clap_complete command arguments completion from existing commands.

[TomPlanche]

Let's say I build a wrapper around the git commit method.

#[derive(Subcommand)]
pub(crate) enum CliCommand {
    /// Directly commit the file with the text in `commit_message.md`.
    #[command(short_flag = 'c')]
    Commit {
        /// Whether to push the commit after committing
        #[arg(short = 'p', long = "push", default_value_t = false)]
        push: bool,

        /// Show what would be committed without actually committing
        #[arg(long, default_value_t = false)]
        dry_run: bool,

        /// Additional arguments to pass to the commit command
        #[arg(allow_hyphen_values = true)]
        args: Vec<String>,
    },

    /// Generate shell completions for your shell
    #[command(name = "completion")]
    Completion {
        /// The shell to generate completions for
        #[arg(value_enum)]
        shell: Shell,
    },
}

#[derive(Parser)]
#[command(version)]
pub(crate) struct Cli {
    #[command(subcommand)]
    command: CliCommand,
}

Can I add a derive macro attribute to the args: Vec<String>, in order to offer/autocomplete the sames arguments as the git commit command ?

[epage]

At this time, no.

I would love to have support for ways to delegate completions. This would help with plugin systems as well, like cargo release using cargo-release release for completions.

I would prefer a solution to focus on our new completion system. I am not to familiar with the different completion systems to be able to move something like this forward. If it requires users to provide shell specific glue code, we can use the plugin system we added for native completions to attach arbitrary data to a Command or an Arg.