Clap either -a OR (-b AND -c) arguments

[graffic]

I'm trying to get clap 3.2 to validate and show help correctly for the following scenario: give a token OR give username AND password.

With the current configuration I got the validation right, but the help is not very indicative of the validation.

#[derive(Parser)]
#[clap(group(
    ArgGroup::new("auth")
        .required(true)
        .multiple(false)
        .args(&["token","username"])
))]
pub struct Cli {
    #[clap(long, requires = "password")]
    pub username: Option<String>,

    #[clap(long, requires = "username")]
    pub password: Option<String>,

    /// Authentication token (replaces username and password)
    #[clap(long)]
    pub token: Option<String>,
}

Is this the closest I can get to token OR username AND password or there is a better way?

The current configuration falls a bit short when no option is given, that is not said that not only username is needed but the password too:

error: The following required arguments were not provided:
    <--token <TOKEN>|--username <USERNAME>>

Or if only --password is given, the same message is given.

[spencerwhite]

You could try to make it more robust by specifically asking the user for missing arguments. For example, if the user only enters -username, it should pop up with a dialog that asks for the password.

Or, (and I'm not sure if Clap allows this), you could have a single argument like -login that takes both a username and a password, but that's probably less readable.

[graffic]

The current configuration does that. If you only input --username it asks for:

error: The following required arguments were not provided:
    --password <PASSWORD>