X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcClassDcl.lhs;h=8fc8a24e7a522ecce3e255912cc634f8eacee143;hp=0f91f6b9e7a704b444fef7d2fe0244c2bb1d24ab;hb=HEAD;hpb=47673f2f689b0c3294c119afd217afab1044f213 diff --git a/compiler/typecheck/TcClassDcl.lhs b/compiler/typecheck/TcClassDcl.lhs index 0f91f6b..8fc8a24 100644 --- a/compiler/typecheck/TcClassDcl.lhs +++ b/compiler/typecheck/TcClassDcl.lhs @@ -8,19 +8,15 @@ Typechecking class declarations \begin{code} module TcClassDcl ( tcClassSigs, tcClassDecl2, findMethodBind, instantiateMethod, tcInstanceMethodBody, - mkGenericDefMethBind, getGenericInstances, + mkGenericDefMethBind, tcAddDeclCtxt, badMethodErr, badATErr, omittedATWarn ) where #include "HsVersions.h" import HsSyn -import RnHsSyn -import RnExpr -import Inst -import InstEnv -import TcPat( addInlinePrags ) import TcEnv +import TcPat( addInlinePrags ) import TcBinds import TcUnify import TcHsType @@ -28,21 +24,15 @@ import TcMType import TcType import TcRnMonad import BuildTyCl( TcMethInfo ) -import Generics import Class -import TyCon -import MkId import Id import Name -import Var import NameEnv import NameSet +import Var import Outputable -import PrelNames import DynFlags import ErrUtils -import Util -import ListSetOps import SrcLoc import Maybes import BasicTypes @@ -50,7 +40,6 @@ import Bag import FastString import Control.Monad -import Data.List \end{code} @@ -94,51 +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] - + -> TcM ([TcMethInfo], -- Exactly one for each method + NameEnv Type) -- Types of the generic-default methods tcClassSigs clas sigs def_methods - = 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] - -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 -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 - ; 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 + = do { gen_dm_prs <- mapM (addLocM tc_gen_sig) gen_sigs + ; let gen_dm_env = mkNameEnv gen_dm_prs -checkDefaultBind _ _ b = pprPanic "checkDefaultBind" (ppr b) + ; 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) -tcClassSig :: NameEnv DefMethSpec -- Info about default methods; - -> LSig Name - -> TcM TcMethInfo + ; sequence_ [ failWithTc (badGenericMethod clas n) + | (n,_) <- gen_dm_prs, not (n `elem` dm_bind_names) ] + -- Generic signature without value binding -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 = lookupNameEnv dm_env op_name `orElse` NoDM - ; return (op_name, dm, op_ty) } -tcClassSig _ s = pprPanic "tcClassSig" (ppr s) + ; return (op_info, gen_dm_env) } + where + 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} @@ -168,27 +149,27 @@ 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 + prag_fn = mkPragFun sigs default_binds sig_fn = mkSigFun sigs - clas_tyvars = tcSkolSigTyVars rigid_info tyvars + clas_tyvars = tcSuperSkolTyVars tyvars pred = mkClassPred clas (mkTyVarTys clas_tyvars) ; this_dict <- newEvVar pred + ; traceTc "TIM2" (ppr sigs) ; let tc_dm = tcDefMeth clas clas_tyvars - this_dict default_binds + this_dict default_binds sig_fn prag_fn ; dm_binds <- tcExtendTyVarEnv clas_tyvars $ mapM tc_dm op_items - ; return (listToBag (catMaybes dm_binds)) } + ; return (unionManyBags dm_binds) } tcClassDecl2 d = pprPanic "tcClassDecl2" (ppr d) tcDefMeth :: Class -> [TyVar] -> EvVar -> LHsBinds Name -> SigFun -> PragFun -> ClassOpItem - -> TcM (Maybe (LHsBind Id)) + -> 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 @@ -197,40 +178,45 @@ tcDefMeth :: Class -> [TyVar] -> EvVar -> LHsBinds Name -- (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) - -- 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] - dm_id_w_inline local_dm_id - dm_sig_fn IsDefaultMethod meth_bind } + 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) + + -- 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 -> [TcTyVar] -> [EvVar] @@ -247,7 +233,7 @@ tcInstanceMethodBody skol_info tyvars dfun_ev_vars 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] $ @@ -360,179 +346,22 @@ gives rise to the instance declarations op Unit = ... \begin{code} -mkGenericDefMethBind :: Class -> [Type] -> Id -> TcM (LHsBind Name) -mkGenericDefMethBind clas inst_tys sel_id +mkGenericDefMethBind :: Class -> [Type] -> Id -> Name -> TcM (LHsBind 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 (idName sel_id)) - [mkSimpleMatch [] rn_rhs]) } + [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 - - ---------------------------- -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 - { dumpDerivingInfo $ hang (ptext (sLit "Generic instances")) - 2 (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 - 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 = 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 - 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 [] False }) + rhs = nlHsVar dm_name \end{code} - %************************************************************************ %* * Error messages @@ -563,6 +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), @@ -571,23 +405,7 @@ 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"), @@ -605,8 +423,10 @@ dupGenericInsts tc_inst_infos ] 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}