X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcClassDcl.lhs;h=08403bc52ac3c3ec6194db2756a56c789da94374;hb=95581e0c3b2d4d6edd33fdd6e135aa3917072c4c;hp=324038c7e91f2d0d2404eb7eae2f11eda76f19b0;hpb=40dfb7ac2b32f5ed38249f77c416e413b358df1c;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcClassDcl.lhs b/ghc/compiler/typecheck/TcClassDcl.lhs index 324038c..08403bc 100644 --- a/ghc/compiler/typecheck/TcClassDcl.lhs +++ b/ghc/compiler/typecheck/TcClassDcl.lhs @@ -4,57 +4,58 @@ \section[TcClassDcl]{Typechecking class declarations} \begin{code} -module TcClassDcl ( tcClassDecl1, tcClassDecls2, mkImplicitClassBinds, - tcMethodBind, badMethodErr +module TcClassDcl ( tcClassDecl1, tcClassDecls2, + tcMethodBind, mkMethodBind, badMethodErr ) where #include "HsVersions.h" -import HsSyn ( HsDecl(..), TyClDecl(..), Sig(..), MonoBinds(..), - HsExpr(..), HsLit(..), HsType(..), HsPred(..), +import HsSyn ( TyClDecl(..), Sig(..), MonoBinds(..), + HsExpr(..), HsLit(..), mkSimpleMatch, andMonoBinds, andMonoBindList, - isClassDecl, isClassOpSig, isPragSig, - fromClassDeclNameList, tyClDeclName + isClassOpSig, isPragSig, + getClassDeclSysNames, placeHolderType ) -import BasicTypes ( NewOrData(..), TopLevelFlag(..), RecFlag(..), EP(..) ) +import BasicTypes ( RecFlag(..), StrictnessMark(..) ) import RnHsSyn ( RenamedTyClDecl, RenamedClassOpSig, RenamedMonoBinds, - RenamedContext, RenamedHsDecl, RenamedSig, - RenamedHsExpr, maybeGenericMatch + maybeGenericMatch ) -import TcHsSyn ( TcMonoBinds, idsToMonoBinds ) +import TcHsSyn ( TcMonoBinds ) -import Inst ( InstOrigin(..), LIE, emptyLIE, plusLIE, plusLIEs, newDicts, newMethod ) -import TcEnv ( TcId, ValueEnv, TyThing(..), TyThingDetails(..), tcAddImportedIdInfo, - tcLookupClass, tcExtendTyVarEnvForMeths, tcExtendGlobalTyVars, - tcExtendLocalValEnv, tcExtendTyVarEnv, newDefaultMethodName +import Inst ( Inst, InstOrigin(..), LIE, emptyLIE, plusLIE, plusLIEs, + instToId, newDicts, newMethod ) +import TcEnv ( TyThingDetails(..), + tcLookupClass, tcExtendTyVarEnv2, + tcExtendTyVarEnv + ) +import TcBinds ( tcMonoBinds ) +import TcMonoType ( TcSigInfo(..), tcHsType, tcHsTheta, mkTcSig ) +import TcSimplify ( tcSimplifyCheck ) +import TcUnify ( checkSigTyVars, sigCtxt ) +import TcMType ( tcInstTyVars, checkValidTheta, checkValidType, SourceTyCtxt(..), UserTypeCtxt(..) ) +import TcType ( Type, TyVarDetails(..), TcType, TcThetaType, TcTyVar, + mkTyVarTys, mkPredTys, mkClassPred, + tcIsTyVarTy, tcSplitTyConApp_maybe, tcSplitSigmaTy ) -import TcBinds ( tcBindWithSigs, tcSpecSigs ) -import TcMonoType ( tcHsSigType, tcClassContext, checkSigTyVars, sigCtxt, mkTcSig ) -import TcSimplify ( tcSimplifyAndCheck, bindInstsOfLocalFuns ) -import TcType ( TcType, TcTyVar, tcInstTyVars, zonkTcSigTyVars ) import TcMonad -import Generics ( mkGenericRhs, validGenericMethodType ) +import Generics ( mkGenericRhs ) import PrelInfo ( nO_METHOD_BINDING_ERROR_ID ) -import Class ( classTyVars, classBigSig, classSelIds, classTyCon, Class, ClassOpItem, - DefMeth (..) ) -import Bag ( bagToList ) -import CmdLineOpts ( opt_GlasgowExts, opt_WarnMissingMethods, opt_PprStyle_Debug ) +import Class ( classTyVars, classBigSig, classTyCon, className, + Class, ClassOpItem, DefMeth (..) ) import MkId ( mkDictSelId, mkDataConId, mkDataConWrapId, mkDefaultMethodId ) -import DataCon ( mkDataCon, notMarkedStrict ) -import