Inconsistent handling of enum raw values on the command line

[rgoldberg]

There seems to be inconsistent handling of enum raw values on the command line.

The following code is from CompletionScriptTests.swift:

enum Kind: String, ExpressibleByArgument, EnumerableFlag {
    case one, two
    case three = "custom-three"
}

@Flag var allowedKinds: [Kind] = []
@Option() var kind: Kind

case three = "custom-three" from above is considered as --three for a flag
from allowedKinds, but as custom-three as an option value for --kind.

This is the case in the 1.5.0 & main completion scripts, in ToolInfoV0 & even in SAP's
command-line argument verification. It seems to me that it should be consistent
throughout; of the 2 options, custom-three seems more sensible.

ArgumentParser version: main
Swift version:
swift-driver version: 1.120.5 Apple Swift version 6.1 (swiftlang-6.1.0.110.21 clang-1700.0.13.3)
Target: arm64-apple-macosx15.0

Checklist

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