phantom-data: Add Send and Sync columns

Author: Enselic

src/phantom-data.md

@@ -234,14 +234,14 @@ standard library made a utility for itself called `Unique<T>` which:
 
 Here’s a table of all the wonderful ways `PhantomData` could be used:
 
-| Phantom type                | `'a`      | `T`                       |
-|-----------------------------|-----------|---------------------------|
-| `PhantomData<T>`            | -         | covariant (with drop check) |
-| `PhantomData<&'a T>`        | covariant | covariant                 |
-| `PhantomData<&'a mut T>`    | covariant | invariant                 |
-| `PhantomData<*const T>`     | -         | covariant                 |
-| `PhantomData<*mut T>`       | -         | invariant                 |
-| `PhantomData<fn(T)>`        | -         | contravariant             |
-| `PhantomData<fn() -> T>`    | -         | covariant                 |
-| `PhantomData<fn(T) -> T>`   | -         | invariant                 |
-| `PhantomData<Cell<&'a ()>>` | invariant | -                         |
+| Phantom type                | `'a`      | `T`                         | `Send`    | `Sync`    |
+|-----------------------------|-----------|-----------------------------|-----------|-----------|
+| `PhantomData<T>`            | -         | covariant (with drop check) | `T: Send` | `T: Sync` |
+| `PhantomData<&'a T>`        | covariant | covariant                   | `T: Sync` | `T: Sync` |
+| `PhantomData<&'a mut T>`    | covariant | invariant                   | `T: Send` | `T: Sync` |
+| `PhantomData<*const T>`     | -         | covariant                   | -         | -         |
+| `PhantomData<*mut T>`       | -         | invariant                   | -         | -         |
+| `PhantomData<fn(T)>`        | -         | contravariant               | `Send`    | `Sync`    |
+| `PhantomData<fn() -> T>`    | -         | covariant                   | `Send`    | `Sync`    |
+| `PhantomData<fn(T) -> T>`   | -         | invariant                   | `Send`    | `Sync`    |
+| `PhantomData<Cell<&'a ()>>` | invariant | -                           | `Send`    | -         |