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,
19 tcExtendKindEnv, tcExtendKindEnvTvs,
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,
46 LHsTyVarBndr, HsTyVarBndr(..), pprLHsBinds )
47 import TcIface ( tcImportDecl )
48 import IfaceEnv ( newGlobalBinder )
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, nameModule, isExternalName )
67 import PrelNames ( thFAKE )
69 import OccName ( mkDFunOcc, occNameString )
70 import HscTypes ( extendTypeEnvList, lookupType,
71 TyThing(..), tyThingId, tyThingDataCon,
72 ExternalPackageState(..) )
74 import SrcLoc ( SrcLoc, Located(..) )
79 %************************************************************************
83 %************************************************************************
85 Using the Located versions (eg. tcLookupLocatedGlobal) is preferred,
86 unless you know that the SrcSpan in the monad is already set to the
90 tcLookupLocatedGlobal :: Located Name -> TcM TyThing
91 -- c.f. IfaceEnvEnv.tcIfaceGlobal
92 tcLookupLocatedGlobal name
93 = addLocM tcLookupGlobal name
95 tcLookupGlobal :: Name -> TcM TyThing
96 -- The Name is almost always an ExternalName, but not always
97 -- In GHCi, we may make command-line bindings (ghci> let x = True)
98 -- that bind a GlobalId, but with an InternalName
100 = do { env <- getGblEnv
103 ; case lookupNameEnv (tcg_type_env env) name of {
104 Just thing -> return thing ;
108 { (eps,hpt) <- getEpsAndHpt
109 ; case lookupType hpt (eps_PTE eps) name of {
110 Just thing -> return thing ;
113 -- Should it have been in the local envt?
114 { let mod = nameModule name
115 ; if mod == tcg_mod env || mod == thFAKE then
116 notFound name -- It should be local, so panic
117 -- The thFAKE possibility is because it
118 -- might be in a declaration bracket
120 tcImportDecl name -- Go find it in an interface
123 tcLookupGlobalId :: Name -> TcM Id
124 -- Never used for Haskell-source DataCons, hence no ADataCon case
125 tcLookupGlobalId name
126 = tcLookupGlobal name `thenM` \ thing ->
127 return (tyThingId thing)
129 tcLookupDataCon :: Name -> TcM DataCon
130 tcLookupDataCon con_name
131 = tcLookupGlobal con_name `thenM` \ thing ->
132 return (tyThingDataCon thing)
134 tcLookupClass :: Name -> TcM Class
136 = tcLookupGlobal name `thenM` \ thing ->
138 AClass cls -> return cls
139 other -> wrongThingErr "class" (AGlobal thing) name
141 tcLookupTyCon :: Name -> TcM TyCon
143 = tcLookupGlobal name `thenM` \ thing ->
145 ATyCon tc -> return tc
146 other -> wrongThingErr "type constructor" (AGlobal thing) name
148 tcLookupLocatedGlobalId :: Located Name -> TcM Id
149 tcLookupLocatedGlobalId = addLocM tcLookupId
151 tcLookupLocatedClass :: Located Name -> TcM Class
152 tcLookupLocatedClass = addLocM tcLookupClass
154 tcLookupLocatedTyCon :: Located Name -> TcM TyCon
155 tcLookupLocatedTyCon = addLocM tcLookupTyCon
158 %************************************************************************
160 Extending the global environment
162 %************************************************************************
166 tcExtendGlobalEnv :: [TyThing] -> TcM r -> TcM r
167 -- Given a mixture of Ids, TyCons, Classes, all from the
168 -- module being compiled, extend the global environment
169 tcExtendGlobalEnv things thing_inside
170 = do { env <- getGblEnv
171 ; let ge' = extendTypeEnvList (tcg_type_env env) things
172 ; setGblEnv (env {tcg_type_env = ge'}) thing_inside }
