Function atomic_compare_exchange 

#[doc(hidden)]
pub unsafe fn atomic_compare_exchange<T: Copy>(
    dst: *mut T,
    old: T,
    new: T,
    success: Ordering,
    failure: Ordering,
) -> Result<T, T>

🔬This is a nightly-only experimental API. (core_intrinsics)

Available on target_has_atomic only.

Publicly exposed for stdarch; nobody else should use this.