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,
19 InteractiveContext(..),
21 IfaceDecls, mkIfaceDecls, dcl_tycl, dcl_rules, dcl_insts,
23 VersionInfo(..), initialVersionInfo, lookupVersion,
25 TyThing(..), isTyClThing, implicitTyThingIds,
27 TypeEnv, lookupType, mkTypeEnv, emptyTypeEnv,
28 extendTypeEnvList, extendTypeEnvWithIds,
29 typeEnvElts, typeEnvClasses, typeEnvTyCons, typeEnvIds,
31 ImportedModuleInfo, WhetherHasOrphans, ImportVersion, WhatsImported(..),
32 PersistentRenamerState(..), IsBootInterface, DeclsMap,
33 IfaceInsts, IfaceRules, GatedDecl, GatedDecls, GateFn, IsExported,
34 NameSupply(..), OrigNameCache, OrigIParamCache,
35 Avails, AvailEnv, emptyAvailEnv,
36 GenAvailInfo(..), AvailInfo, RdrAvailInfo,
37 PersistentCompilerState(..),
39 Deprecations(..), lookupDeprec,
41 InstEnv, ClsInstEnv, DFunId,
42 PackageInstEnv, PackageRuleBase,
44 GlobalRdrEnv, GlobalRdrElt(..), pprGlobalRdrEnv,
45 LocalRdrEnv, extendLocalRdrEnv,
49 Provenance(..), ImportReason(..),
50 pprNameProvenance, hasBetterProv
54 #include "HsVersions.h"
56 import RdrName ( RdrName, RdrNameEnv, addListToRdrEnv, emptyRdrEnv,
57 mkRdrUnqual, rdrEnvToList )
58 import Name ( Name, NamedThing, getName, nameOccName, nameModule, nameSrcLoc )
60 import OccName ( OccName )
62 import InstEnv ( InstEnv, ClsInstEnv, DFunId )
63 import Rules ( RuleBase )
64 import CoreSyn ( CoreBind )
66 import Class ( Class, classSelIds )
67 import TyCon ( TyCon, isNewTyCon, tyConGenIds, tyConSelIds, tyConDataConsIfAvailable )
68 import DataCon ( dataConId, dataConWrapId )
70 import BasicTypes ( Version, initialVersion, Fixity, IPName )
72 import HsSyn ( DeprecTxt, tyClDeclName, ifaceRuleDeclName )
73 import RdrHsSyn ( RdrNameInstDecl, RdrNameRuleDecl, RdrNameTyClDecl )
74 import RnHsSyn ( RenamedTyClDecl, RenamedRuleDecl, RenamedInstDecl )
76 import CoreSyn ( IdCoreRule )
78 import FiniteMap ( FiniteMap )
80 import Maybes ( seqMaybe, orElse )
82 import SrcLoc ( SrcLoc, isGoodSrcLoc )
83 import Util ( thenCmp, sortLt, unJust )
84 import UniqSupply ( UniqSupply )
87 %************************************************************************
89 \subsection{Which mode we're in
91 %************************************************************************
94 data GhciMode = Batch | Interactive | OneShot
99 %************************************************************************
101 \subsection{Module locations}
103 %************************************************************************
108 ml_hs_file :: Maybe FilePath,
109 ml_hspp_file :: Maybe FilePath, -- path of preprocessed source
110 ml_hi_file :: FilePath,
111 ml_obj_file :: Maybe FilePath
115 instance Outputable ModuleLocation where
118 -- Probably doesn't really belong here, but used in HscMain and InteractiveUI.
120 showModMsg :: Bool -> Module -> ModuleLocation -> String
121 showModMsg use_object mod location =
122 mod_str ++ replicate (max 0 (16 - length mod_str)) ' '
123 ++" ( " ++ unJust "showModMsg" (ml_hs_file location) ++ ", "
125 then unJust "showModMsg" (ml_obj_file location)
128 where mod_str = moduleUserString mod
131 For a module in another package, the hs_file and obj_file
132 components of ModuleLocation are undefined.
134 The locations specified by a ModuleLocation may or may not
135 correspond to actual files yet: for example, even if the object
136 file doesn't exist, the ModuleLocation still contains the path to
137 where the object file will reside if/when it is created.
140 %************************************************************************
142 \subsection{Symbol tables and Module details}
144 %************************************************************************
146 A @ModIface@ plus a @ModDetails@ summarises everything we know
147 about a compiled module. The @ModIface@ is the stuff *before* linking,
148 and can be written out to an interface file. (The @ModDetails@ is after
149 linking; it is the "linked" form of the mi_decls field.)
