X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcTyClsDecls.lhs;h=bdf1488e57c197310d6d54cacf0342c7129646ac;hb=495ef8bd9ef30bffe50ea399b91e3ba09646b59a;hp=7de928a77b6b8722a142d346122604950540f02b;hpb=c4f3290f3d4c2a5c2e81a97717f7fd06ee180f6d;p=ghc-hetmet.git

diff --git a/ghc/compiler/typecheck/TcTyClsDecls.lhs b/ghc/compiler/typecheck/TcTyClsDecls.lhs
index 7de928a..bdf1488 100644
--- a/ghc/compiler/typecheck/TcTyClsDecls.lhs
+++ b/ghc/compiler/typecheck/TcTyClsDecls.lhs
@@ -1,59 +1,64 @@
 %
-% (c) The AQUA Project, Glasgow University, 1996
+% (c) The AQUA Project, Glasgow University, 1996-1998
 %
 \section[TcTyClsDecls]{Typecheck type and class declarations}
 
 \begin{code}
 module TcTyClsDecls (
-	tcTyAndClassDecls1
+	tcTyAndClassDecls
     ) where
 
 #include "HsVersions.h"
 
-import HsSyn		( HsDecl(..), TyDecl(..), ClassDecl(..), 
-			  HsType(..), HsTyVar,
+import HsSyn		( HsDecl(..), TyClDecl(..),
+			  HsType(..), HsTyVarBndr,
 			  ConDecl(..), ConDetails(..), BangType(..),
-			  Sig(..),
-			  hsDeclName
+			  Sig(..), HsPred(..), HsTupCon(..),
+			  tyClDeclName, isClassDecl, isSynDecl
 			)
-import RnHsSyn		( RenamedTyDecl(..), RenamedClassDecl(..), RenamedHsDecl )
-import TcHsSyn		( TcHsBinds )
-import BasicTypes	( RecFlag(..) )
+import RnHsSyn		( RenamedHsDecl, RenamedTyClDecl, listTyCon_name )
+import BasicTypes	( RecFlag(..), NewOrData(..), Arity )
 
 import TcMonad
 import Inst		( InstanceMapper )
-import TcClassDcl	( tcClassDecl1 )
-import TcEnv		( TcIdOcc(..), GlobalValueEnv, tcExtendTyConEnv, tcExtendClassEnv )
-import TcKind		( TcKind, newKindVar, newKindVars, tcDefaultKind, kindToTcKind )
-import TcTyDecls	( tcTyDecl, mkDataBinds )
-import TcMonoType	( tcTyVarScope )
-
-import TyCon		( tyConKind, tyConArity, isSynTyCon )
-import Class		( Class, classBigSig )
-import TyVar		( tyVarKind )
+import TcClassDcl	( kcClassDecl, tcClassDecl1 )
+import TcEnv		( ValueEnv, TcTyThing(..),
+			  tcExtendTypeEnv, getEnvAllTyCons
+			)
+import TcTyDecls	( tcTyDecl, kcTyDecl )
+import TcMonoType	( kcHsTyVar )
+import TcType		( TcKind, newKindVar, newKindVars, kindToTcKind, zonkTcKindToKind )
+
+import Type		( mkArrowKind, boxedTypeKind )
+
+import Class		( Class )
+import Var		( TyVar, tyVarKind )
+import FiniteMap
 import Bag	
+import VarSet
 import Digraph		( stronglyConnComp, SCC(..) )
 import Name		( Name, NamedThing(..), getSrcLoc, isTvOcc, nameOccName )
 import Outputable
-import Maybes		( mapMaybe )
+import Maybes		( mapMaybe, catMaybes, expectJust )
 import UniqSet		( UniqSet, emptyUniqSet,
 			  unitUniqSet, unionUniqSets, 
 			  unionManyUniqSets, uniqSetToList ) 
+import ErrUtils		( Message )
 import SrcLoc		( SrcLoc )
-import TyCon		( TyCon, Arity )
+import TyCon		( TyCon, ArgVrcs )
+import Variance         ( calcTyConArgVrcs )
 import Unique		( Unique, Uniquable(..) )
-import Util		( panic{-, pprTrace-} )
-
+import UniqFM		( listToUFM, lookupUFM )
 \end{code}
 
