Derive Macro Subdiagnostic

#[derive(Subdiagnostic)]
{
    // Attributes available to this derive:
    #[label]
    #[help]
    #[help_once]
    #[note]
    #[note_once]
    #[warning]
    #[subdiagnostic]
    #[suggestion]
    #[suggestion_short]
    #[suggestion_hidden]
    #[suggestion_verbose]
    #[multipart_suggestion]
    #[multipart_suggestion_short]
    #[multipart_suggestion_hidden]
    #[multipart_suggestion_verbose]
    #[skip_arg]
    #[primary_span]
    #[suggestion_part]
    #[applicability]
}