X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcClassDcl.lhs;h=7b6765cf6222aa0cb45e37817a58e85b11a42e06;hb=77a8c0dbd5c5ad90fe483cb9ddc2b6ef36d3f4d8;hp=2372f39ada299fb054f7944886482cf5b80ecd26;hpb=d3e697b8d842bd43329d470f2bc424a6dcb88d89;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcClassDcl.lhs b/ghc/compiler/typecheck/TcClassDcl.lhs index 2372f39..7b6765c 100644 --- a/ghc/compiler/typecheck/TcClassDcl.lhs +++ b/ghc/compiler/typecheck/TcClassDcl.lhs @@ -1,66 +1,61 @@ % -% (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 ( 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(..), + mkSimpleMatch, + andMonoBinds, andMonoBindList, + isClassDecl, isClassOpSig, isPragSig, collectMonoBinders ) -import HsPragmas ( ClassPragmas(..) ) import BasicTypes ( NewOrData(..), TopLevelFlag(..), RecFlag(..) ) -import RnHsSyn ( RenamedClassDecl(..), RenamedClassPragmas(..), - RenamedClassOpSig(..), RenamedMonoBinds, - RenamedContext(..), RenamedHsDecl +import RnHsSyn ( RenamedTyClDecl, RenamedClassPragmas, + RenamedClassOpSig, RenamedMonoBinds, + RenamedContext, RenamedHsDecl, RenamedSig ) -import TcHsSyn ( TcMonoBinds ) - -import Inst ( Inst, InstOrigin(..), LIE, emptyLIE, plusLIE, newDicts, newMethod ) -import TcEnv ( TcIdOcc(..), tcAddImportedIdInfo, - tcLookupClass, tcLookupTyVar, - tcExtendGlobalTyVars ) -import TcBinds ( tcBindWithSigs, checkSigTyVars, sigCtxt, TcSigInfo(..) ) -import TcKind ( unifyKinds, TcKind ) -import TcMonad -import TcMonoType ( tcHsType, tcContext ) -import TcSimplify ( tcSimplifyAndCheck ) -import TcType ( TcType, TcTyVar, TcTyVarSet, tcInstSigTyVars, - zonkSigTyVar, tcInstSigTcType - ) -import PragmaInfo ( PragmaInfo(..) ) - -import Bag ( unionManyBags ) -import Class ( mkClass, classBigSig, Class ) -import CmdLineOpts ( opt_GlasgowExts ) -import Id ( Id, StrictnessMark(..), - mkSuperDictSelId, mkMethodSelId, - mkDefaultMethodId, getIdUnfolding, mkDataCon, - idType +import TcHsSyn ( TcMonoBinds, idsToMonoBinds ) + +import Inst ( Inst, InstOrigin(..), LIE, emptyLIE, plusLIE, plusLIEs, newDicts, newMethod ) +import TcEnv ( TcId, ValueEnv, TyThing(..), TyThingDetails(..), tcAddImportedIdInfo, + tcLookupTy, tcExtendTyVarEnvForMeths, tcExtendGlobalTyVars, + tcExtendLocalValEnv, tcExtendTyVarEnv ) -import CoreUnfold ( getUnfoldingTemplate ) -import IdInfo -import Name ( Name, isLocallyDefined, OccName, nameOccName, - NamedThing(..) ) +import TcBinds ( tcBindWithSigs, tcSpecSigs ) +import TcTyDecls ( mkNewTyConRep ) +import TcMonoType ( tcHsSigType, tcClassContext, checkSigTyVars, sigCtxt, mkTcSig ) +import TcSimplify ( tcSimplifyAndCheck, bindInstsOfLocalFuns ) +import TcType ( TcType, TcTyVar, tcInstTyVars, tcGetTyVar, zonkTcSigTyVars ) +import TcInstUtil ( classDataCon ) +import TcMonad +import PrelInfo ( nO_METHOD_BINDING_ERROR_ID ) +import Bag ( unionManyBags, bagToList ) +import Class ( classTyVars, classBigSig, classSelIds, classTyCon, 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 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, mkClassPred, classesOfPreds, + boxedTypeKind, mkArrowKind ) -import TyVar ( mkTyVarSet, tyVarKind, TyVar ) -import TyCon ( mkDataTyCon ) -import Kind ( mkBoxedTypeKind, mkArrowKind ) -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 (noIdInfo `addSpecInfo` spec, - noIdInfo) +import Var ( tyVarKind, TyVar ) +import VarSet ( mkVarSet, emptyVarSet ) +import TyCon ( AlgTyConFlavour(..), mkClassTyCon ) +import Maybes ( seqMaybe ) +import FiniteMap ( lookupWithDefaultFM ) \end{code} @@ -98,125 +93,103 @@ Now DictTy in Type is just a form of type synomym: Death to "ExpandingDicts". +%************************************************************************ +%* * +\subsection{Type checking} +%* * +%************************************************************************ + \begin{code} -tcClassDecl1 rec_env rec_inst_mapper +tcClassDecl1 rec_env (ClassDecl context class_name - tyvar_names class_sigs def_methods pragmas - tycon_name datacon_name src_loc) - = tcAddSrcLoc src_loc $ - tcAddErrCtxt (classDeclCtxt class_name) $ - - -- CHECK ARITY 1 FOR HASKELL 1.4 + tyvar_names fundeps class_sigs def_methods pragmas + tycon_name datacon_name datacon_wkr_name sc_sel_names src_loc) + = -- CHECK ARITY 1 FOR HASKELL 1.4 checkTc (opt_GlasgowExts || length tyvar_names == 1) - (classArityErr class_name) `thenTc_` + (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) -> - - -- FORCE THE CLASS AND ITS TYVAR TO HAVE SAME KIND - unifyKinds class_kinds tyvar_kinds `thenTc_` - + tcLookupTy class_name `thenTc` \ (AClass clas) -> + let + tyvars = classTyVars clas + in + tcExtendTyVarEnv tyvars $ + -- CHECK THE CONTEXT - tcClassContext rec_class rec_tyvars context pragmas - `thenTc` \ (sc_theta, sc_tys, sc_sel_ids) -> + tcSuperClasses class_name clas + context sc_sel_names `thenTc` \ (sc_theta, sc_sel_ids) -> -- CHECK THE CLASS SIGNATURES, - mapTc (tcClassSig rec_env rec_class