From b96ff781bc806ff37b4abe9e3b7d986728473b2a Mon Sep 17 00:00:00 2001
From: Markus Triska <triska@metalevel.at>
Date: Wed, 3 Feb 2021 23:49:28 +0100
Subject: [PATCH] add meta_predicate declaration for must_succeed/1

---
 src/lib/clpz.pl | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/lib/clpz.pl b/src/lib/clpz.pl
index e72a33c1..b7fa0ea7 100644
--- a/src/lib/clpz.pl
+++ b/src/lib/clpz.pl
@@ -5884,10 +5884,12 @@ difference_arcs([V|Vs], FL0) -->
 
 writeln(T) :- write(T), nl.
 
+:- meta_predicate must_succeed(0).
+
 must_succeed(G) :-
-    (G -> true
-     ;write(failed-G), halt
-    ).
+        (   G -> true
+        ;   throw(failed-G)
+        ).
 
 enumerate([], _) --> [].
 enumerate([N|Ns], V) -->
-- 
2.54.0