Function cargo::util::toml::deprecated_underscore

fn deprecated_underscore<T>(
    old: &Option<T>,
    new: &Option<T>,
    new_path: &str,
    name: &str,
    kind: &str,
    edition: Edition,
    warnings: &mut Vec<String>,
) -> CargoResult<()>

Warn about paths that have been deprecated and may conflict.