SCC analysis for instances as well as types/classes
[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 Note [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_fords = foreign_decls })
548 = do { -- Process all type/class decls *except* family instances
549 ; let inst_decls = tycl_decls >>= group_instds
550 ; overload_ok <- xoptM LangExt.DuplicateRecordFields
551 ; (tc_avails, tc_fldss)
552 <- fmap unzip $ mapM (new_tc overload_ok)
553 (tyClGroupTyClDecls tycl_decls)
554 ; traceRn (text "getLocalNonValBinders 1" <+> ppr tc_avails)
555 ; envs <- extendGlobalRdrEnvRn tc_avails fixity_env
556 ; setEnvs envs $ do {
557 -- Bring these things into scope first
558 -- See Note [Looking up family names in family instances]
559
560 -- Process all family instances
561 -- to bring new data constructors into scope
562 ; (nti_availss, nti_fldss) <- mapAndUnzipM (new_assoc overload_ok)
563 inst_decls
564
565 -- Finish off with value binders:
566 -- foreign decls and pattern synonyms for an ordinary module
567 -- type sigs in case of a hs-boot file only
568 ; is_boot <- tcIsHsBootOrSig
569 ; let val_bndrs | is_boot = hs_boot_sig_bndrs
570 | otherwise = for_hs_bndrs
571 ; val_avails <- mapM new_simple val_bndrs
572
573 ; let avails = concat nti_availss ++ val_avails
574 new_bndrs = availsToNameSetWithSelectors avails `unionNameSet`
575 availsToNameSetWithSelectors tc_avails
576 flds = concat nti_fldss ++ concat tc_fldss
577 ; traceRn (text "getLocalNonValBinders 2" <+> ppr avails)
578 ; (tcg_env, tcl_env) <- extendGlobalRdrEnvRn avails fixity_env
579
580 -- Extend tcg_field_env with new fields (this used to be the
581 -- work of extendRecordFieldEnv)
582 ; let field_env = extendNameEnvList (tcg_field_env tcg_env) flds
583 envs = (tcg_env { tcg_field_env = field_env }, tcl_env)
584
585 ; traceRn (text "getLocalNonValBinders 3" <+> vcat [ppr flds, ppr field_env])
586 ; return (envs, new_bndrs) } }
587 where
588 ValBindsIn _val_binds val_sigs = binds
589
590 for_hs_bndrs :: [Located RdrName]
591 for_hs_bndrs = hsForeignDeclsBinders foreign_decls
592
593 -- In a hs-boot file, the value binders come from the
594 -- *signatures*, and there should be no foreign binders
595 hs_boot_sig_bndrs = [ L decl_loc (unLoc n)
596 | L decl_loc (TypeSig ns _) <- val_sigs, n <- ns]
597
598 -- the SrcSpan attached to the input should be the span of the
599 -- declaration, not just the name
600 new_simple :: Located RdrName -> RnM AvailInfo
601 new_simple rdr_name = do{ nm <- newTopSrcBinder rdr_name
602 ; return (avail nm) }
603
604 new_tc :: Bool -> LTyClDecl RdrName
605 -> RnM (AvailInfo, [(Name, [FieldLabel])])
606 new_tc overload_ok tc_decl -- NOT for type/data instances
607 = do { let (bndrs, flds) = hsLTyClDeclBinders tc_decl
608 ; names@(main_name : sub_names) <- mapM newTopSrcBinder bndrs
609 ; flds' <- mapM (newRecordSelector overload_ok sub_names) flds
610 ; let fld_env = case unLoc tc_decl of
611 DataDecl { tcdDataDefn = d } -> mk_fld_env d names flds'
612 _ -> []
613 ; return (AvailTC main_name names flds', fld_env) }
614
615
616 -- Calculate the mapping from constructor names to fields, which
617 -- will go in tcg_field_env. It's convenient to do this here where
618 -- we are working with a single datatype definition.
619 mk_fld_env :: HsDataDefn RdrName -> [Name] -> [FieldLabel] -> [(Name, [FieldLabel])]
620 mk_fld_env d names flds = concatMap find_con_flds (dd_cons d)
621 where
622 find_con_flds (L _ (ConDeclH98 { con_name = L _ rdr
623 , con_details = RecCon cdflds }))
624 = [( find_con_name rdr
625 , concatMap find_con_decl_flds (unLoc cdflds) )]
626 find_con_flds (L _ (ConDeclGADT
627 { con_names = rdrs
628 , con_type = (HsIB { hsib_body = res_ty})}))
629 = map (\ (L _ rdr) -> ( find_con_name rdr
630 , concatMap find_con_decl_flds cdflds))
631 rdrs
632 where
633 (_tvs, _cxt, tau) = splitLHsSigmaTy res_ty
634 cdflds = case tau of
635 L _ (HsFunTy
636 (L _ (HsAppsTy
637 [L _ (HsAppPrefix (L _ (HsRecTy flds)))])) _) -> flds
638 L _ (HsFunTy (L _ (HsRecTy flds)) _) -> flds
639 _ -> []
640 find_con_flds _ = []
641
642 find_con_name rdr
643 = expectJust "getLocalNonValBinders/find_con_name" $
644 find (\ n -> nameOccName n == rdrNameOcc rdr) names
645 find_con_decl_flds (L _ x)
646 = map find_con_decl_fld (cd_fld_names x)
647 find_con_decl_fld (L _ (FieldOcc (L _ rdr) _))
648 = expectJust "getLocalNonValBinders/find_con_decl_fld" $
649 find (\ fl -> flLabel fl == lbl) flds
650 where lbl = occNameFS (rdrNameOcc rdr)
651
652 new_assoc :: Bool -> LInstDecl RdrName
653 -> RnM ([AvailInfo], [(Name, [FieldLabel])])
654 new_assoc _ (L _ (TyFamInstD {})) = return ([], [])
655 -- type instances don't bind new names
656
657 new_assoc overload_ok (L _ (DataFamInstD d))
658 = do { (avail, flds) <- new_di overload_ok Nothing d
659 ; return ([avail], flds) }
660 new_assoc overload_ok (L _ (ClsInstD (ClsInstDecl { cid_poly_ty = inst_ty
661 , cid_datafam_insts = adts })))
662 | Just (L loc cls_rdr) <- getLHsInstDeclClass_maybe inst_ty
663 = do { cls_nm <- setSrcSpan loc $ lookupGlobalOccRn cls_rdr
664 ; (avails, fldss)
665 <- mapAndUnzipM (new_loc_di overload_ok (Just cls_nm)) adts
666 ; return (avails, concat fldss) }
667 | otherwise
668 = return ([], []) -- Do not crash on ill-formed instances
669 -- Eg instance !Show Int Trac #3811c
670
671 new_di :: Bool -> Maybe Name -> DataFamInstDecl RdrName
672 -> RnM (AvailInfo, [(Name, [FieldLabel])])
673 new_di overload_ok mb_cls ti_decl
674 = do { main_name <- lookupFamInstName mb_cls (dfid_tycon ti_decl)
675 ; let (bndrs, flds) = hsDataFamInstBinders ti_decl
676 ; sub_names <- mapM newTopSrcBinder bndrs
677 ; flds' <- mapM (newRecordSelector overload_ok sub_names) flds
678 ; let avail = AvailTC (unLoc main_name) sub_names flds'
679 -- main_name is not bound here!
680 fld_env = mk_fld_env (dfid_defn ti_decl) sub_names flds'
681 ; return (avail, fld_env) }
682
683 new_loc_di :: Bool -> Maybe Name -> LDataFamInstDecl RdrName
684 -> RnM (AvailInfo, [(Name, [FieldLabel])])
685 new_loc_di overload_ok mb_cls (L _ d) = new_di overload_ok mb_cls d
686
687 newRecordSelector :: Bool -> [Name] -> LFieldOcc RdrName -> RnM FieldLabel
688 newRecordSelector _ [] _ = error "newRecordSelector: datatype has no constructors!"
689 newRecordSelector overload_ok (dc:_) (L loc (FieldOcc (L _ fld) _))
690 = do { selName <- newTopSrcBinder $ L loc $ field
691 ; return $ qualFieldLbl { flSelector = selName } }
692 where
693 fieldOccName = occNameFS $ rdrNameOcc fld
694 qualFieldLbl = mkFieldLabelOccs fieldOccName (nameOccName dc) overload_ok
695 field | isExact fld = fld
696 -- use an Exact RdrName as is to preserve the bindings
697 -- of an already renamer-resolved field and its use
698 -- sites. This is needed to correctly support record
699 -- selectors in Template Haskell. See Note [Binders in
700 -- Template Haskell] in Convert.hs and Note [Looking up
701 -- Exact RdrNames] in RnEnv.hs.
