From 0ddda0a864109f69273dc2d056986f9d240a83de Mon Sep 17 00:00:00 2001
From: Markus Triska <triska@metalevel.at>
Date: Thu, 3 Aug 2023 00:26:40 +0200
Subject: [PATCH] FIXED: do not attach constraint if the propagator is already
 entailed and killed

Example:

    ?- A#=A//A#==>B,A-B=1-1.
       A = 1, B = 1.

This addresses #1941.
---
 src/lib/clpz.pl | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/lib/clpz.pl b/src/lib/clpz.pl
index 38e52657..ed01f079 100644
--- a/src/lib/clpz.pl
+++ b/src/lib/clpz.pl
@@ -3784,8 +3784,11 @@ var_eq(V, N, #V #= N).
 % Match variables to created skeleton.
 
 skeleton(Vs, Vs-Prop) :-
-        maplist(prop_init(Prop), Vs),
-        trigger_once(Prop).
+        (   propagator_state(Prop, State), State == dead ->
+            true
+        ;   maplist(prop_init(Prop), Vs),
+            trigger_once(Prop)
+        ).
 
 /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    A drep is a user-accessible and visible domain representation. N,
-- 
2.54.0