rec_tyvars) class_sigs - `thenTc` \ sig_stuff -> + mapTc (tcClassSig rec_env clas tyvars) + (filter isClassOpSig class_sigs) `thenTc` \ sig_stuff -> - -- MAKE THE CLASS OBJECT ITSELF + -- MAKE THE CLASS DETAILS let - (op_tys, op_sel_ids, defm_ids) = unzip3 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 - tycon - rec_class_inst_env - + (op_tys, op_items) = unzip sig_stuff + sc_tys = mkDictTys sc_theta dict_component_tys = sc_tys ++ op_tys - new_or_data = case dict_component_tys of - [_] -> NewType - other -> DataType - 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 + (classTyCon clas) + dict_con_id dict_wrap_id + + dict_con_id = mkDataConId datacon_wkr_name dict_con + dict_wrap_id = mkDataConWrapId dict_con in - returnTc clas + returnTc (class_name, ClassDetails sc_theta sc_sel_ids op_items dict_con) \end{code} - \begin{code} -tcClassContext :: Class -> [TyVar] +tcSuperClasses :: Name -> Class -> RenamedContext -- class context - -> RenamedClassPragmas -- pragmas for superclasses - -> TcM s (ThetaType, -- the superclass context - [Type], -- types of the superclass dictionaries + -> [Name] -- Names for superclass selectors + -> TcM s (ClassContext, -- the superclass context [Id]) -- superclass selector Ids -tcClassContext rec_class rec_tyvars context pragmas +tcSuperClasses class_name clas context sc_sel_names = -- Check the context. -- The renamer has already checked that the context mentions -- only the type variable of the class decl. - tcContext context `thenTc` \ sc_theta -> - let - sc_tys = [mkDictTy sc tys | (sc,tys) <- sc_theta] - 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` [1..]) `thenTc` \ sc_sel_ids -> + -- For std Haskell check that the context constrains only tyvars + (if opt_GlasgowExts then + returnTc () + else + mapTc_ check_constraint context + ) `thenTc_` + -- Context is already kind-checked + tcClassContext context `thenTc` \ sc_theta -> + let + sc_sel_ids = [mkDictSelId sc_name clas | sc_name <- sc_sel_names] + in -- Done - returnTc (sc_theta, sc_tys, sc_sel_ids) + returnTc (sc_theta, sc_sel_ids) where - rec_tyvar_tys = mkTyVarTys rec_tyvars + check_constraint sc@(HsPClass c tys) + = checkTc (all is_tyvar tys) (superClassErr class_name sc) - 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) + is_tyvar (HsTyVar _) = 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) +tcClassSig rec_env clas clas_tyvars + (ClassOpSig op_name dm_name explicit_dm op_ty src_loc) = tcAddSrcLoc src_loc $ -- Check the type signature. NB that the envt *already has* @@ -224,24 +197,18 @@ 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 -> + tcHsSigType op_ty `thenTc` \ local_ty -> let - global_ty = mkSigmaTy rec_clas_tyvars - [(rec_clas, mkTyVarTys rec_clas_tyvars)] + global_ty = mkSigmaTy clas_tyvars + [mkClassPred clas (mkTyVarTys 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 clas + dm_id = mkDefaultMethodId dm_name clas global_ty + final_dm_id = tcAddImportedIdInfo rec_env dm_id in - returnTc (local_ty, sel_id, maybe_dm_id) + returnTc (local_ty, (sel_id, final_dm_id, explicit_dm)) \end{code} @@ -269,12 +236,12 @@ 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) -> @@ -285,11 +252,11 @@ 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) @@ -297,25 +264,27 @@ tcClassDecl2 (ClassDecl context class_name | otherwise -- It is locally defined = recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $ tcAddSrcLoc src_loc $ + tcLookupTy class_name `thenNF_Tc` \ (AClass 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} %************************************************************************ @@ -340,23 +309,11 @@ 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} @@ -395,70 +352,92 @@ 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 - `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 + zonkTcSigTyVars 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 @@ -468,42 +447,116 @@ 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) - -> TcM s (TcMonoBinds s, LIE s, (LIE s, TcIdOcc s)) - -tcMethodBind clas origin inst_tys inst_tyvars sel_id meth_bind - = 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 - 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 (\_ -> NoPragmaInfo) - ) `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_` - - returnTc (binds, insts, meth) + -- + -- We do this for each method independently to localise error messages + tcAddErrCtxtM (sigCtxt sig_msg inst_tyvars inst_theta (idType meth_id)) $ + checkSigTyVars inst_tyvars emptyVarSet `thenTc_` + + 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 (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 + = FunMonoBind local_meth_name + False -- Not infix decl + [mkSimpleMatch [] (default_expr loc) Nothing loc] + 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 @@ -512,18 +565,21 @@ 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 (ppr 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}