X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcClassDcl.lhs;h=820ed749f5a100788c6196d3a06ed98793065266;hb=abbc5a0be1df84a33015470319062ed7a3aa3153;hp=c4ede90ec5395c1d75d1fcb92810b83672328399;hpb=a9d4abde339c30eeb7c7baf0a0edb13fa4a2eacd;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcClassDcl.lhs b/ghc/compiler/typecheck/TcClassDcl.lhs index c4ede90..820ed74 100644 --- a/ghc/compiler/typecheck/TcClassDcl.lhs +++ b/ghc/compiler/typecheck/TcClassDcl.lhs @@ -4,57 +4,64 @@ \section[TcClassDcl]{Typechecking class declarations} \begin{code} -module TcClassDcl ( tcClassDecl1, tcClassDecls2, mkImplicitClassBinds, - tcMethodBind, badMethodErr +module TcClassDcl ( tcClassDecl1, tcClassDecls2, + MethodSpec, tcMethodBind, mkMethodBind, badMethodErr ) where #include "HsVersions.h" -import HsSyn ( HsDecl(..), TyClDecl(..), Sig(..), MonoBinds(..), - HsExpr(..), HsLit(..), HsType(..), HsPred(..), +import HsSyn ( TyClDecl(..), Sig(..), MonoBinds(..), + HsExpr(..), HsLit(..), Pat(WildPat), mkSimpleMatch, andMonoBinds, andMonoBindList, - isClassDecl, isClassOpSig, isPragSig, - fromClassDeclNameList, tyClDeclName + isClassOpSig, isPragSig, + placeHolderType ) -import BasicTypes ( NewOrData(..), TopLevelFlag(..), RecFlag(..), EP(..) ) -import RnHsSyn ( RenamedTyClDecl, +import BasicTypes ( RecFlag(..) ) +import RnHsSyn ( RenamedTyClDecl, RenamedSig, RenamedClassOpSig, RenamedMonoBinds, - RenamedContext, RenamedHsDecl, RenamedSig, - RenamedHsExpr, maybeGenericMatch + maybeGenericMatch ) -import TcHsSyn ( TcMonoBinds, idsToMonoBinds ) +import RnEnv ( lookupSysName ) +import TcHsSyn ( TcMonoBinds ) -import Inst ( InstOrigin(..), LIE, emptyLIE, plusLIE, plusLIEs, newDicts, newMethod ) -import TcEnv ( TcId, TcEnv, TyThing(..), TyThingDetails(..), tcAddImportedIdInfo, - tcLookupClass, tcExtendTyVarEnvForMeths, tcExtendGlobalTyVars, - tcExtendLocalValEnv, tcExtendTyVarEnv, newDefaultMethodName +import Inst ( Inst, InstOrigin(..), instToId, newDicts, newMethod ) +import TcEnv ( TyThingDetails(..), + tcLookupClass, tcExtendLocalValEnv2, + tcExtendTyVarEnv2, tcExtendTyVarEnv ) -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 TcTyDecls ( tcMkDataCon ) +import TcBinds ( tcMonoBinds, tcSpecSigs ) +import TcMonoType ( TcSigInfo(..), tcHsType, tcHsTheta, mkTcSig ) +import TcSimplify ( tcSimplifyCheck, bindInstsOfLocalFuns ) +import TcUnify ( checkSigTyVars, sigCtxt ) +import TcMType ( tcInstTyVars ) +import TcType ( Type, TyVarDetails(..), TcType, TcThetaType, TcTyVar, + mkTyVarTys, mkPredTys, mkClassPred, tcSplitSigmaTy, tcSplitFunTys, + tcIsTyVarTy, tcSplitTyConApp_maybe, tcSplitForAllTys, tcSplitPhiTy, + getClassPredTys_maybe, mkPhiTy + ) +import TcRnMonad +import Generics ( mkGenericRhs ) import PrelInfo ( nO_METHOD_BINDING_ERROR_ID ) -import Class ( classTyVars, classBigSig, classSelIds, classTyCon, Class, ClassOpItem, - DefMeth (..) ) -import Bag ( bagToList ) -import CmdLineOpts ( dopt_GlasgowExts, opt_WarnMissingMethods, opt_PprStyle_Debug ) -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 Class ( classTyVars, classBigSig, classTyCon, + Class, ClassOpItem, DefMeth (..) ) +import TyCon ( tyConGenInfo ) +import Subst ( substTyWith ) +import MkId ( mkDictSelId, mkDefaultMethodId ) +import Id ( Id, idType, idName, mkUserLocal, setInlinePragma ) +import Name ( Name, NamedThing(..) ) +import