X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcTyClsDecls.lhs;h=d2f53dec1d4a9e415215f586f521f1d88e59e063;hb=ac10f8408520a30e8437496d320b8b86afda2e8f;hp=d3b82d6ebddb28f40201eabb7350459f78e44034;hpb=9d787ef5a8072b6c1f576f2de1b66edfa59813ed;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcTyClsDecls.lhs b/ghc/compiler/typecheck/TcTyClsDecls.lhs index d3b82d6..d2f53de 100644 --- a/ghc/compiler/typecheck/TcTyClsDecls.lhs +++ b/ghc/compiler/typecheck/TcTyClsDecls.lhs @@ -10,175 +10,187 @@ module TcTyClsDecls ( #include "HsVersions.h" -import HsSyn ( HsDecl(..), TyClDecl(..), - HsType(..), HsTyVar, - ConDecl(..), ConDetails(..), BangType(..), - Sig(..), - tyClDeclName, isClassDecl, isSynDecl +import HsSyn ( TyClDecl(..), HsConDetails(..), HsTyVarBndr(..), + ConDecl(..), Sig(..), , NewOrData(..), ResType(..), + tyClDeclTyVars, isSynDecl, hsConArgs, + LTyClDecl, tcdName, hsTyVarName, LHsTyVarBndr ) -import RnHsSyn ( RenamedHsDecl, RenamedTyClDecl, listTyCon_name, tupleTyCon_name ) -import BasicTypes ( RecFlag(..), NewOrData(..), Arity ) - -import TcMonad -import Inst ( InstanceMapper ) -import TcClassDcl ( kcClassDecl, tcClassDecl1 ) -import TcEnv ( ValueEnv, TcTyThing(..), - tcExtendTypeEnv, getAllEnvTyCons +import HsTypes ( HsBang(..), getBangStrictness ) +import BasicTypes ( RecFlag(..), StrictnessMark(..) ) +import HscTypes ( implicitTyThings, ModDetails ) +import BuildTyCl ( buildClass, buildAlgTyCon, buildSynTyCon, buildDataCon, + mkDataTyConRhs, mkNewTyConRhs ) +import TcRnMonad +import TcEnv ( TyThing(..), + tcLookupLocated, tcLookupLocatedGlobal, + tcExtendGlobalEnv, tcExtendKindEnv, tcExtendKindEnvTvs, + tcExtendRecEnv, tcLookupTyVar ) +import TcTyDecls ( calcTyConArgVrcs, calcRecFlags, calcClassCycles, calcSynCycles ) +import TcClassDcl ( tcClassSigs, tcAddDeclCtxt ) +import TcHsType ( kcHsTyVars, kcHsLiftedSigType, kcHsType, + kcHsContext, tcTyVarBndrs, tcHsKindedType, tcHsKindedContext, + kcHsSigType, tcHsBangType, tcLHsConResTy, tcDataKindSig ) +import TcMType ( newKindVar, checkValidTheta, checkValidType, + -- checkFreeness, + UserTypeCtxt(..), SourceTyCtxt(..) ) +import TcType ( TcKind, TcType, tyVarsOfType, mkPhiTy, + mkArrowKind, liftedTypeKind, mkTyVarTys, + tcSplitSigmaTy, tcEqTypes, tcGetTyVar_maybe ) +import Type ( splitTyConApp_maybe, + -- pprParendType, pprThetaArrow ) -import TcTyDecls ( tcTyDecl, kcTyDecl ) -import TcMonoType ( kcHsTyVar ) -import TcType ( TcKind, newKindVar, newKindVars, kindToTcKind, zonkTcKindToKind ) - -import Type ( mkArrowKind, boxedTypeKind, mkDictTy ) - -import Class ( Class, classBigSig ) -import Var ( TyVar, tyVarKind ) -import FiniteMap -import Bag -import VarSet -import Digraph ( stronglyConnComp, SCC(..) ) -import Name ( Name, NamedThing(..), getSrcLoc, isTvOcc, nameOccName ) +import Kind ( mkArrowKinds, splitKindFunTys ) +import Generics ( validGenericMethodType, canDoGenerics ) +import Class ( Class, className, classTyCon, DefMeth(..), classBigSig, classTyVars ) +import TyCon ( TyCon, ArgVrcs, AlgTyConRhs( AbstractTyCon ), + tyConDataCons, mkForeignTyCon, isProductTyCon, isRecursiveTyCon, + tyConStupidTheta, synTyConRhs, isSynTyCon, tyConName ) +import DataCon ( DataCon, dataConWrapId, dataConName, + dataConFieldLabels, dataConTyCon, + dataConTyVars, dataConFieldType, dataConResTys ) +import Var ( TyVar, idType, idName ) +import VarSet ( elemVarSet, mkVarSet ) +import Name ( Name, getSrcLoc ) import Outputable -import Maybes ( mapMaybe, expectJust ) -import UniqSet ( UniqSet, emptyUniqSet, - unitUniqSet, unionUniqSets, - unionManyUniqSets, uniqSetToList ) -import ErrUtils ( Message ) -import SrcLoc ( SrcLoc ) -import TyCon ( TyCon, ArgVrcs ) -import Variance ( calcTyConArgVrcs ) -import Unique ( Unique, Uniquable(..) ) -import