Make a struct in xcm_primitives with the required bounds

primitives/xcm/src/lib.rs

@@ -19,7 +19,7 @@
 #![cfg_attr(not(feature = "std"), no_std)]
 
 use frame_support::{
-	traits::{Get, OriginTrait},
+	traits::{tokens::fungibles::Mutate, Get, OriginTrait},
 	weights::{constants::WEIGHT_PER_SECOND, Weight},
 };
 use xcm::latest::{
@@ -29,8 +29,7 @@ use xcm::latest::{
 	MultiAsset, MultiLocation, NetworkId,
 };
 use xcm_builder::TakeRevenue;
-use xcm_executor::traits::FilterAssetLocation;
-use xcm_executor::traits::WeightTrader;
+use xcm_executor::traits::{FilterAssetLocation, MatchesFungibles, WeightTrader};
 
 use sp_std::borrow::Borrow;
 use sp_std::{convert::TryInto, marker::PhantomData};
@@ -310,3 +309,21 @@ pub trait AccountIdToCurrencyId<Account, CurrencyId> {
 	// Get assetId from account
 	fn account_to_currency_id(account: Account) -> Option<CurrencyId>;
 }
+
+pub struct XcmFeesToAccount<Assets, Matcher, AccountId, ReceiverAccount>(
+	PhantomData<(Assets, Matcher, AccountId, ReceiverAccount)>,
+);
+impl<
+		Assets: Mutate<AccountId>,
+		Matcher: MatchesFungibles<Assets::AssetId, Assets::Balance>,
+		AccountId: Clone, // can't get away without it since Currency is generic over it.
+		ReceiverAccount: Get<AccountId>,
+	> TakeRevenue for XcmFeesToAccount<Assets, Matcher, AccountId, ReceiverAccount>
+{
+	fn take_revenue(revenue: MultiAsset) {
+		if let Ok((asset_id, amount)) = Matcher::matches_fungibles(&revenue) {
+			let ok = Assets::mint_into(asset_id, &ReceiverAccount::get(), amount).is_ok();
+			debug_assert!(ok, "`mint_into` cannot generally fail; qed");
+		}
+	}
+}

runtime/moonbase/src/lib.rs

@@ -33,7 +33,6 @@ use fp_rpc::TransactionStatus;
 use pallet_evm_precompile_assets_erc20::AccountIdAssetIdConversion;
 
 use account::AccountId20;
-use frame_support::traits::tokens::fungibles::Mutate;
 use sp_runtime::traits::Hash as THash;
 
 use frame_support::{
@@ -55,7 +54,7 @@ use xcm_builder::{
 	CurrencyAdapter as XcmCurrencyAdapter, EnsureXcmOrigin, FixedWeightBounds, FungiblesAdapter,
 	IsConcrete, LocationInverter, ParentAsSuperuser, ParentIsDefault, RelayChainAsNative,
 	SiblingParachainAsNative, SiblingParachainConvertsVia, SignedAccountKey20AsNative,
-	SovereignSignedViaLocation, TakeRevenue, TakeWeightCredit, UsingComponents,
+	SovereignSignedViaLocation, TakeWeightCredit, UsingComponents,
 };
 
 use xcm_executor::traits::JustTry;
@@ -106,7 +105,8 @@ use precompiles::{MoonbasePrecompiles, ASSET_PRECOMPILE_ADDRESS_PREFIX};
 
 use xcm_primitives::{
 	AccountIdToCurrencyId, AccountIdToMultiLocation, AsAssetType, FirstAssetTrader,
-	MultiNativeAsset, SignedToAccountId20, UtilityAvailableCalls, UtilityEncodeCall, XcmTransact,
+	MultiNativeAsset, SignedToAccountId20, UtilityAvailableCalls, UtilityEncodeCall,
+	XcmFeesToAccount, XcmTransact,
 };
 
 #[cfg(any(feature = "std", test))]
@@ -576,25 +576,6 @@ impl pallet_democracy::Config for Runtime {
 	type MaxProposals = MaxProposals;
 }
 
-pub struct ToTreasury<AssetXConverter>(sp_std::marker::PhantomData<AssetXConverter>);
-impl<AssetXConverter> TakeRevenue for ToTreasury<AssetXConverter>
-where
-	AssetXConverter: xcm_executor::traits::Convert<MultiLocation, AssetId>,
-{
-	fn take_revenue(revenue: MultiAsset) {
-		if let MultiAsset {
-			id: Concrete(location),
-			fun: Fungible(amount),
-		} = revenue
-		{
-			if let Some(asset_id) = AssetXConverter::convert_ref(location).ok() {
-				// Mint fees in treasury
-				let _ = Assets::mint_into(asset_id, &Treasury::account_id(), amount);
-			}
-		}
-	}
-}
-
 parameter_types! {
 	pub const ProposalBond: Permill = Permill::from_percent(5);
 	pub const ProposalBondMinimum: Balance = 1 * currency::UNIT * currency::SUPPLY_FACTOR;
@@ -1070,6 +1051,26 @@ pub type XcmBarrier = (
 	AllowSubscriptionsFrom<Everything>,
 );
 