702 | otherwise = mkRdrUnqual (flSelector qualFieldLbl)
703
704 {-
705 Note [Looking up family names in family instances]
706 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
707 Consider
708
709 module M where
710 type family T a :: *
711 type instance M.T Int = Bool
712
713 We might think that we can simply use 'lookupOccRn' when processing the type
714 instance to look up 'M.T'. Alas, we can't! The type family declaration is in
715 the *same* HsGroup as the type instance declaration. Hence, as we are
716 currently collecting the binders declared in that HsGroup, these binders will
717 not have been added to the global environment yet.
718
719 Solution is simple: process the type family declarations first, extend
720 the environment, and then process the type instances.
721
722
723 ************************************************************************
724 * *
725 \subsection{Filtering imports}
726 * *
727 ************************************************************************
728
729 @filterImports@ takes the @ExportEnv@ telling what the imported module makes
730 available, and filters it through the import spec (if any).
731
732 Note [Dealing with imports]
733 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
734 For import M( ies ), we take the mi_exports of M, and make
735 imp_occ_env :: OccEnv (Name, AvailInfo, Maybe Name)
736 One entry for each Name that M exports; the AvailInfo describes just
737 that Name.
738
739 The situation is made more complicated by associated types. E.g.
740 module M where
741 class C a where { data T a }
742 instance C Int where { data T Int = T1 | T2 }
743 instance C Bool where { data T Int = T3 }
744 Then M's export_avails are (recall the AvailTC invariant from Avails.hs)
745 C(C,T), T(T,T1,T2,T3)
746 Notice that T appears *twice*, once as a child and once as a parent.
747 From this we construct the imp_occ_env
748 C -> (C, C(C,T), Nothing)
749 T -> (T, T(T,T1,T2,T3), Just C)
750 T1 -> (T1, T(T1,T2,T3), Nothing) -- similarly T2,T3
751
752 If we say
753 import M( T(T1,T2) )
754 then we get *two* Avails: C(T), T(T1,T2)
755
756 Note that the imp_occ_env will have entries for data constructors too,
757 although we never look up data constructors.
758 -}
759
760 filterImports
761 :: ModIface
762 -> ImpDeclSpec -- The span for the entire import decl
763 -> Maybe (Bool, Located [LIE RdrName]) -- Import spec; True => hiding
764 -> RnM (Maybe (Bool, Located [LIE Name]), -- Import spec w/ Names
765 [GlobalRdrElt]) -- Same again, but in GRE form
766 filterImports iface decl_spec Nothing
767 = return (Nothing, gresFromAvails (Just imp_spec) (mi_exports iface))
768 where
769 imp_spec = ImpSpec { is_decl = decl_spec, is_item = ImpAll }
770
771
772 filterImports iface decl_spec (Just (want_hiding, L l import_items))
773 = do -- check for errors, convert RdrNames to Names
774 items1 <- mapM lookup_lie import_items
775
776 let items2 :: [(LIE Name, AvailInfo)]
777 items2 = concat items1
778 -- NB the AvailInfo may have duplicates, and several items
779 -- for the same parent; e.g N(x) and N(y)
780
781 names = availsToNameSet (map snd items2)
782 keep n = not (n `elemNameSet` names)
783 pruned_avails = filterAvails keep all_avails
784 hiding_spec = ImpSpec { is_decl = decl_spec, is_item = ImpAll }
785
786 gres | want_hiding = gresFromAvails (Just hiding_spec) pruned_avails
787 | otherwise = concatMap (gresFromIE decl_spec) items2
788
789 return (Just (want_hiding, L l (map fst items2)), gres)
790 where
791 all_avails = mi_exports iface
792
793 -- See Note [Dealing with imports]
794 imp_occ_env :: OccEnv (Name, -- the name
795 AvailInfo, -- the export item providing the name
796 Maybe Name) -- the parent of associated types
797 imp_occ_env = mkOccEnv_C combine [ (nameOccName n, (n, a, Nothing))
798 | a <- all_avails, n <- availNames a]
799 where
800 -- See example in Note [Dealing with imports]
801 -- 'combine' is only called for associated types which appear twice
802 -- in the all_avails. In the example, we combine
803 -- T(T,T1,T2,T3) and C(C,T) to give (T, T(T,T1,T2,T3), Just C)
804 combine (name1, a1@(AvailTC p1 _ []), mp1)
805 (name2, a2@(AvailTC p2 _ []), mp2)
806 = ASSERT( name1 == name2 && isNothing mp1 && isNothing mp2 )
807 if p1 == name1 then (name1, a1, Just p2)
808 else (name1, a2, Just p1)
809 combine x y = pprPanic "filterImports/combine" (ppr x $$ ppr y)
810
811 lookup_name :: RdrName -> IELookupM (Name, AvailInfo, Maybe Name)
812 lookup_name rdr | isQual rdr = failLookupWith (QualImportError rdr)
813 | Just succ <- mb_success = return succ
814 | otherwise = failLookupWith BadImport
815 where
816 mb_success = lookupOccEnv imp_occ_env (rdrNameOcc rdr)
817
818 lookup_lie :: LIE RdrName -> TcRn [(LIE Name, AvailInfo)]
819 lookup_lie (L loc ieRdr)
820 = do (stuff, warns) <- setSrcSpan loc $
821 liftM (fromMaybe ([],[])) $
822 run_lookup (lookup_ie ieRdr)
823 mapM_ emit_warning warns
824 return [ (L loc ie, avail) | (ie,avail) <- stuff ]
825 where
826 -- Warn when importing T(..) if T was exported abstractly
827 emit_warning (DodgyImport n) = whenWOptM Opt_WarnDodgyImports $
828 addWarn (Reason Opt_WarnDodgyImports) (dodgyImportWarn n)
829 emit_warning MissingImportList = whenWOptM Opt_WarnMissingImportList $
830 addWarn (Reason Opt_WarnMissingImportList) (missingImportListItem ieRdr)
831 emit_warning BadImportW = whenWOptM Opt_WarnDodgyImports $
832 addWarn (Reason Opt_WarnDodgyImports) (lookup_err_msg BadImport)
833
834 run_lookup :: IELookupM a -> TcRn (Maybe a)
835 run_lookup m = case m of
836 Failed err -> addErr (lookup_err_msg err) >> return Nothing
837 Succeeded a -> return (Just a)
838
839 lookup_err_msg err = case err of
840 BadImport -> badImportItemErr iface decl_spec ieRdr all_avails
841 IllegalImport -> illegalImportItemErr
842 QualImportError rdr -> qualImportItemErr rdr
843
844 -- For each import item, we convert its RdrNames to Names,
845 -- and at the same time construct an AvailInfo corresponding
846 -- to what is actually imported by this item.
847 -- Returns Nothing on error.
848 -- We return a list here, because in the case of an import
849 -- item like C, if we are hiding, then C refers to *both* a
850 -- type/class and a data constructor. Moreover, when we import
851 -- data constructors of an associated family, we need separate
852 -- AvailInfos for the data constructors and the family (as they have
853 -- different parents). See Note [Dealing with imports]
854 lookup_ie :: IE RdrName -> IELookupM ([(IE Name, AvailInfo)], [IELookupWarning])
855 lookup_ie ie = handle_bad_import $ do
856 case ie of
857 IEVar (L l n) -> do
858 (name, avail, _) <- lookup_name n
859 return ([(IEVar (L l name), trimAvail avail name)], [])
860
861 IEThingAll (L l tc) -> do
862 (name, avail, mb_parent) <- lookup_name tc
863 let warns = case avail of
864 Avail {} -- e.g. f(..)
865 -> [DodgyImport tc]
866
867 AvailTC _ subs fs
868 | null (drop 1 subs) && null fs -- e.g. T(..) where T is a synonym
869 -> [DodgyImport tc]
870
871 | not (is_qual decl_spec) -- e.g. import M( T(..) )
872 -> [MissingImportList]
873
874 | otherwise
875 -> []
876
877 renamed_ie = IEThingAll (L l name)
878 sub_avails = case avail of
879 Avail {} -> []
880 AvailTC name2 subs fs -> [(renamed_ie, AvailTC name2 (subs \\ [name]) fs)]
881 case mb_parent of
882 Nothing -> return ([(renamed_ie, avail)], warns)
883 -- non-associated ty/cls
884 Just parent -> return ((renamed_ie, AvailTC parent [name] []) : sub_avails, warns)
885 -- associated type
886
887 IEThingAbs (L l tc)
888 | want_hiding -- hiding ( C )
889 -- Here the 'C' can be a data constructor
890 -- *or* a type/class, or even both
891 -> let tc_name = lookup_name tc
892 dc_name = lookup_name (setRdrNameSpace tc srcDataName)
893 in
894 case catIELookupM [ tc_name, dc_name ] of
895 [] -> failLookupWith BadImport
896 names -> return ([mkIEThingAbs l name | name <- names], [])
897 | otherwise
898 -> do nameAvail <- lookup_name tc
899 return ([mkIEThingAbs l nameAvail], [])
900
901 IEThingWith (L l rdr_tc) wc rdr_ns rdr_fs ->
902 ASSERT2(null rdr_fs, ppr rdr_fs) do
903 (name, AvailTC _ ns subflds, mb_parent) <- lookup_name rdr_tc
904
905 -- Look up the children in the sub-names of the parent
906 let subnames = case ns of -- The tc is first in ns,
907 [] -> [] -- if it is there at all
908 -- See the AvailTC Invariant in Avail.hs
909 (n1:ns1) | n1 == name -> ns1
910 | otherwise -> ns
911 case lookupChildren (map Left subnames ++ map Right subflds) rdr_ns of
912 Nothing -> failLookupWith BadImport
913 Just (childnames, childflds) ->
914 case mb_parent of
915 -- non-associated ty/cls
916 Nothing
917 -> return ([(IEThingWith (L l name) wc childnames childflds,
918 AvailTC name (name:map unLoc childnames) (map unLoc childflds))],
919 [])
920 -- associated ty
921 Just parent
922 -> return ([(IEThingWith (L l name) wc childnames childflds,
923 AvailTC name (map unLoc childnames) (map unLoc childflds)),
924 (IEThingWith (L l name) wc childnames childflds,
925 AvailTC parent [name] [])],
926 [])
927
928 _other -> failLookupWith IllegalImport
929 -- could be IEModuleContents, IEGroup, IEDoc, IEDocNamed
930 -- all errors.
