The crate I'm currently working on has code like the following:

#[derive(Debug, Clone, Error)]
pub struct Error {
    pub(crate) kind: ErrorKind,
    backtrack: Option<ExtBacktrace>,
}

#[derive(Debug, Error)]
pub enum ErrorKind {
    // error variants go here
}

If I understand correctly, this doesn't currently allow the Error impl for Error to return types from the ErrorKind variants, which seems like it would be useful. I thought I might try #[error(transparent)] on Error's kind field, but that's not allowed. Is there currently a way to support this scenario? From the description of error(transparent) it seems like it would be a good fit for this, but maybe there's a good reason not to allow this.