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 = ASSERT( isExternalName n )
148 (setOccNameSpace ns (nameOccName n))
152 -- These two are the basic constructors
153 mkRdrUnqual :: OccName -> RdrName
154 mkRdrUnqual occ = Unqual occ
156 mkRdrQual :: ModuleName -> OccName -> RdrName
157 mkRdrQual mod occ = Qual mod occ
159 mkOrig :: Module -> OccName -> RdrName
160 mkOrig mod occ = Orig mod occ
163 -- | Produce an original 'RdrName' whose module that of a parent 'Name' but its 'OccName'
164 -- is derived from that of it's parent using the supplied function
165 mkDerivedRdrName :: Name -> (OccName -> OccName) -> RdrName
166 mkDerivedRdrName parent mk_occ
167 = ASSERT2( isExternalName parent, ppr parent )
168 mkOrig (nameModule parent) (mk_occ (nameOccName parent))
171 -- These two are used when parsing source files
172 -- They do encode the module and occurrence names
173 mkUnqual :: NameSpace -> FastString -> RdrName
174 mkUnqual sp n = Unqual (mkOccNameFS sp n)
176 mkVarUnqual :: FastString -> RdrName
177 mkVarUnqual n = Unqual (mkVarOccFS n)
179 -- | Make a qualified 'RdrName' in the given namespace and where the 'ModuleName' and
180 -- the 'OccName' are taken from the first and second elements of the tuple respectively
181 mkQual :: NameSpace -> (FastString, FastString) -> RdrName
182 mkQual sp (m, n) = Qual (mkModuleNameFS m) (mkOccNameFS sp n)
184 getRdrName :: NamedThing thing => thing -> RdrName
185 getRdrName name = nameRdrName (getName name)
187 nameRdrName :: Name -> RdrName
188 nameRdrName name = Exact name
189 -- Keep the Name even for Internal names, so that the
190 -- unique is still there for debug printing, particularly
191 -- of Types (which are converted to IfaceTypes before printing)
193 nukeExact :: Name -> RdrName
195 | isExternalName n = Orig (nameModule n) (nameOccName n)
196 | otherwise = Unqual (nameOccName n)
200 isRdrDataCon :: RdrName -> Bool
201 isRdrTyVar :: RdrName -> Bool
202 isRdrTc :: RdrName -> Bool
204 isRdrDataCon rn = isDataOcc (rdrNameOcc rn)
205 isRdrTyVar rn = isTvOcc (rdrNameOcc rn)
206 isRdrTc rn = isTcOcc (rdrNameOcc rn)
208 isSrcRdrName :: RdrName -> Bool
209 isSrcRdrName (Unqual _) = True
210 isSrcRdrName (Qual _ _) = True
211 isSrcRdrName _ = False
213 isUnqual :: RdrName -> Bool
214 isUnqual (Unqual _) = True
217 isQual :: RdrName -> Bool
218 isQual (Qual _ _) = True
221 isQual_maybe :: RdrName -> Maybe (ModuleName, OccName)
222 isQual_maybe (Qual m n) = Just (m,n)
223 isQual_maybe _ = Nothing
225 isOrig :: RdrName -> Bool
226 isOrig (Orig _ _) = True
229 isOrig_maybe :: RdrName -> Maybe (Module, OccName)
230 isOrig_maybe (Orig m n) = Just (m,n)
231 isOrig_maybe _ = Nothing
233 isExact :: RdrName -> Bool
234 isExact (Exact _) = True
237 isExact_maybe :: RdrName -> Maybe Name
238 isExact_maybe (Exact n) = Just n
239 isExact_maybe _ = Nothing
243 %************************************************************************
245 \subsection{Instances}
247 %************************************************************************
250 instance Outputable RdrName where
251 ppr (Exact name) = ppr name
252 ppr (Unqual occ) = ppr occ
253 ppr (Qual mod occ) = ppr mod <> dot <> ppr occ
254 ppr (Orig mod occ) = ppr mod <> dot <> ppr occ
256 instance OutputableBndr RdrName where
258 | isTvOcc (rdrNameOcc n) = char '@' <+> ppr n
