X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcTyClsDecls.lhs;h=0d29681e92ed8a03092f736efcaf73dda4b93962;hb=550421384b8364cdaf3135f7859c9f7d7ee1fff1;hp=495c0a5fec822b4815fe16d118380cdb4b6ec736;hpb=5cf27e8f1731c52fe63a5b9615f927484164c61b;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcTyClsDecls.lhs b/ghc/compiler/typecheck/TcTyClsDecls.lhs index 495c0a5..0d29681 100644 --- a/ghc/compiler/typecheck/TcTyClsDecls.lhs +++ b/ghc/compiler/typecheck/TcTyClsDecls.lhs @@ -1,323 +1,602 @@ % -% (c) The AQUA Project, Glasgow University, 1996 +% (c) The AQUA Project, Glasgow University, 1996-1998 % \section[TcTyClsDecls]{Typecheck type and class declarations} \begin{code} -#include "HsVersions.h" - module TcTyClsDecls ( - tcTyAndClassDecls1 + tcTyAndClassDecls ) where -import Ubiq{-uitous-} +#include "HsVersions.h" -import HsSyn ( TyDecl(..), ConDecl(..), BangType(..), - ClassDecl(..), MonoType(..), PolyType(..), - Sig(..), MonoBinds, Fake, InPat, HsBinds(..), Bind, HsExpr ) -import RnHsSyn ( isRnTyCon, RenamedTyDecl(..), RenamedClassDecl(..), - RnName(..){-instance Uniquable-} +import HsSyn ( TyClDecl(..), HsConDetails(..), HsTyVarBndr(..), + ConDecl(..), Sig(..), BangType(..), HsBang(..), + tyClDeclTyVars, getBangType, getBangStrictness, + LTyClDecl, tcdName, LHsTyVarBndr ) -import TcHsSyn ( TcHsBinds(..), TcIdOcc(..) ) - -import TcMonad hiding ( rnMtoTcM ) -import Inst ( InstanceMapper(..) ) -import TcClassDcl ( tcClassDecl1 ) -import TcEnv ( tcExtendTyConEnv, tcExtendClassEnv, - tcExtendGlobalValEnv, - tcTyVarScope, tcGetEnv ) -import TcKind ( TcKind, newKindVars ) -import TcTyDecls ( tcTyDecl, mkDataBinds ) - -import Bag -import Class ( Class(..), classSelIds ) -import Digraph ( findSCCs, SCC(..) ) -import Name ( getSrcLoc ) -import PprStyle -import Pretty -import UniqSet ( UniqSet(..), emptyUniqSet, - unitUniqSet, unionUniqSets, - unionManyUniqSets, uniqSetToList ) -import SrcLoc ( SrcLoc ) -import TyCon ( TyCon, tyConDataCons, isDataTyCon, isSynTyCon ) -import Unique ( Unique ) -import Util ( panic, pprTrace ) - +import BasicTypes ( RecFlag(..), NewOrData(..), StrictnessMark(..) ) +import HscTypes ( implicitTyThings ) +import BuildTyCl ( buildClass, buildAlgTyCon, buildSynTyCon, buildDataCon ) +import TcRnMonad +import TcEnv ( TcTyThing(..), TyThing(..), + tcLookupLocated, tcLookupLocatedGlobal, + tcExtendGlobalEnv, + tcExtendRecEnv, tcLookupTyVar ) +import TcTyDecls ( calcTyConArgVrcs, calcRecFlags, calcCycleErrs ) +import TcClassDcl ( tcClassSigs, tcAddDeclCtxt ) +import TcHsType ( kcHsTyVars, kcHsLiftedSigType, kcHsSigType, kcCheckHsType, + kcHsContext, tcTyVarBndrs, tcHsKindedType, tcHsKindedContext ) +import TcMType ( newKindVar, checkValidTheta, checkValidType, checkFreeness, + UserTypeCtxt(..), SourceTyCtxt(..) ) +import TcUnify ( unifyKind ) +import TcType ( TcKind, ThetaType, TcType, tyVarsOfType, + mkArrowKind, liftedTypeKind, + tcSplitSigmaTy, tcEqType ) +import Type ( splitTyConApp_maybe, pprThetaArrow, pprParendType ) +import FieldLabel ( fieldLabelName, fieldLabelType ) +import Generics ( validGenericMethodType, canDoGenerics ) +import Class ( Class, className, classTyCon, DefMeth(..), classBigSig, classTyVars ) +import TyCon ( TyCon, ArgVrcs, DataConDetails(..), + tyConDataCons, mkForeignTyCon, isProductTyCon, isRecursiveTyCon, + tyConTheta, getSynTyConDefn, tyConDataCons, isSynTyCon, tyConName ) +import DataCon ( DataCon, dataConWrapId, dataConName, dataConSig, dataConFieldLabels ) +import Var ( TyVar, idType, idName ) +import VarSet ( elemVarSet ) +import Name ( Name, getSrcLoc ) +import Outputable +import Util ( zipLazy, isSingleton, notNull ) +import SrcLoc ( srcLocSpan, Located(..), unLoc ) +import ListSetOps ( equivClasses ) +import CmdLineOpts ( DynFlag( Opt_GlasgowExts, Opt_Generics, Opt_UnboxStrictFields ) ) \end{code} -The main function -~~~~~~~~~~~~~~~~~ -\begin{code} -data Decl = TyD RenamedTyDecl | ClD RenamedClassDecl -tcTyAndClassDecls1 :: InstanceMapper - -> Bag RenamedTyDecl -> Bag RenamedClassDecl - -> TcM s (TcEnv s) +%************************************************************************ +%* * +\subsection{Type checking for type and class declarations} +%* * +%************************************************************************ -tcTyAndClassDecls1 inst_mapper rnty_decls rncls_decls - = sortByDependency syn_decls cls_decls decls `thenTc` \ groups -> - tcGroups inst_mapper groups - where - cls_decls = mapBag ClD rncls_decls - ty_decls = mapBag TyD rnty_decls - syn_decls = filterBag is_syn_decl ty_decls - decls = ty_decls `unionBags` cls_decls +Dealing with a group +~~~~~~~~~~~~~~~~~~~~ +Consider a mutually-recursive group, binding +a type constructor T and a class C. + +Step 1: getInitialKind + Construct a KindEnv by binding T and C to a kind variable + +Step 2: kcTyClDecl + In that environment, do a kind check + +Step 3: Zonk the kinds - is_syn_decl (TyD (TySynonym _ _ _ _)) = True - is_syn_decl _ = False +Step 4: buildTyConOrClass + Construct an environment binding T to a TyCon and C to a Class. + a) Their kinds comes from zonking the relevant kind variable + b) Their arity (for synonyms) comes direct from the decl + c) The funcional dependencies come from the decl + d) The rest comes a knot-tied binding of T and C, returned from Step 4 + e) The variances of the tycons in the group is calculated from + the knot-tied stuff -tcGroups inst_mapper [] - = tcGetEnv `thenNF_Tc` \ env -> - returnTc env +Step 5: tcTyClDecl1 + In this environment, walk over the decls, constructing the TyCons and Classes. + This uses in a strict way items (a)-(c) above, which is why they must + be constructed in Step 4. Feed the results back to Step 4. + For this step, pass the is-recursive flag as the wimp-out flag + to tcTyClDecl1. + -tcGroups inst_mapper (group:groups) - = tcGroup inst_mapper group `thenTc` \ new_env -> +Step 6: Extend environment + We extend the type environment with bindings not only for the TyCons and Classes, + but also for their "implicit Ids" like data constructors and class selectors - -- Extend the environment using the new tycons and classes - tcSetEnv new_env $ +Step 7: checkValidTyCl + For a recursive group only, check all the decls again, just + to check all the side conditions on validity. We could not + do this before because we were in a mutually recursive knot. - -- Do the remaining groups - tcGroups inst_mapper groups + +The knot-tying parameters: @rec_details_list@ is an alist mapping @Name@s to +@TyThing@s. @rec_vrcs@ is a finite map from @Name@s to @ArgVrcs@s. + +\begin{code} +tcTyAndClassDecls :: [LTyClDecl Name] + -> TcM TcGblEnv -- Input env extended by types and classes + -- and their implicit Ids,DataCons +tcTyAndClassDecls decls + = do { -- First check for cyclic type synonysm or classes + -- See notes with checkCycleErrs + checkCycleErrs decls + + ; let { udecls = map unLoc decls } + ; tyclss <- fixM (\ rec_tyclss -> + do { lcl_things <- mappM getInitialKind udecls + -- Extend the local env with kinds, and + -- the global env with the knot-tied results + ; let { gbl_things = mkGlobalThings udecls rec_tyclss } + ; tcExtendRecEnv gbl_things lcl_things $ do + + -- The local type environment is populated with + -- {"T" -> ARecTyCon k, ...} + -- and the global type envt with + -- {"T" -> ATyCon T, ...