X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcClassDcl.lhs;h=a5aee6b6d5277467e6b7714922eb5d528b066d94;hb=cfbedcecad9f9c4241fa1313e73468fd95db76b3;hp=6cc6a7a811e346036e043b869a2321e8c259a77f;hpb=83817d01dff687643eee23218435b968ba358a25;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcClassDcl.lhs b/ghc/compiler/typecheck/TcClassDcl.lhs index 6cc6a7a..a5aee6b 100644 --- a/ghc/compiler/typecheck/TcClassDcl.lhs +++ b/ghc/compiler/typecheck/TcClassDcl.lhs @@ -1,67 +1,70 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1995 +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[TcClassDcl]{Typechecking class declarations} \begin{code} -module TcClassDcl ( tcClassDecl1, tcClassDecls2, tcMethodBind, badMethodErr ) where +module TcClassDcl ( kcClassDecl, tcClassDecl1, tcClassDecls2, mkImplicitClassBinds, + tcMethodBind, checkFromThisClass + ) where #include "HsVersions.h" -import HsSyn ( HsDecl(..), ClassDecl(..), Sig(..), MonoBinds(..), - InPat(..), andMonoBinds, getTyVarName +import HsSyn ( HsDecl(..), TyClDecl(..), Sig(..), MonoBinds(..), + InPat(..), HsBinds(..), GRHSs(..), + HsExpr(..), HsLit(..), HsType(..), HsPred(..), + pprHsClassAssertion, unguardedRHS, + andMonoBinds, andMonoBindList, getTyVarName, + isClassDecl, isClassOpSig, isPragSig, collectMonoBinders ) import HsPragmas ( ClassPragmas(..) ) import BasicTypes ( NewOrData(..), TopLevelFlag(..), RecFlag(..) ) -import RnHsSyn ( RenamedClassDecl(..), RenamedClassPragmas(..), - RenamedClassOpSig(..), RenamedMonoBinds, - RenamedContext(..), RenamedHsDecl, RenamedSig +import RnHsSyn ( RenamedTyClDecl, RenamedClassPragmas, + RenamedClassOpSig, RenamedMonoBinds, + RenamedContext, RenamedHsDecl, RenamedSig ) -import TcHsSyn ( TcMonoBinds ) +import TcHsSyn ( TcMonoBinds, idsToMonoBinds ) -import Inst ( Inst, InstOrigin(..), LIE, emptyLIE, plusLIE, newDicts, newMethod ) -import TcEnv ( TcIdOcc(..), tcAddImportedIdInfo, - tcLookupClass, tcLookupTyVar, - tcExtendGlobalTyVars, tcExtendLocalValEnv +import Inst ( Inst, InstOrigin(..), LIE, emptyLIE, plusLIE, plusLIEs, newDicts, newMethod ) +import TcEnv ( TcId, ValueEnv, TcTyThing(..), tcAddImportedIdInfo, + tcLookupClass, tcLookupTy, tcExtendTyVarEnvForMeths, tcExtendGlobalTyVars, + tcExtendLocalValEnv ) -import TcBinds ( tcBindWithSigs, checkSigTyVars, sigCtxt, tcPragmaSigs, TcSigInfo(..) ) -import TcKind ( unifyKinds, TcKind ) +import TcBinds ( tcBindWithSigs, tcSpecSigs ) +import TcTyDecls ( mkNewTyConRep ) +import TcUnify ( unifyKinds ) import TcMonad -import TcMonoType ( tcHsType, tcContext ) -import TcSimplify ( tcSimplifyAndCheck ) -import TcType ( TcType, TcTyVar, TcTyVarSet, tcInstSigTyVars, - zonkSigTyVar, tcInstSigTcType +import TcMonoType ( kcHsType, tcHsTopType, tcExtendTopTyVarScope, + tcContext, checkSigTyVars, sigCtxt, mkTcSig ) +import TcSimplify ( tcSimplifyAndCheck, bindInstsOfLocalFuns ) +import TcType ( TcType, TcTyVar, tcInstTyVars, zonkTcTyVarBndr, tcGetTyVar ) +import TcInstUtil ( classDataCon ) +import PrelInfo ( nO_METHOD_BINDING_ERROR_ID ) import FieldLabel ( firstFieldLabelTag ) -import Bag ( unionManyBags ) -import Class ( mkClass, classBigSig, Class ) -import CmdLineOpts ( opt_GlasgowExts ) -import MkId ( mkDataCon, mkSuperDictSelId, - mkMethodSelId, mkDefaultMethodId - ) -import Id ( Id, StrictnessMark(..), - getIdUnfolding, idType - ) -import CoreUnfold ( getUnfoldingTemplate ) +import Bag ( unionManyBags, bagToList ) +import Class ( mkClass, classBigSig, classSelIds, Class, ClassOpItem ) +import CmdLineOpts ( opt_GlasgowExts, opt_WarnMissingMethods ) +import MkId ( mkDictSelId, mkDataConId, mkDataConWrapId, mkDefaultMethodId ) +import