3 TyThing(..), TcTyThing(..), TcId,
5 -- Instance environment, and InstInfo type
6 InstInfo(..), iDFunId, pprInstInfo, pprInstInfoDetails,
7 simpleInstInfoClsTy, simpleInstInfoTy, simpleInstInfoTyCon,
13 tcLookupLocatedGlobal, tcLookupGlobal,
14 tcLookupGlobalId, tcLookupTyCon, tcLookupClass, tcLookupDataCon,
15 tcLookupLocatedGlobalId, tcLookupLocatedTyCon,
20 tcExtendTyVarEnv, tcExtendTyVarEnv2,
21 tcExtendIdEnv, tcExtendIdEnv1, tcExtendIdEnv2,
22 tcLookup, tcLookupLocated, tcLookupLocalIds,
23 tcLookupId, tcLookupTyVar,
24 lclEnvElts, getInLocalScope, findGlobals,
25 wrongThingErr, pprBinders,
27 tcExtendRecEnv, -- For knot-tying
32 -- Global type variables
35 -- Template Haskell stuff
36 checkWellStaged, spliceOK, bracketOK, tcMetaTy, thLevel,
40 newLocalName, newDFunName
43 #include "HsVersions.h"
45 import HsSyn ( LRuleDecl, LHsBinds, LSig, pprLHsBinds )
46 import TcIface ( tcImportDecl )
47 import IfaceEnv ( newGlobalBinder )
48 import TcRnTypes ( pprTcTyThingCategory )
50 import TcMType ( zonkTcType, zonkTcTyVarsAndFV )
51 import TcType ( Type, TcKind, TcTyVar, TcTyVarSet, TcType,
52 tyVarsOfType, tyVarsOfTypes, mkGenTyConApp,
53 getDFunTyKey, tcTyConAppTyCon, tcGetTyVar, mkTyVarTy,
56 import qualified Type ( getTyVar_maybe )
57 import Id ( idName, isLocalId )
58 import Var ( TyVar, Id, idType, tyVarName )
61 import RdrName ( extendLocalRdrEnv )
62 import InstEnv ( Instance, DFunId, instanceDFunId, instanceHead )
63 import DataCon ( DataCon )
64 import TyCon ( TyCon )
65 import Class ( Class )
66 import Name ( Name, NamedThing(..), getSrcLoc, mkInternalName, nameIsLocalOrFrom )
68 import OccName ( mkDFunOcc, occNameString )
69 import HscTypes ( extendTypeEnvList, lookupType,
70 TyThing(..), tyThingId, tyThingDataCon,
71 ExternalPackageState(..) )
73 import SrcLoc ( SrcLoc, Located(..) )