UniqFM ( listToUFM, lookupUFM ) +import Maybe ( isJust, fromJust ) +import Unify ( tcMatchTys, tcMatchTyX ) +import Util ( zipLazy, isSingleton, notNull, sortLe ) +import List ( partition ) +import SrcLoc ( Located(..), unLoc, getLoc, srcLocSpan ) +import ListSetOps ( equivClasses ) +import List ( delete ) +import Digraph ( SCC(..) ) +import DynFlags ( DynFlag( Opt_GlasgowExts, Opt_Generics, + Opt_UnboxStrictFields ) ) \end{code} -The main function -~~~~~~~~~~~~~~~~~ -\begin{code} -tcTyAndClassDecls :: ValueEnv -> InstanceMapper -- Knot tying stuff - -> [RenamedHsDecl] - -> TcM s TcEnv - -tcTyAndClassDecls unf_env inst_mapper decls - = sortByDependency decls `thenTc` \ groups -> - tcGroups unf_env inst_mapper groups - -tcGroups unf_env inst_mapper [] - = tcGetEnv `thenNF_Tc` \ env -> - returnTc env - -tcGroups unf_env inst_mapper (group:groups) - = tcGroup unf_env inst_mapper group `thenTc` \ env -> - tcSetEnv env $ - tcGroups unf_env inst_mapper groups -\end{code} + +%************************************************************************ +%* * +\subsection{Type checking for type and class declarations} +%* * +%************************************************************************ Dealing with a group ~~~~~~~~~~~~~~~~~~~~ - -The knot-tying parameters: @rec_tyclss@ is an alist mapping @Name@s to -@TcTyThing@s. @rec_vrcs@ is a finite map from @Name@s to @ArgVrcs@s. - -\begin{code} -tcGroup :: ValueEnv -> InstanceMapper -> SCC RenamedTyClDecl -> TcM s TcEnv -tcGroup unf_env inst_mapper scc - = -- Do kind checking - mapNF_Tc getTyBinding1 decls `thenNF_Tc` \ ty_env_stuff1 -> - tcExtendTypeEnv ty_env_stuff1 (mapTc kcDecl decls) `thenTc_` - - -- Tie the knot --- traceTc (ppr (map fst ty_env_stuff1)) `thenTc_` - fixTc ( \ ~(rec_tyclss, rec_vrcs, _) -> - let - rec_env = listToUFM rec_tyclss - in +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 + +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. - -- Do type checking - mapNF_Tc (getTyBinding2 rec_env) ty_env_stuff1 `thenNF_Tc` \ ty_env_stuff2 -> - tcExtendTypeEnv ty_env_stuff2 $ - mapTc (tcDecl is_rec_group unf_env inst_mapper rec_vrcs) decls - `thenTc` \ tyclss -> - - tcGetEnv `thenTc` \ env -> - let - tycons = getAllEnvTyCons env - vrcs = calcTyConArgVrcs tycons - in - - returnTc (tyclss, vrcs, env) - ) `thenTc` \ (_, _, env) -> --- traceTc (text "done" <+> ppr (map fst ty_env_stuff1)) `thenTc_` - returnTc env - where - is_rec_group = case scc of - AcyclicSCC _ -> NonRecursive - CyclicSCC _ -> Recursive - decls = case scc of - AcyclicSCC decl -> [decl] - CyclicSCC decls -> decls -\end{code} +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 -Dealing with one decl -~~~~~~~~~~~~~~~~~~~~~ -\begin{code} -kcDecl decl - = tcAddDeclCtxt decl $ - if isClassDecl decl then - kcClassDecl decl - else - kcTyDecl decl +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. -tcDecl :: RecFlag -- True => recursive group - -> ValueEnv -> InstanceMapper -> FiniteMap Name ArgVrcs - -> RenamedTyClDecl -> TcM s (Name, TcTyThing) -tcDecl is_rec_group unf_env inst_mapper vrcs_env decl - = tcAddDeclCtxt decl $ --- traceTc (text "Starting" <+> ppr name) `thenTc_` - if isClassDecl decl then - tcClassDecl1 unf_env inst_mapper vrcs_env decl `thenTc` \ clas -> --- traceTc (text "Finished" <+> ppr name) `thenTc_` - returnTc (getName clas, AClass clas) - else - tcTyDecl is_rec_group vrcs_env decl `thenTc` \ tycon -> --- traceTc (text "Finished" <+> ppr name) `thenTc_` - returnTc (getName tycon, ATyCon tycon) +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 :: ModDetails -> [LTyClDecl Name] + -> TcM TcGblEnv -- Input env extended by types and classes + -- and their implicit Ids,DataCons +tcTyAndClassDecls boot_details decls + = do { -- First check for