Sync only type makes no sense without Send in rust: You need to move objects across thread boundaries to make it sharable. Is this correct?

[quinedot]

Recommending this post again:

Example of a type that is not `Send`?

For completeness's sake, I think it may be interesting to know of types which are Sync (safe to share across threads) but which are nevertheless not Send (safe to own across threads): Rc is neither, so the difference is harder to grasp. Some reminders By sharing I mean &-access, be it directly –&T references–, or indirectly (capable of ultimatetly yielding & access): Arc<T>, &Arc<T>, &&T, &&mut T, etc. The main cause of "unsafety to share across threads", or, more generally, the main reaso…