Id ( Id, idType, idName ) -import Name ( Name, nameOccName, isLocallyDefined, NamedThing(..), mkSysLocalName, - NameEnv, lookupNameEnv, emptyNameEnv, unitNameEnv, plusNameEnv, nameEnvElts ) -import NameSet ( NameSet, mkNameSet, elemNameSet, emptyNameSet ) +import DataCon ( mkDataCon ) +import Id ( Id, idType, idName, setIdLocalExported ) +import Module ( Module ) +import Name ( Name, NamedThing(..) ) +import NameEnv ( NameEnv, lookupNameEnv, emptyNameEnv, unitNameEnv, plusNameEnv ) +import NameSet ( emptyNameSet ) import Outputable -import Type ( Type, ClassContext, mkTyVarTys, mkDictTys, mkSigmaTy, mkClassPred, - splitTyConApp_maybe, isTyVarTy - ) import Var ( TyVar ) -import VarSet ( mkVarSet, emptyVarSet ) +import CmdLineOpts import ErrUtils ( dumpIfSet ) -import Util ( count ) -import Maybes ( seqMaybe, maybeToBool, orElse ) +import Util ( count, isSingleton, lengthIs, equalLength ) +import Maybes ( seqMaybe, maybeToBool ) \end{code} @@ -99,43 +100,43 @@ Death to "ExpandingDicts". %************************************************************************ \begin{code} -tcClassDecl1 :: ValueEnv -> RenamedTyClDecl -> TcM (Name, TyThingDetails) -tcClassDecl1 rec_env - (ClassDecl context class_name - tyvar_names fundeps class_sigs def_methods pragmas - sys_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 + +tcClassDecl1 :: RenamedTyClDecl -> TcM (Name, TyThingDetails) +tcClassDecl1 (ClassDecl {tcdCtxt = context, tcdName = class_name, + tcdTyVars = tyvar_names, tcdFDs = fundeps, + tcdSigs = class_sigs, tcdMeths = def_methods, + tcdSysNames = sys_names, tcdLoc = src_loc}) + = -- LOOK THINGS UP IN THE ENVIRONMENT tcLookupClass class_name `thenTc` \ clas -> let tyvars = classTyVars clas op_sigs = filter isClassOpSig class_sigs op_names = [n | ClassOpSig n _ _ _ <- op_sigs] - (_, datacon_name, datacon_wkr_name, sc_sel_names) = fromClassDeclNameList sys_names + (_, datacon_name, datacon_wkr_name, sc_sel_names) = getClassDeclSysNames sys_names in tcExtendTyVarEnv tyvars $ - -- CHECK THAT THE DEFAULT BINDINGS ARE LEGAL - checkDefaultBinds clas op_names def_methods `thenTc` \ dm_info -> - checkGenericClassIsUnary clas dm_info `thenTc_` + checkDefaultBinds clas op_names def_methods `thenTc` \ mb_dm_env -> -- CHECK THE CONTEXT - tcSuperClasses clas context sc_sel_names `thenTc` \ (sc_theta, sc_sel_ids) -> + -- The renamer has already checked that the context mentions + -- only the type variable of the class decl. + -- Context is already kind-checked + ASSERT( equalLength context sc_sel_names ) + tcHsTheta context `thenTc` \ sc_theta -> -- CHECK THE CLASS SIGNATURES, - mapTc (tcClassSig rec_env clas tyvars dm_info) op_sigs `thenTc` \ sig_stuff -> + mapTc (tcClassSig clas tyvars mb_dm_env) op_sigs `thenTc` \ sig_stuff -> -- MAKE THE CLASS DETAILS let (op_tys, op_items) = unzip sig_stuff - sc_tys = mkDictTys sc_theta + sc_tys = mkPredTys sc_theta dict_component_tys = sc_tys ++ op_tys + sc_sel_ids = [mkDictSelId sc_name clas | sc_name <- sc_sel_names] dict_con = mkDataCon datacon_name - [notMarkedStrict | _ <- dict_component_tys] + [NotMarkedStrict | _ <- dict_component_tys] [{- No labelled fields -}] tyvars [{-No context-}] @@ -151,91 +152,56 @@ tcClassDecl1 rec_env \end{code} \begin{code} -checkDefaultBinds :: Class -> [Name] -> RenamedMonoBinds -> TcM (NameEnv (DefMeth Name)) +checkDefaultBinds :: Class -> [Name] -> Maybe RenamedMonoBinds + -> TcM (Maybe (NameEnv Bool)) + -- The returned environment says + -- x not in env => no default method + -- x -> True => generic default method + -- x -> False => polymorphic default method + -- Check default bindings -- a) must be for a class op for this class -- b) must be all generic or all non-generic -- and return a mapping from class-op to DefMeth info -checkDefaultBinds clas ops EmptyMonoBinds = returnTc emptyNameEnv + -- But do all this only for source binds -checkDefaultBinds clas ops (AndMonoBinds b1 b2) - = checkDefaultBinds clas ops b1 `thenTc` \ dm_info1 -> - checkDefaultBinds clas ops b2 `thenTc` \ dm_info2 -> - returnTc (dm_info1 `plusNameEnv` dm_info2) +checkDefaultBinds clas ops Nothing + = returnTc Nothing -checkDefaultBinds clas ops (FunMonoBind op _ matches loc) - = tcAddSrcLoc loc $ +checkDefaultBinds clas ops (Just mbs) + = go mbs `thenTc` \ dm_env -> + returnTc (Just dm_env) + where + go EmptyMonoBinds = returnTc emptyNameEnv + + go (AndMonoBinds b1 b2) + = go b1 `thenTc` \ dm_info1 -> + go b2 `thenTc` \ dm_info2 -> + returnTc (dm_info1 `plusNameEnv` dm_info2) + + go (FunMonoBind op _ matches loc) + = tcAddSrcLoc loc $ -- Check that the op is from this class - checkTc (op `elem` ops) (badMethodErr clas op) `thenTc_` + checkTc (op `elem` ops) (badMethodErr clas op) `thenTc_` -- Check that all the defns ar generic, or none are - checkTc (all_generic || none_generic) (mixedGenericErr op) `thenTc_` + checkTc (all_generic || none_generic) (mixedGenericErr op) `thenTc_` - -- Make up the right dm_info - if all_generic then - returnTc (unitNameEnv op GenDefMeth) - else - -- An explicit non-generic default method - newDefaultMethodName op loc `thenNF_Tc` \ dm_name -> - returnTc (unitNameEnv op (DefMeth dm_name)) - - where - n_generic = count (maybeToBool . maybeGenericMatch) matches - none_generic = n_generic == 0 - all_generic = n_generic == length matches - -checkGenericClassIsUnary clas dm_info - = -- Check that if the class has generic methods, then the - -- class has only one parameter. We can't do generic - -- multi-parameter type classes! - checkTc (unary || no_generics) (genericMultiParamErr clas) - where - unary = length (classTyVars clas) == 1 - no_generics = null [() | GenDefMeth <- nameEnvElts dm_info] + returnTc (unitNameEnv op all_generic) + where + n_generic = count (maybeToBool . maybeGenericMatch) matches + none_generic = n_generic == 0 + all_generic = matches `lengthIs` n_generic \end{code} \begin{code} -tcSuperClasses :: Class - -> RenamedContext -- class context - -> [Name] -- Names for superclass selectors - -> TcM (ClassContext, -- the superclass context - [Id]) -- superclass selector Ids - -tcSuperClasses 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. - - -- 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_sel_ids) - - where - check_constraint sc@(HsPClass c tys) - = checkTc (all is_tyvar tys) (superClassErr clas sc) - - is_tyvar (HsTyVar _) = True - is_tyvar other = False - - -tcClassSig :: ValueEnv -- Knot tying only! - -> Class -- ...ditto... +tcClassSig :: Class -- ...ditto... -> [TyVar] -- The class type variable, used for error check only - -> NameEnv (DefMeth Name) -- Info about default methods + -> Maybe (NameEnv Bool) -- Info about default methods; + -- Nothing => imported class defn with no method binds -> RenamedClassOpSig -> TcM (Type, -- Type of the method ClassOpItem) -- Selector Id, default-method Id, True if explicit default binding @@ -245,72 +211,36 @@ tcClassSig :: ValueEnv -- Knot tying only! -- so we distinguish them in checkDefaultBinds, and pass this knowledge in the -- Class.DefMeth data structure. -tcClassSig rec_env clas clas_tyvars dm_info - (ClassOpSig op_name maybe_dm op_ty src_loc) +tcClassSig clas clas_tyvars maybe_dm_env + (ClassOpSig op_name sig_dm op_ty src_loc) = tcAddSrcLoc src_loc $ -- Check the type signature. NB that the envt *already has* -- bindings for the type variables; see comments in TcTyAndClassDcls. + tcHsType op_ty `thenTc` \ local_ty -> - -- NB: Renamer checks that the class type variable is mentioned in local_ty, - -- and that it is not constrained by theta - tcHsSigType op_ty `thenTc` \ local_ty -> let - global_ty = mkSigmaTy clas_tyvars - [mkClassPred clas (mkTyVarTys clas_tyvars)] - local_ty + theta = [mkClassPred clas (mkTyVarTys clas_tyvars)] -- Build the selector id and default method id - sel_id = mkDictSelId op_name clas + sel_id = mkDictSelId op_name clas + DefMeth dm_name = sig_dm - dm_info_name = maybe_dm `orElse` lookupNameEnv dm_info op_name `orElse` NoDefMeth + dm_info = case maybe_dm_env of + Nothing -> sig_dm + Just dm_env -> mk_src_dm_info dm_env - dm_info_id = case dm_info_name of - NoDefMeth -> NoDefMeth - GenDefMeth -> GenDefMeth - DefMeth dm_name -> DefMeth (tcAddImportedIdInfo rec_env dm_id) - where - dm_id = mkDefaultMethodId dm_name clas global_ty + mk_src_dm_info dm_env = case lookupNameEnv dm_env op_name of + Nothing -> NoDefMeth + Just True -> GenDefMeth + Just False -> DefMeth dm_name in - -- Check that for a generic method, the type of - -- the method is sufficiently simple - checkTc (dm_info_name /= GenDefMeth || validGenericMethodType local_ty) - (badGenericMethodType op_name op_ty) `thenTc_` - - returnTc (local_ty, (sel_id, dm_info_id)) + returnTc (local_ty, (sel_id, dm_info)) \end{code} %************************************************************************ %* * -\subsection[ClassDcl-pass2]{Class decls pass 2: default methods} -%* * -%************************************************************************ - -@mkImplicitClassBinds@ produces a binding for the selector function for each method -and superclass dictionary. - -\begin{code} -mkImplicitClassBinds :: [Class] -> NF_TcM ([Id], TcMonoBinds) -mkImplicitClassBinds classes - = returnNF_Tc (concat cls_ids_s, andMonoBindList binds_s) - -- The selector binds are already in the selector Id's unfoldings - -- 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) - - mk_implicit clas = (sel_ids, binds) - where - sel_ids = classSelIds clas - binds | isLocallyDefined clas = idsToMonoBinds sel_ids - | otherwise = EmptyMonoBinds -\end{code} - - - -%************************************************************************ -%* * \subsection[Default methods]{Default methods} %* * %************************************************************************ @@ -374,19 +304,19 @@ The function @tcClassDecls2@ just arranges to apply @tcClassDecl2@ to each local class decl. \begin{code} -tcClassDecls2 :: [RenamedHsDecl] -> NF_TcM (LIE, TcMonoBinds) +tcClassDecls2 :: Module -> [RenamedTyClDecl] -> NF_TcM (LIE, TcMonoBinds, [Id]) -tcClassDecls2 decls +tcClassDecls2 this_mod decls = foldr combine - (returnNF_Tc (emptyLIE, EmptyMonoBinds)) - [tcClassDecl2 cls_decl | TyClD cls_decl <- decls, - isClassDecl cls_decl, - isLocallyDefined (tyClDeclName cls_decl)] + (returnNF_Tc (emptyLIE, EmptyMonoBinds, [])) + [tcClassDecl2 cls_decl | cls_decl@(ClassDecl {tcdMeths = Just _}) <- decls] + -- The 'Just' picks out source ClassDecls where - combine tc1 tc2 = tc1 `thenNF_Tc` \ (lie1, binds1) -> - tc2 `thenNF_Tc` \ (lie2, binds2) -> + combine tc1 tc2 = tc1 `thenNF_Tc` \ (lie1, binds1, ids1) -> + tc2 `thenNF_Tc` \ (lie2, binds2, ids2) -> returnNF_Tc (lie1 `plusLIE` lie2, - binds1 `AndMonoBinds` binds2) + binds1 `AndMonoBinds` binds2, + ids1 ++ ids2) \end{code} @tcClassDecl2@ generates bindings for polymorphic default methods @@ -394,12 +324,12 @@ tcClassDecls2 decls \begin{code} tcClassDecl2 :: RenamedTyClDecl -- The class declaration - -> NF_TcM (LIE, TcMonoBinds) + -> NF_TcM (LIE, TcMonoBinds, [Id]) -tcClassDecl2 (ClassDecl context class_name - tyvar_names _ sigs default_binds pragmas _ src_loc) - = -- A locally defined class - recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $ +tcClassDecl2 (ClassDecl {tcdName = class_name, tcdSigs = sigs, + tcdMeths = Just default_binds, tcdLoc = src_loc}) + = -- The 'Just' picks out source ClassDecls + recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds, [])) $ tcAddSrcLoc src_loc $ tcLookupClass class_name `thenNF_Tc` \ clas -> @@ -416,13 +346,13 @@ tcClassDecl2 (ClassDecl context class_name prags = filter isPragSig sigs tc_dm = tcDefMeth clas tyvars default_binds prags in - mapAndUnzipTc tc_dm op_items `thenTc` \ (defm_binds, const_lies) -> + mapAndUnzip3Tc tc_dm op_items `thenTc` \ (defm_binds, const_lies, dm_ids_s) -> - returnTc (plusLIEs const_lies, andMonoBindList defm_binds) + returnTc (plusLIEs const_lies, andMonoBindList defm_binds, concat dm_ids_s) -tcDefMeth clas tyvars binds_in prags (_, NoDefMeth) = returnTc (EmptyMonoBinds, emptyLIE) -tcDefMeth clas tyvars binds_in prags (_, GenDefMeth) = returnTc (EmptyMonoBinds, emptyLIE) +tcDefMeth clas tyvars binds_in prags (_, NoDefMeth) = returnTc (EmptyMonoBinds, emptyLIE, []) +tcDefMeth clas tyvars binds_in prags (_, GenDefMeth) = returnTc (EmptyMonoBinds, emptyLIE, []) -- Generate code for polymorphic default methods only -- (Generic default methods have turned into instance decls by now.) -- This is incompatible with Hugs, which expects a polymorphic @@ -430,41 +360,50 @@ tcDefMeth clas tyvars binds_in prags (_, GenDefMeth) = returnTc (EmptyMonoBinds, -- the programmer supplied an explicit default decl for the class. -- (If necessary we can fix that, but we don't have a convenient Id to hand.) -tcDefMeth clas tyvars binds_in prags op_item@(_, DefMeth dm_id) - = tcInstTyVars tyvars `thenNF_Tc` \ (clas_tyvars, inst_tys, _) -> +tcDefMeth clas tyvars binds_in prags op_item@(sel_id, DefMeth dm_name) + = tcInstTyVars ClsTv tyvars `thenNF_Tc` \ (clas_tyvars, inst_tys, _) -> let - theta = [(mkClassPred clas inst_tys)] + dm_ty = idType sel_id -- Same as dict selector! + -- The default method's type should really come from the + -- iface file, since it could be usage-generalised, but this + -- requires altering the mess of knots in TcModule and I'm + -- too scared to do that. Instead, I have disabled generalisation + -- of types of default methods (and dict funs) by annotating them + -- TyGenNever (in MkId). Ugh! KSW 