cyclic type synonysm or classes + -- See notes with checkCycleErrs + checkCycleErrs decls + ; mod <- getModule + ; traceTc (text "tcTyAndCl" <+> ppr mod) + ; (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_details 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 - name = tyClDeclName decl - - -tcAddDeclCtxt decl thing_inside - = tcAddSrcLoc loc $ - tcAddErrCtxt ctxt $ - thing_inside - where - (name, loc, thing) - = case decl of - (ClassDecl _ name _ _ _ _ _ _ _ loc) -> (name, loc, "class") - (TySynonym name _ _ loc) -> (name, loc, "type synonym") - (TyData NewType _ name _ _ _ _ loc) -> (name, loc, "data type") - (TyData DataType _ name _ _ _ _ loc) -> (name, loc, "newtype") - - ctxt = hsep [ptext SLIT("In the"), text thing, - ptext SLIT("declaration for"), quotes (ppr name)] + mk_thing (L _ (ClassDecl {tcdLName = L _ name}), ~(AClass cl)) + = (name, AClass cl) + mk_thing (L _ decl, ~(ATyCon tc)) + = (tcdName decl, ATyCon tc) \end{code} -getTyBinders -~~~~~~~~~~~ -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. - *and* the existentially quantified contexts in datacon decls - -Why do we need to grab all these type variables at once, including -those locally-quantified type variables in class op signatures? - - [Incidentally, this only works because the names are all unique by now.] +%************************************************************************ +%* * + Kind checking +%* * +%************************************************************************ -Because we can only commit to the final kind of a type variable when -we've completed the mutually recursive group. For example: +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 @@ -190,190 +202,627 @@ 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. +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} -getTyBinding1 :: RenamedTyClDecl -> NF_TcM s (Name, (TcKind, Maybe Arity, TcTyThing)) -getTyBinding1 (TySynonym name tyvars _ _) - = mapNF_Tc kcHsTyVar tyvars `thenNF_Tc` \ arg_kinds -> - newKindVar `thenNF_Tc` \ result_kind -> - returnNF_Tc (name, (foldr mkArrowKind result_kind arg_kinds, - Just (length tyvars), - ATyCon (pprPanic "ATyCon: syn" (ppr name)))) - -getTyBinding1 (TyData _ _ name tyvars _ _ _ _) - = mapNF_Tc kcHsTyVar tyvars `thenNF_Tc` \ arg_kinds -> - returnNF_Tc (name, (foldr mkArrowKind boxedTypeKind arg_kinds, - Nothing, - ATyCon (error "ATyCon: data"))) - -getTyBinding1 (ClassDecl _ name tyvars _ _ _ _ _ _ _) - = mapNF_Tc kcHsTyVar tyvars `thenNF_Tc` \ arg_kinds -> - returnNF_Tc (name, (foldr mkArrowKind boxedTypeKind arg_kinds, - Just (length tyvars), - AClass (error "AClass"))) - --- Zonk the kind to its final form, and lookup the --- recursive tycon/class -getTyBinding2 rec_env (name, (tc_kind, maybe_arity, thing)) - = zonkTcKindToKind tc_kind `thenNF_Tc` \ kind -> - returnNF_Tc (name, (kind, maybe_arity, mk_thing thing (lookupUFM rec_env name))) +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) +-- Only for data type and class declarations +-- Get as much info as possible from the data or class decl, +-- so as to maximise usefulness of error messages +getInitialKind (L _ decl) + = do { arg_kinds <- mapM (mk_arg_kind . unLoc) (tyClDeclTyVars decl) + ; res_kind <- mk_res_kind decl + ; return (tcdName decl, mkArrowKinds arg_kinds res_kind) } + where + mk_arg_kind (UserTyVar _) = newKindVar + mk_arg_kind (KindedTyVar _ kind) = return kind + + mk_res_kind (TyData { tcdKindSig = Just kind }) = return kind + -- On GADT-style declarations we allow a kind signature + -- data T :: *->* where { ... } + mk_res_kind other = return liftedTypeKind + + +---------------- +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 + +kindedTyVarKind (L _ (KindedTyVar _ k)) = k + +------------------------------------------------------------------------ +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 expl ex_tvs ex_ctxt details res) = do + kcHsTyVars ex_tvs $ \ex_tvs' -> do + ex_ctxt' <- kcHsContext ex_ctxt + details' <- kc_con_details details + res' <- case res of + ResTyH98 -> return ResTyH98 + ResTyGADT ty -> return . ResTyGADT =<< kcHsSigType ty + return (ConDecl name expl ex_tvs' ex_ctxt' details' res') + + 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 { is_boot <- tcIsHsBoot + ; checkTc (not is_boot) badBootClassDeclErr + ; ctxt' <- kcHsContext ctxt + ; sigs' <- mappM (wrapLocM kc_sig) sigs + ; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdSigs = sigs'}) } where - mk_thing (ATyCon _) ~(Just (ATyCon tc)) = ATyCon tc - mk_thing (AClass _) ~(Just (AClass cls)) = AClass cls + kc_sig (TypeSig nm op_ty) = do { op_ty' <- kcHsLiftedSigType op_ty + ; return (TypeSig nm op_ty') } + kc_sig other_sig = return other_sig + +kcTyClDecl decl@(ForeignType {}) + = return decl + +kcTyClDeclBody :: TyClDecl Name + -> ([LHsTyVarBndr Name] -> TcM a) + -> TcM a +-- getInitialKind has made a suitably-shaped kind for the type or class +-- Unpack it, and attribute those kinds to the type variables +-- 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 $ + do { tc_ty_thing <- tcLookupLocated (tcdLName decl) + ; let tc_kind = case tc_ty_thing of { AThing k -> k } + (kinds, _) = splitKindFunTys tc_kind + hs_tvs = tcdTyVars decl + kinded_tvs = ASSERT( length kinds >= length hs_tvs ) + [ L loc (KindedTyVar (hsTyVarName tv) k) + | (L loc tv, k) <- zip hs_tvs kinds] + ; tcExtendKindEnvTvs kinded_tvs (thing_inside kinded_tvs) } \end{code} %************************************************************************ %* * -\subsection{Dependency analysis} +\subsection{Type checking} %* * %************************************************************************ -Dependency analysis -~~~~~~~~~~~~~~~~~~~ \begin{code} -sortByDependency :: [RenamedHsDecl] -> TcM s [SCC RenamedTyClDecl] -sortByDependency decls - = let -- CHECK FOR CLASS CYCLES - cls_sccs = stronglyConnComp (mapMaybe mk_cls_edges tycl_decls) - cls_cycles = [ decls | CyclicSCC decls <- cls_sccs] - in - checkTc (null cls_cycles) (classCycleErr cls_cycles) `thenTc_` - - let -- CHECK FOR SYNONYM CYCLES - syn_sccs = stronglyConnComp (filter is_syn_decl edges) - syn_cycles = [ decls | CyclicSCC decls <- syn_sccs] - - in - checkTc (null syn_cycles) (typeCycleErr syn_cycles) `thenTc_` - - -- DO THE MAIN DEPENDENCY ANALYSIS - let - decl_sccs = stronglyConnComp edges - in - returnTc decl_sccs - where - tycl_decls = [d | TyClD d <- decls] - edges = map mk_edges tycl_decls +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, tcdKindSig = mb_ksig, tcdCons = cons}) + = tcTyVarBndrs tvs $ \ tvs' -> do + { extra_tvs <- tcDataKindSig mb_ksig + ; let final_tvs = tvs' ++ extra_tvs + ; stupid_theta <- tcHsKindedContext ctxt + ; want_generic <- doptM Opt_Generics + ; unbox_strict <- doptM Opt_UnboxStrictFields + ; gla_exts <- doptM Opt_GlasgowExts + ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file? + + -- Check that we don't use GADT syntax in H98 world + ; checkTc (gla_exts || h98_syntax) (badGadtDecl tc_name) + + -- Check that there's at least one condecl, + -- or else we're reading an interface file, or -fglasgow-exts + ; checkTc (not (null cons) || gla_exts || is_boot) + (emptyConDeclsErr tc_name) - is_syn_decl (d, _, _) = isSynDecl d - is_cls_decl (d, _, _) = isClassDecl d + -- Check that a newtype has exactly one constructor + ; checkTc (new_or_data == DataType || isSingleton cons) + (newtypeConError tc_name (length cons)) + + ; tycon <- fixM (\ tycon -> do + { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data + tycon final_tvs)) + cons + ; let tc_rhs + | null cons && is_boot -- In a hs-boot file, empty cons means + = AbstractTyCon -- "don't know"; hence Abstract + | otherwise + = case new_or_data of + DataType -> mkDataTyConRhs data_cons + NewType -> ASSERT( isSingleton data_cons ) + mkNewTyConRhs tycon (head data_cons) + ; buildAlgTyCon tc_name final_tvs stupid_theta 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 _ (ConDecl { con_res = ResTyGADT _ }) : _ -> 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 ResTyH98) + = 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) } + + -- Check that a newtype has no existential stuff + ; checkTc (null ex_tvs && null (unLoc ex_ctxt)) (newtypeExError name) + + ; case details of + PrefixCon [arg_ty] -> tc_datacon [] arg_ty + RecCon [(field_lbl, arg_ty)] -> tc_datacon [field_lbl] arg_ty + other -> failWithTc (newtypeFieldErr name (length (hsConArgs details))) + -- Check that the constructor has exactly one field + } + +tcConDecl unbox_strict DataType tycon tc_tvs -- Data types + (ConDecl name _ tvs ctxt details res_ty) + = tcTyVarBndrs tvs $ \ tvs' -> do + { ctxt' <- tcHsKindedContext ctxt + ; (data_tc, res_ty_args) <- tcResultType tycon tc_tvs res_ty + ; let + con_tvs = case res_ty of + ResTyH98 -> tc_tvs ++ tvs' + ResTyGADT _ -> tryVanilla tvs' res_ty_args + + -- Vanilla iff result type matches the quantified vars exactly, + -- and there is no existential context + -- Must check the context too because of implicit params; e.g. + -- data T = (?x::Int) => MkT Int + is_vanilla = res_ty_args `tcEqTypes` mkTyVarTys con_tvs + && null (unLoc ctxt) + + 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) + con_tvs ctxt' arg_tys + data_tc res_ty_args } + -- NB: we put data_tc, the type constructor gotten from the constructor + -- type signature into the data constructor; that way + -- checkValidDataCon can complain if it's wrong. + + ; case details of + PrefixCon btys -> tc_datacon False [] btys + InfixCon bty1 bty2 -> tc_datacon True [] [bty1,bty2] + RecCon fields -> tc_datacon False field_names btys + where + (field_names, btys) = unzip fields + + } + +tcResultType :: TyCon -> [TyVar] -> ResType Name -> TcM (TyCon, [TcType]) +tcResultType tycon tvs ResTyH98 = return (tycon, mkTyVarTys tvs) +tcResultType _ _ (ResTyGADT res_ty) = tcLHsConResTy res_ty + +tryVanilla :: [TyVar] -> [TcType] -> [TyVar] +-- (tryVanilla tvs tys) returns a permutation of tvs. +-- It tries to re-order the tvs so that it exactly +-- matches the [Type], if that is possible +tryVanilla tvs (ty:tys) | Just tv <- tcGetTyVar_maybe ty -- The type is a tyvar + , tv `elem` tvs -- That tyvar is in the list + = tv : tryVanilla (delete tv tvs) tys +tryVanilla tvs tys = tvs -- Fall through case + + +------------------- +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} -Edges in Type/Class decls -~~~~~~~~~~~~~~~~~~~~~~~~~ +%************************************************************************ +%* * +\subsection{Dependency analysis} +%* * +%************************************************************************ + +Validity checking is done once the mutually-recursive knot has been +tied, so we can look at things freely. \begin{code} ----------------------------------------------------- --- 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 - -mk_cls_edges :: RenamedTyClDecl -> Maybe (RenamedTyClDecl, Unique, [Unique]) - -mk_cls_edges decl@(ClassDecl ctxt name _ _ _ _ _ _ _ _) - = Just (decl, getUnique name, map (getUnique . fst) ctxt) -mk_cls_edges other_decl - = Nothing - ----------------------------------------------------- -mk_edges :: RenamedTyClDecl -> (RenamedTyClDecl, Unique, [Unique]) - -mk_edges decl@(TyData _ ctxt name _ condecls derivs _ _) - = (decl, getUnique name, uniqSetToList (get_ctxt