#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 BasicTypes ( RecFlag(..), NewOrData(..) )
-
-import TcMonad
-import TcEnv ( ValueEnv, TyThing(..), TyThingDetails(..), tyThingKind,
- tcExtendTypeEnv, tcExtendKindEnv, tcLookupTy
- )
-import TcTyDecls ( tcTyDecl1, kcConDetails, mkNewTyConRep )
+import RnHsSyn ( RenamedTyClDecl, tyClDeclFVs )
+import BasicTypes ( RecFlag(..), isNonRec, NewOrData(..) )
+import HscTypes ( implicitTyThingIds )
+
+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 FiniteMap
import Digraph ( stronglyConnComp, SCC(..) )
-import Name ( Name, NamedThing(..), NameEnv, getSrcLoc, isTvOcc, nameOccName,
- mkNameEnv, lookupNameEnv_NF
- )
+import Name ( Name, getSrcLoc )
+import NameEnv
+import NameSet
import Outputable
-import Maybes ( mapMaybe, catMaybes )
-import UniqSet ( emptyUniqSet, unitUniqSet, unionUniqSets,
- unionManyUniqSets, uniqSetToList )
+import Maybes ( mapMaybe )
import ErrUtils ( Message )
-import Unique ( Unique, Uniquable(..) )
-import HsDecls ( fromClassDeclNameList )
-import Generics ( mkTyConGenInfo )
\end{code}
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 [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
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 :: SCC RenamedTyClDecl
+ -> TcM (TcGblEnv, -- Input env extended by types and classes only
+ [TyThing]) -- Things defined by this group
+
+tcGroup 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
+ checkLoops is_rec decls `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 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
+ -- 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
is_rec = case scc of
AcyclicSCC _ -> NonRecursive
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}
%************************************************************************
\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}
\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}
\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
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
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
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}
%************************************************************************
%* *
Dependency analysis
~~~~~~~~~~~~~~~~~~~
\begin{code}
-sortByDependency :: [RenamedHsDecl] -> TcM [SCC RenamedTyClDecl]
-sortByDependency decls
+checkLoops :: RecFlag -> [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 is_rec decls
+ | isNonRec is_rec
+ = returnM (\ _ _ -> NonRecursive)
+
+ | otherwise -- Recursive group
= 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]
-
- in
- checkTc (null syn_cycles) (typeCycleErr syn_cycles) `thenTc_`
-
- -- DO THE MAIN DEPENDENCY ANALYSIS
- let
- decl_sccs = stronglyConnComp edges
+ syn_edges = map mkEdges (filter isSynDecl decls)
+ syn_cycles = findCycles syn_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))
+ mapM_ (cycleErr "type synonym") syn_cycles `thenM_`
+ 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]
-----------------------------------------------------
-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)
-
-----------------------------------------------------
-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)
+mkEdges :: RenamedTyClDecl -> (RenamedTyClDecl, Name, [Name])
+mkEdges decl = (decl, tyClDeclName decl, 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}
%************************************************************************
\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}