Returns whether the associated Once was poisoned prior to the invocation of the closure passed to call_once_force.

Examples

A poisoned Once:

#![feature(once_poison)]

use std::sync::{Once, ONCE_INIT};
use std::thread;

static INIT: Once = ONCE_INIT;

// poison the once
let handle = thread::spawn(|| {
    INIT.call_once(|| panic!());
});
assert!(handle.join().is_err());

INIT.call_once_force(|state| {
    assert!(state.poisoned());
});

An unpoisoned Once:

#![feature(once_poison)]

use std::sync::{Once, ONCE_INIT};

static INIT: Once = ONCE_INIT;

INIT.call_once_force(|state| {
    assert!(!state.poisoned());
});

Formats the value using the given formatter. Read more