DataCon ( mkDataCon, dataConId, dataConWrapId, notMarkedStrict ) +import Id ( Id, setInlinePragma, idUnfolding, idType, idName ) +import CoreUnfold ( unfoldingTemplate ) import IdInfo -import Name ( Name, isLocallyDefined, OccName, nameOccName, - NamedThing(..) ) +import Name ( Name, nameOccName, isLocallyDefined, NamedThing(..) ) +import NameSet ( emptyNameSet ) import Outputable -import Type ( mkFunTy, mkTyVarTy, mkTyVarTys, mkDictTy, splitRhoTy, - mkSigmaTy, mkForAllTys, Type, ThetaType +import Type ( Type, ThetaType, ClassContext, + mkFunTy, mkTyVarTy, mkTyVarTys, mkDictTy, mkDictTys, + mkSigmaTy, mkForAllTys, mkClassPred, classesOfPreds, + boxedTypeKind, mkArrowKind ) -import TyVar ( mkTyVarSet, tyVarKind, TyVar ) -import TyCon ( mkDataTyCon ) -import Kind ( mkBoxedTypeKind, mkArrowKind ) +import Var ( tyVarKind, TyVar ) +import VarSet ( mkVarSet, emptyVarSet ) +import TyCon ( AlgTyConFlavour(..), mkClassTyCon ) import Unique ( Unique, Uniquable(..) ) import Util -import Maybes ( assocMaybe, maybeToBool ) - - --- import TcPragmas ( tcGenPragmas, tcClassOpPragmas ) -tcGenPragmas ty id ps = returnNF_Tc noIdInfo -tcClassOpPragmas ty sel def spec ps = returnNF_Tc (spec `setSpecInfo` noIdInfo, - noIdInfo) +import Maybes ( seqMaybe ) +import FiniteMap ( lookupWithDefaultFM ) \end{code} @@ -99,125 +102,178 @@ Now DictTy in Type is just a form of type synomym: Death to "ExpandingDicts". -\begin{code} -tcClassDecl1 rec_env rec_inst_mapper - (ClassDecl context class_name - tyvar_names class_sigs def_methods pragmas - tycon_name datacon_name src_loc) - = tcAddSrcLoc src_loc $ - tcAddErrCtxt (classDeclCtxt class_name) $ +%************************************************************************ +%* * +\subsection{Kind checking} +%* * +%************************************************************************ - -- CHECK ARITY 1 FOR HASKELL 1.4 +\begin{code} +kcClassDecl (ClassDecl context class_name + tyvar_names fundeps class_sigs def_methods pragmas + _ _ _ _ src_loc) + = -- CHECK ARITY 1 FOR HASKELL 1.4 checkTc (opt_GlasgowExts || length tyvar_names == 1) (classArityErr class_name) `thenTc_` - -- LOOK THINGS UP IN THE ENVIRONMENT - tcLookupClass class_name `thenTc` \ (class_kinds, rec_class) -> - mapAndUnzipNF_Tc (tcLookupTyVar . getTyVarName) tyvar_names - `thenNF_Tc` \ (tyvar_kinds, rec_tyvars) -> + -- Get the (mutable) class kind + tcLookupTy class_name `thenNF_Tc` \ (kind, _, _) -> + + -- Make suitable tyvars and do kind checking + -- The net effect is to mutate the class kind + tcExtendTopTyVarScope kind tyvar_names $ \ _ _ -> + tcContext context `thenTc_` + mapTc kc_sig the_class_sigs `thenTc_` - -- FORCE THE CLASS AND ITS TYVAR TO HAVE SAME KIND - unifyKinds class_kinds tyvar_kinds `thenTc_` + returnTc () + where + the_class_sigs = filter isClassOpSig class_sigs + + kc_sig (ClassOpSig _ _ _ op_ty loc) = tcAddSrcLoc loc (kcHsType op_ty) +\end{code} + +%************************************************************************ +%* * +\subsection{Type checking} +%* * +%************************************************************************ + +\begin{code} +tcClassDecl1 rec_env rec_inst_mapper rec_vrcs + (ClassDecl context class_name + tyvar_names fundeps class_sigs def_methods pragmas + tycon_name datacon_name datacon_wkr_name sc_sel_names src_loc) + = -- LOOK THINGS UP IN THE ENVIRONMENT + tcLookupTy class_name `thenTc` \ (class_kind, _, AClass rec_class) -> + tcExtendTopTyVarScope class_kind tyvar_names $ \ tyvars _ -> + -- The class kind is by now immutable + -- CHECK THE CONTEXT - tcClassContext rec_class rec_tyvars context pragmas +-- traceTc (text "tcClassCtxt" <+> ppr