X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcClassDcl.lhs;h=e4dbf5c0c082281cbdcf2fcd860418a14d45f662;hb=fbff1b7b9c89f6369c4394a0b10fa7c06e011698;hp=0fb82cb76a305eafc156c0f1da378b377857e1f1;hpb=836b1e90821aacc9d1e09fe78085f911597274c8;p=ghc-hetmet.git diff --git a/compiler/typecheck/TcClassDcl.lhs b/compiler/typecheck/TcClassDcl.lhs index 0fb82cb..e4dbf5c 100644 --- a/compiler/typecheck/TcClassDcl.lhs +++ b/compiler/typecheck/TcClassDcl.lhs @@ -8,7 +8,7 @@ Typechecking class declarations \begin{code} module TcClassDcl ( tcClassSigs, tcClassDecl2, findMethodBind, instantiateMethod, tcInstanceMethodBody, - mkGenericDefMethBind, getGenericInstances, mkDefMethRdrName, + mkGenericDefMethBind, getGenericInstances, tcAddDeclCtxt, badMethodErr, badATErr, omittedATWarn ) where @@ -16,17 +16,17 @@ module TcClassDcl ( tcClassSigs, tcClassDecl2, import HsSyn import RnHsSyn -import RnExpr -import RnEnv import Inst import InstEnv import TcEnv +import TcPat( addInlinePrags ) import TcBinds -import TcSimplify +import TcUnify import TcHsType import TcMType import TcType import TcRnMonad +import BuildTyCl( TcMethInfo ) import Generics import Class import TyCon @@ -34,9 +34,7 @@ import MkId import Id import Name import Var -import NameEnv import NameSet -import RdrName import Outputable import PrelNames import DynFlags @@ -97,58 +95,36 @@ Death to "ExpandingDicts". tcClassSigs :: Name -- Name of the class -> [LSig Name] -> LHsBinds Name - -> TcM [TcMethInfo] + -> TcM [TcMethInfo] -- One for each method -type TcMethInfo = (Name, DefMeth, Type) -- A temporary intermediate, to communicate - -- between tcClassSigs and buildClass tcClassSigs clas sigs def_methods - = do { dm_env <- checkDefaultBinds clas op_names def_methods - ; mapM (tcClassSig dm_env) op_sigs } - where - op_sigs = [sig | sig@(L _ (TypeSig _ _)) <- sigs] - op_names = [n | (L _ (TypeSig (L _ n) _)) <- op_sigs] - - -checkDefaultBinds :: Name -> [Name] -> LHsBinds Name -> TcM (NameEnv Bool) - -- 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 Bool - -- where True <=> it's a generic default method -checkDefaultBinds clas ops binds - = do dm_infos <- mapM (addLocM (checkDefaultBind clas ops)) (bagToList binds) - return (mkNameEnv dm_infos) - -checkDefaultBind :: Name -> [Name] -> HsBindLR Name Name -> TcM (Name, Bool) -checkDefaultBind clas ops (FunBind {fun_id = L _ op, fun_matches = MatchGroup matches _ }) - = do { -- Check that the op is from this class - checkTc (op `elem` ops) (badMethodErr clas op) - - -- Check that all the defns ar generic, or none are - ; checkTc (all_generic || none_generic) (mixedGenericErr op) - - ; return (op, all_generic) - } + = do { -- Check that all def_methods are in the class + ; op_info <- mapM (addLocM tc_sig) [sig | sig@(L _ (TypeSig _ _)) <- sigs] + ; let op_names = [ n | (n,_,_) <- op_info ] + + ; sequence_ [ failWithTc (badMethodErr clas n) + | n <- dm_bind_names, not (n `elem` op_names) ] + -- Value binding for non class-method (ie no TypeSig) + + ; sequence_ [ failWithTc (badGenericMethod clas n) + | n <- genop_names, not (n `elem` dm_bind_names) ] + -- Generic signature without value binding + + ; return op_info } where - n_generic = count (isJust . maybeGenericMatch) matches - none_generic = n_generic == 0 - all_generic = matches `lengthIs` n_generic -checkDefaultBind _ _ b = pprPanic "checkDefaultBind" (ppr b) - - -tcClassSig :: NameEnv Bool -- Info about default methods; - -> LSig Name - -> TcM TcMethInfo - -tcClassSig dm_env (L loc (TypeSig (L _ op_name) op_hs_ty)) - = setSrcSpan loc $ do - { op_ty <- tcHsKindedType op_hs_ty -- Class tyvars already in scope - ; let dm = case lookupNameEnv dm_env op_name of - Nothing -> NoDefMeth - Just