NameEnv ( NameEnv, lookupNameEnv, emptyNameEnv, unitNameEnv, plusNameEnv ) +import NameSet ( emptyNameSet, unitNameSet ) +import OccName ( mkClassTyConOcc, mkClassDataConOcc, mkSuperDictSelOcc, reportIfUnused ) import Outputable -import Type ( Type, ClassContext, mkTyVarTys, mkDictTys, mkSigmaTy, mkClassPred, - splitTyConApp_maybe, isTyVarTy - ) import Var ( TyVar ) -import VarSet ( mkVarSet, emptyVarSet ) +import CmdLineOpts +import UnicodeUtil ( stringToUtf8 ) import ErrUtils ( dumpIfSet ) -import Util ( count ) -import Maybes ( seqMaybe, maybeToBool, orElse ) +import Util ( count, lengthIs, isSingleton ) +import Maybes ( seqMaybe ) +import Maybe ( isJust ) +import FastString \end{code} @@ -99,145 +106,112 @@ Death to "ExpandingDicts". %************************************************************************ \begin{code} -tcClassDecl1 :: TcEnv -> 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 - doptsTc dopt_GlasgowExts `thenTc` \ glaExts -> - checkTc (glaExts || length tyvar_names == 1) - (classArityErr class_name) `thenTc_` - - -- LOOK THINGS UP IN THE ENVIRONMENT - tcLookupClass class_name `thenTc` \ clas -> + +tcClassDecl1 :: RenamedTyClDecl -> TcM (Name, TyThingDetails) +tcClassDecl1 (ClassDecl {tcdCtxt = context, tcdName = class_name, + tcdTyVars = tyvar_names, tcdFDs = fundeps, + tcdSigs = class_sigs, tcdMeths = def_methods, + tcdLoc = src_loc}) + = -- LOOK THINGS UP IN THE ENVIRONMENT + tcLookupClass class_name `thenM` \ 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 + tyvars = classTyVars clas + op_sigs = filter isClassOpSig class_sigs + op_names = [n | ClassOpSig n _ _ _ <- op_sigs] 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 `thenM` \ 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 + tcHsTheta context `thenM` \ sc_theta -> -- CHECK THE CLASS SIGNATURES, - mapTc (tcClassSig rec_env clas tyvars dm_info) op_sigs `thenTc` \ sig_stuff -> + mappM (tcClassSig clas tyvars mb_dm_env) op_sigs `thenM` \ sig_stuff -> -- MAKE THE CLASS DETAILS + lookupSysName class_name mkClassTyConOcc `thenM` \ tycon_name -> + lookupSysName class_name mkClassDataConOcc `thenM` \ datacon_name -> + mapM (lookupSysName class_name . mkSuperDictSelOcc) + [1..length context] `thenM` \ sc_sel_names -> + -- We number off the superclass selectors, 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!) 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 - - dict_con = mkDataCon datacon_name - [notMarkedStrict | _ <- dict_component_tys] - [{- No labelled fields -}] - tyvars - [{-No context-}] - [{-No existential tyvars-}] [{-Or context-}] - dict_component_tys - (classTyCon clas) - dict_con_id dict_wrap_id - - dict_con_id = mkDataConId datacon_wkr_name dict_con - dict_wrap_id = mkDataConWrapId dict_con + sc_sel_ids = [mkDictSelId sc_name clas | sc_name <- sc_sel_names] in - returnTc (class_name, ClassDetails sc_theta sc_sel_ids op_items dict_con) + tcMkDataCon datacon_name + [{- No strictness -}] + [{- No labelled fields -}] + tyvars [{-No context-}] + [{-No existential tyvars-}] [{-Or context-}] + dict_component_tys + (classTyCon clas) `thenM` \ dict_con -> + + returnM (class_name, ClassDetails sc_theta sc_sel_ids op_items dict_con tycon_name) \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 + = returnM Nothing -checkDefaultBinds clas ops (FunMonoBind