X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcClassDcl.lhs;h=d4690c68f5939a20fbf7386ec0e6419e30222950;hb=1bba522f5ec82c43abd2ba4e84127b9c915dd020;hp=da8ea9562cb28c01cdbeb746a0f0bb2338a3e006;hpb=8de16184643ea3c2f9f30b5eaed18db6ef247760;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcClassDcl.lhs b/ghc/compiler/typecheck/TcClassDcl.lhs index da8ea95..d4690c6 100644 --- a/ghc/compiler/typecheck/TcClassDcl.lhs +++ b/ghc/compiler/typecheck/TcClassDcl.lhs @@ -1,66 +1,51 @@ % -% (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} -#include "HsVersions.h" - -module TcClassDcl ( tcClassDecl1, tcClassDecls2 ) where +module TcClassDcl ( tcClassDecl1, tcClassDecls2, mkImplicitClassBinds, + tcMethodBind, checkFromThisClass + ) where -IMP_Ubiq() +#include "HsVersions.h" -import HsSyn ( HsDecl(..), ClassDecl(..), HsBinds(..), Bind(..), MonoBinds(..), - Match(..), GRHSsAndBinds(..), GRHS(..), HsExpr(..), - DefaultDecl, TyDecl, InstDecl, IfaceSig, Fixity, - HsLit(..), OutPat(..), Sig(..), HsType(..), HsTyVar, - Stmt, Qualifier, ArithSeqInfo, InPat, Fake ) -import HsTypes ( getTyVarName ) -import HsPragmas ( ClassPragmas(..) ) -import RnHsSyn ( RenamedClassDecl(..), RenamedClassPragmas(..), - RenamedClassOpSig(..), SYN_IE(RenamedMonoBinds), - RenamedGenPragmas(..), RenamedContext(..), SYN_IE(RenamedHsDecl) +import HsSyn ( HsDecl(..), TyClDecl(..), Sig(..), MonoBinds(..), + HsExpr(..), HsLit(..), HsType(..), HsPred(..), + mkSimpleMatch, andMonoBinds, andMonoBindList, + isClassDecl, isClassOpSig, isPragSig, collectMonoBinders + ) +import BasicTypes ( TopLevelFlag(..), RecFlag(..) ) +import RnHsSyn ( RenamedTyClDecl, + RenamedClassOpSig, RenamedMonoBinds, + RenamedContext, RenamedHsDecl, RenamedSig ) -import TcHsSyn ( TcIdOcc(..), SYN_IE(TcHsBinds), SYN_IE(TcMonoBinds), SYN_IE(TcExpr), - mkHsTyApp, mkHsTyLam, mkHsDictApp, mkHsDictLam, tcIdType ) +import TcHsSyn ( TcMonoBinds, idsToMonoBinds ) -import Inst ( Inst, InstOrigin(..), SYN_IE(LIE), emptyLIE, plusLIE, newDicts, newMethod ) -import TcEnv ( tcLookupClass, tcLookupTyVar, tcLookupTyCon, newLocalIds, tcExtendGlobalTyVars ) -import TcInstDcls ( processInstBinds ) -import TcKind ( unifyKind, TcKind ) -import TcMonad -import TcMonoType ( tcHsType, tcContext ) -import TcSimplify ( tcSimplifyAndCheck ) -import TcType ( SYN_IE(TcType), SYN_IE(TcTyVar), tcInstType, tcInstSigTyVars, tcInstSigType ) - -import Bag ( foldBag, unionManyBags ) -import Class ( GenClass, GenClassOp, mkClass, mkClassOp, classBigSig, - classOps, classOpString, classOpLocalType, - classOpTagByOccName, SYN_IE(ClassOp) +import Inst ( InstOrigin(..), LIE, emptyLIE, plusLIE, plusLIEs, newDicts, newMethod ) +import TcEnv ( TcId, ValueEnv, TyThing(..), TyThingDetails(..), tcAddImportedIdInfo, + tcLookupTy, tcExtendTyVarEnvForMeths, tcExtendGlobalTyVars, + tcExtendLocalValEnv, tcExtendTyVarEnv, newDefaultMethodName ) -import Id ( GenId, mkSuperDictSelId, mkMethodSelId, mkDefaultMethodId, getIdUnfolding, - idType ) -import CoreUnfold ( getUnfoldingTemplate ) -import IdInfo -import Name ( Name, isLocallyDefined, moduleString, modAndOcc, nameString ) -import PrelVals ( nO_DEFAULT_METHOD_ERROR_ID ) -import PprStyle -import Pretty -import PprType ( GenType, GenTyVar, GenClassOp ) -import SpecEnv ( SpecEnv ) -import SrcLoc ( mkGeneratedSrcLoc ) -import Type ( mkFunTy, mkTyVarTy, mkTyVarTys, mkDictTy, - mkForAllTy, mkSigmaTy, splitSigmaTy) -import TysWiredIn ( stringTy ) -import TyVar ( unitTyVarSet, GenTyVar ) -import Unique ( Unique ) -import Util - - --- import TcPragmas ( tcGenPragmas, tcClassOpPragmas ) -tcGenPragmas ty id ps = returnNF_Tc noIdInfo -tcClassOpPragmas ty sel def spec ps = returnNF_Tc (noIdInfo `addSpecInfo` spec, - noIdInfo) +import TcBinds ( tcBindWithSigs, tcSpecSigs ) +import TcMonoType ( tcHsSigType, tcClassContext, checkSigTyVars, sigCtxt, mkTcSig ) +import TcSimplify ( tcSimplifyAndCheck, bindInstsOfLocalFuns ) +import TcType ( TcType, TcTyVar, tcInstTyVars, zonkTcSigTyVars ) +import TcMonad +import PrelInfo ( nO_METHOD_BINDING_ERROR_ID ) +import Bag ( bagToList ) +import Class ( classTyVars, classBigSig, classSelIds, classTyCon, Class, ClassOpItem ) +import CmdLineOpts ( opt_GlasgowExts, opt_WarnMissingMethods ) +import MkId ( mkDictSelId, mkDataConId, mkDataConWrapId, mkDefaultMethodId ) +import DataCon ( mkDataCon, notMarkedStrict ) +import Id ( Id, idType, idName ) +import Name ( Name, nameOccName, isLocallyDefined, NamedThing(..) ) +import NameSet ( NameSet, mkNameSet, elemNameSet, emptyNameSet ) +import Outputable +import Type ( Type, ClassContext, mkTyVarTys, mkDictTys, mkSigmaTy, mkClassPred ) +import Var ( TyVar ) +import VarSet ( mkVarSet, emptyVarSet ) +import Maybes ( seqMaybe ) \end{code} @@ -98,143 +83,136 @@ Now DictTy in Type is just a form of type synomym: Death to "ExpandingDicts". +%************************************************************************ +%* * +\subsection{Type checking} +%* * +%************************************************************************ + \begin{code} -tcClassDecl1 rec_inst_mapper +tcClassDecl1 :: ValueEnv -> RenamedTyClDecl -> TcM s (Name, TyThingDetails) +tcClassDecl1 rec_env (ClassDecl context class_name - tyvar_name class_sigs def_methods pragmas src_loc) - = tcAddSrcLoc src_loc $ - tcAddErrCtxt (classDeclCtxt class_name) $ + 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_` -- LOOK THINGS UP IN THE ENVIRONMENT - tcLookupClass class_name `thenTc` \ (class_kind, rec_class) -> - tcLookupTyVar (getTyVarName tyvar_name) `thenNF_Tc` \ (tyvar_kind, rec_tyvar) -> + tcLookupTy class_name `thenTc` \ (AClass clas) -> let - (rec_class_inst_env, rec_class_op_inst_fn) = rec_inst_mapper rec_class + tyvars = classTyVars clas + dm_bndrs_w_locs = bagToList (collectMonoBinders def_methods) + dm_bndr_set = mkNameSet (map fst dm_bndrs_w_locs) in - - -- FORCE THE CLASS AND ITS TYVAR TO HAVE SAME KIND - unifyKind class_kind tyvar_kind `thenTc_` - + tcExtendTyVarEnv tyvars $ + -- CHECK THE CONTEXT - tcClassContext rec_class rec_tyvar context pragmas - `thenTc` \ (scs, sc_sel_ids) -> + tcSuperClasses class_name clas + context sc_sel_names `thenTc` \ (sc_theta, sc_sel_ids) -> -- CHECK THE CLASS SIGNATURES, - mapTc (tcClassSig rec_class rec_tyvar rec_class_op_inst_fn) class_sigs - `thenTc` \ sig_stuff -> + mapTc (tcClassSig rec_env dm_bndr_set clas tyvars) + (filter isClassOpSig class_sigs) `thenTc` \ sig_stuff -> - -- MAKE THE CLASS OBJECT ITSELF + -- MAKE THE CLASS DETAILS let - (ops, op_sel_ids, defm_ids) = unzip3 sig_stuff - clas = mkClass (uniqueOf class_name) (getName class_name) rec_tyvar - scs sc_sel_ids ops op_sel_ids defm_ids - rec_class_inst_env - in - returnTc clas -\end{code} - + (op_tys, op_items) = unzip sig_stuff + sc_tys = mkDictTys sc_theta + dict_component_tys = sc_tys ++ op_tys - let - clas_ty = mkTyVarTy clas_tyvar - dict_component_tys = [mkDictTy sc clas_ty | sc <- scs] ++ - [classOpLocalType op | op <- ops]) - new_or_data = case dict_component_tys of - [_] -> NewType - other -> DataType - - dict_con_id = mkDataCon class_name - [NotMarkedStrict] + dict_con = mkDataCon datacon_name + [notMarkedStrict | _ <- dict_component_tys] [{- No