151 When we *read* an interface file, we also construct a @ModIface@ from it,
152 except that the mi_decls part is empty; when reading we consolidate
153 the declarations into a single indexed map in the @PersistentRenamerState@.
158 mi_module :: !Module,
159 mi_package :: !PackageName, -- Which package the module comes from
160 mi_version :: !VersionInfo, -- Module version number
162 mi_orphan :: WhetherHasOrphans, -- Whether this module has orphans
163 -- NOT STRICT! we fill this field with _|_ sometimes
165 mi_boot :: !IsBootInterface, -- read from an hi-boot file?
167 mi_usages :: ![ImportVersion Name],
168 -- Usages; kept sorted so that it's easy to decide
169 -- whether to write a new iface file (changing usages
170 -- doesn't affect the version of this module)
172 mi_exports :: ![(ModuleName,Avails)],
173 -- What it exports Kept sorted by (mod,occ), to make
174 -- version comparisons easier
176 mi_globals :: !(Maybe GlobalRdrEnv),
177 -- Its top level environment or Nothing if we read this
178 -- interface from a file.
180 mi_fixities :: !(NameEnv Fixity), -- Fixities
181 mi_deprecs :: !Deprecations, -- Deprecations
183 mi_decls :: IfaceDecls -- The RnDecls form of ModDetails
184 -- NOT STRICT! we fill this field with _|_ sometimes
187 data IfaceDecls = IfaceDecls { dcl_tycl :: [RenamedTyClDecl], -- Sorted
188 dcl_rules :: [RenamedRuleDecl], -- Sorted
189 dcl_insts :: [RenamedInstDecl] } -- Unsorted
191 mkIfaceDecls :: [RenamedTyClDecl] -> [RenamedRuleDecl] -> [RenamedInstDecl] -> IfaceDecls
192 mkIfaceDecls tycls rules insts
193 = IfaceDecls { dcl_tycl = sortLt lt_tycl tycls,
194 dcl_rules = sortLt lt_rule rules,
197 d1 `lt_tycl` d2 = tyClDeclName d1 < tyClDeclName d2
198 r1 `lt_rule` r2 = ifaceRuleDeclName r1 < ifaceRuleDeclName r2
201 -- typechecker should only look at this, not ModIface
202 -- Should be able to construct ModDetails from mi_decls in ModIface
205 -- The next three fields are created by the typechecker
206 md_types :: !TypeEnv,
207 md_insts :: ![DFunId], -- Dfun-ids for the instances in this module
208 md_rules :: ![IdCoreRule], -- Domain may include Ids from other modules
209 md_binds :: ![CoreBind]
212 -- The ModDetails takes on several slightly different forms:
214 -- After typecheck + desugar
215 -- md_types Contains TyCons, Classes, and implicit Ids
216 -- md_insts All instances from this module (incl derived ones)
217 -- md_rules All rules from this module
218 -- md_binds Desugared bindings
220 -- After simplification
221 -- md_types Same as after typecheck
223 -- md_rules Orphan rules only (local ones now attached to binds)
224 -- md_binds With rules attached
227 -- md_types Now contains Ids as well, replete with final IdInfo
228 -- The Ids are only the ones that are visible from
229 -- importing modules. Without -O that means only
230 -- exported Ids, but with -O importing modules may
231 -- see ids mentioned in unfoldings of exported Ids
233 -- md_insts Same DFunIds as before, but with final IdInfo,
234 -- and the unique might have changed; remember that
235 -- CoreTidy links up the uniques of old and new versions
237 -- md_rules All rules for exported things, substituted with final Ids
241 -- Passed back to compilation manager
242 -- Just as after CoreTidy, but with md_binds nuked
247 emptyModIface :: Module -> ModIface
249 = ModIface { mi_module = mod,
250 mi_package = preludePackage, -- XXX fully bogus
251 mi_version = initialVersionInfo,
256 mi_fixities = emptyNameEnv,
257 mi_globals = Nothing,
258 mi_deprecs = NoDeprecs,
259 mi_decls = panic "emptyModIface: decls"