78 %************************************************************************
82 %************************************************************************
84 Using the Located versions (eg. tcLookupLocatedGlobal) is preferred,
85 unless you know that the SrcSpan in the monad is already set to the
89 tcLookupLocatedGlobal :: Located Name -> TcM TyThing
90 -- c.f. IfaceEnvEnv.tcIfaceGlobal
91 tcLookupLocatedGlobal name
92 = addLocM tcLookupGlobal name
94 tcLookupGlobal :: Name -> TcM TyThing
96 = do { env <- getGblEnv
97 ; if nameIsLocalOrFrom (tcg_mod env) name
99 then -- It's defined in this module
100 case lookupNameEnv (tcg_type_env env) name of
101 Just thing -> return thing
102 Nothing -> notFound name -- Panic!
104 else do -- It's imported
105 { (eps,hpt) <- getEpsAndHpt
106 ; case lookupType hpt (eps_PTE eps) name of
107 Just thing -> return thing
108 Nothing -> tcImportDecl name
111 tcLookupGlobalId :: Name -> TcM Id
112 -- Never used for Haskell-source DataCons, hence no ADataCon case
113 tcLookupGlobalId name
114 = tcLookupGlobal name `thenM` \ thing ->
115 return (tyThingId thing)
117 tcLookupDataCon :: Name -> TcM DataCon
118 tcLookupDataCon con_name
119 = tcLookupGlobal con_name `thenM` \ thing ->
120 return (tyThingDataCon thing)
122 tcLookupClass :: Name -> TcM Class
124 = tcLookupGlobal name `thenM` \ thing ->
126 AClass cls -> return cls
127 other -> wrongThingErr "class" (AGlobal thing) name
129 tcLookupTyCon :: Name -> TcM TyCon
131 = tcLookupGlobal name `thenM` \ thing ->
133 ATyCon tc -> return tc
134 other -> wrongThingErr "type constructor" (AGlobal thing) name
136 tcLookupLocatedGlobalId :: Located Name -> TcM Id
137 tcLookupLocatedGlobalId = addLocM tcLookupId
139 tcLookupLocatedClass :: Located Name -> TcM Class
140 tcLookupLocatedClass = addLocM tcLookupClass
142 tcLookupLocatedTyCon :: Located Name -> TcM TyCon
143 tcLookupLocatedTyCon = addLocM tcLookupTyCon
146 %************************************************************************
148 Extending the global environment
150 %************************************************************************
154 tcExtendGlobalEnv :: [TyThing] -> TcM r -> TcM r
155 -- Given a mixture of Ids, TyCons, Classes, all from the
156 -- module being compiled, extend the global environment
157 tcExtendGlobalEnv things thing_inside
158 = do { env <- getGblEnv
159 ; let ge' = extendTypeEnvList (tcg_type_env env) things
160 ; setGblEnv (env {tcg_type_env = ge'}) thing_inside }
162 tcExtendGlobalValEnv :: [Id] -> TcM a -> TcM a
163 -- Same deal as tcExtendGlobalEnv, but for Ids
164 tcExtendGlobalValEnv ids thing_inside
165 = tcExtendGlobalEnv [AnId id | id <- ids] thing_inside
169 tcExtendRecEnv :: [(Name,TyThing)] -> TcM r -> TcM r
170 -- Extend the global environments for the type/class knot tying game
171 tcExtendRecEnv gbl_stuff thing_inside
172 = updGblEnv upd thing_inside
174 upd env = env { tcg_type_env = extend (tcg_type_env env) }
175 extend env = extendNameEnvList env gbl_stuff
179 %************************************************************************
181 \subsection{The local environment}
183 %************************************************************************
186 tcLookupLocated :: Located Name -> TcM TcTyThing
187 tcLookupLocated = addLocM tcLookup
189 tcLookup :: Name -> TcM TcTyThing
191 = getLclEnv `thenM` \ local_env ->
192 case lookupNameEnv (tcl_env local_env) name of
193 Just thing -> returnM thing
194 Nothing -> tcLookupGlobal name `thenM` \ thing ->
195 returnM (AGlobal thing)
197 tcLookupTyVar :: Name -> TcM TcTyVar
199 = tcLookup name `thenM` \ thing ->
201 ATyVar _ ty -> returnM (tcGetTyVar "tcLookupTyVar" ty)
202 other -> pprPanic "tcLookupTyVar" (ppr name)
204 tcLookupId :: Name -> TcM Id
205 -- Used when we aren't interested in the binding level
206 -- Never a DataCon. (Why does that matter? see TcExpr.tcId)
208 = tcLookup name `thenM` \ thing ->
210 ATcId tc_id _ -> returnM tc_id
211 AGlobal (AnId id) -> returnM id
212 other -> pprPanic "tcLookupId" (ppr name)
214 tcLookupLocalIds :: [Name] -> TcM [TcId]
215 -- We expect the variables to all be bound, and all at
216 -- the same level as the lookup. Only used in one place...
218 = getLclEnv `thenM` \ env ->
219 returnM (map (lookup (tcl_env env) (thLevel (tcl_th_ctxt env))) ns)
222 = case lookupNameEnv lenv name of
223 Just (ATcId id lvl1) -> ASSERT( lvl == lvl1 ) id
224 other -> pprPanic "tcLookupLocalIds" (ppr name)
226 lclEnvElts :: TcLclEnv -> [TcTyThing]
227 lclEnvElts env = nameEnvElts (tcl_env env)
229 getInLocalScope :: TcM (Name -> Bool)
231 getInLocalScope = getLclEnv `thenM` \ env ->
233 lcl_env = tcl_env env
235 return (`elemNameEnv` lcl_env)
239 tcExtendKindEnv :: [(Name, TcKind)] -> TcM r -> TcM r
240 tcExtendKindEnv things thing_inside
241 = updLclEnv upd thing_inside
243 upd lcl_env = lcl_env { tcl_env = extend (tcl_env lcl_env) }
244 extend env = extendNameEnvList env [(n, AThing k) | (n,k) <- things]
246 tcExtendTyVarEnv :: [TyVar] -> TcM r -> TcM r
247 tcExtendTyVarEnv tvs thing_inside
248 = tcExtendTyVarEnv2 [(tyVarName tv, mkTyVarTy tv) | tv <- tvs] thing_inside
250 tcExtendTyVarEnv2 :: [(Name,TcType)] -> TcM r -> TcM r
251 tcExtendTyVarEnv2 binds thing_inside
252 = getLclEnv `thenM` \ env@(TcLclEnv {tcl_env = le,
254 tcl_rdr = rdr_env}) ->
256 rdr_env' = extendLocalRdrEnv rdr_env (map fst binds)
257 new_tv_set = tyVarsOfTypes (map snd binds)
258 le' = extendNameEnvList le [(name, ATyVar name ty) | (name, ty) <- binds]
260 -- It's important to add the in-scope tyvars to the global tyvar set
262 -- f (_::r) = let g y = y::r in ...
