void visit_start_struct(Visitor *v, const char *name, void **obj, size_t size, Error **errp) { Error *err = NULL; if (obj) { assert(size); assert(v->type != VISITOR_OUTPUT || *obj); } v->start_struct(v, name, obj, size, &err); if (obj && v->type == VISITOR_INPUT) { assert(!err != !*obj); } error_propagate(errp, err); }