#![feature(const_generics, const_evaluatable_checked)] #![allow(incomplete_features)] const fn bar() -> usize { 7 } trait Foo { fn test(&self) -> [u8; bar::()]; } impl Foo for () { fn test(&self) -> [u8; bar::()] { [0; bar::()] } } fn use_dyn(v: &dyn Foo) { //~ERROR the trait `Foo` cannot be made into an object v.test(); } fn main() {}