class_name) `thenTc_` + tcClassContext class_name rec_class tyvars context sc_sel_names `thenTc` \ (sc_theta, sc_tys, sc_sel_ids) -> +-- traceTc (text "tcClassCtxt done" <+> ppr class_name) `thenTc_` + + -- CHECK THE FUNCTIONAL DEPENDENCIES, + tcFundeps fundeps `thenTc` \ fds -> -- CHECK THE CLASS SIGNATURES, - mapTc (tcClassSig rec_env rec_class rec_tyvars) class_sigs + mapTc (tcClassSig rec_env rec_class tyvars) + (filter isClassOpSig class_sigs) `thenTc` \ sig_stuff -> -- MAKE THE CLASS OBJECT ITSELF let - (op_tys, op_sel_ids, defm_ids) = unzip3 sig_stuff + (op_tys, op_items) = unzip sig_stuff rec_class_inst_env = rec_inst_mapper rec_class - clas = mkClass (getName class_name) rec_tyvars - sc_theta sc_sel_ids op_sel_ids defm_ids + clas = mkClass class_name tyvars fds + sc_theta sc_sel_ids op_items tycon rec_class_inst_env dict_component_tys = sc_tys ++ op_tys new_or_data = case dict_component_tys of - [_] -> NewType - other -> DataType + [_] -> NewTyCon (mkNewTyConRep tycon) + other -> DataTyCon - dict_con_id = mkDataCon datacon_name - [NotMarkedStrict | _ <- dict_component_tys] + dict_con = mkDataCon datacon_name + [notMarkedStrict | _ <- dict_component_tys] [{- No labelled fields -}] - rec_tyvars + tyvars [{-No context-}] [{-No existential tyvars-}] [{-Or context-}] dict_component_tys - tycon - - tycon = mkDataTyCon tycon_name - (foldr (mkArrowKind . tyVarKind) mkBoxedTypeKind rec_tyvars) - rec_tyvars - [] -- No context - [dict_con_id] -- Constructors - [] -- No derivings - (Just clas) -- Yes! It's a dictionary - new_or_data - NonRecursive + tycon dict_con_id dict_wrap_id + + dict_con_id = mkDataConId datacon_wkr_name dict_con + dict_wrap_id = mkDataConWrapId dict_con + + argvrcs = lookupWithDefaultFM rec_vrcs (pprPanic "tcClassDecl1: argvrcs:" $ + ppr tycon_name) + tycon_name + + tycon = mkClassTyCon tycon_name + class_kind + tyvars + argvrcs + dict_con -- Constructors + clas -- Yes! It's a dictionary + new_or_data in returnTc clas \end{code} +\begin{code} +tcFundeps = mapTc tc_fundep +tc_fundep (us, vs) = + mapTc tc_fd_tyvar us `thenTc` \ us' -> + mapTc tc_fd_tyvar vs `thenTc` \ vs' -> + returnTc (us', vs') +tc_fd_tyvar v = + tcLookupTy v `thenTc` \(_, _, thing) -> + case thing of + ATyVar tv -> returnTc tv + -- ZZ else should fail more gracefully +\end{code} \begin{code} -tcClassContext :: Class -> [TyVar] +tcClassContext :: Name -> Class -> [TyVar] -> RenamedContext -- class context - -> RenamedClassPragmas -- pragmas for superclasses - -> TcM s (ThetaType, -- the superclass context + -> [Name] -- Names for superclass selectors + -> TcM s (ClassContext, -- the superclass context [Type], -- types of the superclass dictionaries [Id]) -- superclass selector Ids -tcClassContext rec_class rec_tyvars context pragmas +tcClassContext class_name rec_class rec_tyvars context sc_sel_names = -- Check the context. -- The renamer has already checked that the context mentions -- only the type variable of the class decl. + + -- For std Haskell check that the context constrains only tyvars + (if opt_GlasgowExts then + returnTc [] + else + mapTc check_constraint context + ) `thenTc_` + tcContext context `thenTc` \ sc_theta -> + let - sc_tys = [mkDictTy sc tys | (sc,tys) <- sc_theta] + sc_theta' = classesOfPreds sc_theta + sc_tys = mkDictTys sc_theta' + sc_sel_ids = zipWithEqual "tcClassContext" mk_super_id sc_sel_names sc_tys in - - -- Make super-class selector ids - -- We number them off, 1, 2, 3 etc so that we can construct - -- names for the selectors. Thus - -- class (C a, C b) => D a b where ... - -- gives superclass selectors - -- D_sc1, D_sc2 - -- (We used to call them D_C, but now we