diff --git a/concurrency.md b/concurrency.md index a382e4edf54..fc04bd83811 100644 --- a/concurrency.md +++ b/concurrency.md @@ -97,6 +97,7 @@ Almost all primitives are Send and Sync, and as a consequence pretty much all types you'll ever interact with are Send and Sync. Major exceptions include: + * raw pointers are neither Send nor Sync (because they have no safety guards) * `UnsafeCell` isn't Sync (and therefore `Cell` and `RefCell` aren't) * `Rc` isn't Send or Sync (because the refcount is shared and unsynchronized)