error[E0277]: the trait bound `SubCmd: Subcommand` is not satisfied
 --> tests/derive_ui/flatten_struct_in_enum.rs:4:9
  |
4 |     Sub(SubCmd),
  |         ^^^^^^ the trait `Subcommand` is not implemented for `SubCmd`
  |
  = help: the following other types implement trait `Subcommand`:
            Box<T>
            Opt