Disambiguate calls to NetworkBehaviour::inject_event (#1543)

* Disambiguate calls to NetworkBehaviour::inject_event

There is a gnarly edge-case with the custom-derive where rustc
cannot disambiguate the call if:

- The NetworkBehaviourEventProcess trait is imported
- We nest NetworkBehaviours that use the custom-derive

* Update misc/core-derive/src/lib.rs

Co-Authored-By: Pierre Krieger <pierre.krieger1708@gmail.com>

* Fix build and add CHANGELOG

Co-authored-by: Pierre Krieger <pierre.krieger1708@gmail.com>

CHANGELOG.md

@@ -1,5 +1,8 @@
 # Version ???
 
+- `libp2p-core-derive`: Disambiguate calls to `NetworkBehaviour::inject_event`.
+  [PR 1543](https://github.com/libp2p/rust-libp2p/pull/1543)
+
 - `libp2p-floodsub`: Allow sent messages seen as subscribed.
   [PR 1520](https://github.com/libp2p/rust-libp2p/pull/1520)
 

misc/core-derive/src/lib.rs

@@ -293,8 +293,8 @@ fn build_struct(ast: &DeriveInput, data_struct: &DataStruct) -> TokenStream {
         }
 
         Some(match field.ident {
-            Some(ref i) => quote!{ #elem => self.#i.inject_event(peer_id, connection_id, ev) },
-            None => quote!{ #elem => self.#field_n.inject_event(peer_id, connection_id, ev) },
+            Some(ref i) => quote!{ #elem => #trait_to_impl::inject_event(&mut self.#i, peer_id, connection_id, ev) },
+            None => quote!{ #elem => #trait_to_impl::inject_event(&mut self.#field_n, peer_id, connection_id, ev) },
         })
     });
 

misc/core-derive/tests/test.rs

@@ -204,3 +204,35 @@ fn where_clause() {
         bar: T,
     }
 }
+
+#[test]
+fn nested_derives_with_import() {
+    use libp2p::swarm::NetworkBehaviourEventProcess;
+
+    #[allow(dead_code)]
+    #[derive(NetworkBehaviour)]
+    struct Foo {
+        ping: libp2p::ping::Ping,
+    }
+
+    #[allow(dead_code)]
+    #[derive(NetworkBehaviour)]
+    struct Bar {
+        foo: Foo,
+    }
+
+    impl NetworkBehaviourEventProcess<libp2p::ping::PingEvent> for Foo {
+        fn inject_event(&mut self, _: libp2p::ping::PingEvent) {
+        }
+    }
+
+    impl NetworkBehaviourEventProcess<()> for Bar {
+        fn inject_event(&mut self, _: ()) {
+        }
+    }
+
+    #[allow(dead_code)]
+    fn bar() {
+        require_net_behaviour::<Bar>();
+    }
+}