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,
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, newFamInstTyConName
44 #include "HsVersions.h"
46 import HsSyn ( LRuleDecl, LHsBinds, LSig,
47 LHsTyVarBndr, HsTyVarBndr(..), pprLHsBinds,
49 import TcIface ( tcImportDecl )
50 import IfaceEnv ( newGlobalBinder )
52 import TcMType ( zonkTcType, zonkTcTyVarsAndFV )
53 import TcType ( Type, TcKind, TcTyVar, TcTyVarSet, TcType,
54 substTy, tyVarsOfType, tcTyVarsOfTypes, mkTyConApp,
55 getDFunTyKey, tcTyConAppTyCon, tcGetTyVar, mkTyVarTy,
56 tidyOpenType, isRefineableTy
58 import TcGadt ( Refinement, refineType )
59 import qualified Type ( getTyVar_maybe )
60 import Id ( idName, isLocalId )
61 import Var ( TyVar, Id, idType, tyVarName )
64 import RdrName ( extendLocalRdrEnv )
65 import InstEnv ( Instance, DFunId, instanceDFunId, instanceHead )
66 import DataCon ( DataCon )
67 import TyCon ( TyCon )
68 import Class ( Class )
69 import Name ( Name, NamedThing(..), getSrcLoc, nameModule,
71 import PrelNames ( thFAKE )
73 import OccName ( mkDFunOcc, occNameString, mkInstTyTcOcc )
74 import HscTypes ( extendTypeEnvList, lookupType, TyThing(..),
75 ExternalPackageState(..) )
76 import SrcLoc ( SrcLoc, Located(..) )
81 %************************************************************************
85 %************************************************************************
87 Using the Located versions (eg. tcLookupLocatedGlobal) is preferred,
88 unless you know that the SrcSpan in the monad is already set to the
92 tcLookupLocatedGlobal :: Located Name -> TcM TyThing
93 -- c.f. IfaceEnvEnv.tcIfaceGlobal
94 tcLookupLocatedGlobal name
95 = addLocM tcLookupGlobal name
97 tcLookupGlobal :: Name -> TcM TyThing
98 -- The Name is almost always an ExternalName, but not always
99 -- In GHCi, we may make command-line bindings (ghci> let x = True)
100 -- that bind a GlobalId, but with an InternalName
102 = do { env <- getGblEnv
105 ; case lookupNameEnv (tcg_type_env env) name of {
106 Just thing -> return thing ;
110 { (eps,hpt) <- getEpsAndHpt
112 ; case lookupType dflags hpt (eps_PTE eps) name of {
113 Just thing -> return thing ;
116 -- Should it have been in the local envt?
117 { let mod = nameModule name
118 ; if mod == tcg_mod env || mod == thFAKE then
119 notFound name -- It should be local, so panic
120 -- The thFAKE possibility is because it
121 -- might be in a declaration bracket
123 tcImportDecl name -- Go find it in an interface
126 tcLookupField :: Name -> TcM Id -- Returns the selector Id
128 = tcLookupGlobal name `thenM` \ thing ->
131 other -> wrongThingErr "field name" (AGlobal thing) name
133 tcLookupDataCon :: Name -> TcM DataCon
135 = tcLookupGlobal name `thenM` \ thing ->
137 ADataCon con -> return con
138 other -> wrongThingErr "data constructor" (AGlobal thing) name
140 tcLookupClass :: Name -> TcM Class
142 = tcLookupGlobal name `thenM` \ thing ->
144 AClass cls -> return cls
145 other -> wrongThingErr "class" (AGlobal thing) name
147 tcLookupTyCon :: Name -> TcM TyCon
149 = tcLookupGlobal name `thenM` \ thing ->
151 ATyCon tc -> return tc
152 other -> wrongThingErr "type constructor" (AGlobal thing) name
154 tcLookupLocatedGlobalId :: Located Name -> TcM Id
155 tcLookupLocatedGlobalId = addLocM tcLookupId
157 tcLookupLocatedClass :: Located Name -> TcM Class
158 tcLookupLocatedClass = addLocM tcLookupClass
160 tcLookupLocatedTyCon :: Located Name -> TcM TyCon
161 tcLookupLocatedTyCon = addLocM tcLookupTyCon