261 showRdrName :: RdrName -> String
262 showRdrName r = showSDoc (ppr r)
264 instance Eq RdrName where
265 (Exact n1) == (Exact n2) = n1==n2
266 -- Convert exact to orig
267 (Exact n1) == r2@(Orig _ _) = nukeExact n1 == r2
268 r1@(Orig _ _) == (Exact n2) = r1 == nukeExact n2
270 (Orig m1 o1) == (Orig m2 o2) = m1==m2 && o1==o2
271 (Qual m1 o1) == (Qual m2 o2) = m1==m2 && o1==o2
272 (Unqual o1) == (Unqual o2) = o1==o2
275 instance Ord RdrName where
276 a <= b = case (a `compare` b) of { LT -> True; EQ -> True; GT -> False }
277 a < b = case (a `compare` b) of { LT -> True; EQ -> False; GT -> False }
278 a >= b = case (a `compare` b) of { LT -> False; EQ -> True; GT -> True }
279 a > b = case (a `compare` b) of { LT -> False; EQ -> False; GT -> True }
281 -- Exact < Unqual < Qual < Orig
282 -- [Note: Apr 2004] We used to use nukeExact to convert Exact to Orig
283 -- before comparing so that Prelude.map == the exact Prelude.map, but
284 -- that meant that we reported duplicates when renaming bindings
285 -- generated by Template Haskell; e.g
286 -- do { n1 <- newName "foo"; n2 <- newName "foo";
287 -- <decl involving n1,n2> }
288 -- I think we can do without this conversion
289 compare (Exact n1) (Exact n2) = n1 `compare` n2
290 compare (Exact _) _ = LT
292 compare (Unqual _) (Exact _) = GT
293 compare (Unqual o1) (Unqual o2) = o1 `compare` o2
294 compare (Unqual _) _ = LT
296 compare (Qual _ _) (Exact _) = GT
297 compare (Qual _ _) (Unqual _) = GT
298 compare (Qual m1 o1) (Qual m2 o2) = (o1 `compare` o2) `thenCmp` (m1 `compare` m2)
299 compare (Qual _ _) (Orig _ _) = LT
301 compare (Orig m1 o1) (Orig m2 o2) = (o1 `compare` o2) `thenCmp` (m1 `compare` m2)
302 compare (Orig _ _) _ = GT
305 %************************************************************************
309 %************************************************************************
312 -- | This environment is used to store local bindings (@let@, @where@, lambda, @case@).
313 -- It is keyed by OccName, because we never use it for qualified names
314 type LocalRdrEnv = OccEnv Name
316 emptyLocalRdrEnv :: LocalRdrEnv
317 emptyLocalRdrEnv = emptyOccEnv
319 extendLocalRdrEnv :: LocalRdrEnv -> [Name] -> LocalRdrEnv
320 extendLocalRdrEnv env names
321 = extendOccEnvList env [(nameOccName n, n) | n <- names]
323 lookupLocalRdrEnv :: LocalRdrEnv -> RdrName -> Maybe Name
324 lookupLocalRdrEnv _ (Exact name) = Just name
325 lookupLocalRdrEnv env (Unqual occ) = lookupOccEnv env occ
326 lookupLocalRdrEnv _ _ = Nothing
328 lookupLocalRdrOcc :: LocalRdrEnv -> OccName -> Maybe Name
329 lookupLocalRdrOcc env occ = lookupOccEnv env occ
331 elemLocalRdrEnv :: RdrName -> LocalRdrEnv -> Bool
332 elemLocalRdrEnv rdr_name env
333 | isUnqual rdr_name = rdrNameOcc rdr_name `elemOccEnv` env
337 %************************************************************************
341 %************************************************************************
344 type GlobalRdrEnv = OccEnv [GlobalRdrElt]
345 -- ^ Keyed by 'OccName'; when looking up a qualified name
346 -- we look up the 'OccName' part, and then check the 'Provenance'
347 -- to see if the appropriate qualification is valid. This
348 -- saves routinely doubling the size of the env by adding both
349 -- qualified and unqualified names to the domain.
