2 % (c) The University of Glasgow, 2000
4 \section[HscTypes]{Types for the per-module compiler}
10 ModuleLocation(..), showModMsg,
12 ModDetails(..), ModIface(..),
13 HomeSymbolTable, emptySymbolTable,
15 HomeIfaceTable, PackageIfaceTable, emptyIfaceTable,
16 lookupIface, lookupIfaceByModName, moduleNameToModule,
19 InteractiveContext(..),
21 IfaceDecls, mkIfaceDecls, dcl_tycl, dcl_rules, dcl_insts,
23 VersionInfo(..), initialVersionInfo, lookupVersion,
24 FixityEnv, lookupFixity, collectFixities,
26 TyThing(..), isTyClThing, implicitTyThingIds,
28 TypeEnv, lookupType, mkTypeEnv, emptyTypeEnv,
29 extendTypeEnvList, extendTypeEnvWithIds,
30 typeEnvElts, typeEnvClasses, typeEnvTyCons, typeEnvIds,
32 ImportedModuleInfo, WhetherHasOrphans, ImportVersion, WhatsImported(..),
33 PersistentRenamerState(..), IsBootInterface, DeclsMap,
34 IfaceInsts, IfaceRules, GatedDecl, GatedDecls, GateFn, IsExported,
35 NameSupply(..), OrigNameCache, OrigIParamCache,
36 Avails, AvailEnv, emptyAvailEnv,
37 GenAvailInfo(..), AvailInfo, RdrAvailInfo,
38 ExportItem, RdrExportItem,
39 PersistentCompilerState(..),
41 Deprecations(..), lookupDeprec,
43 InstEnv, ClsInstEnv, DFunId,
44 PackageInstEnv, PackageRuleBase,
46 GlobalRdrEnv, GlobalRdrElt(..), pprGlobalRdrEnv,
47 LocalRdrEnv, extendLocalRdrEnv,
51 Provenance(..), ImportReason(..),
52 pprNameProvenance, hasBetterProv
56 #include "HsVersions.h"
58 import RdrName ( RdrName, RdrNameEnv, addListToRdrEnv,
59 mkRdrUnqual, rdrEnvToList )
60 import Name ( Name, NamedThing, getName, nameOccName, nameModule, nameSrcLoc )
62 import OccName ( OccName )
64 import InstEnv ( InstEnv, ClsInstEnv, DFunId )
65 import Rules ( RuleBase )
66 import CoreSyn ( CoreBind )
68 import Class ( Class, classSelIds )
69 import TyCon ( TyCon, isNewTyCon, tyConGenIds, tyConSelIds, tyConDataCons_maybe )
70 import DataCon ( dataConWorkId, dataConWrapId )
72 import BasicTypes ( Version, initialVersion, Fixity, defaultFixity, IPName )
74 import HsSyn ( DeprecTxt, TyClDecl, tyClDeclName, ifaceRuleDeclName,
76 import RdrHsSyn ( RdrNameInstDecl, RdrNameRuleDecl, RdrNameTyClDecl )
77 import RnHsSyn ( RenamedTyClDecl, RenamedRuleDecl, RenamedInstDecl )
79 import CoreSyn ( IdCoreRule )
83 import Maybes ( seqMaybe, orElse, expectJust )
85 import SrcLoc ( SrcLoc, isGoodSrcLoc )
86 import Util ( thenCmp, sortLt )
87 import UniqSupply ( UniqSupply )
88 import Maybe ( fromJust )
91 %************************************************************************
93 \subsection{Which mode we're in
95 %************************************************************************
98 data GhciMode = Batch | Interactive | OneShot
103 %************************************************************************
105 \subsection{Module locations}
107 %************************************************************************
112 ml_hs_file :: Maybe FilePath,
113 ml_hspp_file :: Maybe FilePath, -- path of preprocessed source
114 ml_hi_file :: FilePath,
115 ml_obj_file :: Maybe FilePath
119 instance Outputable ModuleLocation where
122 -- Probably doesn't really belong here, but used in HscMain and InteractiveUI.
