Fix binary compatibility for HasCliOptions.CliOption

[jackkoenig]

You can see the failures in #5028

Contributor Checklist

• Did you add Scaladoc to every public function/method?
• Did you add at least one test demonstrating the PR?
• Did you delete any extraneous printlns/debugging code?
• Did you specify the type of improvement?
• Did you add appropriate documentation in docs/src?
• Did you request a desired merge strategy?
• Did you add text to be included in the Release Notes for this change?

Type of Improvement

• Bugfix

Marked No Release Notes because this binary compatibility issue is not yet released.

Desired Merge Strategy

• Squash

Release Notes

Reviewer Checklist (only modified by reviewer)

• Did you add the appropriate labels? (Select the most appropriate one based on the "Type of Improvement")
• Did you mark the proper milestone (Bug fix: 3.6.x, 5.x, or 6.x depending on impact, API modification or big change: 7.0)?
• Did you review?
• Did you check whether all relevant Contributor checkboxes have been checked?
• Did you do one of the following when ready to merge:
  • Squash: You/ the contributor Enable auto-merge (squash) and clean up the commit message.
  • Merge: Ensure that contributor has cleaned up their commit history, then merge with Create a merge commit.

[jackkoenig]

I'm actually surprised this works, since the full def flag below has default arguments for everything but name and help I would assume there's an ambiguity issue. Maybe it only materializes if you try to call this method?

I did test that by adding addOption(CliOption.flag("foo", "bar")) to trait EmitVcd, but that didn't trip it. So I guess we go with it? Another option is to make this package private so it only exists for binary compatibility reasons but you can't call it.

Anyway like I said, a little surprised this works, might dig a little bit more tomorrow to understand why.

[seldridge]

This generally looks good. I had something similar originally, but it wouldn't compile with Scala 3 (I think?). I had to back out the default options.

[jackkoenig]

This generally looks good. I had something similar originally, but it wouldn't compile with Scala 3 (I think?). I had to back out the default options.

I figured it out, whereas Scala 2 won't generate a copy method if you have any copy method, Scala 3 will still generate one unless the copy method has the exact arguments. So the solution is to implement a private version with the correct arguments.

I also made the constructor private to help reduce impact of adding any more arguments.

[seldridge]

Nice. Thanks for figuring this out, Jack.