Short name option '-h' (conflicting with built-in help) is allowed, with strange results.

[psummerland]

Checklist

• [ x] If possible, I've reproduced the issue using the main branch of this package
• [ x] I've searched for existing GitHub issues

Steps to Reproduce

Add the horse option to the Repeat example provided with swift-argument-parser:

 @main
struct Repeat: ParsableCommand {
    @Option(name: .shortAndLong, help: "The number of times to repeat 'phrase'.")
    var count: Int? = nil

    @Option(name: .shortAndLong, help: "The name of the talking horse.")
    var horse: String

    @Flag(name: .shortAndLong,  help: "Include a counter with each repetition.")
    var includeCounter = false

    @Argument(help: "The phrase to repeat.")
    var phrase: String

    mutating func run() throws {

        let repeatCount = count ?? 2

        for i in 1...repeatCount {
            if includeCounter {
                print("\(i): \(horse) says: \"\(phrase)\"")
            } else {
                print(phrase)
            }
        }
    }
}

Actual behavior

Help shows conflicting descriptions for "-h":

USAGE: repeat [--count <count>] [--include-counter] <phrase> --horse <horse>

ARGUMENTS:
  <phrase>                The phrase to repeat.

OPTIONS:
  -c, --count <count>     The number of times to repeat 'phrase'.
  -i, --include-counter   Include a counter with each repetition.
  -h, --horse <horse>     The name of the speaking horse.
  -h, --help              Show help information.

Works sometimes:

release> ./repeat --horse Secretariat "I trained hard and won." -i
1: Secretariat says: "I trained hard and won."
2: Secretariat says: "I trained hard and won."

What does "-h" mean?

release> ./repeat -h
Error: Missing value for '-h <horse>'
Help:  -h <horse>  The name of the speaking horse.
Usage: repeat [--count <count>] --horse <horse> [--include-counter] <phrase>
  See 'repeat --help' for more information.

Seems to mean the same as "--horse", so add the value:

release> ./repeat -h Secretariat
USAGE: repeat [--count <count>] --horse <horse> [--include-counter] <phrase>

ARGUMENTS:
  <phrase>                The phrase to repeat.

OPTIONS:
  -c, --count <count>     The number of times to repeat 'phrase'.
  -h, --horse <horse>     The name of the speaking horse.
  -i, --include-counter   Include a counter with each repetition.
  -h, --help              Show help information.

Hm - now it seems to means "--help"

Expected behavior

I expected the program to stop immediately with a fatal error. (I assume that
the conflict cannot be detected at compile time.)

By the way.

One might consider modifying the current version of Repeat to avoid this:

release> ./repeat -c 0 hello
fish: Job 1, './repeat -c 0 hello' terminated by signal SIGTRAP (Trace or breakpoint trap)

No big deal.

[rgoldberg]

I would expect the auto-generated help subcommand to be added as a child of a (sub)command only if it doesn't already have an existing subcommand named help.

I would expect --help to only be added if no existing flag or option already has that name.

I would expect -h to only be added if no existing flag or option already has that name.

I would also expect being able to manually prevent any of the help (or version) interface from being added. I don't know if that's possible.

[natecook1000]

I would expect the auto-generated help subcommand to be added as a child of a (sub)command only if it doesn't already have an existing subcommand named help.

I would expect --help to only be added if no existing flag or option already has that name.

I would expect -h to only be added if no existing flag or option already has that name.

We could treat all of these as bug fixes, since the existing behavior is so unstable.

I would also expect being able to manually prevent any of the help (or version) interface from being added. I don't know if that's possible.

Specifying an empty array for helpNames in a command's configuration suppresses the -h and --help access for the help screen, but I don't think there's a way to prevent the command help subcommand-style help screen for hierarchical commands.