124 showModMsg :: Bool -> Module -> ModuleLocation -> String
125 showModMsg use_object mod location =
126 mod_str ++ replicate (max 0 (16 - length mod_str)) ' '
127 ++" ( " ++ expectJust "showModMsg" (ml_hs_file location) ++ ", "
129 then expectJust "showModMsg" (ml_obj_file location)
132 where mod_str = moduleUserString mod
135 For a module in another package, the hs_file and obj_file
136 components of ModuleLocation are undefined.
138 The locations specified by a ModuleLocation may or may not
139 correspond to actual files yet: for example, even if the object
140 file doesn't exist, the ModuleLocation still contains the path to
141 where the object file will reside if/when it is created.
144 %************************************************************************
146 \subsection{Symbol tables and Module details}
148 %************************************************************************
150 A @ModIface@ plus a @ModDetails@ summarises everything we know
151 about a compiled module. The @ModIface@ is the stuff *before* linking,
152 and can be written out to an interface file. (The @ModDetails@ is after
153 linking; it is the "linked" form of the mi_decls field.)
155 When we *read* an interface file, we also construct a @ModIface@ from it,
156 except that the mi_decls part is empty; when reading we consolidate
157 the declarations into a single indexed map in the @PersistentRenamerState@.
162 mi_module :: !Module,
163 mi_package :: !PackageName, -- Which package the module comes from
164 mi_version :: !VersionInfo, -- Module version number
166 mi_orphan :: WhetherHasOrphans, -- Whether this module has orphans
167 -- NOT STRICT! we fill this field with _|_ sometimes
169 mi_boot :: !IsBootInterface, -- read from an hi-boot file?
171 mi_usages :: [ImportVersion Name],
172 -- Usages; kept sorted so that it's easy to decide
173 -- whether to write a new iface file (changing usages
174 -- doesn't affect the version of this module)
175 -- NOT STRICT! we read this field lazilly from the interface file
177 mi_exports :: ![ExportItem],
178 -- What it exports Kept sorted by (mod,occ), to make
179 -- version comparisons easier
181 mi_globals :: !(Maybe GlobalRdrEnv),
182 -- Its top level environment or Nothing if we read this
183 -- interface from a file.
185 mi_fixities :: !FixityEnv, -- Fixities
186 mi_deprecs :: Deprecations, -- Deprecations
187 -- NOT STRICT! we read this field lazilly from the interface file
189 mi_decls :: IfaceDecls -- The RnDecls form of ModDetails
190 -- NOT STRICT! we fill this field with _|_ sometimes
193 data IfaceDecls = IfaceDecls { dcl_tycl :: [RenamedTyClDecl], -- Sorted
194 dcl_rules :: [RenamedRuleDecl], -- Sorted
195 dcl_insts :: [RenamedInstDecl] } -- Unsorted
197 mkIfaceDecls :: [RenamedTyClDecl] -> [RenamedRuleDecl] -> [RenamedInstDecl] -> IfaceDecls
198 mkIfaceDecls tycls rules insts
199 = IfaceDecls { dcl_tycl = sortLt lt_tycl tycls,
200 dcl_rules = sortLt lt_rule rules,
203 d1 `lt_tycl` d2 = tyClDeclName d1 < tyClDeclName d2
204 r1 `lt_rule` r2 = ifaceRuleDeclName r1 < ifaceRuleDeclName r2
207 -- typechecker should only look at this, not ModIface
208 -- Should be able to construct ModDetails from mi_decls in ModIface
211 -- The next three fields are created by the typechecker
212 md_types :: !TypeEnv,
213 md_insts :: ![DFunId], -- Dfun-ids for the instances in this module
214 md_rules :: ![IdCoreRule], -- Domain may include Ids from other modules
215 md_binds :: ![CoreBind]
218 -- The ModDetails takes on several slightly different forms:
220 -- After typecheck + desugar
221 -- md_types Contains TyCons, Classes, and implicit Ids
222 -- md_insts All instances from this module (incl derived ones)
223 -- md_rules All rules from this module
224 -- md_binds Desugared bindings
226 -- After simplification
227 -- md_types Same as after typecheck
