2 % (c) The University of Glasgow 2006
3 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
10 -- GHC uses several kinds of name internally:
12 -- * 'OccName.OccName': see "OccName#name_types"
14 -- * 'RdrName.RdrName' is the type of names that come directly from the parser. They
15 -- have not yet had their scoping and binding resolved by the renamer and can be
16 -- thought of to a first approximation as an 'OccName.OccName' with an optional module
19 -- * 'Name.Name': see "Name#name_types"
21 -- * 'Id.Id': see "Id#name_types"
23 -- * 'Var.Var': see "Var#name_types"
26 RdrName(..), -- Constructors exported only to BinIface
29 mkRdrUnqual, mkRdrQual,
30 mkUnqual, mkVarUnqual, mkQual, mkOrig,
31 nameRdrName, getRdrName,
35 rdrNameOcc, rdrNameSpace, setRdrNameSpace,
36 isRdrDataCon, isRdrTyVar, isRdrTc, isQual, isQual_maybe, isUnqual,
37 isOrig, isOrig_maybe, isExact, isExact_maybe, isSrcRdrName,
42 -- * Local mapping of 'RdrName' to 'Name.Name'
43 LocalRdrEnv, emptyLocalRdrEnv, extendLocalRdrEnv,
44 lookupLocalRdrEnv, lookupLocalRdrOcc, elemLocalRdrEnv,
46 -- * Global mapping of 'RdrName' to 'GlobalRdrElt's
47 GlobalRdrEnv, emptyGlobalRdrEnv, mkGlobalRdrEnv, plusGlobalRdrEnv,
48 lookupGlobalRdrEnv, extendGlobalRdrEnv,
49 pprGlobalRdrEnv, globalRdrEnvElts,
50 lookupGRE_RdrName, lookupGRE_Name, getGRE_NameQualifier_maybes,
51 hideSomeUnquals, findLocalDupsRdrEnv,
53 -- ** Global 'RdrName' mapping elements: 'GlobalRdrElt', 'Provenance', 'ImportSpec'
54 GlobalRdrElt(..), isLocalGRE, unQualOK, qualSpecOK, unQualSpecOK,
55 Provenance(..), pprNameProvenance,
57 ImportSpec(..), ImpDeclSpec(..), ImpItemSpec(..),
58 importSpecLoc, importSpecModule, isExplicitItem
61 #include "HsVersions.h"
72 %************************************************************************
74 \subsection{The main data type}
76 %************************************************************************
79 -- | Do not use the data constructors of RdrName directly: prefer the family
80 -- of functions that creates them, such as 'mkRdrUnqual'
83 -- ^ Used for ordinary, unqualified occurrences, e.g. @x@, @y@ or @Foo@.
84 -- Create such a 'RdrName' with 'mkRdrUnqual'
86 | Qual ModuleName OccName
87 -- ^ A qualified name written by the user in
88 -- /source/ code. The module isn't necessarily
89 -- the module where the thing is defined;
90 -- just the one from which it is imported.
91 -- Examples are @Bar.x@, @Bar.y@ or @Bar.Foo@.
92 -- Create such a 'RdrName' with 'mkRdrQual'
95 -- ^ An original name; the module is the /defining/ module.
96 -- This is used when GHC generates code that will be fed
97 -- into the renamer (e.g. from deriving clauses), but where
98 -- we want to say \"Use Prelude.map dammit\". One of these
99 -- can be created with 'mkOrig'
102 -- ^ We know exactly the 'Name'. This is used:
104 -- (1) When the parser parses built-in syntax like @[]@
105 -- and @(,)@, but wants a 'RdrName' from it
107 -- (2) By Template Haskell, when TH has generated a unique name
109 -- Such a 'RdrName' can be created by using 'getRdrName' on a 'Name'
113 %************************************************************************
115 \subsection{Simple functions}
117 %************************************************************************
120 rdrNameOcc :: RdrName -> OccName
121 rdrNameOcc (Qual _ occ) = occ
122 rdrNameOcc (Unqual occ) = occ
123 rdrNameOcc (Orig _ occ) = occ
124 rdrNameOcc (Exact name) = nameOccName name
126 rdrNameSpace :: RdrName -> NameSpace
127 rdrNameSpace = occNameSpace . rdrNameOcc
129 setRdrNameSpace :: RdrName -> NameSpace -> RdrName
130 -- ^ This rather gruesome function is used mainly by the parser.