 The main function
 ~~~~~~~~~~~~~~~~~
 \begin{code}
-tcTyAndClassDecls1 :: GlobalValueEnv -> InstanceMapper	-- Knot tying stuff
-		   -> [RenamedHsDecl]
-		   -> TcM s (TcEnv s)
+tcTyAndClassDecls :: ValueEnv -> InstanceMapper	-- Knot tying stuff
+		  -> [RenamedHsDecl]
+		  -> TcM s TcEnv
 
-tcTyAndClassDecls1 unf_env inst_mapper decls
+tcTyAndClassDecls unf_env inst_mapper decls
   = sortByDependency decls 		`thenTc` \ groups ->
     tcGroups unf_env inst_mapper groups
 
@@ -62,66 +67,44 @@ tcGroups unf_env inst_mapper []
     returnTc env
 
 tcGroups unf_env inst_mapper (group:groups)
-  = tcGroup unf_env inst_mapper group	`thenTc` \ (group_tycons, group_classes) ->
-
-	-- Extend the environment using the new tycons and classes
-    tcExtendTyConEnv [(getName tycon, (kindToTcKind (tyConKind tycon),
-				       if isSynTyCon tycon then Just (tyConArity tycon) else Nothing,
-				       tycon))
-		     | tycon <- group_tycons]	 $
-
-    tcExtendClassEnv [(getName clas, (classKind clas, clas))
-		     | clas <- group_classes]	 $
-
-
-	-- Do the remaining groups
+  = tcGroup unf_env inst_mapper group	`thenTc` \ env ->
+    tcSetEnv env			$
     tcGroups unf_env inst_mapper groups
-  where
-    classKind clas = map (kindToTcKind . tyVarKind) tyvars
-		   where
-		     (tyvars, _, _, _, _) = classBigSig clas
 \end{code}
 
 Dealing with a group
 ~~~~~~~~~~~~~~~~~~~~
 
-Notice the uses of @zipLazy@, which makes sure
-that the knot-tied TyVars, TyCons and Classes aren't looked at too early.
+The knot-tying parameters: @rec_tyclss@ is an alist mapping @Name@s to
+@TcTyThing@s.  @rec_vrcs@ is a finite map from @Name@s to @ArgVrcs@s.
 