229 -- md_rules Orphan rules only (local ones now attached to binds)
230 -- md_binds With rules attached
233 -- md_types Now contains Ids as well, replete with final IdInfo
234 -- The Ids are only the ones that are visible from
235 -- importing modules. Without -O that means only
236 -- exported Ids, but with -O importing modules may
237 -- see ids mentioned in unfoldings of exported Ids
239 -- md_insts Same DFunIds as before, but with final IdInfo,
240 -- and the unique might have changed; remember that
241 -- CoreTidy links up the uniques of old and new versions
243 -- md_rules All rules for exported things, substituted with final Ids
247 -- Passed back to compilation manager
248 -- Just as after CoreTidy, but with md_binds nuked
253 emptyModIface :: Module -> ModIface
255 = ModIface { mi_module = mod,
256 mi_package = preludePackage, -- XXX fully bogus
257 mi_version = initialVersionInfo,
262 mi_fixities = emptyNameEnv,
263 mi_globals = Nothing,
264 mi_deprecs = NoDeprecs,
265 mi_decls = panic "emptyModIface: decls"
269 Symbol tables map modules to ModDetails:
272 type SymbolTable = ModuleEnv ModDetails
273 type IfaceTable = ModuleEnv ModIface
275 type HomeIfaceTable = IfaceTable
276 type PackageIfaceTable = IfaceTable
278 type HomeSymbolTable = SymbolTable -- Domain = modules in the home package
280 emptySymbolTable :: SymbolTable
281 emptySymbolTable = emptyModuleEnv
283 emptyIfaceTable :: IfaceTable
284 emptyIfaceTable = emptyModuleEnv
287 Simple lookups in the symbol table.
290 lookupIface :: HomeIfaceTable -> PackageIfaceTable -> Name -> Maybe ModIface
291 -- We often have two IfaceTables, and want to do a lookup
292 lookupIface hit pit name
293 = lookupModuleEnv hit mod `seqMaybe` lookupModuleEnv pit mod
295 mod = nameModule name
297 lookupIfaceByModName :: HomeIfaceTable -> PackageIfaceTable -> ModuleName -> Maybe ModIface
298 -- We often have two IfaceTables, and want to do a lookup
299 lookupIfaceByModName hit pit mod
300 = lookupModuleEnvByName hit mod `seqMaybe` lookupModuleEnvByName pit mod
302 -- Use instead of Finder.findModule if possible: this way doesn't
303 -- require filesystem operations, and it is guaranteed not to fail
304 -- when the IfaceTables are properly populated (i.e. after the renamer).
305 moduleNameToModule :: HomeIfaceTable -> PackageIfaceTable -> ModuleName
307 moduleNameToModule hit pit mod
308 = mi_module (fromJust (lookupIfaceByModName hit pit mod))
312 %************************************************************************
314 \subsection{The interactive context}
316 %************************************************************************
319 data InteractiveContext
320 = InteractiveContext {
321 ic_toplev_scope :: [Module], -- Include the "top-level" scope of
324 ic_exports :: [Module], -- Include just the exports of these
327 ic_rn_gbl_env :: GlobalRdrEnv, -- The cached GlobalRdrEnv, built from
328 -- ic_toplev_scope and ic_exports
330 ic_print_unqual :: PrintUnqualified,
331 -- cached PrintUnqualified, as above
333 ic_rn_local_env :: LocalRdrEnv, -- Lexical context for variables bound
334 -- during interaction
336 ic_type_env :: TypeEnv -- Ditto for types
341 %************************************************************************
343 \subsection{Type environment stuff}
345 %************************************************************************
348 data TyThing = AnId Id
352 isTyClThing :: TyThing -> Bool
353 isTyClThing (ATyCon _) = True
354 isTyClThing (AClass _) = True
355 isTyClThing (AnId _) = False
357 instance NamedThing TyThing where
358 getName (AnId id) = getName id
359 getName (ATyCon tc) = getName tc
360 getName (AClass cl) = getName cl
362 instance Outputable TyThing where
363 ppr (AnId id) = ptext SLIT("AnId") <+> ppr id
364 ppr (ATyCon tc) = ptext SLIT("ATyCon") <+> ppr tc
365 ppr (AClass cl) = ptext SLIT("AClass") <+> ppr cl
