X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcTyClsDecls.lhs;h=95166861ec668c6e0a09546ffc9f5e52a645de73;hb=6a4854eaa266d994ebd0d471614a52b43dd329d9;hp=284946fa55fa55341e588fe3a5e5fedf3807a760;hpb=1fb1ab5d53a09607e7f6d2450806760688396387;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcTyClsDecls.lhs b/ghc/compiler/typecheck/TcTyClsDecls.lhs index 284946f..9516686 100644 --- a/ghc/compiler/typecheck/TcTyClsDecls.lhs +++ b/ghc/compiler/typecheck/TcTyClsDecls.lhs @@ -1,328 +1,740 @@ % -% (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 -IMP_Ubiq(){-uitous-} +#include "HsVersions.h" -import HsSyn ( HsDecl(..), TyDecl(..), ConDecl(..), BangType(..), - ClassDecl(..), HsType(..), HsTyVar, DefaultDecl, InstDecl, - IfaceSig, Sig(..), MonoBinds, Fake, InPat, HsBinds(..), Bind, HsExpr, - hsDeclName - ) -import RnHsSyn ( RenamedTyDecl(..), RenamedClassDecl(..), SYN_IE(RenamedHsDecl) +import HsSyn ( TyClDecl(..), HsConDetails(..), HsTyVarBndr(..), + ConDecl(..), Sig(..), , NewOrData(..), + tyClDeclTyVars, isSynDecl, LConDecl, + LTyClDecl, tcdName, LHsTyVarBndr, LHsContext ) -import TcHsSyn ( SYN_IE(TcHsBinds), TcIdOcc(..) ) - -import TcMonad -import Inst ( SYN_IE(InstanceMapper) ) -import TcClassDcl ( tcClassDecl1 ) -import TcEnv ( tcExtendTyConEnv, tcExtendClassEnv ) -import SpecEnv ( SpecEnv ) -import TcKind ( TcKind, newKindVars ) -import TcTyDecls ( tcTyDecl, mkDataBinds ) -import TcMonoType ( tcTyVarScope ) - -import Bag -import Class ( SYN_IE(Class), classSelIds ) -import Digraph ( findSCCs, SCC(..) ) -import Name ( Name, getSrcLoc, isTvOcc, nameOccName ) -import PprStyle -import Pretty -import UniqSet ( SYN_IE(UniqSet), emptyUniqSet, - unitUniqSet, unionUniqSets, - unionManyUniqSets, uniqSetToList ) -import SrcLoc ( SrcLoc ) -import TyCon ( TyCon ) -import Unique ( Unique ) -import Util ( panic{-, pprTrace-} ) - +import HsTypes ( HsBang(..), getBangStrictness ) +import BasicTypes ( RecFlag(..), StrictnessMark(..) ) +import HscTypes ( implicitTyThings ) +import BuildTyCl ( buildClass, buildAlgTyCon, buildSynTyCon, buildDataCon, + mkDataTyConRhs, mkNewTyConRhs ) +import TcRnMonad +import TcEnv ( TcTyThing(..), TyThing(..), + tcLookupLocated, tcLookupLocatedGlobal, + tcExtendGlobalEnv, tcExtendKindEnv, + tcExtendRecEnv, tcLookupTyVar ) +import TcTyDecls ( calcTyConArgVrcs, calcRecFlags, calcClassCycles, calcSynCycles ) +import TcClassDcl ( tcClassSigs, tcAddDeclCtxt ) +import TcHsType ( kcHsTyVars, kcHsLiftedSigType, kcHsType, + kcHsContext, tcTyVarBndrs, tcHsKindedType, tcHsKindedContext, + kcHsSigType, tcHsBangType, tcLHsConSig ) +import TcMType ( newKindVar, checkValidTheta, checkValidType, checkFreeness, + UserTypeCtxt(..), SourceTyCtxt(..) ) +import TcUnify ( unifyKind ) +import TcType ( TcKind, ThetaType, TcType, tyVarsOfType, + mkArrowKind, liftedTypeKind, mkTyVarTys, tcEqTypes, + tcSplitSigmaTy, tcEqType ) +import Type ( splitTyConApp_maybe, pprThetaArrow, pprParendType ) +import Generics ( validGenericMethodType, canDoGenerics ) +import Class ( Class, className, classTyCon, DefMeth(..), classBigSig, classTyVars ) +import TyCon ( TyCon, ArgVrcs, + tyConDataCons, mkForeignTyCon, isProductTyCon, isRecursiveTyCon, + tyConStupidTheta, getSynTyConDefn, tyConDataCons, isSynTyCon, tyConName ) +import DataCon ( DataCon, dataConWrapId, dataConName, dataConSig, + dataConFieldLabels, dataConOrigArgTys, dataConTyCon ) +import Type ( zipTopTvSubst, substTys ) +import Var ( TyVar, idType, idName ) +import VarSet ( elemVarSet ) +import Name ( Name ) +import Outputable +import Util ( zipLazy, isSingleton, notNull, sortLe ) +import List ( partition ) +import SrcLoc ( Located(..), unLoc, getLoc ) +import ListSetOps ( equivClasses ) +import Digraph ( SCC(..) ) +import CmdLineOpts ( DynFlag( Opt_GlasgowExts, Opt_Generics, Opt_UnboxStrictFields ) ) \end{code} -The main function -~~~~~~~~~~~~~~~~~ -\begin{code} -tcTyAndClassDecls1 :: InstanceMapper - -> [RenamedHsDecl] - -> TcM s (TcEnv s) -tcTyAndClassDecls1 inst_mapper decls - = sortByDependency decls `thenTc` \ groups -> - tcGroups inst_mapper groups +%************************************************************************ +%* * +\subsection{Type checking for type and class declarations} +%* * +%************************************************************************ + +Dealing with a group +~~~~~~~~~~~~~~~~~~~~ +Consider a mutually-recursive group, binding +a type constructor T and a class C. -tcGroups inst_mapper [] - = tcGetEnv `thenNF_Tc` \ env -> - returnTc env +Step 1: getInitialKind + Construct a KindEnv by binding T and C to a kind variable -tcGroups inst_mapper (group:groups) - = tcGroup inst_mapper group `thenTc` \ new_env -> +Step 2: kcTyClDecl + In that environment, do a kind check - -- Extend the environment using the new tycons and classes - tcSetEnv new_env $ +Step 3: Zonk the kinds - -- Do the remaining groups - tcGroups inst_mapper groups -\end{code} +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 + +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. + + +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 + +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. + + +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. -Dealing with a group -~~~~~~~~~~~~~~~~~~~~ \begin{code} -tcGroup :: InstanceMapper -> Bag RenamedHsDecl -> TcM s (TcEnv s) -tcGroup inst_mapper decls - = -- pprTrace "tcGroup: " (ppCat (map (fst.fmt_decl) (bagToList decls))) $ +tcTyAndClassDecls :: [Name] -> [LTyClDecl Name] + -> TcM TcGblEnv -- Input env extended by types and classes + -- and their implicit Ids,DataCons +tcTyAndClassDecls boot_names decls + = do { -- First check for cyclic type synonysm or classes + -- See notes with checkCycleErrs + checkCycleErrs decls + ; mod <- getModule + ; traceTc (text "tcTyAndCl" <+> ppr mod <+> ppr boot_names) + ; (syn_tycons, alg_tyclss) <- fixM (\ ~(rec_syn_tycons, rec_alg_tyclss) -> + do { let { -- Calculate variances and rec-flag + ; (syn_decls, alg_decls) = partition (isSynDecl . unLoc) decls } + + -- Extend the global env with the knot-tied results + -- for data types and classes + -- + -- 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 + ; let { gbl_things = mkGlobalThings alg_decls rec_alg_tyclss } + ; tcExtendRecEnv gbl_things $ do + + -- Kind-check the declarations + { (kc_syn_decls, kc_alg_decls) <- kcTyClDecls syn_decls alg_decls + + ; let { calc_vrcs = calcTyConArgVrcs (rec_syn_tycons ++ rec_alg_tyclss) + ; calc_rec = calcRecFlags boot_names rec_alg_tyclss + ; tc_decl = addLocM (tcTyClDecl calc_vrcs calc_rec) } + -- Type-check the type synonyms, and extend the envt + ; syn_tycons <- tcSynDecls calc_vrcs kc_syn_decls + ; tcExtendGlobalEnv syn_tycons $ do + + -- Type-check the data types and classes + { alg_tyclss <- mappM tc_decl kc_alg_decls + ; return (syn_tycons, alg_tyclss) + }}}) + -- Finished with knot-tying now + -- Extend the environment with the finished things + ; tcExtendGlobalEnv (syn_tycons ++ alg_tyclss) $ do + + -- Perform the validity check + { traceTc (text "ready for validity check") + ; mappM_ (addLocM 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 alg_tyclss } + ; traceTc ((text "Adding" <+> ppr alg_tyclss) $$ (text "and" <+> ppr implicit_things)) + ; tcExtendGlobalEnv implicit_things getGblEnv + }} + +mkGlobalThings :: [LTyClDecl 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 (L _ (ClassDecl {tcdLName = L _ name}), ~(AClass cl)) + = (name, AClass cl) + mk_thing (L _ decl, ~(ATyCon tc)) + = (tcdName decl, ATyCon tc) +\end{code} - -- TIE THE KNOT - fixTc ( \ ~(tycons,classes,_) -> - -- 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 $ +%************************************************************************ +%* * + Kind checking +%* * +%************************************************************************ - -- DEAL WITH TYPE VARIABLES - tcTyVarScope tyvar_names ( \ tyvars -> +We need to kind check all types in the mutually recursive group +before we know the kind of the type variables. For example: - -- 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 +class C a where + op :: D b => a -> b -> b - -- SNAFFLE ENV TO RETURN - tcGetEnv `thenNF_Tc` \ final_env -> +class D c where + bop :: (Monad c) => ... - returnTc (tycons, classes, final_env) - ) `thenTc` \ (_, _, final_env) -> +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. - returnTc final_env +However type synonyms work differently. They can have kinds which don't +just involve (->) and *: + type R = Int# -- Kind # + type S a = Array# a -- Kind * -> # + type T a b = (# a,b #) -- Kind * -> * -> (# a,b #) +So we must infer their kinds from their right-hand sides *first* and then +use them, whereas for the mutually recursive data types D we bring into +scope kind bindings D -> k, where k is a kind variable, and do inference. +\begin{code} +kcTyClDecls syn_decls alg_decls + = do { -- First extend the kind env with each data + -- type and class, mapping them to a type variable + alg_kinds <- mappM getInitialKind alg_decls + ; tcExtendKindEnv alg_kinds $ do + + -- Now kind-check the type synonyms, in dependency order + -- We do these differently to data type and classes, + -- because a type synonym can be an unboxed type + -- type Foo = Int# + -- and a kind variable can't unify with UnboxedTypeKind + -- So we infer their kinds in dependency order + { (kc_syn_decls, syn_kinds) <- kcSynDecls (calcSynCycles syn_decls) + ; tcExtendKindEnv syn_kinds $ do + + -- Now kind-check the data type and class declarations, + -- returning kind-annotated decls + { kc_alg_decls <- mappM (wrapLocM kcTyClDecl) alg_decls + + ; return (kc_syn_decls, kc_alg_decls) }}} + +------------------------------------------------------------------------ +getInitialKind :: LTyClDecl Name -> TcM (Name, TcKind) + +getInitialKind