FRAME: Unity Balance Conversion for Different IDs of Native Asset (#3659)

Introduce types to define 1:1 balance conversion for different relative
asset ids/locations of native asset.

Examples:
native asset on Asset Hub presented as `VersionedLocatableAsset` type in
the context of Relay Chain is
```
{
  `location`: (0, Parachain(1000)),
  `asset_id`: (1, Here),
}
```
and it's balance should be converted 1:1 by implementations of
`ConversionToAssetBalance` trait.

---------

Co-authored-by: Branislav Kontur <bkontur@gmail.com>

polkadot/runtime/common/src/impls.rs

@@ -19,7 +19,7 @@
 use frame_support::traits::{
 	fungible::{Balanced, Credit},
 	tokens::imbalance::ResolveTo,
-	Imbalance, OnUnbalanced,
+	Contains, ContainsPair, Imbalance, OnUnbalanced,
 };
 use pallet_treasury::TreasuryAccountId;
 use parity_scale_codec::{Decode, Encode, MaxEncodedLen};
@@ -156,6 +156,26 @@ impl TryConvert<&VersionedLocation, xcm::latest::Location> for VersionedLocation
 	}
 }
 
+/// Adapter for [`Contains`] trait to match [`VersionedLocatableAsset`] type converted to the latest
+/// version of itself where it's location matched by `L` and it's asset id by `A` parameter types.
+pub struct ContainsParts<C>(core::marker::PhantomData<C>);
+impl<C> Contains<VersionedLocatableAsset> for ContainsParts<C>
+where
+	C: ContainsPair<xcm::latest::Location, xcm::latest::Location>,
+{
+	fn contains(asset: &VersionedLocatableAsset) -> bool {
+		use VersionedLocatableAsset::*;
+		let (location, asset_id) = match asset.clone() {
+			V3 { location, asset_id } => match (location.try_into(), asset_id.try_into()) {
+				(Ok(l), Ok(a)) => (l, a),
+				_ => return false,
+			},
+			V4 { location, asset_id } => (location, asset_id),
+		};
+		C::contains(&location, &asset_id.0)
+	}
+}
+
 #[cfg(feature = "runtime-benchmarks")]
 pub mod benchmarks {
 	use super::VersionedLocatableAsset;

polkadot/runtime/rococo/src/lib.rs

@@ -25,7 +25,10 @@ use beefy_primitives::{
 	ecdsa_crypto::{AuthorityId as BeefyId, Signature as BeefySignature},
 	mmr::{BeefyDataProvider, MmrLeafVersion},
 };
-use frame_support::dynamic_params::{dynamic_pallet_params, dynamic_params};
+use frame_support::{
+	dynamic_params::{dynamic_pallet_params, dynamic_params},
+	traits::FromContains,
+};
 use pallet_nis::WithMaximumOf;
 use parity_scale_codec::{Decode, Encode, MaxEncodedLen};
 use primitives::{
@@ -40,7 +43,8 @@ use rococo_runtime_constants::system_parachain::BROKER_ID;
 use runtime_common::{
 	assigned_slots, auctions, claims, crowdloan, identity_migrator, impl_runtime_weights,
 	impls::{
-		LocatableAssetConverter, ToAuthor, VersionedLocatableAsset, VersionedLocationConverter,
+		ContainsParts, LocatableAssetConverter, ToAuthor, VersionedLocatableAsset,
+		VersionedLocationConverter,
 	},
 	paras_registrar, paras_sudo_wrapper, prod_or_fast, slots,
 	traits::{Leaser, OnSwap},
@@ -74,10 +78,10 @@ use frame_support::{
 	genesis_builder_helper::{build_state, get_preset},
 	parameter_types,
 	traits::{
-		fungible::HoldConsideration, Contains, EitherOf, EitherOfDiverse, EnsureOrigin,
-		EnsureOriginWithArg, EverythingBut, InstanceFilter, KeyOwnerProofSystem,
-		LinearStoragePrice, PrivilegeCmp, ProcessMessage, ProcessMessageError, StorageMapShim,
-		WithdrawReasons,
+		fungible::HoldConsideration, tokens::UnityOrOuterConversion, Contains, EitherOf,
+		EitherOfDiverse, EnsureOrigin, EnsureOriginWithArg, EverythingBut, InstanceFilter,
+		KeyOwnerProofSystem, LinearStoragePrice, PrivilegeCmp, ProcessMessage, ProcessMessageError,
+		StorageMapShim, WithdrawReasons,
 	},
 	weights::{ConstantMultiplier, WeightMeter, WeightToFee as _},
 	PalletId,
@@ -87,7 +91,7 @@ use pallet_grandpa::{fg_primitives, AuthorityId as GrandpaId};
 use pallet_identity::legacy::IdentityInfo;
 use pallet_session::historical as session_historical;
 use pallet_transaction_payment::{FeeDetails, FungibleAdapter, RuntimeDispatchInfo};
-use sp_core::{ConstU128, OpaqueMetadata, H256};
+use sp_core::{ConstU128, ConstU8, OpaqueMetadata, H256};
 use sp_runtime::{
 	create_runtime_str, generic, impl_opaque_keys,
 	traits::{
@@ -523,7 +527,15 @@ impl pallet_treasury::Config for Runtime {
 		LocatableAssetConverter,
 		VersionedLocationConverter,
 	>;
-	type BalanceConverter = AssetRate;
+	type BalanceConverter = UnityOrOuterConversion<
+		ContainsParts<
+			FromContains<
+				xcm_builder::IsChildSystemParachain<ParaId>,
+				xcm_builder::IsParentsOnly<ConstU8<1>>,
+			>,
+		>,
+		AssetRate,
+	>;
 	type PayoutPeriod = PayoutSpendPeriod;
 	#[cfg(feature = "runtime-benchmarks")]
 	type BenchmarkHelper = runtime_common::impls::benchmarks::TreasuryArguments;