351 -- The list in the codomain is required because there may be name clashes
352 -- These only get reported on lookup, not on construction
354 -- INVARIANT: All the members of the list have distinct
355 -- 'gre_name' fields; that is, no duplicate Names
357 -- | An element of the 'GlobalRdrEnv'
359 = GRE { gre_name :: Name,
361 gre_prov :: Provenance -- ^ Why it's in scope
364 data Parent = NoParent | ParentIs Name
367 instance Outputable Parent where
369 ppr (ParentIs n) = ptext (sLit "parent:") <> ppr n
372 plusParent :: Parent -> Parent -> Parent
373 plusParent p1 p2 = ASSERT2( p1 == p2, parens (ppr p1) <+> parens (ppr p2) )
376 {- Why so complicated? -=chak
377 plusParent :: Parent -> Parent -> Parent
378 plusParent NoParent rel =
379 ASSERT2( case rel of { NoParent -> True; other -> False },
380 ptext (sLit "plusParent[NoParent]: ") <+> ppr rel )
382 plusParent (ParentIs n) rel =
383 ASSERT2( case rel of { ParentIs m -> n==m; other -> False },
384 ptext (sLit "plusParent[ParentIs]:") <+> ppr n <> comma <+> ppr rel )
388 emptyGlobalRdrEnv :: GlobalRdrEnv
389 emptyGlobalRdrEnv = emptyOccEnv
391 globalRdrEnvElts :: GlobalRdrEnv -> [GlobalRdrElt]
392 globalRdrEnvElts env = foldOccEnv (++) [] env
394 instance Outputable GlobalRdrElt where
395 ppr gre = ppr name <+> parens (ppr (gre_par gre) <+> pprNameProvenance gre)
399 pprGlobalRdrEnv :: GlobalRdrEnv -> SDoc
401 = vcat (map pp (occEnvElts env))
403 pp gres = ppr (nameOccName (gre_name (head gres))) <> colon <+>
404 vcat [ ppr (gre_name gre) <+> pprNameProvenance gre
409 lookupGlobalRdrEnv :: GlobalRdrEnv -> OccName -> [GlobalRdrElt]
410 lookupGlobalRdrEnv env occ_name = case lookupOccEnv env occ_name of
414 extendGlobalRdrEnv :: GlobalRdrEnv -> GlobalRdrElt -> GlobalRdrEnv
415 extendGlobalRdrEnv env gre = extendOccEnv_C add env occ [gre]
417 occ = nameOccName (gre_name gre)
418 add gres _ = gre:gres
420 lookupGRE_RdrName :: RdrName -> GlobalRdrEnv -> [GlobalRdrElt]
421 lookupGRE_RdrName rdr_name env
422 = case lookupOccEnv env (rdrNameOcc rdr_name) of
424 Just gres -> pickGREs rdr_name gres
426 lookupGRE_Name :: GlobalRdrEnv -> Name -> [GlobalRdrElt]
427 lookupGRE_Name env name
428 = [ gre | gre <- lookupGlobalRdrEnv env (nameOccName name),
429 gre_name gre == name ]
431 getGRE_NameQualifier_maybes :: GlobalRdrEnv -> Name -> [Maybe [ModuleName]]
432 getGRE_NameQualifier_maybes env
433 = map qualifier_maybe . map gre_prov . lookupGRE_Name env
434 where qualifier_maybe LocalDef = Nothing
435 qualifier_maybe (Imported iss) = Just $ map (is_as . is_decl) iss
437 pickGREs :: RdrName -> [GlobalRdrElt] -> [GlobalRdrElt]
438 -- ^ Take a list of GREs which have the right OccName
439 -- Pick those GREs that are suitable for this RdrName
440 -- And for those, keep only only the Provenances that are suitable
445 -- module A ( f ) where
446 -- import qualified Foo( f )
451 -- Let's suppose that @Foo.f@ and @Baz.f@ are the same entity really.