931
932 where
933 mkIEThingAbs l (n, av, Nothing ) = (IEThingAbs (L l n),
934 trimAvail av n)
935 mkIEThingAbs l (n, _, Just parent) = (IEThingAbs (L l n),
936 AvailTC parent [n] [])
937
938 handle_bad_import m = catchIELookup m $ \err -> case err of
939 BadImport | want_hiding -> return ([], [BadImportW])
940 _ -> failLookupWith err
941
942 type IELookupM = MaybeErr IELookupError
943
944 data IELookupWarning
945 = BadImportW
946 | MissingImportList
947 | DodgyImport RdrName
948 -- NB. use the RdrName for reporting a "dodgy" import
949
950 data IELookupError
951 = QualImportError RdrName
952 | BadImport
953 | IllegalImport
954
955 failLookupWith :: IELookupError -> IELookupM a
956 failLookupWith err = Failed err
957
958 catchIELookup :: IELookupM a -> (IELookupError -> IELookupM a) -> IELookupM a
959 catchIELookup m h = case m of
960 Succeeded r -> return r
961 Failed err -> h err
962
963 catIELookupM :: [IELookupM a] -> [a]
964 catIELookupM ms = [ a | Succeeded a <- ms ]
965
966 {-
967 ************************************************************************
968 * *
969 \subsection{Import/Export Utils}
970 * *
971 ************************************************************************
972 -}
973
974 plusAvail :: AvailInfo -> AvailInfo -> AvailInfo
975 plusAvail a1 a2
976 | debugIsOn && availName a1 /= availName a2
977 = pprPanic "RnEnv.plusAvail names differ" (hsep [ppr a1,ppr a2])
978 plusAvail a1@(Avail {}) (Avail {}) = a1
979 plusAvail (AvailTC _ [] []) a2@(AvailTC {}) = a2
980 plusAvail a1@(AvailTC {}) (AvailTC _ [] []) = a1
981 plusAvail (AvailTC n1 (s1:ss1) fs1) (AvailTC n2 (s2:ss2) fs2)
982 = case (n1==s1, n2==s2) of -- Maintain invariant the parent is first
983 (True,True) -> AvailTC n1 (s1 : (ss1 `unionLists` ss2))
984 (fs1 `unionLists` fs2)
985 (True,False) -> AvailTC n1 (s1 : (ss1 `unionLists` (s2:ss2)))
986 (fs1 `unionLists` fs2)
987 (False,True) -> AvailTC n1 (s2 : ((s1:ss1) `unionLists` ss2))
988 (fs1 `unionLists` fs2)
989 (False,False) -> AvailTC n1 ((s1:ss1) `unionLists` (s2:ss2))
990 (fs1 `unionLists` fs2)
991 plusAvail (AvailTC n1 ss1 fs1) (AvailTC _ [] fs2)
992 = AvailTC n1 ss1 (fs1 `unionLists` fs2)
993 plusAvail (AvailTC n1 [] fs1) (AvailTC _ ss2 fs2)
994 = AvailTC n1 ss2 (fs1 `unionLists` fs2)
995 plusAvail a1 a2 = pprPanic "RnEnv.plusAvail" (hsep [ppr a1,ppr a2])
996
997 -- | trims an 'AvailInfo' to keep only a single name
998 trimAvail :: AvailInfo -> Name -> AvailInfo
999 trimAvail (Avail b n) _ = Avail b n
1000 trimAvail (AvailTC n ns fs) m = case find ((== m) . flSelector) fs of
1001 Just x -> AvailTC n [] [x]
1002 Nothing -> ASSERT( m `elem` ns ) AvailTC n [m] []
1003
1004 -- | filters 'AvailInfo's by the given predicate
1005 filterAvails :: (Name -> Bool) -> [AvailInfo] -> [AvailInfo]
1006 filterAvails keep avails = foldr (filterAvail keep) [] avails
1007
1008 -- | filters an 'AvailInfo' by the given predicate
1009 filterAvail :: (Name -> Bool) -> AvailInfo -> [AvailInfo] -> [AvailInfo]
1010 filterAvail keep ie rest =
1011 case ie of
1012 Avail _ n | keep n -> ie : rest
1013 | otherwise -> rest
1014 AvailTC tc ns fs ->
1015 let ns' = filter keep ns
1016 fs' = filter (keep . flSelector) fs in
1017 if null ns' && null fs' then rest else AvailTC tc ns' fs' : rest
1018
1019 -- | Given an import\/export spec, construct the appropriate 'GlobalRdrElt's.
1020 gresFromIE :: ImpDeclSpec -> (LIE Name, AvailInfo) -> [GlobalRdrElt]
1021 gresFromIE decl_spec (L loc ie, avail)
1022 = gresFromAvail prov_fn avail
1023 where
1024 is_explicit = case ie of
1025 IEThingAll (L _ name) -> \n -> n == name
1026 _ -> \_ -> True
1027 prov_fn name
1028 = Just (ImpSpec { is_decl = decl_spec, is_item = item_spec })
1029 where
1030 item_spec = ImpSome { is_explicit = is_explicit name, is_iloc = loc }
1031
1032
1033 {-
1034 Note [Children for duplicate record fields]
1035 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1036 Consider the module
1037
1038 {-# LANGUAGE DuplicateRecordFields #-}
1039 module M (F(foo, MkFInt, MkFBool)) where
1040 data family F a
1041 data instance F Int = MkFInt { foo :: Int }
1042 data instance F Bool = MkFBool { foo :: Bool }
1043
1044 The `foo` in the export list refers to *both* selectors! For this
1045 reason, lookupChildren builds an environment that maps the FastString
1046 to a list of items, rather than a single item.
1047 -}
1048
1049 mkChildEnv :: [GlobalRdrElt] -> NameEnv [GlobalRdrElt]
1050 mkChildEnv gres = foldr add emptyNameEnv gres
1051 where
1052 add gre env = case gre_par gre of
1053 FldParent p _ -> extendNameEnv_Acc (:) singleton env p gre
1054 ParentIs p -> extendNameEnv_Acc (:) singleton env p gre
1055 NoParent -> env
1056 PatternSynonym -> env
1057
1058 findPatSyns :: [GlobalRdrElt] -> [GlobalRdrElt]
1059 findPatSyns gres = foldr add [] gres
1060 where
1061 add g@(GRE { gre_par = PatternSynonym }) ps =
1062 g:ps
1063 add _ ps = ps
1064
1065 findChildren :: NameEnv [a] -> Name -> [a]
1066 findChildren env n = lookupNameEnv env n `orElse` []
1067
1068 lookupChildren :: [Either Name FieldLabel] -> [Located RdrName]
1069 -> Maybe ([Located Name], [Located FieldLabel])
1070 -- (lookupChildren all_kids rdr_items) maps each rdr_item to its
1071 -- corresponding Name all_kids, if the former exists
1072 -- The matching is done by FastString, not OccName, so that
1073 -- Cls( meth, AssocTy )
1074 -- will correctly find AssocTy among the all_kids of Cls, even though
1075 -- the RdrName for AssocTy may have a (bogus) DataName namespace
1076 -- (Really the rdr_items should be FastStrings in the first place.)
