3 TyThing(..), TcTyThing(..), TcId,
5 -- Instance environment, and InstInfo type
6 InstInfo(..), iDFunId, pprInstInfo, pprInstInfoDetails,
7 simpleInstInfoClsTy, simpleInstInfoTy, simpleInstInfoTyCon,
13 tcLookupLocatedGlobal, tcLookupGlobal,
14 tcLookupField, tcLookupTyCon, tcLookupClass, tcLookupDataCon,
15 tcLookupLocatedGlobalId, tcLookupLocatedTyCon,
19 tcExtendKindEnv, tcExtendKindEnvTvs,
20 tcExtendTyVarEnv, tcExtendTyVarEnv2,
21 tcExtendIdEnv, tcExtendIdEnv1, tcExtendIdEnv2,
22 tcLookup, tcLookupLocated, tcLookupLocalIds, tcLookupLocalId_maybe,
23 tcLookupId, tcLookupTyVar, getScopedTyVarBinds,
24 lclEnvElts, getInLocalScope, findGlobals,
25 wrongThingErr, pprBinders,
28 tcExtendRecEnv, -- For knot-tying
33 -- Global type variables
36 -- Template Haskell stuff
37 checkWellStaged, spliceOK, bracketOK, tcMetaTy, thLevel,
41 newLocalName, newDFunName
44 #include "HsVersions.h"
46 import HsSyn ( LRuleDecl, LHsBinds, LSig,
47 LHsTyVarBndr, HsTyVarBndr(..), pprLHsBinds )
48 import TcIface ( tcImportDecl )
49 import IfaceEnv ( newGlobalBinder )
51 import TcMType ( zonkTcType, zonkTcTyVarsAndFV )
52 import TcType ( Type, TcKind, TcTyVar, TcTyVarSet, TcType, TvSubst,
53 substTy, substTyVar, tyVarsOfType, tcTyVarsOfTypes, mkTyConApp,
54 getDFunTyKey, tcTyConAppTyCon, tcGetTyVar, mkTyVarTy,
55 tidyOpenType, isRefineableTy
57 import qualified Type ( getTyVar_maybe )
58 import Id ( idName, isLocalId, setIdType )
59 import Var ( TyVar, Id, idType, tyVarName )
62 import RdrName ( extendLocalRdrEnv )
63 import InstEnv ( Instance, DFunId, instanceDFunId, instanceHead )
64 import DataCon ( DataCon )
65 import TyCon ( TyCon )
66 import Class ( Class )
67 import Name ( Name, NamedThing(..), getSrcLoc, nameModule )
68 import PrelNames ( thFAKE )
70 import OccName ( mkDFunOcc, occNameString )
71 import HscTypes ( extendTypeEnvList, lookupType, TyThing(..), ExternalPackageState(..) )
72 import SrcLoc ( SrcLoc, Located(..) )
77 %************************************************************************
81 %************************************************************************
83 Using the Located versions (eg. tcLookupLocatedGlobal) is preferred,
84 unless you know that the SrcSpan in the monad is already set to the
88 tcLookupLocatedGlobal :: Located Name -> TcM TyThing
89 -- c.f. IfaceEnvEnv.tcIfaceGlobal
90 tcLookupLocatedGlobal name
91 = addLocM tcLookupGlobal name
93 tcLookupGlobal :: Name -> TcM TyThing
94 -- The Name is almost always an ExternalName, but not always
95 -- In GHCi, we may make command-line bindings (ghci> let x = True)
96 -- that bind a GlobalId, but with an InternalName
98 = do { env <- getGblEnv
101 ; case lookupNameEnv (tcg_type_env env) name of {
102 Just thing -> return thing ;
106 { (eps,hpt) <- getEpsAndHpt
108 ; case lookupType dflags hpt (eps_PTE eps) name of {
109 Just thing -> return thing ;
112 -- Should it have been in the local envt?
