X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcTyClsDecls.lhs;h=45da66704efb10d5f289b92c0d73f04bb10d45db;hb=3a223cd2811d46295048b3a2dab11403ca291b20;hp=89e6bfe2a60fc68119c91954844e87fb27168482;hpb=1c3601593186639f1086bc402582ff56fd3fe9f8;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcTyClsDecls.lhs b/ghc/compiler/typecheck/TcTyClsDecls.lhs index 89e6bfe..45da667 100644 --- a/ghc/compiler/typecheck/TcTyClsDecls.lhs +++ b/ghc/compiler/typecheck/TcTyClsDecls.lhs @@ -10,45 +10,46 @@ module TcTyClsDecls ( #include "HsVersions.h" -import HsSyn ( HsDecl(..), TyClDecl(..), - HsType(..), HsTyVarBndr, - ConDecl(..), ConDetails(..), - Sig(..), HsPred(..), HsTupCon(..), - tyClDeclName, hsTyVarNames, isClassDecl, isSynDecl, isClassOpSig, getBangType +import HsSyn ( TyClDecl(..), + ConDecl(..), Sig(..), HsPred(..), + tyClDeclName, hsTyVarNames, tyClDeclTyVars, + isTypeOrClassDecl, isClassDecl, isSynDecl, isClassOpSig ) -import RnHsSyn ( RenamedHsDecl, RenamedTyClDecl, listTyCon_name ) +import RnHsSyn ( RenamedTyClDecl, tyClDeclFVs ) +import RnEnv ( lookupSysName ) import BasicTypes ( RecFlag(..), NewOrData(..) ) +import HscTypes ( implicitTyThings ) -import TcMonad -import TcEnv ( ValueEnv, TyThing(..), TyThingDetails(..), tyThingKind, - tcExtendTypeEnv, tcExtendKindEnv, tcLookupTy - ) -import TcTyDecls ( tcTyDecl1, kcConDetails, mkNewTyConRep ) +import TcRnMonad +import TcEnv ( TcTyThing(..), TyThing(..), TyThingDetails(..), + tcExtendKindEnv, tcLookup, tcLookupGlobal, tcExtendGlobalEnv, + isLocalThing ) +import TcTyDecls ( tcTyDecl, kcConDetails ) import TcClassDcl ( tcClassDecl1 ) -import TcMonoType ( kcHsTyVars, kcHsType, kcHsBoxedSigType, kcHsContext, mkTyClTyVars ) -import TcType ( TcKind, newKindVar, zonkKindEnv ) - -import TcUnify ( unifyKind ) import TcInstDcls ( tcAddDeclCtxt ) -import Type ( Kind, mkArrowKind, boxedTypeKind, zipFunTys ) +import TcMonoType ( kcHsTyVars, kcHsType, kcHsLiftedSigType, kcHsContext, mkTyClTyVars ) +import TcMType ( newKindVar, zonkKindEnv, checkValidTyCon, checkValidClass ) +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(..), mkSynTyCon, mkAlgTyConRep, mkClassTyCon ) -import DataCon ( isNullaryDataCon ) +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 OccName ( mkClassTyConOcc ) import FiniteMap import Digraph ( stronglyConnComp, SCC(..) ) -import Name ( Name, NamedThing(..), NameEnv, getSrcLoc, isTvOcc, nameOccName, - mkNameEnv, lookupNameEnv_NF - ) +import Name ( Name ) +import NameEnv +import NameSet import Outputable -import Maybes ( mapMaybe, catMaybes ) -import UniqSet ( emptyUniqSet, unitUniqSet, unionUniqSets, - unionManyUniqSets, uniqSetToList ) -import ErrUtils ( Message ) -import Unique ( Unique, Uniquable(..) ) -import HsDecls ( fromClassDeclNameList ) -import Generics ( mkTyConGenInfo ) +import Maybes ( mapMaybe, orElse, catMaybes ) \end{code} @@ -61,22 +62,22 @@ import Generics ( mkTyConGenInfo ) The main function ~~~~~~~~~~~~~~~~~ \begin{code} -tcTyAndClassDecls :: ValueEnv -- Knot tying stuff - -> [RenamedHsDecl] - -> TcM TcEnv - -tcTyAndClassDecls unf_env decls - = sortByDependency decls `thenTc` \ groups -> - tcGroups unf_env groups - -tcGroups unf_env [] - = tcGetEnv `thenNF_Tc` \ env -> - returnTc env - -tcGroups unf_env (group:groups) - = tcGroup unf_env group `thenTc` \ env -> - tcSetEnv env $ - tcGroups