error: parse attribute is not allowed for flattened entry
  --> $DIR/flatten_and_parse.rs:22:21
   |
22 |     #[clap(flatten, parse(from_occurrences))]
   |                     ^^^^^

error[E0277]: the trait bound `Opt: std::convert::From<clap::parse::matches::arg_matches::ArgMatches>` is not satisfied
  --> $DIR/flatten_and_parse.rs:19:10
   |
19 | #[derive(Clap, Debug)]
   |          ^^^^ the trait `std::convert::From<clap::parse::matches::arg_matches::ArgMatches>` is not implemented for `Opt`