Crate ref_ops

Expand description

An escape hatch for implementing ops traits for references to newtypes.

As of Rust 1.65.0, the following code does not compile:

use core::ops::Neg;

struct A<T>(T);

impl<'a, T, O> Neg for &'a A<T>
where
    &'a T: Neg<Output = O>,
{
    type Output = A<O>;

    fn neg(self) -> Self::Output {
        A(-&self.0)
    }
}

fn f<T>(a: T)
where
    for<'a> &'a T: Neg,
{
    let minus_a = -&a;

    // to do something with `a` and `minus_a`
}

fn g<T>(a: T)
where
    for<'a> &'a T: Neg,
{
    f(a);
}

but the following code does:

use core::ops::Neg;
use ref_ops::RefNeg;

struct A<T>(T);

impl<T> Neg for &A<T>
where
    T: RefNeg,
{
    type Output = A<T::Output>;

    fn neg(self) -> Self::Output {
        A(self.0.ref_neg())
    }
}

fn f<T>(a: T)
where
    for<'a> &'a T: Neg,
{
    let minus_a = -&a;

    // to do something with `a` and `minus_a`
}

fn g<T>(a: T)
where
    for<'a> &'a T: Neg,
{
    f(a);
}