unf_env groups +tcTyAndClassDecls :: [RenamedTyClDecl] + -> TcM TcGblEnv -- Returns extended environment + +tcTyAndClassDecls decls + = do { edge_map <- mkEdgeMap tc_decls ; + let { edges = mkEdges edge_map tc_decls } ; + tcGroups edge_map (stronglyConnComp edges) } + where + tc_decls = filter isTypeOrClassDecl decls + +tcGroups edge_map [] = getGblEnv + +tcGroups edge_map (group:groups) + = tcGroup edge_map group `thenM` \ env -> + setGblEnv env $ + tcGroups edge_map groups \end{code} Dealing with a group @@ -104,66 +105,107 @@ Step 4: buildTyConOrClass 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. + be constructed in Step 4. Feed the results back to Step 4. + For this step, pass the is-recursive flag as the wimp-out flag + to tcTyClDecl1. + +Step 6: Extend environment + We extend the type environment with bindings not only for the TyCons and Classes, + but also for their "implicit Ids" like data constructors and class selectors + +Step 7: checkValidTyCl + For a recursive group only, check all the decls again, just + to check all the side conditions on validity. We could not + do this before because we were in a mutually recursive knot. + + The knot-tying parameters: @rec_details_list@ is an alist mapping @Name@s to @TyThing@s. @rec_vrcs@ is a finite map from @Name@s to @ArgVrcs@s. \begin{code} -tcGroup :: ValueEnv -> SCC RenamedTyClDecl -> TcM TcEnv -tcGroup unf_env scc +tcGroup :: EdgeMap -> SCC RenamedTyClDecl + -> TcM TcGblEnv -- Input env extended by types and classes + -- and their implicit Ids,DataCons + +tcGroup edge_map scc = -- Step 1 - mapNF_Tc getInitialKind decls `thenNF_Tc` \ initial_kinds -> + mappM getInitialKind decls `thenM` \ initial_kinds -> -- Step 2 - tcExtendKindEnv initial_kinds (mapTc kcTyClDecl decls) `thenTc_` + tcExtendKindEnv initial_kinds (mappM kcTyClDecl decls) `thenM_` -- Step 3 - zonkKindEnv initial_kinds `thenNF_Tc` \ final_kinds -> + 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 edge_map scc) `thenM` \ is_rec_tycon -> -- Tie the knot - fixTc ( \ ~(rec_details_list, _) -> + traceTc (text "starting" <+> ppr final_kinds) `thenM_` + fixM ( \ ~(rec_details_list, _, _) -> -- Step 4 let kind_env = mkNameEnv final_kinds rec_details = mkNameEnv rec_details_list - tyclss, all_tyclss :: [(Name, TyThing)] - tyclss = map (buildTyConOrClass is_rec kind_env rec_vrcs rec_details) decls + -- Calculate variances, and feed into buildTyConOrClass + rec_vrcs = calcTyConArgVrcs [tc | ATyCon tc <- tyclss] - -- Add the tycons that come from the classes - -- We want them in the environment because - -- they are mentioned in interface files - all_tyclss = [ (getName tycon, ATyCon tycon) | (_, AClass clas) <- tyclss, - let tycon = classTyCon clas - ] ++ tyclss + build_one = buildTyConOrClass is_rec_tycon kind_env + rec_vrcs rec_details + tyclss = map build_one decls - -- Calculate variances, and (yes!) feed back into buildTyConOrClass. - rec_vrcs = calcTyConArgVrcs [tc | (_, ATyCon tc) <- all_tyclss] in -- Step 5 - tcExtendGlobalEnv all_tyclss $ - mapTc (tcTyClDecl1 unf_env) decls `thenTc` \ tycls_details -> - tcGetEnv `thenNF_Tc` \ env -> - returnTc (tycls_details, env) - ) `thenTc` \ (_, env) -> - returnTc env - where - is_rec = case scc of - AcyclicSCC _ -> NonRecursive - CyclicSCC _ -> Recursive + -- 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 + setGblEnv env $ + + traceTc (text "ready for validity check") `thenM_` + getModule `thenM` \ mod -> + mappM_ (checkValidTyCl mod) decls `thenM_` + traceTc (text "done") `thenM_` + + let -- Add the tycons that come from the classes + -- We want them in the environment because + -- they are mentioned in interface files + implicit_things = implicitTyThings tyclss + in + traceTc ((text "Adding" <+> ppr tyclss) $$ (text "and" <+> ppr implicit_things)) `thenM_` + tcExtendGlobalEnv implicit_things getGblEnv + where decls = case scc of AcyclicSCC decl -> [decl] CyclicSCC decls -> decls -tcTyClDecl1 unf_env decl - = tcAddDeclCtxt decl $ - if isClassDecl decl then - tcClassDecl1 unf_env decl +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 - tcTyDecl1 decl + tcAddDeclCtxt decl $ + case thing of + ATyCon tc -> checkValidTyCon tc + AClass cl -> checkValidClass cl \end{code} @@ -174,19 +216,11 @@ tcTyClDecl1 unf_env decl %************************************************************************ \begin{code} -getInitialKind :: RenamedTyClDecl -> NF_TcM (Name, TcKind) -getInitialKind (TySynonym name tyvars _ _) - = kcHsTyVars tyvars `thenNF_Tc` \ arg_kinds -> - newKindVar `thenNF_Tc` \ result_kind -> - returnNF_Tc (name, mk_kind arg_kinds result_kind) - -getInitialKind (TyData _ _ name tyvars _ _ _ _ _ _ _) - = kcHsTyVars tyvars `thenNF_Tc` \ arg_kinds -> - returnNF_Tc (name, mk_kind arg_kinds boxedTypeKind) - -getInitialKind (ClassDecl _ name tyvars _ _ _ _ _ _ ) - = kcHsTyVars tyvars `thenNF_Tc` \ arg_kinds -> - returnNF_Tc (name, mk_kind arg_kinds boxedTypeKind) +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} @@ -214,54 +248,51 @@ Monad c in bop's type signature means that D must have kind Type->Type. \begin{code} kcTyClDecl :: RenamedTyClDecl -> TcM () -kcTyClDecl decl@(TySynonym tycon_name hs_tyvars rhs loc) - = tcAddDeclCtxt decl $ - kcTyClDeclBody tycon_name hs_tyvars $ \ result_kind -> - kcHsType rhs `thenTc` \ rhs_kind -> +kcTyClDecl decl@(TySynonym {tcdSynRhs = rhs}) + = kcTyClDeclBody decl $ \ result_kind -> + kcHsType rhs `thenM` \ rhs_kind -> unifyKind result_kind rhs_kind -kcTyClDecl decl@(TyData _ context tycon_name hs_tyvars con_decls _ _ _ loc _ _) - = tcAddDeclCtxt decl $ - kcTyClDeclBody tycon_name hs_tyvars $ \ result_kind -> - kcHsContext context `thenTc_` - mapTc_ kc_con_decl con_decls +kcTyClDecl (ForeignType {}) = returnM () + +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) where - kc_con_decl (ConDecl _ _ ex_tvs ex_ctxt details loc) - = tcAddSrcLoc loc $ - kcHsTyVars ex_tvs `thenNF_Tc` \ kind_env -> + kc_con_decl (ConDecl _ ex_tvs ex_ctxt details loc) + = kcHsTyVars ex_tvs `thenM` \ kind_env -> tcExtendKindEnv kind_env $ - kcConDetails ex_ctxt details - -kcTyClDecl decl@(ClassDecl context class_name - hs_tyvars fundeps class_sigs - _ _ _ loc) - = tcAddDeclCtxt decl $ - kcTyClDeclBody class_name hs_tyvars $ \ result_kind -> - kcHsContext context `thenTc_` - mapTc_ kc_sig (filter isClassOpSig class_sigs) + 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) where - kc_sig (ClassOpSig _ _ op_ty loc) = tcAddSrcLoc loc (kcHsBoxedSigType op_ty) + kc_sig (ClassOpSig _ _ op_ty loc) = kcHsLiftedSigType op_ty -kcTyClDeclBody :: Name -> [HsTyVarBndr Name] -- Kind of the tycon/cls and its tyvars - -> (Kind -> TcM a) -- Thing inside - -> TcM a +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 -kcTyClDeclBody tc_name hs_tyvars thing_inside - = tcLookupTy tc_name `thenNF_Tc` \ tc -> +kcTyClDeclBody decl thing_inside + = tcAddDeclCtxt decl $ + tcLookup (tcdName decl) `thenM` \ thing -> let - kind = case tc of - ATyCon tc -> tyConKind tc - AClass cl -> tyConKind (classTyCon cl) + 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 hs_tyvars) kind + (tyvars_w_kinds, result_kind) = zipFunTys (hsTyVarNames (tyClDeclTyVars decl)) kind in tcExtendKindEnv tyvars_w_kinds (thing_inside result_kind) \end{code} + %************************************************************************ %* * \subsection{Step 4: Building the tycon/class} @@ -270,15 +301,14 @@ kcTyClDeclBody tc_name hs_tyvars thing_inside \begin{code} buildTyConOrClass - :: RecFlag -> NameEnv Kind + :: (Name -> AlgTyConFlavour -> RecFlag) -- Whether it's recursive + -> NameEnv Kind -> FiniteMap TyCon ArgVrcs -> NameEnv TyThingDetails - -> RenamedTyClDecl -> (Name, TyThing) - -- Can't fail; the only reason it's in the monad - -- is so it can zonk the kinds + -> RenamedTyClDecl -> TyThing -buildTyConOrClass is_rec kenv rec_vrcs rec_details - (TySynonym tycon_name tyvar_names rhs src_loc) - = (tycon_name, ATyCon tycon) +buildTyConOrClass rec_tycon kenv rec_vrcs rec_details + (TySynonym {tcdName = tycon_name, tcdTyVars = tyvar_names}) + = ATyCon tycon where tycon = mkSynTyCon tycon_name tycon_kind arity tyvars rhs_ty argvrcs tycon_kind = lookupNameEnv_NF kenv tycon_name @@ -287,34 +317,44 @@ buildTyConOrClass is_rec kenv rec_vrcs rec_details SynTyDetails rhs_ty = lookupNameEnv_NF rec_details tycon_name argvrcs = lookupWithDefaultFM rec_vrcs bogusVrcs tycon -buildTyConOrClass is_rec kenv rec_vrcs rec_details - (TyData data_or_new context tycon_name tyvar_names _ nconstrs _ _ src_loc name1 name2) - = (tycon_name, ATyCon tycon) +buildTyConOrClass rec_tycon kenv rec_vrcs rec_details + (TyData {tcdND = data_or_new, tcdName = tycon_name, + tcdTyVars = tyvar_names}) + = ATyCon tycon where - tycon = mkAlgTyConRep tycon_name tycon_kind tyvars ctxt argvrcs - data_cons nconstrs - derived_classes - flavour is_rec gen_info - gen_info = mkTyConGenInfo tycon name1 name2 + 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 derived_classes = lookupNameEnv_NF rec_details tycon_name + 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 isNullaryDataCon data_cons -> EnumTyCon - | otherwise -> DataTyCon - -buildTyConOrClass is_rec kenv rec_vrcs rec_details - (ClassDecl context class_name - tyvar_names fundeps class_sigs def_methods pragmas - name_list src_loc) - = (class_name, AClass clas) + 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 where - (tycon_name, _, _, _) = fromClassDeclNameList name_list clas = mkClass class_name tyvars fds sc_theta sc_sel_ids op_items tycon @@ -323,16 +363,26 @@ buildTyConOrClass is_rec kenv rec_vrcs rec_details argvrcs dict_con clas -- Yes! It's a dictionary flavour - - ClassDetails sc_theta sc_sel_ids op_items dict_con = lookupNameEnv_NF rec_details class_name + (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 - n_fields = length sc_sel_ids + length op_items - flavour | n_fields == 1 = NewTyCon (mkNewTyConRep tycon) - | otherwise = DataTyCon + 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 @@ -345,6 +395,40 @@ buildTyConOrClass