Local Pluralities Get Free Xcm Execution

relay/kusama/src/xcm_config.rs

@@ -147,6 +147,9 @@ match_types! {
 	pub type OnlyParachains: impl Contains<MultiLocation> = {
 		MultiLocation { parents: 0, interior: X1(Parachain(_)) }
 	};
+	pub type LocalPlurality: impl Contains<MultiLocation> = {
+		MultiLocation { parents: 0, interior: X1(Plurality { .. }) }
+	};
 }
 
 /// The barriers one of which must be passed for an XCM message to be executed.
@@ -321,6 +324,10 @@ impl Contains<RuntimeCall> for SafeCallFilter {
 	}
 }
 
+/// Locations that will not be charged fees in the executor, either execution or delivery.
+/// We only waive fees for system functions, which these locations represent.
+pub type WaivedLocations = (SystemParachains, LocalPlurality);
+
 pub struct XcmConfig;
 impl xcm_executor::Config for XcmConfig {
 	type RuntimeCall = RuntimeCall;
@@ -347,7 +354,7 @@ impl xcm_executor::Config for XcmConfig {
 	type SubscriptionService = XcmPallet;
 	type PalletInstancesInfo = AllPalletsWithSystem;
 	type MaxAssetsIntoHolding = MaxAssetsIntoHolding;
-	type FeeManager = XcmFeesToAccount<Self, SystemParachains, AccountId, TreasuryAccount>;
+	type FeeManager = XcmFeesToAccount<Self, WaivedLocations, AccountId, TreasuryAccount>;
 	// No bridges yet...
 	type MessageExporter = ();
 	type UniversalAliases = Nothing;

relay/polkadot/src/xcm_config.rs

@@ -161,6 +161,9 @@ match_types! {
 		MultiLocation { parents: 0, interior: X1(Parachain(COLLECTIVES_ID)) } |
 		MultiLocation { parents: 0, interior: X2(Parachain(COLLECTIVES_ID), Plurality { id: BodyId::Technical, .. }) }
 	};
+	pub type LocalPlurality: impl Contains<MultiLocation> = {
+		MultiLocation { parents: 0, interior: X1(Plurality { .. }) }
+	};
 }
 
 /// The barriers one of which must be passed for an XCM message to be executed.
@@ -324,6 +327,10 @@ impl Contains<RuntimeCall> for SafeCallFilter {
 	}
 }
 
+/// Locations that will not be charged fees in the executor, either execution or delivery.
+/// We only waive fees for system functions, which these locations represent.
+pub type WaivedLocations = (SystemParachains, LocalPlurality);
+
 pub struct XcmConfig;
 impl xcm_executor::Config for XcmConfig {
 	type RuntimeCall = RuntimeCall;
@@ -351,7 +358,7 @@ impl xcm_executor::Config for XcmConfig {
 	type SubscriptionService = XcmPallet;
 	type PalletInstancesInfo = AllPalletsWithSystem;
 	type MaxAssetsIntoHolding = MaxAssetsIntoHolding;
-	type FeeManager = XcmFeesToAccount<Self, SystemParachains, AccountId, TreasuryAccount>;
+	type FeeManager = XcmFeesToAccount<Self, WaivedLocations, AccountId, TreasuryAccount>;
 	// No bridges yet...
 	type MessageExporter = ();
 	type UniversalAliases = Nothing;

system-parachains/collectives/collectives-polkadot/src/fellowship/mod.rs

@@ -19,9 +19,12 @@
 mod origins;
 mod tracks;
 use crate::{
-	impls::ToParentTreasury, weights, xcm_config::TreasurerBodyId, AccountId, AssetRate, Balance,
-	Balances, FellowshipReferenda, GovernanceLocation, PolkadotTreasuryAccount, Preimage, Runtime,
-	RuntimeCall, RuntimeEvent, RuntimeOrigin, Scheduler, DAYS,
+	impls::ToParentTreasury,
+	weights,
+	xcm_config::{LocationToAccountId, TreasurerBodyId},
+	AccountId, AssetRate, Balance, Balances, FellowshipReferenda, GovernanceLocation,
+	PolkadotTreasuryAccount, Preimage, Runtime, RuntimeCall, RuntimeEvent, RuntimeOrigin,
+	Scheduler, DAYS,
 };
 use cumulus_primitives_core::Junction::GeneralIndex;
 use frame_support::{
@@ -38,16 +41,13 @@ pub use origins::{
 };
 use pallet_ranked_collective::EnsureOfRank;
 use pallet_xcm::{EnsureXcm, IsVoiceOfBody};
-use parachains_common::polkadot::account;
 use polkadot_runtime_common::impls::{
 	LocatableAssetConverter, VersionedLocatableAsset, VersionedMultiLocationConverter,
 };
 use polkadot_runtime_constants::{currency::GRAND, time::HOURS, xcm::body::FELLOWSHIP_ADMIN_INDEX};
 use sp_arithmetic::Permill;
 use sp_core::{ConstU128, ConstU32};
-use sp_runtime::traits::{
-	AccountIdConversion, ConstU16, ConvertToValue, IdentityLookup, Replace, TakeFirst,
-};
+use sp_runtime::traits::{ConstU16, ConvertToValue, IdentityLookup, Replace, TakeFirst};
 use xcm::latest::BodyId;
 use xcm_builder::{AliasesIntoAccountId32, LocatableAssetId, PayOverXcm};
 
