X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcClassDcl.lhs;h=8fc8a24e7a522ecce3e255912cc634f8eacee143;hp=3814f239b68f23086018dc3df42e3cf6e8b521a4;hb=HEAD;hpb=e79c9ce01d0ce4412bd4bcd99c8c728a6a2ec569 diff --git a/compiler/typecheck/TcClassDcl.lhs b/compiler/typecheck/TcClassDcl.lhs index 3814f23..8fc8a24 100644 --- a/compiler/typecheck/TcClassDcl.lhs +++ b/compiler/typecheck/TcClassDcl.lhs @@ -7,48 +7,34 @@ Typechecking class declarations \begin{code} module TcClassDcl ( tcClassSigs, tcClassDecl2, - findMethodBind, tcInstanceMethodBody, - mkGenericDefMethBind, getGenericInstances, mkDefMethRdrName, + findMethodBind, instantiateMethod, tcInstanceMethodBody, + mkGenericDefMethBind, tcAddDeclCtxt, badMethodErr, badATErr, omittedATWarn ) where #include "HsVersions.h" 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 Generics +import BuildTyCl( TcMethInfo ) import Class -import TyCon -import Type -import MkId import Id import Name -import Var import NameEnv import NameSet -import OccName -import RdrName +import Var 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 @@ -97,61 +83,43 @@ Death to "ExpandingDicts". %************************************************************************ \begin{code} -tcClassSigs :: Name -- Name of the class +tcClassSigs :: Name -- Name of the class -> [LSig Name] -> LHsBinds Name - -> TcM [TcMethInfo] - -type TcMethInfo = (Name, DefMeth, Type) -- A temporary intermediate, to communicate - -- between tcClassSigs and buildClass + -> TcM ([TcMethInfo], -- Exactly one for each method + NameEnv Type) -- Types of the generic-default methods 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 { gen_dm_prs <- mapM (addLocM tc_gen_sig) gen_sigs + ; let gen_dm_env = mkNameEnv gen_dm_prs + + ; op_info <- mapM (addLocM (tc_sig gen_dm_env)) vanilla_sigs + + ; let op_names = mkNameSet [ n | (n,_,_) <- op_info ] + ; sequence_ [ failWithTc (badMethodErr clas n) + | n <- dm_bind_names, not (n `elemNameSet` op_names) ] + -- Value binding for non class-method (ie no TypeSig) + + ; sequence_ [ failWithTc (badGenericMethod clas n) + | (n,_) <- gen_dm_prs, not (n `elem` dm_bind_names) ] + -- Generic signature without value binding + + ; return (op_info, gen_dm_env) } 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) + vanilla_sigs = [L loc (nm,ty) | L loc (TypeSig nm ty) <- sigs] + gen_sigs = [L loc (nm,ty) | L loc (GenericSig nm ty) <- sigs] + 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] + + tc_sig genop_env (L _ op_name, op_hs_ty) + = do { op_ty <- tcHsKindedType op_hs_ty -- Class tyvars already in scope + ; let dm | op_name `elemNameEnv` genop_env = GenericDM + | op_name `elem` dm_bind_names = VanillaDM + | otherwise = NoDM + ; return (op_name, dm, op_ty) } + + tc_gen_sig (L _ op_name, gen_hs_ty) + = do { gen_op_ty <- tcHsKindedType gen_hs_ty + ; return (op_name, gen_op_ty) } \end{code} @@ -163,12 +131,12 @@ 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 $ + = recoverM (return emptyLHsBinds) $ + setSrcSpan loc $ do { clas <- tcLookupLocatedClass class_name -- We make a separate binding for each default method. @@ -181,133 +149,144 @@ 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 - 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 - ; let tc_dm = tcDefMeth rigid_info clas clas_tyvars [pred] - this_dict default_binds + ; traceTc "TIM2" (ppr sigs) + ; let tc_dm = tcDefMeth clas clas_tyvars + this_dict 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 (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.) - ; (defm_binds, dm_ids) <- tcExtendTyVarEnv clas_tyvars $ - mapAndUnzipM tc_dm dm_sel_ids + ; dm_binds <- tcExtendTyVarEnv clas_tyvars $ + mapM tc_dm op_items - ; return (unionManyBags defm_binds, dm_ids) } + ; return (unionManyBags dm_binds) } tcClassDecl2 d = pprPanic "tcClassDecl2" (ppr d) -tcDefMeth :: SkolemInfo -> Class -> [TyVar] -> ThetaType -> Inst -> LHsBinds Name - -> TcSigFun -> TcPragFun -> Id - -> TcM (LHsBinds Id, Id) -tcDefMeth rigid_info clas tyvars theta this_dict binds_in sig_fn prag_fn sel_id - = do { let sel_name = idName sel_id - ; local_dm_name <- newLocalName sel_name - ; 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 - - meth_sig_fn _ = sig_fn sel_name - meth_prag_fn _ = prag_fn sel_name - - ; (top_dm_id, bind) <- tcInstanceMethodBody rigid_info - clas tyvars [this_dict] theta (mkTyVarTys tyvars) - Nothing sel_id - local_dm_name - meth_sig_fn meth_prag_fn - meth_bind - - ; return (bind, top_dm_id) } - -mkDefMethRdrName :: Name -> RdrName -mkDefMethRdrName sel_name = mkDerivedRdrName sel_name mkDefaultMethodOcc +tcDefMeth :: Class -> [TyVar] -> EvVar -> LHsBinds 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 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 + GenDefMeth dm_name -> tc_dm dm_name + 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) ---------------------------- --- 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 - -> LHsBinds Name -- A group of bindings - -> Maybe (LHsBind Name) -- The binding, with meth_name replacing sel_name -findMethodBind sel_name meth_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 + -- 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 + = do { dm_id <- tcLookupId dm_name + ; local_dm_name <- newLocalName sel_name + -- Base the local_dm_name on the selector name, because + -- type errors from tcInstanceMethodBody come from here + + ; let local_dm_ty = instantiateMethod clas dm_id (mkTyVarTys tyvars) + 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) } --------------- -tcInstanceMethodBody :: SkolemInfo -> Class -> [TcTyVar] -> [Inst] - -> TcThetaType -> [TcType] - -> Maybe (Inst, LHsBind Id) -> Id - -> Name -- The local method name - -> TcSigFun -> TcPragFun -> LHsBind Name - -> TcM (Id, LHsBinds Id) -tcInstanceMethodBody rigid_info clas tyvars dfun_dicts theta inst_tys - mb_this_bind sel_id local_meth_name - sig_fn prag_fn bind@(L loc _) - = do { let (sel_tyvars,sel_rho) = tcSplitForAllTys (idType sel_id) - rho_ty = ASSERT( length sel_tyvars == length inst_tys ) - substTyWith sel_tyvars inst_tys sel_rho - - (first_pred, local_meth_ty) = tcSplitPredFunTy_maybe rho_ty - `orElse` pprPanic "tcInstanceMethod" (ppr sel_id) - - local_meth_id = mkLocalId local_meth_name local_meth_ty - meth_ty = mkSigmaTy tyvars theta local_meth_ty - sel_name = idName sel_id - - -- The first predicate should be of form (C a b) - -- where C is the class in question - ; MASSERT( case getClassPredTys_maybe first_pred of - { Just (clas1, _tys) -> clas == clas1 ; Nothing -> False } ) - - -- Typecheck the binding, first extending the envt +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 sig_fn prag_fn - NonRecursive NonRecursive - (unitBag bind) - - ; meth_id <- case rigid_info of - ClsSkol _ -> do { dm_name <- lookupTopBndrRn (mkDefMethRdrName sel_name) - ; return (mkDefaultMethodId dm_name meth_ty) } - _other -> do { meth_name <- newLocalName sel_name - ; return (mkLocalId meth_name meth_ty) } - - ; let (avails, this_dict_bind) - = case mb_this_bind of - Nothing -> (dfun_dicts, emptyBag) - Just (this, bind) -> (this : dfun_dicts, unitBag bind) - - ; inst_loc <- getInstLoc (SigOrigin rigid_info) - ; lie_binds <- tcSimplifyCheck inst_loc tyvars avails lie - - ; let full_bind = L loc $ - AbsBinds tyvars dfun_lam_vars - [(tyvars, meth_id, local_meth_id, [])] - (this_dict_bind `unionBags` lie_binds - `unionBags` tc_bind) - - dfun_lam_vars = map instToVar dfun_dicts -- Includes equalities - - ; return (meth_id, unitBag 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} +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 + + (first_pred, local_meth_ty) = tcSplitPredFunTy_maybe rho_ty + `orElse` pprPanic "tcInstanceMethod" (ppr sel_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 + + +--------------------------- +findMethodBind :: Name -- Selector name + -> LHsBinds Name -- A group of bindings + -> Maybe (LHsBind Name) -- The binding +findMethodBind sel_name binds + = foldlBag mplus Nothing (mapBag f binds) + where + f bind@(L _ (FunBind { fun_id = L _ op_name })) + | op_name == sel_name + = Just bind + f _other = Nothing \end{code} Note [Polymorphic methods] @@ -366,180 +345,23 @@ 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 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]) } - 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 - - ---------------------------- -getGenericInstances :: [LTyClDecl Name] -> TcM [InstInfo Name] -getGenericInstances class_decls - = do { gen_inst_infos <- mapM (addLocM get_generics) class_decls - ; let { gen_inst_info = concat gen_inst_infos } - - -- Return right away if there is no generic stuff - ; if null gen_inst_info then return [] - else do - - -- Otherwise print it out - { dflags <- getDOpts - ; liftIO (dumpIfSet_dyn dflags Opt_D_dump_deriv "Generic instances" - (vcat (map pprInstInfoDetails gen_inst_info))) - ; return gen_inst_info }} - -get_generics :: TyClDecl Name -> TcM [InstInfo Name] -get_generics decl@(ClassDecl {tcdLName = class_name, tcdMeths = def_methods}) - | null generic_binds - = return [] -- The comon case: no generic default methods - - | otherwise -- A source class decl with generic default methods - = recoverM (return []) $ - tcAddDeclCtxt decl $ do - clas <- tcLookupLocatedClass class_name - - -- Group by type, and - -- make an InstInfo out of each group - let - groups = groupWith listToBag generic_binds - - inst_infos <- mapM (mkGenericInstance clas) groups - - -- Check that there is only one InstInfo for each type constructor - -- The main way this can fail is if you write - -- f {| a+b |} ... = ... - -- f {| x+y |} ... = ... - -- Then at this point we'll have an InstInfo for each - -- - -- The class should be unary, which is why simpleInstInfoTyCon should be ok - let - tc_inst_infos :: [(TyCon, InstInfo Name)] - tc_inst_infos = [(simpleInstInfoTyCon i, i) | i <- inst_infos] - - bad_groups = [group | group <- equivClassesByUniq get_uniq tc_inst_infos, - group `lengthExceeds` 1] - get_uniq (tc,_) = getUnique tc - - mapM (addErrTc . dupGenericInsts) bad_groups - - -- Check that there is an InstInfo for each generic type constructor - let - missing = genericTyConNames `minusList` [tyConName tc | (tc,_) <- tc_inst_infos] - - checkTc (null missing) (missingGenericInstances missing) - - return inst_infos + ; return (noLoc $ mkFunBind (noLoc (idName sel_id)) + [mkSimpleMatch [] rhs]) } where - generic_binds :: [(HsType Name, LHsBind Name)] - generic_binds = getGenericBinds def_methods -get_generics decl = pprPanic "get_generics" (ppr decl) - - ---------------------------------- -getGenericBinds :: LHsBinds Name -> [(HsType Name, LHsBind Name)] - -- Takes a group of method bindings, finds the generic ones, and returns - -- them in finite map indexed by the type parameter in the definition. -getGenericBinds binds = concat (map getGenericBind (bagToList binds)) - -getGenericBind :: LHsBindLR Name Name -> [(HsType Name, LHsBindLR Name Name)] -getGenericBind (L loc bind@(FunBind { fun_matches = MatchGroup matches ty })) - = groupWith wrap (mapCatMaybes maybeGenericMatch matches) - where - wrap ms = L loc (bind { fun_matches = MatchGroup ms ty }) -getGenericBind _ - = [] - -groupWith :: ([a] -> b) -> [(HsType Name, a)] -> [(HsType Name, b)] -groupWith _ [] = [] -groupWith op ((t,v):prs) = (t, op (v:vs)) : groupWith op rest - where - vs = map snd this - (this,rest) = partition same_t prs - same_t (t', _v) = t `eqPatType` t' - -eqPatLType :: LHsType Name -> LHsType Name -> Bool -eqPatLType t1 t2 = unLoc t1 `eqPatType` unLoc t2 - -eqPatType :: HsType Name -> HsType Name -> Bool --- A very simple equality function, only for --- type patterns in generic function definitions. -eqPatType (HsTyVar v1) (HsTyVar v2) = v1==v2 -eqPatType (HsAppTy s1 t1) (HsAppTy s2 t2) = s1 `eqPatLType` s2 && t1 `eqPatLType` t2 -eqPatType (HsOpTy s1 op1 t1) (HsOpTy s2 op2 t2) = s1 `eqPatLType` s2 && t1 `eqPatLType` t2 && unLoc op1 == unLoc op2 -eqPatType (HsNumTy n1) (HsNumTy n2) = n1 == n2 -eqPatType (HsParTy t1) t2 = unLoc t1 `eqPatType` t2 -eqPatType t1 (HsParTy t2) = t1 `eqPatType` unLoc t2 -eqPatType _ _ = False - ---------------------------------- -mkGenericInstance :: Class - -> (HsType Name, LHsBinds Name) - -> TcM (InstInfo Name) - -mkGenericInstance clas (hs_ty, binds) = do - -- Make a generic instance declaration - -- For example: instance (C a, C b) => C (a+b) where { binds } - - -- Extract the universally quantified type variables - -- 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))) - hs_forall_ty = noLoc $ mkExplicitHsForAllTy sig_tvs (noLoc []) (noLoc hs_ty) - - -- Type-check the instance type, and check its form - forall_inst_ty <- tcHsSigType GenPatCtxt hs_forall_ty - let - (tyvars, inst_ty) = tcSplitForAllTys forall_inst_ty - - checkTc (validGenericInstanceType inst_ty) - (badGenericInstanceType binds) - - -- Make the dictionary function. - span <- getSrcSpanM - overlap_flag <- getOverlapFlag - dfun_name <- newDFunName clas [inst_ty] span - 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 - - return (InstInfo { iSpec = ispec, iBinds = VanillaInst binds [] }) + rhs = nlHsVar dm_name \end{code} - %************************************************************************ %* * Error messages @@ -570,6 +392,11 @@ 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), @@ -578,27 +405,11 @@ badATErr clas at 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 @@ -607,13 +418,15 @@ 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}