Sure, it seems like arguments are checked against prefix_pattern to determine whether they're an option, and only after that succeeds are they additionally checked against long_prefix_pattern. I was hoping the two patterns would be checked separately so I could get mutually exclusive short/long option prefixes.

In essence, I just want to disallow the use of --c in this example. This may not be possible without some unholy hacks, but I'm open to experimenting!