decl + = newKindVar `thenM` \ kind -> + returnM (unLoc (tcdLName (unLoc decl)), kind) + +---------------- +kcSynDecls :: [SCC (LTyClDecl Name)] + -> TcM ([LTyClDecl Name], -- Kind-annotated decls + [(Name,TcKind)]) -- Kind bindings +kcSynDecls [] + = return ([], []) +kcSynDecls (group : groups) + = do { (decl, nk) <- kcSynDecl group + ; (decls, nks) <- tcExtendKindEnv [nk] (kcSynDecls groups) + ; return (decl:decls, nk:nks) } + +---------------- +kcSynDecl :: SCC (LTyClDecl Name) + -> TcM (LTyClDecl Name, -- Kind-annotated decls + (Name,TcKind)) -- Kind bindings +kcSynDecl (AcyclicSCC ldecl@(L loc decl)) + = tcAddDeclCtxt decl $ + kcHsTyVars (tcdTyVars decl) (\ k_tvs -> + do { traceTc (text "kcd1" <+> ppr (unLoc (tcdLName decl)) <+> brackets (ppr (tcdTyVars decl)) + <+> brackets (ppr k_tvs)) + ; (k_rhs, rhs_kind) <- kcHsType (tcdSynRhs decl) + ; traceTc (text "kcd2" <+> ppr (unLoc (tcdLName decl))) + ; let tc_kind = foldr (mkArrowKind . kindedTyVarKind) rhs_kind k_tvs + ; return (L loc (decl { tcdTyVars = k_tvs, tcdSynRhs = k_rhs }), + (unLoc (tcdLName decl), tc_kind)) }) + +kcSynDecl (CyclicSCC decls) + = do { recSynErr decls; failM } -- Fail here to avoid error cascade + -- of out-of-scope tycons + +------------------------------------------------------------------------ +kcTyClDecl :: TyClDecl Name -> TcM (TyClDecl Name) + -- Not used for type synonyms (see kcSynDecl) + +kcTyClDecl decl@(TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdCons = cons}) + = kcTyClDeclBody decl $ \ tvs' -> + do { ctxt' <- kcHsContext ctxt + ; cons' <- mappM (wrapLocM kc_con_decl) cons + ; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdCons = cons'}) } + where + 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_decl (GadtDecl name ty) + = do { ty' <- kcHsSigType ty + ; return (GadtDecl name ty') } + + 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 bty = case new_or_data of + DataType -> kcHsSigType bty + NewType -> kcHsLiftedSigType bty + -- Can't allow an unlifted type for newtypes, because we're effectively + -- going to remove the constructor while coercing it to a lifted type. + -- And newtypes can't be bang'd + +kcTyClDecl decl@(ClassDecl {tcdCtxt = ctxt, tcdSigs = sigs}) + = kcTyClDeclBody decl $ \ tvs' -> + do { ctxt' <- kcHsContext ctxt + ; sigs' <- mappM (wrapLocM kc_sig) sigs + ; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdSigs = sigs'}) } where - (tyvar_names, tycon_names_w_arities, class_names) = get_binders decls + 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@(ForeignType {}) + = return decl + +kcTyClDeclBody :: TyClDecl Name + -> ([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 thing_inside + = tcAddDeclCtxt decl $ + kcHsTyVars (tyClDeclTyVars decl) $ \ kinded_tvs -> + do { tc_ty_thing <- tcLookupLocated (tcdLName decl) + ; let tc_kind = case tc_ty_thing of { AThing k -> k } + ; unifyKind tc_kind (foldr (mkArrowKind . kindedTyVarKind) + (result_kind decl) + kinded_tvs) + ; thing_inside kinded_tvs } + where + result_kind (TyData { tcdKindSig = Just kind }) = kind + result_kind other = liftedTypeKind + -- On GADT-style declarations we allow a kind signature + -- data T :: *->* where { ... } - combine do_a do_b - = do_a `thenTc` \ (a1,a2) -> - do_b `thenTc` \ (b1,b2) -> - returnTc (a1 `unionBags` b1, a2 `unionBags` b2) +kindedTyVarKind (L _ (KindedTyVar _ k)) = k \end{code} -Dealing with one decl -~~~~~~~~~~~~~~~~~~~~~ -\begin{code} -tcDecl :: InstanceMapper - -> RenamedHsDecl - -> TcM s (Bag TyCon, Bag Class) -tcDecl inst_mapper (TyD decl) - = tcTyDecl decl `thenTc` \ tycon -> - returnTc (unitBag tycon, emptyBag) +%************************************************************************ +%* * +\subsection{Type checking} +%* * +%************************************************************************ -tcDecl inst_mapper (ClD decl) - = tcClassDecl1 inst_mapper decl `thenTc` \ clas -> - returnTc (emptyBag, unitBag clas) +\begin{code} +tcSynDecls :: (Name -> ArgVrcs) -> [LTyClDecl Name] -> TcM [TyThing] +tcSynDecls calc_vrcs [] = return [] +tcSynDecls calc_vrcs (decl : decls) + = do { syn_tc <- addLocM (tcSynDecl calc_vrcs) decl + ; syn_tcs <- tcExtendGlobalEnv [syn_tc] (tcSynDecls calc_vrcs decls) + ; return (syn_tc : syn_tcs) } + +tcSynDecl calc_vrcs + (TySynonym {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdSynRhs = rhs_ty}) + = tcTyVarBndrs tvs $ \ tvs' -> do + { traceTc (text "tcd1" <+> ppr tc_name) + ; rhs_ty' <- tcHsKindedType rhs_ty + ; return (ATyCon (buildSynTyCon tc_name tvs' rhs_ty' (calc_vrcs tc_name))) } + +-------------------- +tcTyClDecl :: (Name -> ArgVrcs) -> (Name -> RecFlag) + -> TyClDecl Name -> TcM TyThing + +tcTyClDecl calc_vrcs calc_isrec decl + = tcAddDeclCtxt decl (tcTyClDecl1 calc_vrcs calc_isrec decl) + +tcTyClDecl1 calc_vrcs calc_isrec + (TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs, + tcdLName = L _ tc_name, tcdCons = cons}) + = tcTyVarBndrs tvs $ \ tvs' -> do + { stupid_theta <- tcStupidTheta ctxt cons + ; want_generic <- doptM Opt_Generics + ; tycon <- fixM (\ tycon -> do + { unbox_strict <- doptM Opt_UnboxStrictFields + ; gla_exts <- doptM Opt_GlasgowExts + ; checkTc (gla_exts || h98_syntax) (badGadtDecl tc_name) + + ; data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data tycon tvs')) cons + ; let tc_rhs = case new_or_data of + DataType -> mkDataTyConRhs stupid_theta data_cons + NewType -> ASSERT( isSingleton data_cons ) + mkNewTyConRhs tycon (head data_cons) + ; buildAlgTyCon tc_name tvs' tc_rhs arg_vrcs is_rec + (want_generic && canDoGenerics data_cons) + }) + ; return (ATyCon tycon) + } + where + arg_vrcs = calc_vrcs tc_name + is_rec = calc_isrec tc_name + h98_syntax = case cons of -- All constructors have same shape + L _ (GadtDecl {}) : _ -> False + other -> True + +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 :: Bool -- True <=> -funbox-strict_fields + -> NewOrData -> TyCon -> [TyVar] + -> ConDecl Name -> TcM DataCon + +tcConDecl unbox_strict NewType tycon tc_tvs -- Newtypes + (ConDecl name ex_tvs ex_ctxt details) + = ASSERT( null ex_tvs && null (unLoc ex_ctxt) ) + do { let tc_datacon field_lbls arg_ty + = do { arg_ty' <- tcHsKindedType arg_ty -- No bang on newtype + ; buildDataCon (unLoc name) False {- Prefix -} + True {- Vanilla -} [NotMarkedStrict] + (map unLoc field_lbls) + tc_tvs [] [arg_ty'] + tycon (mkTyVarTys tc_tvs) } + ; case details of + PrefixCon [arg_ty] -> tc_datacon [] arg_ty + RecCon [(field_lbl, arg_ty)] -> tc_datacon [field_lbl] arg_ty } + +tcConDecl