Flattened enum panics when no subcommand is supplied

[Jokler]

#[derive(StructOpt, Debug)]
struct Opt {
    #[structopt(short = "f")]
    foo: Option<String>,
    #[structopt(flatten)]
    sub_opt: SubOpt,
}

#[derive(StructOpt, Debug)]
enum SubOpt {
    Foo,
    Bar,
}

fn main() {
    let opt = Opt::from_args();
    println!("{:#?}", opt);
}

$ cargo run -- Foo
    Finished dev [unoptimized + debuginfo] target(s) in 0.0 secs
     Running `target\debug\structopt-test.exe Foo`
Opt {
    foo: None,
    sub_opt: Foo
}

$ cargo run
    Finished dev [unoptimized + debuginfo] target(s) in 0.0 secs
     Running `target\debug\structopt-test.exe`
thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', libcore\option.rs:335:21
note: Run with `RUST_BACKTRACE=1` for a backtrace.
error: process didn't exit successfully: `target\debug\structopt-test.exe` (exit code: 101)

In clap I used AppSettings::SubcommandRequiredElseHelp for the behaviour I wanted and I expected something similar when I wrote this.

[TeXitoi]

This is a bug as it should never panic, but using flatten on an enum is quite meaningless. What do you want to do? isn't more subcommand that you want instead of flatten?

[TeXitoi]

Fixed in v0.2.8

[Jokler]

Yes, I do want subcommands but also the other Option.
Is there a better way to accomplish this?

Good to hear that it is fixed. :)

[TeXitoi]

In your example, using subcommand instead of flatten will do what you want. Now, with the corrected version, flatten and subcommand will do the exact same thing.

[Jokler]

Ok, I see what you mean - thanks.