The require_unless_one only works for the first argument name in array

[volks73]

Let me start by saying that this library (crate) is amazing. It has been a lot of fun creating small CLI applications with Rust and this library. This is also my first time submitting an issue on Github.

I have been trying to use the require_unless_one function for an argument. It appears to only work for the first argument name in the array. From the documentation, this works:

let res = App::new("unlessone")
    .arg(Arg::with_name("cfg")
        .required_unless_one(&["dbg", "infile"])
        .takes_value(true)
        .long("config"))
    .arg(Arg::with_name("dbg")
        .long("debug"))
    .arg(Arg::with_name("infile")
        .short("i")
        .takes_value(true))
    .get_matches_from_safe(vec![
        "unlessone", "--debug"
    ]);

    assert!(res.is_ok());
    let m = res.unwrap();
    assert!(m.is_present("dbg"));
    assert!(!m.is_present("cfg"));

But the following does not appear to work:

let res = App::new("unlessone")
    .arg(Arg::with_name("cfg")
        .required_unless_one(&["dbg", "infile"])
        .takes_value(true)
        .long("config"))
    .arg(Arg::with_name("dbg")
        .long("debug"))
    .arg(Arg::with_name("infile")
        .short("i")
        .takes_value(true))
    .get_matches_from_safe(vec![
        "unlessone", "-i", "file"
    ]);

    assert!(res.is_ok());
    let m = res.unwrap();
    assert!(m.is_present("infile"));
    assert!(!m.is_present("cfg"));

Note, I have specified the infile argument, which is the second value in the array for the required_unless_one function. I have forked the repository and added a test for the second example. It currently fails. I have not had a chance to find the issue in the source code yet, but I thought I could at least submit an issue and a pull request that adds the test.

I am using the latest release version of clap (v2.9.2) on Mac OSX with Rust 1.9.0 stable.

[kbknapp]

Thanks for filing this, and also the PR 😉 I apologize for the time it's taken me to get to this; I've been traveling for my job. I'm going to look through your PR and we should be able to get this fixed quickly. 👍

[kbknapp]

#595 fixes this