Direct XCM ExportMessage fees for different bridges to different receiver accounts (#2021)

cumulus/parachains/runtimes/assets/asset-hub-rococo/src/xcm_config.rs

@@ -53,7 +53,7 @@ use xcm_builder::{
 	SiblingParachainConvertsVia, SignedAccountId32AsNative, SignedToAccountId32,
 	SovereignSignedViaLocation, StartsWith, StartsWithExplicitGlobalConsensus, TakeWeightCredit,
 	TrailingSetTopicAsId, UsingComponents, WeightInfoBounds, WithComputedOrigin, WithUniqueTopic,
-	XcmFeesToAccount,
+	XcmFeeManagerFromComponents, XcmFeeToAccount,
 };
 use xcm_executor::{traits::WithOriginFilter, XcmExecutor};
 
@@ -75,7 +75,7 @@ parameter_types! {
 		PalletInstance(<PoolAssets as PalletInfoAccess>::index() as u8).into();
 	pub CheckingAccount: AccountId = PolkadotXcm::check_account();
 	pub const GovernanceLocation: MultiLocation = MultiLocation::parent();
-	pub TreasuryAccount: Option<AccountId> = Some(TREASURY_PALLET_ID.into_account_truncating());
+	pub TreasuryAccount: AccountId = TREASURY_PALLET_ID.into_account_truncating();
 	pub RelayTreasuryLocation: MultiLocation = (Parent, PalletInstance(rococo_runtime_constants::TREASURY_PALLET_ID)).into();
 }
 
@@ -619,7 +619,10 @@ impl xcm_executor::Config for XcmConfig {
 	type MaxAssetsIntoHolding = MaxAssetsIntoHolding;
 	type AssetLocker = ();
 	type AssetExchanger = ();
-	type FeeManager = XcmFeesToAccount<Self, WaivedLocations, AccountId, TreasuryAccount>;
+	type FeeManager = XcmFeeManagerFromComponents<
+		WaivedLocations,
+		XcmFeeToAccount<Self::AssetTransactor, AccountId, TreasuryAccount>,
+	>;
 	type MessageExporter = ();
 	type UniversalAliases =
 		(bridging::to_wococo::UniversalAliases, bridging::to_rococo::UniversalAliases);

cumulus/parachains/runtimes/assets/asset-hub-rococo/tests/tests.rs

@@ -683,7 +683,7 @@ mod asset_hub_rococo_tests {
 			bridging_to_asset_hub_wococo,
 			WeightLimit::Unlimited,
 			Some(xcm_config::bridging::XcmBridgeHubRouterFeeAssetId::get()),
-			Some(xcm_config::TreasuryAccount::get().unwrap()),
+			Some(xcm_config::TreasuryAccount::get()),
 		)
 	}
 
@@ -871,7 +871,7 @@ mod asset_hub_wococo_tests {
 			with_wococo_flavor_bridging_to_asset_hub_rococo,
 			WeightLimit::Unlimited,
 			Some(xcm_config::bridging::XcmBridgeHubRouterFeeAssetId::get()),
-			Some(xcm_config::TreasuryAccount::get().unwrap()),
+			Some(xcm_config::TreasuryAccount::get()),
 		)
 	}
 

cumulus/parachains/runtimes/assets/asset-hub-westend/src/xcm_config.rs

@@ -52,7 +52,7 @@ use xcm_builder::{
 	SiblingParachainConvertsVia, SignedAccountId32AsNative, SignedToAccountId32,
 	SovereignSignedViaLocation, StartsWith, StartsWithExplicitGlobalConsensus, TakeWeightCredit,
 	TrailingSetTopicAsId, UsingComponents, WeightInfoBounds, WithComputedOrigin, WithUniqueTopic,
-	XcmFeesToAccount,
+	XcmFeeManagerFromComponents, XcmFeeToAccount,
 };
 use xcm_executor::{traits::WithOriginFilter, XcmExecutor};
 