452 -- The export of @f@ is ambiguous because it's in scope from the local def
453 -- and the import. The lookup of @Unqual f@ should return a GRE for
454 -- the locally-defined @f@, and a GRE for the imported @f@, with a /single/
455 -- provenance, namely the one for @Baz(f)@.
456 pickGREs rdr_name gres
457 = mapCatMaybes pick gres
459 rdr_is_unqual = isUnqual rdr_name
460 rdr_is_qual = isQual_maybe rdr_name
462 pick :: GlobalRdrElt -> Maybe GlobalRdrElt
463 pick gre@(GRE {gre_prov = LocalDef, gre_name = n}) -- Local def
464 | rdr_is_unqual = Just gre
465 | Just (mod,_) <- rdr_is_qual,
466 mod == moduleName (nameModule n) = Just gre
467 | otherwise = Nothing
468 pick gre@(GRE {gre_prov = Imported [is]}) -- Single import (efficiency)
470 not (is_qual (is_decl is)) = Just gre
471 | Just (mod,_) <- rdr_is_qual,
472 mod == is_as (is_decl is) = Just gre
473 | otherwise = Nothing
474 pick gre@(GRE {gre_prov = Imported is}) -- Multiple import
475 | null filtered_is = Nothing
476 | otherwise = Just (gre {gre_prov = Imported filtered_is})
478 filtered_is | rdr_is_unqual
479 = filter (not . is_qual . is_decl) is
480 | Just (mod,_) <- rdr_is_qual
481 = filter ((== mod) . is_as . is_decl) is
485 isLocalGRE :: GlobalRdrElt -> Bool
486 isLocalGRE (GRE {gre_prov = LocalDef}) = True
489 unQualOK :: GlobalRdrElt -> Bool
490 -- ^ Test if an unqualifed version of this thing would be in scope
491 unQualOK (GRE {gre_prov = LocalDef}) = True
492 unQualOK (GRE {gre_prov = Imported is}) = any unQualSpecOK is
494 plusGlobalRdrEnv :: GlobalRdrEnv -> GlobalRdrEnv -> GlobalRdrEnv
495 plusGlobalRdrEnv env1 env2 = plusOccEnv_C (foldr insertGRE) env1 env2
497 mkGlobalRdrEnv :: [GlobalRdrElt] -> GlobalRdrEnv
499 = foldr add emptyGlobalRdrEnv gres
501 add gre env = extendOccEnv_C (foldr insertGRE) env
502 (nameOccName (gre_name gre))
505 findLocalDupsRdrEnv :: GlobalRdrEnv -> [OccName] -> (GlobalRdrEnv, [[Name]])
506 -- ^ For each 'OccName', see if there are multiple local definitions
507 -- for it. If so, remove all but one (to suppress subsequent error messages)
508 -- and return a list of the duplicate bindings
509 findLocalDupsRdrEnv rdr_env occs
512 go rdr_env dups [] = (rdr_env, dups)
513 go rdr_env dups (occ:occs)
514 = case filter isLocalGRE gres of
515 [] -> WARN( True, ppr occ <+> ppr rdr_env )
516 go rdr_env dups occs -- Weird! No binding for occ
517 [_] -> go rdr_env dups occs -- The common case
518 dup_gres -> go (extendOccEnv rdr_env occ (head dup_gres : nonlocal_gres))
519 (map gre_name dup_gres : dups)
522 gres = lookupOccEnv rdr_env occ `orElse` []
523 nonlocal_gres = filterOut isLocalGRE gres
526 insertGRE :: GlobalRdrElt -> [GlobalRdrElt] -> [GlobalRdrElt]
527 insertGRE new_g [] = [new_g]
528 insertGRE new_g (old_g : old_gs)
529 | gre_name new_g == gre_name old_g
530 = new_g `plusGRE` old_g : old_gs
532 = old_g : insertGRE new_g old_gs
534 plusGRE :: GlobalRdrElt -> GlobalRdrElt -> GlobalRdrElt
535 -- Used when the gre_name fields match
537 = GRE { gre_name = gre_name g1,
