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//@compile-flags: -Zmiri-disable-weak-memory-emulation -Zmiri-preemption-rate=0 -Zmiri-disable-stacked-borrows
#![feature(new_uninit)]
use std::mem::MaybeUninit;
use std::ptr::null_mut;
use std::sync::atomic::{AtomicPtr, Ordering};
use std::thread::spawn;
#[derive(Copy, Clone)]
struct EvilSend<T>(pub T);
unsafe impl<T> Send for EvilSend<T> {}
unsafe impl<T> Sync for EvilSend<T> {}
pub fn main() {
// Shared atomic pointer
let pointer = AtomicPtr::new(null_mut::<MaybeUninit<usize>>());
let ptr = EvilSend(&pointer as *const AtomicPtr<MaybeUninit<usize>>);
// Note: this is scheduler-dependent
// the operations need to occur in
// order, otherwise the allocation is
// not visible to the other-thread to
// detect the race:
// 1. alloc
// 2. write
unsafe {
let j1 = spawn(move || {
let ptr = ptr; // avoid field capturing
// Concurrent allocate the memory.
// Uses relaxed semantics to not generate
// a release sequence.
let pointer = &*ptr.0;
pointer.store(Box::into_raw(Box::new_uninit()), Ordering::Relaxed);
});
let j2 = spawn(move || {
let ptr = ptr; // avoid field capturing
let pointer = &*ptr.0;
// Note: could also error due to reading uninitialized memory, but the data-race detector triggers first.
*pointer.load(Ordering::Relaxed) //~ ERROR: Data race detected between (1) Allocate on thread `<unnamed>` and (2) Read on thread `<unnamed>`
});
j1.join().unwrap();
j2.join().unwrap();
// Clean up memory, will never be executed
drop(Box::from_raw(pointer.load(Ordering::Relaxed)));
}
}
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