Validate conflicts_with

[HalfVoxel]

Make sure you completed the following tasks

• Searched the discussions
• Searched the closed issues

Describe your use case

Currently, it can sometimes be tricky to know which name to give to conflicts_with, in particular in combination with structopt.
Take a look at this issue for context: TeXitoi/structopt#459

Clap currently doesn't seem to care if conflicts_with is given a name which isn't even a valid field.

Describe the solution you'd like

Clap validates that the field conflicts_with is given actually exists.

[pksunkara]

Have you checked this with master? And also please provide a minimal sample code so it's easier for everyone.

[HalfVoxel]

I have not yet, my testing was done with clap v2.33.3 which is the latest stable version afaik (though I see that there's a 3.0 beta now).

I use structopt so that generates most of the code for me. You can find an example of that in the linked issue.

Here is the code that structopt generates which corresponds to this issue:

let app = app.about("Runs a module");
let app = app.arg(
    ::structopt::clap::Arg::with_name("module-name")
        .takes_value(true)
        .multiple(false)
        .validator(|s| {
            ::std::str::FromStr::from_str(s.as_str())
                .map(|_: String| ())
                .map_err(|e| e.to_string())
        })
        .help("Name of the cmdlet module to run")
        .short("n")
        .long("name"),
);
let app = app.arg(
    ::structopt::clap::Arg::with_name("module-cid")
        .takes_value(true)
        .multiple(false)
        .validator(|s| {
            ::std::str::FromStr::from_str(s.as_str())
                .map(|_: Cid| ())
                .map_err(|e| e.to_string())
        })
        .help("CID of the cmdlet module to run")
        .short("c")
        .long("cid")
        .conflicts_with("module_name"),
);
app.version("0.1.0")

Note that conflicts_with is given the name module_name while the generated name is actually module-name.

[pksunkara]

Can you please test it on clap master and report back?

[HalfVoxel]

Hi

I can confirm that this still happens with master.

[dependencies]
clap = { git = "https://github.com/clap-rs/clap.git", rev= "d7f6748" }

use clap::{App, Arg};

fn main() {
    let app = App::new("My Super Program")
        .about("Runs a module")
        .arg(
            Arg::new("module-name")
                .takes_value(true)
                .multiple(false)
                .short('n')
                .long("name"),
        )
        .arg(
            Arg::new("module-cid")
                .takes_value(true)
                .multiple(false)
                .short('c')
                .long("cid")
                .conflicts_with("module_name"),
        )
        .version("0.1.0");

    let matches = app.get_matches();
    println!("{:#?}", matches);
}

 ~/p/e/t/claptest (master) [2]> cargo run --release -- --name=NAME --cid=CID                                   (base)
   Compiling claptest v0.1.0 (/home/arong/projects/embark/test/claptest)
    Finished release [optimized] target(s) in 0.40s
     Running `target/release/claptest --name=NAME --cid=CID`
ArgMatches {
    args: {
        [hash: 49BCF4FC57DA0A4]: MatchedArg {
            occurs: 1,
            ty: CommandLine,
            indices: [
                1,
            ],
            vals: [],
        },
        [hash: 110F162FD0016129]: MatchedArg {
            occurs: 1,
            ty: CommandLine,
            indices: [
                2,
            ],
            vals: [],
        },
    },
    subcommand: None,
}

[epage]

This has since been resolved

We have an existing test conflicts_with_invalid_arg but I turned the above example code into a test to double check

#[cfg(debug_assertions)]
#[test]
#[should_panic]
fn non_existent_conflict_asserts() {
    App::new("My Super Program")
        .about("Runs a module")
        .arg(
            Arg::new("module-name")
                .takes_value(true)
                .multiple(false)
                .short('n')
                .long("name"),
        )
        .arg(
            Arg::new("module-cid")
                .takes_value(true)
                .multiple(false)
                .short('c')
                .long("cid")
                .conflicts_with("module_name"),
        )
        .version("0.1.0")
        .debug_assert();
}

And it passes on 3.0.0-rc.4