fn check_rust_version_for_optional_dependency(
rust_version: Option<&RustVersion>,
) -> CargoResult<bool>Expand description
When the --optional option is added using cargo add, we need to
check the current rust-version. As the dep: syntax is only available
starting with Rust 1.60.0
true means that the rust-version is None or the rust-version is higher
than the version needed.
Note: Previous versions can only use the implicit feature name.