Show Docstrings of variants in ArgEnum in --help

[nipunn1313]

Please complete the following tasks

• I have searched the discussions
• I have searched the open and rejected issues

Clap Version

3.1.14

Describe your use case

Would like something like this:

#[derive(Parser, Debug)]
struct Args {
    /// Choice of variant
    #[clap(long, arg_enum)]
    v: Variants
}

#[derive(ArgEnum, Clone, Copy, Debug)]
pub enum Variants {
    /// Variant 1
    V1,
    /// Variant 2
    V2,
    /// Variant 3
    V3,
}

fn main() {
  let args = Args::parse();
}

Describe the solution you'd like

I would ideally like --help to show the description of the variants (V1, V2, V3).
Currently, it just shows the docstring for v: Variants

Alternatives, if applicable

Could also work to have this be gated behind a derive arg attribute on the struct

Additional Context

No response

[epage]

I believe this is a duplicate of #3312 which was implemented in #3503 which was released in 3.1.4.

It is gated behind unstable-v4 as we were uncomfortable with taking a doc string we previously ignored and starting to put it in the help.

[nipunn1313]

thanks! Appreciate the team behind clap

[hulxv]

I believe this is a duplicate of #3312 which was implemented in #3503 which was released in 3.1.4.

It is gated behind unstable-v4 as we were uncomfortable with taking a doc string we previously ignored and starting to put it in the help.

Is it possible to do it by derive way like that's example

#[derive(Parser, Debug)]
struct Args {
    /// Choice of variant
    #[clap(long, arg_enum)]
    v: Variants
}

#[derive(ArgEnum, Clone, Copy, Debug)]
pub enum Variants {
    /// Variant 1
    V1,
    /// Variant 2
    V2,
    /// Variant 3
    V3,
}

fn main() {
  let args = Args::parse();
}

or that's available for builder only now?

[epage]

Yes, the derive will automatically pick up doc comments. While the PR didn't explicitly add any code for that, it picked it up through shared code. I'm adding an explicit test for it.