} + -- where k is T's (unzonked) kind + -- T is the loop-tied TyCon itself + -- We must populate the environment with the loop-tied T's right + -- away, because the kind checker may "fault in" some type + -- constructors that recursively mention T + + -- Kind-check the declarations, returning kind-annotated decls + { kc_decls <- mappM kcTyClDecl decls + + -- Calculate variances and rec-flag + ; let { calc_vrcs = calcTyConArgVrcs rec_tyclss + ; calc_rec = calcRecFlags rec_tyclss } + + ; mappM (tcTyClDecl calc_vrcs calc_rec) kc_decls + }}) + -- Finished with knot-tying now + -- Extend the environment with the finished things + ; tcExtendGlobalEnv tyclss $ do + + -- Perform the validity check + { traceTc (text "ready for validity check") + ; mappM_ checkValidTyCl decls + ; traceTc (text "done") + + -- Add the implicit things; + -- we want them in the environment because + -- they may be mentioned in interface files + ; let { implicit_things = concatMap implicitTyThings tyclss } + ; traceTc ((text "Adding" <+> ppr tyclss) $$ (text "and" <+> ppr implicit_things)) + ; tcExtendGlobalEnv implicit_things getGblEnv + }} + +mkGlobalThings :: [TyClDecl Name] -- The decls + -> [TyThing] -- Knot-tied, in 1-1 correspondence with the decls + -> [(Name,TyThing)] +-- Driven by the Decls, and treating the TyThings lazily +-- make a TypeEnv for the new things +mkGlobalThings decls things + = map mk_thing (decls `zipLazy` things) + where + mk_thing (ClassDecl {tcdLName = L _ name}, ~(AClass cl)) + = (name, AClass cl) + mk_thing (decl, ~(ATyCon tc)) + = (tcdName decl, ATyCon tc) \end{code} -Dealing with a group -~~~~~~~~~~~~~~~~~~~~ + +%************************************************************************ +%* * + Kind checking +%* * +%************************************************************************ + +We need to kind check all types in the mutually recursive group +before we know the kind of the type variables. For example: + +class C a where + op :: D b => a -> b -> b + +class D c where + bop :: (Monad c) => ... + +Here, the kind of the locally-polymorphic type variable "b" +depends on *all the uses of class D*. For example, the use of +Monad c in bop's type signature means that D must have kind Type->Type. + \begin{code} -tcGroup :: InstanceMapper -> Bag Decl -> TcM s (TcEnv s) -tcGroup inst_mapper decls - = -- pprTrace "tcGroup: " (ppCat (map (fst.fmt_decl) (bagToList decls))) $ +------------------------------------------------------------------------ +getInitialKind :: TyClDecl Name -> TcM (Name, TcTyThing) - -- TIE THE KNOT - fixTc ( \ ~(tycons,classes,_) -> +-- Note the lazy pattern match on the ATyCon etc +-- Exactly the same reason as the zipLay above - -- EXTEND TYPE AND CLASS ENVIRONMENTS - -- NB: it's important that the tycons and classes come back in just - -- the same order from this fix as from get_binders, so that these - -- extend-env things work properly. A bit UGH-ish. - tcExtendTyConEnv tycon_names_w_arities tycons $ - tcExtendClassEnv class_names classes $ +getInitialKind (TyData {tcdLName = L _ name}) + = newKindVar `thenM` \ kind -> + returnM (name, ARecTyCon kind) - -- DEAL WITH TYPE VARIABLES - tcTyVarScope tyvar_names ( \ tyvars -> +getInitialKind (TySynonym {tcdLName = L _ name}) + = newKindVar `thenM` \ kind -> + returnM (name, ARecTyCon kind) - -- DEAL WITH THE DEFINITIONS THEMSELVES - foldBag combine (tcDecl inst_mapper) - (returnTc (emptyBag, emptyBag)) - decls - ) `thenTc` \ (tycon_bag,class_bag) -> - let - tycons = bagToList tycon_bag - classes = bagToList class_bag - in +getInitialKind (ClassDecl {tcdLName = L _ name}) + = newKindVar `thenM` \ kind -> + returnM (name, ARecClass kind) - -- SNAFFLE ENV TO RETURN - tcGetEnv `thenNF_Tc` \ final_env -> - returnTc (tycons, classes, final_env) - ) `thenTc` \ (_, _, final_env) -> +------------------------------------------------------------------------ +kcTyClDecl :: LTyClDecl Name -> TcM (LTyClDecl Name) - returnTc final_env +kcTyClDecl decl@(L loc d@(TySynonym {tcdSynRhs = rhs})) + = do { res_kind <- newKindVar + ; kcTyClDeclBody decl res_kind $ \ tvs' -> + do { rhs' <- kcCheckHsType rhs res_kind + ; return (L loc d{tcdTyVars = tvs', tcdSynRhs = rhs'}) } } +kcTyClDecl decl@(L loc