can have two different - -- superclasses both called C!) - mapTc mk_super_id (sc_theta `zip` [firstFieldLabelTag..]) `thenTc` \ sc_sel_ids -> - -- Done - returnTc (sc_theta, sc_tys, sc_sel_ids) + returnTc (sc_theta', sc_tys, sc_sel_ids) where rec_tyvar_tys = mkTyVarTys rec_tyvars - mk_super_id ((super_class, tys), index) - = tcGetUnique `thenNF_Tc` \ uniq -> - let - ty = mkForAllTys rec_tyvars $ - mkFunTy (mkDictTy rec_class rec_tyvar_tys) (mkDictTy super_class tys) - in - returnTc (mkSuperDictSelId uniq rec_class index ty) + mk_super_id name dict_ty + = mkDictSelId name rec_class ty + where + ty = mkForAllTys rec_tyvars $ + mkFunTy (mkDictTy rec_class rec_tyvar_tys) dict_ty + + check_constraint (HsPClass c tys) = checkTc (all is_tyvar tys) + (superClassErr class_name (c, tys)) + is_tyvar (MonoTyVar _) = True + is_tyvar other = False -tcClassSig :: TcEnv s -- Knot tying only! + +tcClassSig :: ValueEnv -- Knot tying only! -> Class -- ...ditto... -> [TyVar] -- The class type variable, used for error check only -> RenamedClassOpSig -> TcM s (Type, -- Type of the method - Id, -- selector id - Maybe Id) -- default-method ids + ClassOpItem) -- Selector Id, default-method Id, True if explicit default binding + tcClassSig rec_env rec_clas rec_clas_tyvars - (ClassOpSig op_name maybe_dm_name - op_ty - src_loc) + (ClassOpSig op_name dm_name explicit_dm + op_ty src_loc) = tcAddSrcLoc src_loc $ -- Check the type signature. NB that the envt *already has* @@ -225,24 +281,20 @@ tcClassSig rec_env rec_clas rec_clas_tyvars -- NB: Renamer checks that the class type variable is mentioned in local_ty, -- and that it is not constrained by theta - tcHsType op_ty `thenTc` \ local_ty -> +-- traceTc (text "tcClassSig" <+> ppr op_name) `thenTc_` + tcHsTopType op_ty `thenTc` \ local_ty -> let global_ty = mkSigmaTy rec_clas_tyvars - [(rec_clas, mkTyVarTys rec_clas_tyvars)] + [mkClassPred rec_clas (mkTyVarTys rec_clas_tyvars)] local_ty - in -- Build the selector id and default method id - let - sel_id = mkMethodSelId op_name rec_clas global_ty - maybe_dm_id = case maybe_dm_name of - Nothing -> Nothing - Just dm_name -> let - dm_id = mkDefaultMethodId dm_name rec_clas global_ty - in - Just (tcAddImportedIdInfo rec_env dm_id) + sel_id = mkDictSelId op_name rec_clas global_ty + dm_id = mkDefaultMethodId dm_name rec_clas global_ty + final_dm_id = tcAddImportedIdInfo rec_env dm_id in - returnTc (local_ty, sel_id, maybe_dm_id) +-- traceTc (text "tcClassSig done" <+> ppr op_name) `thenTc_` + returnTc (local_ty, (sel_id, final_dm_id, explicit_dm)) \end{code} @@ -270,12 +322,12 @@ each local class decl. \begin{code} tcClassDecls2 :: [RenamedHsDecl] - -> NF_TcM s (LIE s, TcMonoBinds s) + -> NF_TcM s (LIE, TcMonoBinds) tcClassDecls2 decls = foldr combine (returnNF_Tc (emptyLIE, EmptyMonoBinds)) - [tcClassDecl2 cls_decl | ClD cls_decl <- decls] + [tcClassDecl2 cls_decl | TyClD cls_decl <- decls, isClassDecl cls_decl] where combine tc1 tc2 = tc1 `thenNF_Tc` \ (lie1, binds1) -> tc2 `thenNF_Tc` \ (lie2, binds2) -> @@ -286,11 +338,11 @@ tcClassDecls2 decls @tcClassDecl2@ is the business end of things. \begin{code} -tcClassDecl2 :: RenamedClassDecl -- The class declaration - -> NF_TcM s (LIE s, TcMonoBinds s) +tcClassDecl2 :: RenamedTyClDecl -- The class declaration + -> NF_TcM s (LIE, TcMonoBinds) tcClassDecl2 (ClassDecl context class_name - tyvar_names class_sigs default_binds pragmas _ _ src_loc) + tyvar_names _ class_sigs default_binds pragmas _ _ _ _ src_loc) | not (isLocallyDefined class_name) = returnNF_Tc (emptyLIE, EmptyMonoBinds) @@ -298,25 +350,27 @@ tcClassDecl2 (ClassDecl context class_name | otherwise -- It is