op _ matches loc) - = tcAddSrcLoc loc $ +checkDefaultBinds clas ops (Just mbs) + = go mbs `thenM` \ dm_env -> + returnM (Just dm_env) + where + go EmptyMonoBinds = returnM emptyNameEnv + + go (AndMonoBinds b1 b2) + = go b1 `thenM` \ dm_info1 -> + go b2 `thenM` \ dm_info2 -> + returnM (dm_info1 `plusNameEnv` dm_info2) + + go (FunMonoBind op _ matches loc) + = addSrcLoc loc $ -- Check that the op is from this class - checkTc (op `elem` ops) (badMethodErr clas op) `thenTc_` + checkTc (op `elem` ops) (badMethodErr clas op) `thenM_` -- 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) `thenM_` - -- 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] + returnM (unitNameEnv op all_generic) + where + n_generic = count (isJust . 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 - doptsTc dopt_GlasgowExts `thenTc` \ glaExts -> - (if glaExts 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 :: TcEnv -- 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 @@ -247,70 +221,34 @@ tcClassSig :: TcEnv -- 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) - = tcAddSrcLoc src_loc $ +tcClassSig clas clas_tyvars maybe_dm_env + (ClassOpSig op_name sig_dm op_ty src_loc) + = addSrcLoc src_loc $ -- Check the type signature. NB that the envt *already has* -- bindings for the type variables; see comments in TcTyAndClassDcls. + tcHsType op_ty `thenM` \ 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)) -\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 + returnM (local_ty, (sel_id, dm_info)) \end{code} - %************************************************************************ %* * \subsection[Default methods]{Default methods} @@ -376,19 +314,18 @@ The function @tcClassDecls2@ just arranges to apply @tcClassDecl2@ to each local class decl. \begin{code} -tcClassDecls2 :: [RenamedHsDecl] -> NF_TcM (LIE, TcMonoBinds) +tcClassDecls2 :: [RenamedTyClDecl] -> TcM (TcMonoBinds, [Id]) tcClassDecls2 decls = foldr combine - (returnNF_Tc (emptyLIE, EmptyMonoBinds)) - [tcClassDecl2 cls_decl | TyClD cls_decl <- decls, - isClassDecl cls_decl, - isLocallyDefined (tyClDeclName cls_decl)] + (returnM (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) -> - returnNF_Tc (lie1 `plusLIE` lie2, - binds1 `AndMonoBinds` binds2) + combine tc1 tc2 = tc1 `thenM` \ (binds1, ids1) -> + tc2 `thenM` \ (binds2, ids2) -> + returnM (binds1 `AndMonoBinds` binds2, + ids1 ++ ids2) \end{code} @tcClassDecl2@ generates bindings for polymorphic default methods @@ -396,14 +333,14 @@ tcClassDecls2 decls \begin{code} tcClassDecl2 :: RenamedTyClDecl -- The class declaration - -> NF_TcM (LIE, TcMonoBinds) + -> TcM (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)) $ - tcAddSrcLoc src_loc $ - tcLookupClass class_name `thenNF_Tc` \ clas -> +tcClassDecl2 (ClassDecl {tcdName = class_name, tcdSigs = sigs, + tcdMeths = Just default_binds, tcdLoc = src_loc}) + = -- The 'Just' picks out source ClassDecls + recoverM (returnM (EmptyMonoBinds, [])) $ + addSrcLoc src_loc $ + tcLookupClass class_name `thenM` \ clas -> -- We make a separate binding for each default method. -- At one time I used a single AbsBinds for all of them, thus @@ -418,13 +355,13 @@ 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) -> + mapAndUnzipM tc_dm op_items `thenM` \ (defm_binds, dm_ids_s) -> - returnTc (plusLIEs const_lies, andMonoBindList