d@(TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdCons = cons})) + = kcTyClDeclBody decl liftedTypeKind $ \ tvs' -> + do { ctxt' <- kcHsContext ctxt + ; cons' <- mappM (wrapLocM kc_con_decl) cons + ; return (L loc d{tcdTyVars = tvs', tcdCtxt = ctxt', tcdCons = cons'}) } where - (tyvar_rn_names, tycon_names_w_arities, class_names) = get_binders decls + kc_con_decl (ConDecl name ex_tvs ex_ctxt details) + = kcHsTyVars ex_tvs $ \ ex_tvs' -> + do { ex_ctxt' <- kcHsContext ex_ctxt + ; details' <- kc_con_details details + ; return (ConDecl name ex_tvs' ex_ctxt' details')} + + kc_con_details (PrefixCon btys) + = do { btys' <- mappM kc_larg_ty btys ; return (PrefixCon btys') } + kc_con_details (InfixCon bty1 bty2) + = do { bty1' <- kc_larg_ty bty1; bty2' <- kc_larg_ty bty2; return (InfixCon bty1' bty2') } + kc_con_details (RecCon fields) + = do { fields' <- mappM kc_field fields; return (RecCon fields') } + + kc_field (fld, bty) = do { bty' <- kc_larg_ty bty ; return (fld, bty') } + + kc_larg_ty = wrapLocM kc_arg_ty + + kc_arg_ty (BangType str ty) = do { ty' <- kc_arg_ty_body ty; return (BangType str ty') } + kc_arg_ty_body = case new_or_data of + DataType -> kcHsSigType + NewType -> kcHsLiftedSigType + -- Can't allow an unlifted type for newtypes, because we're effectively + -- going to remove the constructor while coercing it to a lifted type. + +kcTyClDecl decl@(L loc d@(ClassDecl {tcdCtxt = ctxt, tcdSigs = sigs})) + = kcTyClDeclBody decl liftedTypeKind $ \ tvs' -> + do { ctxt' <- kcHsContext ctxt + ; sigs' <- mappM (wrapLocM kc_sig) sigs + ; return (L loc d{tcdTyVars = tvs', tcdCtxt = ctxt', tcdSigs = sigs'}) } + where + kc_sig (Sig nm op_ty) = do { op_ty' <- kcHsLiftedSigType op_ty + ; return (Sig nm op_ty') } + kc_sig other_sig = return other_sig + +kcTyClDecl decl@(L _ (ForeignType {})) + = return decl + +kcTyClDeclBody :: LTyClDecl Name -> TcKind + -> ([LHsTyVarBndr Name] -> TcM a) + -> TcM a + -- Extend the env with bindings for the tyvars, taken from + -- the kind of the tycon/class. Give it to the thing inside, and + -- check the result kind matches +kcTyClDeclBody decl res_kind thing_inside + = tcAddDeclCtxt decl $ + kcHsTyVars (tyClDeclTyVars (unLoc decl)) $ \ kinded_tvs -> + do { tc_ty_thing <- tcLookupLocated (tcdLName (unLoc decl)) + ; let { tc_kind = case tc_ty_thing of + ARecClass k -> k + ARecTyCon k -> k + } + ; unifyKind tc_kind (foldr (mkArrowKind . kindedTyVarKind) + res_kind kinded_tvs) + ; thing_inside kinded_tvs } + +kindedTyVarKind (L _ (KindedTyVar _ k)) = k +\end{code} - tyvar_names = map de_rn tyvar_rn_names - de_rn (RnName n) = n - combine do_a do_b - = do_a `thenTc` \ (a1,a2) -> - do_b `thenTc` \ (b1,b2) -> - returnTc (a1 `unionBags` b1, a2 `unionBags` b2) -\end{code} +%************************************************************************ +%* * +\subsection{Type checking} +%* * +%************************************************************************ -Dealing with one decl -~~~~~~~~~~~~~~~~~~~~~ \begin{code} -tcDecl :: InstanceMapper - -> Decl - -> TcM s (Bag TyCon, Bag Class) +tcTyClDecl :: (Name -> ArgVrcs) -> (Name -> RecFlag) + -> LTyClDecl Name -> TcM TyThing -tcDecl inst_mapper (TyD decl) - = tcTyDecl decl `thenTc` \ tycon -> - returnTc (unitBag tycon, emptyBag) +tcTyClDecl calc_vrcs calc_isrec decl + = tcAddDeclCtxt decl (tcTyClDecl1 calc_vrcs calc_isrec (unLoc decl)) -tcDecl inst_mapper (ClD decl) - = tcClassDecl1 inst_mapper decl `thenTc` \ clas -> - returnTc (emptyBag, unitBag clas) +tcTyClDecl1 calc_vrcs calc_isrec + (TySynonym {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdSynRhs = rhs_ty}) + = tcTyVarBndrs tvs $ \ tvs' -> do + { rhs_ty' <- tcHsKindedType rhs_ty + ; return (ATyCon (buildSynTyCon tc_name tvs' rhs_ty' arg_vrcs)) } + where + arg_vrcs = calc_vrcs tc_name + +tcTyClDecl1 calc_vrcs calc_isrec + (TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs, + tcdLName = L _ tc_name, tcdCons = cons}) + = tcTyVarBndrs tvs $ \ tvs' -> do + { ctxt' <- tcHsKindedContext ctxt + ; want_generic <- doptM Opt_Generics + ; tycon <- fixM (\ tycon -> do + { cons' <- mappM (addLocM (tcConDecl new_or_data tycon tvs' ctxt')) cons + ; buildAlgTyCon new_or_data tc_name tvs' ctxt' + (DataCons cons') arg_vrcs is_rec + (want_generic && canDoGenerics cons') + }) + ; return (ATyCon tycon) + } + where + arg_vrcs = calc_vrcs tc_name + is_rec = calc_isrec tc_name + +tcTyClDecl1 calc_vrcs calc_isrec + (ClassDecl {tcdLName = L _ class_name, tcdTyVars = tvs, + tcdCtxt = ctxt, tcdMeths = meths, + tcdFDs = fundeps, tcdSigs = sigs} ) + = tcTyVarBndrs tvs $ \ tvs' -> do + { ctxt' <- tcHsKindedContext ctxt + ; fds' <- mappM (addLocM tc_fundep) fundeps + ; sig_stuff <- tcClassSigs class_name sigs meths + ; clas <- fixM (\ clas -> + let -- This little knot is just so we can get + -- hold of the name of the class TyCon, which we + -- need to look up its recursiveness and variance + tycon_name = tyConName (classTyCon clas) + tc_isrec = calc_isrec tycon_name + tc_vrcs = calc_vrcs tycon_name + in + buildClass class_name tvs' ctxt' fds' + sig_stuff tc_isrec tc_vrcs) + ; return (AClass clas) } + where + tc_fundep (tvs1, tvs2) = do { tvs1' <- mappM tcLookupTyVar tvs1 ; + ; tvs2' <- mappM tcLookupTyVar tvs2 ; + ; return (tvs1', tvs2') } + + +tcTyClDecl1 calc_vrcs calc_isrec + (ForeignType {tcdLName = L _ tc_name, tcdExtName = tc_ext_name}) + = returnM (ATyCon (mkForeignTyCon tc_name tc_ext_name liftedTypeKind 0 [])) + +----------------------------------- +tcConDecl :: NewOrData -> TyCon -> [TyVar] -> ThetaType + -> ConDecl Name -> TcM DataCon + +tcConDecl new_or_data tycon tyvars ctxt + (ConDecl name ex_tvs ex_ctxt details) + = tcTyVarBndrs ex_tvs $ \ ex_tvs' -> do + { ex_ctxt' <- tcHsKindedContext ex_ctxt + ; unbox_strict <- doptM Opt_UnboxStrictFields + ; let + tc_datacon field_lbls btys + = do { let { ubtys = map unLoc btys } + ; arg_tys <- mappM (tcHsKindedType . getBangType) ubtys + ; buildDataCon (unLoc name) + (argStrictness unbox_strict tycon ubtys arg_tys) + (map unLoc field_lbls) + tyvars ctxt ex_tvs' ex_ctxt' + arg_tys tycon } + ; case details of + PrefixCon btys -> tc_datacon [] btys + InfixCon bty1 bty2 -> tc_datacon [] [bty1,bty2] + RecCon fields -> do { checkTc (null ex_tvs') (exRecConErr name) + ; let { (field_names, btys) = unzip fields } + ; tc_datacon field_names btys } } + +argStrictness :: Bool -- True <=> -funbox-strict_fields + -> TyCon -> [BangType Name] + -> [TcType] -> [StrictnessMark] +argStrictness unbox_strict tycon btys arg_tys + = zipWith (chooseBoxingStrategy unbox_strict tycon) + arg_tys + (map getBangStrictness btys ++ repeat HsNoBang) + +-- We attempt to unbox/unpack a strict field when either: +-- (i) The field is marked '!!', or +-- (ii) The field is marked '!', and the -funbox-strict-fields flag is on. + +chooseBoxingStrategy :: Bool -> TyCon -> TcType -> HsBang -> StrictnessMark +chooseBoxingStrategy unbox_strict_fields tycon arg_ty bang + = case bang of + HsNoBang -> NotMarkedStrict + HsStrict | unbox_strict_fields && can_unbox -> MarkedUnboxed + HsUnbox | can_unbox -> MarkedUnboxed + other -> MarkedStrict + where + can_unbox = case splitTyConApp_maybe arg_ty of + Nothing -> False + Just (arg_tycon, _) -> not (isRecursiveTyCon tycon) && + isProductTyCon arg_tycon \end{code} -Dependency analysis -~~~~~~~~~~~~~~~~~~~ +%************************************************************************ +%* * +\subsection{Dependency analysis} +%* * +%************************************************************************ + +Validity checking is done once the mutually-recursive knot has been +tied, so we can look at things freely. + \begin{code} -sortByDependency :: Bag Decl -> Bag Decl -> Bag Decl -> TcM s [Bag Decl] -sortByDependency syn_decls