@@ -73,7 +73,7 @@ parameter_types! {
 	pub PoolAssetsPalletLocation: MultiLocation =
 		PalletInstance(<PoolAssets as PalletInfoAccess>::index() as u8).into();
 	pub CheckingAccount: AccountId = PolkadotXcm::check_account();
-	pub TreasuryAccount: Option<AccountId> = Some(TREASURY_PALLET_ID.into_account_truncating());
+	pub TreasuryAccount: AccountId = TREASURY_PALLET_ID.into_account_truncating();
 	pub RelayTreasuryLocation: MultiLocation = (Parent, PalletInstance(westend_runtime_constants::TREASURY_PALLET_ID)).into();
 }
 
@@ -562,7 +562,10 @@ impl xcm_executor::Config for XcmConfig {
 	type MaxAssetsIntoHolding = MaxAssetsIntoHolding;
 	type AssetLocker = ();
 	type AssetExchanger = ();
-	type FeeManager = XcmFeesToAccount<Self, WaivedLocations, AccountId, TreasuryAccount>;
+	type FeeManager = XcmFeeManagerFromComponents<
+		WaivedLocations,
+		XcmFeeToAccount<Self::AssetTransactor, AccountId, TreasuryAccount>,
+	>;
 	type MessageExporter = ();
 	type UniversalAliases = Nothing;
 	type CallDispatcher = WithOriginFilter<SafeCallFilter>;

cumulus/parachains/runtimes/bridge-hubs/bridge-hub-rococo/src/xcm_config.rs

@@ -24,9 +24,18 @@ use crate::{
 		BridgeGrandpaRococoInstance, BridgeGrandpaWococoInstance, DeliveryRewardInBalance,
 		RequiredStakeForStakeAndSlash,
 	},
-	bridge_hub_rococo_config::ToBridgeHubWococoHaulBlobExporter,
+	bridge_hub_rococo_config::{
-	bridge_hub_wococo_config::ToBridgeHubRococoHaulBlobExporter,
+		AssetHubRococoParaId, BridgeHubWococoChainId, BridgeHubWococoMessagesLane,
+		ToBridgeHubWococoHaulBlobExporter, WococoGlobalConsensusNetwork,
+	},
+	bridge_hub_wococo_config::{
+		AssetHubWococoParaId, BridgeHubRococoChainId, BridgeHubRococoMessagesLane,
+		RococoGlobalConsensusNetwork, ToBridgeHubRococoHaulBlobExporter,
+	},
 };
+use bp_messages::LaneId;
+use bp_relayers::{PayRewardFromAccount, RewardsAccountOwner, RewardsAccountParams};
+use bp_runtime::ChainId;
 use frame_support::{
 	match_types, parameter_types,
 	traits::{ConstU32, Contains, Equals, Everything, Nothing},
@@ -43,18 +52,20 @@ use polkadot_runtime_common::xcm_sender::ExponentialPrice;
 use rococo_runtime_constants::system_parachain;
 use sp_core::Get;
 use sp_runtime::traits::AccountIdConversion;
+use sp_std::marker::PhantomData;
 use xcm::latest::prelude::*;
 use xcm_builder::{
-	AccountId32Aliases, AllowExplicitUnpaidExecutionFrom, AllowKnownQueryResponses,
+	deposit_or_burn_fee, AccountId32Aliases, AllowExplicitUnpaidExecutionFrom,
-	AllowSubscriptionsFrom, AllowTopLevelPaidExecutionFrom, CurrencyAdapter,
+	AllowKnownQueryResponses, AllowSubscriptionsFrom, AllowTopLevelPaidExecutionFrom,
-	DenyReserveTransferToRelayChain, DenyThenTry, EnsureXcmOrigin, IsConcrete, ParentAsSuperuser,
+	CurrencyAdapter, DenyReserveTransferToRelayChain, DenyThenTry, EnsureXcmOrigin, HandleFee,
-	ParentIsPreset, RelayChainAsNative, SiblingParachainAsNative, SiblingParachainConvertsVia,
+	IsConcrete, ParentAsSuperuser, ParentIsPreset, RelayChainAsNative, SiblingParachainAsNative,
-	SignedAccountId32AsNative, SignedToAccountId32, SovereignSignedViaLocation, TakeWeightCredit,
+	SiblingParachainConvertsVia, SignedAccountId32AsNative, SignedToAccountId32,
-	TrailingSetTopicAsId, UsingComponents, WeightInfoBounds, WithComputedOrigin, WithUniqueTopic,
+	SovereignSignedViaLocation, TakeWeightCredit, TrailingSetTopicAsId, UsingComponents,
-	XcmFeesToAccount,
+	WeightInfoBounds, WithComputedOrigin, WithUniqueTopic, XcmFeeManagerFromComponents,
+	XcmFeeToAccount,
 };
 use xcm_executor::{
-	traits::{ExportXcm, WithOriginFilter},
+	traits::{ExportXcm, FeeReason, TransactAsset, WithOriginFilter},
 	XcmExecutor,
 };
 