174 tcExtendGlobalValEnv :: [Id] -> TcM a -> TcM a
175 -- Same deal as tcExtendGlobalEnv, but for Ids
176 tcExtendGlobalValEnv ids thing_inside
177 = tcExtendGlobalEnv [AnId id | id <- ids] thing_inside
181 tcExtendRecEnv :: [(Name,TyThing)] -> TcM r -> TcM r
182 -- Extend the global environments for the type/class knot tying game
183 tcExtendRecEnv gbl_stuff thing_inside
184 = updGblEnv upd thing_inside
186 upd env = env { tcg_type_env = extend (tcg_type_env env) }
187 extend env = extendNameEnvList env gbl_stuff
191 %************************************************************************
193 \subsection{The local environment}
195 %************************************************************************
198 tcLookupLocated :: Located Name -> TcM TcTyThing
199 tcLookupLocated = addLocM tcLookup
201 tcLookup :: Name -> TcM TcTyThing
203 = getLclEnv `thenM` \ local_env ->
204 case lookupNameEnv (tcl_env local_env) name of
205 Just thing -> returnM thing
206 Nothing -> tcLookupGlobal name `thenM` \ thing ->
207 returnM (AGlobal thing)
209 tcLookupTyVar :: Name -> TcM TcTyVar
211 = tcLookup name `thenM` \ thing ->
213 ATyVar _ ty -> returnM (tcGetTyVar "tcLookupTyVar" ty)
214 other -> pprPanic "tcLookupTyVar" (ppr name)
216 tcLookupId :: Name -> TcM Id
217 -- Used when we aren't interested in the binding level
218 -- Never a DataCon. (Why does that matter? see TcExpr.tcId)
220 = tcLookup name `thenM` \ thing ->
222 ATcId tc_id _ -> returnM tc_id
223 AGlobal (AnId id) -> returnM id
224 other -> pprPanic "tcLookupId" (ppr name)
226 tcLookupLocalIds :: [Name] -> TcM [TcId]
227 -- We expect the variables to all be bound, and all at
228 -- the same level as the lookup. Only used in one place...
230 = getLclEnv `thenM` \ env ->
231 returnM (map (lookup (tcl_env env) (thLevel (tcl_th_ctxt env))) ns)
234 = case lookupNameEnv lenv name of
235 Just (ATcId id lvl1) -> ASSERT( lvl == lvl1 ) id
236 other -> pprPanic "tcLookupLocalIds" (ppr name)
238 lclEnvElts :: TcLclEnv -> [TcTyThing]
239 lclEnvElts env = nameEnvElts (tcl_env env)
241 getInLocalScope :: TcM (Name -> Bool)
243 getInLocalScope = getLclEnv `thenM` \ env ->
245 lcl_env = tcl_env env
247 return (`elemNameEnv` lcl_env)
251 tcExtendKindEnv :: [(Name, TcKind)] -> TcM r -> TcM r
252 tcExtendKindEnv things thing_inside
253 = updLclEnv upd thing_inside
255 upd lcl_env = lcl_env { tcl_env = extend (tcl_env lcl_env) }
256 extend env = extendNameEnvList env [(n, AThing k) | (n,k) <- things]
258 tcExtendKindEnvTvs :: [LHsTyVarBndr Name] -> TcM r -> TcM r
259 tcExtendKindEnvTvs bndrs thing_inside
260 = updLclEnv upd thing_inside
262 upd lcl_env = lcl_env { tcl_env = extend (tcl_env lcl_env) }
263 extend env = extendNameEnvList env pairs
264 pairs = [(n, AThing k) | L _ (KindedTyVar n k) <- bndrs]
266 tcExtendTyVarEnv :: [TyVar] -> TcM r -> TcM r
267 tcExtendTyVarEnv tvs thing_inside
268 = tcExtendTyVarEnv2 [(tyVarName tv, mkTyVarTy tv) | tv <- tvs] thing_inside
270 tcExtendTyVarEnv2 :: [(Name,TcType)] -> TcM r -> TcM r
271 tcExtendTyVarEnv2 binds thing_inside
272 = getLclEnv `thenM` \ env@(TcLclEnv {tcl_env = le,
274 tcl_rdr = rdr_env}) ->
276 rdr_env' = extendLocalRdrEnv rdr_env (map fst binds)
277 new_tv_set = tyVarsOfTypes (map snd binds)
278 le' = extendNameEnvList le [(name, ATyVar name ty) | (name, ty) <- binds]
280 -- It's important to add the in-scope tyvars to the global tyvar set
282 -- f (_::r) = let g y = y::r in ...
