X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcTyClsDecls.lhs;h=97aa4c762638ece86b0b5d35b60c02d7ad48c99d;hb=c86e9006fbdc9cb229080dd6a64ce462e9e460af;hp=805c700e36833756049af48ed4bf2683afb94f4c;hpb=e3defabc698eb976504f750eee1258fe400a8352;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcTyClsDecls.lhs b/ghc/compiler/typecheck/TcTyClsDecls.lhs index 805c700..97aa4c7 100644 --- a/ghc/compiler/typecheck/TcTyClsDecls.lhs +++ b/ghc/compiler/typecheck/TcTyClsDecls.lhs @@ -10,43 +10,46 @@ module TcTyClsDecls ( #include "HsVersions.h" -import CmdLineOpts ( DynFlags, DynFlag(..), dopt ) import HsSyn ( TyClDecl(..), ConDecl(..), Sig(..), HsPred(..), tyClDeclName, hsTyVarNames, tyClDeclTyVars, - isIfaceSigDecl, isClassDecl, isSynDecl, isClassOpSig + isTypeOrClassDecl, isClassDecl, isSynDecl, isClassOpSig ) import RnHsSyn ( RenamedTyClDecl, tyClDeclFVs ) -import BasicTypes ( RecFlag(..), NewOrData(..), isRec ) -import HscTypes ( implicitTyThingIds ) - -import TcMonad -import TcEnv ( TcEnv, RecTcEnv, TcTyThing(..), TyThing(..), TyThingDetails(..), - tcExtendKindEnv, tcLookup, tcExtendGlobalEnv, tcExtendGlobalValEnv ) -import TcTyDecls ( tcTyDecl1, kcConDetails ) +import RnEnv ( lookupSysName ) +import BasicTypes ( RecFlag(..), NewOrData(..) ) +import HscTypes ( implicitTyThings ) + +import TcRnMonad +import TcEnv ( TcTyThing(..), TyThing(..), TyThingDetails(..), + tcExtendKindEnv, tcLookup, tcLookupGlobal, tcExtendGlobalEnv, + isLocalThing ) +import TcTyDecls ( tcTyDecl, kcConDetails ) import TcClassDcl ( tcClassDecl1 ) import TcInstDcls ( tcAddDeclCtxt ) import TcMonoType ( kcHsTyVars, kcHsType, kcHsLiftedSigType, kcHsContext, mkTyClTyVars ) -import TcMType ( unifyKind, newKindVar, zonkKindEnv ) -import TcType ( Type, Kind, mkArrowKind, liftedTypeKind, zipFunTys ) +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(..), - tyConKind, tyConDataCons, - mkSynTyCon, mkAlgTyCon, mkClassTyCon, mkForeignTyCon, - isRecursiveTyCon ) +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, getSrcLoc, isTyVarName ) +import Name ( Name ) import NameEnv import NameSet import Outputable -import Maybes ( mapMaybe ) -import ErrUtils ( Message ) -import HsDecls ( getClassDeclSysNames ) -import Generics ( mkTyConGenInfo ) +import Maybes ( mapMaybe, orElse, catMaybes ) \end{code} @@ -59,22 +62,22 @@ import Generics ( mkTyConGenInfo ) The main function ~~~~~~~~~~~~~~~~~ \begin{code} -tcTyAndClassDecls :: RecTcEnv -- Knot tying stuff - -> [RenamedTyClDecl] - -> 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 @@ -107,94 +110,102 @@ Step 5: tcTyClDecl1 to tcTyClDecl1. -Step 6: tcTyClDecl1 again - For a recursive group only, check all the decls again, just - but this time with the wimp flag off. Now we can check things - like whether a function argument is an unlifted tuple, looking - through type synonyms properly. We can't do that in Step 5. - -Step 7: Extend environment +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 :: RecTcEnv -> SCC RenamedTyClDecl -> TcM TcEnv -tcGroup unf_env scc - = getDOptsTc `thenTc` \ dflags -> - -- Step 1 - mapNF_Tc getInitialKind decls `thenNF_Tc` \ initial_kinds -> +tcGroup :: EdgeMap -> SCC RenamedTyClDecl + -> TcM TcGblEnv -- Input env extended by types and classes + -- and their implicit Ids,DataCons + +tcGroup edge_map 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 edge_map scc) `thenM` \ is_rec_tycon -> -- Tie the knot - traceTc (text "starting" <+> ppr final_kinds) `thenTc_` - 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 :: [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 = [ ATyCon (classTyCon clas) | AClass clas <- tyclss] - ++ 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 is_rec unf_env) decls `thenTc` \ tycls_details -> + -- Extend the environment with the final + -- TyCons/Classes and check the decls + tcExtendGlobalEnv tyclss $ + mappM tcTyClDecl1 decls `thenM` \ tycls_details -> -- Return results - tcGetEnv `thenNF_Tc` \ env -> - returnTc (tycls_details, all_tyclss, env) - ) `thenTc` \ (_, all_tyclss, env) -> - - tcSetEnv env $ - - traceTc (text "ready for pass 2" <+> ppr (isRec is_rec)) `thenTc_` - - -- Step 6 - -- For a recursive group, check all the types again, - -- this time with the wimp flag off - (if isRec is_rec then - mapTc_ (tcTyClDecl1 NonRecursive unf_env) decls - else - returnTc () - ) `thenTc_` - - traceTc (text "done") `thenTc_` - - -- Step 7 - -- Extend the environment with the final TyCons/Classes - -- and their implicit Ids - tcExtendGlobalValEnv (implicitTyThingIds all_tyclss) tcGetEnv + 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 - is_rec = case scc of - AcyclicSCC _ -> NonRecursive - CyclicSCC _ -> Recursive - decls = case scc of AcyclicSCC decl -> [decl] CyclicSCC decls -> decls -tcTyClDecl1 is_rec unf_env decl - | isClassDecl decl = tcAddDeclCtxt decl (tcClassDecl1 is_rec unf_env decl) - | otherwise = tcAddDeclCtxt decl (tcTyDecl1 is_rec 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 + tcAddDeclCtxt decl $ + case thing of + ATyCon tc -> checkValidTyCon tc + AClass cl -> checkValidClass cl \end{code} @@ -205,11 +216,11 @@ tcTyClDecl1 is_rec unf_env decl %************************************************************************ \begin{code} -getInitialKind :: RenamedTyClDecl -> NF_TcM (Name, TcKind) +getInitialKind :: RenamedTyClDecl -> TcM (Name, TcKind) getInitialKind decl - = kcHsTyVars (tyClDeclTyVars decl) `thenNF_Tc` \ arg_kinds -> - newKindVar `thenNF_Tc` \ result_kind -> - returnNF_Tc (tcdName decl, mk_kind arg_kinds result_kind) + = 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} @@ -239,25 +250,25 @@ kcTyClDecl :: RenamedTyClDecl -> TcM () kcTyClDecl decl@(TySynonym {tcdSynRhs = rhs}) = kcTyClDeclBody decl $ \ result_kind -> - kcHsType rhs `thenTc` \ rhs_kind -> + kcHsType rhs `thenM` \ rhs_kind -> unifyKind result_kind rhs_kind -kcTyClDecl (ForeignType {}) = returnTc () +kcTyClDecl (ForeignType {}) = returnM () kcTyClDecl decl@(TyData {tcdND = new_or_data, tcdCtxt = context, tcdCons = con_decls}) = kcTyClDeclBody decl $ \ result_kind -> - kcHsContext context `thenTc_` - mapTc_ kc_con_decl con_decls + kcHsContext context `thenM_` + mappM_ kc_con_decl (visibleDataCons con_decls) where - kc_con_decl (ConDecl _ _ ex_tvs ex_ctxt details 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 new_or_data ex_ctxt details kcTyClDecl decl@(ClassDecl {tcdCtxt = context, tcdSigs = class_sigs}) = kcTyClDeclBody decl $ \ result_kind -> - kcHsContext context `thenTc_` - mapTc_ kc_sig (filter isClassOpSig class_sigs) + kcHsContext context `thenM_` + mappM_ kc_sig (filter isClassOpSig class_sigs) where kc_sig (ClassOpSig _ _ op_ty loc) = kcHsLiftedSigType op_ty @@ -267,7 +278,7 @@ kcTyClDeclBody :: RenamedTyClDecl -> (Kind -> TcM a) -> TcM a -- check the result kind matches kcTyClDeclBody decl thing_inside = tcAddDeclCtxt decl $ - tcLookup (tcdName decl) `thenNF_Tc` \ thing -> + tcLookup (tcdName decl) `thenM` \ thing -> let kind = case thing of AGlobal (ATyCon tc) -> tyConKind tc @@ -281,6 +292,7 @@ kcTyClDeclBody decl thing_inside \end{code} + %************************************************************************ %* * \subsection{Step 4: Building the tycon/class} @@ -289,13 +301,13 @@ kcTyClDeclBody decl thing_inside \begin{code} buildTyConOrClass - :: DynFlags - -> RecFlag -> NameEnv Kind + :: (Name -> AlgTyConFlavour -> RecFlag) -- Whether it's recursive + -> NameEnv Kind -> FiniteMap TyCon ArgVrcs -> NameEnv TyThingDetails -> RenamedTyClDecl -> TyThing -buildTyConOrClass dflags is_rec kenv rec_vrcs rec_details - (TySynonym {tcdName = tycon_name, tcdTyVars = tyvar_names}) +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 @@ -305,19 +317,16 @@ 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 {tcdND = data_or_new, tcdName = tycon_name, tcdTyVars = tyvar_names, - tcdNCons = nconstrs, tcdSysNames = sys_names}) +buildTyConOrClass rec_tycon kenv rec_vrcs rec_details + (TyData {tcdND = data_or_new, tcdName = tycon_name, + tcdTyVars = tyvar_names}) = ATyCon tycon where