#![feature(no_core)] #![feature(lang_items)] #![no_core] #[lang = "sized"] trait Sized {} #[lang = "add"] trait Add<T> { const add: u32 = 1u32; } impl Add<u32> for u32 {} fn main() { 1u32 + 1u32; //~^ ERROR cannot add `u32` to `u32` }