X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcTyClsDecls.lhs;h=404d4cb3db66cedeb9f9973f1f8702c6de5bbcb1;hb=4ef18ea237ee070678970dbdd49714014dd9efbf;hp=db58f67496429a30d28e54fb64b146637f2e371c;hpb=2ecf1c9f639dc75f1078e88c2e551116923f742a;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcTyClsDecls.lhs b/ghc/compiler/typecheck/TcTyClsDecls.lhs index db58f67..404d4cb 100644 --- a/ghc/compiler/typecheck/TcTyClsDecls.lhs +++ b/ghc/compiler/typecheck/TcTyClsDecls.lhs @@ -10,45 +10,44 @@ module TcTyClsDecls ( #include "HsVersions.h" -import HsSyn ( HsDecl(..), TyClDecl(..), - HsTyVarBndr, - ConDecl(..), - Sig(..), HsPred(..), - tyClDeclName, hsTyVarNames, - isIfaceSigDecl, isClassDecl, isSynDecl, isClassOpSig +import HsSyn ( TyClDecl(..), + ConDecl(..), Sig(..), HsPred(..), + tyClDeclName, hsTyVarNames, tyClDeclTyVars, + isTypeOrClassDecl, isClassDecl, isSynDecl, isClassOpSig ) -import RnHsSyn ( RenamedHsDecl, RenamedTyClDecl, tyClDeclFVs ) +import RnHsSyn ( RenamedTyClDecl, tyClDeclFVs ) import BasicTypes ( RecFlag(..), NewOrData(..) ) +import HscTypes ( implicitTyThingIds ) -import TcMonad -import TcEnv ( TcEnv, TcTyThing(..), TyThing(..), TyThingDetails(..), - tcExtendKindEnv, tcLookup, tcExtendGlobalEnv ) -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, tyConKind, 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 FiniteMap import Digraph ( stronglyConnComp, SCC(..) ) -import Name ( Name, NamedThing(..), NameEnv, getSrcLoc, - mkNameEnv, lookupNameEnv_NF, isTyVarName - ) +import Name ( Name ) +import NameEnv import NameSet import Outputable import Maybes ( mapMaybe ) -import ErrUtils ( Message ) -import HsDecls ( getClassDeclSysNames ) -import Generics ( mkTyConGenInfo ) -import CmdLineOpts ( DynFlags ) \end{code} @@ -61,22 +60,23 @@ import CmdLineOpts ( DynFlags ) The main function ~~~~~~~~~~~~~~~~~ \begin{code} -tcTyAndClassDecls :: TcEnv -- 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 [TyThing] -- Returns newly defined things: + -- types, classes and implicit Ids + +tcTyAndClassDecls decls + = tcGroups (stronglyConnComp edges) + where + edges = map mkEdges (filter isTypeOrClassDecl decls) + +tcGroups [] + = returnM [] + +tcGroups (group:groups) + = tcGroup group `thenM` \ (env, new_things1) -> + setGblEnv env $ + tcGroups groups `thenM` \ new_things2 -> + returnM (new_things1 ++ new_things2) \end{code} Dealing with a group @@ -104,68 +104,110 @@ 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 :: TcEnv -> SCC RenamedTyClDecl -> TcM TcEnv -tcGroup unf_env scc - = getDOptsTc `thenTc` \ dflags -> - -- Step 1 - mapNF_Tc getInitialKind decls `thenNF_Tc` \ initial_kinds -> +tcGroup :: SCC RenamedTyClDecl + -> TcM (TcGblEnv, -- Input env extended by types and classes only + [TyThing]) -- Things defined by this group + +tcGroup scc + = -- Step 1 + mappM getInitialKind decls `thenM` \ initial_kinds -> -- Step 2 - tcExtendKindEnv initial_kinds (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 scc) `thenM` \ is_rec_tycon -> -- Tie the knot - fixTc ( \ ~(rec_details_list, _) -> + traceTc (text "starting" <+> ppr final_kinds) `thenM_` + fixM ( \ ~(rec_details_list, _, rec_all_tyclss) -> -- Step 4 let kind_env = mkNameEnv final_kinds rec_details = mkNameEnv rec_details_list - tyclss, all_tyclss :: [(Name, TyThing)] - tyclss = map (buildTyConOrClass dflags is_rec kind_env - rec_vrcs rec_details) decls + -- Calculate variances, and feed into buildTyConOrClass + rec_vrcs = calcTyConArgVrcs [tc | ATyCon tc <- rec_all_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 + traceTc (text "ready for validity check") `thenM_` + getModule `thenM` \ mod -> + setGblEnv env ( + 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_tycons, implicit_ids, all_tyclss :: [TyThing] + implicit_tycons = [ATyCon (classTyCon clas) | AClass clas <- tyclss] + all_tyclss = implicit_tycons ++ tyclss + implicit_ids = [AnId id | id <- implicitTyThingIds all_tyclss] + new_things = implicit_ids ++ all_tyclss + in + returnM (env, new_things) + 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} @@ -176,19 +218,11 @@ 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} @@ -216,42 +250,37 @@ 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 - = tcLookup tc_name `thenNF_Tc` \ thing -> +kcTyClDeclBody decl thing_inside + = tcAddDeclCtxt decl $ + tcLookup (tcdName decl) `thenM` \ thing -> let kind = case thing of AGlobal (ATyCon tc) -> tyConKind tc @@ -259,12 +288,13 @@ kcTyClDeclBody tc_name hs_tyvars thing_inside 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} @@ -273,16 +303,14 @@ kcTyClDeclBody tc_name hs_tyvars thing_inside \begin{code} buildTyConOrClass - :: DynFlags - -> 