@@ -66,7 +77,7 @@ parameter_types! {
 		X2(GlobalConsensus(RelayNetwork::get()), Parachain(ParachainInfo::parachain_id().into()));
 	pub const MaxInstructions: u32 = 100;
 	pub const MaxAssetsIntoHolding: u32 = 64;
-	pub TreasuryAccount: Option<AccountId> = Some(TREASURY_PALLET_ID.into_account_truncating());
+	pub TreasuryAccount: AccountId = TREASURY_PALLET_ID.into_account_truncating();
 	pub RelayTreasuryLocation: MultiLocation = (Parent, PalletInstance(rococo_runtime_constants::TREASURY_PALLET_ID)).into();
 }
 
@@ -290,7 +301,26 @@ impl xcm_executor::Config for XcmConfig {
 	type SubscriptionService = PolkadotXcm;
 	type PalletInstancesInfo = AllPalletsWithSystem;
 	type MaxAssetsIntoHolding = MaxAssetsIntoHolding;
-	type FeeManager = XcmFeesToAccount<Self, WaivedLocations, AccountId, TreasuryAccount>;
+	type FeeManager = XcmFeeManagerFromComponents<
+		WaivedLocations,
+		(
+			XcmExportFeeToRelayerRewardAccounts<
+				Self::AssetTransactor,
+				WococoGlobalConsensusNetwork,
+				AssetHubWococoParaId,
+				BridgeHubWococoChainId,
+				BridgeHubWococoMessagesLane,
+			>,
+			XcmExportFeeToRelayerRewardAccounts<
+				Self::AssetTransactor,
+				RococoGlobalConsensusNetwork,
+				AssetHubRococoParaId,
+				BridgeHubRococoChainId,
+				BridgeHubRococoMessagesLane,
+			>,
+			XcmFeeToAccount<Self::AssetTransactor, AccountId, TreasuryAccount>,
+		),
+	>;
 	type MessageExporter = BridgeHubRococoOrBridgeHubWococoSwitchExporter;
 	type UniversalAliases = Nothing;
 	type CallDispatcher = WithOriginFilter<SafeCallFilter>;
@@ -401,3 +431,96 @@ impl ExportXcm for BridgeHubRococoOrBridgeHubWococoSwitchExporter {
 		}
 	}
 }
+
+/// A `HandleFee` implementation that simply deposits the fees for `ExportMessage` XCM instructions
+/// into the accounts that are used for paying the relayer rewards.
+/// Burns the fees in case of a failure.
+pub struct XcmExportFeeToRelayerRewardAccounts<
+	AssetTransactor,
+	DestNetwork,
+	DestParaId,
+	DestBridgeHubId,
+	BridgeLaneId,
+>(PhantomData<(AssetTransactor, DestNetwork, DestParaId, DestBridgeHubId, BridgeLaneId)>);
+
+impl<
+		AssetTransactor: TransactAsset,
+		DestNetwork: Get<NetworkId>,
+		DestParaId: Get<cumulus_primitives_core::ParaId>,
+		DestBridgeHubId: Get<ChainId>,
+		BridgeLaneId: Get<LaneId>,
+	> HandleFee
+	for XcmExportFeeToRelayerRewardAccounts<
+		AssetTransactor,
+		DestNetwork,
+		DestParaId,
+		DestBridgeHubId,
+		BridgeLaneId,
+	>
+{
+	fn handle_fee(
+		fee: MultiAssets,
+		maybe_context: Option<&XcmContext>,
+		reason: FeeReason,
+	) -> MultiAssets {
+		if matches!(reason, FeeReason::Export { network: bridged_network, destination }
+				if bridged_network == DestNetwork::get() &&
+					destination == X1(Parachain(DestParaId::get().into())))
+		{
+			// We have 2 relayer rewards accounts:
+			// - the SA of the source parachain on this BH: this pays the relayers for delivering
+			//   Source para -> Target Para message delivery confirmations
+			// - the SA of the destination parachain on this BH: this pays the relayers for
+			//   delivering Target para -> Source Para messages
+			// We split the `ExportMessage` fee between these 2 accounts.
+			let source_para_account = PayRewardFromAccount::<
+				pallet_balances::Pallet<Runtime>,
+				AccountId,
+			>::rewards_account(RewardsAccountParams::new(
+				BridgeLaneId::get(),
+				DestBridgeHubId::get(),
+				RewardsAccountOwner::ThisChain,
+			));
+
+			let dest_para_account = PayRewardFromAccount::<
+				pallet_balances::Pallet<Runtime>,
+				AccountId,
+			>::rewards_account(RewardsAccountParams::new(
+				BridgeLaneId::get(),
+				DestBridgeHubId::get(),
+				RewardsAccountOwner::BridgedChain,
+			));
+
+			for asset in fee.into_inner() {
+				match asset.fun {
+					Fungible(total_fee) => {
+						let source_fee = total_fee / 2;
+						deposit_or_burn_fee::<AssetTransactor, _>(
+							MultiAsset { id: asset.id, fun: Fungible(source_fee) }.into(),
+							maybe_context,
+							source_para_account.clone(),
+						);
+
+						let dest_fee = total_fee - source_fee;
+						deposit_or_burn_fee::<AssetTransactor, _>(
+							MultiAsset { id: asset.id, fun: Fungible(dest_fee) }.into(),
+							maybe_context,
+							dest_para_account.clone(),
+						);
+					},
+					NonFungible(_) => {
+						deposit_or_burn_fee::<AssetTransactor, _>(
+							asset.into(),
+							maybe_context,
+							source_para_account.clone(),
+						);
+					},
+				}
+			}
+
+			return MultiAssets::new()
+		}
+
+		fee
+	}
+}

