fix(xcm): use single encoding for XCM messages (#2278)

* fix(xcm): use single encoding for XCM messages

* update changelog

---------

Co-authored-by: Michael Mueller <mich@elmueller.net>

Author: peterwht

CHANGELOG.md

@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Changed
 - [E2E] Update `subxt` and `polkadot-sdk` dependencies ‒ [#2174](https://github.com/use-ink/ink/pull/2174)
 - Update repository URLs & references from `paritytech` GitHub organization to new `use-ink` one ‒ [#2220](https://github.com/use-ink/ink/pull/2220) and [#2248](https://github.com/use-ink/ink/pull/2248)
+- Fix XCM-support to single encode the XCM message [#2278](https://github.com/use-ink/ink/pull/2278)
 
 ### Fixed
 - Fix outdated docs for `[ink_e2e::test]` ‒ [#2162](https://github.com/use-ink/ink/pull/2162)

crates/env/src/engine/on_chain/impls.rs

@@ -735,8 +735,8 @@ impl TypedEnvBackend for EnvInstance {
     {
         let mut scope = self.scoped_buffer();
 
-        // Double encoding the message as the host fn expects an encoded message.
-        let enc_msg = scope.take_encoded(&scale::Encode::encode(msg));
+        let enc_msg = scope.take_encoded(msg);
+
         #[allow(deprecated)]
         ext::xcm_execute(enc_msg).map_err(Into::into)
     }
@@ -755,8 +755,7 @@ impl TypedEnvBackend for EnvInstance {
         scope.append_encoded(dest);
         let enc_dest = scope.take_appended();
 
-        // Double encoding the message as the host fn expects an encoded message.
-        scope.append_encoded(&scale::Encode::encode(msg));
+        scope.append_encoded(msg);
         let enc_msg = scope.take_appended();
         #[allow(deprecated)]
         ext::xcm_send(enc_dest, enc_msg, output.try_into().unwrap())?;