164 %************************************************************************
166 Extending the global environment
168 %************************************************************************
172 tcExtendGlobalEnv :: [TyThing] -> TcM r -> TcM r
173 -- Given a mixture of Ids, TyCons, Classes, all from the
174 -- module being compiled, extend the global environment
175 tcExtendGlobalEnv things thing_inside
176 = do { env <- getGblEnv
177 ; let ge' = extendTypeEnvList (tcg_type_env env) things
178 ; setGblEnv (env {tcg_type_env = ge'}) thing_inside }
180 tcExtendGlobalValEnv :: [Id] -> TcM a -> TcM a
181 -- Same deal as tcExtendGlobalEnv, but for Ids
182 tcExtendGlobalValEnv ids thing_inside
183 = tcExtendGlobalEnv [AnId id | id <- ids] thing_inside
187 tcExtendRecEnv :: [(Name,TyThing)] -> TcM r -> TcM r
188 -- Extend the global environments for the type/class knot tying game
189 tcExtendRecEnv gbl_stuff thing_inside
190 = updGblEnv upd thing_inside
192 upd env = env { tcg_type_env = extend (tcg_type_env env) }
193 extend env = extendNameEnvList env gbl_stuff
197 %************************************************************************
199 \subsection{The local environment}
201 %************************************************************************
204 tcLookupLocated :: Located Name -> TcM TcTyThing
205 tcLookupLocated = addLocM tcLookup
207 tcLookup :: Name -> TcM TcTyThing
209 = getLclEnv `thenM` \ local_env ->
210 case lookupNameEnv (tcl_env local_env) name of
211 Just thing -> returnM thing
212 Nothing -> tcLookupGlobal name `thenM` \ thing ->
213 returnM (AGlobal thing)
215 tcLookupTyVar :: Name -> TcM TcTyVar
217 = tcLookup name `thenM` \ thing ->
219 ATyVar _ ty -> return (tcGetTyVar "tcLookupTyVar" ty)
220 other -> pprPanic "tcLookupTyVar" (ppr name)
222 tcLookupId :: Name -> TcM Id
223 -- Used when we aren't interested in the binding level, nor refinement.
224 -- The "no refinement" part means that we return the un-refined Id regardless
226 -- The Id is never a DataCon. (Why does that matter? see TcExpr.tcId)
228 = tcLookup name `thenM` \ thing ->
230 ATcId { tct_id = id} -> returnM id
231 AGlobal (AnId id) -> returnM id
232 other -> pprPanic "tcLookupId" (ppr name)
234 tcLookupLocalIds :: [Name] -> TcM [TcId]
235 -- We expect the variables to all be bound, and all at
236 -- the same level as the lookup. Only used in one place...
238 = getLclEnv `thenM` \ env ->
239 returnM (map (lookup (tcl_env env) (thLevel (tcl_th_ctxt env))) ns)
242 = case lookupNameEnv lenv name of
243 Just (ATcId { tct_id = id, tct_level = lvl1 })
244 -> 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 { tct_id = id,
328 tct_co = if isRefineableTy id_ty
331 | (name,id) <- names_w_ids, let id_ty = idType id]
332 le' = extendNameEnvList (tcl_env env) extra_env
333 rdr_env' = extendLocalRdrEnv (tcl_rdr env) [name | (name,_) <- names_w_ids]
335 traceTc (text "env2") `thenM_`
336 traceTc (text "env3" <+> ppr extra_env) `thenM_`
337 tc_extend_gtvs (tcl_tyvars env) extra_global_tyvars `thenM` \ gtvs' ->
338 (traceTc (text "env4") `thenM_`
339 setLclEnv (env {tcl_env = le', tcl_tyvars = gtvs', tcl_rdr = rdr_env'}) thing_inside)
344 -----------------------
345 -- findGlobals looks at the value environment and finds values
346 -- whose types mention the offending type variable. It has to be
347 -- careful to zonk the Id's type first, so it has to be in the monad.
348 -- We must be careful to pass it a zonked type variable, too.