1999-09. + + theta = [mkClassPred clas inst_tys] + dm_id = mkDefaultMethodId dm_name dm_ty + local_dm_id = setIdLocalExported dm_id + -- Reason for setIdLocalExported: see notes with MkId.mkDictFunId + xtve = tyvars `zip` clas_tyvars in - newDicts origin theta `thenNF_Tc` \ (this_dict, [this_dict_id]) -> + newDicts origin theta `thenNF_Tc` \ [this_dict] -> - tcExtendTyVarEnvForMeths tyvars clas_tyvars ( - tcMethodBind clas origin clas_tyvars inst_tys theta - binds_in prags False op_item - ) `thenTc` \ (defm_bind, insts_needed, (_, local_dm_id)) -> + mkMethodBind origin clas inst_tys binds_in op_item `thenTc` \ (dm_inst, meth_info) -> + tcMethodBind xtve clas_tyvars theta + [this_dict] meth_info `thenTc` \ (defm_bind, insts_needed) -> 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 + tcSimplifyCheck (ptext SLIT("class") <+> ppr clas) - (mkVarSet clas_tyvars') - this_dict + clas_tyvars + [this_dict] insts_needed `thenTc` \ (const_lie, dict_binds) -> + + -- Simplification can do unification + checkSigTyVars clas_tyvars `thenTc` \ clas_tyvars' -> let full_bind = AbsBinds clas_tyvars' - [this_dict_id] - [(clas_tyvars', dm_id, local_dm_id)] + [instToId this_dict] + [(clas_tyvars', local_dm_id, instToId dm_inst)] emptyNameSet -- No inlines (yet) (dict_binds `andMonoBinds` defm_bind) in - returnTc (full_bind, const_lie) + returnTc (full_bind, const_lie, [dm_id]) where origin = ClassDeclOrigin \end{code} @@ -484,83 +423,105 @@ tyvar sets. \begin{code} tcMethodBind - :: Class - -> InstOrigin + :: [(TyVar,TcTyVar)] -- Bindings for type environment -> [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 (TcMonoBinds, LIE, (LIE, TcId)) - -tcMethodBind clas origin inst_tyvars inst_tys inst_theta - meth_binds prags is_inst_decl (sel_id, dm_info) + -- enclosing class/instance decl. + -- They'll be signature tyvars, and we + -- want to check that they don't get bound + -- Always equal the range of the type envt + -> TcThetaType -- Available theta; it's just used for the error message + -> [Inst] -- Available from context, used to simplify constraints + -- from the method body + -> (Id, TcSigInfo, RenamedMonoBinds) -- Details of this method + -> TcM (TcMonoBinds, LIE) + +tcMethodBind xtve inst_tyvars inst_theta avail_insts + (sel_id, meth_sig, meth_bind) + = + -- Check the bindings; first adding inst_tyvars to the envt + -- so that we don't quantify over them in nested places + tcExtendTyVarEnv2 xtve ( + tcAddErrCtxt (methodCtxt sel_id) $ + tcMonoBinds meth_bind [meth_sig] NonRecursive + ) `thenTc` \ (meth_bind, meth_lie, _, _) -> + + -- Now do context reduction. We simplify wrt both the local tyvars + -- and the ones of the class/instance decl, so that there is + -- no problem with + -- class C a where + -- op :: Eq a => a -> b -> a + -- + -- We do this for each method independently to localise error messages + + let + TySigInfo meth_id meth_tvs meth_theta _ local_meth_id _ _ = meth_sig + in + tcAddErrCtxtM (sigCtxt sel_id inst_tyvars inst_theta (idType meth_id)) $ + newDicts SignatureOrigin meth_theta `thenNF_Tc` \ meth_dicts -> + let + all_tyvars = meth_tvs ++ inst_tyvars + all_insts = avail_insts ++ meth_dicts + in + tcSimplifyCheck + (ptext SLIT("class or instance method") <+> quotes (ppr sel_id)) + all_tyvars all_insts meth_lie `thenTc` \ (lie, lie_binds) -> + + checkSigTyVars all_tyvars `thenTc` \ all_tyvars' -> + + let + meth_tvs' = take (length meth_tvs) all_tyvars' + poly_meth_bind = AbsBinds meth_tvs' + (map instToId meth_dicts) + [(meth_tvs', meth_id, local_meth_id)] + emptyNameSet -- Inlines? + (lie_binds `andMonoBinds` meth_bind) + in + returnTc (poly_meth_bind, lie) + + +mkMethodBind :: InstOrigin + -> Class -> [TcType] -- Class and instance types + -> RenamedMonoBinds -- Method binding (pick the right one from in here) + -> ClassOpItem + -> TcM (Inst, -- Method inst + (Id, -- Global selector Id + TcSigInfo, -- Signature + RenamedMonoBinds)) -- Binding for the method + +mkMethodBind origin clas inst_tys meth_binds (sel_id, dm_info) = tcGetSrcLoc `thenNF_Tc` \ loc -> - newMethod origin sel_id inst_tys `thenNF_Tc` \ meth@(_, meth_id) -> - mkTcSig meth_id loc `thenNF_Tc` \ sig_info -> + newMethod origin sel_id inst_tys `thenNF_Tc` \ meth_inst -> let + meth_id = instToId meth_inst meth_name = idName meth_id - sig_msg = ptext SLIT("When checking the expected type for class method") <+> ppr sel_id - meth_prags = find_prags (idName sel_id) meth_name prags in -- Figure out what method binding to use -- If the user suppplied one, use it, else construct a default one (case find_bind (idName sel_id) meth_name meth_binds of Just user_bind -> returnTc user_bind - Nothing -> mkDefMethRhs is_inst_decl clas inst_tys sel_id loc dm_info `thenTc` \ rhs -> + Nothing -> mkDefMethRhs origin clas inst_tys sel_id loc dm_info `thenTc` \ rhs -> returnTc (FunMonoBind meth_name False -- Not infix decl - [mkSimpleMatch [] rhs Nothing loc] loc) + [mkSimpleMatch [] rhs placeHolderType loc] loc) ) `thenTc` \ meth_bind -> - -- 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 - -- ...and this is why the call to tcExtendGlobalTyVars must be here - -- rather than in the caller - 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) + + mkTcSig meth_id loc `thenNF_Tc` \ meth_sig -> + + returnTc (meth_inst, (sel_id, meth_sig, meth_bind)) + -- The user didn't supply a method binding, -- so we have to make up a default binding -- The RHS of a default method depends on the default-method info -mkDefMethRhs is_inst_decl clas inst_tys sel_id loc (DefMeth dm_id) +mkDefMethRhs origin clas inst_tys sel_id loc (DefMeth dm_name) = -- An polymorphic default method - returnTc (HsVar (idName dm_id)) + returnTc (HsVar dm_name) -mkDefMethRhs is_inst_decl clas inst_tys sel_id loc NoDefMeth +mkDefMethRhs origin clas inst_tys sel_id loc NoDefMeth = -- No default method -- Warn only if -fwarn-missing-methods - warnTc (is_inst_decl && opt_WarnMissingMethods) - (omittedMethodWarn sel_id clas) `thenNF_Tc_` + doptsTc Opt_WarnMissingMethods `thenNF_Tc` \ warn -> + warnTc (isInstDecl origin && warn) + (omittedMethodWarn sel_id) `thenNF_Tc_` returnTc error_rhs where error_rhs = HsApp (HsVar (getName nO_METHOD_BINDING_ERROR_ID)) @@ -568,15 +529,15 @@ mkDefMethRhs is_inst_decl clas inst_tys sel_id loc NoDefMeth error_msg = showSDoc (hcat [ppr loc, text "|", ppr sel_id ]) -mkDefMethRhs is_inst_decl clas inst_tys sel_id loc GenDefMeth +mkDefMethRhs origin clas inst_tys sel_id loc GenDefMeth = -- A generic default method -- If the method is defined generically, we can only do the job if the -- instance declaration is for a single-parameter type class with -- a type constructor applied to type arguments in the instance decl -- (checkTc, so False provokes the