133 -- > data T a = T | T1 Int
135 -- we parse the data constructors as /types/ because of parser ambiguities,
136 -- so then we need to change the /type constr/ to a /data constr/
138 -- The exact-name case /can/ occur when parsing:
140 -- > data [] a = [] | a : [a]
142 -- For the exact-name case we return an original name.
143 setRdrNameSpace (Unqual occ) ns = Unqual (setOccNameSpace ns occ)
144 setRdrNameSpace (Qual m occ) ns = Qual m (setOccNameSpace ns occ)
145 setRdrNameSpace (Orig m occ) ns = Orig m (setOccNameSpace ns occ)
146 setRdrNameSpace (Exact n) ns = Orig (nameModule n)
147 (setOccNameSpace ns (nameOccName n))
151 -- These two are the basic constructors
152 mkRdrUnqual :: OccName -> RdrName
153 mkRdrUnqual occ = Unqual occ
155 mkRdrQual :: ModuleName -> OccName -> RdrName
156 mkRdrQual mod occ = Qual mod occ
158 mkOrig :: Module -> OccName -> RdrName
159 mkOrig mod occ = Orig mod occ
162 -- | Produce an original 'RdrName' whose module that of a parent 'Name' but its 'OccName'
163 -- is derived from that of it's parent using the supplied function
164 mkDerivedRdrName :: Name -> (OccName -> OccName) -> RdrName
165 mkDerivedRdrName parent mk_occ
166 = mkOrig (nameModule parent) (mk_occ (nameOccName parent))
169 -- These two are used when parsing source files
170 -- They do encode the module and occurrence names
171 mkUnqual :: NameSpace -> FastString -> RdrName
172 mkUnqual sp n = Unqual (mkOccNameFS sp n)
174 mkVarUnqual :: FastString -> RdrName
175 mkVarUnqual n = Unqual (mkVarOccFS n)
177 -- | Make a qualified 'RdrName' in the given namespace and where the 'ModuleName' and
178 -- the 'OccName' are taken from the first and second elements of the tuple respectively
179 mkQual :: NameSpace -> (FastString, FastString) -> RdrName
180 mkQual sp (m, n) = Qual (mkModuleNameFS m) (mkOccNameFS sp n)
182 getRdrName :: NamedThing thing => thing -> RdrName
183 getRdrName name = nameRdrName (getName name)
185 nameRdrName :: Name -> RdrName
186 nameRdrName name = Exact name
187 -- Keep the Name even for Internal names, so that the
188 -- unique is still there for debug printing, particularly
189 -- of Types (which are converted to IfaceTypes before printing)
191 nukeExact :: Name -> RdrName
193 | isExternalName n = Orig (nameModule n) (nameOccName n)
194 | otherwise = Unqual (nameOccName n)
198 isRdrDataCon :: RdrName -> Bool
199 isRdrTyVar :: RdrName -> Bool
200 isRdrTc :: RdrName -> Bool
202 isRdrDataCon rn = isDataOcc (rdrNameOcc rn)
203 isRdrTyVar rn = isTvOcc (rdrNameOcc rn)
204 isRdrTc rn = isTcOcc (rdrNameOcc rn)
206 isSrcRdrName :: RdrName -> Bool
207 isSrcRdrName (Unqual _) = True
208 isSrcRdrName (Qual _ _) = True
209 isSrcRdrName _ = False
211 isUnqual :: RdrName -> Bool
212 isUnqual (Unqual _) = True
215 isQual :: RdrName -> Bool
216 isQual (Qual _ _) = True
219 isQual_maybe :: RdrName -> Maybe (ModuleName, OccName)