-    
 \begin{code}
-tcGroup :: GlobalValueEnv -> InstanceMapper -> SCC RenamedHsDecl -> TcM s ([TyCon], [Class])
+tcGroup :: ValueEnv -> InstanceMapper -> SCC RenamedTyClDecl -> TcM s TcEnv
 tcGroup unf_env inst_mapper scc
-  = 	-- TIE THE KNOT
-    fixTc ( \ ~(rec_tycons, rec_classes) ->
-
-		-- EXTEND TYPE AND CLASS ENVIRONMENTS
-      let
-        mk_tycon_bind (name, arity) = newKindVar	`thenNF_Tc` \ kind ->
-				      returnNF_Tc (name, (kind, arity, find name rec_tycons))
-
-	mk_class_bind (name, arity) = newKindVars arity	 `thenNF_Tc` \ kinds ->
-				      returnNF_Tc (name, (kinds, find name rec_classes))
-
-        find name []		 = pprPanic "tcGroup" (ppr name)
-	find name (thing:things) | name == getName thing = thing
-				 | otherwise		 = find name things
-
-      in
-      mapNF_Tc mk_tycon_bind tycon_names_w_arities    `thenNF_Tc` \ tycon_binds ->
-      mapNF_Tc mk_class_bind class_names_w_arities    `thenNF_Tc` \ class_binds ->
-      tcExtendTyConEnv tycon_binds	  $
-      tcExtendClassEnv class_binds	  $
-
-		-- DEAL WITH TYPE VARIABLES
-      tcTyVarScope tyvar_names 			( \ tyvars ->
-
-		-- DEAL WITH THE DEFINITIONS THEMSELVES
-	foldlTc (tcDecl is_rec_group unf_env inst_mapper) ([], []) decls
-      )						`thenTc` \ (tycons, classes) ->
-
-      returnTc (tycons, classes)
-    )
+  = 	-- Do kind checking
+    mapNF_Tc getTyBinding1 decls 			`thenNF_Tc` \ ty_env_stuff1 ->
+    tcExtendTypeEnv ty_env_stuff1 (mapTc kcDecl decls)	`thenTc_`
+
+	-- Tie the knot
+--  traceTc (ppr (map fst ty_env_stuff1))		`thenTc_`
+    fixTc ( \ ~(rec_tyclss,  _) ->
+	let
+	    rec_env    = listToUFM rec_tyclss
+	    rec_tycons = getEnvAllTyCons rec_tyclss
+            rec_vrcs   = calcTyConArgVrcs rec_tycons
+	in
+	
+		-- Do type checking
+	mapNF_Tc (getTyBinding2 rec_env) ty_env_stuff1	`thenNF_Tc` \ ty_env_stuff2 ->
+	tcExtendTypeEnv ty_env_stuff2				$
+	mapTc (tcDecl is_rec_group unf_env inst_mapper rec_vrcs) decls
+                                                                `thenTc` \ tyclss ->
+
+	tcGetEnv						`thenTc` \ env -> 
+	returnTc (tyclss, env)
+    )								`thenTc` \ (_, env) ->
+--  traceTc (text "done" <+> ppr (map fst ty_env_stuff1))	`thenTc_`
+    returnTc env
   where
     is_rec_group = case scc of
 			AcyclicSCC _ -> NonRecursive
@@ -130,188 +113,232 @@ tcGroup unf_env inst_mapper scc
     decls = case scc of
 		AcyclicSCC decl -> [decl]
 		CyclicSCC decls -> decls
-
-    (tyvar_names, tycon_names_w_arities, class_names_w_arities) = get_binders decls
 \end{code}
 
