Why is PhantomData<T> only Send/Sync when T is Send/Sync?
Isn't it just a zero-size marker? If it's zero-size then surely it can be safely sent/shared across threads regardless of what T is... because there is nothing to be sent/shared?
Isn't it just a zero-size marker? If it's zero-size then surely it can be safely sent/shared across threads regardless of what T is... because there is nothing to be sent/shared?