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 dflags 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 @@ -291,34 +319,44 @@ buildTyConOrClass dflags is_rec kenv rec_vrcs rec_details SynTyDetails rhs_ty = lookupNameEnv_NF rec_details tycon_name argvrcs = lookupWithDefaultFM rec_vrcs bogusVrcs tycon -buildTyConOrClass dflags 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 dflags 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 dflags is_rec kenv rec_vrcs rec_details - (ClassDecl context class_name - tyvar_names fundeps class_sigs def_methods - 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, _, _, _) = getClassDeclSysNames name_list clas = mkClass class_name tyvars fds sc_theta sc_sel_ids op_items tycon @@ -327,16 +365,26 @@ buildTyConOrClass dflags 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 @@ -349,6 +397,38 @@ buildTyConOrClass dflags 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 +-- +-- 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} %************************************************************************ %* * @@ -359,42 +439,60 @@ bogusVrcs = panic "Bogus tycon arg variances" Dependency analysis ~~~~~~~~~~~~~~~~~~~ \begin{code} -sortByDependency :: [RenamedHsDecl] -> TcM [SCC RenamedTyClDecl] -sortByDependency decls +checkLoops :: SCC RenamedTyClDecl + -> TcM (Name -> AlgTyConFlavour -> RecFlag) +-- Check for illegal loops, +-- a) type synonyms +-- b) superclass hierarchy +-- +-- Also return a function that says which tycons are recursive. +-- Remember: +-- a newtype is recursive if it is part of a recursive +-- group consisting only of newtype and synonyms + +checkLoops (AcyclicSCC _) + = returnM (\ _ _ -> NonRecursive) + +checkLoops (CyclicSCC decls) = let -- CHECK FOR CLASS CYCLES - cls_sccs = stronglyConnComp (mapMaybe mkClassEdges 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 = map mkEdges (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 + let -- CHECK FOR NEWTYPE CYCLES + newtype_edges = map mkEdges (filter is_nt_cycle_decl decls) + newtype_cycles = findCycles newtype_edges + rec_newtypes = mkNameSet [tcdName d | ds <- newtype_cycles, d <- ds] + + rec_tycon name (NewTyCon _) + | name `elemNameSet` rec_newtypes = Recursive + | otherwise = NonRecursive + rec_tycon name other_flavour = Recursive in - returnTc decl_sccs - where - tycl_decls = [d | TyClD d <- decls, not (isIfaceSigDecl d)] - edges = map mkEdges tycl_decls - - is_syn_decl (d, _, _) = isSynDecl d -\end{code} + returnM rec_tycon + +---------------------------------------------------- +-- A class with one op and no superclasses, or vice versa, +-- is treated just like a newtype. +-- It's a bit unclean that this test is repeated in buildTyConOrClass +is_nt_cycle_decl (TySynonym {}) = True +is_nt_cycle_decl (TyData {tcdND = NewType}) = True +is_nt_cycle_decl (ClassDecl {tcdCtxt = ctxt, tcdSigs = sigs}) = length ctxt + length sigs == 1 +is_nt_cycle_decl other = False -Edges in Type/Class decls -~~~~~~~~~~~~~~~~~~~~~~~~~ +---------------------------------------------------- +findCycles edges = [ ds | CyclicSCC ds <- stronglyConnComp edges] -\begin{code} -tyClDeclFTVs :: RenamedTyClDecl -> [Name] -tyClDeclFTVs d = foldNameSet add [] (tyClDeclFVs d) - where - add n fvs | isTyVarName n = fvs - | otherwise = n : fvs +---------------------------------------------------- +mkEdges :: RenamedTyClDecl -> (RenamedTyClDecl, Name, [Name]) +mkEdges decl = (decl, tyClDeclName decl, nameSetToList (tyClDeclFVs decl)) ---------------------------------------------------- -- mk_cls_edges looks only at the context of class decls @@ -402,13 +500,8 @@ tyClDeclFTVs d = foldNameSet add [] (tyClDeclFVs d) -- superclass hierarchy mkClassEdges :: RenamedTyClDecl -> Maybe (RenamedTyClDecl, Name, [Name]) - -mkClassEdges decl@(ClassDecl ctxt name _ _ _ _ _ _) = Just (decl, name, [c | HsPClass c _ <- ctxt]) -mkClassEdges other_decl = Nothing - ----------------------------------------------------- -mkEdges :: RenamedTyClDecl -> (RenamedTyClDecl, Name, [Name]) -mkEdges decl = (decl, tyClDeclName decl, tyClDeclFTVs decl) +mkClassEdges decl@(ClassDecl {tcdCtxt = ctxt, tcdName = name}) = Just (decl, name, [c | HsClassP c _ <- ctxt]) +mkClassEdges other_decl = Nothing \end{code} @@ -419,21 +512,17 @@ mkEdges decl = (decl, tyClDeclName decl, tyClDeclFTVs decl) %************************************************************************ \begin{code} -typeCycleErr, classCycleErr :: [[RenamedTyClDecl]] -> Message +cycleErr :: String -> [RenamedTyClDecl] -> TcM () -typeCycleErr syn_cycles - = vcat (map (pp_cycle "Cycle in type declarations:") syn_cycles) - -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}