1077 lookupChildren all_kids rdr_items
1078 = do xs <- mapM doOne rdr_items
1079 return (fmap concat (partitionEithers xs))
1080 where
1081 doOne (L l r) = case (lookupFsEnv kid_env . occNameFS . rdrNameOcc) r of
1082 Just [Left n] -> Just (Left (L l n))
1083 Just rs | all isRight rs -> Just (Right (map (L l) (rights rs)))
1084 _ -> Nothing
1085
1086 -- See Note [Children for duplicate record fields]
1087 kid_env = extendFsEnvList_C (++) emptyFsEnv
1088 [(either (occNameFS . nameOccName) flLabel x, [x]) | x <- all_kids]
1089
1090
1091 classifyGREs :: [GlobalRdrElt] -> ([Name], [FieldLabel])
1092 classifyGREs = partitionEithers . map classifyGRE
1093
1094 classifyGRE :: GlobalRdrElt -> Either Name FieldLabel
1095 classifyGRE gre = case gre_par gre of
1096 FldParent _ Nothing -> Right (FieldLabel (occNameFS (nameOccName n)) False n)
1097 FldParent _ (Just lbl) -> Right (FieldLabel lbl True n)
1098 _ -> Left n
1099 where
1100 n = gre_name gre
1101
1102 -- | Combines 'AvailInfo's from the same family
1103 -- 'avails' may have several items with the same availName
1104 -- E.g import Ix( Ix(..), index )
1105 -- will give Ix(Ix,index,range) and Ix(index)
1106 -- We want to combine these; addAvail does that
1107 nubAvails :: [AvailInfo] -> [AvailInfo]
1108 nubAvails avails = nameEnvElts (foldl add emptyNameEnv avails)
1109 where
1110 add env avail = extendNameEnv_C plusAvail env (availName avail) avail
1111
1112 {-
1113 ************************************************************************
1114 * *
1115 \subsection{Export list processing}
1116 * *
1117 ************************************************************************
1118
1119 Processing the export list.
1120
1121 You might think that we should record things that appear in the export
1122 list as ``occurrences'' (using @addOccurrenceName@), but you'd be
1123 wrong. We do check (here) that they are in scope, but there is no
1124 need to slurp in their actual declaration (which is what
1125 @addOccurrenceName@ forces).
1126
1127 Indeed, doing so would big trouble when compiling @PrelBase@, because
1128 it re-exports @GHC@, which includes @takeMVar#@, whose type includes
1129 @ConcBase.StateAndSynchVar#@, and so on...
1130
1131 Note [Exports of data families]
1132 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1133 Suppose you see (Trac #5306)
1134 module M where
1135 import X( F )
1136 data instance F Int = FInt
1137 What does M export? AvailTC F [FInt]
1138 or AvailTC F [F,FInt]?
1139 The former is strictly right because F isn't defined in this module.
1140 But then you can never do an explicit import of M, thus
1141 import M( F( FInt ) )
1142 because F isn't exported by M. Nor can you import FInt alone from here
1143 import M( FInt )
1144 because we don't have syntax to support that. (It looks like an import of
1145 the type FInt.)
1146
1147 At one point I implemented a compromise:
1148 * When constructing exports with no export list, or with module M(
1149 module M ), we add the parent to the exports as well.
1150 * But not when you see module M( f ), even if f is a
1151 class method with a parent.
1152 * Nor when you see module M( module N ), with N /= M.
1153
1154 But the compromise seemed too much of a hack, so we backed it out.
1155 You just have to use an explicit export list:
1156 module M( F(..) ) where ...
1157 -}
1158
1159 type ExportAccum -- The type of the accumulating parameter of
1160 -- the main worker function in rnExports
1161 = ([LIE Name], -- Export items with Names
1162 ExportOccMap, -- Tracks exported occurrence names
1163 [AvailInfo]) -- The accumulated exported stuff
1164 -- Not nub'd!
1165
1166 emptyExportAccum :: ExportAccum
1167 emptyExportAccum = ([], emptyOccEnv, [])
1168
1169 type ExportOccMap = OccEnv (Name, IE RdrName)
1170 -- Tracks what a particular exported OccName
1171 -- in an export list refers to, and which item
1172 -- it came from. It's illegal to export two distinct things
1173 -- that have the same occurrence name
1174
1175 rnExports :: Bool -- False => no 'module M(..) where' header at all
1176 -> Maybe (Located [LIE RdrName]) -- Nothing => no explicit export list
1177 -> TcGblEnv
1178 -> RnM (Maybe [LIE Name], TcGblEnv)
1179
1180 -- Complains if two distinct exports have same OccName
1181 -- Warns about identical exports.
1182 -- Complains about exports items not in scope
1183
1184 rnExports explicit_mod exports
1185 tcg_env@(TcGblEnv { tcg_mod = this_mod,
1186 tcg_rdr_env = rdr_env,
1187 tcg_imports = imports })
1188 = unsetWOptM Opt_WarnWarningsDeprecations $
1189 -- Do not report deprecations arising from the export
1190 -- list, to avoid bleating about re-exporting a deprecated
1191 -- thing (especially via 'module Foo' export item)
1192 do {
1193 -- If the module header is omitted altogether, then behave
1194 -- as if the user had written "module Main(main) where..."
1195 -- EXCEPT in interactive mode, when we behave as if he had
1196 -- written "module Main where ..."
1197 -- Reason: don't want to complain about 'main' not in scope
1198 -- in interactive mode
1199 ; dflags <- getDynFlags
1200 ; let real_exports
1201 | explicit_mod = exports
1202 | ghcLink dflags == LinkInMemory = Nothing
1203 | otherwise
1204 = Just (noLoc [noLoc (IEVar (noLoc main_RDR_Unqual))])
1205 -- ToDo: the 'noLoc' here is unhelpful if 'main'
1206 -- turns out to be out of scope
1207
1208 ; (rn_exports, avails) <- exports_from_avail real_exports rdr_env imports this_mod
1209 ; traceRn (ppr avails)
1210 ; let final_avails = nubAvails avails -- Combine families
1211 final_ns = availsToNameSetWithSelectors final_avails
1212
1213 ; traceRn (text "rnExports: Exports:" <+> ppr final_avails)
1214
1215 ; let new_tcg_env =
1216 (tcg_env { tcg_exports = final_avails,
1217 tcg_rn_exports = case tcg_rn_exports tcg_env of
1218 Nothing -> Nothing
1219 Just _ -> rn_exports,
1220 tcg_dus = tcg_dus tcg_env `plusDU`
1221 usesOnly final_ns })
1222 ; return (rn_exports, new_tcg_env) }
1223
1224 exports_from_avail :: Maybe (Located [LIE RdrName])
1225 -- Nothing => no explicit export list
1226 -> GlobalRdrEnv
1227 -> ImportAvails
1228 -> Module
1229 -> RnM (Maybe [LIE Name], [AvailInfo])
1230
1231 exports_from_avail Nothing rdr_env _imports _this_mod
1232 -- The same as (module M) where M is the current module name,
1233 -- so that's how we handle it, except we also export the data family
1234 -- when a data instance is exported.
1235 = let avails = [ fix_faminst $ availFromGRE gre
1236 | gre <- globalRdrEnvElts rdr_env
1237 , isLocalGRE gre ]
1238 in return (Nothing, avails)
1239 where
1240 -- #11164: when we define a data instance
1241 -- but not data family, re-export the family
1242 -- Even though we don't check whether this is actually a data family
1243 -- only data families can locally define subordinate things (`ns` here)
1244 -- without locally defining (and instead importing) the parent (`n`)
1245 fix_faminst (AvailTC n ns flds)
1246 | not (n `elem` ns)
1247 = AvailTC n (n:ns) flds
1248
1249 fix_faminst avail = avail
1250
1251
1252 exports_from_avail (Just (L _ rdr_items)) rdr_env imports this_mod
1253 = do (ie_names, _, exports) <- foldlM do_litem emptyExportAccum rdr_items
1254 return (Just ie_names, exports)
1255 where
1256 do_litem :: ExportAccum -> LIE RdrName -> RnM ExportAccum
1257 do_litem acc lie = setSrcSpan (getLoc lie) (exports_from_item acc lie)
1258
1259 -- Maps a parent to its in-scope children
1260 kids_env :: NameEnv [GlobalRdrElt]
1261 kids_env = mkChildEnv (globalRdrEnvElts rdr_env)
1262
1263 pat_syns :: [GlobalRdrElt]
1264 pat_syns = findPatSyns (globalRdrEnvElts rdr_env)
1265
1266 imported_modules = [ imv_name imv
1267 | xs <- moduleEnvElts $ imp_mods imports, imv <- xs ]
1268
1269 exports_from_item :: ExportAccum -> LIE RdrName -> RnM ExportAccum
1270 exports_from_item acc@(ie_names, occs, exports)
1271 (L loc (IEModuleContents (L lm mod)))
1272 | let earlier_mods = [ mod
1273 | (L _ (IEModuleContents (L _ mod))) <- ie_names ]
1274 , mod `elem` earlier_mods -- Duplicate export of M
1275 = do { warn_dup_exports <- woptM Opt_WarnDuplicateExports ;
1276 warnIf (Reason Opt_WarnDuplicateExports) warn_dup_exports
1277 (dupModuleExport mod) ;
1278 return acc }
1279
1280 | otherwise
1281 = do { warnDodgyExports <- woptM Opt_WarnDodgyExports
1282 ; let { exportValid = (mod `elem` imported_modules)
1283 || (moduleName this_mod == mod)
1284 ; gre_prs = pickGREsModExp mod (globalRdrEnvElts rdr_env)
1285 ; new_exports = map (availFromGRE . fst) gre_prs
1286 ; names = map (gre_name . fst) gre_prs
1287 ; all_gres = foldr (\(gre1,gre2) gres -> gre1 : gre2 : gres) [] gre_prs
1288 }
1289
1290 ; checkErr exportValid (moduleNotImported mod)
1291 ; warnIf (Reason Opt_WarnDodgyExports)
1292 (warnDodgyExports && exportValid && null gre_prs)
1293 (nullModuleExport mod)
1294
1295 ; traceRn (text "efa" <+> (ppr mod $$ ppr all_gres))
1296 ; addUsedGREs all_gres
1297
1298 ; occs' <- check_occs (IEModuleContents (noLoc mod)) occs names
1299 -- This check_occs not only finds conflicts
1300 -- between this item and others, but also
1301 -- internally within this item. That is, if
1302 -- 'M.x' is in scope in several ways, we'll have
1303 -- several members of mod_avails with the same
1304 -- OccName.