error) - checkTc (not is_inst_decl || simple_inst) - (badGenericInstance sel_id clas) `thenTc_` - + checkTc (not (isInstDecl origin) || simple_inst) + (badGenericInstance sel_id) `thenTc_` + ioToTc (dumpIfSet opt_PprStyle_Debug "Generic RHS" stuff) `thenNF_Tc_` returnTc rhs where @@ -593,10 +554,13 @@ mkDefMethRhs is_inst_decl clas inst_tys sel_id loc GenDefMeth clas_tyvar = head (classTyVars clas) Just tycon = maybe_tycon maybe_tycon = case inst_tys of - [ty] -> case splitTyConApp_maybe ty of - Just (tycon, arg_tys) | all isTyVarTy arg_tys -> Just tycon - other -> Nothing + [ty] -> case tcSplitTyConApp_maybe ty of + Just (tycon, arg_tys) | all tcIsTyVarTy arg_tys -> Just tycon + other -> Nothing other -> Nothing + +isInstDecl InstanceDeclOrigin = True +isInstDecl ClassDeclOrigin = False \end{code} @@ -614,10 +578,8 @@ find_bind sel_name meth_name other = Nothing -- Default case find_prags sel_name meth_name [] = [] find_prags sel_name meth_name (SpecSig name ty loc : prags) | name == sel_name = SpecSig meth_name ty loc : find_prags sel_name meth_name prags -find_prags sel_name meth_name (InlineSig name phase loc : prags) - | name == sel_name = InlineSig meth_name phase loc : find_prags sel_name meth_name prags -find_prags sel_name meth_name (NoInlineSig name phase loc : prags) - | name == sel_name = NoInlineSig meth_name phase loc : find_prags sel_name meth_name prags +find_prags sel_name meth_name (InlineSig sense name phase loc : prags) + | name == sel_name = InlineSig sense meth_name phase loc : find_prags sel_name meth_name prags find_prags sel_name meth_name (prag:prags) = find_prags sel_name meth_name prags \end{code} @@ -625,13 +587,6 @@ find_prags sel_name meth_name (prag:prags) = find_prags sel_name meth_name prags Contexts and errors ~~~~~~~~~~~~~~~~~~~ \begin{code} -classArityErr class_name - = ptext SLIT("Too many parameters for class") <+> quotes (ppr class_name) - -superClassErr clas sc - = ptext SLIT("Illegal superclass constraint") <+> quotes (ppr sc) - <+> ptext SLIT("in declaration for class") <+> quotes (ppr clas) - defltMethCtxt clas = ptext SLIT("When checking the default methods for class") <+> quotes (ppr clas) @@ -642,25 +597,14 @@ badMethodErr clas op = hsep [ptext SLIT("Class"), quotes (ppr clas), ptext SLIT("does not have a method"), quotes (ppr op)] -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)] - -badGenericMethodType op op_ty - = hang (ptext SLIT("Generic method type is too complex")) - 4 (vcat [ppr op <+> dcolon <+> ppr op_ty, - ptext SLIT("You can only use type variables, arrows, and tuples")]) +omittedMethodWarn sel_id + = ptext SLIT("No explicit method nor default method for") <+> quotes (ppr sel_id) -badGenericInstance sel_id clas +badGenericInstance sel_id = sep [ptext SLIT("Can't derive generic code for") <+> quotes (ppr sel_id), ptext SLIT("because the instance declaration is not for a simple type (T a b c)"), - ptext SLIT("(where T is a derivable type constructor)"), - ptext SLIT("in an instance declaration for") <+> quotes (ppr clas)] + ptext SLIT("(where T is a derivable type constructor)")] mixedGenericErr op = ptext SLIT("Can't mix generic and non-generic equations for class method") <+> quotes (ppr op) - -genericMultiParamErr clas - = ptext SLIT("The multi-parameter class") <+> quotes (ppr clas) <+> - ptext SLIT("cannot have generic methods") \end{code}