tycon = mkAlgTyCon tycon_name tycon_kind tyvars ctxt argvrcs - data_cons nconstrs sel_ids - flavour is_rec gen_info - - gen_info | not (dopt Opt_Generics dflags) = Nothing - | otherwise = mkTyConGenInfo tycon sys_names + data_cons sel_ids flavour + (rec_tycon tycon_name flavour) gen_info - DataTyDetails ctxt data_cons sel_ids = 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 @@ -327,24 +336,25 @@ buildTyConOrClass dflags is_rec kenv rec_vrcs rec_details -- 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 (null . dataConOrigArgTys) data_cons -> EnumTyCon - | otherwise -> DataTyCon + 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 dflags is_rec kenv rec_vrcs rec_details - (ForeignType {tcdName = tycon_name, tcdExtName = tycon_ext_name}) +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 dflags is_rec kenv rec_vrcs rec_details - (ClassDecl {tcdName = class_name, tcdTyVars = tyvar_names, - tcdFDs = fundeps, tcdSysNames = name_list} ) +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 @@ -353,7 +363,7 @@ buildTyConOrClass dflags is_rec kenv rec_vrcs rec_details argvrcs dict_con clas -- Yes! It's a dictionary flavour - is_rec + (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 } @@ -362,7 +372,8 @@ buildTyConOrClass dflags is_rec kenv rec_vrcs rec_details -- [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 = lookupNameEnv_NF rec_details class_name + 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 @@ -387,12 +398,38 @@ bogusVrcs = panic "Bogus tycon arg variances" \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 --- See notes on newypes in types/TypeRep about newtypes. -mkNewTyConRep tc = head (dataConOrigArgTys (head (tyConDataCons tc))) +-- 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} - %************************************************************************ %* * \subsection{Dependency analysis} @@ -402,43 +439,96 @@ mkNewTyConRep tc = head (dataConOrigArgTys (head (tyConDataCons tc))) Dependency analysis ~~~~~~~~~~~~~~~~~~~ \begin{code} -sortByDependency :: [RenamedTyClDecl] -> 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 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 = 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 + 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] + + rec_tycon name (NewTyCon _) + | name `elemNameSet` rec_newtypes = Recursive + | otherwise = NonRecursive + rec_tycon name other_flavour = Recursive in - returnTc decl_sccs - where - tycl_decls = filter (not . isIfaceSigDecl) decls - edges = map mkEdges tycl_decls - - is_syn_decl (d, _, _) = isSynDecl d -\end{code} + returnM rec_tycon -Edges in Type/Class decls -~~~~~~~~~~~~~~~~~~~~~~~~~ +---------------------------------------------------- +-- 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 -\begin{code} -tyClDeclFTVs :: RenamedTyClDecl -> [Name] - -- Find the free non-tyvar vars -tyClDeclFTVs d = foldNameSet add [] (tyClDeclFVs d) - where - add n fvs | isTyVarName n = fvs - | otherwise = n : fvs +---------------------------------------------------- +findCycles edges = [ ds | CyclicSCC ds <- stronglyConnComp edges] + +---------------------------------------------------- +-- 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) ] ---------------------------------------------------- -- mk_cls_edges looks only at the context of class decls @@ -446,12 +536,8 @@ tyClDeclFTVs d = foldNameSet add [] (tyClDeclFVs d) -- superclass hierarchy mkClassEdges :: RenamedTyClDecl -> Maybe (RenamedTyClDecl, Name, [Name]) - mkClassEdges decl@(ClassDecl {tcdCtxt = ctxt, tcdName = name}) = Just (decl, name, [c | HsClassP c _ <- ctxt]) mkClassEdges other_decl = Nothing - -mkEdges :: RenamedTyClDecl -> (RenamedTyClDecl, Name, [Name]) -mkEdges decl = (decl, tyClDeclName decl, tyClDeclFTVs decl) \end{code} @@ -462,21 +548,17 @@ mkEdges decl = (decl, tyClDeclName decl, tyClDeclFTVs decl) %************************************************************************ \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}