1305 ; traceRn (vcat [ text "export mod" <+> ppr mod
1306 , ppr new_exports ])
1307 ; return (L loc (IEModuleContents (L lm mod)) : ie_names,
1308 occs', new_exports ++ exports) }
1309
1310 exports_from_item acc@(lie_names, occs, exports) (L loc ie)
1311 | isDoc ie
1312 = do new_ie <- lookup_doc_ie ie
1313 return (L loc new_ie : lie_names, occs, exports)
1314
1315 | otherwise
1316 = do (new_ie, avail) <- lookup_ie ie
1317 if isUnboundName (ieName new_ie)
1318 then return acc -- Avoid error cascade
1319 else do
1320
1321 occs' <- check_occs ie occs (availNames avail)
1322
1323 return (L loc new_ie : lie_names, occs', avail : exports)
1324
1325 -------------
1326 lookup_ie :: IE RdrName -> RnM (IE Name, AvailInfo)
1327 lookup_ie (IEVar (L l rdr))
1328 = do (name, avail) <- lookupGreAvailRn rdr
1329 return (IEVar (L l name), avail)
1330
1331 lookup_ie (IEThingAbs (L l rdr))
1332 = do (name, avail) <- lookupGreAvailRn rdr
1333 return (IEThingAbs (L l name), avail)
1334
1335 lookup_ie ie@(IEThingAll n)
1336 = do
1337 (n, avail, flds) <- lookup_ie_all ie n
1338 let name = unLoc n
1339 return (IEThingAll n, AvailTC name (name:avail) flds)
1340
1341
1342 lookup_ie ie@(IEThingWith l wc sub_rdrs _)
1343 = do
1344 (lname, subs, avails, flds) <- lookup_ie_with ie l sub_rdrs
1345 (_, all_avail, all_flds) <-
1346 case wc of
1347 NoIEWildcard -> return (lname, [], [])
1348 IEWildcard _ -> lookup_ie_all ie l
1349 let name = unLoc lname
1350 return (IEThingWith lname wc subs [],
1351 AvailTC name (name : avails ++ all_avail)
1352 (flds ++ all_flds))
1353
1354
1355
1356
1357 lookup_ie _ = panic "lookup_ie" -- Other cases covered earlier
1358
1359 lookup_ie_with :: IE RdrName -> Located RdrName -> [Located RdrName]
1360 -> RnM (Located Name, [Located Name], [Name], [FieldLabel])
1361 lookup_ie_with ie (L l rdr) sub_rdrs
1362 = do name <- lookupGlobalOccRnExport rdr
1363 let gres = findChildren kids_env name
1364 mchildren =
1365 lookupChildren (map classifyGRE (gres ++ pat_syns)) sub_rdrs
1366 addUsedKids rdr gres
1367 if isUnboundName name
1368 then return (L l name, [], [name], [])
1369 else
1370 case mchildren of
1371 Nothing -> do
1372 addErr (exportItemErr ie)
1373 return (L l name, [], [name], [])
1374 Just (non_flds, flds) -> do
1375 addUsedKids rdr gres
1376 return (L l name, non_flds
1377 , map unLoc non_flds
1378 , map unLoc flds)
1379 lookup_ie_all :: IE RdrName -> Located RdrName
1380 -> RnM (Located Name, [Name], [FieldLabel])
1381 lookup_ie_all ie (L l rdr) =
1382 do name <- lookupGlobalOccRnExport rdr
1383 let gres = findChildren kids_env name
1384 (non_flds, flds) = classifyGREs gres
1385 addUsedKids rdr gres
1386 warnDodgyExports <- woptM Opt_WarnDodgyExports
1387 when (null gres) $
1388 if isTyConName name
1389 then when warnDodgyExports $
1390 addWarn (Reason Opt_WarnDodgyExports)
1391 (dodgyExportWarn name)
1392 else -- This occurs when you export T(..), but
1393 -- only import T abstractly, or T is a synonym.
1394 addErr (exportItemErr ie)
1395 return (L l name, non_flds, flds)
1396
1397 -------------
1398 lookup_doc_ie :: IE RdrName -> RnM (IE Name)
1399 lookup_doc_ie (IEGroup lev doc) = do rn_doc <- rnHsDoc doc
1400 return (IEGroup lev rn_doc)
1401 lookup_doc_ie (IEDoc doc) = do rn_doc <- rnHsDoc doc
1402 return (IEDoc rn_doc)
1403 lookup_doc_ie (IEDocNamed str) = return (IEDocNamed str)
1404 lookup_doc_ie _ = panic "lookup_doc_ie" -- Other cases covered earlier
1405
1406 -- In an export item M.T(A,B,C), we want to treat the uses of
1407 -- A,B,C as if they were M.A, M.B, M.C
1408 -- Happily pickGREs does just the right thing
1409 addUsedKids :: RdrName -> [GlobalRdrElt] -> RnM ()
1410 addUsedKids parent_rdr kid_gres = addUsedGREs (pickGREs parent_rdr kid_gres)
1411
1412 isDoc :: IE RdrName -> Bool
1413 isDoc (IEDoc _) = True
1414 isDoc (IEDocNamed _) = True
1415 isDoc (IEGroup _ _) = True
1416 isDoc _ = False
1417
1418
1419 -------------------------------
1420 check_occs :: IE RdrName -> ExportOccMap -> [Name] -> RnM ExportOccMap
1421 check_occs ie occs names -- 'names' are the entities specifed by 'ie'
1422 = foldlM check occs names
1423 where
1424 check occs name
1425 = case lookupOccEnv occs name_occ of
1426 Nothing -> return (extendOccEnv occs name_occ (name, ie))
1427
1428 Just (name', ie')
1429 | name == name' -- Duplicate export
1430 -- But we don't want to warn if the same thing is exported
1431 -- by two different module exports. See ticket #4478.
1432 -> do unless (dupExport_ok name ie ie') $ do
1433 warn_dup_exports <- woptM Opt_WarnDuplicateExports
1434 warnIf (Reason Opt_WarnDuplicateExports) warn_dup_exports
1435 (dupExportWarn name_occ ie ie')
1436 return occs
1437
1438 | otherwise -- Same occ name but different names: an error
1439 -> do { global_env <- getGlobalRdrEnv ;
1440 addErr (exportClashErr global_env name' name ie' ie) ;
1441 return occs }
1442 where
1443 name_occ = nameOccName name
1444
1445
1446 dupExport_ok :: Name -> IE RdrName -> IE RdrName -> Bool
1447 -- The Name is exported by both IEs. Is that ok?
1448 -- "No" iff the name is mentioned explicitly in both IEs
1449 -- or one of the IEs mentions the name *alone*
1450 -- "Yes" otherwise
1451 --
1452 -- Examples of "no": module M( f, f )
1453 -- module M( fmap, Functor(..) )
1454 -- module M( module Data.List, head )
1455 --
1456 -- Example of "yes"
1457 -- module M( module A, module B ) where
1458 -- import A( f )
1459 -- import B( f )
1460 --
1461 -- Example of "yes" (Trac #2436)
1462 -- module M( C(..), T(..) ) where
1463 -- class C a where { data T a }
1464 -- instace C Int where { data T Int = TInt }
1465 --
1466 -- Example of "yes" (Trac #2436)
1467 -- module Foo ( T ) where
1468 -- data family T a
1469 -- module Bar ( T(..), module Foo ) where
1470 -- import Foo
1471 -- data instance T Int = TInt
1472
1473 dupExport_ok n ie1 ie2
1474 = not ( single ie1 || single ie2
1475 || (explicit_in ie1 && explicit_in ie2) )
1476 where
1477 explicit_in (IEModuleContents _) = False -- module M
1478 explicit_in (IEThingAll r) = nameOccName n == rdrNameOcc (unLoc r) -- T(..)