False -> DefMeth - Just True -> GenDefMeth - ; return (op_name, dm, op_ty) } -tcClassSig _ s = pprPanic "tcClassSig" (ppr s) + dm_bind_names :: [Name] -- These ones have a value binding in the class decl + dm_bind_names = [op | L _ (FunBind {fun_id = L _ op}) <- bagToList def_methods] + + genop_names :: [Name] -- These ones have a generic signature + genop_names = [n | L _ (GenericSig (L _ n) _) <- sigs] + + tc_sig (TypeSig (L _ op_name) op_hs_ty) + = do { op_ty <- tcHsKindedType op_hs_ty -- Class tyvars already in scope + ; let dm | op_name `elem` genop_names = GenericDM + | op_name `elem` dm_bind_names = VanillaDM + | otherwise = NoDM + ; return (op_name, dm, op_ty) } + tc_sig sig = pprPanic "tc_cls_sig" (ppr sig) \end{code} @@ -160,12 +136,12 @@ tcClassSig _ s = pprPanic "tcClassSig" (ppr s) \begin{code} tcClassDecl2 :: LTyClDecl Name -- The class declaration - -> TcM ([Id], LHsBinds Id) + -> TcM (LHsBinds Id) tcClassDecl2 (L loc (ClassDecl {tcdLName = class_name, tcdSigs = sigs, tcdMeths = default_binds})) - = recoverM (return ([], emptyLHsBinds)) $ - setSrcSpan loc $ + = recoverM (return emptyLHsBinds) $ + setSrcSpan loc $ do { clas <- tcLookupLocatedClass class_name -- We make a separate binding for each default method. @@ -178,113 +154,130 @@ tcClassDecl2 (L loc (ClassDecl {tcdLName = class_name, tcdSigs = sigs, -- default methods. Better to make separate AbsBinds for each ; let (tyvars, _, _, op_items) = classBigSig clas - rigid_info = ClsSkol clas - prag_fn = mkPragFun sigs default_binds - sig_fn = mkTcSigFun sigs - clas_tyvars = tcSkolSigTyVars rigid_info tyvars + prag_fn = mkPragFun sigs default_binds + sig_fn = mkSigFun sigs + clas_tyvars = tcSuperSkolTyVars tyvars pred = mkClassPred clas (mkTyVarTys clas_tyvars) - ; inst_loc <- getInstLoc (SigOrigin rigid_info) - ; this_dict <- newDictBndr inst_loc pred + ; this_dict <- newEvVar pred + ; traceTc "TIM2" (ppr sigs) ; let tc_dm = tcDefMeth clas clas_tyvars - this_dict default_binds + this_dict default_binds sigs sig_fn prag_fn - -- tc_dm is called only for a sel_id - -- that has a binding in default_binds - dm_sel_ids = [sel_id | (sel_id, DefMeth) <- op_items] - -- Generate code for polymorphic default methods only (hence DefMeth) - -- (Generic default methods have turned into instance decls by now.) - -- This is incompatible with Hugs, which expects a polymorphic - -- default method for every class op, regardless of whether or not - -- 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.) + ; dm_binds <- tcExtendTyVarEnv clas_tyvars $ + mapM tc_dm op_items - ; (dm_ids, defm_binds) <- tcExtendTyVarEnv clas_tyvars $ - mapAndUnzipM tc_dm dm_sel_ids - - ; return (dm_ids, listToBag defm_binds) } + ; return (unionManyBags dm_binds) } tcClassDecl2 d = pprPanic "tcClassDecl2" (ppr d) -tcDefMeth :: Class -> [TyVar] -> Inst -> LHsBinds Name - -> TcSigFun -> TcPragFun -> Id - -> TcM (Id, LHsBind Id) -tcDefMeth clas tyvars this_dict binds_in sig_fn prag_fn sel_id - = do { let sel_name = idName sel_id - ; dm_name <- lookupTopBndrRn (mkDefMethRdrName sel_name) - ; local_dm_name <- newLocalName sel_name - -- Base the local_dm_name on the selector name, becuase - -- type errors from tcInstanceMethodBody come from here - - -- See Note [Silly default-method bind] - -- (possibly out of date) - - ; let meth_bind = findMethodBind sel_name local_dm_name binds_in - `orElse` pprPanic "tcDefMeth" (ppr sel_id) - -- We only call tcDefMeth on selectors for which - -- there is a binding in binds_in - - dm_sig_fn _ = sig_fn sel_name - dm_ty = idType sel_id - dm_id = mkDefaultMethodId dm_name dm_ty - local_dm_type = instantiateMethod clas sel_id (mkTyVarTys tyvars) - local_dm_id = mkLocalId local_dm_name