368 typeEnvElts :: TypeEnv -> [TyThing]
369 typeEnvClasses :: TypeEnv -> [Class]
370 typeEnvTyCons :: TypeEnv -> [TyCon]
371 typeEnvIds :: TypeEnv -> [Id]
373 typeEnvElts env = nameEnvElts env
374 typeEnvClasses env = [cl | AClass cl <- typeEnvElts env]
375 typeEnvTyCons env = [tc | ATyCon tc <- typeEnvElts env]
376 typeEnvIds env = [id | AnId id <- typeEnvElts env]
378 implicitTyThingIds :: [TyThing] -> [Id]
379 -- Add the implicit data cons and selectors etc
380 implicitTyThingIds things
381 = concat (map go things)
384 go (AClass cl) = classSelIds cl
385 go (ATyCon tc) = tyConGenIds tc ++
387 [ n | dc <- tyConDataCons_maybe tc `orElse` [],
388 n <- implicitConIds tc dc]
389 -- Synonyms return empty list of constructors and selectors
391 implicitConIds tc dc -- Newtypes have a constructor wrapper,
393 | isNewTyCon tc = [dataConWrapId dc]
394 | otherwise = [dataConWorkId dc, dataConWrapId dc]
399 type TypeEnv = NameEnv TyThing
401 emptyTypeEnv = emptyNameEnv
403 mkTypeEnv :: [TyThing] -> TypeEnv
404 mkTypeEnv things = extendTypeEnvList emptyTypeEnv things
406 extendTypeEnvList :: TypeEnv -> [TyThing] -> TypeEnv
407 extendTypeEnvList env things
408 = extendNameEnvList env [(getName thing, thing) | thing <- things]
410 extendTypeEnvWithIds :: TypeEnv -> [Id] -> TypeEnv
411 extendTypeEnvWithIds env ids
412 = extendNameEnvList env [(getName id, AnId id) | id <- ids]
416 lookupType :: HomeSymbolTable -> PackageTypeEnv -> Name -> Maybe TyThing
417 lookupType hst pte name
418 = case lookupModuleEnv hst (nameModule name) of
419 Just details -> lookupNameEnv (md_types details) name
420 Nothing -> lookupNameEnv pte name
423 %************************************************************************
425 \subsection{Auxiliary types}
427 %************************************************************************
429 These types are defined here because they are mentioned in ModDetails,
430 but they are mostly elaborated elsewhere
435 vers_module :: Version, -- Changes when anything changes
436 vers_exports :: Version, -- Changes when export list changes
437 vers_rules :: Version, -- Changes when any rule changes
438 vers_decls :: NameEnv Version
439 -- Versions for "big" names only (not data constructors, class ops)
440 -- The version of an Id changes if its fixity changes
441 -- Ditto data constructors, class operations, except that the version of
442 -- the parent class/tycon changes
444 -- If a name isn't in the map, it means 'initialVersion'
447 initialVersionInfo :: VersionInfo
448 initialVersionInfo = VersionInfo { vers_module = initialVersion,
449 vers_exports = initialVersion,
450 vers_rules = initialVersion,
451 vers_decls = emptyNameEnv
454 lookupVersion :: NameEnv Version -> Name -> Version
455 lookupVersion env name = lookupNameEnv env name `orElse` initialVersion
457 data Deprecations = NoDeprecs
458 | DeprecAll DeprecTxt -- Whole module deprecated
459 | DeprecSome (NameEnv (Name,DeprecTxt)) -- Some things deprecated
461 -- We keep the Name in the range, so we can print them out
463 lookupDeprec :: Deprecations -> Name -> Maybe DeprecTxt
464 lookupDeprec NoDeprecs name = Nothing
465 lookupDeprec (DeprecAll txt) name = Just txt
466 lookupDeprec (DeprecSome env) name = case lookupNameEnv env name of
467 Just (_, txt) -> Just txt
470 instance Eq Deprecations where
471 -- Used when checking whether we need write a new interface
472 NoDeprecs == NoDeprecs = True
473 (DeprecAll t1) == (DeprecAll t2) = t1 == t2
474 (DeprecSome e1) == (DeprecSome e2) = nameEnvElts e1 == nameEnvElts e2
480 type Avails = [AvailInfo]
481 type AvailInfo = GenAvailInfo Name
482 type RdrAvailInfo = GenAvailInfo OccName
484 data GenAvailInfo name = Avail name -- An ordinary identifier
485 | AvailTC name -- The name of the type or class
486 [name] -- The available pieces of type/class.