1479 explicit_in _ = True
1480
1481 single (IEVar {}) = True
1482 single (IEThingAbs {}) = True
1483 single _ = False
1484
1485 {-
1486 *********************************************************
1487 * *
1488 \subsection{Unused names}
1489 * *
1490 *********************************************************
1491 -}
1492
1493 reportUnusedNames :: Maybe (Located [LIE RdrName]) -- Export list
1494 -> TcGblEnv -> RnM ()
1495 reportUnusedNames _export_decls gbl_env
1496 = do { traceRn ((text "RUN") <+> (ppr (tcg_dus gbl_env)))
1497 ; warnUnusedImportDecls gbl_env
1498 ; warnUnusedTopBinds unused_locals
1499 ; warnMissingSignatures gbl_env }
1500 where
1501 used_names :: NameSet
1502 used_names = findUses (tcg_dus gbl_env) emptyNameSet
1503 -- NB: currently, if f x = g, we only treat 'g' as used if 'f' is used
1504 -- Hence findUses
1505
1506 -- Collect the defined names from the in-scope environment
1507 defined_names :: [GlobalRdrElt]
1508 defined_names = globalRdrEnvElts (tcg_rdr_env gbl_env)
1509
1510 -- Note that defined_and_used, defined_but_not_used
1511 -- are both [GRE]; that's why we need defined_and_used
1512 -- rather than just used_names
1513 _defined_and_used, defined_but_not_used :: [GlobalRdrElt]
1514 (_defined_and_used, defined_but_not_used)
1515 = partition (gre_is_used used_names) defined_names
1516
1517 kids_env = mkChildEnv defined_names
1518 -- This is done in mkExports too; duplicated work
1519
1520 gre_is_used :: NameSet -> GlobalRdrElt -> Bool
1521 gre_is_used used_names (GRE {gre_name = name})
1522 = name `elemNameSet` used_names
1523 || any (\ gre -> gre_name gre `elemNameSet` used_names) (findChildren kids_env name)
1524 -- A use of C implies a use of T,
1525 -- if C was brought into scope by T(..) or T(C)
1526
1527 -- Filter out the ones that are
1528 -- (a) defined in this module, and
1529 -- (b) not defined by a 'deriving' clause
1530 -- The latter have an Internal Name, so we can filter them out easily
1531 unused_locals :: [GlobalRdrElt]
1532 unused_locals = filter is_unused_local defined_but_not_used
1533 is_unused_local :: GlobalRdrElt -> Bool
1534 is_unused_local gre = isLocalGRE gre && isExternalName (gre_name gre)
1535
1536 {-
1537 *********************************************************
1538 * *
1539 \subsection{Unused imports}
1540 * *
1541 *********************************************************
1542
1543 This code finds which import declarations are unused. The
1544 specification and implementation notes are here:
1545 http://ghc.haskell.org/trac/ghc/wiki/Commentary/Compiler/UnusedImports
1546 -}
1547
1548 type ImportDeclUsage
1549 = ( LImportDecl Name -- The import declaration
1550 , [AvailInfo] -- What *is* used (normalised)
1551 , [Name] ) -- What is imported but *not* used
1552
1553 warnUnusedImportDecls :: TcGblEnv -> RnM ()
1554 warnUnusedImportDecls gbl_env
1555 = do { uses <- readMutVar (tcg_used_gres gbl_env)
1556 ; let user_imports = filterOut (ideclImplicit . unLoc) (tcg_rn_imports gbl_env)
1557 -- This whole function deals only with *user* imports
1558 -- both for warning about unnecessary ones, and for
1559 -- deciding the minimal ones
1560 rdr_env = tcg_rdr_env gbl_env
1561 fld_env = mkFieldEnv rdr_env
1562
1563 ; let usage :: [ImportDeclUsage]
1564 usage = findImportUsage user_imports uses
1565
1566 ; traceRn (vcat [ text "Uses:" <+> ppr uses
1567 , text "Import usage" <+> ppr usage])
1568 ; whenWOptM Opt_WarnUnusedImports $
1569 mapM_ (warnUnusedImport Opt_WarnUnusedImports fld_env) usage
1570
1571 ; whenGOptM Opt_D_dump_minimal_imports $
1572 printMinimalImports usage }
1573
1574 -- | Warn the user about top level binders that lack type signatures.
1575 warnMissingSignatures :: TcGblEnv -> RnM ()
1576 warnMissingSignatures gbl_env
1577 = do { let exports = availsToNameSet (tcg_exports gbl_env)
1578 sig_ns = tcg_sigs gbl_env
1579 -- We use sig_ns to exclude top-level bindings that are generated by GHC
1580 binds = collectHsBindsBinders $ tcg_binds gbl_env
1581 pat_syns = tcg_patsyns gbl_env
1582
1583 -- Warn about missing signatures
1584 -- Do this only when we we have a type to offer
1585 ; warn_missing_sigs <- woptM Opt_WarnMissingSignatures
1586 ; warn_only_exported <- woptM Opt_WarnMissingExportedSignatures
1587 ; warn_pat_syns <- woptM Opt_WarnMissingPatternSynonymSignatures
1588
1589 ; let add_sig_warns
1590 | warn_only_exported = add_warns Opt_WarnMissingExportedSignatures
1591 | warn_missing_sigs = add_warns Opt_WarnMissingSignatures
1592 | warn_pat_syns = add_warns Opt_WarnMissingPatternSynonymSignatures
1593 | otherwise = return ()
1594
1595 add_warns flag
1596 = when warn_pat_syns
1597 (mapM_ add_pat_syn_warn pat_syns) >>
1598 when (warn_missing_sigs || warn_only_exported)
1599 (mapM_ add_bind_warn binds)
1600 where
1601 add_pat_syn_warn p
1602 = add_warn (patSynName p) (pprPatSynType p)
1603
1604 add_bind_warn id
1605 = do { env <- tcInitTidyEnv -- Why not use emptyTidyEnv?
1606 ; let name = idName id
1607 (_, ty) = tidyOpenType env (idType id)
1608 ty_msg = ppr ty
1609 ; add_warn name ty_msg }
1610
1611 add_warn name ty_msg
1612 = when (name `elemNameSet` sig_ns && export_check name)
1613 (addWarnAt (Reason flag) (getSrcSpan name)
1614 (get_msg name ty_msg))
1615
1616 export_check name
1617 = not warn_only_exported || name `elemNameSet` exports
1618
1619 get_msg name ty_msg
1620 = sep [ text "Top-level binding with no type signature:",
1621 nest 2 $ pprPrefixName name <+> dcolon <+> ty_msg ]
1622
1623 ; add_sig_warns }
1624
1625 {-
1626 Note [The ImportMap]
1627 ~~~~~~~~~~~~~~~~~~~~
1628 The ImportMap is a short-lived intermediate data struture records, for
1629 each import declaration, what stuff brought into scope by that
1630 declaration is actually used in the module.
1631
1632 The SrcLoc is the location of the END of a particular 'import'
1633 declaration. Why *END*? Because we don't want to get confused
1634 by the implicit Prelude import. Consider (Trac #7476) the module
1635 import Foo( foo )
1636 main = print foo
1637 There is an implicit 'import Prelude(print)', and it gets a SrcSpan
1638 of line 1:1 (just the point, not a span). If we use the *START* of
1639 the SrcSpan to identify the import decl, we'll confuse the implicit
1640 import Prelude with the explicit 'import Foo'. So we use the END.
1641 It's just a cheap hack; we could equally well use the Span too.
1642
1643 The AvailInfos are the things imported from that decl (just a list,
1644 not normalised).
1645 -}
1646
1647 type ImportMap = Map SrcLoc [AvailInfo] -- See [The ImportMap]
1648
1649 findImportUsage :: [LImportDecl Name]
1650 -> [GlobalRdrElt]
1651 -> [ImportDeclUsage]
1652
1653 findImportUsage imports used_gres
1654 = map unused_decl imports
1655 where
1656 import_usage :: ImportMap
1657 import_usage
1658 = foldr extendImportMap Map.empty used_gres
1659
1660 unused_decl decl@(L loc (ImportDecl { ideclHiding = imps }))
1661 = (decl, nubAvails used_avails, nameSetElems unused_imps)
1662 where
1663 used_avails = Map.lookup (srcSpanEnd loc) import_usage `orElse` []
1664 -- srcSpanEnd: see Note [The ImportMap]
1665 used_names = availsToNameSetWithSelectors used_avails
1666 used_parents = mkNameSet [n | AvailTC n _ _ <- used_avails]
1667
1668 unused_imps -- Not trivial; see eg Trac #7454
1669 = case imps of
1670 Just (False, L _ imp_ies) ->
1671 foldr (add_unused . unLoc) emptyNameSet imp_ies
1672 _other -> emptyNameSet -- No explicit import list => no unused-name list
1673
1674 add_unused :: IE Name -> NameSet -> NameSet
1675 add_unused (IEVar (L _ n)) acc = add_unused_name n acc
1676 add_unused (IEThingAbs (L _ n)) acc = add_unused_name n acc
1677 add_unused (IEThingAll (L _ n)) acc = add_unused_all n acc
1678 add_unused (IEThingWith (L _ p) wc ns fs) acc =
1679 add_wc_all (add_unused_with p xs acc)
1680 where xs = map unLoc ns ++ map (flSelector . unLoc) fs
1681 add_wc_all = case wc of
1682 NoIEWildcard -> id
1683 IEWildcard _ -> add_unused_all p
1684 add_unused _ acc = acc
1685
1686 add_unused_name n acc
1687 | n `elemNameSet` used_names = acc
1688 | otherwise = acc `extendNameSet` n
1689 add_unused_all n acc
1690 | n `elemNameSet` used_names = acc
1691 | n `elemNameSet` used_parents = acc
1692 | otherwise = acc `extendNameSet` n
1693 add_unused_with p ns acc
1694 | all (`elemNameSet` acc1) ns = add_unused_name p acc1
1695 | otherwise = acc1
1696 where
1697 acc1 = foldr add_unused_name acc ns
1698 -- If you use 'signum' from Num, then the user may well have
1699 -- imported Num(signum). We don't want to complain that
1700 -- Num is not itself mentioned. Hence the two cases in add_unused_with.
