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    use std::ops::{Add, Mul};
    use std::num::Wrapping;

    /// Defines an additive identity element for `Self`.
    pub trait Zero: Sized + Add<Self, Output = Self> {
        /// Returns the additive identity element of `Self`, `0`.
        ///
        /// # Laws
        ///
        /// ```{.text}
        /// a + 0 = a       ∀ a ∈ Self
        /// 0 + a = a       ∀ a ∈ Self
        /// ```
        ///
        /// # Purity
        ///
        /// This function should return the same result at all times regardless of
        /// external mutable state, for example values stored in TLS or in
        /// `static mut`s.
        // FIXME (#5527): This should be an associated constant
        fn zero() -> Self;

        /// Returns `true` if `self` is equal to the additive identity.
        #[inline]
        fn is_zero(&self) -> bool;
    }

    macro_rules! zero_impl {
        ($t:ty, $v:expr) => {
            impl Zero for $t {
                #[inline]
                fn zero() -> $t { $v }
                #[inline]
                fn is_zero(&self) -> bool { *self == $v }
            }
        }
    }

    zero_impl!(usize, 0usize);
    zero_impl!(u8,    0u8);
    zero_impl!(u16,   0u16);
    zero_impl!(u32,   0u32);
    zero_impl!(u64,   0u64);

    zero_impl!(isize, 0isize);
    zero_impl!(i8,    0i8);
    zero_impl!(i16,   0i16);
    zero_impl!(i32,   0i32);
    zero_impl!(i64,   0i64);

    zero_impl!(f32, 0.0f32);
    zero_impl!(f64, 0.0f64);

    impl<T: Zero> Zero for Wrapping<T> where Wrapping<T>: Add<Output=Wrapping<T>> {
        fn is_zero(&self) -> bool {
            self.0.is_zero()
        }
        fn zero() -> Self {
            Wrapping(T::zero())
        }
    }

    /// Defines a multiplicative identity element for `Self`.
    pub trait One: Sized + Mul<Self, Output = Self> {
        /// Returns the multiplicative identity element of `Self`, `1`.
        ///
        /// # Laws
        ///
        /// ```{.text}
        /// a * 1 = a       ∀ a ∈ Self
        /// 1 * a = a       ∀ a ∈ Self
        /// ```
        ///
        /// # Purity
        ///
        /// This function should return the same result at all times regardless of
        /// external mutable state, for example values stored in TLS or in
        /// `static mut`s.
        // FIXME (#5527): This should be an associated constant
        fn one() -> Self;
    }

    macro_rules! one_impl {
        ($t:ty, $v:expr) => {
            impl One for $t {
                #[inline]
                fn one() -> $t { $v }
            }
        }
    }

    one_impl!(usize, 1usize);
    one_impl!(u8,    1u8);
    one_impl!(u16,   1u16);
    one_impl!(u32,   1u32);
    one_impl!(u64,   1u64);

    one_impl!(isize, 1isize);
    one_impl!(i8,    1i8);
    one_impl!(i16,   1i16);
    one_impl!(i32,   1i32);
    one_impl!(i64,   1i64);

    one_impl!(f32, 1.0f32);
    one_impl!(f64, 1.0f64);

    impl<T: One> One for Wrapping<T> where Wrapping<T>: Mul<Output=Wrapping<T>> {
        fn one() -> Self {
            Wrapping(T::one())
        }
    }

    // Some helper functions provided for backwards compatibility.

    /// Returns the additive identity, `0`.
    #[inline(always)] pub fn zero<T: Zero>() -> T { Zero::zero() }

    /// Returns the multiplicative identity, `1`.
    #[inline(always)] pub fn one<T: One>() -> T { One::one() }

    macro_rules! test_wrapping_identities {
        ($($t:ty)+) => {
            $(
                assert_eq!(zero::<$t>(), zero::<Wrapping<$t>>().0);
                assert_eq!(one::<$t>(), one::<Wrapping<$t>>().0);
                assert_eq!((0 as $t).is_zero(), Wrapping(0 as $t).is_zero());
                assert_eq!((1 as $t).is_zero(), Wrapping(1 as $t).is_zero());
            )+
        };
    }

    #[test]
    fn wrapping_identities() {
        test_wrapping_identities!(isize i8 i16 i32 i64 usize u8 u16 u32 u64);
    }

    #[test]
    fn wrapping_is_zero() {
        fn require_zero<T: Zero>(_: &T) {}
        require_zero(&Wrapping(42));
    }
    #[test]
    fn wrapping_is_one() {
        fn require_one<T: One>(_: &T) {}
        require_one(&Wrapping(42));
    }

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