Struct std::TaskHeader

struct TaskHeader {
    int state;
    ?&TaskHeader next;
    struct WakerSlot joiner;
    struct Spinlock lock;
}

The part of an AsyncTask an executor sees. First field of every AsyncTask, so a ?&TaskHeader and the task have the same address: poll_ and drop_ are AsyncTask<F, T>'s own functions, stored by AsyncTask::new as functions of the header (see std/erased.h).