cumulus/parachains/runtimes/contracts/contracts-rococo/src/xcm_config.rs

@@ -41,7 +41,7 @@ use xcm_builder::{
 	NativeAsset, ParentAsSuperuser, ParentIsPreset, RelayChainAsNative, SiblingParachainAsNative,
 	SiblingParachainConvertsVia, SignedAccountId32AsNative, SignedToAccountId32,
 	SovereignSignedViaLocation, TakeWeightCredit, TrailingSetTopicAsId, UsingComponents,
-	WithComputedOrigin, WithUniqueTopic, XcmFeesToAccount,
+	WithComputedOrigin, WithUniqueTopic, XcmFeeManagerFromComponents, XcmFeeToAccount,
 };
 use xcm_executor::XcmExecutor;
 
@@ -51,7 +51,7 @@ parameter_types! {
 	pub RelayChainOrigin: RuntimeOrigin = cumulus_pallet_xcm::Origin::Relay.into();
 	pub UniversalLocation: InteriorMultiLocation = Parachain(ParachainInfo::parachain_id().into()).into();
 	pub const ExecutiveBody: BodyId = BodyId::Executive;
-	pub TreasuryAccount: Option<AccountId> = Some(TREASURY_PALLET_ID.into_account_truncating());
+	pub TreasuryAccount: AccountId = TREASURY_PALLET_ID.into_account_truncating();
 	pub RelayTreasuryLocation: MultiLocation = (Parent, PalletInstance(rococo_runtime_constants::TREASURY_PALLET_ID)).into();
 }
 