220 isQual_maybe (Qual m n) = Just (m,n)
221 isQual_maybe _ = Nothing
223 isOrig :: RdrName -> Bool
224 isOrig (Orig _ _) = True
227 isOrig_maybe :: RdrName -> Maybe (Module, OccName)
228 isOrig_maybe (Orig m n) = Just (m,n)
229 isOrig_maybe _ = Nothing
231 isExact :: RdrName -> Bool
232 isExact (Exact _) = True
235 isExact_maybe :: RdrName -> Maybe Name
236 isExact_maybe (Exact n) = Just n
237 isExact_maybe _ = Nothing
241 %************************************************************************
243 \subsection{Instances}
245 %************************************************************************
248 instance Outputable RdrName where
249 ppr (Exact name) = ppr name
250 ppr (Unqual occ) = ppr occ
251 ppr (Qual mod occ) = ppr mod <> dot <> ppr occ
252 ppr (Orig mod occ) = ppr mod <> dot <> ppr occ
254 instance OutputableBndr RdrName where
256 | isTvOcc (rdrNameOcc n) = char '@' <+> ppr n
259 showRdrName :: RdrName -> String
260 showRdrName r = showSDoc (ppr r)
262 instance Eq RdrName where
263 (Exact n1) == (Exact n2) = n1==n2
264 -- Convert exact to orig
265 (Exact n1) == r2@(Orig _ _) = nukeExact n1 == r2
266 r1@(Orig _ _) == (Exact n2) = r1 == nukeExact n2
268 (Orig m1 o1) == (Orig m2 o2) = m1==m2 && o1==o2
269 (Qual m1 o1) == (Qual m2 o2) = m1==m2 && o1==o2
270 (Unqual o1) == (Unqual o2) = o1==o2
273 instance Ord RdrName where
274 a <= b = case (a `compare` b) of { LT -> True; EQ -> True; GT -> False }
275 a < b = case (a `compare` b) of { LT -> True; EQ -> False; GT -> False }
276 a >= b = case (a `compare` b) of { LT -> False; EQ -> True; GT -> True }
277 a > b = case (a `compare` b) of { LT -> False; EQ -> False; GT -> True }
279 -- Exact < Unqual < Qual < Orig
280 -- [Note: Apr 2004] We used to use nukeExact to convert Exact to Orig
281 -- before comparing so that Prelude.map == the exact Prelude.map, but
282 -- that meant that we reported duplicates when renaming bindings
283 -- generated by Template Haskell; e.g
284 -- do { n1 <- newName "foo"; n2 <- newName "foo";
285 -- <decl involving n1,n2> }
286 -- I think we can do without this conversion
287 compare (Exact n1) (Exact n2) = n1 `compare` n2
288 compare (Exact _) _ = LT
290 compare (Unqual _) (Exact _) = GT
291 compare (Unqual o1) (Unqual o2) = o1 `compare` o2
292 compare (Unqual _) _ = LT
294 compare (Qual _ _) (Exact _) = GT
295 compare (Qual _ _) (Unqual _) = GT
296 compare (Qual m1 o1) (Qual m2 o2) = (o1 `compare` o2) `thenCmp` (m1 `compare` m2)
297 compare (Qual _ _) (Orig _ _) = LT
299 compare (Orig m1 o1) (Orig m2 o2) = (o1 `compare` o2) `thenCmp` (m1 `compare` m2)
300 compare (Orig _ _) _ = GT
303 %************************************************************************
307 %************************************************************************
310 -- | This environment is used to store local bindings (@let@, @where@, lambda, @case@).