283 -- Here, g mustn't be generalised. This is also important during
284 -- class and instance decls, when we mustn't generalise the class tyvars
285 -- when typechecking the methods.
286 tc_extend_gtvs gtvs new_tv_set `thenM` \ gtvs' ->
287 setLclEnv (env {tcl_env = le', tcl_tyvars = gtvs', tcl_rdr = rdr_env'}) thing_inside
292 tcExtendIdEnv :: [TcId] -> TcM a -> TcM a
293 -- Invariant: the TcIds are fully zonked. Reasons:
294 -- (a) The kinds of the forall'd type variables are defaulted
295 -- (see Kind.defaultKind, done in zonkQuantifiedTyVar)
296 -- (b) There are no via-Indirect occurrences of the bound variables
297 -- in the types, because instantiation does not look through such things
298 -- (c) The call to tyVarsOfTypes is ok without looking through refs
299 tcExtendIdEnv ids thing_inside = tcExtendIdEnv2 [(idName id, id) | id <- ids] thing_inside
301 tcExtendIdEnv1 :: Name -> TcId -> TcM a -> TcM a
302 tcExtendIdEnv1 name id thing_inside = tcExtendIdEnv2 [(name,id)] thing_inside
304 tcExtendIdEnv2 :: [(Name,TcId)] -> TcM a -> TcM a
305 -- Invariant: the TcIds are fully zonked (see tcExtendIdEnv above)
306 tcExtendIdEnv2 names_w_ids thing_inside
307 = getLclEnv `thenM` \ env ->
309 extra_global_tyvars = tyVarsOfTypes [idType id | (name,id) <- names_w_ids]
310 th_lvl = thLevel (tcl_th_ctxt env)
311 extra_env = [(name, ATcId id th_lvl) | (name,id) <- names_w_ids]
312 le' = extendNameEnvList (tcl_env env) extra_env
313 rdr_env' = extendLocalRdrEnv (tcl_rdr env) (map fst names_w_ids)
315 tc_extend_gtvs (tcl_tyvars env) extra_global_tyvars `thenM` \ gtvs' ->
316 setLclEnv (env {tcl_env = le', tcl_tyvars = gtvs', tcl_rdr = rdr_env'}) thing_inside
321 -----------------------
322 -- findGlobals looks at the value environment and finds values
323 -- whose types mention the offending type variable. It has to be
324 -- careful to zonk the Id's type first, so it has to be in the monad.
325 -- We must be careful to pass it a zonked type variable, too.
327 findGlobals :: TcTyVarSet
329 -> TcM (TidyEnv, [SDoc])
331 findGlobals tvs tidy_env
332 = getLclEnv `thenM` \ lcl_env ->
333 go tidy_env [] (lclEnvElts lcl_env)
335 go tidy_env acc [] = returnM (tidy_env, acc)
336 go tidy_env acc (thing : things)
337 = find_thing ignore_it tidy_env thing `thenM` \ (tidy_env1, maybe_doc) ->
339 Just d -> go tidy_env1 (d:acc) things
340 Nothing -> go tidy_env1 acc things
342 ignore_it ty = not (tvs `intersectsVarSet` tyVarsOfType ty)
344 -----------------------
345 find_thing ignore_it tidy_env (ATcId id _)
346 = zonkTcType (idType id) `thenM` \ id_ty ->
347 if ignore_it id_ty then
348 returnM (tidy_env, Nothing)
350 (tidy_env', tidy_ty) = tidyOpenType tidy_env id_ty
351 msg = sep [ppr id <+> dcolon <+> ppr tidy_ty,
352 nest 2 (parens (ptext SLIT("bound at") <+>
353 ppr (getSrcLoc id)))]
355 returnM (tidy_env', Just msg)
357 find_thing ignore_it tidy_env (ATyVar tv ty)
358 = zonkTcType ty `thenM` \ tv_ty ->
359 if ignore_it tv_ty then
360 returnM (tidy_env, Nothing)
362 -- The name tv is scoped, so we don't need to tidy it
363 (tidy_env1, tidy_ty) = tidyOpenType tidy_env tv_ty
364 msg = sep [ptext SLIT("Scoped type variable") <+> quotes (ppr tv) <+> eq_stuff, nest 2 bound_at]
366 eq_stuff | Just tv' <- Type.getTyVar_maybe tv_ty,
367 getOccName tv == getOccName tv' = empty
368 | otherwise = equals <+> ppr tidy_ty
369 -- It's ok to use Type.getTyVar_maybe because ty is zonked by now
370 bound_at = parens $ ptext SLIT("bound at:") <+> ppr (getSrcLoc tv)
372 returnM (tidy_env1, Just msg)
376 %************************************************************************
378 \subsection{The global tyvars}
380 %************************************************************************
383 tc_extend_gtvs gtvs extra_global_tvs
384 = readMutVar gtvs `thenM` \ global_tvs ->
385 newMutVar (global_tvs `unionVarSet` extra_global_tvs)
388 @tcGetGlobalTyVars@ returns a fully-zonked set of tyvars free in the environment.