263 Symbol tables map modules to ModDetails:
266 type SymbolTable = ModuleEnv ModDetails
267 type IfaceTable = ModuleEnv ModIface
269 type HomeIfaceTable = IfaceTable
270 type PackageIfaceTable = IfaceTable
272 type HomeSymbolTable = SymbolTable -- Domain = modules in the home package
274 emptySymbolTable :: SymbolTable
275 emptySymbolTable = emptyModuleEnv
277 emptyIfaceTable :: IfaceTable
278 emptyIfaceTable = emptyModuleEnv
281 Simple lookups in the symbol table.
284 lookupIface :: HomeIfaceTable -> PackageIfaceTable -> Name -> Maybe ModIface
285 -- We often have two IfaceTables, and want to do a lookup
286 lookupIface hit pit name
287 = lookupModuleEnv hit mod `seqMaybe` lookupModuleEnv pit mod
289 mod = nameModule name
291 lookupIfaceByModName :: HomeIfaceTable -> PackageIfaceTable -> ModuleName -> Maybe ModIface
292 -- We often have two IfaceTables, and want to do a lookup
293 lookupIfaceByModName hit pit mod
294 = lookupModuleEnvByName hit mod `seqMaybe` lookupModuleEnvByName pit mod
298 %************************************************************************
300 \subsection{The interactive context}
302 %************************************************************************
305 data InteractiveContext
306 = InteractiveContext {
307 ic_toplev_scope :: [Module], -- Include the "top-level" scope of
310 ic_exports :: [Module], -- Include just the exports of these
313 ic_rn_gbl_env :: GlobalRdrEnv, -- The cached GlobalRdrEnv, built from
314 -- ic_toplev_scope and ic_exports
316 ic_print_unqual :: PrintUnqualified,
317 -- cached PrintUnqualified, as above
319 ic_rn_local_env :: LocalRdrEnv, -- Lexical context for variables bound
320 -- during interaction
322 ic_type_env :: TypeEnv -- Ditto for types
327 %************************************************************************
329 \subsection{Type environment stuff}
331 %************************************************************************
334 data TyThing = AnId Id
338 isTyClThing :: TyThing -> Bool
339 isTyClThing (ATyCon _) = True
340 isTyClThing (AClass _) = True
341 isTyClThing (AnId _) = False
343 instance NamedThing TyThing where
344 getName (AnId id) = getName id
345 getName (ATyCon tc) = getName tc
346 getName (AClass cl) = getName cl
348 instance Outputable TyThing where
349 ppr (AnId id) = ptext SLIT("AnId") <+> ppr id
350 ppr (ATyCon tc) = ptext SLIT("ATyCon") <+> ppr tc
351 ppr (AClass cl) = ptext SLIT("AClass") <+> ppr cl
354 typeEnvElts :: TypeEnv -> [TyThing]
355 typeEnvClasses :: TypeEnv -> [Class]
356 typeEnvTyCons :: TypeEnv -> [TyCon]
357 typeEnvIds :: TypeEnv -> [Id]
359 typeEnvElts env = nameEnvElts env
360 typeEnvClasses env = [cl | AClass cl <- typeEnvElts env]
361 typeEnvTyCons env = [tc | ATyCon tc <- typeEnvElts env]
362 typeEnvIds env = [id | AnId id <- typeEnvElts env]
364 implicitTyThingIds :: [TyThing] -> [Id]
365 -- Add the implicit data cons and selectors etc
366 implicitTyThingIds things
367 = concat (map go things)
370 go (AClass cl) = classSelIds cl
371 go (ATyCon tc) = tyConGenIds tc ++
373 [ n | dc <- tyConDataConsIfAvailable tc,
374 n <- implicitConIds tc dc]
375 -- Synonyms return empty list of constructors and selectors
377 implicitConIds tc dc -- Newtypes have a constructor wrapper,
379 | isNewTyCon tc = [dataConWrapId dc]
380 | otherwise = [dataConId dc, dataConWrapId dc]
385 type TypeEnv = NameEnv TyThing
387 emptyTypeEnv = emptyNameEnv
389 mkTypeEnv :: [TyThing] -> TypeEnv
390 mkTypeEnv things = extendTypeEnvList emptyTypeEnv things
392 extendTypeEnvList :: TypeEnv -> [TyThing] -> TypeEnv
393 extendTypeEnvList env things
394 = extendNameEnvList env [(getName thing, thing) | thing <- things]
396 extendTypeEnvWithIds :: TypeEnv -> [Id] -> TypeEnv
397 extendTypeEnvWithIds env ids
398 = extendNameEnvList env [(getName id, AnId id) | id <- ids]
402 lookupType :: HomeSymbolTable -> PackageTypeEnv -> Name -> Maybe TyThing
403 lookupType hst pte name
404 = case lookupModuleEnv hst (nameModule name) of
405 Just details -> lookupNameEnv (md_types details) name
406 Nothing -> lookupNameEnv pte name