311 -- It is keyed by OccName, because we never use it for qualified names
312 type LocalRdrEnv = OccEnv Name
314 emptyLocalRdrEnv :: LocalRdrEnv
315 emptyLocalRdrEnv = emptyOccEnv
317 extendLocalRdrEnv :: LocalRdrEnv -> [Name] -> LocalRdrEnv
318 extendLocalRdrEnv env names
319 = extendOccEnvList env [(nameOccName n, n) | n <- names]
321 lookupLocalRdrEnv :: LocalRdrEnv -> RdrName -> Maybe Name
322 lookupLocalRdrEnv _ (Exact name) = Just name
323 lookupLocalRdrEnv env (Unqual occ) = lookupOccEnv env occ
324 lookupLocalRdrEnv _ _ = Nothing
326 lookupLocalRdrOcc :: LocalRdrEnv -> OccName -> Maybe Name
327 lookupLocalRdrOcc env occ = lookupOccEnv env occ
329 elemLocalRdrEnv :: RdrName -> LocalRdrEnv -> Bool
330 elemLocalRdrEnv rdr_name env
331 | isUnqual rdr_name = rdrNameOcc rdr_name `elemOccEnv` env
335 %************************************************************************
339 %************************************************************************
342 type GlobalRdrEnv = OccEnv [GlobalRdrElt]
343 -- ^ Keyed by 'OccName'; when looking up a qualified name
344 -- we look up the 'OccName' part, and then check the 'Provenance'
345 -- to see if the appropriate qualification is valid. This
346 -- saves routinely doubling the size of the env by adding both
347 -- qualified and unqualified names to the domain.
349 -- The list in the codomain is required because there may be name clashes
350 -- These only get reported on lookup, not on construction
352 -- INVARIANT: All the members of the list have distinct
353 -- 'gre_name' fields; that is, no duplicate Names
355 -- | An element of the 'GlobalRdrEnv'
357 = GRE { gre_name :: Name,
359 gre_prov :: Provenance -- ^ Why it's in scope
362 data Parent = NoParent | ParentIs Name
365 instance Outputable Parent where
367 ppr (ParentIs n) = ptext (sLit "parent:") <> ppr n
370 plusParent :: Parent -> Parent -> Parent
371 plusParent p1 p2 = ASSERT2( p1 == p2, parens (ppr p1) <+> parens (ppr p2) )
374 {- Why so complicated? -=chak
375 plusParent :: Parent -> Parent -> Parent
376 plusParent NoParent rel =
377 ASSERT2( case rel of { NoParent -> True; other -> False },
378 ptext (sLit "plusParent[NoParent]: ") <+> ppr rel )
380 plusParent (ParentIs n) rel =
381 ASSERT2( case rel of { ParentIs m -> n==m; other -> False },
382 ptext (sLit "plusParent[ParentIs]:") <+> ppr n <> comma <+> ppr rel )
386 emptyGlobalRdrEnv :: GlobalRdrEnv
387 emptyGlobalRdrEnv = emptyOccEnv
389 globalRdrEnvElts :: GlobalRdrEnv -> [GlobalRdrElt]
390 globalRdrEnvElts env = foldOccEnv (++) [] env
392 instance Outputable GlobalRdrElt where
393 ppr gre = ppr name <+> parens (ppr (gre_par gre) <+> pprNameProvenance gre)
397 pprGlobalRdrEnv :: GlobalRdrEnv -> SDoc
399 = vcat (map pp (occEnvElts env))
401 pp gres = ppr (nameOccName (gre_name (head gres))) <> colon <+>
402 vcat [ ppr (gre_name gre) <+> pprNameProvenance gre
407 lookupGlobalRdrEnv :: GlobalRdrEnv -> OccName -> [GlobalRdrElt]
408 lookupGlobalRdrEnv env occ_name = case lookupOccEnv env occ_name of
412 extendGlobalRdrEnv :: GlobalRdrEnv -> GlobalRdrElt -> GlobalRdrEnv
413 extendGlobalRdrEnv env gre = extendOccEnv_C add env occ [gre]
415 occ = nameOccName (gre_name gre)
416 add gres _ = gre:gres
418 lookupGRE_RdrName :: RdrName -> GlobalRdrEnv -> [GlobalRdrElt]
419 lookupGRE_RdrName rdr_name env
420 = case lookupOccEnv env (rdrNameOcc rdr_name) of
422 Just gres -> pickGREs rdr_name gres
424 lookupGRE_Name :: GlobalRdrEnv -> Name -> [GlobalRdrElt]
425 lookupGRE_Name env name
426 = [ gre | gre <- lookupGlobalRdrEnv env (nameOccName name),
427 gre_name gre == name ]
429 getGRE_NameQualifier_maybes :: GlobalRdrEnv -> Name -> [Maybe [ModuleName]]
430 getGRE_NameQualifier_maybes env
431 = map qualifier_maybe . map gre_prov . lookupGRE_Name env
432 where qualifier_maybe LocalDef = Nothing
433 qualifier_maybe (Imported iss) = Just $ map (is_as . is_decl) iss
435 pickGREs :: RdrName -> [GlobalRdrElt] -> [GlobalRdrElt]
436 -- ^ Take a list of GREs which have the right OccName
437 -- Pick those GREs that are suitable for this RdrName
438 -- And for those, keep only only the Provenances that are suitable
443 -- module A ( f ) where
444 -- import qualified Foo( f )
449 -- Let's suppose that @Foo.f@ and @Baz.f@ are the same entity really.
