how to control OPTIONS listing ordering?

[jtmoon79]

tl;dr Clap --help message lists options alphabetically. I'd prefer to list some options, like --version, last.

When passing --help to a clap derived CLI parser, the listing of options --help and --version is in alphabetical order.

Given src/main.rs (rust playground)

extern crate clap;
use clap::Parser;

#[derive(Parser, Debug)]
#[clap(author, version, about)]
struct Args {
    /// path args
    #[clap(parse(from_os_str))]
    paths: Vec::<std::path::PathBuf>,

    /// an optional number
    #[clap(short, long, default_value_t = 1)]
    number1: u64,

    /// an optional number
    #[clap(short, long, default_value_t = 2)]
    anumber2: u64,

    /// an optional flag
    #[clap(short, long)]
    option1: bool,
}

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

and Cargo.toml

[package]
name = "test4-clap-help"
version = "0.1.0"
edition = "2021"

[dependencies]
clap = { version = "3.1.6", features = ["derive"] }

The cargo run -- --help output is:

test4-clap-help 0.1.0

USAGE:
    test4-clap-help [OPTIONS] [PATHS]...

ARGS:
    <PATHS>...    path args

OPTIONS:
    -a, --anumber2 <ANUMBER2>    an optional number [default: 2]
    -h, --help                   Print help information
    -n, --number1 <NUMBER1>      an optional number [default: 1]
    -o, --option1                an optional flag
    -V, --version                Print version information

I would like to move --help and --version to the bottom of the OPTIONS listing. I don't like to intermix meta-informational options (--help, --version) with purposeful options (--anumber, etc.). As a program user, it's confusing to read in this order.

How can I control the ordering of listed OPTIONS? Does the clap derive offer a grouping mechanism that understands ordering?

[jtmoon79]

Set the DeriveDisplayOrder.

#[clap(setting = clap::AppSettings::DeriveDisplayOrder)]
struct Args {
...

[epage]

FYI we plan to make this the default in clap4
#2808