538 gre_prov = gre_prov g1 `plusProv` gre_prov g2,
539 gre_par = gre_par g1 `plusParent` gre_par g2 }
541 hideSomeUnquals :: GlobalRdrEnv -> [OccName] -> GlobalRdrEnv
542 -- ^ Hide any unqualified bindings for the specified OccNames
543 -- This is used in TH, when renaming a declaration bracket
545 -- > [d| foo = ... |]
547 -- We want unqualified @foo@ in "..." to mean this @foo@, not
548 -- the one from the enclosing module. But the /qualified/ name
549 -- from the enclosing module must certainly still be available
551 -- Seems like 5 times as much work as it deserves!
552 hideSomeUnquals rdr_env occs
553 = foldr hide rdr_env occs
556 | Just gres <- lookupOccEnv env occ = extendOccEnv env occ (map qual_gre gres)
558 qual_gre gre@(GRE { gre_name = name, gre_prov = LocalDef })
559 = gre { gre_prov = Imported [imp_spec] }
560 where -- Local defs get transfomed to (fake) imported things
561 mod = ASSERT2( isExternalName name, ppr name) moduleName (nameModule name)
562 imp_spec = ImpSpec { is_item = ImpAll, is_decl = decl_spec }
563 decl_spec = ImpDeclSpec { is_mod = mod, is_as = mod,
565 is_dloc = srcLocSpan (nameSrcLoc name) }
567 qual_gre gre@(GRE { gre_prov = Imported specs })
568 = gre { gre_prov = Imported (map qual_spec specs) }
570 qual_spec spec@(ImpSpec { is_decl = decl_spec })
571 = spec { is_decl = decl_spec { is_qual = True } }
574 %************************************************************************
578 %************************************************************************
581 -- | The 'Provenance' of something says how it came to be in scope.
582 -- It's quite elaborate so that we can give accurate unused-name warnings.
584 = LocalDef -- ^ The thing was defined locally
586 [ImportSpec] -- ^ The thing was imported.
588 -- INVARIANT: the list of 'ImportSpec' is non-empty
590 data ImportSpec = ImpSpec { is_decl :: ImpDeclSpec,
591 is_item :: ImpItemSpec }
594 -- | Describes a particular import declaration and is
595 -- shared among all the 'Provenance's for that decl
598 is_mod :: ModuleName, -- ^ Module imported, e.g. @import Muggle@
599 -- Note the @Muggle@ may well not be
600 -- the defining module for this thing!
602 -- TODO: either should be Module, or there
603 -- should be a Maybe PackageId here too.
604 is_as :: ModuleName, -- ^ Import alias, e.g. from @as M@ (or @Muggle@ if there is no @as@ clause)
605 is_qual :: Bool, -- ^ Was this import qualified?
606 is_dloc :: SrcSpan -- ^ The location of the import declaration
609 -- | Describes import info a particular Name
611 = ImpAll -- ^ The import had no import list,
612 -- or had a hiding list
616 is_iloc :: SrcSpan -- Location of the import item
617 } -- ^ The import had an import list.
618 -- The 'is_explicit' field is @True@ iff the thing was named
619 -- /explicitly/ in the import specs rather
620 -- than being imported as part of a "..." group. Consider:
622 -- > import C( T(..) )
624 -- Here the constructors of @T@ are not named explicitly;
625 -- only @T@ is named explicitly.