local_dm_type - - ; (dm_id_w_inline, spec_prags) - <- tcPrags NonRecursive False True dm_id (prag_fn sel_name) - - ; warnTc (not (null spec_prags)) - (ptext (sLit "Ignoring SPECIALISE pragmas on default method") - <+> quotes (ppr sel_name)) - - ; tcInstanceMethodBody (instLoc this_dict) - tyvars [this_dict] - ([], emptyBag) - dm_id_w_inline local_dm_id - dm_sig_fn IsDefaultMethod meth_bind } +tcDefMeth :: Class -> [TyVar] -> EvVar -> LHsBinds Name -> [LSig Name] + -> SigFun -> PragFun -> ClassOpItem + -> TcM (LHsBinds TcId) +-- Generate code for polymorphic default methods only (hence DefMeth) +-- (Generic default methods have turned into instance decls by now.) +-- This is incompatible with Hugs, which expects a polymorphic +-- default method for every class op, regardless of whether or not +-- 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 this_dict binds_in sigs sig_fn prag_fn (sel_id, dm_info) + = case dm_info of + NoDefMeth -> do { mapM_ (addLocM (badDmPrag sel_id)) prags + ; return emptyBag } + DefMeth dm_name -> tc_dm dm_name (instantiateMethod clas sel_id (mkTyVarTys tyvars)) + GenDefMeth dm_name -> do { tau <- tc_genop_ty (findGenericSig sigs sel_name) + ; tc_dm dm_name tau } + -- In the case of a generic default, we have to get the type from the signature + -- Otherwise we can get it by instantiating the method selector + where + sel_name = idName sel_id + prags = prag_fn sel_name + dm_sig_fn _ = sig_fn sel_name + dm_bind = findMethodBind sel_name binds_in + `orElse` pprPanic "tcDefMeth" (ppr sel_id) + + -- Eg. class C a where + -- op :: forall b. Eq b => a -> [b] -> a + -- gen_op :: a -> a + -- generic gen_op :: D a => a -> a + -- The "local_dm_ty" is precisely the type in the above + -- type signatures, ie with no "forall a. C a =>" prefix + + tc_dm dm_name local_dm_ty + = do { local_dm_name <- newLocalName sel_name + -- Base the local_dm_name on the selector name, because + -- type errors from tcInstanceMethodBody come from here + + ; let dm_ty = mkSigmaTy tyvars [mkClassPred clas (mkTyVarTys tyvars)] local_dm_ty + dm_id = mkExportedLocalId dm_name dm_ty + local_dm_id = mkLocalId local_dm_name local_dm_ty + + ; dm_id_w_inline <- addInlinePrags dm_id prags + ; spec_prags <- tcSpecPrags dm_id prags + + ; warnTc (not (null spec_prags)) + (ptext (sLit "Ignoring SPECIALISE pragmas on default method") + <+> quotes (ppr sel_name)) + + ; tc_bind <- tcInstanceMethodBody (ClsSkol clas) tyvars [this_dict] + dm_id_w_inline local_dm_id dm_sig_fn + IsDefaultMethod dm_bind + + ; return (unitBag tc_bind) } + + tc_genop_ty :: LHsType Name -> TcM Type + tc_genop_ty hs_ty + = setSrcSpan (getLoc hs_ty) $ + do { tau <- tcHsKindedType hs_ty + ; checkValidType (FunSigCtxt sel_name) tau + ; return tau } + +findGenericSig :: [LSig Name] -> Name -> LHsType Name +-- Find the 'generic op :: ty' signature among the sigs +-- If dm_info is GenDefMeth, the corresponding signature +-- should jolly well exist! Hence the panic +findGenericSig sigs sel_name + = case [lty | L _ (GenericSig (L _ n) lty) <- sigs + , n == sel_name ] of + [lty] -> lty + _ -> pprPanic "tcDefMeth" (ppr sel_name $$ ppr sigs) --------------- -tcInstanceMethodBody :: InstLoc -> [TcTyVar] -> [Inst] - -> ([Inst], LHsBinds Id) -> Id -> Id - -> TcSigFun -> TcSpecPrags -> LHsBind Name - -> TcM (Id, LHsBind Id) -tcInstanceMethodBody inst_loc tyvars dfun_dicts - (this_dict, this_bind) meth_id local_meth_id - meth_sig_fn spec_prags bind@(L loc _) +tcInstanceMethodBody :: SkolemInfo -> [TcTyVar] -> [EvVar] + -> Id -> Id + -> SigFun -> TcSpecPrags -> LHsBind Name + -> TcM (LHsBind Id) +tcInstanceMethodBody skol_info tyvars dfun_ev_vars + meth_id local_meth_id + meth_sig_fn specs + (L loc bind) = do { -- Typecheck the binding, first extending the envt -- so that when tcInstSig looks up the local_meth_id to find -- its signature, we'll find it in the environment - ; ((tc_bind, _), lie) <- getLIE $ - tcExtendIdEnv [local_meth_id] $ - tcPolyBinds TopLevel meth_sig_fn no_prag_fn - NonRecursive NonRecursive - (unitBag bind) - - ; let avails = this_dict ++ dfun_dicts - -- Only need the this_dict stuff if there are type - -- variables involved; otherwise overlap is not possible - -- See Note [Subtle interaction of recursion and overlap] - -- in TcInstDcls - ; lie_binds <- tcSimplifyCheck inst_loc tyvars avails lie - - ; let full_bind = AbsBinds tyvars dfun_lam_vars - [(tyvars, meth_id, local_meth_id, spec_prags)] - (this_bind `unionBags` lie_binds - `unionBags` tc_bind) - - dfun_lam_vars = map instToVar dfun_dicts -- Includes equalities - - ; return (meth_id, L loc full_bind) } + let lm_bind = L loc (bind { fun_id = L loc (idName local_meth_id) }) + -- Substitute the local_meth_name for the binder + -- NB: the binding is always a FunBind + ; traceTc "TIM" (ppr local_meth_id $$ ppr (meth_sig_fn (idName local_meth_id))) + ; (ev_binds, (tc_bind, _)) + <- checkConstraints skol_info tyvars dfun_ev_vars $ + tcExtendIdEnv [local_meth_id] $ + tcPolyBinds TopLevel meth_sig_fn no_prag_fn + NonRecursive NonRecursive + [lm_bind] + + ; let full_bind = AbsBinds { abs_tvs = tyvars, abs_ev_vars = dfun_ev_vars + , abs_exports = [(tyvars, meth_id, local_meth_id, specs)] + , abs_ev_binds = ev_binds + , abs_binds = tc_bind } + + ; return (L loc full_bind) } where no_prag_fn _ = [] -- No pragmas for local_meth_id; -- they are all for meth_id \end{code} \begin{code} -mkDefMethRdrName :: Name -> RdrName -mkDefMethRdrName sel_name = mkDerivedRdrName sel_name mkDefaultMethodOcc - instantiateMethod :: Class -> Id -> [TcType] -> TcType -- Take a class operation, say -- op :: forall ab. C a => forall c. Ix c => (b,c) -> a @@ -309,18 +302,16 @@ instantiateMethod clas sel_id inst_tys --------------------------- --- 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. -findMethodBind :: Name -> Name -- Selector and method name +findMethodBind :: Name -- Selector name -> LHsBinds Name -- A group of bindings - -> Maybe (LHsBind Name) -- The binding, with meth_name replacing sel_name -findMethodBind sel_name meth_name binds + -> Maybe (LHsBind Name) -- The binding +findMethodBind sel_name binds = foldlBag mplus Nothing (mapBag f binds) where - f (L loc1 bind@(FunBind { fun_id = L loc2 op_name })) - | op_name == sel_name - = Just (L loc1 (bind { fun_id = L loc2 meth_name })) - f _other = Nothing + f bind@(L _ (FunBind { fun_id = L _ op_name })) + | op_name == sel_name + = Just bind + f _other = Nothing \end{code} Note [Polymorphic methods] @@ -381,40 +372,19 @@ gives rise to the instance declarations \begin{code} mkGenericDefMethBind :: Class -> [Type] -> Id -> Name -> TcM (LHsBind Name) -mkGenericDefMethBind clas inst_tys sel_id meth_name +mkGenericDefMethBind clas inst_tys sel_id dm_name = -- 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) - do { checkTc (isJust maybe_tycon) - (badGenericInstance sel_id (notSimple inst_tys)) - ; checkTc (tyConHasGenerics tycon) - (badGenericInstance sel_id (notGeneric tycon)) - - ; dflags <- getDOpts + -- If the method is defined generically, we only have to call the + -- dm_name. + do { dflags <- getDOpts ; liftIO (dumpIfSet_dyn dflags Opt_D_dump_deriv "Filling in method body" (vcat [ppr clas <+> ppr inst_tys, nest 2 (ppr sel_id <+> equals <+> ppr rhs)])) - -- Rename it before returning it - ; (rn_rhs, _) <- rnLExpr rhs - ; return (noLoc $ mkFunBind (noLoc meth_name) [mkSimpleMatch [] rn_rhs]) } + ; return (noLoc $ mkFunBind (noLoc (idName sel_id)) + [mkSimpleMatch [] rhs]) } where - rhs = mkGenericRhs sel_id clas_tyvar tycon - - -- The tycon is only used in the generic case, and in that - -- case we require that the instance decl is for a single-parameter - -- type class with type variable arguments: - -- instance (...) => C (T a b) - clas_tyvar = ASSERT (not (null (classTyVars clas))) head (classTyVars clas) - Just tycon = maybe_tycon - maybe_tycon = case inst_tys of - [ty] -> case tcSplitTyConApp_maybe ty of - Just (tycon, arg_tys) | all tcIsTyVarTy arg_tys -> Just tycon - _ -> Nothing - _ -> Nothing - + rhs = nlHsVar dm_name --------------------------- getGenericInstances :: [LTyClDecl Name] -> TcM [InstInfo Name] @@ -427,9 +397,8 @@ getGenericInstances class_decls else do -- Otherwise print it out - { dflags <- getDOpts - ; liftIO (dumpIfSet_dyn dflags Opt_D_dump_deriv "Generic instances" - (vcat (map pprInstInfoDetails gen_inst_info))) + { dumpDerivingInfo $ hang (ptext (sLit "Generic instances")) + 2 (vcat (map pprInstInfoDetails gen_inst_info)) ; return gen_inst_info }} get_generics :: TyClDecl Name -> TcM [InstInfo Name] @@ -547,7 +516,7 @@ mkGenericInstance clas (hs_ty, binds) = do let inst_theta = [mkClassPred clas [mkTyVarTy tv] | tv <- tyvars] dfun_id = mkDictFunId dfun_name tyvars inst_theta clas [inst_ty] - ispec = mkLocalInstance dfun_id overlap_flag + ispec = mkLocalInstance dfun_id overlap_flag return (InstInfo { iSpec = ispec, iBinds = VanillaInst binds [] False }) \end{code} @@ -583,6 +552,11 @@ badMethodErr clas op = hsep [ptext (sLit "Class"), quotes (ppr clas), ptext (sLit "does not have a method"), quotes (ppr op)] +badGenericMethod :: Outputable a => a -> Name -> SDoc +badGenericMethod clas op + = hsep [ptext (sLit "Class"), quotes (ppr clas), + ptext (sLit "has a generic-default signature without a binding"), quotes (ppr op)] + badATErr :: Class -> Name -> SDoc badATErr clas at = hsep [ptext (sLit "Class"), quotes (ppr clas), @@ -592,26 +566,10 @@ omittedATWarn :: Name -> SDoc omittedATWarn at = ptext (sLit "No explicit AT declaration for") <+> quotes (ppr at) -badGenericInstance :: Var -> SDoc -> SDoc -badGenericInstance sel_id because - = sep [ptext (sLit "Can't derive generic code for") <+> quotes (ppr sel_id), - because] - -notSimple :: [Type] -> SDoc -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 a1 ... an)")] - -notGeneric :: TyCon -> SDoc -notGeneric tycon - = vcat [ptext (sLit "because the instance type constructor") <+> quotes (ppr tycon) <+> - ptext (sLit "was not compiled with -XGenerics")] - badGenericInstanceType :: LHsBinds Name -> SDoc badGenericInstanceType binds = vcat [ptext (sLit "Illegal type pattern in the generic bindings"), - nest 4 (ppr binds)] + nest 2 (ppr binds)] missingGenericInstances :: [Name] -> SDoc missingGenericInstances missing @@ -620,13 +578,15 @@ missingGenericInstances missing dupGenericInsts :: [(TyCon, InstInfo a)] -> SDoc dupGenericInsts tc_inst_infos = vcat [ptext (sLit "More than one type pattern for a single generic type constructor:"), - nest 4 (vcat (map ppr_inst_ty tc_inst_infos)), + nest 2 (vcat (map ppr_inst_ty tc_inst_infos)), ptext (sLit "All the type patterns for a generic type constructor must be identical") ] where ppr_inst_ty (_,inst) = ppr (simpleInstInfoTy inst) -mixedGenericErr :: Name -> SDoc -mixedGenericErr op - = ptext (sLit "Can't mix generic and non-generic equations for class method") <+> quotes (ppr op) +badDmPrag :: Id -> Sig Name -> TcM () +badDmPrag sel_id prag + = addErrTc (ptext (sLit "The") <+> hsSigDoc prag <+> ptext (sLit "for default method") + <+> quotes (ppr sel_id) + <+> ptext (sLit "lacks an accompanying binding")) \end{code}