From a9fa343bad934ba416981f2c6b7d909b84ed1aa2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?V=C3=ADtor=20Santos=20Costa?= <vsc@dcc.fc.up.pt>
Date: Thu, 22 Oct 2015 11:58:29 +0100
Subject: [PATCH] don't expand meta-vars and don't expand expanded variables...

---
 pl/modules.yap | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/pl/modules.yap b/pl/modules.yap
index 6be66e2eb..8cd4c8b77 100644
--- a/pl/modules.yap
+++ b/pl/modules.yap
@@ -765,7 +765,11 @@ expand_goal(G, NG) :-
 	'$do_expand'(G, Mod, prolog, []-G,  NG), !.
 expand_goal(G, G).
 
-'$do_expand'(G, _HM, _BM, _SM, _, G) :- var(G), !.
+'$do_expand'(G, _HM, _BM, SM, HVars-_, OG) :- var(G), !,
+	( lists:identical_member(G, HVars) -> OG = G; OG = SM:G).
+% nothing I can do here:
+'$do_expand'(M:G, _HM, _BM, _SM,  _HVars, M:G) :- !,
+	 nonvar(M), var(G), !.
 '$do_expand'(M:G, HM, _BM, _SM,  HVars, M:GI) :- !,
 	 nonvar(M),
 	'$do_expand'(G, HM, M, M, HVars, GI).