Since Gaudi v33r1, Gaudi provides compile-time checking of unchecked StatusCodes (via C++17
[[nodiscard]]). Gaudi v36r0 will deprecate all runtime checking related calls (gaudi/Gaudi!989 (merged)). In ATLAS we have not been using runtime-checking since quite some time (i.e. the
StatusCodeSvc is no longer part of any athena job).
This MR removes all remaining obsolete code that manually "checks" StatusCodes.