locally defined = recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $ tcAddSrcLoc src_loc $ + tcLookupClass class_name `thenNF_Tc` \ clas -> + tcDefaultMethodBinds clas default_binds class_sigs +\end{code} - -- Get the relevant class - tcLookupClass class_name `thenTc` \ (_, clas) -> - let - (tyvars, sc_theta, sc_sel_ids, op_sel_ids, defm_ids) = classBigSig clas - +\begin{code} +mkImplicitClassBinds :: [Class] -> NF_TcM s ([Id], TcMonoBinds) +mkImplicitClassBinds classes + = returnNF_Tc (concat cls_ids_s, andMonoBindList binds_s) -- The selector binds are already in the selector Id's unfoldings - sel_binds = [ CoreMonoBind (RealId sel_id) (getUnfoldingTemplate (getIdUnfolding sel_id)) - | sel_id <- sc_sel_ids ++ op_sel_ids, - isLocallyDefined sel_id - ] + where + (cls_ids_s, binds_s) = unzip (map mk_implicit classes) - final_sel_binds = andMonoBinds sel_binds - in - -- Generate bindings for the default methods - tcDefaultMethodBinds clas default_binds `thenTc` \ (const_insts, meth_binds) -> + mk_implicit clas = (all_cls_ids, binds) + where + dict_con = classDataCon clas + all_cls_ids = dataConId dict_con : cls_ids + cls_ids = dataConWrapId dict_con : classSelIds clas - returnTc (const_insts, - final_sel_binds `AndMonoBinds` meth_binds) + -- The wrapper and selectors get bindings, the worker does not + binds | isLocallyDefined clas = idsToMonoBinds cls_ids + | otherwise = EmptyMonoBinds \end{code} %************************************************************************ @@ -341,23 +395,11 @@ we get the default methods: defm.Foo.op1 :: forall a. Foo a => a -> Bool defm.Foo.op1 = /\a -> \dfoo -> \x -> True -====================== OLD ================== -\begin{verbatim} -defm.Foo.op2 :: forall a, b. (Foo a, Ord b) => a -> b -> b -> b -defm.Foo.op2 = /\ a b -> \ dfoo dord -> \x y z -> - if (op1 a dfoo x) && (< b dord y z) then y else z -\end{verbatim} -Notice that, like all ids, the foralls of defm.Foo.op2 are at the top. -====================== END OF OLD =================== - -NEW: -\begin{verbatim} defm.Foo.op2 :: forall a. Foo a => forall b. Ord b => a -> b -> b -> b defm.Foo.op2 = /\ a -> \ dfoo -> /\ b -> \ dord -> \x y z -> if (op1 a dfoo x) && (< b dord y z) then y else z \end{verbatim} - When we come across an instance decl, we may need to use the default methods: \begin{verbatim} @@ -396,70 +438,92 @@ dfun.Foo.List tcDefaultMethodBinds :: Class -> RenamedMonoBinds - -> TcM s (LIE s, TcMonoBinds s) + -> [RenamedSig] + -> TcM s (LIE, TcMonoBinds) + +tcDefaultMethodBinds clas default_binds sigs + = -- Check that the default bindings come from this class + checkFromThisClass clas op_items default_binds `thenNF_Tc_` + + -- Do each default method separately + -- For Hugs compatibility we make a default-method for every + -- class op, regardless of whether or not the programmer supplied an + -- explicit default decl for the class. GHC will actually never + -- call the default method for such operations, because it'll whip up + -- a more-informative default method at each instance decl. + mapAndUnzipTc tc_dm op_items `thenTc` \ (defm_binds, const_lies) -> + + returnTc (plusLIEs const_lies, andMonoBindList defm_binds) + where + prags = filter isPragSig sigs -tcDefaultMethodBinds clas default_binds - = -- Construct suitable signatures - tcInstSigTyVars tyvars `thenNF_Tc` \ (clas_tyvars, inst_tys, inst_env) -> + (tyvars, _, _, op_items) = classBigSig clas - -- Typecheck the default bindings - let - tc_dm meth_bind - | not (maybeToBool maybe_stuff) - = -- Binding for something that isn't in the class signature - failWithTc (badMethodErr bndr_name clas) - - | otherwise - = -- Normal