ctxt `unionUniqSets` - get_cons condecls `unionUniqSets` - get_deriv derivs)) - -mk_edges decl@(TySynonym name _ rhs _) - = (decl, getUnique name, uniqSetToList (get_ty rhs)) - -mk_edges decl@(ClassDecl ctxt name _ sigs _ _ _ _ _ _) - = (decl, getUnique name, uniqSetToList (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 _ _ ctxt details _) - = get_ctxt ctxt `unionUniqSets` get_con_details details - ----------------------------------------------------- -get_con_details (VanillaCon btys) = unionManyUniqSets (map get_bty btys) -get_con_details (InfixCon bty1 bty2) = unionUniqSets (get_bty bty1) (get_bty bty2) -get_con_details (NewCon ty _) = get_ty ty -get_con_details (RecCon nbtys) = unionManyUniqSets (map (get_bty.snd) nbtys) - ----------------------------------------------------- -get_bty (Banged ty) = get_ty ty -get_bty (Unbanged ty) = get_ty ty -get_bty (Unpacked 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 ty) - = set_name listTyCon_name `unionUniqSets` get_ty ty -get_ty (MonoTupleTy tys boxed) - = set_name (tupleTyCon_name boxed (length tys)) `unionUniqSets` get_tys tys -get_ty (MonoUsgTy _ ty) - = get_ty ty -get_ty (MonoUsgForAllTy _ ty) - = get_ty ty -get_ty (HsForAllTy _ ctxt mty) - = get_ctxt ctxt `unionUniqSets` get_ty mty -get_ty (MonoDictTy name _) - = set_name name - ----------------------------------------------------- -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 (FixSig _) = emptyUniqSet - get_sig other = panic "TcTyClsDecls:get_sig" - ----------------------------------------------------- -set_name name = unitUniqSet (getUnique name) -set_to_bag set = listToBag (uniqSetToList set) -\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) + } + +------------------------- +-- For data types declared with record syntax, we require +-- that each constructor that has a field 'f' +-- (a) has the same result type +-- (b) has the same type for 'f' +-- module alpha conversion of the quantified type variables +-- of the constructor. + +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 -\begin{code} -typeCycleErr, classCycleErr :: [[RenamedTyClDecl]] -> Message + where + syn_ctxt = TySynCtxt name + name = tyConName tc + syn_rhs = synTyConRhs 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` repeat con + -- dataConFieldLabels may return the empty list, which is fine + + -- XXX - autrijus - Make this far more complex to acommodate + -- for different return types. Add res_ty to the mix, + -- comparing them in two steps, all for good error messages. + -- Plan: Use Unify.tcMatchTys to compare the first candidate's + -- result type against other candidates' types (check bothways). + -- If they magically agrees, take the substitution and + -- apply them to the latter ones, and see if they match perfectly. + -- check_fields fields@((first_field_label, field_ty) : other_fields) + check_fields fields@((label, con1) : other_fields) + -- These fields all have the same name, but are from + -- different constructors in the data type + = recoverM (return ()) $ mapM_ checkOne other_fields + -- 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 + where + tvs1 = mkVarSet (dataConTyVars con1) + res1 = dataConResTys con1 + fty1 = dataConFieldType con1 label + + checkOne (_, con2) -- Do it bothways to ensure they are structurally identical + = do { checkFieldCompat label con1 con2 tvs1 res1 res2 fty1 fty2 + ; checkFieldCompat label con2 con1 tvs2 res2 res1 fty2 fty1 } + where + tvs2 = mkVarSet (dataConTyVars con2) + res2 = dataConResTys con2 + fty2 = dataConFieldType con2 label + +checkFieldCompat fld con1 con2 tvs1 res1 res2 fty1 fty2 + = do { checkTc (isJust mb_subst1) (resultTypeMisMatch fld con1 con2) + ; checkTc (isJust mb_subst2) (fieldTypeMisMatch fld con1 