cls_decls decls - = let -- CHECK FOR SYNONYM CYCLES - syn_sccs = findSCCs mk_edges syn_decls - syn_cycles = [map fmt_decl (bagToList decls) - | CyclicSCC decls <- syn_sccs] - - in - checkTc (null syn_cycles) (typeCycleErr syn_cycles) `thenTc_` - - let -- CHECK FOR CLASS CYCLES - cls_sccs = findSCCs mk_edges cls_decls - cls_cycles = [map fmt_decl (bagToList decls) - | CyclicSCC decls <- cls_sccs] - - in - checkTc (null cls_cycles) (classCycleErr cls_cycles) `thenTc_` - - -- DO THE MAIN DEPENDENCY ANALYSIS - let - decl_sccs = findSCCs mk_edges decls - scc_bags = map bag_acyclic decl_sccs - in - returnTc (scc_bags) - +checkCycleErrs :: [LTyClDecl Name] -> TcM () +checkCycleErrs tyclss + | null syn_cycles && null cls_cycles + = return () + | otherwise + = do { mappM_ recSynErr syn_cycles + ; mappM_ recClsErr cls_cycles + ; failM } -- Give up now, because later checkValidTyCl + -- will loop if the synonym is recursive where - bag_acyclic (AcyclicSCC scc) = unitBag scc - bag_acyclic (CyclicSCC sccs) = sccs + (syn_cycles, cls_cycles) = calcCycleErrs tyclss + +checkValidTyCl :: LTyClDecl Name -> TcM () +-- We do the validity check over declarations, rather than TyThings +-- only so that we can add a nice context with tcAddDeclCtxt +checkValidTyCl decl + = tcAddDeclCtxt decl $ + do { thing <- tcLookupLocatedGlobal (tcdLName (unLoc decl)) + ; traceTc (text "Validity of" <+> ppr thing) + ; case thing of + ATyCon tc -> checkValidTyCon tc + AClass cl -> checkValidClass cl + ; traceTc (text "Done validity of" <+> ppr thing) + } + +------------------------- +checkValidTyCon :: TyCon -> TcM () +checkValidTyCon tc + | isSynTyCon tc + = checkValidType syn_ctxt syn_rhs + | otherwise + = -- Check the context on the data decl + checkValidTheta (DataTyCtxt name) (tyConTheta tc) `thenM_` + + -- Check arg types of data constructors + mappM_ checkValidDataCon data_cons `thenM_` + + -- Check that fields with the same name share a type + mappM_ check_fields groups -fmt_decl decl - = (ppr PprForUser name, getSrcLoc name) where - name = get_name decl - get_name (TyD (TyData _ name _ _ _ _ _)) = name - get_name (TyD (TyNew _ name _ _ _ _ _)) = name - get_name (TyD (TySynonym name _ _ _)) = name - get_name (ClD (ClassDecl _ name _ _ _ _ _)) = name -\end{code} - -Edges in Type/Class decls -~~~~~~~~~~~~~~~~~~~~~~~~~ -\begin{code} -mk_edges (TyD (TyData ctxt name _ condecls derivs _ _)) - = (uniqueOf name, set_to_bag (get_ctxt ctxt `unionUniqSets` get_cons condecls `unionUniqSets` get_deriv derivs)) -mk_edges (TyD (TyNew ctxt name _ condecl derivs _ _)) - = (uniqueOf name, set_to_bag (get_ctxt ctxt `unionUniqSets` get_cons condecl `unionUniqSets` get_deriv derivs)) -mk_edges (TyD (TySynonym name _ rhs _)) - = (uniqueOf name, set_to_bag (get_ty rhs)) -mk_edges (ClD (ClassDecl ctxt name _ sigs _ _ _)) - = (uniqueOf name, set_to_bag (get_ctxt ctxt `unionUniqSets` get_sigs sigs)) - -get_ctxt ctxt - = unionManyUniqSets (map (set_name.fst) ctxt) - -get_deriv Nothing = emptyUniqSet -get_deriv (Just clss) = unionManyUniqSets (map set_name clss) - -get_cons cons - = unionManyUniqSets (map get_con cons) + syn_ctxt = TySynCtxt name + name = tyConName tc + (_, syn_rhs) = getSynTyConDefn tc + data_cons = tyConDataCons tc + + fields = [field | con <- data_cons, field <- dataConFieldLabels con] + groups = equivClasses cmp_name fields + cmp_name field1 field2 = fieldLabelName field1 `compare` fieldLabelName field2 + + check_fields fields@(first_field_label : other_fields) + -- These fields all have the same name, but are from + -- different constructors in the data type + = -- Check that all the fields in the group have the same type + -- NB: this check assumes that all the constructors of a given + -- data type use the same type variables + checkTc (all (tcEqType field_ty) other_tys) (fieldTypeMisMatch field_name) + where + field_ty = fieldLabelType first_field_label + field_name = fieldLabelName first_field_label + other_tys = map fieldLabelType other_fields + +------------------------------- +checkValidDataCon :: DataCon -> TcM () +checkValidDataCon con + = addErrCtxt (dataConCtxt con) ( + checkValidType ctxt (idType (dataConWrapId con)) `thenM_` + -- This checks the argument types and + -- ambiguity of the existential context (if any) + checkFreeness ex_tvs ex_theta) where - get_con (ConDecl _ btys _) - = unionManyUniqSets (map get_bty btys) - get_con (ConOpDecl bty1 _ bty2 _) - = unionUniqSets (get_bty bty1) (get_bty bty2) - get_con (NewConDecl _ ty _) - = get_ty ty - get_con (RecConDecl _ nbtys _) - = unionManyUniqSets (map (get_bty.snd) nbtys) - - get_bty (Banged ty) = get_pty ty - get_bty (Unbanged ty) = get_pty ty - -get_ty (MonoTyVar tv) - = emptyUniqSet -get_ty (MonoTyApp name tys) - = (if isRnTyCon name then set_name name else emptyUniqSet) - `unionUniqSets` get_tys tys -get_ty (MonoFunTy ty1 ty2) - = unionUniqSets (get_ty ty1) (get_ty ty2) -get_ty (MonoListTy ty) - = get_ty ty -- careful when defining [] (,,) etc as -get_ty (MonoTupleTy tys) -- [ty] (ty,ty,ty) will not give edges! - = get_tys tys -get_ty other = panic "TcTyClsDecls:get_ty" - -get_pty (HsForAllTy _ ctxt mty) - = get_ctxt ctxt `unionUniqSets` get_ty mty -get_pty other = panic "TcTyClsDecls:get_pty" - -get_tys tys - = unionManyUniqSets (map get_ty tys) - -get_sigs sigs - = unionManyUniqSets (map get_sig sigs) - where - get_sig (ClassOpSig _ ty _ _) = get_pty ty - get_sig other = panic "TcTyClsDecls:get_sig" - -set_name name = unitUniqSet (uniqueOf name) - -set_to_bag set = listToBag (uniqSetToList set) -\end{code} + ctxt = ConArgCtxt (dataConName con) + (_, _, ex_tvs, ex_theta, _, _) = dataConSig con -get_binders -~~~~~~~~~~~ -Extract *binding* names from type and class decls. Type variables are -bound in type, data, newtype and class declarations and the polytypes -in the class op sigs. +------------------------------- +checkValidClass :: Class -> TcM () +checkValidClass cls + = do { -- CHECK ARITY 1 FOR HASKELL 1.4 + gla_exts <- doptM Opt_GlasgowExts -Why do we need to grab all these type variables at once, including -those locally-quantified type variables in class op signatures? -Because we can only commit to the final kind of a type variable when -we've completed the mutually recursive group. For example: + -- Check that the class is unary, unless GlaExs + ; checkTc (notNull tyvars) (nullaryClassErr cls) + ; checkTc (gla_exts || unary) (classArityErr cls) -class C a where - op :: D b => a -> b -> b + -- Check the super-classes + ; checkValidTheta (ClassSCCtxt (className cls)) theta -class D c where - bop :: (Monad c) => ... + -- Check the class operations + ; mappM_ check_op op_stuff -Here, the kind of the locally-polymorphic type variable "b" -depends on *all the uses of class D*. For example, the use of -Monad c in bop's type signature means that D must have kind Type->Type. + -- 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 cls) + } + where + (tyvars, theta, _, op_stuff) = classBigSig cls + unary = isSingleton tyvars + no_generics = null [() | (_, GenDefMeth) <- op_stuff] + check_op (sel_id, dm) + = addErrCtxt (classOpCtxt sel_id tau) $ do + { checkValidTheta SigmaCtxt (tail theta) + -- The 'tail' removes the initial (C a) from the + -- class itself, leaving just the method type -\begin{code} -get_binders :: Bag Decl - -> ([RnName], -- TyVars; no dups - [(RnName, Maybe Arity)],-- Tycons; no dups; arities for synonyms - [RnName]) -- Classes; no dups + ; checkValidType (FunSigCtxt op_name) tau -get_binders decls = (bagToList tyvars, bagToList tycons, bagToList classes) - where - (tyvars, tycons, classes) = foldBag union3 get_binders1 - (emptyBag,emptyBag,emptyBag) - decls - - union3 (a1,a2,a3) (b1,b2,b3) - = (a1 `unionBags` b1, a2 `unionBags` b2, a3 `unionBags` b3) - -get_binders1 (TyD (TyData _ name tyvars _ _ _ _)) - = (listToBag tyvars, unitBag (name,Nothing), emptyBag) -get_binders1 (TyD (TyNew _ name tyvars _ _ _ _)) - = (listToBag tyvars, unitBag (name,Nothing), emptyBag) -get_binders1 (TyD (TySynonym name tyvars _ _)) - = (listToBag tyvars, unitBag (name, Just (length tyvars)), emptyBag) -get_binders1 (ClD (ClassDecl _ name tyvar sigs _ _ _)) - = (unitBag tyvar `unionBags` sigs_tvs sigs, - emptyBag, unitBag name) - -sigs_tvs sigs = unionManyBags (map sig_tvs sigs) - where - sig_tvs (ClassOpSig _ ty _ _) = pty_tvs ty - pty_tvs (HsForAllTy tvs _ _) = listToBag tvs -- tvs doesn't include the class tyvar -\end{code} + -- Check that the type mentions at least one of + -- the class type variables + ; checkTc (any (`elemVarSet` tyVarsOfType tau) tyvars) + (noClassTyVarErr cls sel_id) + + -- Check that for a generic method, the type of + -- the method is sufficiently simple + ; checkTc (dm /= GenDefMeth || validGenericMethodType op_ty) + (badGenericMethodType op_name op_ty) + } + where + op_name = idName sel_id + op_ty = idType sel_id + (_,theta,tau) = tcSplitSigmaTy op_ty -\begin{code} -typeCycleErr syn_cycles sty - = ppAboves (map (pp_cycle sty "Cycle in type declarations ...") syn_cycles) -classCycleErr cls_cycles sty - = ppAboves (map (pp_cycle sty "Cycle in class declarations ...") cls_cycles) +--------------------------------------------------------------------- +fieldTypeMisMatch field_name + = sep [ptext SLIT("Different constructors give different types for field"), quotes (ppr field_name)] -pp_cycle sty str things - = ppHang (ppStr str) - 4 (ppAboves (map pp_thing things)) +dataConCtxt con = sep [ptext SLIT("When checking the data constructor:"), + nest 2 (ex_part <+> pprThetaArrow ex_theta <+> ppr con <+> arg_part)] where - pp_thing (pp_name, loc) - = ppCat [pp_name, ppr sty loc] + (_, _, ex_tvs, ex_theta, arg_tys, _) = dataConSig con + ex_part | null ex_tvs = empty + | otherwise = ptext SLIT("forall") <+> hsep (map ppr ex_tvs) <> dot + -- The 'ex_theta' part could be non-empty, if the user (bogusly) wrote + -- data T a = Eq a => T a a + -- So we make sure to print it + + fields = dataConFieldLabels con + arg_part | null fields = sep (map pprParendType arg_tys) + | otherwise = braces (sep (punctuate comma + [ ppr n <+> dcolon <+> ppr ty + | (n,ty) <- fields `zip` arg_tys])) + +classOpCtxt sel_id tau = sep [ptext SLIT("When checking the class method:"), + nest 2 (ppr sel_id <+> dcolon <+> ppr tau)] + +nullaryClassErr cls + = ptext SLIT("No parameters for class") <+> quotes (ppr cls) + +classArityErr cls + = vcat [ptext SLIT("Too many parameters for class") <+> quotes (ppr cls), + parens (ptext SLIT("Use -fglasgow-exts to allow multi-parameter classes"))] + +noClassTyVarErr clas op + = sep [ptext SLIT("The class method") <+> quotes (ppr op), + ptext SLIT("mentions none of the type variables of the class") <+> + ppr clas <+> hsep (map ppr (classTyVars clas))] + +genericMultiParamErr clas + = ptext SLIT("The multi-parameter class") <+> quotes (ppr clas) <+> + ptext SLIT("cannot have generic methods") + +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")]) + +recSynErr tcs + = addSrcSpan (srcLocSpan (getSrcLoc (head tcs))) $ + addErr (sep [ptext SLIT("Cycle in type synonym declarations:"), + nest 2 (vcat (map ppr_thing tcs))]) + +recClsErr clss + = addSrcSpan (srcLocSpan (getSrcLoc (head clss))) $ + addErr (sep [ptext SLIT("Cycle in class declarations (via superclasses):"), + nest 2 (vcat (map ppr_thing clss))]) + +ppr_thing :: Name -> SDoc +ppr_thing n = ppr n <+> parens (ppr (getSrcLoc n)) + + +exRecConErr name + = ptext SLIT("Can't combine named fields with locally-quantified type variables") + $$ + (ptext SLIT("In the declaration of data constructor") <+> ppr name) \end{code}