113 { let mod = nameModule name
114 ; if mod == tcg_mod env || mod == thFAKE then
115 notFound name -- It should be local, so panic
116 -- The thFAKE possibility is because it
117 -- might be in a declaration bracket
119 tcImportDecl name -- Go find it in an interface
122 tcLookupField :: Name -> TcM Id -- Returns the selector Id
124 = tcLookupGlobal name `thenM` \ thing ->
127 other -> wrongThingErr "field name" (AGlobal thing) name
129 tcLookupDataCon :: Name -> TcM DataCon
131 = tcLookupGlobal name `thenM` \ thing ->
133 ADataCon con -> return con
134 other -> wrongThingErr "data constructor" (AGlobal thing) name
136 tcLookupClass :: Name -> TcM Class
138 = tcLookupGlobal name `thenM` \ thing ->
140 AClass cls -> return cls
141 other -> wrongThingErr "class" (AGlobal thing) name
143 tcLookupTyCon :: Name -> TcM TyCon
145 = tcLookupGlobal name `thenM` \ thing ->
147 ATyCon tc -> return tc
148 other -> wrongThingErr "type constructor" (AGlobal thing) name
150 tcLookupLocatedGlobalId :: Located Name -> TcM Id
151 tcLookupLocatedGlobalId = addLocM tcLookupId
153 tcLookupLocatedClass :: Located Name -> TcM Class
154 tcLookupLocatedClass = addLocM tcLookupClass
156 tcLookupLocatedTyCon :: Located Name -> TcM TyCon
157 tcLookupLocatedTyCon = addLocM tcLookupTyCon
160 %************************************************************************
162 Extending the global environment
164 %************************************************************************
168 tcExtendGlobalEnv :: [TyThing] -> TcM r -> TcM r
169 -- Given a mixture of Ids, TyCons, Classes, all from the
170 -- module being compiled, extend the global environment
171 tcExtendGlobalEnv things thing_inside
172 = do { env <- getGblEnv
173 ; let ge' = extendTypeEnvList (tcg_type_env env) things
174 ; setGblEnv (env {tcg_type_env = ge'}) thing_inside }
176 tcExtendGlobalValEnv :: [Id] -> TcM a -> TcM a
177 -- Same deal as tcExtendGlobalEnv, but for Ids
178 tcExtendGlobalValEnv ids thing_inside
179 = tcExtendGlobalEnv [AnId id | id <- ids] thing_inside
183 tcExtendRecEnv :: [(Name,TyThing)] -> TcM r -> TcM r
184 -- Extend the global environments for the type/class knot tying game
185 tcExtendRecEnv gbl_stuff thing_inside
186 = updGblEnv upd thing_inside
188 upd env = env { tcg_type_env = extend (tcg_type_env env) }
189 extend env = extendNameEnvList env gbl_stuff
193 %************************************************************************
195 \subsection{The local environment}
197 %************************************************************************
200 tcLookupLocated :: Located Name -> TcM TcTyThing
201 tcLookupLocated = addLocM tcLookup
203 tcLookup :: Name -> TcM TcTyThing
205 = getLclEnv `thenM` \ local_env ->
206 case lookupNameEnv (tcl_env local_env) name of
207 Just thing -> returnM thing
208 Nothing -> tcLookupGlobal name `thenM` \ thing ->
209 returnM (AGlobal thing)
211 tcLookupTyVar :: Name -> TcM TcTyVar
213 = tcLookup name `thenM` \ thing ->
215 ATyVar _ ty -> return (tcGetTyVar "tcLookupTyVar" ty)
216 other -> pprPanic "tcLookupTyVar" (ppr name)
218 tcLookupId :: Name -> TcM Id
219 -- Used when we aren't interested in the binding level
220 -- Never a DataCon. (Why does that matter? see TcExpr.tcId)
222 = tcLookup name `thenM` \ thing ->
224 ATcId tc_id _ _ -> returnM tc_id
225 AGlobal (AnId id) -> returnM id
226 other -> pprPanic "tcLookupId" (ppr name)
228 tcLookupLocalId_maybe :: Name -> TcM (Maybe Id)
229 tcLookupLocalId_maybe name
230 = getLclEnv `thenM` \ local_env ->
231 case lookupNameEnv (tcl_env local_env) name of
232 Just (ATcId tc_id _ _) -> return (Just tc_id)
233 other -> return Nothing
235 tcLookupLocalIds :: [Name] -> TcM [TcId]
236 -- We expect the variables to all be bound, and all at
237 -- the same level as the lookup. Only used in one place...
