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/xcm/xcm-builder/src/lib.rs

@@ -50,8 +50,9 @@ pub use asset_conversion::{ConvertedAbstractAssetId, ConvertedConcreteAssetId};
 mod barriers;
 pub use barriers::{
 	AllowExplicitUnpaidExecutionFrom, AllowKnownQueryResponses, AllowSubscriptionsFrom,
-	AllowTopLevelPaidExecutionFrom, AllowUnpaidExecutionFrom, IsChildSystemParachain,
-	RespectSuspension, TakeWeightCredit, WithComputedOrigin,
+	AllowTopLevelPaidExecutionFrom, AllowUnpaidExecutionFrom, DenyReserveTransferToRelayChain,
+	DenyThenTry, IsChildSystemParachain, RespectSuspension, TakeWeightCredit, TrailingSetTopicAsId,
+	WithComputedOrigin,
 };
 
 mod process_xcm_message;
@@ -85,6 +86,9 @@ pub use matcher::{CreateMatcher, MatchXcm, Matcher};
 mod filter_asset_location;
 pub use filter_asset_location::{Case, NativeAsset};
 
+mod routing;
+pub use routing::{WithTopicSource, WithUniqueTopic};
+
 mod universal_exports;
 pub use universal_exports::{
 	ensure_is_remote, BridgeBlobDispatcher, BridgeMessage, DispatchBlob, DispatchBlobError,