389 To improve subsequent calls to the same function it writes the zonked set back into
393 tcGetGlobalTyVars :: TcM TcTyVarSet
395 = getLclEnv `thenM` \ (TcLclEnv {tcl_tyvars = gtv_var}) ->
396 readMutVar gtv_var `thenM` \ gbl_tvs ->
397 zonkTcTyVarsAndFV (varSetElems gbl_tvs) `thenM` \ gbl_tvs' ->
398 writeMutVar gtv_var gbl_tvs' `thenM_`
403 %************************************************************************
407 %************************************************************************
410 tcExtendRules :: [LRuleDecl Id] -> TcM a -> TcM a
411 -- Just pop the new rules into the EPS and envt resp
412 -- All the rules come from an interface file, not soruce
413 -- Nevertheless, some may be for this module, if we read
414 -- its interface instead of its source code
415 tcExtendRules lcl_rules thing_inside
416 = do { env <- getGblEnv
418 env' = env { tcg_rules = lcl_rules ++ tcg_rules env }
419 ; setGblEnv env' thing_inside }
423 %************************************************************************
427 %************************************************************************
430 instance Outputable ThStage where
431 ppr Comp = text "Comp"
432 ppr (Brack l _ _) = text "Brack" <+> int l
433 ppr (Splice l) = text "Splice" <+> int l
436 thLevel :: ThStage -> ThLevel
437 thLevel Comp = topLevel
438 thLevel (Splice l) = l
439 thLevel (Brack l _ _) = l
442 checkWellStaged :: SDoc -- What the stage check is for
443 -> ThLevel -- Binding level
444 -> ThStage -- Use stage
445 -> TcM () -- Fail if badly staged, adding an error
446 checkWellStaged pp_thing bind_lvl use_stage
447 | bind_lvl <= use_lvl -- OK!
450 | bind_lvl == topLevel -- GHC restriction on top level splices
452 sep [ptext SLIT("GHC stage restriction:") <+> pp_thing,
453 nest 2 (ptext SLIT("is used in a top-level splice, and must be imported, not defined locally"))]
455 | otherwise -- Badly staged
457 ptext SLIT("Stage error:") <+> pp_thing <+>
458 hsep [ptext SLIT("is bound at stage") <+> ppr bind_lvl,
459 ptext SLIT("but used at stage") <+> ppr use_lvl]
461 use_lvl = thLevel use_stage
464 topIdLvl :: Id -> ThLevel
465 -- Globals may either be imported, or may be from an earlier "chunk"
466 -- (separated by declaration splices) of this module. The former
467 -- *can* be used inside a top-level splice, but the latter cannot.
468 -- Hence we give the former impLevel, but the latter topLevel
472 -- By the time we are prcessing the $(f x), the binding for "x"
473 -- will be in the global env, not the local one.
474 topIdLvl id | isLocalId id = topLevel
475 | otherwise = impLevel
477 -- Indicates the legal transitions on bracket( [| |] ).