is_rec kenv rec_vrcs rec_details 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) +\end{code} %************************************************************************ %* * @@ -355,115 +439,105 @@ bogusVrcs = panic "Bogus tycon arg variances" Dependency analysis ~~~~~~~~~~~~~~~~~~~ \begin{code} -sortByDependency :: [RenamedHsDecl] -> TcM [SCC RenamedTyClDecl] -sortByDependency decls +checkLoops :: EdgeMap -> SCC RenamedTyClDecl + -> TcM (Name -> AlgTyConFlavour -> RecFlag) +-- Check for illegal loops in a single strongly-connected component +-- 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 edge_map (AcyclicSCC _) + = returnM (\ _ _ -> NonRecursive) + +checkLoops edge_map (CyclicSCC decls) = let -- CHECK FOR CLASS CYCLES - cls_sccs = stronglyConnComp (mapMaybe mk_cls_edges tycl_decls) - cls_cycles = [ decls | CyclicSCC decls <- cls_sccs] + cls_edges = mapMaybe mkClassEdges decls + cls_cycles = findCycles cls_edges in - checkTc (null cls_cycles) (classCycleErr cls_cycles) `thenTc_` + mapM_ (cycleErr "class") cls_cycles `thenM_` let -- CHECK FOR SYNONYM CYCLES - syn_sccs = stronglyConnComp (filter is_syn_decl edges) - syn_cycles = [ decls | CyclicSCC decls <- syn_sccs] - + syn_edges = mkEdges edge_map (filter isSynDecl decls) + syn_cycles = findCycles syn_edges in - checkTc (null syn_cycles) (typeCycleErr syn_cycles) `thenTc_` + mapM_ (cycleErr "type synonym") syn_cycles `thenM_` - -- 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 - - is_syn_decl (d, _, _) = isSynDecl d -\end{code} - -Edges in Type/Class decls -~~~~~~~~~~~~~~~~~~~~~~~~~ - -\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 (catMaybes (map get_clas 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 (catMaybes (map get_clas ctxt))) -get_clas (HsPClass clas _) = Just clas -get_clas _ = Nothing - ----------------------------------------------------- -get_deriv Nothing = emptyUniqSet -get_deriv (Just clss) = unionManyUniqSets (map set_name clss) - ----------------------------------------------------- -get_cons cons = unionManyUniqSets (map get_con cons) + let -- CHECK FOR NEWTYPE CYCLES + newtype_edges = mkEdges edge_map (filter is_nt_cycle_decl decls) + newtype_cycles = findCycles newtype_edges + rec_newtypes = mkNameSet [tcdName d | ds <- newtype_cycles, d <- ds] ----------------------------------------------------- -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 (RecCon nbtys) = unionManyUniqSets (map (get_bty.snd) nbtys) + rec_tycon name (NewTyCon _) + | name `elemNameSet` rec_newtypes = Recursive + | otherwise = NonRecursive + rec_tycon name other_flavour = Recursive + in + returnM rec_tycon ---------------------------------------------------- -get_bty bty = get_ty (getBangType bty) +-- 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 ---------------------------------------------------- -get_ty (HsTyVar name) | isTvOcc (nameOccName name) = emptyUniqSet - | otherwise = set_name name -get_ty (HsAppTy ty1 ty2) = unionUniqSets (get_ty ty1) (get_ty ty2) -get_ty (HsFunTy ty1 ty2) = unionUniqSets (get_ty ty1) (get_ty ty2) -get_ty (HsListTy ty) = set_name listTyCon_name `unionUniqSets` get_ty ty -get_ty (HsTupleTy (HsTupCon n _) tys) = set_name n `unionUniqSets` get_tys tys -get_ty (HsUsgTy _ ty) = get_ty ty -get_ty (HsUsgForAllTy _ ty) = get_ty ty -get_ty (HsForAllTy _ ctxt