#![feature(auto_traits)] #![feature(negative_impls)] #![allow(bare_trait_objects)] auto trait Auto {} fn main() { let _: Box<((Auto)) + Auto>; //~ ERROR expected a path on the left-hand side of `+` let _: Box<(Auto + Auto) + Auto>; //~ ERROR expected a path on the left-hand side of `+` let _: Box<(Auto +) + Auto>; //~ ERROR expected a path on the left-hand side of `+` let _: Box<(dyn Auto) + Auto>; //~ ERROR expected a path on the left-hand side of `+` }