 Dealing with one decl
 ~~~~~~~~~~~~~~~~~~~~~
 \begin{code}
+kcDecl decl
+  = tcAddDeclCtxt decl		$
+    if isClassDecl decl then
+	kcClassDecl decl
+    else
+	kcTyDecl    decl
+
 tcDecl  :: RecFlag 			-- True => recursive group
-	-> GlobalValueEnv -> InstanceMapper
-	-> ([TyCon], [Class])		-- Accumulating parameter
-	-> RenamedHsDecl
-	-> TcM s ([TyCon], [Class])
-
-tcDecl is_rec_group unf_env inst_mapper (tycons, classes) (TyD decl)
-  = tcTyDecl is_rec_group decl	`thenTc` \ tycon ->
-    returnTc (tycon:tycons, classes)
-
-tcDecl is_rec_group unf_env inst_mapper (tycons, classes) (ClD decl)
-  = tcClassDecl1 unf_env inst_mapper decl   `thenTc` \ clas ->
-    returnTc (tycons, clas:classes)
+	 -> ValueEnv -> InstanceMapper -> FiniteMap Name ArgVrcs
+	 -> RenamedTyClDecl -> TcM s (Name, TcTyThing)
+
+tcDecl is_rec_group unf_env inst_mapper vrcs_env decl
+  = tcAddDeclCtxt decl		$
+    if isClassDecl decl then
+	tcClassDecl1 unf_env inst_mapper vrcs_env decl
+    else
+	tcTyDecl is_rec_group vrcs_env decl
+		
+
+tcAddDeclCtxt decl thing_inside
+  = tcAddSrcLoc loc 	$
+    tcAddErrCtxt ctxt 	$
+    thing_inside
+  where
+     (name, loc, thing)
+	= case decl of
+	    (ClassDecl _ name _ _ _ _ _ _ _ _ _ loc) -> (name, loc, "class")
+	    (TySynonym name _ _ loc)	             -> (name, loc, "type synonym")
+	    (TyData NewType  _ name _ _ _ _ _ loc)   -> (name, loc, "data type")
+	    (TyData DataType _ name _ _ _ _ _ loc)   -> (name, loc, "newtype")
+
+     ctxt = hsep [ptext SLIT("In the"), text thing, 
+		  ptext SLIT("declaration for"), quotes (ppr name)]
+\end{code}
+
+
+getTyBinders
+~~~~~~~~~~~
+Extract *binding* names from type and class decls.  Type variables are
+bound in type, data, newtype and class declarations, 
+	*and* the polytypes in the class op sigs.
+	*and* the existentially quantified contexts in datacon decls
+
+Why do we need to grab all these type variables at once, including
+those locally-quantified type variables in class op signatures?
+
+   [Incidentally, this only works because the names are all unique by now.]
+
+Because we can only commit to the final kind of a type variable when
+we've completed the mutually recursive group. For example:
+
+class C a where
+   op :: D b => a -> b -> b
+
+class D c where
+   bop :: (Monad c) => ...
+
+Here, the kind of the locally-polymorphic type variable "b"
+depends on *all the uses of class D*.  For example, the use of
+Monad c in bop's type signature means that D must have kind Type->Type.
+
+    [April 00: looks as if we've dropped this subtlety; I'm not sure when]
+
+\begin{code}
+getTyBinding1 :: RenamedTyClDecl -> NF_TcM s (Name, (TcKind, TcTyThing))
+getTyBinding1 (TySynonym name tyvars _ _)
+ = mapNF_Tc kcHsTyVar tyvars		`thenNF_Tc` \ arg_kinds ->
+   newKindVar				`thenNF_Tc` \ result_kind  ->
+   returnNF_Tc (name, (foldr mkArrowKind result_kind arg_kinds, 
+		       ASynTyCon (pprPanic "ATyCon: syn" (ppr name)) (length tyvars)))
+
+getTyBinding1 (TyData _ _ name tyvars _ _ _ _ _)
+ = mapNF_Tc kcHsTyVar tyvars		`thenNF_Tc` \ arg_kinds ->
+   returnNF_Tc (name, (foldr mkArrowKind boxedTypeKind arg_kinds, 
+		       ADataTyCon (error "ATyCon: data")))
+
+getTyBinding1 (ClassDecl _ name tyvars _ _ _ _ _ _ _ _ _)
+ = mapNF_Tc kcHsTyVar tyvars		`thenNF_Tc` \ arg_kinds ->
+   returnNF_Tc (name, (foldr mkArrowKind boxedTypeKind arg_kinds, 
+		       AClass (pprPanic "AClass" (ppr name)) (length tyvars)))
+
+-- Zonk the kind to its final form, and lookup the 
+-- recursive tycon/class
+getTyBinding2 rec_env (name, (tc_kind, thing))
+  = zonkTcKindToKind tc_kind		`thenNF_Tc` \ kind ->
+    returnNF_Tc (name, (kind, mk_thing thing (lookupUFM rec_env name)))
+  where
+    mk_thing (ADataTyCon _)      ~(Just (ADataTyCon tc))  = ADataTyCon tc
+    mk_thing (ASynTyCon _ arity) ~(Just (ASynTyCon tc _)) = ASynTyCon tc arity
+    mk_thing (AClass _ arity)    ~(Just (AClass cls _))   = AClass cls arity
 \end{code}
 
+
+%************************************************************************
+%*									*
+\subsection{Dependency analysis}
+%*									*
+%************************************************************************
+
 Dependency analysis
 ~~~~~~~~~~~~~~~~~~~
 \begin{code}
-sortByDependency :: [RenamedHsDecl] -> TcM s [SCC RenamedHsDecl]
+sortByDependency :: [RenamedHsDecl] -> TcM s [SCC RenamedTyClDecl]
 sortByDependency decls
-  = let		-- CHECK FOR SYNONYM CYCLES
+  = let		-- CHECK FOR CLASS CYCLES
+	cls_sccs   = stronglyConnComp (mapMaybe mk_cls_edges tycl_decls)
+	cls_cycles = [ decls | CyclicSCC decls <- cls_sccs]
+    in
+    checkTc (null cls_cycles) (classCycleErr cls_cycles)	`thenTc_`
+
+    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_`
 
