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mod old_impl {
    #[rustversion::before(1.34)]
    use std::{cmp::Ordering, fmt, num::*};

    #[allow(unused)]
    macro_rules! impl_nonzero_fmt {
        ( ( $( $Trait: ident ),+ ) for $Ty: ident ) => {
            $(
                impl fmt::$Trait for $Ty {
                    #[inline]
                    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
                        self.get().fmt(f)
                    }
                }
            )+
        }
    }

    #[allow(unused)]
    macro_rules! def_signed {
        ( $($name:ident($inner:ident, $zeroable_signed:ident, $zeroable:ident),)+) => {
            $(
                /// An integer that is known not to equal zero.
                ///
                /// This enables some memory layout optimization.
                /// For example, `Option<NonZeroI32>` is the same size as `i32`:
                ///
                /// ```rust
                /// use std::mem::size_of;
                /// use nonzero_signed::NonZeroI32;
                /// assert_eq!(size_of::<Option<NonZeroI32>>(), size_of::<i32>());
                /// ```
                #[derive(Copy, Clone, Eq, PartialEq, Hash)]
                #[repr(transparent)]
                pub struct $name($inner);

                impl $name {
                    /// Create a non-zero without checking the value.
                    ///
                    /// # Safety
                    ///
                    /// The value must not be zero.
                    #[inline]
                    pub unsafe fn new_unchecked(n: $zeroable_signed) -> Self {
                        $name($inner::new_unchecked(n as $zeroable))
                    }

                    /// Create a non-zero if the given value is not zero.
                    #[inline]
                    pub fn new(n: $zeroable_signed) -> Option<Self> {
                        if n != 0 {
                            Some(unsafe {$name::new_unchecked(n)})
                        } else {
                            None
                        }
                    }

                    /// Returns the value as a primitive type.
                    #[inline]
                    pub fn get(self) -> $zeroable_signed {
                        self.0.get() as $zeroable_signed
                    }
                }

                impl Ord for $name {
                    fn cmp(&self, other: &Self) -> Ordering {
                        self.get().cmp(&other.get())
                    }
                }

                impl PartialOrd for $name {
                    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
                        Some(self.cmp(other))
                    }
                }

                impl_nonzero_fmt! {
                    (Debug, Display, Binary, Octal, LowerHex, UpperHex) for $name
                }
            )+
        }
    }

    #[rustversion::before(1.34)]
    def_signed!(
        NonZeroI8(NonZeroU8, i8, u8),
        NonZeroI16(NonZeroU16, i16, u16),
        NonZeroI32(NonZeroU32, i32, u32),
        NonZeroI64(NonZeroU64, i64, u64),
        NonZeroI128(NonZeroU128, i128, u128),
        NonZeroIsize(NonZeroUsize, isize, usize),
    );
}

#[rustversion::before(1.34)]
pub use old_impl::*;

#[rustversion::since(1.34)]
pub use std::num::{NonZeroI128, NonZeroI16, NonZeroI32, NonZeroI64, NonZeroI8, NonZeroIsize};

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn wrapping_test() {
        assert!(NonZeroI8::new(0).is_none());
        assert!(NonZeroI8::new(-5).unwrap().get() == -5);
    }

    #[test]
    fn format_test() {
        assert_eq!(format!("{}", NonZeroI8::new(-5).unwrap()), "-5")
    }
}