con2) } + where + mb_subst1 = tcMatchTys tvs1 res1 res2 + mb_subst2 = tcMatchTyX tvs1 (fromJust mb_subst1) fty1 fty2 + +------------------------------- +checkValidDataCon :: TyCon -> DataCon -> TcM () +checkValidDataCon tc con + = setSrcSpan (srcLocSpan (getSrcLoc 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 + + +------------------------------- +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) -typeCycleErr syn_cycles - = vcat (map (pp_cycle "Cycle in type declarations:") syn_cycles) + -- Check the super-classes + ; checkValidTheta (ClassSCCtxt (className cls)) theta -classCycleErr cls_cycles - = vcat (map (pp_cycle "Cycle in class declarations:") cls_cycles) + -- Check the class operations + ; mappM_ (check_op gla_exts) op_stuff -pp_cycle str decls - = hang (text str) - 4 (vcat (map pp_decl decls)) + -- 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 - pp_decl decl - = hsep [quotes (ppr name), ptext SLIT("at"), ppr (getSrcLoc name)] - where - name = tyClDeclName decl -\end{code} + (tyvars, theta, _, op_stuff) = classBigSig cls + unary = isSingleton tyvars + no_generics = null [() | (_, GenDefMeth) <- op_stuff] + + check_op gla_exts (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 tau) + (badGenericMethodType op_name op_ty) + } + where + op_name = idName sel_id + op_ty = idType sel_id + (_,theta1,tau1) = tcSplitSigmaTy op_ty + (_,theta2,tau2) = tcSplitSigmaTy tau1 + (theta,tau) | gla_exts = (theta1 ++ theta2, tau2) + | otherwise = (theta1, mkPhiTy (tail theta1) tau1) + -- Ugh! The function might have a type like + -- op :: forall a. C a => forall b. (Eq b, Eq a) => tau2 + -- With -fglasgow-exts, we want to allow this, even though the inner + -- forall has an (Eq a) constraint. Whereas in general, each constraint + -- in the context of a for-all must mention at least one quantified + -- type variable. What a mess! + + +--------------------------------------------------------------------- +resultTypeMisMatch field_name con1 con2 + = vcat [sep [ptext SLIT("Constructors") <+> ppr con1 <+> ptext SLIT("and") <+> ppr con2, + ptext SLIT("have a common field") <+> quotes (ppr field_name) <> comma], + nest 2 $ ptext SLIT("but have different result types")] +fieldTypeMisMatch field_name con1 con2 + = sep [ptext SLIT("Constructors") <+> ppr con1 <+> ptext SLIT("and") <+> ppr con2, + ptext SLIT("give different types for field"), quotes (ppr field_name)] + +dataConCtxt con = ptext SLIT("In the definition of data constructor") <+> quotes (ppr con) + +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 + +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 + 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 + +badDataConTyCon data_con + = hang (ptext SLIT("Data constructor") <+> quotes (ppr data_con) <+> + ptext SLIT("returns type") <+> quotes (ppr (dataConTyCon data_con))) + 2 (ptext SLIT("instead of its parent type")) +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")) ] +newtypeConError tycon n + = sep [ptext SLIT("A newtype must have exactly one constructor,"), + nest 2 $ ptext SLIT("but") <+> quotes (ppr tycon) <+> ptext SLIT("has") <+> speakN n ] +newtypeExError con + = sep [ptext SLIT("A newtype constructor cannot have an existential context,"), + nest 2 $ ptext SLIT("but") <+> quotes (ppr con) <+> ptext SLIT("does")] +newtypeFieldErr con_name n_flds + = sep [ptext SLIT("The constructor of a newtype must have exactly one field"), + nest 2 $ ptext SLIT("but") <+> quotes (ppr con_name) <+> ptext SLIT("has") <+> speakN n_flds] + +emptyConDeclsErr tycon + = sep [quotes (ppr tycon) <+> ptext SLIT("has no constructors"), + nest 2 $ ptext SLIT("(-fglasgow-exts permits this)")] + +badBootClassDeclErr = ptext SLIT("Illegal class declaration in hs-boot file") +\end{code}