-    let		-- CHECK FOR CLASS CYCLES
-	cls_sccs   = stronglyConnComp (filter is_cls_decl edges)
-	cls_cycles = [ decls | CyclicSCC decls <- cls_sccs]
-
-    in
-    checkTc (null cls_cycles) (classCycleErr cls_cycles)	`thenTc_`
-
-		-- DO THE MAIN DEPENDENCY ANALYSIS
+    	-- DO THE MAIN DEPENDENCY ANALYSIS
     let
-	decl_sccs  = stronglyConnComp (filter is_ty_cls_decl edges)
+	decl_sccs  = stronglyConnComp edges
     in
     returnTc decl_sccs
-
   where
-    edges = mapMaybe mk_edges decls
+    tycl_decls = [d | TyClD d <- decls]
+    edges      = map mk_edges tycl_decls
     
-bag_acyclic (AcyclicSCC scc) = unitBag scc
-bag_acyclic (CyclicSCC sccs) = listToBag sccs
-
-is_syn_decl (TyD (TySynonym _ _ _ _), _, _) = True
-is_syn_decl _		                    = False
-
-is_ty_cls_decl (TyD _, _, _) = True
-is_ty_cls_decl (ClD _, _, _) = True
-is_ty_cls_decl other         = False
-
-is_cls_decl (ClD _, _, _) = True
-is_cls_decl other         = False
+    is_syn_decl (d, _, _) = isSynDecl d
 \end{code}
 
