warning: trait objects without an explicit `dyn` are deprecated
  --> $DIR/force-warn-group-allow-warning.rs:8:25
   |
LL | pub fn function(_x: Box<SomeTrait>) {}
   |                         ^^^^^^^^^ help: use `dyn`: `dyn SomeTrait`
   |
   = note: warning forced by `force-warns` commandline option
   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2021 edition!
   = note: for more information, see issue #80165 <https://github.com/rust-lang/rust/issues/80165>

warning: 1 warning emitted