error[E0038]: the trait `Bar` cannot be made into an object --> $DIR/issue-48027.rs:6:6 | LL | impl dyn Bar {} | ^^^^^^^ `Bar` cannot be made into an object | note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit --> $DIR/issue-48027.rs:2:11 | LL | trait Bar { | --- this trait cannot be made into an object... LL | const X: usize; | ^ ...because it contains this associated `const` = help: consider moving `X` to another trait error[E0790]: cannot refer to the associated constant on trait without specifying the corresponding `impl` type --> $DIR/issue-48027.rs:3:32 | LL | const X: usize; | --------------- `Bar::X` defined here LL | fn return_n(&self) -> [u8; Bar::X]; | ^^^^^^ cannot refer to the associated constant of trait error: aborting due to 2 previous errors Some errors have detailed explanations: E0038, E0790. For more information about an error, try `rustc --explain E0038`.