|  | warning: trait objects without an explicit `dyn` are deprecated | 
|  | --> $DIR/lint-group-allowed-warn-by-default-lint.rs:10:25 | 
|  | | | 
|  | LL | pub fn function(_x: Box<SomeTrait>) {} | 
|  | |                         ^^^^^^^^^ | 
|  | | | 
|  | = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021! | 
|  | = note: for more information, see <https://doc.rust-lang.org/edition-guide/rust-2021/warnings-promoted-to-error.html> | 
|  | = note: `--force-warn bare-trait-objects` implied by `--force-warn rust-2018-idioms` | 
|  | help: if this is a dyn-compatible trait, use `dyn` | 
|  | | | 
|  | LL | pub fn function(_x: Box<dyn SomeTrait>) {} | 
|  | |                         +++ | 
|  |  | 
|  | warning: 1 warning emitted | 
|  |  |