src/test/ui/rfc-2632-const-trait-impl/call-const-trait-method-pass.rs

// run-pass

#![allow(incomplete_features)]
#![feature(const_trait_impl)]
#![feature(const_fn)]

struct Int(i32);

impl const std::ops::Add for Int {
    type Output = Int;

    fn add(self, rhs: Self) -> Self {
        Int(self.0.plus(rhs.0))
    }
}

impl const PartialEq for Int {
    fn eq(&self, rhs: &Self) -> bool {
        self.0 == rhs.0
    }
}

pub trait Plus {
    fn plus(self, rhs: Self) -> Self;
}

impl const Plus for i32 {
    fn plus(self, rhs: Self) -> Self {
        self + rhs
    }
}

pub const fn add_i32(a: i32, b: i32) -> i32 {
    a.plus(b)
}

const ADD_INT: Int = Int(1i32) + Int(2i32);

fn main() {
    assert!(ADD_INT == Int(3i32));
}