487 -- NB: If the type or class is itself
488 -- to be in scope, it must be in this list.
489 -- Thus, typically: AvailTC Eq [Eq, ==, /=]
491 -- Equality used when deciding if the interface has changed
493 type RdrExportItem = (ModuleName, [RdrAvailInfo])
494 type ExportItem = (ModuleName, [AvailInfo])
496 type AvailEnv = NameEnv AvailInfo -- Maps a Name to the AvailInfo that contains it
498 emptyAvailEnv :: AvailEnv
499 emptyAvailEnv = emptyNameEnv
501 instance Outputable n => Outputable (GenAvailInfo n) where
504 pprAvail :: Outputable n => GenAvailInfo n -> SDoc
505 pprAvail (AvailTC n ns) = ppr n <> case {- filter (/= n) -} ns of
507 ns' -> braces (hsep (punctuate comma (map ppr ns')))
509 pprAvail (Avail n) = ppr n
513 type FixityEnv = NameEnv Fixity
515 lookupFixity :: FixityEnv -> Name -> Fixity
516 lookupFixity env n = lookupNameEnv env n `orElse` defaultFixity
518 collectFixities :: FixityEnv -> [TyClDecl Name pat] -> [(Name,Fixity)]
519 collectFixities env decls
521 | d <- decls, (n,_) <- tyClDeclNames d,
522 Just fix <- [lookupNameEnv env n]
527 %************************************************************************
529 \subsection{WhatsImported}
531 %************************************************************************
534 type WhetherHasOrphans = Bool
536 -- * an instance decl in a module other than the defn module for
537 -- one of the tycons or classes in the instance head
538 -- * a transformation rule in a module other than the one defining
539 -- the function in the head of the rule.
541 type IsBootInterface = Bool
543 type ImportVersion name = (ModuleName, WhetherHasOrphans, IsBootInterface, WhatsImported name)
545 data WhatsImported name = NothingAtAll -- The module is below us in the
546 -- hierarchy, but we import nothing
548 | Everything Version -- Used for modules from other packages;
549 -- we record only the module's version number
552 Version -- Module version
553 (Maybe Version) -- Export-list version, if we depend on it
554 [(name,Version)] -- List guaranteed non-empty
555 Version -- Rules version
558 -- 'Specifically' doesn't let you say "I imported f but none of the rules in
559 -- the module". If you use anything in the module you get its rule version
560 -- So if the rules change, you'll recompile, even if you don't use them.
561 -- This is easy to implement, and it's safer: you might not have used the rules last
562 -- time round, but if someone has added a new rule you might need it this time
564 -- The export list field is (Just v) if we depend on the export list:
565 -- we imported the module without saying exactly what we imported
566 -- We need to recompile if the module exports changes, because we might
567 -- now have a name clash in the importing module.
569 type IsExported = Name -> Bool -- True for names that are exported from this module
573 %************************************************************************
575 \subsection{The persistent compiler state}
577 %************************************************************************
579 The @PersistentCompilerState@ persists across successive calls to the
582 * A ModIface for each non-home-package module
584 * An accumulated TypeEnv from all the modules in imported packages
586 * An accumulated InstEnv from all the modules in imported packages
587 The point is that we don't want to keep recreating it whenever
588 we compile a new module. The InstEnv component of pcPST is empty.