labelled fields -}] - [clas_tyvar] + tyvars [{-No context-}] + [{-No existential tyvars-}] [{-Or context-}] dict_component_tys - tycon - - tycon = mkDataTyCon class_name - (tyVarKind rec_tyvar `mkArrowKind` mkBoxedTypeKind) - [rec_tyvar] - [{- Empty context -}] - [dict_con_id] - [{- No derived classes -}] - new_or_data - in + (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 (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 ([Class], -- the superclasses - [Id]) -- superclass selector Ids + -> [Name] -- Names for superclass selectors + -> TcM s (ClassContext, -- the superclass context + [Id]) -- superclass selector Ids -tcClassContext rec_class rec_tyvar 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` \ theta -> - let - super_classes = [ supers | (supers, _) <- theta ] - in - -- Make super-class selector ids - mapTc (mk_super_id rec_class) super_classes `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 (super_classes, sc_sel_ids) + returnTc (sc_theta, sc_sel_ids) where - rec_tyvar_ty = mkTyVarTy rec_tyvar + check_constraint sc@(HsPClass c tys) + = checkTc (all is_tyvar tys) (superClassErr class_name sc) - mk_super_id rec_class super_class - = tcGetUnique `thenNF_Tc` \ uniq -> - let - ty = mkForAllTy rec_tyvar $ - mkFunTy (mkDictTy rec_class rec_tyvar_ty) - (mkDictTy super_class rec_tyvar_ty) - in - returnTc (mkSuperDictSelId uniq rec_class super_class ty) + is_tyvar (HsTyVar _) = True + is_tyvar other = False -tcClassSig :: Class -- Knot tying only! - -> TyVar -- The class type variable, used for error check only - -> (ClassOp -> SpecEnv) -- Ditto; the spec info for the class ops +tcClassSig :: ValueEnv -- Knot tying only! + -> NameSet -- Names bound in the default-method bindings + -> Class -- ...ditto... + -> [TyVar] -- The class type variable, used for error check only -> RenamedClassOpSig - -> TcM s (ClassOp, -- class op - Id, -- selector id - Id) -- default-method ids - -tcClassSig rec_clas rec_clas_tyvar rec_classop_spec_fn - (ClassOpSig op_name - op_ty - pragmas src_loc) + -> TcM s (Type, -- Type of the method + ClassOpItem) -- Selector Id, default-method Id, True if explicit default binding + + +tcClassSig rec_env dm_bind_names clas clas_tyvars + (ClassOpSig op_name maybe_dm_stuff op_ty src_loc) = tcAddSrcLoc src_loc $ - fixTc ( \ ~(_, rec_sel_id, rec_defm_id) -> -- Knot for pragmas -- Check the type signature. NB that the envt *already has* -- bindings for the type variables; see comments in TcTyAndClassDcls. -- 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_tyvar] - [(rec_clas, mkTyVarTy rec_clas_tyvar)] + global_ty = mkSigmaTy clas_tyvars + [mkClassPred clas (mkTyVarTys clas_tyvars)] local_ty - class_op_nm = getOccName op_name - class_op = mkClassOp class_op_nm - (classOpTagByOccName rec_clas{-yeeps!-} class_op_nm) - local_ty - in -- Build the selector id and default method id - tcGetUnique `thenNF_Tc` \ d_uniq -> - let - sel_id = mkMethodSelId op_name rec_clas class_op global_ty - defm_id = mkDefaultMethodId op_name d_uniq rec_clas class_op False global_ty - -- ToDo: improve the "False" + sel_id = mkDictSelId op_name clas in - returnTc (class_op, sel_id, defm_id) - ) + (case maybe_dm_stuff of + Nothing -> -- Source-file class declaration + newDefaultMethodName op_name src_loc `thenNF_Tc` \ dm_name -> + returnNF_Tc (mkDefaultMethodId dm_name clas global_ty, op_name `elemNameSet` dm_bind_names) + + Just (dm_name, explicit_dm) -> -- Interface-file class decl + let + dm_id = mkDefaultMethodId dm_name clas global_ty + in + returnNF_Tc (tcAddImportedIdInfo rec_env