case - tcMethodBind clas origin inst_tys clas_tyvars sel_id meth_bind [{- No prags -}] - `thenTc` \ (bind, insts, (_, local_dm_id)) -> - returnTc (bind, insts, (clas_tyvars, RealId dm_id, local_dm_id)) - where - bndr_name = case meth_bind of - FunMonoBind name _ _ _ -> name - PatMonoBind (VarPatIn name) _ _ -> name - - maybe_stuff = assocMaybe assoc_list (nameOccName bndr_name) - assoc_list = [ (getOccName sel_id, pair) - | pair@(sel_id, dm_ie) <- op_sel_ids `zip` defm_ids - ] - Just (sel_id, Just dm_id) = maybe_stuff - -- We're looking at a default-method binding, so the dm_id - -- is sure to be there! Hence the inner "Just". - in - mapAndUnzip3Tc tc_dm - (flatten default_binds []) `thenTc` \ (defm_binds, insts_needed, abs_bind_stuff) -> - - -- Check the context - newDicts origin [(clas,inst_tys)] `thenNF_Tc` \ (this_dict, [this_dict_id]) -> - let - avail_insts = this_dict - in - tcAddErrCtxt (classDeclCtxt clas) $ - mapNF_Tc zonkSigTyVar clas_tyvars `thenNF_Tc` \ clas_tyvars' -> - tcSimplifyAndCheck - (ptext SLIT("class") <+> ppr clas) - (mkTyVarSet clas_tyvars') - avail_insts - (unionManyBags insts_needed) `thenTc` \ (const_lie, dict_binds) -> + origin = ClassDeclOrigin - let - full_binds = AbsBinds - clas_tyvars' - [this_dict_id] - abs_bind_stuff - (dict_binds `AndMonoBinds` andMonoBinds defm_binds) - in - returnTc (const_lie, full_binds) + -- We make a separate binding for each default method. + -- At one time I used a single AbsBinds for all of them, thus + -- AbsBind [d] [dm1, dm2, dm3] { dm1 = ...; dm2 = ...; dm3 = ... } + -- But that desugars into + -- ds = \d -> (..., ..., ...) + -- dm1 = \d -> case ds d of (a,b,c) -> a + -- And since ds is big, it doesn't get inlined, so we don't get good + -- default methods. Better to make separate AbsBinds for each + + tc_dm op_item@(_, dm_id, _) + = tcInstTyVars tyvars `thenNF_Tc` \ (clas_tyvars, inst_tys, _) -> + let + theta = [(mkClassPred clas inst_tys)] + in + newDicts origin theta `thenNF_Tc` \ (this_dict, [this_dict_id]) -> + let + avail_insts = this_dict + in + tcExtendTyVarEnvForMeths tyvars clas_tyvars ( + tcMethodBind clas origin clas_tyvars inst_tys theta + default_binds prags False + op_item + ) `thenTc` \ (defm_bind, insts_needed, (_, local_dm_id)) -> + + tcAddErrCtxt (defltMethCtxt clas) $ + + -- tcMethodBind has checked that the class_tyvars havn't + -- been unified with each other or another type, but we must + -- still zonk them before passing them to tcSimplifyAndCheck + mapNF_Tc zonkTcTyVarBndr clas_tyvars `thenNF_Tc` \ clas_tyvars' -> + + -- Check the context + tcSimplifyAndCheck + (ptext SLIT("class") <+> ppr clas) + (mkVarSet clas_tyvars') + avail_insts + insts_needed `thenTc` \ (const_lie, dict_binds) -> + + let + full_bind = AbsBinds + clas_tyvars' + [this_dict_id] + [(clas_tyvars', dm_id, local_dm_id)] + emptyNameSet -- No inlines (yet) + (dict_binds `andMonoBinds` defm_bind) + in + returnTc (full_bind, const_lie) +\end{code} +\begin{code} +checkFromThisClass :: Class -> [ClassOpItem] -> RenamedMonoBinds -> NF_TcM s () +checkFromThisClass clas op_items mono_binds + = mapNF_Tc check_from_this_class bndrs `thenNF_Tc_` + returnNF_Tc () where - (tyvars, sc_theta, sc_sel_ids, op_sel_ids, defm_ids) = classBigSig clas - origin = ClassDeclOrigin - - flatten EmptyMonoBinds rest = rest - flatten (AndMonoBinds b1 b2) rest = flatten b1 (flatten b2 rest) - flatten a_bind rest = a_bind : rest + check_from_this_class (bndr, loc) + | nameOccName bndr `elem` sel_names = returnNF_Tc () + | otherwise = tcAddSrcLoc loc $ + addErrTc (badMethodErr bndr clas) + sel_names = [getOccName sel_id | (sel_id,_,_) <- op_items] + bndrs = bagToList (collectMonoBinders mono_binds) \end{code} + @tcMethodBind@ is used to type-check both default-method and instance-decl method declarations. We must type-check methods one at a @@ -469,49 +533,115 @@ tyvar sets. \begin{code} tcMethodBind :: Class - -> InstOrigin s - -> [TcType s] -- Instance types - -> [TcTyVar s] -- Free variables of those instance types - -- they'll be signature tyvars, and we - -- want to check that they don't bound - -> Id -- The method selector - -> RenamedMonoBinds -- Method binding (just one) - -> [RenamedSig] -- Pramgas (just for this one) - -> TcM s (TcMonoBinds s, LIE s, (LIE s, TcIdOcc s)) - -tcMethodBind clas origin inst_tys inst_tyvars sel_id meth_bind prags - = tcAddSrcLoc src_loc $ - newMethod origin (RealId sel_id) inst_tys `thenNF_Tc` \ meth@(_, TcId local_meth_id) -> - tcInstSigTcType (idType local_meth_id) `thenNF_Tc` \ (tyvars', rho_ty') -> + -> InstOrigin + -> [TcTyVar] -- Instantiated type variables for the + -- enclosing class/instance decl. + -- They'll be signature tyvars, and we + -- want to check that they don't get bound + -> [TcType] -- Instance types + -> TcThetaType -- Available theta; this could be used to check + -- the method signature, but actually that's done by + -- the caller; here, it's just used for the error message + -> RenamedMonoBinds -- Method binding (pick the right one from in here) + -> [RenamedSig] -- Pramgas (just for this one) + -> Bool -- True <=> This method is from an instance declaration + -> ClassOpItem -- The method selector and default-method Id + -> TcM s (TcMonoBinds, LIE, (LIE, TcId)) + +tcMethodBind clas origin inst_tyvars inst_tys inst_theta + meth_binds prags is_inst_decl + (sel_id, dm_id, explicit_dm) + = tcGetSrcLoc `thenNF_Tc` \ loc -> + + newMethod origin sel_id inst_tys `thenNF_Tc` \ meth@(_, meth_id) -> + mkTcSig meth_id loc `thenNF_Tc` \ sig_info -> + let - (theta', tau') = splitRhoTy rho_ty' - sig_info = TySigInfo bndr_name local_meth_id tyvars' theta' tau' src_loc + meth_name = idName meth_id + maybe_user_bind = find_bind meth_name meth_binds + + no_user_bind = case maybe_user_bind of {Nothing -> True; other -> False} + + meth_bind = case maybe_user_bind of + Just bind -> bind + Nothing -> mk_default_bind meth_name loc + + meth_prags = find_prags meth_name prags in - tcExtendLocalValEnv [bndr_name] [local_meth_id] ( - tcPragmaSigs prags - ) `thenTc` \ (prag_info_fn, prag_binds, prag_lie) -> - tcExtendGlobalTyVars inst_tyvars ( + -- Warn if no method binding, only if -fwarn-missing-methods + warnTc (is_inst_decl && opt_WarnMissingMethods && no_user_bind && not explicit_dm) + (omittedMethodWarn sel_id clas) `thenNF_Tc_` + + -- Check the bindings; first add inst_tyvars to the envt + -- so that we don't quantify over them in nested places + -- The *caller* put the class/inst decl tyvars into the envt + tcExtendGlobalTyVars (mkVarSet inst_tyvars) ( tcAddErrCtxt (methodCtxt sel_id) $ - tcBindWithSigs NotTopLevel [bndr_name] meth_bind [sig_info] - NonRecursive prag_info_fn - ) `thenTc` \ (binds, insts, _) -> + tcBindWithSigs NotTopLevel meth_bind + [sig_info] meth_prags NonRecursive + ) `thenTc` \ (binds, insts, _) -> + + + tcExtendLocalValEnv [(meth_name, meth_id)] ( + tcSpecSigs meth_prags + ) `thenTc` \ (prag_binds1, prag_lie) -> + + -- The prag_lie for a SPECIALISE pragma will mention the function + -- itself, so we have to simplify them away right now lest they float + -- outwards! + bindInstsOfLocalFuns prag_lie [meth_id] `thenTc` \ (prag_lie', prag_binds2) -> + -- Now check that the instance type variables -- (or, in the case of a class decl, the class tyvars) -- have not