 Edges in Type/Class decls
 ~~~~~~~~~~~~~~~~~~~~~~~~~
+
 \begin{code}
-mk_edges decl@(TyD (TyData _ ctxt name _ condecls derivs _ _))
-  = Just (decl, uniqueOf name, uniqSetToList (get_ctxt ctxt `unionUniqSets` 
-					 get_cons condecls `unionUniqSets` 
+----------------------------------------------------
+-- 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@(TyD (TySynonym name _ rhs _))
-  = Just (decl, uniqueOf name, uniqSetToList (get_ty rhs))
+mk_edges decl@(TySynonym name _ rhs _)
+  = (decl, getUnique name, uniqSetToList (get_ty rhs))
 
-mk_edges decl@(ClD (ClassDecl ctxt name _ sigs _ _ _ _ _))
-  = Just (decl, uniqueOf name, uniqSetToList (get_ctxt ctxt `unionUniqSets`
+mk_edges decl@(ClassDecl ctxt name _ _ sigs _ _ _ _ _ _ _)
+  = (decl, getUnique name, uniqSetToList (get_ctxt ctxt `unionUniqSets`
 				         get_sigs sigs))
 
-mk_edges other_decl = Nothing
 
-get_ctxt ctxt = unionManyUniqSets (map (set_name.fst) ctxt)
+----------------------------------------------------
+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_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 (NewCon ty)          =  get_ty ty
+get_con_details (NewCon ty _)        = get_ty ty
 get_con_details (RecCon nbtys)       = unionManyUniqSets (map (get_bty.snd) nbtys)
 
+----------------------------------------------------
 get_bty (Banged ty)   = get_ty ty
 get_bty (Unbanged ty) = get_ty ty
-
-get_ty (MonoTyVar name)
-  = if isTvOcc (nameOccName name) then emptyUniqSet else set_name name
-get_ty (MonoTyApp ty1 ty2)
-  = unionUniqSets (get_ty ty1) (get_ty ty2)
-get_ty (MonoFunTy ty1 ty2)	
-  = unionUniqSets (get_ty ty1) (get_ty ty2)
-get_ty (MonoListTy tc ty)
-  = set_name tc `unionUniqSets` get_ty ty
-get_ty (MonoTupleTy tc tys)
-  = set_name tc `unionUniqSets` get_tys tys
-get_ty (HsForAllTy _ ctxt mty)
-  = get_ctxt ctxt `unionUniqSets` get_ty mty
-get_ty other = panic "TcTyClsDecls:get_ty"
-
-get_tys tys
-  = unionManyUniqSets (map get_ty tys)
-
+get_bty (Unpacked ty) = get_ty ty
+
+----------------------------------------------------
+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
+
+----------------------------------------------------
+get_tys tys = unionManyUniqSets (map get_ty tys)
+
+----------------------------------------------------
 get_sigs sigs
   = unionManyUniqSets (map get_sig sigs)
   where 
-    get_sig (ClassOpSig _ _ ty _) = get_ty ty
+    get_sig (ClassOpSig _ _ _ ty _) = get_ty ty
+    get_sig (FixSig _)		    = emptyUniqSet
     get_sig other = panic "TcTyClsDecls:get_sig"
 
-set_name name = unitUniqSet (uniqueOf name)
-
+----------------------------------------------------
+set_name name = unitUniqSet (getUnique name)
 set_to_bag set = listToBag (uniqSetToList set)
 \end{code}
 
 
-get_binders
-~~~~~~~~~~~
-Extract *binding* names from type and class decls.  Type variables are
-bound in type, data, newtype and class declarations and the polytypes
-in the class op sigs.
-
-Why do we need to grab all these type variables at once, including
-those locally-quantified type variables in class op signatures?
-Because we can only commit to the final kind of a type variable when
-we've completed the mutually recursive group. For example:
-
-class C a where
-   op :: D b => a -> b -> b
-
-class D c where
-   bop :: (Monad c) => ...
-
-Here, the kind of the locally-polymorphic type variable "b"
-depends on *all the uses of class D*.  For example, the use of
-Monad c in bop's type signature means that D must have kind Type->Type.
-
-
 \begin{code}
-get_binders :: [RenamedHsDecl]
-	    -> ([HsTyVar Name],		-- TyVars;  no dups
-		[(Name, Maybe Arity)],	-- Tycons;  no dups; arities for synonyms
-		[(Name, Arity)])	-- Classes; no dups; with their arities
+typeCycleErr, classCycleErr :: [[RenamedTyClDecl]] -> Message
 
-get_binders decls = (bagToList tyvars, bagToList tycons, bagToList classes)
-  where
-    (tyvars, tycons, classes) = foldr (union3 . get_binders1)
-				      (emptyBag,emptyBag,emptyBag)
-				      decls
-
-    union3 (a1,a2,a3) (b1,b2,b3)
-      = (a1 `unionBags` b1, a2 `unionBags` b2, a3 `unionBags` b3)
-
-get_binders1 (TyD (TyData _ _ name tyvars _ _ _ _))
- = (listToBag tyvars, unitBag (name,Nothing), emptyBag)
-get_binders1 (TyD (TySynonym name tyvars _ _))
- = (listToBag tyvars, unitBag (name, Just (length tyvars)), emptyBag)
-get_binders1 (ClD (ClassDecl _ name tyvars sigs _ _ _ _ _))
- = (listToBag tyvars `unionBags` sigs_tvs sigs,
-    emptyBag, unitBag (name, length tyvars))
-
-sigs_tvs sigs = unionManyBags (map sig_tvs sigs)
-  where 
-    sig_tvs (ClassOpSig _ _ ty _) = pty_tvs ty
-    pty_tvs (HsForAllTy tvs _ _)  = listToBag tvs 	-- tvs doesn't include the class tyvar
-    pty_tvs other		  = emptyBag
-\end{code}
-
-
-\begin{code}
 typeCycleErr syn_cycles
   = vcat (map (pp_cycle "Cycle in type declarations:") syn_cycles)
 
@@ -325,5 +352,5 @@ pp_cycle str decls
     pp_decl decl
       = hsep [quotes (ppr name), ptext SLIT("at"), ppr (getSrcLoc name)]
      where
-        name = hsDeclName decl
+        name = tyClDeclName decl
 \end{code}