Polkadot parachains get topic-based message IDs (#2642)

* Polkadot parachains get topics

* Formatting

---------

Co-authored-by: joepetrowski <joe@parity.io>
Co-authored-by: parity-processbot <>

cumulus/parachains/runtimes/testing/rococo-parachain/src/lib.rs

@@ -70,7 +70,7 @@ use parachains_common::{
 };
 use xcm_builder::{
 	AllowKnownQueryResponses, AllowSubscriptionsFrom, AsPrefixedGeneralIndex, ConvertedConcreteId,
-	FungiblesAdapter, LocalMint,
+	FungiblesAdapter, LocalMint, TrailingSetTopicAsId, WithUniqueTopic,
 };
 use xcm_executor::traits::JustTry;
 
@@ -383,7 +383,7 @@ match_types! {
 	};
 }
 
-pub type Barrier = (
+pub type Barrier = TrailingSetTopicAsId<(
 	TakeWeightCredit,
 	AllowTopLevelPaidExecutionFrom<Everything>,
 	// Parent & its unit plurality gets free execution.
@@ -394,7 +394,7 @@ pub type Barrier = (
 	AllowKnownQueryResponses<PolkadotXcm>,
 	// Subscriptions for version tracking are OK.
 	AllowSubscriptionsFrom<Everything>,
-);
+)>;
 
 parameter_types! {
 	pub MaxAssetsIntoHolding: u32 = 64;
@@ -441,12 +441,12 @@ pub type LocalOriginToLocation = SignedToAccountId32<RuntimeOrigin, AccountId, R
 
 /// The means for routing XCM messages which are not for local execution into the right message
 /// queues.
-pub type XcmRouter = (
+pub type XcmRouter = WithUniqueTopic<(
 	// Two routers - use UMP to communicate with the relay chain:
 	cumulus_primitives_utility::ParentAsUmp<ParachainSystem, (), ()>,
 	// ..and XCMP to communicate with the sibling chains.
 	XcmpQueue,
-);
+)>;
 
 #[cfg(feature = "runtime-benchmarks")]
 parameter_types! {