Documentation for auto traits makes incorrect claims about Sync.

[alercah]

https://doc.rust-lang.org/nightly/reference/special-types-and-traits.html#auto-traits

This page claims that if T is Sync, then so is &mut T. This is false, however. I believe that it's false for RefUnwind as well.

[matthewjasper]

I think the documentation is correct: this compiles

pub fn use_sync<T: Sync>() {
    use_sync::<&mut T>();
}

[alercah]

Err, right. The issue still exists with RefUnwind, however.

[alercah]

Additionally, &T is not necessarily Send if T is Send; &T is Send if and only if T is Sync.