@@ -199,7 +199,10 @@ impl xcm_executor::Config for XcmConfig {
 	type MaxAssetsIntoHolding = ConstU32<8>;
 	type AssetLocker = ();
 	type AssetExchanger = ();
-	type FeeManager = XcmFeesToAccount<Self, WaivedLocations, AccountId, TreasuryAccount>;
+	type FeeManager = XcmFeeManagerFromComponents<
+		WaivedLocations,
+		XcmFeeToAccount<Self::AssetTransactor, AccountId, TreasuryAccount>,
+	>;
 	type MessageExporter = ();
 	type UniversalAliases = Nothing;
 	type CallDispatcher = RuntimeCall;

polkadot/runtime/rococo/src/xcm_config.rs

@@ -43,7 +43,8 @@ use xcm_builder::{
 	DescribeFamily, FixedWeightBounds, HashedDescription, IsChildSystemParachain, IsConcrete,
 	MintLocation, OriginToPluralityVoice, SignedAccountId32AsNative, SignedToAccountId32,
 	SovereignSignedViaLocation, TakeWeightCredit, TrailingSetTopicAsId, UsingComponents,
-	WeightInfoBounds, WithComputedOrigin, WithUniqueTopic, XcmFeesToAccount,
+	WeightInfoBounds, WithComputedOrigin, WithUniqueTopic, XcmFeeManagerFromComponents,
+	XcmFeeToAccount,
 };
 use xcm_executor::XcmExecutor;
 
@@ -53,7 +54,7 @@ parameter_types! {
 	pub UniversalLocation: InteriorMultiLocation = ThisNetwork::get().into();
 	pub CheckAccount: AccountId = XcmPallet::check_account();
 	pub LocalCheckAccount: (AccountId, MintLocation) = (CheckAccount::get(), MintLocation::Local);
-	pub TreasuryAccount: Option<AccountId> = Some(Treasury::account_id());
+	pub TreasuryAccount: AccountId = Treasury::account_id();
 }
 
 pub type LocationConverter = (
@@ -191,7 +192,10 @@ impl xcm_executor::Config for XcmConfig {
 	type SubscriptionService = XcmPallet;
 	type PalletInstancesInfo = AllPalletsWithSystem;
 	type MaxAssetsIntoHolding = MaxAssetsIntoHolding;
-	type FeeManager = XcmFeesToAccount<Self, SystemParachains, AccountId, TreasuryAccount>;
+	type FeeManager = XcmFeeManagerFromComponents<
+		SystemParachains,
+		XcmFeeToAccount<Self::AssetTransactor, AccountId, TreasuryAccount>,
+	>;
 	type MessageExporter = ();
 	type UniversalAliases = Nothing;
 	type CallDispatcher = RuntimeCall;

polkadot/runtime/westend/src/xcm_config.rs

@@ -44,7 +44,7 @@ use xcm_builder::{
 	DescribeFamily, HashedDescription, IsConcrete, MintLocation, OriginToPluralityVoice,
 	SignedAccountId32AsNative, SignedToAccountId32, SovereignSignedViaLocation, TakeWeightCredit,
 	TrailingSetTopicAsId, UsingComponents, WeightInfoBounds, WithComputedOrigin, WithUniqueTopic,
-	XcmFeesToAccount,
+	XcmFeeManagerFromComponents, XcmFeeToAccount,
 };
 use xcm_executor::XcmExecutor;
 
@@ -54,7 +54,7 @@ parameter_types! {
 	pub const UniversalLocation: InteriorMultiLocation = X1(GlobalConsensus(ThisNetwork::get()));
 	pub CheckAccount: AccountId = XcmPallet::check_account();
 	pub LocalCheckAccount: (AccountId, MintLocation) = (CheckAccount::get(), MintLocation::Local);
-	pub TreasuryAccount: Option<AccountId> = Some(Treasury::account_id());
+	pub TreasuryAccount: AccountId = Treasury::account_id();
 	/// The asset ID for the asset that we use to pay for message delivery fees.
 	pub FeeAssetId: AssetId = Concrete(TokenLocation::get());
 	/// The base fee for the message delivery fees.
@@ -185,7 +185,10 @@ impl xcm_executor::Config for XcmConfig {
 	type SubscriptionService = XcmPallet;
 	type PalletInstancesInfo = AllPalletsWithSystem;
 	type MaxAssetsIntoHolding = MaxAssetsIntoHolding;
-	type FeeManager = XcmFeesToAccount<Self, SystemParachains, AccountId, TreasuryAccount>;
+	type FeeManager = XcmFeeManagerFromComponents<
+		SystemParachains,
+		XcmFeeToAccount<Self::AssetTransactor, AccountId, TreasuryAccount>,
+	>;
 	type MessageExporter = ();
 	type UniversalAliases = Nothing;
 	type CallDispatcher = RuntimeCall;

