protocols/gossipsub: Allow publishing to anything that implements Into<TopicHash> (#2862)

protocols/gossipsub/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 - Update to `libp2p-swarm` `v0.39.0`.
 
+- Allow publishing with any `impl Into<TopicHash>` as a topic. See [PR 2862].
+
+[PR 2862]: https://github.com/libp2p/rust-libp2p/pull/2862
+
 # 0.40.0
 
 - Update prost requirement from 0.10 to 0.11 which no longer installs the protoc Protobuf compiler.

protocols/gossipsub/src/behaviour.rs

@@ -587,19 +587,20 @@ where
     }
 
     /// Publishes a message with multiple topics to the network.
-    pub fn publish<H: Hasher>(
+    pub fn publish(
         &mut self,
-        topic: Topic<H>,
+        topic: impl Into<TopicHash>,
         data: impl Into<Vec<u8>>,
     ) -> Result<MessageId, PublishError> {
         let data = data.into();
+        let topic = topic.into();
 
         // Transform the data before building a raw_message.
         let transformed_data = self
             .data_transform
-            .outbound_transform(&topic.hash(), data.clone())?;
+            .outbound_transform(&topic, data.clone())?;
 
-        let raw_message = self.build_raw_message(topic.into(), transformed_data)?;
+        let raw_message = self.build_raw_message(topic, transformed_data)?;
 
         // calculate the message id from the un-transformed data
         let msg_id = self.config.message_id(&GossipsubMessage {