16struct WallCoarseClock
final {
18 using duration = std::chrono::system_clock::duration;
19 using rep = duration::rep;
20 using period = duration::period;
21 using time_point = std::chrono::system_clock::time_point;
23 static constexpr bool is_steady =
false;
25 static time_point now()
noexcept;
26 static duration resolution()
noexcept;