defm_binds) + returnM (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) = returnM (EmptyMonoBinds, []) +tcDefMeth clas tyvars binds_in prags (_, GenDefMeth) = returnM (EmptyMonoBinds, []) -- 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 @@ -432,41 +369,42 @@ 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 `thenM` \ (clas_tyvars, inst_tys, _) -> let - theta = [(mkClassPred clas inst_tys)] + dm_ty = idType sel_id -- Same as dict selector! + theta = [mkClassPred clas inst_tys] + local_dm_id = mkDefaultMethodId dm_name dm_ty + xtve = tyvars `zip` clas_tyvars in - newDicts origin theta `thenNF_Tc` \ (this_dict, [this_dict_id]) -> + newDicts origin theta `thenM` \ [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 `thenM` \ (_, meth_info) -> + getLIE (tcMethodBind xtve clas_tyvars theta + [this_dict] prags meth_info) `thenM` \ (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' -> + addErrCtxt (defltMethCtxt clas) $ -- Check the context - tcSimplifyAndCheck + tcSimplifyCheck (ptext SLIT("class") <+> ppr clas) - (mkVarSet clas_tyvars') - this_dict - insts_needed `thenTc` \ (const_lie, dict_binds) -> + clas_tyvars + [this_dict] + insts_needed `thenM` \ dict_binds -> + + -- Simplification can do unification + checkSigTyVars clas_tyvars `thenM` \ clas_tyvars' -> let + (_,dm_inst_id,_) = meth_info full_bind = AbsBinds clas_tyvars' - [this_dict_id] - [(clas_tyvars', dm_id, local_dm_id)] + [instToId this_dict] + [(clas_tyvars', local_dm_id, dm_inst_id)] emptyNameSet -- No inlines (yet) (dict_binds `andMonoBinds` defm_bind) in - returnTc (full_bind, const_lie) + returnM (full_bind, [local_dm_id]) where origin = ClassDeclOrigin \end{code} @@ -485,102 +423,224 @@ time, because their signatures may have different contexts and tyvar sets. \begin{code} +type MethodSpec = (Id, -- Global selector Id + Id, -- Local Id (class tyvars instantiated) + RenamedMonoBinds) -- Binding for the method + 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) - = tcGetSrcLoc `thenNF_Tc` \ loc -> - newMethod origin sel_id inst_tys `thenNF_Tc` \ meth@(_, meth_id) -> - mkTcSig meth_id loc `thenNF_Tc` \ sig_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 + -> [RenamedSig] -- Pragmas (e.g. inline pragmas) + -> MethodSpec -- Details of this method + -> TcM TcMonoBinds + +tcMethodBind xtve inst_tyvars inst_theta avail_insts prags + (sel_id, meth_id, meth_bind) + = -- Check the bindings; first adding inst_tyvars to the envt + -- so that we don't quantify over them in nested places + mkTcSig meth_id `thenM` \ meth_sig -> + + tcExtendTyVarEnv2 xtve ( + addErrCtxt (methodCtxt sel_id) $ + getLIE $ + tcMonoBinds meth_bind [meth_sig] NonRecursive + ) `thenM` \ ((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 + addErrCtxtM (sigCtxt sel_id inst_tyvars inst_theta (idType meth_id)) $ + newDicts SignatureOrigin meth_theta `thenM` \ 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 `thenM` \ lie_binds -> + + checkSigTyVars all_tyvars `thenM` \ all_tyvars' -> + + let + sel_name = idName sel_id + inline_prags = [ (is_inl, phase) + | InlineSig is_inl name phase _ <- prags, + name == sel_name ] + spec_prags = [ prag + | prag@(SpecSig name _ _) <- prags, + name == sel_name] + + -- Attach inline pragmas as appropriate + (final_meth_id, inlines) + | ((is_inline, phase) : _) <- inline_prags + = (meth_id `setInlinePragma` phase, + if is_inline then unitNameSet (idName meth_id) else emptyNameSet) + | otherwise + = (meth_id, emptyNameSet) + + meth_tvs' = take (length meth_tvs) all_tyvars' + poly_meth_bind = AbsBinds meth_tvs' + (map instToId meth_dicts) + [(meth_tvs', final_meth_id, local_meth_id)] + inlines + (lie_binds `andMonoBinds` meth_bind) + + in + -- Deal with specialisation pragmas + -- The sel_name is what appears in the pragma + tcExtendLocalValEnv2 [(sel_name, final_meth_id)] ( + getLIE (tcSpecSigs spec_prags) `thenM` \ (spec_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 [final_meth_id] `thenM` \ spec_binds2 -> + returnM (spec_binds1 `andMonoBinds` spec_binds2) + ) `thenM` \ spec_binds -> + + returnM (poly_meth_bind `andMonoBinds` spec_binds) + + +mkMethodBind :: InstOrigin + -> Class -> [TcType] -- Class and instance types + -> RenamedMonoBinds -- Method binding (pick the right one from in here) + -> ClassOpItem + -> TcM (Maybe Inst, -- Method inst + MethodSpec) +-- Find the binding for the specified method, or make +-- up a suitable default method if it isn't there + +mkMethodBind origin clas inst_tys meth_binds (sel_id, dm_info) + = mkMethId origin clas sel_id inst_tys `thenM` \ (mb_inst, meth_id) -> let 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 + getSrcLocM `thenM` \ loc -> (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 -> - returnTc (FunMonoBind meth_name False -- Not infix decl - [mkSimpleMatch [] rhs Nothing 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) + Just user_bind -> returnM user_bind + Nothing -> mkDefMethRhs origin clas inst_tys sel_id loc dm_info `thenM` \ rhs -> + returnM (FunMonoBind meth_name False -- Not infix decl + [mkSimpleMatch [] rhs placeHolderType loc] loc) + ) `thenM` \ meth_bind -> + + returnM (mb_inst, (sel_id, meth_id, meth_bind)) + +mkMethId :: InstOrigin -> Class + -> Id -> [TcType] -- Selector, and instance types + -> TcM (Maybe Inst, Id) + +-- mkMethId instantiates the selector Id at the specified types +mkMethId origin clas sel_id inst_tys + = let + (tyvars,rho) = tcSplitForAllTys (idType sel_id) + rho_ty = ASSERT( length tyvars == length inst_tys ) + substTyWith tyvars inst_tys rho + (preds,tau) = tcSplitPhiTy rho_ty + first_pred = head preds + in + -- The first predicate should be of form (C a b) + -- where C is the class in question + ASSERT( not (null preds) && + case getClassPredTys_maybe first_pred of + { Just (clas1,tys) -> clas == clas1 ; Nothing -> False } + ) + if isSingleton preds then + -- If it's the only one, make a 'method' + getInstLoc origin `thenM` \ inst_loc -> + newMethod inst_loc sel_id inst_tys preds tau `thenM` \ meth_inst -> + returnM (Just meth_inst, instToId meth_inst) + else + -- If it's not the only one we need to be careful + -- For example, given 'op' defined thus: + -- class Foo a where + -- op :: (?x :: String) => a -> a + -- (mkMethId op T) should return an Inst with type + -- (?x :: String) => T -> T + -- That is, the class-op's context is still there. + -- BUT: it can't be a Method any more, because it breaks + -- INVARIANT 2 of methods. (See the data decl for Inst.) + newUnique `thenM` \ uniq -> + getSrcLocM `thenM` \ loc -> + let + real_tau = mkPhiTy (tail preds) tau + meth_id = mkUserLocal (getOccName sel_id) uniq real_tau loc + in + returnM (Nothing, meth_id) -- 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)) + traceRn (text "mkDefMeth" <+> ppr dm_name) `thenM_` + returnM (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_` - returnTc error_rhs + doptM Opt_WarnMissingMethods `thenM` \ warn -> + warnTc (isInstDecl origin + && warn + && reportIfUnused (getOccName sel_id)) + (omittedMethodWarn sel_id) `thenM_` + returnM error_rhs where - error_rhs = HsApp (HsVar (getName nO_METHOD_BINDING_ERROR_ID)) - (HsLit (HsString (_PK_ error_msg))) + error_rhs = HsLam (mkSimpleMatch wild_pats simple_rhs placeHolderType loc) + simple_rhs = HsApp (HsVar (getName nO_METHOD_BINDING_ERROR_ID)) + (HsLit (HsStringPrim (mkFastString (stringToUtf8 error_msg)))) error_msg = showSDoc (hcat [ppr loc, text "|", ppr sel_id ]) - -mkDefMethRhs is_inst_decl clas inst_tys sel_id loc GenDefMeth + -- When the type is of form t1 -> t2 -> t3 + -- make a default method like (\ _ _ -> noMethBind "blah") + -- rather than simply (noMethBind "blah") + -- Reason: if t1 or t2 are higher-ranked types we get n + -- silly ambiguity messages. + -- Example: f :: (forall a. Eq a => a -> a) -> Int + -- f = error "urk" + -- Here, tcSub tries to force (error "urk") to have the right type, + -- thus: f = \(x::forall a. Eq a => a->a) -> error "urk" (x t) + -- where 't' is fresh ty var. This leads directly to "ambiguous t". + -- + -- NB: technically this changes the meaning of the default-default + -- method slightly, because `seq` can see the lambdas. Oh well. + (_,_,tau1) = tcSplitSigmaTy (idType sel_id) + (_,_,tau2) = tcSplitSigmaTy tau1 + -- Need two splits because the selector can have a type like + -- forall a. Foo a => forall b. Eq b => ... + (arg_tys, _) = tcSplitFunTys tau2 + wild_pats = [WildPat placeHolderType | ty <- arg_tys] + +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_` + ASSERT( isInstDecl origin ) -- We never get here from a class decl + + checkTc (isJust maybe_tycon) + (badGenericInstance sel_id (notSimple inst_tys)) `thenM_` + checkTc (isJust (tyConGenInfo tycon)) + (badGenericInstance sel_id (notGeneric tycon)) `thenM_` - ioToTc (dumpIfSet opt_PprStyle_Debug "Generic RHS" stuff) `thenNF_Tc_` - returnTc rhs + ioToTcRn (dumpIfSet opt_PprStyle_Debug "Generic RHS" stuff) `thenM_` + returnM rhs where rhs = mkGenericRhs sel_id clas_tyvar tycon @@ -591,14 +651,16 @@ mkDefMethRhs is_inst_decl clas inst_tys sel_id loc GenDefMeth -- case we require that the instance decl is for a single-parameter -- type class with type variable arguments: -- instance (...) => C (T a b) - simple_inst = maybeToBool maybe_tycon 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} @@ -616,10 +678,8 @@ 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} @@ -627,13 +687,6 @@ 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) @@ -644,25 +697,22 @@ 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 because = 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)] + because] + +notSimple inst_tys + = vcat [ptext SLIT("because the instance type(s)"), + nest 2 (ppr inst_tys), + ptext SLIT("is not a simple type of form (T a b c)")] + +notGeneric tycon + = vcat [ptext SLIT("because the instance type constructor") <+> quotes (ppr tycon) <+> + ptext SLIT("was not compiled with -fgenerics")] 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}