tests/ui/parser/trait-object-bad-parens.rs

#![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 `+`
}