clap generates invalid bash completions for ArgEnum

[ajeetdsouza]

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• I have searched the discussions
• I have searched the existing issues

Rust Version

rustc 1.52.1 (9bc8c42bb 2021-05-09)

Clap Version

3.0.0-beta.2

Minimal reproducible code

use clap::{ArgEnum, Clap, IntoApp};

#[derive(Clap, Debug)]
pub struct App {
    #[clap(arg_enum)]
    pub shell: Shell,
}

#[derive(ArgEnum, Debug)]
pub enum Shell {
    Bash,
    Fish,
    Zsh,
}

fn main() {
    let mut app = App::into_app();
    clap_generate::generate::<clap_generate::generators::Bash, _>(
        &mut app,
        "play",
        &mut std::io::stdout(),
    );
}

Steps to reproduce the bug with the above code

cargo run

Actual Behaviour

Assuming a binary name of foo, if I type in fooTab, I get the following completions:

-h         --help     <shell>    -V         --version

Expected Behaviour

The <shell> value is a placeholder, it's not supposed to be used in completions.

I should have gotten the options of bash, fish, zsh instead.

Additional Context

The full generated bash completions are:

_play() {
    local i cur prev opts cmds
    COMPREPLY=()
    cur="${COMP_WORDS[COMP_CWORD]}"
    prev="${COMP_WORDS[COMP_CWORD-1]}"
    cmd=""
    opts=""

    for i in ${COMP_WORDS[@]}
    do
        case "${i}" in
            play)
                cmd="play"
                ;;
            
            *)
                ;;
        esac
    done

    case "${cmd}" in
        play)
            opts=" -h -V  --help --version  <shell> "
            if [[ ${cur} == -* || ${COMP_CWORD} -eq 1 ]] ; then
                COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                return 0
            fi
            case "${prev}" in
                
                *)
                    COMPREPLY=()
                    ;;
            esac
            COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
            return 0
            ;;
        
    esac
}

complete -F _play -o bashdefault -o default play

Debug Output

No response