From fe4846f54838c23de9fadf6ac92b0739e82c25b1 Mon Sep 17 00:00:00 2001
From: Ron <yrong1997@gmail.com>
Date: Wed, 11 Dec 2024 00:17:15 +0800
Subject: [PATCH] XCMv5: Fix for compatibility with V4 (#6503)

## Description

Our smoke tests transfer `WETH` from Sepolia to Westend-AssetHub breaks,
try to reregister `WETH` on AH but fails as following:


https://bridgehub-westend.subscan.io/xcm_message/westend-4796d6b3600aca32ef63b9953acf6a456cfd2fbe

https://assethub-westend.subscan.io/extrinsic/9731267-0?event=9731267-2

The reason is that the transact call encoded on BH to register the asset

https://github.com/paritytech/polkadot-sdk/blob/a77940bac783108fcae783c553528c8d5328e5b2/bridges/snowbridge/primitives/router/src/inbound/mod.rs#L282-L289
```
0x3500020209079edaa8020300fff9976782d46cc05630d1f6ebab18b2324d6b1400ce796ae65569a670d0c1cc1ac12515a3ce21b5fbf729d63d7b289baad070139d01000000000000000000000000000000
```

the `asset_id` which is the xcm location can't be decoded on AH in V5

Issue initial post in
https://matrix.to/#/!qUtSTcfMJzBdPmpFKa:parity.io/$RNMAxIIOKGtBAqkgwiFuQf4eNaYpmOK-Pfw4d6vv1aU?via=parity.io&via=matrix.org&via=web3.foundation

---------

Co-authored-by: Adrian Catangiu <adrian@parity.io>
Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com>
---
 .../pallets/inbound-queue/src/mock.rs         | 14 -----------
 .../pallets/inbound-queue/src/test.rs         | 23 +++++++++----------
 polkadot/xcm/src/v5/junction.rs               |  4 ++++
 prdoc/pr_6503.prdoc                           | 10 ++++++++
 4 files changed, 25 insertions(+), 26 deletions(-)
 create mode 100644 prdoc/pr_6503.prdoc

diff --git a/bridges/snowbridge/pallets/inbound-queue/src/mock.rs b/bridges/snowbridge/pallets/inbound-queue/src/mock.rs
index 675d4b691593..eed0656e9ca7 100644
--- a/bridges/snowbridge/pallets/inbound-queue/src/mock.rs
+++ b/bridges/snowbridge/pallets/inbound-queue/src/mock.rs
@@ -248,20 +248,6 @@ impl inbound_queue::Config for Test {
 	type AssetTransactor = SuccessfulTransactor;
 }
 
-pub fn last_events(n: usize) -> Vec<RuntimeEvent> {
-	frame_system::Pallet::<Test>::events()
-		.into_iter()
-		.rev()
-		.take(n)
-		.rev()
-		.map(|e| e.event)
-		.collect()
-}
-
-pub fn expect_events(e: Vec<RuntimeEvent>) {
-	assert_eq!(last_events(e.len()), e);
-}
-
 pub fn setup() {
 	System::set_block_number(1);
 	Balances::mint_into(
diff --git a/bridges/snowbridge/pallets/inbound-queue/src/test.rs b/bridges/snowbridge/pallets/inbound-queue/src/test.rs
index 053a341b54a0..aa99d63b4bf9 100644
--- a/bridges/snowbridge/pallets/inbound-queue/src/test.rs
+++ b/bridges/snowbridge/pallets/inbound-queue/src/test.rs
@@ -9,7 +9,7 @@ use sp_keyring::Sr25519Keyring as Keyring;
 use sp_runtime::DispatchError;
 use sp_std::convert::From;
 
-use crate::{Error, Event as InboundQueueEvent};
+use crate::Error;
 
 use crate::mock::*;
 
@@ -35,17 +35,16 @@ fn test_submit_happy_path() {
 		assert_eq!(Balances::balance(&channel_sovereign), initial_fund);
 
 		assert_ok!(InboundQueue::submit(origin.clone(), message.clone()));
-		expect_events(vec![InboundQueueEvent::MessageReceived {
-			channel_id: hex!("c173fac324158e77fb5840738a1a541f633cbec8884c6a601c567d2b376a0539")
-				.into(),
-			nonce: 1,
-			message_id: [
-				118, 166, 139, 182, 84, 52, 165, 189, 54, 14, 178, 73, 2, 228, 192, 97, 153, 201,
-				4, 75, 151, 15, 82, 6, 164, 187, 162, 133, 26, 183, 186, 126,
-			],
-			fee_burned: 110000000000,
-		}
-		.into()]);
+
+		let events = frame_system::Pallet::<Test>::events();
+		assert!(
+			events.iter().any(|event| matches!(
+				event.event,
+				RuntimeEvent::InboundQueue(Event::MessageReceived { nonce, ..})
+					if nonce == 1
+			)),
+			"no event emit."
+		);
 
 		let delivery_cost = InboundQueue::calculate_delivery_cost(message.encode().len() as u32);
 		assert!(
diff --git a/polkadot/xcm/src/v5/junction.rs b/polkadot/xcm/src/v5/junction.rs
index 952b61cd9ffe..d86a762fcf44 100644
--- a/polkadot/xcm/src/v5/junction.rs
+++ b/polkadot/xcm/src/v5/junction.rs
@@ -143,16 +143,20 @@ pub enum NetworkId {
 	/// The Kusama canary-net Relay-chain.
 	Kusama,
 	/// An Ethereum network specified by its chain ID.
+	#[codec(index = 7)]
 	Ethereum {
 		/// The EIP-155 chain ID.
 		#[codec(compact)]
 		chain_id: u64,
 	},
 	/// The Bitcoin network, including hard-forks supported by Bitcoin Core development team.
+	#[codec(index = 8)]
 	BitcoinCore,
 	/// The Bitcoin network, including hard-forks supported by Bitcoin Cash developers.
+	#[codec(index = 9)]
 	BitcoinCash,
 	/// The Polkadot Bulletin chain.
+	#[codec(index = 10)]
 	PolkadotBulletin,
 }
 
diff --git a/prdoc/pr_6503.prdoc b/prdoc/pr_6503.prdoc
new file mode 100644
index 000000000000..dc296a93f0eb
--- /dev/null
+++ b/prdoc/pr_6503.prdoc
@@ -0,0 +1,10 @@
+title: "xcm: minor fix for compatibility with V4"
+
+doc:
+  - audience: ["Runtime Dev", "Runtime User"]
+    description: |
+      Following the removal of `Rococo`, `Westend` and `Wococo` from `NetworkId`, fixed `xcm::v5::NetworkId` encoding/decoding to be compatible with `xcm::v4::NetworkId`
+
+crates:
+- name: staging-xcm
+  bump: patch