src/test/ui/rfc-2632-const-trait-impl/const-trait-bound-opt-out/in-trait-bounds.rs

#![feature(const_trait_bound_opt_out)]
#![allow(incomplete_features)]

trait Super {}
trait T: ?const Super {}
//~^ ERROR `?const` is not permitted in supertraits
//~| ERROR `?const` on trait bounds is not yet implemented

fn main() {}