From d3632dd48ce5866cbdd91ffc63fe5a32b5cd2ce1 Mon Sep 17 00:00:00 2001
From: Vitor Santos Costa <vsc@dcc.fc.up.pt>
Date: Thu, 7 May 2009 23:51:18 -0400
Subject: [PATCH] fix case where you may bind variable (eg, freeze(X,Y)), obs
 from Ulrich Neumerkel.

---
 pl/corout.yap | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pl/corout.yap b/pl/corout.yap
index 0488b4bae..c4242f535 100644
--- a/pl/corout.yap
+++ b/pl/corout.yap
@@ -524,7 +524,8 @@ frozen(V, LG) :-
 	'$purge_done_goals'(G0, GF).
 '$purge_done_goals'(['$redo_freeze'(_Done, _, CallCleanup)|G0], GF) :-
 	nonvar(CallCleanup),
-	CallCleanup = _:'$clean_call'(_), !,
+	% be careful about possibly adding extra binding at this point.
+	CallCleanup = _:T, nonvar(T), T = '$clean_call'(_), !,
 	'$purge_done_goals'(G0, GF).
 '$purge_done_goals'(['$redo_eq'(Done, _, _, _)|G0], GF) :- nonvar(Done), !,
 	'$purge_done_goals'(G0, GF).