X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcTyClsDecls.lhs;h=a03b3497807e370d29305594cbaf99f49cd00ef9;hb=10ab808b4c8575f62bcc7998e5ab45fa0e0d33c5;hp=0da4dafd5857026265c980983308660738048bc7;hpb=6942766ac64f71b57c85a4069900b383495e2bdb;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcTyClsDecls.lhs b/ghc/compiler/typecheck/TcTyClsDecls.lhs index 0da4daf..a03b349 100644 --- a/ghc/compiler/typecheck/TcTyClsDecls.lhs +++ b/ghc/compiler/typecheck/TcTyClsDecls.lhs @@ -10,44 +10,48 @@ module TcTyClsDecls ( #include "HsVersions.h" -import HsSyn ( TyClDecl(..), - ConDecl(..), Sig(..), HsPred(..), - tyClDeclName, hsTyVarNames, tyClDeclTyVars, - isTypeOrClassDecl, isClassDecl, isSynDecl, isClassOpSig +import HsSyn ( TyClDecl(..), HsConDetails(..), HsTyVarBndr(..), + ConDecl(..), Sig(..), BangType(..), HsBang(..), NewOrData(..), + tyClDeclTyVars, getBangType, getBangStrictness, isSynDecl, + LTyClDecl, tcdName, LHsTyVarBndr ) -import RnHsSyn ( RenamedTyClDecl, tyClDeclFVs ) -import BasicTypes ( RecFlag(..), NewOrData(..) ) -import HscTypes ( implicitTyThingIds ) - +import BasicTypes ( RecFlag(..), StrictnessMark(..) ) +import HscTypes ( implicitTyThings, lookupFixity ) +import BuildTyCl ( buildClass, buildAlgTyCon, buildSynTyCon, buildDataCon, + mkDataTyConRhs, mkNewTyConRhs ) import TcRnMonad -import TcEnv ( TcTyThing(..), TyThing(..), TyThingDetails(..), - tcExtendKindEnv, tcLookup, tcLookupGlobal, tcExtendGlobalEnv, - isLocalThing ) -import TcTyDecls ( tcTyDecl, kcConDetails ) -import TcClassDcl ( tcClassDecl1 ) -import TcInstDcls ( tcAddDeclCtxt ) -import TcMonoType ( kcHsTyVars, kcHsType, kcHsLiftedSigType, kcHsContext, mkTyClTyVars ) -import TcMType ( newKindVar, zonkKindEnv, checkValidTyCon, checkValidClass ) +import TcEnv ( TcTyThing(..), TyThing(..), + tcLookupLocated, tcLookupLocatedGlobal, + tcExtendGlobalEnv, tcExtendKindEnv, + tcExtendRecEnv, tcLookupTyVar ) +import TcTyDecls ( calcTyConArgVrcs, calcRecFlags, calcClassCycles, calcSynCycles ) +import TcClassDcl ( tcClassSigs, tcAddDeclCtxt ) +import TcHsType ( kcHsTyVars, kcHsLiftedSigType, kcHsSigType, kcHsType, + kcHsContext, tcTyVarBndrs, tcHsKindedType, tcHsKindedContext ) +import TcMType ( newKindVar, checkValidTheta, checkValidType, checkFreeness, + UserTypeCtxt(..), SourceTyCtxt(..) ) import TcUnify ( unifyKind ) -import TcType ( Type, Kind, TcKind, mkArrowKind, liftedTypeKind, zipFunTys ) -import Type ( splitTyConApp_maybe ) -import Variance ( calcTyConArgVrcs ) -import Class ( Class, mkClass, classTyCon ) -import TyCon ( TyCon, ArgVrcs, AlgTyConFlavour(..), DataConDetails(..), visibleDataCons, - tyConKind, tyConTyVars, tyConDataCons, isNewTyCon, - mkSynTyCon, mkAlgTyCon, mkClassTyCon, mkForeignTyCon - ) -import TysWiredIn ( unitTy ) -import Subst ( substTyWith ) -import DataCon ( dataConOrigArgTys ) -import Var ( varName ) -import FiniteMap -import Digraph ( stronglyConnComp, SCC(..) ) +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, + 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 ) -import NameEnv -import NameSet import Outputable -import Maybes ( mapMaybe ) +import Util ( zipLazy, isSingleton, notNull ) +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} @@ -57,28 +61,6 @@ import Maybes ( mapMaybe ) %* * %************************************************************************ -The main function -~~~~~~~~~~~~~~~~~ -\begin{code} -tcTyAndClassDecls :: [RenamedTyClDecl] - -> TcM [TyThing] -- Returns newly defined things: - -- types, classes and implicit Ids - -tcTyAndClassDecls decls - = tcGroups (stronglyConnComp edges) - where - edges = map mkEdges (filter isTypeOrClassDecl decls) - -tcGroups [] - = returnM [] - -tcGroups (group:groups) - = tcGroup group `thenM` \ (env, new_things1) -> - setGblEnv env $ - tcGroups groups `thenM` \ new_things2 -> - returnM (new_things1 ++ new_things2) -\end{code} - Dealing with a group ~~~~~~~~~~~~~~~~~~~~ Consider a mutually-recursive group, binding @@ -123,114 +105,76 @@ 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} -tcGroup :: SCC RenamedTyClDecl - -> TcM (TcGblEnv, -- Input env extended by types and classes only - [TyThing]) -- Things defined by this group - -tcGroup scc - = -- Step 1 - mappM getInitialKind decls `thenM` \ initial_kinds -> - - -- Step 2 - tcExtendKindEnv initial_kinds (mappM kcTyClDecl decls) `thenM_` - - -- Step 3 - zonkKindEnv initial_kinds `thenM` \ final_kinds -> - - -- Check for loops; if any are found, bale out now - -- because the compiler itself will loop otherwise! - checkNoErrs (checkLoops scc) `thenM` \ is_rec_tycon -> - - -- Tie the knot - traceTc (text "starting" <+> ppr final_kinds) `thenM_` - fixM ( \ ~(rec_details_list, _, rec_all_tyclss) -> - -- Step 4 - let - kind_env = mkNameEnv final_kinds - rec_details = mkNameEnv rec_details_list - - -- Calculate variances, and feed into buildTyConOrClass - rec_vrcs = calcTyConArgVrcs [tc | ATyCon tc <- rec_all_tyclss] - - build_one = buildTyConOrClass is_rec_tycon kind_env - rec_vrcs rec_details - tyclss = map build_one decls - - in - -- Step 5 - -- Extend the environment with the final - -- TyCons/Classes and check the decls - tcExtendGlobalEnv tyclss $ - mappM tcTyClDecl1 decls `thenM` \ tycls_details -> - - -- Return results - getGblEnv `thenM` \ env -> - returnM (tycls_details, env, tyclss) - ) `thenM` \ (_, env, tyclss) -> - - -- Step 7: Check validity - traceTc (text "ready for validity check") `thenM_` - getModule `thenM` \ mod -> - setGblEnv env ( - mappM_ (checkValidTyCl mod) decls - ) `thenM_` - traceTc (text "done") `thenM_` +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 + + ; (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 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") - let -- Add the tycons that come from the classes - -- We want them in the environment because - -- they are mentioned in interface files - implicit_tycons, implicit_ids, all_tyclss :: [TyThing] - implicit_tycons = [ATyCon (classTyCon clas) | AClass clas <- tyclss] - all_tyclss = implicit_tycons ++ tyclss - implicit_ids = [AnId id | id <- implicitTyThingIds all_tyclss] - new_things = implicit_ids ++ all_tyclss - in - returnM (env, new_things) - + -- 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 - decls = case scc of - AcyclicSCC decl -> [decl] - CyclicSCC decls -> decls - -tcTyClDecl1 decl - | isClassDecl decl = tcAddDeclCtxt decl (tcClassDecl1 decl) - | otherwise = tcAddDeclCtxt decl (tcTyDecl decl) - --- We do the validity check over declarations, rather than TyThings --- only so that we can add a nice context with tcAddDeclCtxt -checkValidTyCl this_mod decl - = tcLookupGlobal (tcdName decl) `thenM` \ thing -> - if not (isLocalThing this_mod thing) then - -- Don't bother to check validity for non-local things - returnM () - else - tcAddDeclCtxt decl $ - case thing of - ATyCon tc -> checkValidTyCon tc - AClass cl -> checkValidClass cl + mk_thing (L _ (ClassDecl {tcdLName = L _ name}), ~(AClass cl)) + = (name, AClass cl) + mk_thing (L _ decl, ~(ATyCon tc)) + = (tcdName decl, ATyCon tc) \end{code} %************************************************************************ %* * -\subsection{Step 1: Initial