1701
1702 extendImportMap :: GlobalRdrElt -> ImportMap -> ImportMap
1703 -- For each of a list of used GREs, find all the import decls that brought
1704 -- it into scope; choose one of them (bestImport), and record
1705 -- the RdrName in that import decl's entry in the ImportMap
1706 extendImportMap gre imp_map
1707 = add_imp gre (bestImport (gre_imp gre)) imp_map
1708 where
1709 add_imp :: GlobalRdrElt -> ImportSpec -> ImportMap -> ImportMap
1710 add_imp gre (ImpSpec { is_decl = imp_decl_spec }) imp_map
1711 = Map.insertWith add decl_loc [avail] imp_map
1712 where
1713 add _ avails = avail : avails -- add is really just a specialised (++)
1714 decl_loc = srcSpanEnd (is_dloc imp_decl_spec)
1715 -- For srcSpanEnd see Note [The ImportMap]
1716 avail = availFromGRE gre
1717
1718 warnUnusedImport :: WarningFlag -> NameEnv (FieldLabelString, Name)
1719 -> ImportDeclUsage -> RnM ()
1720 warnUnusedImport flag fld_env (L loc decl, used, unused)
1721 | Just (False,L _ []) <- ideclHiding decl
1722 = return () -- Do not warn for 'import M()'
1723
1724 | Just (True, L _ hides) <- ideclHiding decl
1725 , not (null hides)
1726 , pRELUDE_NAME == unLoc (ideclName decl)
1727 = return () -- Note [Do not warn about Prelude hiding]
1728 | null used = addWarnAt (Reason flag) loc msg1 -- Nothing used; drop entire decl
1729 | null unused = return () -- Everything imported is used; nop
1730 | otherwise = addWarnAt (Reason flag) loc msg2 -- Some imports are unused
1731 where
1732 msg1 = vcat [pp_herald <+> quotes pp_mod <+> pp_not_used,
1733 nest 2 (text "except perhaps to import instances from"
1734 <+> quotes pp_mod),
1735 text "To import instances alone, use:"
1736 <+> text "import" <+> pp_mod <> parens Outputable.empty ]
1737 msg2 = sep [pp_herald <+> quotes sort_unused,
1738 text "from module" <+> quotes pp_mod <+> pp_not_used]
1739 pp_herald = text "The" <+> pp_qual <+> text "import of"
1740 pp_qual
1741 | ideclQualified decl = text "qualified"
1742 | otherwise = Outputable.empty
1743 pp_mod = ppr (unLoc (ideclName decl))
1744 pp_not_used = text "is redundant"
1745
1746 ppr_possible_field n = case lookupNameEnv fld_env n of
1747 Just (fld, p) -> ppr p <> parens (ppr fld)
1748 Nothing -> ppr n
1749
1750 -- Print unused names in a deterministic (lexicographic) order
1751 sort_unused = pprWithCommas ppr_possible_field $
1752 sortBy (comparing nameOccName) unused
1753
1754 {-
1755 Note [Do not warn about Prelude hiding]
1756 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1757 We do not warn about
1758 import Prelude hiding( x, y )
1759 because even if nothing else from Prelude is used, it may be essential to hide
1760 x,y to avoid name-shadowing warnings. Example (Trac #9061)
1761 import Prelude hiding( log )
1762 f x = log where log = ()
1763
1764
1765
1766 Note [Printing minimal imports]
1767 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1768 To print the minimal imports we walk over the user-supplied import
1769 decls, and simply trim their import lists. NB that
1770
1771 * We do *not* change the 'qualified' or 'as' parts!
1772
1773 * We do not disard a decl altogether; we might need instances
1774 from it. Instead we just trim to an empty import list
1775 -}
1776
1777 printMinimalImports :: [ImportDeclUsage] -> RnM ()
1778 -- See Note [Printing minimal imports]
1779 printMinimalImports imports_w_usage
1780 = do { imports' <- mapM mk_minimal imports_w_usage
1781 ; this_mod <- getModule
1782 ; dflags <- getDynFlags
1783 ; liftIO $
1784 do { h <- openFile (mkFilename dflags this_mod) WriteMode
1785 ; printForUser dflags h neverQualify (vcat (map ppr imports')) }
1786 -- The neverQualify is important. We are printing Names
1787 -- but they are in the context of an 'import' decl, and
1788 -- we never qualify things inside there
1789 -- E.g. import Blag( f, b )
1790 -- not import Blag( Blag.f, Blag.g )!
1791 }
1792 where
1793 mkFilename dflags this_mod
1794 | Just d <- dumpDir dflags = d </> basefn
1795 | otherwise = basefn
1796 where
1797 basefn = moduleNameString (moduleName this_mod) ++ ".imports"
1798
1799 mk_minimal (L l decl, used, unused)
1800 | null unused
1801 , Just (False, _) <- ideclHiding decl
1802 = return (L l decl)
1803 | otherwise
1804 = do { let ImportDecl { ideclName = L _ mod_name
1805 , ideclSource = is_boot
1806 , ideclPkgQual = mb_pkg } = decl
1807 ; iface <- loadSrcInterface doc mod_name is_boot (fmap sl_fs mb_pkg)
1808 ; let lies = map (L l) (concatMap (to_ie iface) used)
1809 ; return (L l (decl { ideclHiding = Just (False, L l lies) })) }
1810 where
1811 doc = text "Compute minimal imports for" <+> ppr decl
1812
1813 to_ie :: ModIface -> AvailInfo -> [IE Name]
1814 -- The main trick here is that if we're importing all the constructors
1815 -- we want to say "T(..)", but if we're importing only a subset we want
1816 -- to say "T(A,B,C)". So we have to find out what the module exports.
1817 to_ie _ (Avail _ n)
1818 = [IEVar (noLoc n)]
1819 to_ie _ (AvailTC n [m] [])
1820 | n==m = [IEThingAbs (noLoc n)]
1821 to_ie iface (AvailTC n ns fs)
1822 = case [(xs,gs) | AvailTC x xs gs <- mi_exports iface
1823 , x == n
1824 , x `elem` xs -- Note [Partial export]
1825 ] of
1826 [xs] | all_used xs -> [IEThingAll (noLoc n)]
1827 | otherwise -> [IEThingWith (noLoc n) NoIEWildcard
1828 (map noLoc (filter (/= n) ns))
1829 (map noLoc fs)]
1830 -- Note [Overloaded field import]
1831 _other | all_non_overloaded fs
1832 -> map (IEVar . noLoc) $ ns ++ map flSelector fs
1833 | otherwise -> [IEThingWith (noLoc n) NoIEWildcard
1834 (map noLoc (filter (/= n) ns)) (map noLoc fs)]
1835 where
1836 fld_lbls = map flLabel fs
1837
1838 all_used (avail_occs, avail_flds)
1839 = all (`elem` ns) avail_occs
1840 && all (`elem` fld_lbls) (map flLabel avail_flds)
1841
1842 all_non_overloaded = all (not . flIsOverloaded)
1843
1844 {-
1845 Note [Partial export]
1846 ~~~~~~~~~~~~~~~~~~~~~
1847 Suppose we have
1848
1849 module A( op ) where
1850 class C a where
1851 op :: a -> a
1852
1853 module B where
1854 import A
1855 f = ..op...
1856
1857 Then the minimal import for module B is
1858 import A( op )
1859 not
1860 import A( C( op ) )
1861 which we would usually generate if C was exported from B. Hence
1862 the (x `elem` xs) test when deciding what to generate.
1863
1864
1865 Note [Overloaded field import]
1866 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1867 On the other hand, if we have
1868
1869 {-# LANGUAGE DuplicateRecordFields #-}
1870 module A where
1871 data T = MkT { foo :: Int }
1872
1873 module B where
1874 import A
1875 f = ...foo...