239 = getLclEnv `thenM` \ env ->
240 returnM (map (lookup (tcl_env env) (thLevel (tcl_th_ctxt env))) ns)
243 = case lookupNameEnv lenv name of
244 Just (ATcId id lvl1 _) -> ASSERT( lvl == lvl1 ) id
245 other -> pprPanic "tcLookupLocalIds" (ppr name)
247 lclEnvElts :: TcLclEnv -> [TcTyThing]
248 lclEnvElts env = nameEnvElts (tcl_env env)
250 getInLocalScope :: TcM (Name -> Bool)
252 getInLocalScope = getLclEnv `thenM` \ env ->
254 lcl_env = tcl_env env
256 return (`elemNameEnv` lcl_env)
260 tcExtendKindEnv :: [(Name, TcKind)] -> TcM r -> TcM r
261 tcExtendKindEnv things thing_inside
262 = updLclEnv upd thing_inside
264 upd lcl_env = lcl_env { tcl_env = extend (tcl_env lcl_env) }
265 extend env = extendNameEnvList env [(n, AThing k) | (n,k) <- things]
267 tcExtendKindEnvTvs :: [LHsTyVarBndr Name] -> TcM r -> TcM r
268 tcExtendKindEnvTvs bndrs thing_inside
269 = updLclEnv upd thing_inside
271 upd lcl_env = lcl_env { tcl_env = extend (tcl_env lcl_env) }
272 extend env = extendNameEnvList env pairs
273 pairs = [(n, AThing k) | L _ (KindedTyVar n k) <- bndrs]
275 tcExtendTyVarEnv :: [TyVar] -> TcM r -> TcM r
276 tcExtendTyVarEnv tvs thing_inside
277 = tcExtendTyVarEnv2 [(tyVarName tv, mkTyVarTy tv) | tv <- tvs] thing_inside
279 tcExtendTyVarEnv2 :: [(Name,TcType)] -> TcM r -> TcM r
280 tcExtendTyVarEnv2 binds thing_inside
281 = getLclEnv `thenM` \ env@(TcLclEnv {tcl_env = le,
283 tcl_rdr = rdr_env}) ->
285 rdr_env' = extendLocalRdrEnv rdr_env (map fst binds)
286 new_tv_set = tcTyVarsOfTypes (map snd binds)
287 le' = extendNameEnvList le [(name, ATyVar name ty) | (name, ty) <- binds]
289 -- It's important to add the in-scope tyvars to the global tyvar set
291 -- f (_::r) = let g y = y::r in ...
292 -- Here, g mustn't be generalised. This is also important during
293 -- class and instance decls, when we mustn't generalise the class tyvars
294 -- when typechecking the methods.
295 tc_extend_gtvs gtvs new_tv_set `thenM` \ gtvs' ->
296 setLclEnv (env {tcl_env = le', tcl_tyvars = gtvs', tcl_rdr = rdr_env'}) thing_inside
298 getScopedTyVarBinds :: TcM [(Name, TcType)]
300 = do { lcl_env <- getLclEnv
301 ; return [(name, ty) | ATyVar name ty <- nameEnvElts (tcl_env lcl_env)] }
306 tcExtendIdEnv :: [TcId] -> TcM a -> TcM a
307 -- Invariant: the TcIds are fully zonked. Reasons:
308 -- (a) The kinds of the forall'd type variables are defaulted
309 -- (see Kind.defaultKind, done in zonkQuantifiedTyVar)
310 -- (b) There are no via-Indirect occurrences of the bound variables
311 -- in the types, because instantiation does not look through such things
312 -- (c) The call to tyVarsOfTypes is ok without looking through refs
313 tcExtendIdEnv ids thing_inside = tcExtendIdEnv2 [(idName id, id) | id <- ids] thing_inside
315 tcExtendIdEnv1 :: Name -> TcId -> TcM a -> TcM a
316 tcExtendIdEnv1 name id thing_inside = tcExtendIdEnv2 [(name,id)] thing_inside
318 tcExtendIdEnv2 :: [(Name,TcId)] -> TcM a -> TcM a
319 -- Invariant: the TcIds are fully zonked (see tcExtendIdEnv above)
320 tcExtendIdEnv2 names_w_ids thing_inside
321 = getLclEnv `thenM` \ env ->
323 extra_global_tyvars = tcTyVarsOfTypes [idType id | (_,id) <- names_w_ids]
324 th_lvl = thLevel (tcl_th_ctxt env)
325 extra_env = [ (name, ATcId id th_lvl (isRefineableTy (idType id)))
326 | (name,id) <- names_w_ids]
327 le' = extendNameEnvList (tcl_env env) extra_env
