[rust]Test compiled successfully, but it's marked `compile_fail`

Exercism Bugs & Feature Requests
1

exercise: doubly-linked-list

#[allow(unused)]
#[cfg(feature = "advanced")]
/// ```compile_fail
/// use doubly_linked_list::LinkedList;
/// trait AssertSend: Send {}
/// impl<T> AssertSend for LinkedList<T> {}
/// ```
pub struct IllegalSend;

#[allow(unused)]
#[cfg(feature = "advanced")]
/// ```compile_fail
/// use doubly_linked_list::LinkedList;
/// trait AssertSync: Sync {}
/// impl<T> AssertSync for LinkedList<T> {}
/// ```
pub struct IllegalSync;

There are some code in doc within pre_implemented.rs, but marked compile_fail.
When advanced is open, it should be success otherwise tests can not be pass.
The diff between doc and test prevent me to commit code.

2

These tests are correct. If they fail, then your solution is wrong.

3

I passed the test, but these doc did not, either all pass or all fail.

fn advanced_linked_list_is_send_sync() {
    trait AssertSend: Send {}
    trait AssertSync: Sync {}

    impl<T: Send> AssertSend for LinkedList<T> {}
    impl<T: Sync> AssertSync for LinkedList<T> {}
}

fn code_in_doc() {
    use doubly_linked_list::LinkedList;
    trait AssertSync: Sync {}
    impl<T> AssertSync for LinkedList<T> {}
}

I think it should be #[cfg(not(feature = "advanced"))] with IllegalSync and IllegalSend, the goal of advanced is make LinkedList<T> implement Send and Sync, in this time, compile should not fail.

4

You have implemented Send and Sync without a trait bound, which means your linked list could be used to send or share data types that are fundamentally not thread safe. You must add the trait bound : Send and : Sync respectively.