polkadot/runtime/westend/src/lib.rs

@@ -31,9 +31,9 @@ use frame_support::{
 	genesis_builder_helper::{build_state, get_preset},
 	parameter_types,
 	traits::{
-		fungible::HoldConsideration, ConstU32, Contains, EitherOf, EitherOfDiverse, EverythingBut,
-		InstanceFilter, KeyOwnerProofSystem, LinearStoragePrice, ProcessMessage,
-		ProcessMessageError, WithdrawReasons,
+		fungible::HoldConsideration, tokens::UnityOrOuterConversion, ConstU32, Contains, EitherOf,
+		EitherOfDiverse, EverythingBut, FromContains, InstanceFilter, KeyOwnerProofSystem,
+		LinearStoragePrice, ProcessMessage, ProcessMessageError, WithdrawReasons,
 	},
 	weights::{ConstantMultiplier, WeightMeter, WeightToFee as _},
 	PalletId,
@@ -57,7 +57,8 @@ use runtime_common::{
 	elections::OnChainAccuracy,
 	identity_migrator, impl_runtime_weights,
 	impls::{
-		LocatableAssetConverter, ToAuthor, VersionedLocatableAsset, VersionedLocationConverter,
+		ContainsParts, LocatableAssetConverter, ToAuthor, VersionedLocatableAsset,
+		VersionedLocationConverter,
 	},
 	paras_registrar, paras_sudo_wrapper, prod_or_fast, slots,
 	traits::{Leaser, OnSwap},
@@ -80,7 +81,7 @@ use runtime_parachains::{
 	shared as parachains_shared,
 };
 use scale_info::TypeInfo;
-use sp_core::{OpaqueMetadata, RuntimeDebug, H256};
+use sp_core::{ConstU8, OpaqueMetadata, RuntimeDebug, H256};
 use sp_runtime::{
 	create_runtime_str,
 	curve::PiecewiseLinear,
@@ -712,7 +713,15 @@ impl pallet_treasury::Config for Runtime {
 		LocatableAssetConverter,
 		VersionedLocationConverter,
 	>;
-	type BalanceConverter = AssetRate;
+	type BalanceConverter = UnityOrOuterConversion<
+		ContainsParts<
+			FromContains<
+				xcm_builder::IsChildSystemParachain<ParaId>,
+				xcm_builder::IsParentsOnly<ConstU8<1>>,
+			>,
+		>,
+		AssetRate,
+	>;
 	type PayoutPeriod = PayoutSpendPeriod;
 	#[cfg(feature = "runtime-benchmarks")]
 	type BenchmarkHelper = runtime_common::impls::benchmarks::TreasuryArguments;

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

@@ -322,6 +322,29 @@ impl<ParaId: IsSystem + From<u32>> Contains<Location> for IsChildSystemParachain
 	}
 }
 
+/// Matches if the given location is a system-level sibling parachain.
+pub struct IsSiblingSystemParachain<ParaId, SelfParaId>(PhantomData<(ParaId, SelfParaId)>);
+impl<ParaId: IsSystem + From<u32> + Eq, SelfParaId: Get<ParaId>> Contains<Location>
+	for IsSiblingSystemParachain<ParaId, SelfParaId>
+{
+	fn contains(l: &Location) -> bool {
+		matches!(
+			l.unpack(),
+			(1, [Junction::Parachain(id)])
+				if SelfParaId::get() != ParaId::from(*id) && ParaId::from(*id).is_system(),
+		)
+	}
+}
+
+/// Matches if the given location contains only the specified amount of parents and no interior
+/// junctions.
+pub struct IsParentsOnly<Count>(PhantomData<Count>);
+impl<Count: Get<u8>> Contains<Location> for IsParentsOnly<Count> {
+	fn contains(t: &Location) -> bool {
+		t.contains_parents_only(Count::get())
+	}
+}
+
 /// Allows only messages if the generic `ResponseHandler` expects them via `expecting_response`.
 pub struct AllowKnownQueryResponses<ResponseHandler>(PhantomData<ResponseHandler>);
 impl<ResponseHandler: OnResponse> ShouldExecute for AllowKnownQueryResponses<ResponseHandler> {

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

@@ -37,8 +37,8 @@ mod barriers;
 pub use barriers::{
 	AllowExplicitUnpaidExecutionFrom, AllowKnownQueryResponses, AllowSubscriptionsFrom,
 	AllowTopLevelPaidExecutionFrom, AllowUnpaidExecutionFrom, DenyReserveTransferToRelayChain,
-	DenyThenTry, IsChildSystemParachain, RespectSuspension, TakeWeightCredit, TrailingSetTopicAsId,
-	WithComputedOrigin,
+	DenyThenTry, IsChildSystemParachain, IsParentsOnly, IsSiblingSystemParachain,
+	RespectSuspension, TakeWeightCredit, TrailingSetTopicAsId, WithComputedOrigin,
 };
 
 mod controller;