450 -- The export of @f@ is ambiguous because it's in scope from the local def
451 -- and the import. The lookup of @Unqual f@ should return a GRE for
452 -- the locally-defined @f@, and a GRE for the imported @f@, with a /single/
453 -- provenance, namely the one for @Baz(f)@.
454 pickGREs rdr_name gres
455 = mapCatMaybes pick gres
457 rdr_is_unqual = isUnqual rdr_name
458 rdr_is_qual = isQual_maybe rdr_name
460 pick :: GlobalRdrElt -> Maybe GlobalRdrElt
461 pick gre@(GRE {gre_prov = LocalDef, gre_name = n}) -- Local def
462 | rdr_is_unqual = Just gre
463 | Just (mod,_) <- rdr_is_qual,
464 mod == moduleName (nameModule n) = Just gre
465 | otherwise = Nothing
466 pick gre@(GRE {gre_prov = Imported [is]}) -- Single import (efficiency)
468 not (is_qual (is_decl is)) = Just gre
469 | Just (mod,_) <- rdr_is_qual,
470 mod == is_as (is_decl is) = Just gre
471 | otherwise = Nothing
472 pick gre@(GRE {gre_prov = Imported is}) -- Multiple import
473 | null filtered_is = Nothing
474 | otherwise = Just (gre {gre_prov = Imported filtered_is})
476 filtered_is | rdr_is_unqual
477 = filter (not . is_qual . is_decl) is
478 | Just (mod,_) <- rdr_is_qual
479 = filter ((== mod) . is_as . is_decl) is
483 isLocalGRE :: GlobalRdrElt -> Bool
484 isLocalGRE (GRE {gre_prov = LocalDef}) = True
487 unQualOK :: GlobalRdrElt -> Bool
488 -- ^ Test if an unqualifed version of this thing would be in scope
489 unQualOK (GRE {gre_prov = LocalDef}) = True
490 unQualOK (GRE {gre_prov = Imported is}) = any unQualSpecOK is
492 plusGlobalRdrEnv :: GlobalRdrEnv -> GlobalRdrEnv -> GlobalRdrEnv
493 plusGlobalRdrEnv env1 env2 = plusOccEnv_C (foldr insertGRE) env1 env2
495 mkGlobalRdrEnv :: [GlobalRdrElt] -> GlobalRdrEnv
497 = foldr add emptyGlobalRdrEnv gres
499 add gre env = extendOccEnv_C (foldr insertGRE) env
500 (nameOccName (gre_name gre))
503 findLocalDupsRdrEnv :: GlobalRdrEnv -> [OccName] -> (GlobalRdrEnv, [[Name]])
504 -- ^ For each 'OccName', see if there are multiple local definitions
505 -- for it. If so, remove all but one (to suppress subsequent error messages)
506 -- and return a list of the duplicate bindings
507 findLocalDupsRdrEnv rdr_env occs
510 go rdr_env dups [] = (rdr_env, dups)
511 go rdr_env dups (occ:occs)
512 = case filter isLocalGRE gres of
513 [] -> WARN( True, ppr occ <+> ppr rdr_env )
514 go rdr_env dups occs -- Weird! No binding for occ
515 [_] -> go rdr_env dups occs -- The common case
516 dup_gres -> go (extendOccEnv rdr_env occ (head dup_gres : nonlocal_gres))
517 (map gre_name dup_gres : dups)
520 gres = lookupOccEnv rdr_env occ `orElse` []
521 nonlocal_gres = filterOut isLocalGRE gres
524 insertGRE :: GlobalRdrElt -> [GlobalRdrElt] -> [GlobalRdrElt]
525 insertGRE new_g [] = [new_g]
526 insertGRE new_g (old_g : old_gs)
527 | gre_name new_g == gre_name old_g
528 = new_g `plusGRE` old_g : old_gs