@@ -70,8 +70,6 @@ pub mod ranks {
 }
 
 parameter_types! {
-	// Referenda pallet account, used to temporarily deposit slashed imbalance before teleporting.
-	pub ReferendaPalletAccount: AccountId = account::REFERENDA_PALLET_ID.into_account_truncating();
 	pub const FellowshipAdminBodyId: BodyId = BodyId::Index(FELLOWSHIP_ADMIN_INDEX);
 }
 
@@ -101,7 +99,7 @@ impl pallet_referenda::Config<FellowshipReferendaInstance> for Runtime {
 	>;
 	type CancelOrigin = Architects;
 	type KillOrigin = Masters;
-	type Slash = ToParentTreasury<PolkadotTreasuryAccount, ReferendaPalletAccount, Runtime>;
+	type Slash = ToParentTreasury<PolkadotTreasuryAccount, LocationToAccountId, Runtime>;
 	type Votes = pallet_ranked_collective::Votes;
 	type Tally = pallet_ranked_collective::TallyOf<Runtime, FellowshipCollectiveInstance>;
 	type SubmissionDeposit = ConstU128<0>;

system-parachains/collectives/collectives-polkadot/src/impls.rs

@@ -24,7 +24,8 @@ use pallet_alliance::{ProposalIndex, ProposalProvider};
 use parachains_common::impls::NegativeImbalance;
 use sp_runtime::DispatchError;
 use sp_std::{cmp::Ordering, marker::PhantomData, prelude::*};
-use xcm::latest::{Fungibility, Junction, Parent, WeightLimit};
+use xcm::latest::{Fungibility, Junction, Junctions::Here, MultiLocation, Parent, WeightLimit};
+use xcm_executor::traits::ConvertLocation;
 
 type AccountIdOf<T> = <T as frame_system::Config>::AccountId;
 
@@ -38,36 +39,44 @@ pub type BalanceOf<T> =
 
 /// Implements `OnUnbalanced::on_unbalanced` to teleport slashed assets to relay chain treasury
 /// account.
-pub struct ToParentTreasury<TreasuryAccount, PalletAccount, T>(
-	PhantomData<(TreasuryAccount, PalletAccount, T)>,
+pub struct ToParentTreasury<TreasuryAccount, AccountIdConverter, T>(
+	PhantomData<(TreasuryAccount, AccountIdConverter, T)>,
 );
 
-impl<TreasuryAccount, PalletAccount, T> OnUnbalanced<NegativeImbalance<T>>
-	for ToParentTreasury<TreasuryAccount, PalletAccount, T>
+impl<TreasuryAccount, AccountIdConverter, T> OnUnbalanced<NegativeImbalance<T>>
+	for ToParentTreasury<TreasuryAccount, AccountIdConverter, T>
 where
 	T: pallet_balances::Config + pallet_xcm::Config + frame_system::Config,
 	<<T as frame_system::Config>::RuntimeOrigin as OriginTrait>::AccountId: From<AccountIdOf<T>>,
 	[u8; 32]: From<<T as frame_system::Config>::AccountId>,
 	TreasuryAccount: Get<AccountIdOf<T>>,
-	PalletAccount: Get<AccountIdOf<T>>,
 	BalanceOf<T>: Into<Fungibility>,
+	AccountIdConverter: ConvertLocation<AccountIdOf<T>>,
 {
 	fn on_unbalanced(amount: NegativeImbalance<T>) {
 		let amount = match amount.drop_zero() {
 			Ok(..) => return,
 			Err(amount) => amount,
 		};
 		let imbalance = amount.peek();
-		let pallet_acc: AccountIdOf<T> = PalletAccount::get();
-		let treasury_acc: AccountIdOf<T> = TreasuryAccount::get();
-
-		<pallet_balances::Pallet<T>>::resolve_creating(&pallet_acc, amount);
+		let root_location: MultiLocation = Here.into();
+		let root_account: AccountIdOf<T> =
+			match AccountIdConverter::convert_location(&root_location) {
+				Some(a) => a,
+				None => {
+					log::warn!("Failed to convert root origin into account id");
+					return
+				},
+			};
+		let treasury_account: AccountIdOf<T> = TreasuryAccount::get();
+
+		<pallet_balances::Pallet<T>>::resolve_creating(&root_account, amount);
 
