`<future>` enums

future_errc Enumeration

Supplies symbolic names for all of the errors that are reported by the future_error class.

class future_errc {
   broken_promise,
   future_already_retrieved,
   promise_already_satisfied,
   no_state
   };

Supplies symbolic names for the reasons that a timed wait function can return.

enum future_status{
    ready,
    timeout,
    deferred
};

Represents a bitmask type that describes the possible modes for the template function async.

class launch{
   async,
   deferred
   };