X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Fiface%2FBuildTyCl.lhs;h=d1118c01286375ae1cca62c81235d0ee599cd1c8;hb=0b86bc9b022a5965d2b35f143ff4b919f784e676;hp=5c76d55ab61ef7d864f682b518a771358d2be02a;hpb=2cab0d72186713bc2be393b3ee2c39b46a453783;p=ghc-hetmet.git

diff --git a/compiler/iface/BuildTyCl.lhs b/compiler/iface/BuildTyCl.lhs
index 5c76d55..d1118c0 100644
--- a/compiler/iface/BuildTyCl.lhs
+++ b/compiler/iface/BuildTyCl.lhs
@@ -29,7 +29,7 @@ import Class		( mkClass, Class( classTyCon), FunDep, DefMeth(..) )
 import TyCon		( mkSynTyCon, mkAlgTyCon, visibleDataCons, tyConStupidTheta,
 			  tyConDataCons, isNewTyCon, mkClassTyCon, TyCon( tyConTyVars ),
 			  isRecursiveTyCon, tyConArity,
-			  ArgVrcs, AlgTyConRhs(..), newTyConRhs )
+			  AlgTyConRhs(..), newTyConRhs )
 import Type		( mkArrowKinds, liftedTypeKind, typeKind, 
 			  tyVarsOfType, tyVarsOfTypes, tyVarsOfPred,
 			  splitTyConApp_maybe, splitAppTy_maybe, getTyVar_maybe,
@@ -45,8 +45,8 @@ import List		( nub )
 
 \begin{code}
 ------------------------------------------------------
-buildSynTyCon name tvs rhs_ty arg_vrcs
-  = mkSynTyCon name kind tvs rhs_ty arg_vrcs
+buildSynTyCon name tvs rhs_ty
+  = mkSynTyCon name kind tvs rhs_ty
   where
     kind = mkArrowKinds (map tyVarKind tvs) (typeKind rhs_ty)
 
@@ -55,13 +55,13 @@ buildSynTyCon name tvs rhs_ty arg_vrcs
 buildAlgTyCon :: Name -> [TyVar] 
 	      -> ThetaType		-- Stupid theta
 	      -> AlgTyConRhs
-	      -> ArgVrcs -> RecFlag
+	      -> RecFlag
 	      -> Bool			-- True <=> want generics functions
 	      -> Bool			-- True <=> was declared in GADT syntax
 	      -> TcRnIf m n TyCon
 
-buildAlgTyCon tc_name tvs stupid_theta rhs arg_vrcs is_rec want_generics gadt_syn
-  = do	{ let { tycon = mkAlgTyCon tc_name kind tvs arg_vrcs stupid_theta
+buildAlgTyCon tc_name tvs stupid_theta rhs is_rec want_generics gadt_syn
+  = do	{ let { tycon = mkAlgTyCon tc_name kind tvs stupid_theta
 				   rhs fields is_rec want_generics gadt_syn
 	      ; kind    = mkArrowKinds (map tyVarKind tvs) liftedTypeKind
 	      ; fields  = mkTyConSelIds tycon rhs
@@ -82,13 +82,24 @@ mkNewTyConRhs :: Name -> TyCon -> DataCon -> TcRnIf m n AlgTyConRhs
 -- because the latter is part of a knot, whereas the former is not.
 mkNewTyConRhs tycon_name tycon con 
   = do	{ co_tycon_name <- newImplicitBinder tycon_name mkNewTyCoOcc
-	; let co_tycon = mkNewTypeCoercion co_tycon_name tycon tvs rhs_ty 
+	; let co_tycon = mkNewTypeCoercion co_tycon_name tycon tvs rhs_ty
+              cocon_maybe 
+                | all_coercions || isRecursiveTyCon tycon 
+                = Just co_tycon
+                | otherwise              
+                = Nothing
 	; return (NewTyCon { data_con = con, 
- 		       	     nt_co = co_tycon,
+ 		       	     nt_co = cocon_maybe, 
+                             -- Coreview looks through newtypes with a Nothing
+                             -- for nt_co, or uses explicit coercions otherwise
 		       	     nt_rhs = rhs_ty,
 		       	     nt_etad_rhs = eta_reduce tvs rhs_ty,
 		       	     nt_rep = mkNewTyConRep tycon rhs_ty }) }
   where
+        -- if all_coercions is True then we use coercions for all newtypes
+        -- otherwise we use coercions for recursive newtypes and look through
+        -- non-recursive newtypes
+    all_coercions = True
     tvs    = tyConTyVars tycon
     rhs_ty = head (dataConInstOrigArgTys con (mkTyVarTys tvs))
 	-- Instantiate the data con with the 
@@ -116,9 +127,8 @@ mkNewTyConRep :: TyCon		-- The original type constructor
 -- 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).
+-- splitTyConApp_maybe no longer looks through newtypes, so we must
+-- deal explicitly with this case
 -- 
 -- The trick is to to deal correctly with recursive newtypes
 -- such as	newtype T = MkT T
@@ -133,10 +143,11 @@ mkNewTyConRep tc rhs_ty
 	= case splitTyConApp_maybe rep_ty of
 	    Just (tc, tys)
 		| tc `elem` tcs -> unitTy	-- Recursive loop
-		| isNewTyCon tc -> ASSERT( isRecursiveTyCon tc )
-					-- Non-recursive ones have been 
-					-- dealt with by splitTyConApp_maybe
-				   go (tc:tcs) (substTyWith tvs tys rhs_ty)
+		| isNewTyCon tc -> 
+                    if isRecursiveTyCon tc then
+			go (tc:tcs) (substTyWith tvs tys rhs_ty)
+                    else
+                        substTyWith tvs tys rhs_ty
 		where
 		  (tvs, rhs_ty) = newTyConRhs tc
 
@@ -207,10 +218,10 @@ mkTyConSelIds tycon rhs
 buildClass :: Name -> [TyVar] -> ThetaType
 	   -> [FunDep TyVar]		-- Functional dependencies
 	   -> [(Name, DefMeth, Type)]	-- Method info
-	   -> RecFlag -> ArgVrcs	-- Info for type constructor
+	   -> RecFlag			-- Info for type constructor
 	   -> TcRnIf m n Class
 
-buildClass class_name tvs sc_theta fds sig_stuff tc_isrec tc_vrcs
+buildClass class_name tvs sc_theta fds sig_stuff tc_isrec
   = do	{ tycon_name <- newImplicitBinder class_name mkClassTyConOcc
 	; datacon_name <- newImplicitBinder class_name mkClassDataConOcc
 		-- The class name is the 'parent' for this datacon, not its tycon,
@@ -253,7 +264,7 @@ buildClass class_name tvs sc_theta fds sig_stuff tc_isrec tc_vrcs
 	; let {	clas_kind = mkArrowKinds (map tyVarKind tvs) liftedTypeKind
 
  	      ; tycon = mkClassTyCon tycon_name clas_kind tvs
-                             tc_vrcs rhs rec_clas tc_isrec
+                             rhs rec_clas tc_isrec
 		-- 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 }