263 -- Here, g mustn't be generalised. This is also important during
264 -- class and instance decls, when we mustn't generalise the class tyvars
265 -- when typechecking the methods.
266 tc_extend_gtvs gtvs new_tv_set `thenM` \ gtvs' ->
267 setLclEnv (env {tcl_env = le', tcl_tyvars = gtvs', tcl_rdr = rdr_env'}) thing_inside
272 tcExtendIdEnv :: [TcId] -> TcM a -> TcM a
273 -- Invariant: the TcIds are fully zonked. Reasons:
274 -- (a) The kinds of the forall'd type variables are defaulted
275 -- (see Kind.defaultKind, done in zonkQuantifiedTyVar)
276 -- (b) There are no via-Indirect occurrences of the bound variables
277 -- in the types, because instantiation does not look through such things
278 -- (c) The call to tyVarsOfTypes is ok without looking through refs
279 tcExtendIdEnv ids thing_inside = tcExtendIdEnv2 [(idName id, id) | id <- ids] thing_inside
281 tcExtendIdEnv1 :: Name -> TcId -> TcM a -> TcM a
282 tcExtendIdEnv1 name id thing_inside = tcExtendIdEnv2 [(name,id)] thing_inside
284 tcExtendIdEnv2 :: [(Name,TcId)] -> TcM a -> TcM a
285 -- Invariant: the TcIds are fully zonked (see tcExtendIdEnv above)
286 tcExtendIdEnv2 names_w_ids thing_inside
287 = getLclEnv `thenM` \ env ->
289 extra_global_tyvars = tyVarsOfTypes [idType id | (name,id) <- names_w_ids]
290 th_lvl = thLevel (tcl_th_ctxt env)
291 extra_env = [(name, ATcId id th_lvl) | (name,id) <- names_w_ids]
292 le' = extendNameEnvList (tcl_env env) extra_env
293 rdr_env' = extendLocalRdrEnv (tcl_rdr env) (map fst names_w_ids)
295 tc_extend_gtvs (tcl_tyvars env) extra_global_tyvars `thenM` \ gtvs' ->
296 setLclEnv (env {tcl_env = le', tcl_tyvars = gtvs', tcl_rdr = rdr_env'}) thing_inside
301 -----------------------
302 -- findGlobals looks at the value environment and finds values
303 -- whose types mention the offending type variable. It has to be
304 -- careful to zonk the Id's type first, so it has to be in the monad.
305 -- We must be careful to pass it a zonked type variable, too.
