Return true if *this refers to a stop state on which request_stop has been called, and false otherwise. If this function returns true, then the successful call to request_stop synchronizes with this call. A call to stop_requested that is potentially concurrent with a call to stop_requested or stop_possible does not cause a data race.
Declared in <bslstl_stoptoken.h>
[[nodiscard]]
bool
stop_requested() const noexcept;
The return value should not be discarded.