isl_qpolynomial_opt_on_domain: handle empty input

diff --git a/isl_polynomial.c b/isl_polynomial.c
index 28b9f7e..7269224 100644 (file)
--- a/isl_polynomial.c
+++ b/isl_polynomial.c
@@ -2987,6 +2987,9 @@ __isl_give isl_qpolynomial *isl_qpolynomial_opt_on_domain(
        if (isl_set_foreach_point(set, opt_fn, &data) < 0)
                goto error;
 
+       if (data.first)
+               data.opt = isl_qpolynomial_zero(isl_qpolynomial_get_dim(qp));
+
        isl_set_free(set);
        isl_qpolynomial_free(qp);
        return data.opt;