environment} -%* * -%************************************************************************ - -\begin{code} -getInitialKind :: RenamedTyClDecl -> TcM (Name, TcKind) -getInitialKind decl - = kcHsTyVars (tyClDeclTyVars decl) `thenM` \ arg_kinds -> - newKindVar `thenM` \ result_kind -> - returnM (tcdName decl, mk_kind arg_kinds result_kind) - -mk_kind tvs_w_kinds res_kind = foldr (mkArrowKind . snd) res_kind tvs_w_kinds -\end{code} - - -%************************************************************************ -%* * -\subsection{Step 2: Kind checking} + Kind checking %* * %************************************************************************ @@ -247,189 +191,268 @@ 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} -kcTyClDecl :: RenamedTyClDecl -> TcM () - -kcTyClDecl decl@(TySynonym {tcdSynRhs = rhs}) - = kcTyClDeclBody decl $ \ result_kind -> - kcHsType rhs `thenM` \ rhs_kind -> - unifyKind result_kind rhs_kind +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. -kcTyClDecl (ForeignType {}) = returnM () +\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) -kcTyClDecl decl@(TyData {tcdND = new_or_data, tcdCtxt = context, tcdCons = con_decls}) - = kcTyClDeclBody decl $ \ result_kind -> - kcHsContext context `thenM_` - mappM_ kc_con_decl (visibleDataCons con_decls) +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 _ ex_tvs ex_ctxt details loc) - = kcHsTyVars ex_tvs `thenM` \ kind_env -> - tcExtendKindEnv kind_env $ - kcConDetails new_or_data ex_ctxt details - -kcTyClDecl decl@(ClassDecl {tcdCtxt = context, tcdSigs = class_sigs}) - = kcTyClDeclBody decl $ \ result_kind -> - kcHsContext context `thenM_` - mappM_ kc_sig (filter isClassOpSig class_sigs) + 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@(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 - kc_sig (ClassOpSig _ _ op_ty loc) = kcHsLiftedSigType op_ty - -kcTyClDeclBody :: RenamedTyClDecl -> (Kind -> 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 + 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 $ - tcLookup (tcdName decl) `thenM` \ thing -> - let - kind = case thing of - AGlobal (ATyCon tc) -> tyConKind tc - AGlobal (AClass cl) -> tyConKind (classTyCon cl) - AThing kind -> kind - -- For some odd reason, a class doesn't include its kind - - (tyvars_w_kinds, result_kind) = zipFunTys (hsTyVarNames (tyClDeclTyVars decl)) kind - in - tcExtendKindEnv tyvars_w_kinds (thing_inside result_kind) + 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) + liftedTypeKind kinded_tvs) + ; thing_inside kinded_tvs } + +kindedTyVarKind (L _ (KindedTyVar _ k)) = k \end{code} - %************************************************************************ %* * -\subsection{Step 4: Building the tycon/class} +\subsection{Type checking} %* * %************************************************************************ \begin{code} -buildTyConOrClass - :: (Name -> AlgTyConFlavour -> RecFlag) -- Whether it's recursive - -> NameEnv Kind - -> FiniteMap TyCon ArgVrcs -> NameEnv TyThingDetails - -> RenamedTyClDecl -> TyThing - -buildTyConOrClass rec_tycon kenv rec_vrcs rec_details - (TySynonym {tcdName = tycon_name, tcdTyVars = tyvar_names}) - = ATyCon tycon +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 + { ctxt' <- tcHsKindedContext ctxt + ; want_generic <- doptM Opt_Generics + ; tycon <- fixM (\ tycon -> do + { data_cons <- mappM (addLocM (tcConDecl new_or_data tycon tvs' ctxt')) cons + ; let tc_rhs = case new_or_data of + DataType -> mkDataTyConRhs data_cons + NewType -> ASSERT( isSingleton data_cons ) + mkNewTyConRhs (head data_cons) + ; buildAlgTyCon tc_name