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    use std::cell::UnsafeCell;
    use std::fmt;
    use std::ops;

    /// `AtomicUsize` providing an additional `load_unsync` function.
    pub(crate) struct AtomicUsize {
        inner: UnsafeCell<std::sync::atomic::AtomicUsize>,
    }

    unsafe impl Send for AtomicUsize {}
    unsafe impl Sync for AtomicUsize {}

    impl AtomicUsize {
        pub(crate) const fn new(val: usize) -> AtomicUsize {
            let inner = UnsafeCell::new(std::sync::atomic::AtomicUsize::new(val));
            AtomicUsize { inner }
        }

        /// Performs an unsynchronized load.
        ///
        /// # Safety
        ///
        /// All mutations must have happened before the unsynchronized load.
        /// Additionally, there must be no concurrent mutations.
        pub(crate) unsafe fn unsync_load(&self) -> usize {
            *(*self.inner.get()).get_mut()
        }

        pub(crate) fn with_mut<R>(&mut self, f: impl FnOnce(&mut usize) -> R) -> R {
            // safety: we have mutable access
            f(unsafe { (*self.inner.get()).get_mut() })
        }
    }

    impl ops::Deref for AtomicUsize {
        type Target = std::sync::atomic::AtomicUsize;

        fn deref(&self) -> &Self::Target {
            // safety: it is always safe to access `&self` fns on the inner value as
            // we never perform unsafe mutations.
            unsafe { &*self.inner.get() }
        }
    }

    impl ops::DerefMut for AtomicUsize {
        fn deref_mut(&mut self) -> &mut Self::Target {
            // safety: we hold `&mut self`
            unsafe { &mut *self.inner.get() }
        }
    }

    impl fmt::Debug for AtomicUsize {
        fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
            (**self).fmt(fmt)
        }
    }