589 (This means we might "see" instances that we shouldn't "really" see;
590 but the Haskell Report is vague on what is meant to be visible,
591 so we just take the easy road here.)
595 * The persistent renamer state
598 data PersistentCompilerState
600 pcs_PIT :: !PackageIfaceTable, -- Domain = non-home-package modules
601 -- the mi_decls component is empty
603 pcs_PTE :: !PackageTypeEnv, -- Domain = non-home-package modules
604 -- except that the InstEnv components is empty
606 pcs_insts :: !PackageInstEnv, -- The total InstEnv accumulated from all
607 -- the non-home-package modules
609 pcs_rules :: !PackageRuleBase, -- Ditto RuleEnv
611 pcs_PRS :: !PersistentRenamerState
616 The persistent renamer state contains:
618 * A name supply, which deals with allocating unique names to
619 (Module,OccName) original names,
621 * A "holding pen" for declarations that have been read out of
622 interface files but not yet sucked in, renamed, and typechecked
625 type PackageTypeEnv = TypeEnv
626 type PackageRuleBase = RuleBase
627 type PackageInstEnv = InstEnv
629 data PersistentRenamerState
630 = PRS { prsOrig :: !NameSupply,
631 prsImpMods :: !ImportedModuleInfo,
633 -- Holding pens for stuff that has been read in
634 -- but not yet slurped into the renamer
635 prsDecls :: !DeclsMap,
636 prsInsts :: !IfaceInsts,
637 prsRules :: !IfaceRules
641 The NameSupply makes sure that there is just one Unique assigned for
642 each original name; i.e. (module-name, occ-name) pair. The Name is
643 always stored as a Global, and has the SrcLoc of its binding location.
644 Actually that's not quite right. When we first encounter the original
645 name, we might not be at its binding site (e.g. we are reading an
646 interface file); so we give it 'noSrcLoc' then. Later, when we find
647 its binding site, we fix it up.
649 Exactly the same is true of the Module stored in the Name. When we first
650 encounter the occurrence, we may not know the details of the module, so
651 we just store junk. Then when we find the binding site, we fix it up.
655 = NameSupply { nsUniqs :: UniqSupply,
657 nsNames :: OrigNameCache,
658 -- Ensures that one original name gets one unique
659 nsIPs :: OrigIParamCache
660 -- Ensures that one implicit parameter name gets one unique
663 type OrigNameCache = FiniteMap (ModuleName,OccName) Name
664 type OrigIParamCache = FiniteMap (IPName RdrName) (IPName Name)
667 @ImportedModuleInfo@ contains info ONLY about modules that have not yet
668 been loaded into the iPIT. These modules are mentioned in interfaces we've
669 already read, so we know a tiny bit about them, but we havn't yet looked
670 at the interface file for the module itself. It needs to persist across
671 invocations of the renamer, at least from Rename.checkOldIface to Rename.renameSource.
672 And there's no harm in it persisting across multiple compilations.
675 type ImportedModuleInfo = FiniteMap ModuleName (WhetherHasOrphans, IsBootInterface)
678 A DeclsMap contains a binding for each Name in the declaration
679 including the constructors of a type decl etc. The Bool is True just
683 type DeclsMap = (NameEnv (AvailInfo, Bool, (Module, RdrNameTyClDecl)), Int)
684 -- The Int says how many have been sucked in
686 type IfaceInsts = GatedDecls RdrNameInstDecl
687 type IfaceRules = GatedDecls RdrNameRuleDecl
689 type GatedDecls d = (Bag (GatedDecl d), Int) -- The Int says how many have been sucked in
690 type GatedDecl d = (GateFn, (Module, d))
691 type GateFn = (Name -> Bool) -> Bool -- Returns True <=> gate is open
692 -- The (Name -> Bool) fn returns True for visible Names
693 -- For example, suppose this is in an interface file
694 -- instance C T where ...
