X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcExpr.lhs;h=39e8a5c959a0689a9db7fa1214ca92e9aa85a9ca;hb=f750bec77c4f1b6d986dfa237df63a70689e9849;hp=14a1d6d390aac606e6e5122917804958212847a2;hpb=ff8e1d01524b48e028b09e2b04b2e5303cb6d95f;p=ghc-hetmet.git

diff --git a/compiler/typecheck/TcExpr.lhs b/compiler/typecheck/TcExpr.lhs
index 14a1d6d..39e8a5c 100644
--- a/compiler/typecheck/TcExpr.lhs
+++ b/compiler/typecheck/TcExpr.lhs
@@ -29,6 +29,7 @@ import TcHsType
 import TcPat
 import TcMType
 import TcType
+import TcIface	( checkWiredInTyCon )
 import Id
 import DataCon
 import Name
@@ -302,10 +303,11 @@ tcExpr (ExplicitTuple exprs boxity) res_ty
   = do	{ tvs <- newBoxyTyVars [argTypeKind | e <- exprs]
 	; let tup_tc     = tupleTyCon boxity (length exprs)
 	      tup_res_ty = mkTyConApp tup_tc (mkTyVarTys tvs)
-	; arg_tys   <- preSubType tvs (mkVarSet tvs) tup_res_ty res_ty
-	; exprs'    <-  tcPolyExprs exprs arg_tys
+	; checkWiredInTyCon tup_tc	-- Ensure instances are available
+	; arg_tys  <- preSubType tvs (mkVarSet tvs) tup_res_ty res_ty
+	; exprs'   <- tcPolyExprs exprs arg_tys
 	; arg_tys' <- mapM refineBox arg_tys
-	; co_fn <- tcFunResTy (tyConName tup_tc) (mkTyConApp tup_tc arg_tys') res_ty
+	; co_fn    <- tcFunResTy (tyConName tup_tc) (mkTyConApp tup_tc arg_tys') res_ty
 	; return (mkHsWrap co_fn (ExplicitTuple exprs' boxity)) }
 
 tcExpr (HsProc pat cmd) res_ty
@@ -484,7 +486,6 @@ tcExpr expr@(RecordUpd record_expr hrbinds@(HsRecordBinds rbinds) _ _ _) res_ty
 		 = WpCo $ mkTyConApp co_con scrut_inst_tys
 		 | otherwise
 		 = idHsWrapper
-	scrut_ty = mkTyConApp tycon scrut_inst_tys	-- Type of pattern, the result of the cast
     in
 	-- Phew!
     returnM (mkHsWrap co_fn (RecordUpd (mkLHsWrap scrut_co record_expr') rbinds'