Function feature_set_sub

common/features.c:245–270

}

bool feature_set_sub(struct feature_set *a,
		     const struct feature_set *b TAKES)
{
	/* Check first, before we change anything! */
	for (size_t i = 0; i < ARRAY_SIZE(b->bits); i++) {
		for (size_t j = 0; j < tal_bytelen(b->bits[i])*8; j++) {
			if (feature_is_set(b->bits[i], j)
			    && !feature_offered(a->bits[i], j)) {
				tal_free_if_taken(b);
				return false;
			}
		}
	}

	for (size_t i = 0; i < ARRAY_SIZE(a->bits); i++) {
		for (size_t j = 0; j < tal_bytelen(b->bits[i])*8; j++) {
			if (feature_is_set(b->bits[i], j))
				clear_feature_bit(a->bits[i], j);
		}
		trim_features(&a->bits[i]);
	}


	tal_free_if_taken(b);
	return true;
}

/* BOLT #1:
 *