add custom derives callback

This callback allows us to specify arbitrary derive attributes for each
named struct. This is useful for adding things that can't easily be
implemented separately, such as `serde::Deserialize` or
`zerocopy::FromBytes`.

1 files changed, 8 insertions, 0 deletions

diff --git a/src/callbacks.rs b/src/callbacks.rs
index e288af43..9b345449 100644
--- a/src/callbacks.rs
+++ b/src/callbacks.rs
@@ -95,4 +95,12 @@ pub trait ParseCallbacks: fmt::Debug + UnwindSafe {
     ) -> Option<ImplementsTrait> {
         None
     }
+
+    /// Provide a list of custom derive attributes.
+    ///
+    /// If no additional attributes are wanted, this function should return an
+    /// empty `Vec`.
+    fn add_derives(&self, _name: &str) -> Vec<String> {
+        vec![]
+    }
 }