Status

    const Status = packed struct(usize) {
        /// The specific values of these enum fields are chosen to simplify the implementation of
        /// the transformations we need to apply to this state.
        cancelation: enum(u3) {
            /// The thread has not yet been canceled, and is not in a cancelable operation.
            /// To request cancelation, just set the status to `.canceling`.
            none = 0b000,

            /// The thread is parked in a cancelable futex wait or sleep.
            /// Only applicable if `use_parking_futex` or `use_parking_sleep`.
            /// To request cancelation, set the status to `.canceling` and unpark the thread.
            /// To unpark for another reason (futex wake), set the status to `.none` and unpark the thread.
            parked = 0b001,

            /// The thread is blocked in a cancelable system call.
            /// To request cancelation, set the status to `.blocked_canceling` and repeatedly interrupt the system call until the status changes.
            blocked = 0b011,

            /// Windows-only: the thread is blocked in an alertable wait via
            /// `NtDelayExecution`. To request cancelation, set the status to
            /// `blocked_alertable_canceling` and repeatedly alert the thread
            /// until the status changes.
            blocked_alertable = 0b010,

            /// The thread has an outstanding cancelation request but is not in a cancelable operation.
            /// When it acknowledges the cancelation, it will set the status to `.canceled`.
            canceling = 0b110,

            /// The thread has received and acknowledged a cancelation request.
            /// If `recancel` is called, the status will revert to `.canceling`, but otherwise, the status
            /// will not change for the remainder of this task's execution.
            canceled = 0b111,

            /// The thread is blocked in a cancelable system call, and is being
            /// canceled. The thread which triggered the cancelation will send
            /// signals to this thread until its status changes.
            blocked_canceling = 0b101,

            /// Windows-only: the thread is blocked in an alertable wait via
            /// `NtDelayExecution`, and is being canceled. The thread which
            /// triggered the cancelation will send signals to this thread
            /// until its status changes.
            blocked_alertable_canceling = 0b100,
        },

        /// We cannot turn this value back into a pointer. Instead, it exists so that a task can be
        /// canceled by a cmpxchg on thread status: if it is running the task we want to cancel,
        /// then update the `cancelation` field.
        awaitable: AwaitableId,
    }