409 %************************************************************************
411 \subsection{Auxiliary types}
413 %************************************************************************
415 These types are defined here because they are mentioned in ModDetails,
416 but they are mostly elaborated elsewhere
421 vers_module :: Version, -- Changes when anything changes
422 vers_exports :: Version, -- Changes when export list changes
423 vers_rules :: Version, -- Changes when any rule changes
424 vers_decls :: NameEnv Version
425 -- Versions for "big" names only (not data constructors, class ops)
426 -- The version of an Id changes if its fixity changes
427 -- Ditto data constructors, class operations, except that the version of
428 -- the parent class/tycon changes
430 -- If a name isn't in the map, it means 'initialVersion'
433 initialVersionInfo :: VersionInfo
434 initialVersionInfo = VersionInfo { vers_module = initialVersion,
435 vers_exports = initialVersion,
436 vers_rules = initialVersion,
437 vers_decls = emptyNameEnv
440 lookupVersion :: NameEnv Version -> Name -> Version
441 lookupVersion env name = lookupNameEnv env name `orElse` initialVersion
443 data Deprecations = NoDeprecs
444 | DeprecAll DeprecTxt -- Whole module deprecated
445 | DeprecSome (NameEnv (Name,DeprecTxt)) -- Some things deprecated
447 -- We keep the Name in the range, so we can print them out
449 lookupDeprec :: Deprecations -> Name -> Maybe DeprecTxt
450 lookupDeprec NoDeprecs name = Nothing
451 lookupDeprec (DeprecAll txt) name = Just txt
452 lookupDeprec (DeprecSome env) name = case lookupNameEnv env name of
453 Just (_, txt) -> Just txt
456 instance Eq Deprecations where
457 -- Used when checking whether we need write a new interface
458 NoDeprecs == NoDeprecs = True
459 (DeprecAll t1) == (DeprecAll t2) = t1 == t2
460 (DeprecSome e1) == (DeprecSome e2) = nameEnvElts e1 == nameEnvElts e2
466 type Avails = [AvailInfo]
467 type AvailInfo = GenAvailInfo Name
468 type RdrAvailInfo = GenAvailInfo OccName
470 data GenAvailInfo name = Avail name -- An ordinary identifier
471 | AvailTC name -- The name of the type or class
472 [name] -- The available pieces of type/class.
473 -- NB: If the type or class is itself
474 -- to be in scope, it must be in this list.
475 -- Thus, typically: AvailTC Eq [Eq, ==, /=]
477 -- Equality used when deciding if the interface has changed
479 type AvailEnv = NameEnv AvailInfo -- Maps a Name to the AvailInfo that contains it
481 emptyAvailEnv :: AvailEnv
482 emptyAvailEnv = emptyNameEnv
484 instance Outputable n => Outputable (GenAvailInfo n) where
487 pprAvail :: Outputable n => GenAvailInfo n -> SDoc
488 pprAvail (AvailTC n ns) = ppr n <> case {- filter (/= n) -} ns of
490 ns' -> braces (hsep (punctuate comma (map ppr ns')))
492 pprAvail (Avail n) = ppr n
496 %************************************************************************
498 \subsection{ModIface}
500 %************************************************************************
503 type WhetherHasOrphans = Bool
505 -- * an instance decl in a module other than the defn module for
506 -- one of the tycons or classes in the instance head
507 -- * a transformation rule in a module other than the one defining
508 -- the function in the head of the rule.
510 type IsBootInterface = Bool
512 type ImportVersion name = (ModuleName, WhetherHasOrphans, IsBootInterface, WhatsImported name)
514 data WhatsImported name = NothingAtAll -- The module is below us in the
515 -- hierarchy, but we import nothing
517 | Everything Version -- Used for modules from other packages;
518 -- we record only the module's version number
521 Version -- Module version
522 (Maybe Version) -- Export-list version, if we depend on it
523 [(name,Version)] -- List guaranteed non-empty
524 Version -- Rules version
527 -- 'Specifically' doesn't let you say "I imported f but none of the rules in
528 -- the module". If you use anything in the module you get its rule version
529 -- So if the rules change, you'll recompile, even if you don't use them.
