#include <compare> // see [compare.syn] namespace std { class thread; void swap(thread& x, thread& y) noexcept; // [thread.jthread.class] class jthread class jthread; namespace this_thread { thread::id get_id() noexcept; void yield() noexcept; template<class Clock, class Duration> void sleep_until(const chrono::time_point<Clock, Duration>& abs_time); template<class Rep, class Period> void sleep_for(const chrono::duration<Rep, Period>& rel_time); } }