530 = old_g : insertGRE new_g old_gs
532 plusGRE :: GlobalRdrElt -> GlobalRdrElt -> GlobalRdrElt
533 -- Used when the gre_name fields match
535 = GRE { gre_name = gre_name g1,
536 gre_prov = gre_prov g1 `plusProv` gre_prov g2,
537 gre_par = gre_par g1 `plusParent` gre_par g2 }
539 hideSomeUnquals :: GlobalRdrEnv -> [OccName] -> GlobalRdrEnv
540 -- ^ Hide any unqualified bindings for the specified OccNames
541 -- This is used in TH, when renaming a declaration bracket
543 -- > [d| foo = ... |]
545 -- We want unqualified @foo@ in "..." to mean this @foo@, not
546 -- the one from the enclosing module. But the /qualified/ name
547 -- from the enclosing module must certainly still be available
549 -- Seems like 5 times as much work as it deserves!
550 hideSomeUnquals rdr_env occs
551 = foldr hide rdr_env occs
554 | Just gres <- lookupOccEnv env occ = extendOccEnv env occ (map qual_gre gres)
556 qual_gre gre@(GRE { gre_name = name, gre_prov = LocalDef })
557 = gre { gre_prov = Imported [imp_spec] }
558 where -- Local defs get transfomed to (fake) imported things
559 mod = moduleName (nameModule name)
560 imp_spec = ImpSpec { is_item = ImpAll, is_decl = decl_spec }
561 decl_spec = ImpDeclSpec { is_mod = mod, is_as = mod,
563 is_dloc = srcLocSpan (nameSrcLoc name) }
565 qual_gre gre@(GRE { gre_prov = Imported specs })
566 = gre { gre_prov = Imported (map qual_spec specs) }
568 qual_spec spec@(ImpSpec { is_decl = decl_spec })
569 = spec { is_decl = decl_spec { is_qual = True } }
572 %************************************************************************
576 %************************************************************************
579 -- | The 'Provenance' of something says how it came to be in scope.
580 -- It's quite elaborate so that we can give accurate unused-name warnings.
582 = LocalDef -- ^ The thing was defined locally
584 [ImportSpec] -- ^ The thing was imported.
586 -- INVARIANT: the list of 'ImportSpec' is non-empty
588 data ImportSpec = ImpSpec { is_decl :: ImpDeclSpec,
589 is_item :: ImpItemSpec }
592 -- | Describes a particular import declaration and is
593 -- shared among all the 'Provenance's for that decl
596 is_mod :: ModuleName, -- ^ Module imported, e.g. @import Muggle@
597 -- Note the @Muggle@ may well not be
598 -- the defining module for this thing!
600 -- TODO: either should be Module, or there
601 -- should be a Maybe PackageId here too.
602 is_as :: ModuleName, -- ^ Import alias, e.g. from @as M@ (or @Muggle@ if there is no @as@ clause)
603 is_qual :: Bool, -- ^ Was this import qualified?
604 is_dloc :: SrcSpan -- ^ The location of the import declaration
607 -- | Describes import info a particular Name
609 = ImpAll -- ^ The import had no import list,
610 -- or had a hiding list
614 is_iloc :: SrcSpan -- Location of the import item
615 } -- ^ The import had an import list.
