984
1985 addDupDeclErr :: [GlobalRdrElt] -> TcRn ()
1986 addDupDeclErr [] = panic "addDupDeclErr: empty list"
1987 addDupDeclErr gres@(gre : _)
1988 = addErrAt (getSrcSpan (last sorted_names)) $
1989 -- Report the error at the later location
1990 vcat [text "Multiple declarations of" <+>
1991 quotes (ppr (nameOccName name)),
1992 -- NB. print the OccName, not the Name, because the
1993 -- latter might not be in scope in the RdrEnv and so will
1994 -- be printed qualified.
1995 text "Declared at:" <+>
1996 vcat (map (ppr . nameSrcLoc) sorted_names)]
1997 where
1998 name = gre_name gre
1999 sorted_names = sortWith nameSrcLoc (map gre_name gres)
2000
2001 dupExportWarn :: OccName -> IE RdrName -> IE RdrName -> SDoc
2002 dupExportWarn occ_name ie1 ie2
2003 = hsep [quotes (ppr occ_name),
2004 text "is exported by", quotes (ppr ie1),
2005 text "and", quotes (ppr ie2)]
2006
2007 dupModuleExport :: ModuleName -> SDoc
2008 dupModuleExport mod
2009 = hsep [text "Duplicate",
2010 quotes (text "Module" <+> ppr mod),
2011 text "in export list"]
2012
2013 moduleNotImported :: ModuleName -> SDoc
2014 moduleNotImported mod
2015 = text "The export item `module" <+> ppr mod <>
2016 text "' is not imported"
2017
2018 nullModuleExport :: ModuleName -> SDoc
2019 nullModuleExport mod
2020 = text "The export item `module" <+> ppr mod <> ptext (sLit "' exports nothing")
2021
2022 missingImportListWarn :: ModuleName -> SDoc
2023 missingImportListWarn mod
2024 = text "The module" <+> quotes (ppr mod) <+> ptext (sLit "does not have an explicit import list")
2025
2026 missingImportListItem :: IE RdrName -> SDoc
2027 missingImportListItem ie
2028 = text "The import item" <+> quotes (ppr ie) <+> ptext (sLit "does not have an explicit import list")
2029
2030 moduleWarn :: ModuleName -> WarningTxt -> SDoc
2031 moduleWarn mod (WarningTxt _ txt)
2032 = sep [ text "Module" <+> quotes (ppr mod) <> ptext (sLit ":"),
2033 nest 2 (vcat (map (ppr . sl_fs . unLoc) txt)) ]
2034 moduleWarn mod (DeprecatedTxt _ txt)
2035 = sep [ text "Module" <+> quotes (ppr mod)
2036 <+> text "is deprecated:",
2037 nest 2 (vcat (map (ppr . sl_fs . unLoc) txt)) ]
2038
2039 packageImportErr :: SDoc
2040 packageImportErr
2041 = text "Package-qualified imports are not enabled; use PackageImports"
2042
2043 -- This data decl will parse OK
2044 -- data T = a Int
2045 -- treating "a" as the constructor.
2046 -- It is really hard to make the parser spot this malformation.
2047 -- So the renamer has to check that the constructor is legal
2048 --
2049 -- We can get an operator as the constructor, even in the prefix form:
2050 -- data T = :% Int Int
2051 -- from interface files, which always print in prefix form
2052
2053 checkConName :: RdrName -> TcRn ()
2054 checkConName name = checkErr (isRdrDataCon name) (badDataCon name)
2055
2056 badDataCon :: RdrName -> SDoc
2057 badDataCon name
2058 = hsep [text "Illegal data constructor name", quotes (ppr name)]