Required in derive but not in builder

[epage]

After #4090, one of our top-support issues for the derive API is when a field is conditionally required through conflicts but the derive still requires the field to be present Option / default_value are missing

Examples

• An exclusive flag and required arguments? #4732
• Does derived #[arg()] require arguments by default? [Beginner] #4675 (only sort-of related)
• Default Subcommand fails with required options #4755

Most other cases I think have been on Discord.

How we can better help people through this?

[jaskij]

My story is that, having used Clap since structopt was a separate crate, for cases like this I simply do not go to the derive documentation at all - it has been lacking in the past - and just check what methods are available directly in the documentation for Arg. A short mention that the behavior is different for derive, with a link to the actual documentation, would have been enough to avoid my problem.