616 -- The 'is_explicit' field is @True@ iff the thing was named
617 -- /explicitly/ in the import specs rather
618 -- than being imported as part of a "..." group. Consider:
620 -- > import C( T(..) )
622 -- Here the constructors of @T@ are not named explicitly;
623 -- only @T@ is named explicitly.
625 unQualSpecOK :: ImportSpec -> Bool
626 -- ^ Is in scope unqualified?
627 unQualSpecOK is = not (is_qual (is_decl is))
629 qualSpecOK :: ModuleName -> ImportSpec -> Bool
630 -- ^ Is in scope qualified with the given module?
631 qualSpecOK mod is = mod == is_as (is_decl is)
633 importSpecLoc :: ImportSpec -> SrcSpan
634 importSpecLoc (ImpSpec decl ImpAll) = is_dloc decl
635 importSpecLoc (ImpSpec _ item) = is_iloc item
637 importSpecModule :: ImportSpec -> ModuleName
638 importSpecModule is = is_mod (is_decl is)
640 isExplicitItem :: ImpItemSpec -> Bool
641 isExplicitItem ImpAll = False
642 isExplicitItem (ImpSome {is_explicit = exp}) = exp
644 -- Note [Comparing provenance]
645 -- Comparison of provenance is just used for grouping
646 -- error messages (in RnEnv.warnUnusedBinds)
647 instance Eq Provenance where
648 p1 == p2 = case p1 `compare` p2 of EQ -> True; _ -> False
650 instance Eq ImpDeclSpec where
651 p1 == p2 = case p1 `compare` p2 of EQ -> True; _ -> False
653 instance Eq ImpItemSpec where
654 p1 == p2 = case p1 `compare` p2 of EQ -> True; _ -> False
656 instance Ord Provenance where
657 compare LocalDef LocalDef = EQ
658 compare LocalDef (Imported _) = LT
659 compare (Imported _ ) LocalDef = GT
660 compare (Imported is1) (Imported is2) = compare (head is1)
661 {- See Note [Comparing provenance] -} (head is2)
663 instance Ord ImpDeclSpec where
664 compare is1 is2 = (is_mod is1 `compare` is_mod is2) `thenCmp`
665 (is_dloc is1 `compare` is_dloc is2)
667 instance Ord ImpItemSpec where
668 compare is1 is2 = is_iloc is1 `compare` is_iloc is2
672 plusProv :: Provenance -> Provenance -> Provenance
673 -- Choose LocalDef over Imported
674 -- There is an obscure bug lurking here; in the presence
675 -- of recursive modules, something can be imported *and* locally
676 -- defined, and one might refer to it with a qualified name from
677 -- the import -- but I'm going to ignore that because it makes
678 -- the isLocalGRE predicate so much nicer this way
679 plusProv LocalDef LocalDef = panic "plusProv"
680 plusProv LocalDef _ = LocalDef
681 plusProv _ LocalDef = LocalDef
682 plusProv (Imported is1) (Imported is2) = Imported (is1++is2)
684 pprNameProvenance :: GlobalRdrElt -> SDoc
685 -- ^ Print out the place where the name was imported
686 pprNameProvenance (GRE {gre_name = name, gre_prov = LocalDef})
687 = ptext (sLit "defined at") <+> ppr (nameSrcLoc name)
688 pprNameProvenance (GRE {gre_name = name, gre_prov = Imported whys})
690 (why:_) -> sep [ppr why, nest 2 (ppr_defn (nameSrcLoc name))]
691 [] -> panic "pprNameProvenance"
693 -- If we know the exact definition point (which we may do with GHCi)
694 -- then show that too. But not if it's just "imported from X".
695 ppr_defn :: SrcLoc -> SDoc
696 ppr_defn loc | isGoodSrcLoc loc = parens (ptext (sLit "defined at") <+> ppr loc)
699 instance Outputable ImportSpec where
701 = ptext (sLit "imported from") <+> ppr (importSpecModule imp_spec)
702 <+> if isGoodSrcSpan loc then ptext (sLit "at") <+> ppr loc
705 loc = importSpecLoc imp_spec