Nonallocating ConnectionEnd::versions method (#1889)

* Make `ConnectionEnd::versions` non-allocating.

* Elide lifetimes

* Add changelog entry.

.changelog/unreleased/improvements/ibc-relayer/1880-nonallocating-verions-method.md

@@ -0,0 +1 @@
+- Changed `ConnectionEnd::versions` method to be non-allocating by having it return a `&[Version]` instead of `Vec<Version>`. ([#1880](https://github.com/informalsystems/ibc-rs/pull/1880))

modules/src/core/ics03_connection/connection.rs

@@ -217,8 +217,8 @@ impl ConnectionEnd {
     }
 
     /// Getter for the list of versions in this connection end.
-    pub fn versions(&self) -> Vec<Version> {
-        self.versions.clone()
+    pub fn versions(&self) -> &[Version] {
+        &self.versions
     }
 
     /// Getter for the counterparty.

modules/src/core/ics03_connection/handler/conn_open_confirm.rs

@@ -35,7 +35,7 @@ pub(crate) fn process(
             Some(msg.connection_id.clone()), // Local connection id.
             ctx.commitment_prefix(),      // Local commitment prefix.
         ),
-        conn_end.versions(),
+        conn_end.versions().to_vec(),
         conn_end.delay_period(),
     );
 

modules/src/core/ics04_channel/handler/chan_open_init.rs

@@ -30,7 +30,7 @@ pub(crate) fn process(
     // An IBC connection running on the local (host) chain should exist.
     let conn = ctx.connection_end(&msg.channel.connection_hops()[0])?;
     let get_versions = conn.versions();
-    let version = match get_versions.as_slice() {
+    let version = match get_versions {
         [version] => version,
         _ => return Err(Error::invalid_version_length_connection()),
     };

modules/src/core/ics04_channel/handler/chan_open_try.rs

@@ -77,7 +77,7 @@ pub(crate) fn process(
     }
 
     let get_versions = conn.versions();
-    let version = match get_versions.as_slice() {
+    let version = match get_versions {
         [version] => version,
         _ => return Err(Error::invalid_version_length_connection()),
     };

relayer/src/connection.rs

@@ -891,7 +891,7 @@ impl<ChainA: ChainHandle, ChainB: ChainHandle> Connection<ChainA, ChainB> {
                 .query_compatible_versions()
                 .map_err(|e| ConnectionError::chain_query(self.src_chain().id(), e))?
         } else {
-            src_connection.versions()
+            src_connection.versions().to_vec()
         };
 
         // Get signer