unbox_strict DataType tycon tc_tvs -- Ordinary data types + (ConDecl name ex_tvs ex_ctxt details) + = tcTyVarBndrs ex_tvs $ \ ex_tvs' -> do + { ex_ctxt' <- tcHsKindedContext ex_ctxt + ; let + is_vanilla = null ex_tvs && null (unLoc ex_ctxt) + -- Vanilla iff no ex_tvs and no context + + tc_datacon is_infix field_lbls btys + = do { let { bangs = map getBangStrictness btys } + ; arg_tys <- mappM tcHsBangType btys + ; buildDataCon (unLoc name) is_infix is_vanilla + (argStrictness unbox_strict tycon bangs arg_tys) + (map unLoc field_lbls) + (tc_tvs ++ ex_tvs') + ex_ctxt' + arg_tys + tycon (mkTyVarTys tc_tvs) } + ; case details of + PrefixCon btys -> tc_datacon False [] btys + InfixCon bty1 bty2 -> tc_datacon True [] [bty1,bty2] + RecCon fields -> do { checkTc is_vanilla (exRecConErr name) + ; let { (field_names, btys) = unzip fields } + ; tc_datacon False field_names btys } } + +tcConDecl unbox_strict DataType tycon tc_tvs -- GADTs + decl@(GadtDecl name con_ty) + = do { traceTc (text "tcConDecl" <+> ppr name) + ; (tvs, theta, bangs, arg_tys, tc, res_tys) <- tcLHsConSig con_ty + + ; traceTc (text "tcConDecl1" <+> ppr name) + ; let -- Now dis-assemble the type, and check its form + is_vanilla = null theta && mkTyVarTys tvs `tcEqTypes` res_tys + + -- Vanilla datacons guarantee to use the same + -- type variables as the parent tycon + (tvs', arg_tys', res_tys') + | is_vanilla = (tc_tvs, substTys subst arg_tys, substTys subst res_tys) + | otherwise = (tvs, arg_tys, res_tys) + subst = zipTopTvSubst tvs (mkTyVarTys tc_tvs) + + ; traceTc (text "tcConDecl3" <+> ppr name) + ; buildDataCon (unLoc name) False {- Not infix -} is_vanilla + (argStrictness unbox_strict tycon bangs arg_tys) + [{- No field labels -}] + tvs' theta arg_tys' tycon res_tys' } + +------------------- +tcStupidTheta :: LHsContext Name -> [LConDecl Name] -> TcM (Maybe ThetaType) +-- For GADTs we don't allow a context on the data declaration +-- whereas for standard Haskell style data declarations, we do +tcStupidTheta ctxt (L _ (ConDecl _ _ _ _) : _) + = do { theta <- tcHsKindedContext ctxt; return (Just theta) } +tcStupidTheta ctxt other -- Includes an empty constructor list + = ASSERT( null (unLoc ctxt) ) return Nothing + +------------------- +argStrictness :: Bool -- True <=> -funbox-strict_fields + -> TyCon -> [HsBang] + -> [TcType] -> [StrictnessMark] +argStrictness unbox_strict tycon bangs arg_tys + = ASSERT( length bangs == length arg_tys ) + zipWith (chooseBoxingStrategy unbox_strict tycon) arg_tys bangs + +-- 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 :: [RenamedHsDecl] -> TcM s [Bag RenamedHsDecl] -sortByDependency 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 ty_cls_decls - scc_bags = map bag_acyclic decl_sccs - in - returnTc (scc_bags) +checkCycleErrs :: [LTyClDecl Name] -> TcM () +checkCycleErrs tyclss + | null cls_cycles + = return () + | otherwise + = do { mappM_ recClsErr cls_cycles + ; failM } -- Give up now, because later checkValidTyCl + -- will loop if the synonym is recursive + where + cls_cycles = calcClassCycles tyclss + +checkValidTyCl :: TyClDecl 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 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) (tyConStupidTheta tc) `thenM_` + + -- Check arg