350 findGlobals :: TcTyVarSet
352 -> TcM (TidyEnv, [SDoc])
354 findGlobals tvs tidy_env
355 = getLclEnv `thenM` \ lcl_env ->
356 go tidy_env [] (lclEnvElts lcl_env)
358 go tidy_env acc [] = returnM (tidy_env, acc)
359 go tidy_env acc (thing : things)
360 = find_thing ignore_it tidy_env thing `thenM` \ (tidy_env1, maybe_doc) ->
362 Just d -> go tidy_env1 (d:acc) things
363 Nothing -> go tidy_env1 acc things
365 ignore_it ty = not (tvs `intersectsVarSet` tyVarsOfType ty)
367 -----------------------
368 find_thing ignore_it tidy_env (ATcId { tct_id = id })
369 = zonkTcType (idType id) `thenM` \ id_ty ->
370 if ignore_it id_ty then
371 returnM (tidy_env, Nothing)
373 (tidy_env', tidy_ty) = tidyOpenType tidy_env id_ty
374 msg = sep [ppr id <+> dcolon <+> ppr tidy_ty,
375 nest 2 (parens (ptext SLIT("bound at") <+>
376 ppr (getSrcLoc id)))]
378 returnM (tidy_env', Just msg)
380 find_thing ignore_it tidy_env (ATyVar tv ty)
381 = zonkTcType ty `thenM` \ tv_ty ->
382 if ignore_it tv_ty then
383 returnM (tidy_env, Nothing)
385 -- The name tv is scoped, so we don't need to tidy it
386 (tidy_env1, tidy_ty) = tidyOpenType tidy_env tv_ty
387 msg = sep [ptext SLIT("Scoped type variable") <+> quotes (ppr tv) <+> eq_stuff, nest 2 bound_at]
389 eq_stuff | Just tv' <- Type.getTyVar_maybe tv_ty,
390 getOccName tv == getOccName tv' = empty
391 | otherwise = equals <+> ppr tidy_ty
392 -- It's ok to use Type.getTyVar_maybe because ty is zonked by now
393 bound_at = parens $ ptext SLIT("bound at:") <+> ppr (getSrcLoc tv)
395 returnM (tidy_env1, Just msg)
397 find_thing _ _ thing = pprPanic "find_thing" (ppr thing)
401 refineEnvironment :: Refinement -> TcM a -> TcM a
402 -- I don't think I have to refine the set of global type variables in scope
403 -- Reason: the refinement never increases that set
404 refineEnvironment reft thing_inside
405 = do { env <- getLclEnv
406 ; let le' = mapNameEnv refine (tcl_env env)
407 ; setLclEnv (env {tcl_env = le'}) thing_inside }
409 refine elt@(ATcId { tct_co = Just co, tct_type = ty })
410 = let (co', ty') = refineType reft ty
411 in elt { tct_co = Just (co' <.> co), tct_type = ty' }
412 refine (ATyVar tv ty) = ATyVar tv (snd (refineType reft ty))
413 -- Ignore the coercion that refineType returns
417 %************************************************************************
419 \subsection{The global tyvars}
421 %************************************************************************
424 tc_extend_gtvs gtvs extra_global_tvs
425 = readMutVar gtvs `thenM` \ global_tvs ->
426 newMutVar (global_tvs `unionVarSet` extra_global_tvs)
429 @tcGetGlobalTyVars@ returns a fully-zonked set of tyvars free in the environment.
430 To improve subsequent calls to the same function it writes the zonked set back into
434 tcGetGlobalTyVars :: TcM TcTyVarSet
436 = getLclEnv `thenM` \ (TcLclEnv {tcl_tyvars = gtv_var}) ->
437 readMutVar gtv_var `thenM` \ gbl_tvs ->
438 zonkTcTyVarsAndFV (varSetElems gbl_tvs) `thenM` \ gbl_tvs' ->
439 writeMutVar gtv_var gbl_tvs' `thenM_`
444 %************************************************************************
448 %************************************************************************
451 tcExtendRules :: [LRuleDecl Id] -> TcM a -> TcM a
452 -- Just pop the new rules into the EPS and envt resp
453 -- All the rules come from an interface file, not soruce
454 -- Nevertheless, some may be for this module, if we read
455 -- its interface instead of its source code
456 tcExtendRules lcl_rules thing_inside
457 = do { env <- getGblEnv
459 env' = env { tcg_rules = lcl_rules ++ tcg_rules env }
460 ; setGblEnv env' thing_inside }
464 %************************************************************************
468 %************************************************************************
471 instance Outputable ThStage where
472 ppr Comp = text "Comp"
473 ppr (Brack l _ _) = text "Brack" <+> int l
474 ppr (Splice l) = text "Splice" <+> int l
477 thLevel :: ThStage -> ThLevel
478 thLevel Comp = topLevel
479 thLevel (Splice l) = l
480 thLevel (Brack l _ _) = l
483 checkWellStaged :: SDoc -- What the stage check is for
484 -> ThLevel -- Binding level
485 -> ThStage -- Use stage
486 -> TcM () -- Fail if badly staged, adding an error
487 checkWellStaged pp_thing bind_lvl use_stage
488 | bind_lvl <= use_lvl -- OK!
491 | bind_lvl == topLevel -- GHC restriction on top level splices
493 sep [ptext SLIT("GHC stage restriction:") <+> pp_thing,
494 nest 2 (ptext SLIT("is used in a top-level splice, and must be imported, not defined locally"))]
496 | otherwise -- Badly staged
498 ptext SLIT("Stage error:") <+> pp_thing <+>
499 hsep [ptext SLIT("is bound at stage") <+> ppr bind_lvl,
500 ptext SLIT("but used at stage") <+> ppr use_lvl]
502 use_lvl = thLevel use_stage
505 topIdLvl :: Id -> ThLevel
506 -- Globals may either be imported, or may be from an earlier "chunk"
507 -- (separated by declaration splices) of this module. The former
508 -- *can* be used inside a top-level splice, but the latter cannot.
509 -- Hence we give the former impLevel, but the latter topLevel
513 -- By the time we are prcessing the $(f x), the binding for "x"
514 -- will be in the global env, not the local one.