627 unQualSpecOK :: ImportSpec -> Bool
628 -- ^ Is in scope unqualified?
629 unQualSpecOK is = not (is_qual (is_decl is))
631 qualSpecOK :: ModuleName -> ImportSpec -> Bool
632 -- ^ Is in scope qualified with the given module?
633 qualSpecOK mod is = mod == is_as (is_decl is)
635 importSpecLoc :: ImportSpec -> SrcSpan
636 importSpecLoc (ImpSpec decl ImpAll) = is_dloc decl
637 importSpecLoc (ImpSpec _ item) = is_iloc item
639 importSpecModule :: ImportSpec -> ModuleName
640 importSpecModule is = is_mod (is_decl is)
642 isExplicitItem :: ImpItemSpec -> Bool
643 isExplicitItem ImpAll = False
644 isExplicitItem (ImpSome {is_explicit = exp}) = exp
646 -- Note [Comparing provenance]
647 -- Comparison of provenance is just used for grouping
648 -- error messages (in RnEnv.warnUnusedBinds)
649 instance Eq Provenance where
650 p1 == p2 = case p1 `compare` p2 of EQ -> True; _ -> False
652 instance Eq ImpDeclSpec where
653 p1 == p2 = case p1 `compare` p2 of EQ -> True; _ -> False
655 instance Eq ImpItemSpec where
656 p1 == p2 = case p1 `compare` p2 of EQ -> True; _ -> False
658 instance Ord Provenance where
659 compare LocalDef LocalDef = EQ
660 compare LocalDef (Imported _) = LT
661 compare (Imported _ ) LocalDef = GT
662 compare (Imported is1) (Imported is2) = compare (head is1)
663 {- See Note [Comparing provenance] -} (head is2)
665 instance Ord ImpDeclSpec where
666 compare is1 is2 = (is_mod is1 `compare` is_mod is2) `thenCmp`
667 (is_dloc is1 `compare` is_dloc is2)
669 instance Ord ImpItemSpec where
670 compare is1 is2 = is_iloc is1 `compare` is_iloc is2
674 plusProv :: Provenance -> Provenance -> Provenance
675 -- Choose LocalDef over Imported
676 -- There is an obscure bug lurking here; in the presence
677 -- of recursive modules, something can be imported *and* locally
678 -- defined, and one might refer to it with a qualified name from
679 -- the import -- but I'm going to ignore that because it makes
680 -- the isLocalGRE predicate so much nicer this way
681 plusProv LocalDef LocalDef = panic "plusProv"
682 plusProv LocalDef _ = LocalDef
683 plusProv _ LocalDef = LocalDef
684 plusProv (Imported is1) (Imported is2) = Imported (is1++is2)
686 pprNameProvenance :: GlobalRdrElt -> SDoc
687 -- ^ Print out the place where the name was imported
688 pprNameProvenance (GRE {gre_name = name, gre_prov = LocalDef})
689 = ptext (sLit "defined at") <+> ppr (nameSrcLoc name)
690 pprNameProvenance (GRE {gre_name = name, gre_prov = Imported whys})
692 (why:_) -> sep [ppr why, nest 2 (ppr_defn (nameSrcLoc name))]
693 [] -> panic "pprNameProvenance"
695 -- If we know the exact definition point (which we may do with GHCi)
696 -- then show that too. But not if it's just "imported from X".
697 ppr_defn :: SrcLoc -> SDoc
698 ppr_defn loc | isGoodSrcLoc loc = parens (ptext (sLit "defined at") <+> ppr loc)
701 instance Outputable ImportSpec where
703 = ptext (sLit "imported from") <+> ppr (importSpecModule imp_spec)
704 <+> if isGoodSrcSpan loc then ptext (sLit "at") <+> ppr loc
707 loc = importSpecLoc imp_spec