rust/tests/fail/data_race/fence_after_load.rs

// We want to control preemption here.
//@compile-flags: -Zmiri-disable-isolation -Zmiri-preemption-rate=0
use std::sync::atomic::{fence, AtomicUsize, Ordering};
use std::sync::Arc;
use std::thread;
use std::time::Duration;

fn main() {
    static mut V: u32 = 0;
    let a = Arc::new(AtomicUsize::default());
    let b = a.clone();
    thread::spawn(move || {
        unsafe { V = 1 }
        b.store(1, Ordering::SeqCst);
    });
    thread::sleep(Duration::from_millis(100));
    fence(Ordering::SeqCst);
    // Imagine the other thread's actions happening here.
    assert_eq!(a.load(Ordering::Relaxed), 1);
    // The fence is useless, since it did not happen-after the `store` in the other thread.
    // Hence this is a data race.
    // Also see https://github.com/rust-lang/miri/issues/2192.
    unsafe { V = 2 } //~ERROR: Data race detected between Write on thread `main` and Write on thread `<unnamed>`
}