478 bracketOK :: ThStage -> Maybe ThLevel
479 bracketOK (Brack _ _ _) = Nothing -- Bracket illegal inside a bracket
480 bracketOK stage = Just (thLevel stage + 1)
482 -- Indicates the legal transitions on splice($).
483 spliceOK :: ThStage -> Maybe ThLevel
484 spliceOK (Splice _) = Nothing -- Splice illegal inside splice
485 spliceOK stage = Just (thLevel stage - 1)
487 tcMetaTy :: Name -> TcM Type
488 -- Given the name of a Template Haskell data type,
490 -- E.g. given the name "Expr" return the type "Expr"
492 = tcLookupTyCon tc_name `thenM` \ t ->
493 returnM (mkGenTyConApp t [])
494 -- Use mkGenTyConApp because it might be a synonym
498 %************************************************************************
500 \subsection{The InstInfo type}
502 %************************************************************************
504 The InstInfo type summarises the information in an instance declaration
506 instance c => k (t tvs) where b
508 It is used just for *local* instance decls (not ones from interface files).
509 But local instance decls includes
512 as well as explicit user written ones.
517 iSpec :: Instance, -- Includes the dfun id. Its forall'd type
518 iBinds :: InstBindings -- variables scope over the stuff in InstBindings!
521 iDFunId :: InstInfo -> DFunId
522 iDFunId info = instanceDFunId (iSpec info)
525 = VanillaInst -- The normal case
526 (LHsBinds Name) -- Bindings
527 [LSig Name] -- User pragmas recorded for generating
528 -- specialised instances
530 | NewTypeDerived -- Used for deriving instances of newtypes, where the
531 [Type] -- witness dictionary is identical to the argument
532 -- dictionary. Hence no bindings, no pragmas
533 -- The [Type] are the representation types
534 -- See notes in TcDeriv
536 pprInstInfo info = vcat [ptext SLIT("InstInfo:") <+> ppr (idType (iDFunId info))]
538 pprInstInfoDetails info = pprInstInfo info $$ nest 2 (details (iBinds info))
540 details (VanillaInst b _) = pprLHsBinds b
541 details (NewTypeDerived _) = text "Derived from the representation type"
543 simpleInstInfoClsTy :: InstInfo -> (Class, Type)
544 simpleInstInfoClsTy info = case instanceHead (iSpec info) of
545 (_, _, cls, [ty]) -> (cls, ty)
547 simpleInstInfoTy :: InstInfo -> Type
548 simpleInstInfoTy info = snd (simpleInstInfoClsTy info)
550 simpleInstInfoTyCon :: InstInfo -> TyCon
551 -- Gets the type constructor for a simple instance declaration,
552 -- i.e. one of the form instance (...) => C (T a b c) where ...
553 simpleInstInfoTyCon inst = tcTyConAppTyCon (simpleInstInfoTy inst)
556 Make a name for the dict fun for an instance decl. It's an *external*
557 name, like otber top-level names, and hence must be made with newGlobalBinder.
560 newDFunName :: Class -> [Type] -> SrcLoc -> TcM Name
561 newDFunName clas (ty:_) loc
562 = do { index <- nextDFunIndex
563 ; is_boot <- tcIsHsBoot
565 ; let info_string = occNameString (getOccName clas) ++
566 occNameString (getDFunTyKey ty)
567 dfun_occ = mkDFunOcc info_string is_boot index
569 ; newGlobalBinder mod dfun_occ Nothing loc }
571 newDFunName clas [] loc = pprPanic "newDFunName" (ppr clas <+> ppr loc)
575 %************************************************************************
579 %************************************************************************
582 pprBinders :: [Name] -> SDoc
583 -- Used in error messages
584 -- Use quotes for a single one; they look a bit "busy" for several
585 pprBinders [bndr] = quotes (ppr bndr)
586 pprBinders bndrs = pprWithCommas ppr bndrs
589 = failWithTc (ptext SLIT("GHC internal error:") <+> quotes (ppr name) <+>
590 ptext SLIT("is not in scope"))
592 wrongThingErr expected thing name
593 = failWithTc (pprTcTyThingCategory thing <+> quotes (ppr name) <+>
594 ptext SLIT("used as a") <+> text expected)