polkadot/xcm/pallet-xcm-benchmarks/src/generic/benchmarking.rs

@@ -561,7 +561,7 @@ benchmarks! {
 		let (expected_fees_mode, expected_assets_in_holding) = T::DeliveryHelper::ensure_successful_delivery(
 			&origin,
 			&destination.into(),
-			FeeReason::Export(network),
+			FeeReason::Export { network, destination },
 		);
 		let sender_account = T::AccountIdConverter::convert_location(&origin).unwrap();
 		let sender_account_balance_before = T::TransactAsset::balance(&sender_account);

polkadot/xcm/pallet-xcm/src/mock.rs

@@ -34,7 +34,7 @@ use xcm_builder::{
 	AllowTopLevelPaidExecutionFrom, Case, ChildParachainAsNative, ChildParachainConvertsVia,
 	ChildSystemParachainAsSuperuser, CurrencyAdapter as XcmCurrencyAdapter, FixedRateOfFungible,
 	FixedWeightBounds, IsConcrete, SignedAccountId32AsNative, SignedToAccountId32,
-	SovereignSignedViaLocation, TakeWeightCredit, XcmFeesToAccount,
+	SovereignSignedViaLocation, TakeWeightCredit, XcmFeeManagerFromComponents, XcmFeeToAccount,
 };
 use xcm_executor::XcmExecutor;
 
@@ -343,11 +343,9 @@ impl xcm_executor::Config for XcmConfig {
 	type SubscriptionService = XcmPallet;
 	type PalletInstancesInfo = AllPalletsWithSystem;
 	type MaxAssetsIntoHolding = MaxAssetsIntoHolding;
-	type FeeManager = XcmFeesToAccount<
+	type FeeManager = XcmFeeManagerFromComponents<
-		Self,
 		EverythingBut<XcmFeesNotWaivedLocations>,
-		AccountId,
+		XcmFeeToAccount<Self::AssetTransactor, AccountId, XcmFeesTargetAccount>,
-		XcmFeesTargetAccount,
 	>;
 	type MessageExporter = ();
 	type UniversalAliases = Nothing;

polkadot/xcm/xcm-builder/src/fee_handling.rs

@@ -19,40 +19,103 @@ use frame_support::traits::{Contains, Get};
 use xcm::prelude::*;
 use xcm_executor::traits::{FeeManager, FeeReason, TransactAsset};
 