530 -- This is easy to implement, and it's safer: you might not have used the rules last
531 -- time round, but if someone has added a new rule you might need it this time
533 -- The export list field is (Just v) if we depend on the export list:
534 -- we imported the module without saying exactly what we imported
535 -- We need to recompile if the module exports changes, because we might
536 -- now have a name clash in the importing module.
538 type IsExported = Name -> Bool -- True for names that are exported from this module
542 %************************************************************************
544 \subsection{The persistent compiler state}
546 %************************************************************************
548 The @PersistentCompilerState@ persists across successive calls to the
551 * A ModIface for each non-home-package module
553 * An accumulated TypeEnv from all the modules in imported packages
555 * An accumulated InstEnv from all the modules in imported packages
556 The point is that we don't want to keep recreating it whenever
557 we compile a new module. The InstEnv component of pcPST is empty.
558 (This means we might "see" instances that we shouldn't "really" see;
559 but the Haskell Report is vague on what is meant to be visible,
560 so we just take the easy road here.)
564 * The persistent renamer state
567 data PersistentCompilerState
569 pcs_PIT :: !PackageIfaceTable, -- Domain = non-home-package modules
570 -- the mi_decls component is empty
572 pcs_PTE :: !PackageTypeEnv, -- Domain = non-home-package modules
573 -- except that the InstEnv components is empty
575 pcs_insts :: !PackageInstEnv, -- The total InstEnv accumulated from all
576 -- the non-home-package modules
578 pcs_rules :: !PackageRuleBase, -- Ditto RuleEnv
580 pcs_PRS :: !PersistentRenamerState
585 The persistent renamer state contains:
587 * A name supply, which deals with allocating unique names to
588 (Module,OccName) original names,
590 * A "holding pen" for declarations that have been read out of
591 interface files but not yet sucked in, renamed, and typechecked
594 type PackageTypeEnv = TypeEnv
595 type PackageRuleBase = RuleBase
596 type PackageInstEnv = InstEnv
598 data PersistentRenamerState
599 = PRS { prsOrig :: !NameSupply,
600 prsImpMods :: !ImportedModuleInfo,
602 -- Holding pens for stuff that has been read in
603 -- but not yet slurped into the renamer
604 prsDecls :: !DeclsMap,
605 prsInsts :: !IfaceInsts,
606 prsRules :: !IfaceRules
610 The NameSupply makes sure that there is just one Unique assigned for
611 each original name; i.e. (module-name, occ-name) pair. The Name is
612 always stored as a Global, and has the SrcLoc of its binding location.
613 Actually that's not quite right. When we first encounter the original
614 name, we might not be at its binding site (e.g. we are reading an
615 interface file); so we give it 'noSrcLoc' then. Later, when we find
616 its binding site, we fix it up.
618 Exactly the same is true of the Module stored in the Name. When we first
619 encounter the occurrence, we may not know the details of the module, so
620 we just store junk. Then when we find the binding site, we fix it up.
624 = NameSupply { nsUniqs :: UniqSupply,
626 nsNames :: OrigNameCache,
627 -- Ensures that one original name gets one unique
628 nsIPs :: OrigIParamCache
629 -- Ensures that one implicit parameter name gets one unique
632 type OrigNameCache = FiniteMap (ModuleName,OccName) Name
633 type OrigIParamCache = FiniteMap (IPName RdrName) (IPName Name)
636 @ImportedModuleInfo@ contains info ONLY about modules that have not yet
637 been loaded into the iPIT. These modules are mentioned in interfaces we've
638 already read, so we know a tiny bit about them, but we havn't yet looked
639 at the interface file for the module itself. It needs to persist across
640 invocations of the renamer, at least from Rename.checkOldIface to Rename.renameSource.
641 And there's no harm in it persisting across multiple compilations.
644 type ImportedModuleInfo = FiniteMap ModuleName (WhetherHasOrphans, IsBootInterface)
647 A DeclsMap contains a binding for each Name in the declaration
648 including the constructors of a type decl etc. The Bool is True just
652 type DeclsMap = (NameEnv (AvailInfo, Bool, (Module, RdrNameTyClDecl)), Int)
653 -- The Int says how many have been sucked in
655 type IfaceInsts = GatedDecls RdrNameInstDecl
656 type IfaceRules = GatedDecls RdrNameRuleDecl
658 type GatedDecls d = (Bag (GatedDecl d), Int) -- The Int says how many have been sucked in
659 type GatedDecl d = (GateFn, (Module, d))
660 type GateFn = (Name -> Bool) -> Bool -- Returns True <=> gate is open
661 -- The (Name -> Bool) fn returns True for visible Names
662 -- For example, suppose this is in an interface file
663 -- instance C T where ...