+parameter_types! {
+	/// Xcm fees will go to the treasury account
+	pub TreasuryAccount:AccountId = Treasury::account_id();
+}
+
+/// This is the struct that will handle the revenue from xcm fees
+pub type XcmFeesToTreasury = XcmFeesToAccount<
+	Assets,
+	(
+		ConvertedConcreteAssetId<
+			AssetId,
+			Balance,
+			AsAssetType<AssetId, AssetType, AssetManager>,
+			JustTry,
+		>,
+	),
+	AccountId,
+	TreasuryAccount,
+>;
+
 pub struct XcmExecutorConfig;
 impl xcm_executor::Config for XcmExecutorConfig {
 	type Call = Call;
@@ -1095,12 +1096,7 @@ impl xcm_executor::Config for XcmExecutorConfig {
 			Balances,
 			DealWithFees<Runtime>,
 		>,
-		FirstAssetTrader<
-			AssetId,
-			AssetType,
-			AssetManager,
-			ToTreasury<AsAssetType<AssetId, AssetType, AssetManager>>,
-		>,
+		FirstAssetTrader<AssetId, AssetType, AssetManager, XcmFeesToTreasury>,
 	);
 	type ResponseHandler = PolkadotXcm;
 	type SubscriptionService = PolkadotXcm;

runtime/moonbase/tests/xcm_mock/parachain.rs

@@ -18,7 +18,7 @@
 
 use frame_support::{
 	construct_runtime, parameter_types,
-	traits::{tokens::fungibles::Mutate, Everything, Get, Nothing, PalletInfo as PalletInfoTrait},
+	traits::{Everything, Get, Nothing, PalletInfo as PalletInfoTrait},
 	weights::Weight,
 	PalletId,
 };
@@ -47,7 +47,7 @@ use xcm_builder::{
 	CurrencyAdapter as XcmCurrencyAdapter, EnsureXcmOrigin, FixedRateOfFungible, FixedWeightBounds,
 	FungiblesAdapter, IsConcrete, LocationInverter, ParentAsSuperuser, ParentIsDefault,
 	RelayChainAsNative, SiblingParachainAsNative, SiblingParachainConvertsVia,
-	SignedAccountKey20AsNative, SovereignSignedViaLocation, TakeRevenue, TakeWeightCredit,
+	SignedAccountKey20AsNative, SovereignSignedViaLocation, TakeWeightCredit,
 };
 use xcm_executor::{traits::JustTry, Config, XcmExecutor};
 
@@ -222,25 +222,26 @@ pub type Barrier = (
 	AllowSubscriptionsFrom<Everything>,
 );
 
-pub struct ToTreasury<AssetXConverter>(sp_std::marker::PhantomData<AssetXConverter>);
-impl<AssetXConverter> TakeRevenue for ToTreasury<AssetXConverter>
-where
-	AssetXConverter: xcm_executor::traits::Convert<MultiLocation, AssetId>,
-{
-	fn take_revenue(revenue: MultiAsset) {
-		if let MultiAsset {
-			id: Concrete(location),
-			fun: Fungible(amount),
-		} = revenue
-		{
-			if let Some(asset_id) = AssetXConverter::convert_ref(location).ok() {
-				// Mint fees in treasury
-				let _ = Assets::mint_into(asset_id, &Treasury::account_id(), amount);
-			}
-		}
-	}
+parameter_types! {
+	/// Xcm fees will go to the treasury account
+	pub TreasuryAccount:AccountId = Treasury::account_id();
 }
 
+/// This is the struct that will handle the revenue from xcm fees
+pub type XcmFeesToTreasury = xcm_primitives::XcmFeesToAccount<
+	Assets,
+	(
+		ConvertedConcreteAssetId<
+			AssetId,
+			Balance,
+			xcm_primitives::AsAssetType<AssetId, AssetType, AssetManager>,
+			JustTry,
+		>,
+	),
+	AccountId,
+	TreasuryAccount,
+>;
+
 parameter_types! {
 	// We cannot skip the native trader for some specific tests, so we will have to work with
 	// a native trader that charges same number of units as weight
@@ -272,12 +273,7 @@ impl Config for XcmConfig {
 	type Weigher = FixedWeightBounds<UnitWeightCost, Call, MaxInstructions>;
 	type Trader = (
 		FixedRateOfFungible<ParaTokensPerSecond, ()>,
-		xcm_primitives::FirstAssetTrader<
-			AssetId,
-			AssetType,
-			AssetManager,
-			ToTreasury<xcm_primitives::AsAssetType<AssetId, AssetType, AssetManager>>,
-		>,
+		xcm_primitives::FirstAssetTrader<AssetId, AssetType, AssetManager, XcmFeesToTreasury>,
 	);
 
 	type ResponseHandler = PolkadotXcm;