328 rdr_env' = extendLocalRdrEnv (tcl_rdr env) [name | (name,_) <- names_w_ids]
330 traceTc (text "env2") `thenM_`
331 traceTc (text "env3" <+> ppr extra_env) `thenM_`
332 tc_extend_gtvs (tcl_tyvars env) extra_global_tyvars `thenM` \ gtvs' ->
333 (traceTc (text "env4") `thenM_`
334 setLclEnv (env {tcl_env = le', tcl_tyvars = gtvs', tcl_rdr = rdr_env'}) thing_inside)
339 -----------------------
340 -- findGlobals looks at the value environment and finds values
341 -- whose types mention the offending type variable. It has to be
342 -- careful to zonk the Id's type first, so it has to be in the monad.
343 -- We must be careful to pass it a zonked type variable, too.
345 findGlobals :: TcTyVarSet
347 -> TcM (TidyEnv, [SDoc])
349 findGlobals tvs tidy_env
350 = getLclEnv `thenM` \ lcl_env ->
351 go tidy_env [] (lclEnvElts lcl_env)
353 go tidy_env acc [] = returnM (tidy_env, acc)
354 go tidy_env acc (thing : things)
355 = find_thing ignore_it tidy_env thing `thenM` \ (tidy_env1, maybe_doc) ->
357 Just d -> go tidy_env1 (d:acc) things
358 Nothing -> go tidy_env1 acc things
360 ignore_it ty = not (tvs `intersectsVarSet` tyVarsOfType ty)
362 -----------------------
363 find_thing ignore_it tidy_env (ATcId id _ _)
364 = zonkTcType (idType id) `thenM` \ id_ty ->
365 if ignore_it id_ty then
366 returnM (tidy_env, Nothing)
368 (tidy_env', tidy_ty) = tidyOpenType tidy_env id_ty
369 msg = sep [ppr id <+> dcolon <+> ppr tidy_ty,
370 nest 2 (parens (ptext SLIT("bound at") <+>
371 ppr (getSrcLoc id)))]
373 returnM (tidy_env', Just msg)
375 find_thing ignore_it tidy_env (ATyVar tv ty)
376 = zonkTcType ty `thenM` \ tv_ty ->
377 if ignore_it tv_ty then
378 returnM (tidy_env, Nothing)
380 -- The name tv is scoped, so we don't need to tidy it
381 (tidy_env1, tidy_ty) = tidyOpenType tidy_env tv_ty
382 msg = sep [ptext SLIT("Scoped type variable") <+> quotes (ppr tv) <+> eq_stuff, nest 2 bound_at]
384 eq_stuff | Just tv' <- Type.getTyVar_maybe tv_ty,
385 getOccName tv == getOccName tv' = empty
386 | otherwise = equals <+> ppr tidy_ty
387 -- It's ok to use Type.getTyVar_maybe because ty is zonked by now
388 bound_at = parens $ ptext SLIT("bound at:") <+> ppr (getSrcLoc tv)
390 returnM (tidy_env1, Just msg)
392 find_thing _ _ thing = pprPanic "find_thing" (ppr thing)
396 refineEnvironment :: TvSubst -> TcM a -> TcM a
397 refineEnvironment reft thing_inside
398 = do { env <- getLclEnv
399 ; let le' = mapNameEnv refine (tcl_env env)
400 ; gtvs' <- refineGlobalTyVars reft (tcl_tyvars env)
401 ; setLclEnv (env {tcl_env = le', tcl_tyvars = gtvs'}) thing_inside }
403 refine (ATcId id lvl True) = ATcId (setIdType id (substTy reft (idType id))) lvl True
404 refine (ATyVar tv ty) = ATyVar tv (substTy reft ty)
408 %************************************************************************
410 \subsection{The global tyvars}
412 %************************************************************************
415 tc_extend_gtvs gtvs extra_global_tvs
416 = readMutVar gtvs `thenM` \ global_tvs ->
417 newMutVar (global_tvs `unionVarSet` extra_global_tvs)
419 refineGlobalTyVars :: GadtRefinement -> TcRef TcTyVarSet -> TcM (TcRef TcTyVarSet)
420 refineGlobalTyVars reft gtv_var
421 = readMutVar gtv_var `thenM` \ gbl_tvs ->
422 newMutVar (tcTyVarsOfTypes (map (substTyVar reft) (varSetElems gbl_tvs)))
425 @tcGetGlobalTyVars@ returns a fully-zonked set of tyvars free in the environment.