been unified with anything in the environment - tcAddErrCtxt (monoCtxt sel_id) ( - tcAddErrCtxt (sigCtxt sel_id) $ - checkSigTyVars inst_tyvars (idType local_meth_id) - ) `thenTc_` + tcAddErrCtxtM (sigCtxt sig_msg inst_tyvars inst_theta (idType meth_id)) $ + checkSigTyVars inst_tyvars emptyVarSet `thenTc_` - returnTc (binds `AndMonoBinds` prag_binds, - insts `plusLIE` prag_lie, + returnTc (binds `AndMonoBinds` prag_binds1 `AndMonoBinds` prag_binds2, + insts `plusLIE` prag_lie', meth) where - (bndr_name, src_loc) = case meth_bind of - FunMonoBind name _ _ loc -> (name, loc) - PatMonoBind (VarPatIn name) _ loc -> (name, loc) + sig_msg = ptext SLIT("When checking the expected type for class method") <+> ppr sel_name + + sel_name = idName sel_id + + -- The renamer just puts the selector ID as the binder in the method binding + -- but we must use the method name; so we substitute it here. Crude but simple. + find_bind meth_name (FunMonoBind op_name fix matches loc) + | op_name == sel_name = Just (FunMonoBind meth_name fix matches loc) + find_bind meth_name (PatMonoBind (VarPatIn op_name) grhss loc) + | op_name == sel_name = Just (PatMonoBind (VarPatIn meth_name) grhss loc) + find_bind meth_name (AndMonoBinds b1 b2) + = find_bind meth_name b1 `seqMaybe` find_bind meth_name b2 + find_bind meth_name other = Nothing -- Default case + + + -- Find the prags for this method, and replace the + -- selector name with the method name + find_prags meth_name [] = [] + find_prags meth_name (SpecSig name ty loc : prags) + | name == sel_name = SpecSig meth_name ty loc : find_prags meth_name prags + find_prags meth_name (InlineSig name phase loc : prags) + | name == sel_name = InlineSig meth_name phase loc : find_prags meth_name prags + find_prags meth_name (NoInlineSig name phase loc : prags) + | name == sel_name = NoInlineSig meth_name phase loc : find_prags meth_name prags + find_prags meth_name (prag:prags) = find_prags meth_name prags + + mk_default_bind local_meth_name loc + = PatMonoBind (VarPatIn local_meth_name) + (GRHSs (unguardedRHS (default_expr loc) loc) EmptyBinds Nothing) + loc + + default_expr loc + | explicit_dm = HsVar (getName dm_id) -- There's a default method + | otherwise = error_expr loc -- No default method + + error_expr loc = HsApp (HsVar (getName nO_METHOD_BINDING_ERROR_ID)) + (HsLit (HsString (_PK_ (error_msg loc)))) + + error_msg loc = showSDoc (hcat [ppr loc, text "|", ppr sel_id ]) \end{code} Contexts and errors @@ -520,18 +650,21 @@ Contexts and errors classArityErr class_name = ptext SLIT("Too many parameters for class") <+> quotes (ppr class_name) -classDeclCtxt class_name - = ptext SLIT("In the class declaration for") <+> quotes (ppr class_name) +superClassErr class_name sc + = ptext SLIT("Illegal superclass constraint") <+> quotes (pprHsClassAssertion sc) + <+> ptext SLIT("in declaration for class") <+> quotes (ppr class_name) + +defltMethCtxt class_name + = ptext SLIT("When checking the default methods for class") <+> quotes (ppr class_name) methodCtxt sel_id = ptext SLIT("In the definition for method") <+> quotes (ppr sel_id) -monoCtxt sel_id - = sep [ptext SLIT("Probable cause: the right hand side of") <+> quotes (ppr sel_id), - nest 4 (ptext SLIT("mentions a top-level variable subject to the dreaded monomorphism restriction")) - ] - badMethodErr bndr clas = hsep [ptext SLIT("Class"), quotes (ppr clas), ptext SLIT("does not have a method"), quotes (ppr bndr)] + +omittedMethodWarn sel_id clas + = sep [ptext SLIT("No explicit method nor default method for") <+> quotes (ppr sel_id), + ptext SLIT("in an instance declaration for") <+> quotes (ppr clas)] \end{code}