307 findGlobals :: TcTyVarSet
309 -> TcM (TidyEnv, [SDoc])
311 findGlobals tvs tidy_env
312 = getLclEnv `thenM` \ lcl_env ->
313 go tidy_env [] (lclEnvElts lcl_env)
315 go tidy_env acc [] = returnM (tidy_env, acc)
316 go tidy_env acc (thing : things)
317 = find_thing ignore_it tidy_env thing `thenM` \ (tidy_env1, maybe_doc) ->
319 Just d -> go tidy_env1 (d:acc) things
320 Nothing -> go tidy_env1 acc things
322 ignore_it ty = not (tvs `intersectsVarSet` tyVarsOfType ty)
324 -----------------------
325 find_thing ignore_it tidy_env (ATcId id _)
326 = zonkTcType (idType id) `thenM` \ id_ty ->
327 if ignore_it id_ty then
328 returnM (tidy_env, Nothing)
330 (tidy_env', tidy_ty) = tidyOpenType tidy_env id_ty
331 msg = sep [ppr id <+> dcolon <+> ppr tidy_ty,
332 nest 2 (parens (ptext SLIT("bound at") <+>
333 ppr (getSrcLoc id)))]
335 returnM (tidy_env', Just msg)
337 find_thing ignore_it tidy_env (ATyVar tv ty)
338 = zonkTcType ty `thenM` \ tv_ty ->
339 if ignore_it tv_ty then
340 returnM (tidy_env, Nothing)
342 -- The name tv is scoped, so we don't need to tidy it
343 (tidy_env1, tidy_ty) = tidyOpenType tidy_env tv_ty
344 msg = sep [ptext SLIT("Scoped type variable") <+> quotes (ppr tv) <+> eq_stuff, nest 2 bound_at]
346 eq_stuff | Just tv' <- Type.getTyVar_maybe tv_ty,
347 getOccName tv == getOccName tv' = empty
348 | otherwise = equals <+> ppr tidy_ty
349 -- It's ok to use Type.getTyVar_maybe because ty is zonked by now
350 bound_at = parens $ ptext SLIT("bound at:") <+> ppr (getSrcLoc tv)
352 returnM (tidy_env1, Just msg)
356 %************************************************************************
358 \subsection{The global tyvars}
360 %************************************************************************
363 tc_extend_gtvs gtvs extra_global_tvs
364 = readMutVar gtvs `thenM` \ global_tvs ->
365 newMutVar (global_tvs `unionVarSet` extra_global_tvs)
368 @tcGetGlobalTyVars@ returns a fully-zonked set of tyvars free in the environment.
369 To improve subsequent calls to the same function it writes the zonked set back into
373 tcGetGlobalTyVars :: TcM TcTyVarSet
375 = getLclEnv `thenM` \ (TcLclEnv {tcl_tyvars = gtv_var}) ->
376 readMutVar gtv_var `thenM` \ gbl_tvs ->
377 zonkTcTyVarsAndFV (varSetElems gbl_tvs) `thenM` \ gbl_tvs' ->
378 writeMutVar gtv_var gbl_tvs' `thenM_`
383 %************************************************************************
387 %************************************************************************
390 tcExtendRules :: [LRuleDecl Id] -> TcM a -> TcM a
391 -- Just pop the new rules into the EPS and envt resp
392 -- All the rules come from an interface file, not soruce
393 -- Nevertheless, some may be for this module, if we read
394 -- its interface instead of its source code
395 tcExtendRules lcl_rules thing_inside
396 = do { env <- getGblEnv
398 env' = env { tcg_rules = lcl_rules ++ tcg_rules env }
399 ; setGblEnv env' thing_inside }
403 %************************************************************************
407 %************************************************************************
410 instance Outputable ThStage where
411 ppr Comp = text "Comp"
412 ppr (Brack l _ _) = text "Brack" <+> int l
413 ppr (Splice l) = text "Splice" <+> int l
416 thLevel :: ThStage -> ThLevel
417 thLevel Comp = topLevel
418 thLevel (Splice l) = l
419 thLevel (Brack l _ _) = l
422 checkWellStaged :: SDoc -- What the stage check is for
423 -> ThLevel -- Binding level
424 -> ThStage -- Use stage
425 -> TcM () -- Fail if badly staged, adding an error
426 checkWellStaged pp_thing bind_lvl use_stage
427 | bind_lvl <= use_lvl -- OK!
430 | bind_lvl == topLevel -- GHC restriction on top level splices
432 sep [ptext SLIT("GHC stage restriction:") <+> pp_thing,
433 nest 2 (ptext SLIT("is used in a top-level splice, and must be imported, not defined locally"))]
435 | otherwise -- Badly staged
437 ptext SLIT("Stage error:") <+> pp_thing <+>
438 hsep [ptext SLIT("is bound at stage") <+> ppr bind_lvl,
439 ptext SLIT("but used at stage") <+> ppr use_lvl]
441 use_lvl = thLevel use_stage
444 topIdLvl :: Id -> ThLevel
445 -- Globals may either be imported, or may be from an earlier "chunk"
446 -- (separated by declaration splices) of this module. The former
447 -- *can* be used inside a top-level splice, but the latter cannot.
448 -- Hence we give the former impLevel, but the latter topLevel
452 -- By the time we are prcessing the $(f x), the binding for "x"
453 -- will be in the global env, not the local one.
454 topIdLvl id | isLocalId id = topLevel
455 | otherwise = impLevel
457 -- Indicates the legal transitions on bracket( [| |] ).
