From d91bab4247af2686c731c385545e693852c3f51a Mon Sep 17 00:00:00 2001
From: Vitor Santos Costa <vsc@dcc.fc.up.pt>
Date: Mon, 23 Nov 2009 10:01:55 +0000
Subject: [PATCH] make sure goal_expansion is never seen as an undefined goal.
 It should at least always succeed.

---
 pl/boot.yap | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/pl/boot.yap b/pl/boot.yap
index 0ce239ab4..6d5432960 100644
--- a/pl/boot.yap
+++ b/pl/boot.yap
@@ -899,6 +899,8 @@ not(G) :-    \+ '$execute'(G).
 '$check_callable'(_,_).
 
 % Called by the abstract machine, if no clauses exist for a predicate
+'$undefp'([M|expand_goal(G,GEx)]) :- !,
+	G = GEx.
 '$undefp'([M|G]) :-
 	% make sure we do not loop on undefined predicates
         % for undefined_predicates.