1876
1877 then the minimal import for module B must be
1878 import A ( T(foo) )
1879 because when DuplicateRecordFields is enabled, field selectors are
1880 not in scope without their enclosing datatype.
1881
1882
1883 ************************************************************************
1884 * *
1885 \subsection{Errors}
1886 * *
1887 ************************************************************************
1888 -}
1889
1890 qualImportItemErr :: RdrName -> SDoc
1891 qualImportItemErr rdr
1892 = hang (text "Illegal qualified name in import item:")
1893 2 (ppr rdr)
1894
1895 badImportItemErrStd :: ModIface -> ImpDeclSpec -> IE RdrName -> SDoc
1896 badImportItemErrStd iface decl_spec ie
1897 = sep [text "Module", quotes (ppr (is_mod decl_spec)), source_import,
1898 text "does not export", quotes (ppr ie)]
1899 where
1900 source_import | mi_boot iface = text "(hi-boot interface)"
1901 | otherwise = Outputable.empty
1902
1903 badImportItemErrDataCon :: OccName -> ModIface -> ImpDeclSpec -> IE RdrName -> SDoc
1904 badImportItemErrDataCon dataType_occ iface decl_spec ie
1905 = vcat [ text "In module"
1906 <+> quotes (ppr (is_mod decl_spec))
1907 <+> source_import <> colon
1908 , nest 2 $ quotes datacon
1909 <+> text "is a data constructor of"
1910 <+> quotes dataType
1911 , text "To import it use"
1912 , nest 2 $ quotes (text "import")
1913 <+> ppr (is_mod decl_spec)
1914 <> parens_sp (dataType <> parens_sp datacon)
1915 , text "or"
1916 , nest 2 $ quotes (text "import")
1917 <+> ppr (is_mod decl_spec)
1918 <> parens_sp (dataType <> text "(..)")
1919 ]
1920 where
1921 datacon_occ = rdrNameOcc $ ieName ie
1922 datacon = parenSymOcc datacon_occ (ppr datacon_occ)
1923 dataType = parenSymOcc dataType_occ (ppr dataType_occ)
1924 source_import | mi_boot iface = text "(hi-boot interface)"
1925 | otherwise = Outputable.empty
1926 parens_sp d = parens (space <> d <> space) -- T( f,g )
1927
1928 badImportItemErr :: ModIface -> ImpDeclSpec -> IE RdrName -> [AvailInfo] -> SDoc
1929 badImportItemErr iface decl_spec ie avails
1930 = case find checkIfDataCon avails of
1931 Just con -> badImportItemErrDataCon (availOccName con) iface decl_spec ie
1932 Nothing -> badImportItemErrStd iface decl_spec ie
1933 where
1934 checkIfDataCon (AvailTC _ ns _) =
1935 case find (\n -> importedFS == nameOccNameFS n) ns of
1936 Just n -> isDataConName n
1937 Nothing -> False
1938 checkIfDataCon _ = False
1939 availOccName = nameOccName . availName
1940 nameOccNameFS = occNameFS . nameOccName
1941 importedFS = occNameFS . rdrNameOcc $ ieName ie
1942
1943 illegalImportItemErr :: SDoc
1944 illegalImportItemErr = text "Illegal import item"
1945
1946 dodgyImportWarn :: RdrName -> SDoc
1947 dodgyImportWarn item = dodgyMsg (text "import") item
1948 dodgyExportWarn :: Name -> SDoc
1949 dodgyExportWarn item = dodgyMsg (text "export") item
1950
1951 dodgyMsg :: (OutputableBndr n, HasOccName n) => SDoc -> n -> SDoc
1952 dodgyMsg kind tc
1953 = sep [ text "The" <+> kind <+> ptext (sLit "item")
1954 <+> quotes (ppr (IEThingAll (noLoc tc)))
1955 <+> text "suggests that",
1956 quotes (ppr tc) <+> text "has (in-scope) constructors or class methods,",
1957 text "but it has none" ]
1958
1959 exportItemErr :: IE RdrName -> SDoc
1960 exportItemErr export_item
1961 = sep [ text "The export item" <+> quotes (ppr export_item),
1962 text "attempts to export constructors or class methods that are not visible here" ]
1963
1964 exportClashErr :: GlobalRdrEnv -> Name -> Name -> IE RdrName -> IE RdrName
1965 -> MsgDoc
1966 exportClashErr global_env name1 name2 ie1 ie2
1967 = vcat [ text "Conflicting exports for" <+> quotes (ppr occ) <> colon
1968 , ppr_export ie1' name1'
1969 , ppr_export ie2' name2' ]
1970 where
1971 occ = nameOccName name1
1972 ppr_export ie name = nest 3 (hang (quotes (ppr ie) <+> text "exports" <+>
1973 quotes (ppr name))
1974 2 (pprNameProvenance (get_gre name)))
1975
1976 -- get_gre finds a GRE for the Name, so that we can show its provenance
1977 get_gre name
1978 = case lookupGRE_Name global_env name of
1979 (gre:_) -> gre
1980 [] -> pprPanic "exportClashErr" (ppr name)
1981 get_loc name = greSrcSpan (get_gre name)
1982 (name1', ie1', name2', ie2') = if get_loc name1 < get_loc name2
1983 then (name1, ie1, name2, ie2)
1984 else (name2, ie2, name1, ie1)
1985
1986 addDupDeclErr :: [GlobalRdrElt] -> TcRn ()
1987 addDupDeclErr [] = panic "addDupDeclErr: empty list"
1988 addDupDeclErr gres@(gre : _)
1989 = addErrAt (getSrcSpan (last sorted_names)) $
1990 -- Report the error at the later location
1991 vcat [text "Multiple declarations of" <+>
1992 quotes (ppr (nameOccName name)),
1993 -- NB. print the OccName, not the Name, because the
1994 -- latter might not be in scope in the RdrEnv and so will
1995 -- be printed qualified.
1996 text "Declared at:" <+>
1997 vcat (map (ppr . nameSrcLoc) sorted_names)]
1998 where
1999 name = gre_name gre
2000 sorted_names = sortWith nameSrcLoc (map gre_name gres)
2001
2002 dupExportWarn :: OccName -> IE RdrName -> IE RdrName -> SDoc
2003 dupExportWarn occ_name ie1 ie2
2004 = hsep [quotes (ppr occ_name),
2005 text "is exported by", quotes (ppr ie1),
2006 text "and", quotes (ppr ie2)]
2007
2008 dupModuleExport :: ModuleName -> SDoc
2009 dupModuleExport mod
2010 = hsep [text "Duplicate",
2011 quotes (text "Module" <+> ppr mod),
2012 text "in export list"]
2013
2014 moduleNotImported :: ModuleName -> SDoc
2015 moduleNotImported mod
2016 = text "The export item `module" <+> ppr mod <>
2017 text "' is not imported"
2018
2019 nullModuleExport :: ModuleName -> SDoc
2020 nullModuleExport mod
2021 = text "The export item `module" <+> ppr mod <> ptext (sLit "' exports nothing")
2022
2023 missingImportListWarn :: ModuleName -> SDoc
2024 missingImportListWarn mod
2025 = text "The module" <+> quotes (ppr mod) <+> ptext (sLit "does not have an explicit import list")
2026
2027 missingImportListItem :: IE RdrName -> SDoc
2028 missingImportListItem ie
2029 = text "The import item" <+> quotes (ppr ie) <+> ptext (sLit "does not have an explicit import list")
2030
2031 moduleWarn :: ModuleName -> WarningTxt -> SDoc
2032 moduleWarn mod (WarningTxt _ txt)
2033 = sep [ text "Module" <+> quotes (ppr mod) <> ptext (sLit ":"),
2034 nest 2 (vcat (map (ppr . sl_fs . unLoc) txt)) ]
2035 moduleWarn mod (DeprecatedTxt _ txt)
2036 = sep [ text "Module" <+> quotes (ppr mod)
2037 <+> text "is deprecated:",
2038 nest 2 (vcat (map (ppr . sl_fs . unLoc) txt)) ]
2039
2040 packageImportErr :: SDoc
2041 packageImportErr
2042 = text "Package-qualified imports are not enabled; use PackageImports"
2043
2044 -- This data decl will parse OK
2045 -- data T = a Int
2046 -- treating "a" as the constructor.
2047 -- It is really hard to make the parser spot this malformation.
2048 -- So the renamer has to check that the constructor is legal
2049 --
2050 -- We can get an operator as the constructor, even in the prefix form:
2051 -- data T = :% Int Int
2052 -- from interface files, which always print in prefix form
2053
2054 checkConName :: RdrName -> TcRn ()
2055 checkConName name = checkErr (isRdrDataCon name) (badDataCon name)
2056
2057 badDataCon :: RdrName -> SDoc
2058 badDataCon name
2059 = hsep [text "Illegal data constructor name", quotes (ppr name)]