mty) = get_ctxt ctxt `unionUniqSets` get_ty mty -get_ty (HsPredTy (HsPClass name _)) = set_name name -get_ty (HsPredTy (HsPIParam _ _)) = emptyUniqSet -- I think +findCycles edges = [ ds | CyclicSCC ds <- stronglyConnComp edges] ---------------------------------------------------- -get_tys tys = unionManyUniqSets (map get_ty tys) +-- Building edges for SCC analysis +-- +-- When building the edges, we treat the 'main name' of the declaration as the +-- key for the node, but when dealing with External Core we may come across +-- references to one of the implicit names for the declaration. For example: +-- class Eq a where .... +-- data :TSig a = :TSig (:TEq a) .... +-- The first decl is sucked in from an interface file; the second +-- is in an External Core file, generated from a class decl for Sig. +-- We have to recognise that the reference to :TEq represents a +-- dependency on the class Eq declaration, else the SCC stuff won't work right. +-- +-- This complication can only happen when consuming an External Core file +-- +-- Solution: keep an "EdgeMap" (bad name) that maps :TEq -> Eq. +-- Don't worry about data constructors, because we're only building +-- SCCs for type and class declarations here. So the tiresome mapping +-- is need only to map [class tycon -> class] + +type EdgeMap = NameEnv Name + +mkEdgeMap :: [RenamedTyClDecl] -> TcM EdgeMap +mkEdgeMap decls = do { mb_pairs <- mapM mk_mb_pair decls ; + return (mkNameEnv (catMaybes mb_pairs)) } + where + mk_mb_pair (ClassDecl { tcdName = cls_name }) + = do { tc_name <- lookupSysName cls_name mkClassTyConOcc ; + return (Just (tc_name, cls_name)) } + mk_mb_pair other = return Nothing + +mkEdges :: EdgeMap -> [RenamedTyClDecl] -> [(RenamedTyClDecl, Name, [Name])] +-- We use the EdgeMap to map any implicit names to +-- the 'main name' for the declaration +mkEdges edge_map decls + = [ (decl, tyClDeclName decl, get_refs decl) | decl <- decls ] + where + get_refs decl = [ lookupNameEnv edge_map n `orElse` n + | n <- nameSetToList (tyClDeclFVs decl) ] ---------------------------------------------------- -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" +-- 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 ----------------------------------------------------- -set_name name = unitUniqSet (getUnique name) +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} @@ -474,21 +548,17 @@ set_name name = unitUniqSet (getUnique name) %************************************************************************ \begin{code} -typeCycleErr, classCycleErr :: [[RenamedTyClDecl]] -> Message - -typeCycleErr syn_cycles - = vcat (map (pp_cycle "Cycle in type declarations:") syn_cycles) +cycleErr :: String -> [RenamedTyClDecl] -> TcM () -classCycleErr cls_cycles - = vcat (map (pp_cycle "Cycle in class declarations:") cls_cycles) +cycleErr kind_of_decl decls + = addErrAt loc (ppr_cycle kind_of_decl decls) + where + loc = tcdLoc (head decls) -pp_cycle str decls - = hang (text str) +ppr_cycle kind_of_decl decls + = hang (ptext SLIT("Cycle in") <+> text kind_of_decl <+> ptext SLIT("declarations:")) 4 (vcat (map pp_decl decls)) where - pp_decl decl - = hsep [quotes (ppr name), ptext SLIT("at"), ppr (getSrcLoc name)] - where - name = tyClDeclName decl - + pp_decl decl = hsep [quotes (ppr (tcdName decl)), + ptext SLIT("at"), ppr (tcdLoc decl)] \end{code}