426 To improve subsequent calls to the same function it writes the zonked set back into
430 tcGetGlobalTyVars :: TcM TcTyVarSet
432 = getLclEnv `thenM` \ (TcLclEnv {tcl_tyvars = gtv_var}) ->
433 readMutVar gtv_var `thenM` \ gbl_tvs ->
434 zonkTcTyVarsAndFV (varSetElems gbl_tvs) `thenM` \ gbl_tvs' ->
435 writeMutVar gtv_var gbl_tvs' `thenM_`
440 %************************************************************************
444 %************************************************************************
447 tcExtendRules :: [LRuleDecl Id] -> TcM a -> TcM a
448 -- Just pop the new rules into the EPS and envt resp
449 -- All the rules come from an interface file, not soruce
450 -- Nevertheless, some may be for this module, if we read
451 -- its interface instead of its source code
452 tcExtendRules lcl_rules thing_inside
453 = do { env <- getGblEnv
455 env' = env { tcg_rules = lcl_rules ++ tcg_rules env }
456 ; setGblEnv env' thing_inside }
460 %************************************************************************
464 %************************************************************************
467 instance Outputable ThStage where
468 ppr Comp = text "Comp"
469 ppr (Brack l _ _) = text "Brack" <+> int l
470 ppr (Splice l) = text "Splice" <+> int l
473 thLevel :: ThStage -> ThLevel
474 thLevel Comp = topLevel
475 thLevel (Splice l) = l
476 thLevel (Brack l _ _) = l
479 checkWellStaged :: SDoc -- What the stage check is for
480 -> ThLevel -- Binding level
481 -> ThStage -- Use stage
482 -> TcM () -- Fail if badly staged, adding an error
483 checkWellStaged pp_thing bind_lvl use_stage
484 | bind_lvl <= use_lvl -- OK!
487 | bind_lvl == topLevel -- GHC restriction on top level splices
489 sep [ptext SLIT("GHC stage restriction:") <+> pp_thing,
490 nest 2 (ptext SLIT("is used in a top-level splice, and must be imported, not defined locally"))]
492 | otherwise -- Badly staged
494 ptext SLIT("Stage error:") <+> pp_thing <+>
495 hsep [ptext SLIT("is bound at stage") <+> ppr bind_lvl,
496 ptext SLIT("but used at stage") <+> ppr use_lvl]
498 use_lvl = thLevel use_stage
501 topIdLvl :: Id -> ThLevel
502 -- Globals may either be imported, or may be from an earlier "chunk"
503 -- (separated by declaration splices) of this module. The former
504 -- *can* be used inside a top-level splice, but the latter cannot.
505 -- Hence we give the former impLevel, but the latter topLevel
509 -- By the time we are prcessing the $(f x), the binding for "x"
510 -- will be in the global env, not the local one.
511 topIdLvl id | isLocalId id = topLevel
512 | otherwise = impLevel
514 -- Indicates the legal transitions on bracket( [| |] ).