458 bracketOK :: ThStage -> Maybe ThLevel
459 bracketOK (Brack _ _ _) = Nothing -- Bracket illegal inside a bracket
460 bracketOK stage = Just (thLevel stage + 1)
462 -- Indicates the legal transitions on splice($).
463 spliceOK :: ThStage -> Maybe ThLevel
464 spliceOK (Splice _) = Nothing -- Splice illegal inside splice
465 spliceOK stage = Just (thLevel stage - 1)
467 tcMetaTy :: Name -> TcM Type
468 -- Given the name of a Template Haskell data type,
470 -- E.g. given the name "Expr" return the type "Expr"
472 = tcLookupTyCon tc_name `thenM` \ t ->
473 returnM (mkGenTyConApp t [])
474 -- Use mkGenTyConApp because it might be a synonym
478 %************************************************************************
480 \subsection{Making new Ids}
482 %************************************************************************
487 newLocalName :: Name -> TcM Name
488 newLocalName name -- Make a clone
489 = newUnique `thenM` \ uniq ->
490 returnM (mkInternalName uniq (getOccName name) (getSrcLoc name))
493 Make a name for the dict fun for an instance decl. It's an *external*
494 name, like otber top-level names, and hence must be made with newGlobalBinder.
497 newDFunName :: Class -> [Type] -> SrcLoc -> TcM Name
498 newDFunName clas (ty:_) loc
499 = do { index <- nextDFunIndex
500 ; is_boot <- tcIsHsBoot
502 ; let info_string = occNameString (getOccName clas) ++
503 occNameString (getDFunTyKey ty)
504 dfun_occ = mkDFunOcc info_string is_boot index
506 ; newGlobalBinder mod dfun_occ Nothing loc }
508 newDFunName clas [] loc = pprPanic "newDFunName" (ppr clas <+> ppr loc)
512 %************************************************************************
514 \subsection{The InstInfo type}
516 %************************************************************************
518 The InstInfo type summarises the information in an instance declaration
520 instance c => k (t tvs) where b
522 It is used just for *local* instance decls (not ones from interface files).
523 But local instance decls includes
526 as well as explicit user written ones.
531 iSpec :: Instance, -- Includes the dfun id. Its forall'd type
532 iBinds :: InstBindings -- variables scope over the stuff in InstBindings!
535 iDFunId :: InstInfo -> DFunId
536 iDFunId info = instanceDFunId (iSpec info)
539 = VanillaInst -- The normal case
540 (LHsBinds Name) -- Bindings
541 [LSig Name] -- User pragmas recorded for generating
542 -- specialised instances
544 | NewTypeDerived -- Used for deriving instances of newtypes, where the
545 [Type] -- witness dictionary is identical to the argument
546 -- dictionary. Hence no bindings, no pragmas
547 -- The [Type] are the representation types
548 -- See notes in TcDeriv
550 pprInstInfo info = vcat [ptext SLIT("InstInfo:") <+> ppr (idType (iDFunId info))]
552 pprInstInfoDetails info = pprInstInfo info $$ nest 2 (details (iBinds info))
554 details (VanillaInst b _) = pprLHsBinds b
555 details (NewTypeDerived _) = text "Derived from the representation type"
557 simpleInstInfoClsTy :: InstInfo -> (Class, Type)
558 simpleInstInfoClsTy info = case instanceHead (iSpec info) of
559 (_, _, cls, [ty]) -> (cls, ty)
561 simpleInstInfoTy :: InstInfo -> Type
562 simpleInstInfoTy info = snd (simpleInstInfoClsTy info)
564 simpleInstInfoTyCon :: InstInfo -> TyCon
565 -- Gets the type constructor for a simple instance declaration,
566 -- i.e. one of the form instance (...) => C (T a b c) where ...
567 simpleInstInfoTyCon inst = tcTyConAppTyCon (simpleInstInfoTy inst)
571 %************************************************************************
575 %************************************************************************
578 pprBinders :: [Name] -> SDoc
579 -- Used in error messages
580 -- Use quotes for a single one; they look a bit "busy" for several
581 pprBinders [bndr] = quotes (ppr bndr)
582 pprBinders bndrs = pprWithCommas ppr bndrs
585 = failWithTc (ptext SLIT("GHC internal error:") <+> quotes (ppr name) <+>
586 ptext SLIT("is not in scope"))
588 wrongThingErr expected thing name
589 = failWithTc (pprTcTyThingCategory thing <+> quotes (ppr name) <+>
590 ptext SLIT("used as a") <+> text expected)