How to return an error when the value of another argument is unexpected

[sorairolake]

Hi,

I want to return an error if an argument is specified, but the value of another argument is unexpected.

# OK
$ cmd --http2
$ cmd --http3
$ cmd --http3 --http3-only

# Error
$ cmd --http3-only
$ cmd --http2 --http3-only

#[derive(Debug, Parser)]
#[command(version, about)]
pub struct Opt {
    #[arg(long, conflicts_with("http3"))]
    pub http2: bool,

    #[arg(long)]
    pub http3: bool,

    #[arg(long, requires("http3"))]
    pub http3_only: bool,
}

How can I make the following example work like the above?

# OK
$ cmd --http-version=2
$ cmd --http-version=3
$ cmd --http-version=3 --http3-only

# Error
$ cmd --http3-only
$ cmd --http-version=2 --http3-only

#[derive(Debug, Parser)]
#[command(version, about)]
pub struct Opt {
    #[arg(long, value_enum)]
    pub http_version: HttpVersion,

    // How can I change the following attributes?
    #[arg(long)]
    pub http3_only: bool,
}

#[derive(Clone, Debug, ValueEnum)]
pub enum HttpVersion {
    #[clap(name = "2")]
    Http2,

    #[clap(name = "3")]
    Http3,
}

[epage]

We do not support this at this time and it would require having a check in your application after parsing.
We have requires_if but it is the opposite of what you want.