warning: trait objects without an explicit `dyn` are deprecated
  --> $DIR/lint-group-allowed-cli-warn-by-default-lint.rs:8:25
   |
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/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
   = note: `--force-warn bare-trait-objects` implied by `--force-warn rust-2018-idioms`
   = help: to override `--force-warn rust-2018-idioms` add `#[allow(bare_trait_objects)]`
help: if this is an object-safe trait, use `dyn`
   |
LL | pub fn function(_x: Box<dyn SomeTrait>) {}
   |                         +++

warning: 1 warning emitted