tvs' ctxt' + tc_rhs arg_vrcs is_rec + (want_generic && canDoGenerics data_cons) + }) + ; return (ATyCon tycon) + } where - tycon = mkSynTyCon tycon_name tycon_kind arity tyvars rhs_ty argvrcs - tycon_kind = lookupNameEnv_NF kenv tycon_name - arity = length tyvar_names - tyvars = mkTyClTyVars tycon_kind tyvar_names - SynTyDetails rhs_ty = lookupNameEnv_NF rec_details tycon_name - argvrcs = lookupWithDefaultFM rec_vrcs bogusVrcs tycon - -buildTyConOrClass rec_tycon kenv rec_vrcs rec_details - (TyData {tcdND = data_or_new, tcdName = tycon_name, - tcdTyVars = tyvar_names}) - = ATyCon tycon + 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 - tycon = mkAlgTyCon tycon_name tycon_kind tyvars ctxt argvrcs - data_cons sel_ids flavour - (rec_tycon tycon_name flavour) gen_info - - DataTyDetails ctxt data_cons sel_ids gen_info = lookupNameEnv_NF rec_details tycon_name - - tycon_kind = lookupNameEnv_NF kenv tycon_name - tyvars = mkTyClTyVars tycon_kind tyvar_names - argvrcs = lookupWithDefaultFM rec_vrcs bogusVrcs tycon - - -- Watch out! mkTyConApp asks whether the tycon is a NewType, - -- so flavour has to be able to answer this question without consulting rec_details - flavour = case data_or_new of - NewType -> NewTyCon (mkNewTyConRep tycon) - DataType | all_nullary data_cons -> EnumTyCon - | otherwise -> DataTyCon - - all_nullary (DataCons cons) = all (null . dataConOrigArgTys) cons - all_nullary other = False -- Safe choice for unknown data types - -- NB (null . dataConOrigArgTys). It used to say isNullaryDataCon - -- but that looks at the *representation* arity, and that in turn - -- depends on deciding whether to unpack the args, and that - -- depends on whether it's a data type or a newtype --- so - -- in the recursive case we can get a loop. This version is simple! - -buildTyConOrClass rec_tycon kenv rec_vrcs rec_details - (ForeignType {tcdName = tycon_name, tcdExtName = tycon_ext_name}) - = ATyCon (mkForeignTyCon tycon_name tycon_ext_name liftedTypeKind 0 []) - -buildTyConOrClass rec_tycon kenv rec_vrcs rec_details - (ClassDecl {tcdName = class_name, tcdTyVars = tyvar_names, tcdFDs = fundeps} ) - = AClass clas + 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 is_infix field_lbls btys + = do { let { ubtys = map unLoc btys } + ; arg_tys <- mappM (tcHsKindedType . getBangType) ubtys + ; buildDataCon (unLoc name) is_infix + (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 False [] btys + InfixCon bty1 bty2 -> tc_datacon True [] [bty1,bty2] + RecCon fields -> do { checkTc (null ex_tvs') (exRecConErr name) + ; let { (field_names, btys) = unzip fields } + ; tc_datacon False 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 - clas = mkClass class_name tyvars fds - sc_theta sc_sel_ids op_items - tycon - - tycon = mkClassTyCon tycon_name class_kind tyvars - argvrcs dict_con - clas -- Yes! It's a dictionary - flavour - (rec_tycon class_name flavour) - -- A class can be recursive, and in the case of newtypes - -- this matters. For example - -- class C a where { op :: C b => a -> b -> Int } - -- Because C has only one operation, it is represented by - -- a newtype, and it should be a *recursive* newtype. - -- [If we don't make it a recursive newtype, we'll expand the - -- newtype like a synonym, but that will lead toan inifinite type - - ClassDetails sc_theta sc_sel_ids op_items dict_con tycon_name - = lookupNameEnv_NF rec_details class_name - - class_kind = lookupNameEnv_NF kenv class_name - tyvars = mkTyClTyVars class_kind tyvar_names - argvrcs = lookupWithDefaultFM rec_vrcs bogusVrcs tycon - - flavour = case