Asset Conversion: Pool Account ID derivation with additional Pallet ID seed (#3250)

Introduce `PalletId` as an additional seed parameter for pool's account
id derivation.

The PR also introduces the `pallet_asset_conversion_ops` pallet with a
call to migrate a given pool to thew new account. Additionally
`fungibles::lifetime::ResetTeam` and `fungible::lifetime::Refund`
traits, to facilitate the migration of pools.

---------

Co-authored-by: command-bot <>

substrate/frame/support/src/traits/tokens/fungible/union_of.rs

@@ -925,3 +925,28 @@ impl<
 		}
 	}
 }
+
+impl<
+		Left: fungible::Inspect<AccountId>,
+		Right: fungibles::Inspect<AccountId> + fungibles::Refund<AccountId>,
+		Criterion: Convert<AssetKind, Either<(), <Right as fungibles::Refund<AccountId>>::AssetId>>,
+		AssetKind: AssetId,
+		AccountId,
+	> fungibles::Refund<AccountId> for UnionOf<Left, Right, Criterion, AssetKind, AccountId>
+{
+	type AssetId = AssetKind;
+	type Balance = <Right as fungibles::Refund<AccountId>>::Balance;
+
+	fn deposit_held(asset: AssetKind, who: AccountId) -> Option<(AccountId, Self::Balance)> {
+		match Criterion::convert(asset) {
+			Left(()) => None,
+			Right(a) => <Right as fungibles::Refund<AccountId>>::deposit_held(a, who),
+		}
+	}
+	fn refund(asset: AssetKind, who: AccountId) -> DispatchResult {
+		match Criterion::convert(asset) {
+			Left(()) => Err(DispatchError::Unavailable),
+			Right(a) => <Right as fungibles::Refund<AccountId>>::refund(a, who),
+		}
+	}
+}

substrate/frame/support/src/traits/tokens/fungibles/lifetime.rs

@@ -15,13 +15,13 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//! Traits for creating and destroying assets.
+//! Traits for creating, editing and destroying assets.
 //!
 //! See the [`crate::traits::fungibles`] doc for more information about fungibles traits.
 
-use sp_runtime::{DispatchError, DispatchResult};
-
 use super::Inspect;
+use crate::traits::tokens::{AssetId, Balance};
+use sp_runtime::{DispatchError, DispatchResult};
 
 /// Trait for providing the ability to create new fungible assets.
 pub trait Create<AccountId>: Inspect<AccountId> {
@@ -34,6 +34,22 @@ pub trait Create<AccountId>: Inspect<AccountId> {
 	) -> DispatchResult;
 }
 
+/// Trait for refunding the existence deposit of a target asset account.
+///
+/// The existence deposit might by necessary and present in cases where the asset held by the
+/// account is insufficient for the required storage, or when the system cannot provide a consumer
+/// reference for any reason.
+pub trait Refund<AccountId> {
+	/// Means of identifying one asset class from another.
+	type AssetId: AssetId;
+	/// Scalar type for representing deposit balance of an account.
+	type Balance: Balance;
+	/// Returns the amount of account deposit and depositor address, if any.
+	fn deposit_held(id: Self::AssetId, who: AccountId) -> Option<(AccountId, Self::Balance)>;
+	/// Return the deposit (if any) of a target asset account.
+	fn refund(id: Self::AssetId, who: AccountId) -> DispatchResult;
+}
+
 /// Trait for providing the ability to destroy existing fungible assets.
 pub trait Destroy<AccountId>: Inspect<AccountId> {
 	/// Start the destruction an existing fungible asset.

substrate/frame/support/src/traits/tokens/fungibles/mod.rs

@@ -44,7 +44,7 @@ pub use hold::{
 	Unbalanced as UnbalancedHold,
 };
 pub use imbalance::{Credit, Debt, HandleImbalanceDrop, Imbalance};
-pub use lifetime::{Create, Destroy};
+pub use lifetime::{Create, Destroy, Refund};
 pub use regular::{
 	Balanced, DecreaseIssuance, Dust, IncreaseIssuance, Inspect, Mutate, Unbalanced,
 };

substrate/frame/support/src/traits/tokens/fungibles/roles.rs

@@ -19,6 +19,8 @@
 //!
 //! See the [`crate::traits::fungibles`] doc for more information about fungibles traits.
 
+use sp_runtime::DispatchResult;
+
 pub trait Inspect<AccountId>: super::Inspect<AccountId> {
 	// Get owner for an AssetId.
 	fn owner(asset: Self::AssetId) -> Option<AccountId>;
@@ -29,3 +31,22 @@ pub trait Inspect<AccountId>: super::Inspect<AccountId> {
 	// Get freezer for an AssetId.
 	fn freezer(asset: Self::AssetId) -> Option<AccountId>;
 }
+
+/// Trait for resetting the team configuration of an existing fungible asset.
+pub trait ResetTeam<AccountId>: super::Inspect<AccountId> {
+	/// Reset the team for the asset with the given `id`.
+	///
+	/// ### Parameters
+	/// - `id`: The identifier of the asset for which the team is being reset.
+	/// - `owner`: The new `owner` account for the asset.
+	/// - `admin`: The new `admin` account for the asset.
+	/// - `issuer`: The new `issuer` account for the asset.
+	/// - `freezer`: The new `freezer` account for the asset.
+	fn reset_team(
+		id: Self::AssetId,
+		owner: AccountId,
+		admin: AccountId,
+		issuer: AccountId,
+		freezer: AccountId,
+	) -> DispatchResult;
+}

substrate/frame/support/src/traits/tokens/fungibles/union_of.rs

@@ -904,3 +904,35 @@ impl<
 		}
 	}
 }
+
+impl<
+		Left: fungibles::Inspect<AccountId> + fungibles::Refund<AccountId>,
+		Right: fungibles::Inspect<AccountId>
+			+ fungibles::Refund<AccountId, Balance = <Left as fungibles::Refund<AccountId>>::Balance>,
+		Criterion: Convert<
+			AssetKind,
+			Either<
+				<Left as fungibles::Refund<AccountId>>::AssetId,
+				<Right as fungibles::Refund<AccountId>>::AssetId,
+			>,
+		>,
+		AssetKind: AssetId,
+		AccountId,
+	> fungibles::Refund<AccountId> for UnionOf<Left, Right, Criterion, AssetKind, AccountId>
+{
+	type AssetId = AssetKind;
+	type Balance = <Left as fungibles::Refund<AccountId>>::Balance;
+
+	fn deposit_held(asset: AssetKind, who: AccountId) -> Option<(AccountId, Self::Balance)> {
+		match Criterion::convert(asset) {
+			Left(a) => <Left as fungibles::Refund<AccountId>>::deposit_held(a, who),
+			Right(a) => <Right as fungibles::Refund<AccountId>>::deposit_held(a, who),
+		}
+	}
+	fn refund(asset: AssetKind, who: AccountId) -> DispatchResult {
+		match Criterion::convert(asset) {
+			Left(a) => <Left as fungibles::Refund<AccountId>>::refund(a, who),
+			Right(a) => <Right as fungibles::Refund<AccountId>>::refund(a, who),
+		}
+	}
+}