rdbuf is not destroyed.
This destructor is
virtual because the base class destructor, ios_base::~ios_base is virtual.
 Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
|DR||Applied to||Behavior as published||Correct behavior|
|LWG 53||C++98|| it was unspecified whether
||it is not destroyed|