 		let result = <pallet_xcm::Pallet<T>>::limited_teleport_assets(
-			<<T as frame_system::Config>::RuntimeOrigin>::signed(pallet_acc.into()),
+			<<T as frame_system::Config>::RuntimeOrigin>::root(),
 			Box::new(Parent.into()),
 			Box::new(
-				Junction::AccountId32 { network: None, id: treasury_acc.into() }
+				Junction::AccountId32 { network: None, id: treasury_account.into() }
 					.into_location()
 					.into(),
 			),

system-parachains/collectives/collectives-polkadot/src/lib.rs

@@ -87,7 +87,8 @@ use parachains_common::{
 };
 use sp_runtime::RuntimeDebug;
 use xcm_config::{
-	GovernanceLocation, TreasurerBodyId, XcmConfig, XcmOriginToTransactDispatchOrigin,
+	GovernanceLocation, LocationToAccountId, TreasurerBodyId, XcmConfig,
+	XcmOriginToTransactDispatchOrigin,
 };
 
 #[cfg(any(feature = "std", test))]
@@ -509,9 +510,6 @@ pub const MAX_ALLIES: u32 = 100;
 
 parameter_types! {
 	pub const AllyDeposit: Balance = 1_000 * UNITS; // 1,000 DOT bond to join as an Ally
-	// The Alliance pallet account, used as a temporary place to deposit a slashed imbalance
-	// before the teleport to the Treasury.
-	pub AlliancePalletAccount: AccountId = ALLIANCE_PALLET_ID.into_account_truncating();
 	pub PolkadotTreasuryAccount: AccountId = POLKADOT_TREASURY_PALLET_ID.into_account_truncating();
 	// The number of blocks a member must wait between giving a retirement notice and retiring.
 	// Supposed to be greater than time required to `kick_member` with alliance motion.
@@ -525,7 +523,7 @@ impl pallet_alliance::Config for Runtime {
 	type MembershipManager = RootOrAllianceTwoThirdsMajority;
 	type AnnouncementOrigin = RootOrAllianceTwoThirdsMajority;
 	type Currency = Balances;
-	type Slashed = ToParentTreasury<PolkadotTreasuryAccount, AlliancePalletAccount, Runtime>;
+	type Slashed = ToParentTreasury<PolkadotTreasuryAccount, LocationToAccountId, Runtime>;
 	type InitializeMembers = AllianceMotion;
 	type MembershipChanged = AllianceMotion;
 	type RetirementPeriod = AllianceRetirementPeriod;

system-parachains/collectives/collectives-polkadot/src/xcm_config.rs

@@ -132,6 +132,9 @@ match_types! {
 		MultiLocation { parents: 1, interior: Here } |
 		MultiLocation { parents: 1, interior: X1(_) }
 	};
+	pub type LocalPlurality: impl Contains<MultiLocation> = {
+		MultiLocation { parents: 0, interior: X1(Plurality { .. }) }
+	};
 }
 
 /// A call filter for the XCM Transact instruction. This is a temporary measure until we properly
@@ -261,8 +264,11 @@ match_types! {
 /// Locations that will not be charged fees in the executor,
 /// either execution or delivery.
 /// We only waive fees for system functions, which these locations represent.
-pub type WaivedLocations =
-	(RelayOrOtherSystemParachains<SystemParachains, Runtime>, Equals<RelayTreasuryLocation>);
+pub type WaivedLocations = (
+	RelayOrOtherSystemParachains<SystemParachains, Runtime>,
+	Equals<RelayTreasuryLocation>,
+	LocalPlurality,
+);
 
 /// Cases where a remote origin is accepted as trusted Teleporter for a given asset:
 /// - DOT with the parent Relay Chain and sibling parachains.