types of data constructors + mappM_ (checkValidDataCon tc) data_cons `thenM_` + + -- Check that fields with the same name share a type + mappM_ check_fields groups where - syn_decls = listToBag (filter is_syn_decl decls) - ty_cls_decls = listToBag (filter is_ty_cls_decl decls) - cls_decls = listToBag (filter is_cls_decl decls) + syn_ctxt = TySynCtxt name + name = tyConName tc + (_, syn_rhs) = getSynTyConDefn tc + data_cons = tyConDataCons tc + + groups = equivClasses cmp_fld (concatMap get_fields data_cons) + cmp_fld (f1,_) (f2,_) = f1 `compare` f2 + get_fields con = dataConFieldLabels con `zip` dataConOrigArgTys con + -- dataConFieldLabels may return the empty list, which is fine + + check_fields fields@((first_field_label, field_ty) : 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 . snd) other_fields) + (fieldTypeMisMatch first_field_label) + +------------------------------- +checkValidDataCon :: TyCon -> DataCon -> TcM () +checkValidDataCon tc con + = addErrCtxt (dataConCtxt con) $ + do { checkTc (dataConTyCon con == tc) (badDataConTyCon con) + ; checkValidType ctxt (idType (dataConWrapId con)) } + + -- This checks the argument types and + -- ambiguity of the existential context (if any) + -- + -- Note [Sept 04] Now that tvs is all the tvs, this + -- test doesn't actually check anything +-- ; checkFreeness tvs ex_theta } + where + ctxt = ConArgCtxt (dataConName con) + (tvs, ex_theta, _, _, _) = dataConSig con - -bag_acyclic (AcyclicSCC scc) = unitBag scc -bag_acyclic (CyclicSCC sccs) = sccs +------------------------------- +checkValidClass :: Class -> TcM () +checkValidClass cls + = do { -- CHECK ARITY 1 FOR HASKELL 1.4 + gla_exts <- doptM Opt_GlasgowExts -is_syn_decl (TyD (TySynonym _ _ _ _)) = True -is_syn_decl _ = False + -- Check that the class is unary, unless GlaExs + ; checkTc (notNull tyvars) (nullaryClassErr cls) + ; checkTc (gla_exts || unary) (classArityErr cls) -is_ty_cls_decl (TyD _) = True -is_ty_cls_decl (ClD _) = True -is_ty_cls_decl other = False + -- Check the super-classes + ; checkValidTheta (ClassSCCtxt (className cls)) theta -is_cls_decl (ClD _) = True -is_cls_decl other = False + -- Check the class operations + ; mappM_ check_op op_stuff -fmt_decl decl - = (ppr PprForUser name, getSrcLoc name) + -- 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 - name = hsDeclName decl -\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_con 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) - -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_ty ty -get_bty (Unbanged ty) = get_ty ty - -get_ty (MonoTyVar name) - = if isTvOcc (nameOccName name) then emptyUniqSet else set_name name -get_ty (MonoTyApp ty1 ty2) - = unionUniqSets (get_ty ty1) (get_ty ty2) -get_ty (MonoFunTy ty1 ty2) - = unionUniqSets (get_ty ty1) (get_ty ty2) -get_ty (MonoListTy tc ty) - = set_name tc `unionUniqSets` get_ty ty -get_ty (MonoTupleTy tc tys) - = set_name tc `unionUniqSets` get_tys tys -get_ty (HsForAllTy _ ctxt mty) - = get_ctxt ctxt `unionUniqSets` get_ty mty -get_ty other = panic "TcTyClsDecls:get_ty" - -get_tys tys - = unionManyUniqSets (map get_ty tys) - -get_sigs sigs - = unionManyUniqSets (map get_sig sigs) - where - get_sig (ClassOpSig _ _ ty _) = get_ty ty - get_sig other = panic "TcTyClsDecls:get_sig" - -set_name name = unitUniqSet (uniqueOf name) - -set_to_bag set = listToBag (uniqSetToList set) -\end{code} + (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 -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. + ; checkValidType (FunSigCtxt op_name) tau -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 type mentions at least one of + -- the class type variables + ; checkTc (any (`elemVarSet` tyVarsOfType tau) tyvars) + (noClassTyVarErr cls sel_id) -class C a where - op :: D b => a -> b -> b + -- Check that for a generic method, the type of + -- the method is sufficiently simple + ; checkTc (dm /= GenDefMeth || validGenericMethodType tau) + (badGenericMethodType op_name op_ty) + } + where + op_name = idName sel_id + op_ty = idType sel_id + (_,theta,tau) = tcSplitSigmaTy op_ty -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. +--------------------------------------------------------------------- +fieldTypeMisMatch field_name + = sep [ptext SLIT("Different constructors give different types for field"), quotes (ppr field_name)] -\begin{code} -get_binders :: Bag RenamedHsDecl - -> ([HsTyVar Name], -- TyVars; no dups - [(Name, Maybe Arity)], -- Tycons; no dups; arities for synonyms - [Name]) -- Classes; no dups +dataConCtxt con = sep [ptext SLIT("When checking the data constructor:"), + nest 2 (ex_part <+> pprThetaArrow ex_theta <+> ppr con <+> arg_part)] + where + (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, lists, and tuples")]) + +recSynErr syn_decls + = setSrcSpan (getLoc (head sorted_decls)) $ + addErr (sep [ptext SLIT("Cycle in type synonym declarations:"), + nest 2 (vcat (map ppr_decl sorted_decls))]) + where + sorted_decls = sortLocated syn_decls + ppr_decl (L loc decl) = ppr loc <> colon <+> ppr decl -get_binders decls = (bagToList tyvars, bagToList tycons, bagToList classes) +recClsErr cls_decls + = setSrcSpan (getLoc (head sorted_decls)) $ + addErr (sep [ptext SLIT("Cycle in class declarations (via superclasses):"), + nest 2 (vcat (map ppr_decl sorted_decls))]) 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 - pty_tvs other = emptyBag -\end{code} + sorted_decls = sortLocated cls_decls + ppr_decl (L loc decl) = ppr loc <> colon <+> ppr (decl { tcdSigs = [] }) +sortLocated :: [Located a] -> [Located a] +sortLocated things = sortLe le things + where + le (L l1 _) (L l2 _) = l1 <= l2 -\begin{code} -typeCycleErr syn_cycles sty - = ppAboves (map (pp_cycle sty "Cycle in type declarations ...") syn_cycles) +exRecConErr name + = ptext SLIT("Can't combine named fields with locally-quantified type variables or context") + $$ + (ptext SLIT("In the declaration of data constructor") <+> ppr name) -classCycleErr cls_cycles sty - = ppAboves (map (pp_cycle sty "Cycle in class declarations ...") cls_cycles) +badDataConTyCon data_con + = hang (ptext SLIT("Data constructor does not return its parent type:")) + 2 (ppr data_con) -pp_cycle sty str things - = ppHang (ppStr str) - 4 (ppAboves (map pp_thing things)) - where - pp_thing (pp_name, loc) - = ppCat [pp_name, ppr sty loc] +badGadtDecl tc_name + = vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+> quotes (ppr tc_name) + , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow GADTs")) ] \end{code}