%
-% (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 HsSyn ( TyClDecl(..), HsConDetails(..), HsTyVarBndr(..),
+ ConDecl(..), Sig(..), , NewOrData(..), ResType(..),
+ tyClDeclTyVars, isSynDecl, hsConArgs,
+ LTyClDecl, tcdName, hsTyVarName, LHsTyVarBndr
)
-import RnHsSyn ( RenamedTyDecl(..), RenamedClassDecl(..), SYN_IE(RenamedHsDecl)
+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 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 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 Maybe ( isJust )
+import Maybes ( expectJust )
+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}
-tcTyAndClassDecls1 :: InstanceMapper
- -> [RenamedHsDecl]
- -> TcM s (TcEnv s)
-
-tcTyAndClassDecls1 inst_mapper decls
- = sortByDependency decls `thenTc` \ groups ->
- tcGroups inst_mapper groups
-
-tcGroups inst_mapper []
- = tcGetEnv `thenNF_Tc` \ env ->
- returnTc env
-
-tcGroups inst_mapper (group:groups)
- = tcGroup inst_mapper group `thenTc` \ new_env ->
- -- Extend the environment using the new tycons and classes
- tcSetEnv new_env $
-
- -- Do the remaining groups
- tcGroups inst_mapper groups
-\end{code}
+%************************************************************************
+%* *
+\subsection{Type checking for type and class declarations}
+%* *
+%************************************************************************
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))) $
+Consider a mutually-recursive group, binding
+a type constructor T and a class C.
- -- TIE THE KNOT
- fixTc ( \ ~(tycons,classes,_) ->
+Step 1: getInitialKind
+ Construct a KindEnv by binding T and C to a kind variable
- -- 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 $
+Step 2: kcTyClDecl
+ In that environment, do a kind check
- -- DEAL WITH TYPE VARIABLES
- tcTyVarScope tyvar_names ( \ tyvars ->
+Step 3: Zonk the kinds
- -- 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
+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
- -- SNAFFLE ENV TO RETURN
- tcGetEnv `thenNF_Tc` \ final_env ->
+Step 5: tcTyClDecl1
+ In this environment, walk over the decls, constructing the TyCons and Classes.
+ This uses in a strict way items (a)-(c) above, which is why they must
+ be constructed in Step 4. Feed the results back to Step 4.
+ For this step, pass the is-recursive flag as the wimp-out flag
+ to tcTyClDecl1.
+
- returnTc (tycons, classes, final_env)
- ) `thenTc` \ (_, _, final_env) ->
+Step 6: Extend environment
+ We extend the type environment with bindings not only for the TyCons and Classes,
+ but also for their "implicit Ids" like data constructors and class selectors
- returnTc final_env
+Step 7: checkValidTyCl
+ For a recursive group only, check all the decls again, just
+ to check all the side conditions on validity. We could not
+ do this before because we were in a mutually recursive knot.
- where
- (tyvar_names, tycon_names_w_arities, class_names) = get_binders decls
- combine do_a do_b
- = do_a `thenTc` \ (a1,a2) ->
- do_b `thenTc` \ (b1,b2) ->
- returnTc (a1 `unionBags` b1, a2 `unionBags` b2)
-\end{code}
+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 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)
-
-tcDecl inst_mapper (ClD decl)
- = tcClassDecl1 inst_mapper decl `thenTc` \ clas ->
- returnTc (emptyBag, unitBag clas)
+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
+ mk_thing (L _ (ClassDecl {tcdLName = L _ name}), ~(AClass cl))
+ = (name, AClass cl)
+ mk_thing (L _ decl, ~(ATyCon tc))
+ = (tcdName decl, ATyCon tc)
\end{code}
-Dependency analysis
-~~~~~~~~~~~~~~~~~~~
-\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)
- 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)
+%************************************************************************
+%* *
+ Kind checking
+%* *
+%************************************************************************
-
+We need to kind check all types in the mutually recursive group
+before we know the kind of the type variables. For example:
-bag_acyclic (AcyclicSCC scc) = unitBag scc
-bag_acyclic (CyclicSCC sccs) = sccs
+class C a where
+ op :: D b => a -> b -> b
-is_syn_decl (TyD (TySynonym _ _ _ _)) = True
-is_syn_decl _ = False
+class D c where
+ bop :: (Monad c) => ...
-is_ty_cls_decl (TyD _) = True
-is_ty_cls_decl (ClD _) = True
-is_ty_cls_decl other = False
+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.
-is_cls_decl (ClD _) = True
-is_cls_decl other = False
+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.
-fmt_decl decl
- = (ppr PprForUser name, getSrcLoc name)
+\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)
+-- 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
- name = hsDeclName decl
+ 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
+ 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}
-Edges in Type/Class decls
-~~~~~~~~~~~~~~~~~~~~~~~~~
+
+%************************************************************************
+%* *
+\subsection{Type checking}
+%* *
+%************************************************************************
+
\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 tv)
- = emptyUniqSet
-get_ty (MonoTyApp name tys)
- = (if isTvOcc (nameOccName name) then emptyUniqSet else set_name name)
- `unionUniqSets` get_tys tys
-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)
+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)
+
+ -- 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}
+%************************************************************************
+%* *
+\subsection{Dependency analysis}
+%* *
+%************************************************************************
-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.
+Validity checking is done once the mutually-recursive knot has been
+tied, so we can look at things freely.
-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:
+\begin{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
-class C a where
- op :: D b => a -> b -> b
+ 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 (expectJust "checkFieldCompat" 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
-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.
+-------------------------------
+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)
-\begin{code}
-get_binders :: Bag RenamedHsDecl
- -> ([HsTyVar Name], -- TyVars; no dups
- [(Name, Maybe Arity)], -- Tycons; no dups; arities for synonyms
- [Name]) -- Classes; no dups
+ -- Check the super-classes
+ ; checkValidTheta (ClassSCCtxt (className cls)) theta
+
+ -- Check the class operations
+ ; mappM_ (check_op gla_exts) op_stuff
-get_binders decls = (bagToList tyvars, bagToList tycons, bagToList classes)
+ -- 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, 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}
+ (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 = [] })
-\begin{code}
-typeCycleErr syn_cycles sty
- = ppAboves (map (pp_cycle sty "Cycle in type declarations ...") syn_cycles)
+sortLocated :: [Located a] -> [Located a]
+sortLocated things = sortLe le things
+ where
+ le (L l1 _) (L l2 _) = l1 <= l2
-classCycleErr cls_cycles sty
- = ppAboves (map (pp_cycle sty "Cycle in class declarations ...") cls_cycles)
+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"))
-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")) ]
+
+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}