qapi: dealloc visitor, implement visit_start_union

{

}

/* If there's no data present, the dealloc visitor has nothing to free.

 * Thus, indicate to visitor code that the subsequent union fields can

 * be skipped. This is not an error condition, since the cleanup of the

 * rest of an object can continue unhindered, so leave errp unset in

 * these cases.

 *

 * NOTE: In cases where we're attempting to deallocate an object that

 * may have missing fields, the field indicating the union type may

 * be missing. In such a case, it's possible we don't have enough

 * information to differentiate data_present == false from a case where

 * data *is* present but happens to be a scalar with a value of 0.

 * This is okay, since in the case of the dealloc visitor there's no

 * work that needs to done in either situation.

 *

 * The current inability in QAPI code to more thoroughly verify a union

 * type in such cases will likely need to be addressed if we wish to

 * implement this interface for other types of visitors in the future,

 * however.

 */

static bool qapi_dealloc_start_union(Visitor *v, bool data_present,

                                     Error **errp)

{

    return data_present;

}

Visitor *qapi_dealloc_get_visitor(QapiDeallocVisitor *v)

{

    return &v->visitor;

    v->visitor.type_str = qapi_dealloc_type_str;

    v->visitor.type_number = qapi_dealloc_type_number;

    v->visitor.type_size = qapi_dealloc_type_size;

    v->visitor.start_union = qapi_dealloc_start_union;

    QTAILQ_INIT(&v->stack);