Requirement on only one entry of a group

[jwildstr-ibm]

I'm trying to implement something where there's extra parameters for only one type of a group of mutually exclusive arguments (the "type" of the application target). If I specify --extra with no "type" parameter, it properly prompts me for --type-b, but if I give another type, it just allows it to run.

Simple code:

use clap::{ArgGroup, Parser};

#[derive(Parser, Debug)]
#[command(version, about, long_about=None)]
#[clap(group(
    ArgGroup::new("type")
        .required(false)
        .args(&["type_a", "type_b", "type_c"]),
))]
struct Args {
    /// Type-A run
    #[arg(long)]
    type_a: bool,

    /// Type-B run
    #[arg(long)]
    type_b: bool,

    /// Type-C run
    #[arg(long)]
    type_c: bool,

    /// Extra info for Type B
    #[arg(long, requires = "type_b")]
    extra: Option<String>,
}

fn main() {
    let args = Args::parse();
    println!("{:?}", args);
}

When I run in the "bad" form, I see:

$ cargo run -- --type-a --extra foo
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.02s
     Running `target/debug/clap-test --type-a --extra foo`
Args { type_a: true, type_b: false, type_c: false, extra: Some("foo") }

What am I doing wrong here? Is this a bug, or a misunderstanding about how I should use things?

[epage]

This is a known issue. Conflicts override all forms of required. The main issue where this is being examined is #4520 with the group-specific variant being tracked in #4707.