-/// A `FeeManager` implementation that simply deposits the fees handled into a specific on-chain
+/// Handles the fees that are taken by certain XCM instructions.
-/// `ReceiverAccount`.
+pub trait HandleFee {
-///
+	/// Do something with the fee which has been paid. Doing nothing here silently burns the
-/// It reuses the `AssetTransactor` configured on the XCM executor to deposit fee assets, and also
+	/// fees.
-/// permits specifying `WaivedLocations` for locations that are privileged to not pay for fees. If
+	///
-/// the `AssetTransactor` returns an error while calling `deposit_asset`, then a warning will be
+	/// Returns any part of the fee that wasn't consumed.
-/// logged.
+	fn handle_fee(fee: MultiAssets, context: Option<&XcmContext>, reason: FeeReason)
-pub struct XcmFeesToAccount<XcmConfig, WaivedLocations, AccountId, ReceiverAccount>(
+		-> MultiAssets;
-	PhantomData<(XcmConfig, WaivedLocations, AccountId, ReceiverAccount)>,
+}
+
+// Default `HandleFee` implementation that just burns the fee.
+impl HandleFee for () {
+	fn handle_fee(_: MultiAssets, _: Option<&XcmContext>, _: FeeReason) -> MultiAssets {
+		MultiAssets::new()
+	}
+}
+
+#[impl_trait_for_tuples::impl_for_tuples(1, 30)]
+impl HandleFee for Tuple {
+	fn handle_fee(
+		fee: MultiAssets,
+		context: Option<&XcmContext>,
+		reason: FeeReason,
+	) -> MultiAssets {
+		let mut unconsumed_fee = fee;
+		for_tuples!( #(
+			unconsumed_fee = Tuple::handle_fee(unconsumed_fee, context, reason);
+			if unconsumed_fee.is_none() {
+				return unconsumed_fee;
+			}
+		)* );
+
+		unconsumed_fee
+	}
+}
+
+/// A `FeeManager` implementation that permits the specified `WaivedLocations` to not pay for fees
+/// and that uses the provided `HandleFee` implementation otherwise.
+pub struct XcmFeeManagerFromComponents<WaivedLocations, HandleFee>(
+	PhantomData<(WaivedLocations, HandleFee)>,
 );
-impl<
+impl<WaivedLocations: Contains<MultiLocation>, FeeHandler: HandleFee> FeeManager
-		XcmConfig: xcm_executor::Config,
+	for XcmFeeManagerFromComponents<WaivedLocations, FeeHandler>
-		WaivedLocations: Contains<MultiLocation>,
-		AccountId: Clone + Into<[u8; 32]>,
-		ReceiverAccount: Get<Option<AccountId>>,
-	> FeeManager for XcmFeesToAccount<XcmConfig, WaivedLocations, AccountId, ReceiverAccount>
 {
 	fn is_waived(origin: Option<&MultiLocation>, _: FeeReason) -> bool {
 		let Some(loc) = origin else { return false };
 		WaivedLocations::contains(loc)
 	}
 
-	fn handle_fee(fees: MultiAssets, context: Option<&XcmContext>) {
+	fn handle_fee(fee: MultiAssets, context: Option<&XcmContext>, reason: FeeReason) {
-		if let Some(receiver) = ReceiverAccount::get() {
+		FeeHandler::handle_fee(fee, context, reason);
-			let dest = AccountId32 { network: None, id: receiver.into() }.into();
+	}
-			for asset in fees.into_inner() {
+}
-				if let Err(e) = XcmConfig::AssetTransactor::deposit_asset(&asset, &dest, context) {
+
-					log::trace!(
+/// Try to deposit the given fee in the specified account.
-						target: "xcm::fees",
+/// Burns the fee in case of a failure.
-						"`AssetTransactor::deposit_asset` returned error: {:?}, burning fees: {:?}",
+pub fn deposit_or_burn_fee<AssetTransactor: TransactAsset, AccountId: Clone + Into<[u8; 32]>>(
-						e, asset,
+	fee: MultiAssets,
-					);
+	context: Option<&XcmContext>,
-				}
+	receiver: AccountId,
-			}
+) {
+	let dest = AccountId32 { network: None, id: receiver.into() }.into();
+	for asset in fee.into_inner() {
+		if let Err(e) = AssetTransactor::deposit_asset(&asset, &dest, context) {
+			log::trace!(
+				target: "xcm::fees",
+				"`AssetTransactor::deposit_asset` returned error: {:?}. Burning fee: {:?}. \
+				They might be burned.",
+				e, asset,
+			);
 		}
 	}
 }
+
+/// A `HandleFee` implementation that simply deposits the fees into a specific on-chain
+/// `ReceiverAccount`.
+///
+/// It reuses the `AssetTransactor` configured on the XCM executor to deposit fee assets. If
+/// the `AssetTransactor` returns an error while calling `deposit_asset`, then a warning will be
+/// logged and the fee burned.
+pub struct XcmFeeToAccount<AssetTransactor, AccountId, ReceiverAccount>(
+	PhantomData<(AssetTransactor, AccountId, ReceiverAccount)>,
+);
+
+impl<
+		AssetTransactor: TransactAsset,
+		AccountId: Clone + Into<[u8; 32]>,
+		ReceiverAccount: Get<AccountId>,
+	> HandleFee for XcmFeeToAccount<AssetTransactor, AccountId, ReceiverAccount>
+{
+	fn handle_fee(
+		fee: MultiAssets,
+		context: Option<&XcmContext>,
+		_reason: FeeReason,
+	) -> MultiAssets {
+		deposit_or_burn_fee::<AssetTransactor, _>(fee, context, ReceiverAccount::get());
+
+		MultiAssets::new()
+	}
+}

