Also mark CWG78 as superseded by CWG2536.
CWG253 is concerned with users required to explicitly declare defaulted default constructor when they want to declare local object without initializer, when there's nothing to initialize (e.g. a struct without non-static data members).
https://cplusplus.github.io/CWG/issues/253.html
https://cplusplus.github.io/CWG/issues/78.html