XCM: Tools for uniquely referencing messages (#7234)

* Tools for unique topic references

* Formatting

* Naming

* Repot into routing.rs.

* More things done

* Universal Exporter supports topic-as-reference

* Some tests for the topic routing

* More tests

* Paid bridge tests

* Add message ID to sending events

* Formatting

* fix and integrate into test nets

* Move DenyThenTry and friend from Cumulus

* Append SetTopic rather than prepend

* Docs

* Docs

* Work with new ProcessMessage ID API

* Formatting

* Fix build

* Fixes

* Formatting

* Update xcm/xcm-builder/src/barriers.rs

Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com>

* Update xcm/xcm-builder/src/routing.rs

Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com>

* Docs

* Rename message_hash

* Formatting

* ".git/.scripts/commands/fmt/fmt.sh"

* Rename

* Another Rename

* ".git/.scripts/commands/fmt/fmt.sh"

* ".git/.scripts/commands/fmt/fmt.sh"

* Update xcm/xcm-builder/src/routing.rs

Co-authored-by: Keith Yeung <kungfukeith11@gmail.com>

---------

Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com>
Co-authored-by: command-bot <>
Co-authored-by: Keith Yeung <kungfukeith11@gmail.com>

polkadot/runtime/rococo/src/xcm_config.rs

@@ -40,7 +40,8 @@ use xcm_builder::{
 	ChildParachainAsNative, ChildParachainConvertsVia, ChildSystemParachainAsSuperuser,
 	CurrencyAdapter as XcmCurrencyAdapter, FixedWeightBounds, IsChildSystemParachain, IsConcrete,
 	MintLocation, SignedAccountId32AsNative, SignedToAccountId32, SovereignSignedViaLocation,
-	TakeWeightCredit, UsingComponents, WeightInfoBounds, WithComputedOrigin,
+	TakeWeightCredit, TrailingSetTopicAsId, UsingComponents, WeightInfoBounds, WithComputedOrigin,
+	WithUniqueTopic,
 };
 use xcm_executor::{traits::WithOriginFilter, XcmExecutor};
 
@@ -95,14 +96,14 @@ parameter_types! {
 
 /// The XCM router. When we want to send an XCM message, we use this type. It amalgamates all of our
 /// individual routers.
-pub type XcmRouter = (
+pub type XcmRouter = WithUniqueTopic<(
 	// Only one router so far - use DMP to communicate with child parachains.
 	ChildParachainRouter<
 		Runtime,
 		XcmPallet,
 		ExponentialPrice<FeeAssetId, BaseDeliveryFee, TransactionByteFee, Dmp>,
 	>,
-);
+)>;
 
 parameter_types! {
 	pub const Roc: MultiAssetFilter = Wild(AllOf { fun: WildFungible, id: Concrete(TokenLocation::get()) });
@@ -137,7 +138,7 @@ match_types! {
 }
 
 /// The barriers one of which must be passed for an XCM message to be executed.
-pub type Barrier = (
+pub type Barrier = TrailingSetTopicAsId<(
 	// Weight that is paid for may be consumed.
 	TakeWeightCredit,
 	// Expected responses are OK.
@@ -154,7 +155,7 @@ pub type Barrier = (
 		UniversalLocation,
 		ConstU32<8>,
 	>,
-);
+)>;
 
 /// A call filter for the XCM Transact instruction. This is a temporary measure until we
 /// properly account for proof size weights.