treasury: redirect burns to DAP

Author: sigurpol

Cargo.lock

@@ -131,7 +131,7 @@ impl pallet_treasury::Config for Runtime {
 	type RuntimeEvent = RuntimeEvent;
 	type SpendPeriod = SpendPeriod;
 	type Burn = Burn;
-	type BurnDestination = ();
+	type BurnDestination = pallet_dap::BurnToDap<Runtime, Balances>;
 	type MaxApprovals = MaxApprovals;
 	type WeightInfo = weights::pallet_treasury::WeightInfo<Runtime>;
 	type SpendFunds = ();

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

@@ -34,7 +34,7 @@ use frame_support::{
 	traits::{
 		fungible::{Balanced, Credit, Inspect, Mutate},
 		tokens::{FundingSink, FundingSource, Preservation},
-		Imbalance, OnUnbalanced,
+		Currency, Imbalance, OnUnbalanced,
 	},
 	PalletId,
 };
@@ -122,10 +122,11 @@ impl<T: Config> FundingSink<T::AccountId, BalanceOf<T>> for ReturnToDap<T> {
 }
 
 /// Type alias for credit (negative imbalance - funds that were slashed/removed).
+/// This is for the `fungible::Balanced` trait as used by staking-async.
 pub type CreditOf<T> = Credit<<T as frame_system::Config>::AccountId, <T as Config>::Currency>;
 
-/// Implementation of OnUnbalanced that deposits slashed funds into the DAP buffer.
-/// Use this as `type Slash = SlashToDap<Runtime>` in staking config.
+/// Implementation of OnUnbalanced for the fungible::Balanced trait.
+/// Use this as `type Slash = SlashToDap<Runtime>` in staking-async config.
 pub struct SlashToDap<T>(core::marker::PhantomData<T>);
 
 impl<T: Config> OnUnbalanced<CreditOf<T>> for SlashToDap<T> {
@@ -143,6 +144,29 @@ impl<T: Config> OnUnbalanced<CreditOf<T>> for SlashToDap<T> {
 	}
 }
 
+/// Implementation of OnUnbalanced for the old Currency trait (still used by treasury).
+/// Use this as `type BurnDestination = BurnToDap<Runtime, Balances>` e.g. in treasury config.
+pub struct BurnToDap<T, C>(core::marker::PhantomData<(T, C)>);
+
+impl<T, C> OnUnbalanced<C::NegativeImbalance> for BurnToDap<T, C>
+where
+	T: Config,
+	C: Currency<T::AccountId>,
+{
+	fn on_nonzero_unbalanced(amount: C::NegativeImbalance) {
+		let buffer = Pallet::<T>::buffer_account();
+		let numeric_amount = amount.peek();
+
+		// Resolve the imbalance by depositing into the buffer account
+		C::resolve_creating(&buffer, amount);
+
+		log::debug!(
+			target: LOG_TARGET,
+			"Deposited burn of {numeric_amount:?} to DAP buffer"
+		);
+	}
+}
+
 #[cfg(test)]
 mod tests {
 	use super::*;

substrate/frame/dap/src/lib.rs

@@ -118,6 +118,7 @@ cumulus-primitives-aura = { workspace = true }
 cumulus-primitives-core = { workspace = true }
 cumulus-primitives-utility = { workspace = true }
 pallet-collator-selection = { workspace = true }
+pallet-dap = { workspace = true }
 pallet-message-queue = { workspace = true }
 parachain-info = { workspace = true }
 parachains-common = { workspace = true }
@@ -169,6 +170,7 @@ runtime-benchmarks = [
 	"pallet-balances/runtime-benchmarks",
 	"pallet-collator-selection/runtime-benchmarks",
 	"pallet-conviction-voting/runtime-benchmarks",
+	"pallet-dap/runtime-benchmarks",
 	"pallet-delegated-staking/runtime-benchmarks",
 	"pallet-election-provider-multi-block/runtime-benchmarks",
 	"pallet-fast-unstake/runtime-benchmarks",
@@ -234,6 +236,7 @@ try-runtime = [
 	"pallet-balances/try-runtime",
 	"pallet-collator-selection/try-runtime",
 	"pallet-conviction-voting/try-runtime",
+	"pallet-dap/try-runtime",
 	"pallet-delegated-staking/try-runtime",
 	"pallet-election-provider-multi-block/try-runtime",
 	"pallet-fast-unstake/try-runtime",
@@ -305,6 +308,7 @@ std = [
 	"pallet-balances/std",
 	"pallet-collator-selection/std",
 	"pallet-conviction-voting/std",
+	"pallet-dap/std",
 	"pallet-delegated-staking/std",
 	"pallet-election-provider-multi-block/std",
 	"pallet-fast-unstake/std",

substrate/frame/staking-async/runtimes/parachain/Cargo.toml

@@ -138,7 +138,7 @@ impl pallet_treasury::Config for Runtime {
 	type RuntimeEvent = RuntimeEvent;
 	type SpendPeriod = SpendPeriod;
 	type Burn = Burn;
-	type BurnDestination = ();
+	type BurnDestination = pallet_dap::BurnToDap<Runtime, Balances>;
 	type MaxApprovals = MaxApprovals;
 	type WeightInfo = weights::pallet_treasury::WeightInfo<Runtime>;
 	type SpendFunds = ();

substrate/frame/staking-async/runtimes/parachain/src/governance/mod.rs

@@ -1196,6 +1196,9 @@ construct_runtime!(
 		Treasury: pallet_treasury = 96,
 		AssetRate: pallet_asset_rate = 97,
 
+		// Dynamic Allocation Pool / Issuance buffer
+		Dap: pallet_dap = 98,
+
 		// Balances.
 		Vesting: pallet_vesting = 100,
 

substrate/frame/staking-async/runtimes/parachain/src/lib.rs

@@ -432,7 +432,7 @@ impl pallet_staking_async::Config for Runtime {
 	type RuntimeHoldReason = RuntimeHoldReason;
 	type CurrencyToVote = sp_staking::currency_to_vote::SaturatingCurrencyToVote;
 	type RewardRemainder = ();
-	type Slash = ();
+	type Slash = pallet_dap::SlashToDap<Runtime>;
 	type Reward = ();
 	type SessionsPerEra = SessionsPerEra;
 	type BondingDuration = BondingDuration;
@@ -464,6 +464,10 @@ impl pallet_staking_async_rc_client::Config for Runtime {
 	type MaxValidatorSetRetries = ConstU32<5>;
 }
 
+impl pallet_dap::Config for Runtime {
+	type Currency = Balances;
+}
+
 parameter_types! {
 	pub StakingXcmDestination: Location = Location::parent();
 }