Avoid dif/1 attribute with empty list

Closes #1956
2023-09-21 14:00:37 -03:00
parent cac52c0537
commit cb79e83510
2 changed files with 11 additions and 1 deletions
--- a/src/lib/dif.pl
+++ b/src/lib/dif.pl
@@ -35,7 +35,10 @@ vars_remove_goal([], _).
 vars_remove_goal([Var|Vars], Goal0) :-
    get_atts(Var, +dif(Goals0)),
    remove_goal(Goals0, Goal0, Goals),
-    put_atts(Var, +dif(Goals)),
+    (   Goals = [] ->
+        put_atts(Var, -dif(_))
+    ;   put_atts(Var, +dif(Goals))
+    ),
    vars_remove_goal(Vars, Goal0).

 reinforce_goal(Goal0, Goal) :-