Document derive support in shared types page of website
diff --git a/book/src/shared.md b/book/src/shared.md
index 09465fe..b919cde 100644
--- a/book/src/shared.md
+++ b/book/src/shared.md
@@ -179,3 +179,47 @@
Extern enums support all the same features as ordinary shared enums (explicit
discriminants, repr). Again, CXX will static assert that all of those things you
wrote are correct.
+
+## Derives
+
+The following standard traits are supported in `derive(...)` within the CXX
+bridge module.
+
+- `Clone`
+- `Copy`
+- `Debug`
+- `Default`
+- `Eq`
+- `Hash`
+- `Ord`
+- `PartialEq`
+- `PartialOrd`
+
+Note that shared enums automatically always come with impls of `Copy`, `Clone`,
+`Eq`, and `PartialEq`, so you're free to omit those derives on an enum.
+
+```rust,noplayground
+#[cxx::bridge]
+mod ffi {
+ #[derive(Clone, Debug, Hash)]
+ struct ExampleStruct {
+ x: u32,
+ s: String,
+ }
+
+ #[derive(Hash, Ord, PartialOrd)]
+ enum ExampleEnum {
+ Yes,
+ No,
+ }
+}
+```
+
+The derives naturally apply to *both* the Rust data type *and* the corresponding
+C++ data type:
+
+- `Hash` gives you a specialization of [`template <> struct std::hash<T>`][hash] in C++
+- `PartialEq` produces `operator==` and `operator!=`
+- `PartialOrd` produces `operator<`, `operator<=`, `operator>`, `operator>=`
+
+[hash]: https://en.cppreference.com/w/cpp/utility/hash