695 -- We want to slurp this decl if both C and T are "visible" in
696 -- the importing module. See "The gating story" in RnIfaces for details.
700 %************************************************************************
702 \subsection{Provenance and export info}
704 %************************************************************************
706 A LocalRdrEnv is used for local bindings (let, where, lambda, case)
709 type LocalRdrEnv = RdrNameEnv Name
711 extendLocalRdrEnv :: LocalRdrEnv -> [Name] -> LocalRdrEnv
712 extendLocalRdrEnv env names
713 = addListToRdrEnv env [(mkRdrUnqual (nameOccName n), n) | n <- names]
716 The GlobalRdrEnv gives maps RdrNames to Names. There is a separate
717 one for each module, corresponding to that module's top-level scope.
720 type GlobalRdrEnv = RdrNameEnv [GlobalRdrElt]
721 -- The list is because there may be name clashes
722 -- These only get reported on lookup, not on construction
724 data GlobalRdrElt = GRE Name Provenance (Maybe DeprecTxt)
725 -- The Maybe DeprecTxt tells whether this name is deprecated
728 = vcat (map pp (rdrEnvToList env))
730 pp (rn, nps) = ppr rn <> colon <+>
731 vcat [ppr n <+> pprNameProvenance n p | (GRE n p _) <- nps]
734 The "provenance" of something says how it came to be in scope.
738 = LocalDef -- Defined locally
740 | NonLocalDef -- Defined non-locally
743 -- Just used for grouping error messages (in RnEnv.warnUnusedBinds)
744 instance Eq Provenance where
745 p1 == p2 = case p1 `compare` p2 of EQ -> True; _ -> False
747 instance Eq ImportReason where
748 p1 == p2 = case p1 `compare` p2 of EQ -> True; _ -> False
750 instance Ord Provenance where
751 compare LocalDef LocalDef = EQ
752 compare LocalDef (NonLocalDef _) = LT
753 compare (NonLocalDef _) LocalDef = GT
755 compare (NonLocalDef reason1) (NonLocalDef reason2)
756 = compare reason1 reason2
758 instance Ord ImportReason where
759 compare ImplicitImport ImplicitImport = EQ
760 compare ImplicitImport (UserImport _ _ _) = LT
761 compare (UserImport _ _ _) ImplicitImport = GT
762 compare (UserImport m1 loc1 _) (UserImport m2 loc2 _)
763 = (m1 `compare` m2) `thenCmp` (loc1 `compare` loc2)
767 = UserImport Module SrcLoc Bool -- Imported from module M on line L
768 -- Note the M may well not be the defining module
770 -- The Bool is true iff the thing was named *explicitly* in the import spec,
771 -- rather than being imported as part of a group; e.g.
774 -- Here, everything imported by B, and the constructors of T
775 -- are not named explicitly; only T is named explicitly.
776 -- This info is used when warning of unused names.
778 | ImplicitImport -- Imported implicitly for some other reason
782 hasBetterProv :: Provenance -> Provenance -> Bool
784 -- a local thing over an imported thing
785 -- a user-imported thing over a non-user-imported thing
786 -- an explicitly-imported thing over an implicitly imported thing
787 hasBetterProv LocalDef _ = True
788 hasBetterProv (NonLocalDef (UserImport _ _ _ )) (NonLocalDef ImplicitImport) = True
789 hasBetterProv _ _ = False
791 pprNameProvenance :: Name -> Provenance -> SDoc
792 pprNameProvenance name LocalDef = ptext SLIT("defined at") <+> ppr (nameSrcLoc name)
793 pprNameProvenance name (NonLocalDef why) = sep [ppr_reason why,
794 nest 2 (ppr_defn (nameSrcLoc name))]
796 ppr_reason ImplicitImport = ptext SLIT("implicitly imported")
797 ppr_reason (UserImport mod loc _) = ptext SLIT("imported from") <+> ppr mod <+> ptext SLIT("at") <+> ppr loc
799 ppr_defn loc | isGoodSrcLoc loc = parens (ptext SLIT("at") <+> ppr loc)