515 topIdLvl id | isLocalId id = topLevel
516 | otherwise = impLevel
518 -- Indicates the legal transitions on bracket( [| |] ).
519 bracketOK :: ThStage -> Maybe ThLevel
520 bracketOK (Brack _ _ _) = Nothing -- Bracket illegal inside a bracket
521 bracketOK stage = Just (thLevel stage + 1)
523 -- Indicates the legal transitions on splice($).
524 spliceOK :: ThStage -> Maybe ThLevel
525 spliceOK (Splice _) = Nothing -- Splice illegal inside splice
526 spliceOK stage = Just (thLevel stage - 1)
528 tcMetaTy :: Name -> TcM Type
529 -- Given the name of a Template Haskell data type,
531 -- E.g. given the name "Expr" return the type "Expr"
533 = tcLookupTyCon tc_name `thenM` \ t ->
534 returnM (mkTyConApp t [])
538 %************************************************************************
540 \subsection{The InstInfo type}
542 %************************************************************************
544 The InstInfo type summarises the information in an instance declaration
546 instance c => k (t tvs) where b
548 It is used just for *local* instance decls (not ones from interface files).
549 But local instance decls includes
552 as well as explicit user written ones.
557 iSpec :: Instance, -- Includes the dfun id. Its forall'd type
558 iBinds :: InstBindings -- variables scope over the stuff in InstBindings!
561 iDFunId :: InstInfo -> DFunId
562 iDFunId info = instanceDFunId (iSpec info)
565 = VanillaInst -- The normal case
566 (LHsBinds Name) -- Bindings
567 [LSig Name] -- User pragmas recorded for generating
568 -- specialised instances
571 TyCon -- tycon for the newtype
572 -- Used for deriving instances of newtypes, where the
573 [Type] -- witness dictionary is identical to the argument
574 -- dictionary. Hence no bindings, no pragmas
575 -- The [Type] are the representation types
576 -- See notes in TcDeriv
578 pprInstInfo info = vcat [ptext SLIT("InstInfo:") <+> ppr (idType (iDFunId info))]
580 pprInstInfoDetails info = pprInstInfo info $$ nest 2 (details (iBinds info))
582 details (VanillaInst b _) = pprLHsBinds b
583 details (NewTypeDerived _ _) = text "Derived from the representation type"
585 simpleInstInfoClsTy :: InstInfo -> (Class, Type)
586 simpleInstInfoClsTy info = case instanceHead (iSpec info) of
587 (_, _, cls, [ty]) -> (cls, ty)
589 simpleInstInfoTy :: InstInfo -> Type
590 simpleInstInfoTy info = snd (simpleInstInfoClsTy info)
592 simpleInstInfoTyCon :: InstInfo -> TyCon
593 -- Gets the type constructor for a simple instance declaration,
594 -- i.e. one of the form instance (...) => C (T a b c) where ...
595 simpleInstInfoTyCon inst = tcTyConAppTyCon (simpleInstInfoTy inst)
598 Make a name for the dict fun for an instance decl. It's an *external*
599 name, like otber top-level names, and hence must be made with newGlobalBinder.
602 newDFunName :: Class -> [Type] -> SrcLoc -> TcM Name
603 newDFunName clas (ty:_) loc
604 = do { index <- nextDFunIndex
605 ; is_boot <- tcIsHsBoot
607 ; let info_string = occNameString (getOccName clas) ++
608 occNameString (getDFunTyKey ty)
609 dfun_occ = mkDFunOcc info_string is_boot index
611 ; newGlobalBinder mod dfun_occ Nothing loc }
613 newDFunName clas [] loc = pprPanic "newDFunName" (ppr clas <+> ppr loc)
616 Make a name for the representation tycon of a data/newtype instance. It's an
617 *external* name, like otber top-level names, and hence must be made with
621 newFamInstTyConName :: Name -> SrcLoc -> TcM Name
622 newFamInstTyConName tc_name loc
623 = do { index <- nextDFunIndex
625 ; let occ = nameOccName tc_name
626 ; newGlobalBinder mod (mkInstTyTcOcc index occ) Nothing loc }
630 %************************************************************************
634 %************************************************************************
637 pprBinders :: [Name] -> SDoc
638 -- Used in error messages
639 -- Use quotes for a single one; they look a bit "busy" for several
640 pprBinders [bndr] = quotes (ppr bndr)
641 pprBinders bndrs = pprWithCommas ppr bndrs
644 = failWithTc (ptext SLIT("GHC internal error:") <+> quotes (ppr name) <+>
645 ptext SLIT("is not in scope"))
647 wrongThingErr expected thing name
648 = failWithTc (pprTcTyThingCategory thing <+> quotes (ppr name) <+>
649 ptext SLIT("used as a") <+> text expected)