- const struct binomial_test *bst = (const struct binomial_test *) test;
- const struct one_sample_test *ost = (const struct one_sample_test*) test;
+ const struct one_sample_test *ost = UP_CAST (test, const struct one_sample_test, parent);
+ const struct binomial_test *bst = UP_CAST (ost, const struct binomial_test, parent);