664 -- We want to slurp this decl if both C and T are "visible" in
665 -- the importing module. See "The gating story" in RnIfaces for details.
669 %************************************************************************
671 \subsection{Provenance and export info}
673 %************************************************************************
675 A LocalRdrEnv is used for local bindings (let, where, lambda, case)
678 type LocalRdrEnv = RdrNameEnv Name
680 extendLocalRdrEnv :: LocalRdrEnv -> [Name] -> LocalRdrEnv
681 extendLocalRdrEnv env names
682 = addListToRdrEnv env [(mkRdrUnqual (nameOccName n), n) | n <- names]
685 The GlobalRdrEnv gives maps RdrNames to Names. There is a separate
686 one for each module, corresponding to that module's top-level scope.
689 type GlobalRdrEnv = RdrNameEnv [GlobalRdrElt]
690 -- The list is because there may be name clashes
691 -- These only get reported on lookup, not on construction
693 data GlobalRdrElt = GRE Name Provenance (Maybe DeprecTxt)
694 -- The Maybe DeprecTxt tells whether this name is deprecated
697 = vcat (map pp (rdrEnvToList env))
699 pp (rn, nps) = ppr rn <> colon <+>
700 vcat [ppr n <+> pprNameProvenance n p | (GRE n p _) <- nps]
703 The "provenance" of something says how it came to be in scope.
707 = LocalDef -- Defined locally
709 | NonLocalDef -- Defined non-locally
712 -- Just used for grouping error messages (in RnEnv.warnUnusedBinds)
713 instance Eq Provenance where
714 p1 == p2 = case p1 `compare` p2 of EQ -> True; _ -> False
716 instance Eq ImportReason where
717 p1 == p2 = case p1 `compare` p2 of EQ -> True; _ -> False
719 instance Ord Provenance where
720 compare LocalDef LocalDef = EQ
721 compare LocalDef (NonLocalDef _) = LT
722 compare (NonLocalDef _) LocalDef = GT
724 compare (NonLocalDef reason1) (NonLocalDef reason2)
725 = compare reason1 reason2
727 instance Ord ImportReason where
728 compare ImplicitImport ImplicitImport = EQ
729 compare ImplicitImport (UserImport _ _ _) = LT
730 compare (UserImport _ _ _) ImplicitImport = GT
731 compare (UserImport m1 loc1 _) (UserImport m2 loc2 _)
732 = (m1 `compare` m2) `thenCmp` (loc1 `compare` loc2)
736 = UserImport Module SrcLoc Bool -- Imported from module M on line L
737 -- Note the M may well not be the defining module
739 -- The Bool is true iff the thing was named *explicitly* in the import spec,
740 -- rather than being imported as part of a group; e.g.
743 -- Here, everything imported by B, and the constructors of T
744 -- are not named explicitly; only T is named explicitly.
745 -- This info is used when warning of unused names.
747 | ImplicitImport -- Imported implicitly for some other reason
751 hasBetterProv :: Provenance -> Provenance -> Bool
753 -- a local thing over an imported thing
754 -- a user-imported thing over a non-user-imported thing
755 -- an explicitly-imported thing over an implicitly imported thing
756 hasBetterProv LocalDef _ = True
757 hasBetterProv (NonLocalDef (UserImport _ _ _ )) (NonLocalDef ImplicitImport) = True
758 hasBetterProv _ _ = False
760 pprNameProvenance :: Name -> Provenance -> SDoc
761 pprNameProvenance name LocalDef = ptext SLIT("defined at") <+> ppr (nameSrcLoc name)
762 pprNameProvenance name (NonLocalDef why) = sep [ppr_reason why,
763 nest 2 (ppr_defn (nameSrcLoc name))]
765 ppr_reason ImplicitImport = ptext SLIT("implicitly imported")
766 ppr_reason (UserImport mod loc _) = ptext SLIT("imported from") <+> ppr mod <+> ptext SLIT("at") <+> ppr loc
768 ppr_defn loc | isGoodSrcLoc loc = parens (ptext SLIT("at") <+> ppr loc)