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

@@ -68,7 +68,9 @@ mod currency_adapter;
 pub use currency_adapter::CurrencyAdapter;
 
 mod fee_handling;
-pub use fee_handling::XcmFeesToAccount;
+pub use fee_handling::{
+	deposit_or_burn_fee, HandleFee, XcmFeeManagerFromComponents, XcmFeeToAccount,
+};
 
 mod fungibles_adapter;
 pub use fungibles_adapter::{

polkadot/xcm/xcm-builder/src/tests/mock.rs

@@ -526,7 +526,8 @@ impl FeeManager for TestFeeManager {
 	fn is_waived(_: Option<&MultiLocation>, r: FeeReason) -> bool {
 		IS_WAIVED.with(|l| l.borrow().contains(&r))
 	}
-	fn handle_fee(_: MultiAssets, _: Option<&XcmContext>) {}
+
+	fn handle_fee(_: MultiAssets, _: Option<&XcmContext>, _: FeeReason) {}
 }
 
 #[derive(Clone, Eq, PartialEq, Debug)]

polkadot/xcm/xcm-executor/src/lib.rs

@@ -248,7 +248,7 @@ impl<Config: config::Config> ExecuteXcm<Config::RuntimeCall> for XcmExecutor<Con
 			for asset in fees.inner() {
 				Config::AssetTransactor::withdraw_asset(&asset, &origin, None)?;
 			}
-			Config::FeeManager::handle_fee(fees, None);
+			Config::FeeManager::handle_fee(fees, None, FeeReason::ChargeFees);
 		}
 		Ok(())
 	}
@@ -851,7 +851,7 @@ impl<Config: config::Config> XcmExecutor<Config> {
 					destination,
 					xcm,
 				)?;
-				self.take_fee(fee, FeeReason::Export(network))?;
+				self.take_fee(fee, FeeReason::Export { network, destination })?;
 				Config::MessageExporter::deliver(ticket)?;
 				Ok(())
 			},
@@ -962,7 +962,7 @@ impl<Config: config::Config> XcmExecutor<Config> {
 		} else {
 			self.holding.try_take(fee.into()).map_err(|_| XcmError::NotHoldingFees)?.into()
 		};
-		Config::FeeManager::handle_fee(paid, Some(&self.context));
+		Config::FeeManager::handle_fee(paid, Some(&self.context), reason);
 		Ok(())
 	}
 

polkadot/xcm/xcm-executor/src/traits/fee_manager.rs

@@ -18,12 +18,12 @@ use xcm::prelude::*;
 
 /// Handle stuff to do with taking fees in certain XCM instructions.
 pub trait FeeManager {
-	/// Determine if a fee which would normally payable should be waived.
+	/// Determine if a fee should be waived.
 	fn is_waived(origin: Option<&MultiLocation>, r: FeeReason) -> bool;
 
 	/// Do something with the fee which has been paid. Doing nothing here silently burns the
 	/// fees.
-	fn handle_fee(fee: MultiAssets, context: Option<&XcmContext>);
+	fn handle_fee(fee: MultiAssets, context: Option<&XcmContext>, r: FeeReason);
 }
 
 /// Context under which a fee is paid.
@@ -42,7 +42,7 @@ pub enum FeeReason {
 	/// When the `QueryPallet` instruction is called.
 	QueryPallet,
 	/// When the `ExportMessage` instruction is called (and includes the network ID).
-	Export(NetworkId),
+	Export { network: NetworkId, destination: InteriorMultiLocation },
 	/// The `charge_fees` API.
 	ChargeFees,
 	/// When the `LockAsset` instruction is called.
@@ -55,5 +55,6 @@ impl FeeManager for () {
 	fn is_waived(_: Option<&MultiLocation>, _: FeeReason) -> bool {
 		false
 	}
-	fn handle_fee(_: MultiAssets, _: Option<&XcmContext>) {}
+
+	fn handle_fee(_: MultiAssets, _: Option<&XcmContext>, _: FeeReason) {}
 }