515 bracketOK :: ThStage -> Maybe ThLevel
516 bracketOK (Brack _ _ _) = Nothing -- Bracket illegal inside a bracket
517 bracketOK stage = Just (thLevel stage + 1)
519 -- Indicates the legal transitions on splice($).
520 spliceOK :: ThStage -> Maybe ThLevel
521 spliceOK (Splice _) = Nothing -- Splice illegal inside splice
522 spliceOK stage = Just (thLevel stage - 1)
524 tcMetaTy :: Name -> TcM Type
525 -- Given the name of a Template Haskell data type,
527 -- E.g. given the name "Expr" return the type "Expr"
529 = tcLookupTyCon tc_name `thenM` \ t ->
530 returnM (mkTyConApp t [])
534 %************************************************************************
536 \subsection{The InstInfo type}
538 %************************************************************************
540 The InstInfo type summarises the information in an instance declaration
542 instance c => k (t tvs) where b
544 It is used just for *local* instance decls (not ones from interface files).
545 But local instance decls includes
548 as well as explicit user written ones.
553 iSpec :: Instance, -- Includes the dfun id. Its forall'd type
554 iBinds :: InstBindings -- variables scope over the stuff in InstBindings!
557 iDFunId :: InstInfo -> DFunId
558 iDFunId info = instanceDFunId (iSpec info)
561 = VanillaInst -- The normal case
562 (LHsBinds Name) -- Bindings
563 [LSig Name] -- User pragmas recorded for generating
564 -- specialised instances
566 | NewTypeDerived -- Used for deriving instances of newtypes, where the
567 [Type] -- witness dictionary is identical to the argument
568 -- dictionary. Hence no bindings, no pragmas
569 -- The [Type] are the representation types
570 -- See notes in TcDeriv
572 pprInstInfo info = vcat [ptext SLIT("InstInfo:") <+> ppr (idType (iDFunId info))]
574 pprInstInfoDetails info = pprInstInfo info $$ nest 2 (details (iBinds info))
576 details (VanillaInst b _) = pprLHsBinds b
577 details (NewTypeDerived _) = text "Derived from the representation type"
579 simpleInstInfoClsTy :: InstInfo -> (Class, Type)
580 simpleInstInfoClsTy info = case instanceHead (iSpec info) of
581 (_, _, cls, [ty]) -> (cls, ty)
583 simpleInstInfoTy :: InstInfo -> Type
584 simpleInstInfoTy info = snd (simpleInstInfoClsTy info)
586 simpleInstInfoTyCon :: InstInfo -> TyCon
587 -- Gets the type constructor for a simple instance declaration,
588 -- i.e. one of the form instance (...) => C (T a b c) where ...
589 simpleInstInfoTyCon inst = tcTyConAppTyCon (simpleInstInfoTy inst)
592 Make a name for the dict fun for an instance decl. It's an *external*
593 name, like otber top-level names, and hence must be made with newGlobalBinder.
596 newDFunName :: Class -> [Type] -> SrcLoc -> TcM Name
597 newDFunName clas (ty:_) loc
598 = do { index <- nextDFunIndex
599 ; is_boot <- tcIsHsBoot
601 ; let info_string = occNameString (getOccName clas) ++
602 occNameString (getDFunTyKey ty)
603 dfun_occ = mkDFunOcc info_string is_boot index
605 ; newGlobalBinder mod dfun_occ Nothing loc }
607 newDFunName clas [] loc = pprPanic "newDFunName" (ppr clas <+> ppr loc)
611 %************************************************************************
615 %************************************************************************
618 pprBinders :: [Name] -> SDoc
619 -- Used in error messages
620 -- Use quotes for a single one; they look a bit "busy" for several
621 pprBinders [bndr] = quotes (ppr bndr)
622 pprBinders bndrs = pprWithCommas ppr bndrs
625 = failWithTc (ptext SLIT("GHC internal error:") <+> quotes (ppr name) <+>
626 ptext SLIT("is not in scope"))
628 wrongThingErr expected thing name
629 = failWithTc (pprTcTyThingCategory thing <+> quotes (ppr name) <+>
630 ptext SLIT("used as a") <+> text expected)