dataConOrigArgTys dict_con of - -- The tyvars in the datacon are the same as in the class - [rep_ty] -> NewTyCon rep_ty - other -> DataTyCon - - -- We can find the functional dependencies right away, - -- and it is vital to do so. Why? Because in the next pass - -- we check for ambiguity in all the type signatures, and we - -- need the functional dependcies to be done by then - fds = [(map lookup xs, map lookup ys) | (xs,ys) <- fundeps] - tyvar_env = mkNameEnv [(varName tv, tv) | tv <- tyvars] - lookup = lookupNameEnv_NF tyvar_env - -bogusVrcs = panic "Bogus tycon arg variances" -\end{code} - -\begin{code} -mkNewTyConRep :: TyCon -- The original type constructor - -> Type -- Chosen representation type - -- (guaranteed not to be another newtype) - --- Find the representation type for this newtype TyCon --- Remember that the representation type is the ultimate representation --- type, looking through other newtypes. --- --- The non-recursive newtypes are easy, because they look transparent --- to splitTyConApp_maybe, but recursive ones really are represented as --- TyConApps (see TypeRep). --- --- The trick is to to deal correctly with recursive newtypes --- such as newtype T = MkT T - -mkNewTyConRep tc - = go [] tc - where - -- Invariant: tc is a NewTyCon - -- tcs have been seen before - go tcs tc - | tc `elem` tcs = unitTy - | otherwise - = let - rep_ty = head (dataConOrigArgTys (head (tyConDataCons tc))) - in - case splitTyConApp_maybe rep_ty of - Nothing -> rep_ty - Just (tc', tys) | not (isNewTyCon tc') -> rep_ty - | otherwise -> go1 (tc:tcs) tc' tys - - go1 tcs tc tys = substTyWith (tyConTyVars tc) tys (go tcs tc) + can_unbox = case splitTyConApp_maybe arg_ty of + Nothing -> False + Just (arg_tycon, _) -> not (isRecursiveTyCon tycon) && + isProductTyCon arg_tycon \end{code} %************************************************************************ @@ -438,93 +461,195 @@ mkNewTyConRep tc %* * %************************************************************************ -Dependency analysis -~~~~~~~~~~~~~~~~~~~ +Validity checking is done once the mutually-recursive knot has been +tied, so we can look at things freely. + \begin{code} -checkLoops :: SCC RenamedTyClDecl - -> TcM (Name -> AlgTyConFlavour -> RecFlag) --- Check for illegal loops, --- a) type synonyms --- b) superclass hierarchy --- --- Also return a function that says which tycons are recursive. --- Remember: --- a newtype is recursive if it is part of a recursive --- group consisting only of newtype and synonyms - -checkLoops (AcyclicSCC _) - = returnM (\ _ _ -> NonRecursive) - -checkLoops (CyclicSCC decls) - = let -- CHECK FOR CLASS CYCLES - cls_edges = mapMaybe mkClassEdges decls - cls_cycles = findCycles cls_edges - in - mapM_ (cycleErr "class") cls_cycles `thenM_` - - let -- CHECK FOR SYNONYM CYCLES - syn_edges = map mkEdges (filter isSynDecl decls) - syn_cycles = findCycles syn_edges - in - mapM_ (cycleErr "type synonym") syn_cycles `thenM_` - - let -- CHECK FOR NEWTYPE CYCLES - newtype_edges = map mkEdges (filter is_nt_cycle_decl decls) - newtype_cycles = findCycles newtype_edges - rec_newtypes = mkNameSet [tcdName d | ds <- newtype_cycles, d <- ds] - - rec_tycon name (NewTyCon _) - | name `elemNameSet` rec_newtypes = Recursive - | otherwise = NonRecursive - rec_tycon name other_flavour = Recursive - in - returnM rec_tycon - ----------------------------------------------------- --- A class with one op and no superclasses, or vice versa, --- is treated just like a newtype. --- It's a bit unclean that this test is repeated in buildTyConOrClass -is_nt_cycle_decl (TySynonym {}) = True -is_nt_cycle_decl (TyData {tcdND = NewType}) = True -is_nt_cycle_decl (ClassDecl {tcdCtxt = ctxt, tcdSigs = sigs}) = length ctxt + length sigs == 1 -is_nt_cycle_decl other = False - ----------------------------------------------------- -findCycles edges = [ ds | CyclicSCC ds <- stronglyConnComp edges] - ----------------------------------------------------- -mkEdges :: RenamedTyClDecl -> (RenamedTyClDecl, Name, [Name]) -mkEdges decl = (decl, tyClDeclName decl, nameSetToList (tyClDeclFVs decl)) - ----------------------------------------------------- --- mk_cls_edges looks only at the context of class decls --- Its used when we are figuring out if there's a cycle in the --- superclass hierarchy - -mkClassEdges :: RenamedTyClDecl -> Maybe (RenamedTyClDecl, Name, [Name]) -mkClassEdges decl@(ClassDecl {tcdCtxt = ctxt, tcdName = name}) = Just (decl, name, [c | HsClassP c _ <- ctxt]) -mkClassEdges other_decl = Nothing -\end{code} +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) (tyConTheta tc) `thenM_` + + -- Check arg types of data constructors + mappM_ checkValidDataCon data_cons `thenM_` -%************************************************************************ -%* * -\subsection{Error management -%* * -%************************************************************************ + -- Check that fields with the same name share a type + mappM_ check_fields groups -\begin{code} -cycleErr :: String -> [RenamedTyClDecl] -> TcM () + where + 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 + ctxt = ConArgCtxt (dataConName con) + (_, _, ex_tvs, ex_theta, _, _) = dataConSig con -cycleErr kind_of_decl decls - = addErrAt loc (ppr_cycle kind_of_decl decls) + +------------------------------- +checkValidClass :: Class -> TcM () +checkValidClass cls + = do { -- CHECK ARITY 1 FOR HASKELL 1.4 + gla_exts <- doptM Opt_GlasgowExts + + -- Check that the class is unary, unless GlaExs + ; checkTc (notNull tyvars) (nullaryClassErr cls) + ; checkTc (gla_exts || unary) (classArityErr cls) + + -- Check the super-classes + ; checkValidTheta (ClassSCCtxt (className cls)) theta + + -- Check the class operations + ; mappM_ check_op op_stuff + + -- 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 + + ; checkValidType (FunSigCtxt op_name) tau + + -- 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 + + + +--------------------------------------------------------------------- +fieldTypeMisMatch field_name + = sep [ptext SLIT("Different constructors give different types for field"), quotes (ppr field_name)] + +dataConCtxt con = sep [ptext SLIT("When checking the data constructor:"), + nest 2 (ex_part <+> pprThetaArrow ex_theta <+> ppr con <+> arg_part)] where - loc = tcdLoc (head decls) + (_, _, 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 syn_decls + = addSrcSpan (getLoc (head syn_decls)) $ + addErr (sep [ptext SLIT("Cycle in type synonym declarations:"), + nest 2 (vcat (map ppr_decl syn_decls))]) + where + ppr_decl (L loc decl) = ppr loc <> colon <+> ppr decl -ppr_cycle kind_of_decl decls - = hang (ptext SLIT("Cycle in") <+> text kind_of_decl <+> ptext SLIT("declarations:")) - 4 (vcat (map pp_decl decls)) +recClsErr cls_decls + = addSrcSpan (getLoc (head cls_decls)) $ + addErr (sep [ptext SLIT("Cycle in class declarations (via superclasses):"), + nest 2 (vcat (map ppr_decl cls_decls))]) where - pp_decl decl = hsep [quotes (ppr (tcdName decl)), - ptext SLIT("at"), ppr (tcdLoc decl)] + ppr_decl (L loc decl) = ppr loc <> colon <+> ppr (decl { tcdSigs = [] }) + +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}