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/tests/dif.pl
+++ b/src/tests/dif.pl
@@ -189,6 +189,13 @@ test("dif#12 but with multiple variables in the residuals",(
    Res = []
 )).

+% https://github.com/mthom/scryer-prolog/issues/1956
+test("scryer-prolog#1956",(
+    call_residue_vars((dif(a-a,X-_),X=b), Res),
+    X == b,
+    Res = []
+)).
+
 main :-
    findall(test(Name, Goal), test(Name, Goal), Tests),
    run_tests(Tests, Failed),