dm_id, explicit_dm) + ) `thenNF_Tc` \ (dm_id, explicit_dm) -> + + returnTc (local_ty, (sel_id, dm_id, explicit_dm)) \end{code} @@ -262,54 +240,53 @@ each local class decl. \begin{code} tcClassDecls2 :: [RenamedHsDecl] - -> NF_TcM s (LIE s, TcHsBinds s) + -> NF_TcM s (LIE, TcMonoBinds) tcClassDecls2 decls = foldr combine - (returnNF_Tc (emptyLIE, EmptyBinds)) - [tcClassDecl2 cls_decl | ClD cls_decl <- decls] + (returnNF_Tc (emptyLIE, EmptyMonoBinds)) + [tcClassDecl2 cls_decl | TyClD cls_decl <- decls, isClassDecl cls_decl] where combine tc1 tc2 = tc1 `thenNF_Tc` \ (lie1, binds1) -> tc2 `thenNF_Tc` \ (lie2, binds2) -> returnNF_Tc (lie1 `plusLIE` lie2, - binds1 `ThenBinds` binds2) + binds1 `AndMonoBinds` binds2) \end{code} @tcClassDecl2@ is the business end of things. \begin{code} -tcClassDecl2 :: RenamedClassDecl -- The class declaration - -> NF_TcM s (LIE s, TcHsBinds s) +tcClassDecl2 :: RenamedTyClDecl -- The class declaration + -> NF_TcM s (LIE, TcMonoBinds) tcClassDecl2 (ClassDecl context class_name - tyvar_name class_sigs default_binds pragmas src_loc) + tyvar_names _ class_sigs default_binds pragmas _ _ _ _ src_loc) | not (isLocallyDefined class_name) - = returnNF_Tc (emptyLIE, EmptyBinds) + = returnNF_Tc (emptyLIE, EmptyMonoBinds) | otherwise -- It is locally defined - = recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyBinds)) $ - tcAddSrcLoc src_loc $ - - -- Get the relevant class - tcLookupClass class_name `thenTc` \ (_, clas) -> - let - (tyvar, scs, sc_sel_ids, ops, op_sel_ids, defm_ids) - = classBigSig clas + = recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $ + tcAddSrcLoc src_loc $ + tcLookupTy class_name `thenNF_Tc` \ (AClass clas) -> + tcDefaultMethodBinds clas default_binds class_sigs +\end{code} +\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 = SingleBind $ NonRecBind $ foldr AndMonoBinds EmptyMonoBinds $ - [ CoreMonoBind (RealId sel_id) (getUnfoldingTemplate (getIdUnfolding sel_id)) - | sel_id <- sc_sel_ids ++ op_sel_ids, - isLocallyDefined sel_id - ] - in - -- Generate bindings for the default methods - tcInstSigTyVars [tyvar] `thenNF_Tc` \ ([clas_tyvar], _, _) -> - buildDefaultMethodBinds clas clas_tyvar defm_ids default_binds - `thenTc` \ (const_insts, meth_binds) -> + -- We don't return the data constructor etc from the class, + -- because that's done via the class's TyCon + where + (cls_ids_s, binds_s) = unzip (map mk_implicit classes) - returnTc (const_insts, sel_binds `ThenBinds` meth_binds) + mk_implicit clas = (sel_ids, binds) + where + sel_ids = classSelIds clas + binds | isLocallyDefined clas = idsToMonoBinds sel_ids + | otherwise = EmptyMonoBinds \end{code} %************************************************************************ @@ -334,23 +311,11 @@ 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} @@ -386,85 +351,237 @@ dfun.Foo.List \end{verbatim} \begin{code} -buildDefaultMethodBinds +tcDefaultMethodBinds :: Class - -> TcTyVar s - -> [Id] -> RenamedMonoBinds - -> TcM s (LIE s, TcHsBinds s) + -> [RenamedSig] + -> TcM s (LIE, TcMonoBinds) + +tcDefaultMethodBinds clas default_binds sigs + = -- Check that the default bindings come from this class + checkFromThisClass clas 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 -buildDefaultMethodBinds clas clas_tyvar - default_method_ids default_binds - = newDicts origin [(clas,inst_ty)] `thenNF_Tc` \ (this_dict, [this_dict_id]) -> - mapAndUnzipNF_Tc mk_method default_method_ids `thenNF_Tc` \ (insts_s, local_defm_ids) -> - let - avail_insts = this_dict `plusLIE` unionManyBags insts_s -- Insts available - clas_tyvar_set = unitTyVarSet clas_tyvar - in - tcExtendGlobalTyVars clas_tyvar_set ( - processInstBinds - clas - (makeClassDeclDefaultMethodRhs clas local_defm_ids) - avail_insts - local_defm_ids - default_binds - ) `thenTc` \ (insts_needed, default_binds') -> - - tcSimplifyAndCheck - clas_tyvar_set - avail_insts - insts_needed `thenTc` \ (const_lie, dict_binds) -> - + (tyvars, _, _, op_items) = classBigSig clas - let - defm_binds = AbsBinds - [clas_tyvar] - [this_dict_id] - (local_defm_ids `zip` map RealId default_method_ids) - dict_binds - (RecBind default_binds') - in - returnTc (const_lie, defm_binds) - where - inst_ty = mkTyVarTy clas_tyvar - mk_method defm_id = newMethod origin (RealId defm_id) [inst_ty] origin = ClassDeclOrigin + + -- 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 -> RenamedMonoBinds -> NF_TcM s () +checkFromThisClass clas mbinds + = mapNF_Tc check_from_this_class bndrs_w_locs `thenNF_Tc_` + returnNF_Tc () + where + check_from_this_class (bndr, loc) + | nameOccName bndr `elem` sel_names = returnNF_Tc () + | otherwise = tcAddSrcLoc loc $ + addErrTc (badMethodErr bndr clas) + sel_names = map getOccName (classSelIds clas) + bndrs_w_locs = bagToList (collectMonoBinders mbinds) \end{code} + -@makeClassDeclDefaultMethodRhs@ builds the default method for a -class declaration when no explicit default method is given. +@tcMethodBind@ is used to type-check both default-method and +instance-decl method declarations. We must type-check methods one at a +time, because their signatures may have different contexts and +tyvar sets. \begin{code} -makeClassDeclDefaultMethodRhs +tcMethodBind :: Class - -> [TcIdOcc s] - -> Int - -> NF_TcM s (TcExpr s) + -> 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 + 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 + + -- 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 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 + -- + -- 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 + 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} -makeClassDeclDefaultMethodRhs clas method_ids tag - = -- Return the expression - -- error ty "No default method for ..." - -- The interesting thing is that method_ty is a for-all type; - -- this is fun, although unusual in a type application! +Contexts and errors +~~~~~~~~~~~~~~~~~~~ +\begin{code} +classArityErr class_name + = ptext SLIT("Too many parameters for class") <+> quotes (ppr class_name) - returnNF_Tc (HsApp (mkHsTyApp (HsVar (RealId nO_DEFAULT_METHOD_ERROR_ID)) [tcIdType method_id]) - (HsLitOut (HsString (_PK_ error_msg)) stringTy)) +superClassErr class_name sc + = ptext SLIT("Illegal superclass constraint") <+> quotes (ppr sc) + <+> ptext SLIT("in declaration for class") <+> quotes (ppr class_name) - where - (clas_mod, clas_name) = modAndOcc clas +defltMethCtxt class_name + = ptext SLIT("When checking the default methods for class") <+> quotes (ppr class_name) - method_id = method_ids !! (tag-1) - class_op = (classOps clas) !! (tag-1) - - error_msg = _UNPK_ (nameString (getName clas)) - ++ (ppShow 80 (ppr PprForUser class_op)) --- ++ "\"" Don't know what this trailing quote is for! -\end{code} +methodCtxt sel_id + = ptext SLIT("In the definition for method") <+> quotes (ppr sel_id) +badMethodErr bndr clas + = hsep [ptext SLIT("Class"), quotes (ppr clas), + ptext SLIT("does not have a method"), quotes (ppr bndr)] -Contexts -~~~~~~~~ -\begin{code} -classDeclCtxt class_name sty - = ppCat [ppStr "In the class declaration for", ppr sty class_name] +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}