X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcClassDcl.lhs;h=839a5a276b999810597512b152e4e000d22d707d;hp=c3edcc4ca752ceeb97eb4296ab0082cecc8b1eff;hb=b10d7d079ec9c3fc22d4700fe484dd297bddb805;hpb=f16dbbbe59cf3aa19c5fd384560a1b89076d7bc8 diff --git a/compiler/typecheck/TcClassDcl.lhs b/compiler/typecheck/TcClassDcl.lhs index c3edcc4..839a5a2 100644 --- a/compiler/typecheck/TcClassDcl.lhs +++ b/compiler/typecheck/TcClassDcl.lhs @@ -7,8 +7,8 @@ Typechecking class declarations \begin{code} module TcClassDcl ( tcClassSigs, tcClassDecl2, - findMethodBind, tcMethodBind, - mkGenericDefMethBind, getGenericInstances, mkDefMethRdrName, + findMethodBind, instantiateMethod, tcInstanceMethodBody, + mkGenericDefMethBind, getGenericInstances, tcAddDeclCtxt, badMethodErr, badATErr, omittedATWarn ) where @@ -17,42 +17,40 @@ module TcClassDcl ( tcClassSigs, tcClassDecl2, import HsSyn import RnHsSyn import RnExpr -import RnEnv import Inst import InstEnv +import TcPat( addInlinePrags ) import TcEnv import TcBinds +import TcUnify import TcHsType import TcMType import TcType import TcRnMonad +import BuildTyCl( TcMethInfo ) import Generics import Class import TyCon -import Type import MkId import Id import Name import Var import NameEnv import NameSet -import OccName -import RdrName import Outputable import PrelNames import DynFlags import ErrUtils import Util -import Unique import ListSetOps import SrcLoc import Maybes -import List import BasicTypes import Bag import FastString import Control.Monad +import Data.List \end{code} @@ -101,54 +99,44 @@ tcClassSigs :: Name -- Name of the class -> LHsBinds Name -> TcM [TcMethInfo] -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 } + = do { dm_env <- mapM (addLocM (checkDefaultBind clas op_names)) + (bagToList def_methods) + ; mapM (tcClassSig (mkNameEnv 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) +checkDefaultBind :: Name -> [Name] -> HsBindLR Name Name -> TcM (Name, DefMethSpec) -- 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) + 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) + ; case (none_generic, all_generic) of + (True, _) -> return (op, VanillaDM) + (_, True) -> return (op, GenericDM) + _ -> failWith (mixedGenericErr op) } 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; +tcClassSig :: NameEnv DefMethSpec -- 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 + ; let dm = lookupNameEnv dm_env op_name `orElse` NoDM ; return (op_name, dm, op_ty) } tcClassSig _ s = pprPanic "tcClassSig" (ppr s) \end{code} @@ -162,13 +150,13 @@ tcClassSig _ s = pprPanic "tcClassSig" (ppr s) \begin{code} tcClassDecl2 :: LTyClDecl Name -- The class declaration - -> TcM (LHsBinds Id, [Id]) + -> TcM (LHsBinds Id) tcClassDecl2 (L loc (ClassDecl {tcdLName = class_name, tcdSigs = sigs, tcdMeths = default_binds})) - = recoverM (return (emptyLHsBinds, [])) $ - setSrcSpan loc $ do - clas <- tcLookupLocatedClass class_name + = recoverM (return emptyLHsBinds) $ + setSrcSpan loc $ + do { clas <- tcLookupLocatedClass class_name -- We make a separate binding for each default method. -- At one time I used a single AbsBinds for all of them, thus @@ -178,100 +166,151 @@ tcClassDecl2 (L loc (ClassDecl {tcdLName = class_name, tcdSigs = sigs, -- 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 - let - (tyvars, _, _, op_items) = classBigSig clas - rigid_info = ClsSkol clas - prag_fn = mkPragFun sigs - sig_fn = mkTcSigFun sigs - clas_tyvars = tcSkolSigTyVars rigid_info tyvars - tc_dm = tcDefMeth clas_tyvars default_binds - 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 - -- (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.) - - (defm_binds, dm_ids) <- mapAndUnzipM tc_dm dm_sel_ids - return (unionManyBags defm_binds, dm_ids) + ; let + (tyvars, _, _, op_items) = classBigSig clas + rigid_info = ClsSkol clas + prag_fn = mkPragFun sigs default_binds + sig_fn = mkSigFun sigs + clas_tyvars = tcSkolSigTyVars rigid_info tyvars + pred = mkClassPred clas (mkTyVarTys clas_tyvars) + ; this_dict <- newEvVar pred + + ; let tc_dm = tcDefMeth clas clas_tyvars + this_dict default_binds + sig_fn prag_fn + + ; dm_binds <- tcExtendTyVarEnv clas_tyvars $ + mapM tc_dm op_items + + ; return (listToBag (catMaybes dm_binds)) } + tcClassDecl2 d = pprPanic "tcClassDecl2" (ppr d) -tcDefMeth :: [TyVar] -> LHsBinds Name - -> TcSigFun -> TcPragFun -> Id - -> TcM (LHsBinds Id, Id) -tcDefMeth tyvars binds_in sig_fn prag_fn sel_id - = do { let sel_name = idName sel_id - ; dm_name <- lookupTopBndrRn (mkDefMethRdrName sel_name) - ; uniq <- newUnique - ; let dm_ty = idType sel_id -- Same as dict selector! - local_dm_name = setNameUnique sel_name uniq - local_dm_id = mkLocalId local_dm_name dm_ty - top_dm_id = mkDefaultMethodId dm_name dm_ty - all_tvs = map tyVarName tyvars ++ (sig_fn sel_name `orElse` []) - -- Tyvars in scope are *both* the ones from the - -- class decl *and* ones from the method sig - - ; let meth_bind = findMethodBind sel_name local_dm_name binds_in +tcDefMeth :: Class -> [TyVar] -> EvVar -> LHsBinds Name + -> SigFun -> PragFun -> ClassOpItem + -> TcM (Maybe (LHsBind Id)) +-- 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 sig_fn prag_fn (sel_id, dm_info) + = case dm_info of + NoDefMeth -> return Nothing + GenDefMeth -> return Nothing + DefMeth dm_name -> do + { let sel_name = idName sel_id + ; local_dm_name <- newLocalName sel_name + -- Base the local_dm_name on the selector name, because + -- type errors from tcInstanceMethodBody come from here + + -- See Note [Silly default-method bind] + -- (possibly out of date) + + ; let meth_bind = findMethodBind sel_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_info = DefMeth dm_name only if there is a binding in binds_in + + dm_sig_fn _ = sig_fn sel_name + dm_id = mkDefaultMethodId sel_id dm_name + local_dm_type = instantiateMethod clas sel_id (mkTyVarTys tyvars) + local_dm_id = mkLocalId local_dm_name local_dm_type + prags = prag_fn sel_name + + ; 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)) + + ; liftM Just $ + tcInstanceMethodBody (ClsSkol clas) + tyvars + [this_dict] + Nothing + dm_id_w_inline local_dm_id + dm_sig_fn IsDefaultMethod meth_bind } + +--------------- +tcInstanceMethodBody :: SkolemInfo -> [TcTyVar] -> [EvVar] + -> Maybe EvBind + -> Id -> Id + -> SigFun -> TcSpecPrags -> LHsBind Name + -> TcM (LHsBind Id) +tcInstanceMethodBody skol_info tyvars dfun_ev_vars + this_dict 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 + let full_given = case this_dict of + Nothing -> dfun_ev_vars + Just (EvBind dict _) -> dict : dfun_ev_vars + lm_bind = L loc (bind { fun_id = L loc (idName local_meth_id) }) + -- Substitue the local_meth_name for the binder + -- NB: the binding is always a FunBind + + ; (ev_binds, (tc_bind, _)) + <- checkConstraints skol_info tyvars full_given $ + tcExtendIdEnv [local_meth_id] $ + tcPolyBinds TopLevel meth_sig_fn no_prag_fn + NonRecursive NonRecursive + [lm_bind] + + -- Add the binding for this_dict, if we have one + ; ev_binds' <- case this_dict of + Nothing -> return ev_binds + Just (EvBind self rhs) -> extendTcEvBinds ev_binds self rhs + + ; 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} - ; tc_meth_bind <- tcMethodBind all_tvs (prag_fn sel_name) - local_dm_id meth_bind +\begin{code} +instantiateMethod :: Class -> Id -> [TcType] -> TcType +-- Take a class operation, say +-- op :: forall ab. C a => forall c. Ix c => (b,c) -> a +-- Instantiate it at [ty1,ty2] +-- Return the "local method type": +-- forall c. Ix x => (ty2,c) -> ty1 +instantiateMethod clas sel_id inst_tys + = ASSERT( ok_first_pred ) local_meth_ty + where + (sel_tyvars,sel_rho) = tcSplitForAllTys (idType sel_id) + rho_ty = ASSERT( length sel_tyvars == length inst_tys ) + substTyWith sel_tyvars inst_tys sel_rho - -- See Note [Silly default-method bind] - ; let loc = getLoc meth_bind - top_bind = L loc $ VarBind top_dm_id $ - L loc $ HsWrap (WpLet tc_meth_bind) $ - HsVar local_dm_id + (first_pred, local_meth_ty) = tcSplitPredFunTy_maybe rho_ty + `orElse` pprPanic "tcInstanceMethod" (ppr sel_id) - ; return (unitBag top_bind, top_dm_id) } + ok_first_pred = case getClassPredTys_maybe first_pred of + Just (clas1, _tys) -> clas == clas1 + Nothing -> False + -- The first predicate should be of form (C a b) + -- where C is the class in question -mkDefMethRdrName :: Name -> RdrName -mkDefMethRdrName sel_name = mkDerivedRdrName sel_name mkDefaultMethodOcc --------------------------- --- 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 - ---------------------------- -tcMethodBind :: [Name] -> [LSig Name] -> Id - -> LHsBind Name -> TcM (LHsBinds Id) -tcMethodBind tyvars prags meth_id bind - = do { let sig_fn _ = Just tyvars - prag_fn _ = prags - - -- Typecheck the binding, first extending the envt - -- so that when tcInstSig looks up the meth_id to find - -- its signature, we'll find it in the environment - -- - -- If scoped type variables is on, they are brought - -- into scope by tcPolyBinds (via sig_fn) - -- - -- See Note [Polymorphic methods] - ; traceTc (text "tcMethodBind" <+> ppr meth_id <+> ppr tyvars) - ; (tc_binds, ids) <- tcExtendIdEnv [meth_id] $ - tcPolyBinds TopLevel sig_fn prag_fn - NonRecursive NonRecursive - (unitBag bind) - - ; ASSERT( ids == [meth_id] ) -- Binding for ONE method - return (unionManyBags tc_binds) } + f bind@(L _ (FunBind { fun_id = L _ op_name })) + | op_name == sel_name + = Just bind + f _other = Nothing \end{code} Note [Polymorphic methods] @@ -294,8 +333,9 @@ Note [Silly default-method bind] When we pass the default method binding to the type checker, it must look like op2 = e not $dmop2 = e -otherwise the "$dm" stuff comes out in the interface file. So we -typecheck the former, and wrap it in a let, thus +otherwise the "$dm" stuff comes out error messages. But we want the +"$dm" to come out in the interface file. So we typecheck the former, +and wrap it in a let, thus $dmop2 = let op2 = e in op2 This makes the error messages right. @@ -329,10 +369,9 @@ gives rise to the instance declarations instance C 1 where op Unit = ... - \begin{code} -mkGenericDefMethBind :: Class -> [Type] -> Id -> Name -> TcM (LHsBind Name) -mkGenericDefMethBind clas inst_tys sel_id meth_name +mkGenericDefMethBind :: Class -> [Type] -> Id -> TcM (LHsBind Name) +mkGenericDefMethBind clas inst_tys sel_id = -- 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 @@ -350,7 +389,8 @@ mkGenericDefMethBind clas inst_tys sel_id meth_name -- 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 [] rn_rhs]) } where rhs = mkGenericRhs sel_id clas_tyvar tycon @@ -415,7 +455,7 @@ get_generics decl@(ClassDecl {tcdLName = class_name, tcdMeths = def_methods}) group `lengthExceeds` 1] get_uniq (tc,_) = getUnique tc - mapM (addErrTc . dupGenericInsts) bad_groups + mapM_ (addErrTc . dupGenericInsts) bad_groups -- Check that there is an InstInfo for each generic type constructor let @@ -479,7 +519,8 @@ mkGenericInstance clas (hs_ty, binds) = do -- and wrap them as forall'd tyvars, so that kind inference -- works in the standard way let - sig_tvs = map (noLoc.UserTyVar) (nameSetToList (extractHsTyVars (noLoc hs_ty))) + sig_tvs = userHsTyVarBndrs $ map noLoc $ nameSetToList $ + extractHsTyVars (noLoc hs_ty) hs_forall_ty = noLoc $ mkExplicitHsForAllTy sig_tvs (noLoc []) (noLoc hs_ty) -- Type-check the instance type, and check its form @@ -499,7 +540,7 @@ mkGenericInstance clas (hs_ty, binds) = do dfun_id = mkDictFunId dfun_name tyvars inst_theta clas [inst_ty] ispec = mkLocalInstance dfun_id overlap_flag - return (InstInfo { iSpec = ispec, iBinds = VanillaInst binds [] }) + return (InstInfo { iSpec = ispec, iBinds = VanillaInst binds [] False }) \end{code} @@ -561,7 +602,7 @@ notGeneric tycon 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 @@ -570,7 +611,7 @@ 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