fix(pallet-multi-asset-bounties): use non-destructive read in calculate_payout()

prdoc/pr_11425.prdoc

@@ -0,0 +1,12 @@
+title: 'fix(pallet-multi-asset-bounties): use non-destructive read in calculate_payout()'
+doc:
+- audience: Runtime Dev
+  description: |
+    Fix `calculate_payout()` using `ChildBountiesValuePerParent::take()` instead of `get()`.
+    The destructive `take()` deletes the storage entry on first call, causing
+    `BountyPayoutProcessed` to emit an incorrect payout value when `check_status()` calls
+    `calculate_payout()` a second time on the success path. Replaced `take()` with `get()`
+    and moved storage cleanup to `remove_bounty()`.
+crates:
+- name: pallet-multi-asset-bounties
+  bump: patch

substrate/frame/multi-asset-bounties/src/lib.rs

@@ -96,7 +96,7 @@ use frame_system::pallet_prelude::{
 };
 use scale_info::TypeInfo;
 use sp_runtime::{
-	traits::{AccountIdConversion, BadOrigin, Convert, Saturating, StaticLookup, TryConvert, Zero},
+	traits::{AccountIdConversion, BadOrigin, Convert, Saturating, StaticLookup, TryConvert},
 	Debug, Permill,
 };
 
@@ -1551,7 +1551,7 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 			None => {
 				// Get total child bounties value, and subtract it from the parent
 				// value.
-				let children_value = ChildBountiesValuePerParent::<T, I>::take(parent_bounty_id);
+				let children_value = ChildBountiesValuePerParent::<T, I>::get(parent_bounty_id);
 				debug_assert!(children_value <= value);
 				let payout = value.saturating_sub(children_value);
 				payout
@@ -1571,7 +1571,7 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 				Bounties::<T, I>::remove(parent_bounty_id);
 				ChildBountiesPerParent::<T, I>::remove(parent_bounty_id);
 				TotalChildBountiesPerParent::<T, I>::remove(parent_bounty_id);
-				debug_assert!(ChildBountiesValuePerParent::<T, I>::get(parent_bounty_id).is_zero());
+				ChildBountiesValuePerParent::<T, I>::remove(parent_bounty_id);
 			},
 			Some(child_bounty_id) => {
 				ChildBounties::<T, I>::remove(parent_bounty_id, child_bounty_id);

substrate/frame/multi-asset-bounties/src/tests.rs

@@ -947,7 +947,16 @@ fn check_status_works() {
 		set_status(payment_id, PaymentStatus::Success);
 		assert_ok!(Bounties::check_status(RuntimeOrigin::signed(1), s.parent_bounty_id, None));
 
-		// Then
+		// Then: BountyPayoutProcessed should emit the net payout (parent value minus child
+		// value), not the full parent value.
+		let expected_payout = s.value - s.child_value;
+		expect_events(vec![BountiesEvent::BountyPayoutProcessed {
+			index: s.parent_bounty_id,
+			child_index: None,
+			asset_kind: s.asset_kind,
+			value: expected_payout,
+			beneficiary: s.beneficiary,
+		}]);
 		assert_eq!(
 			pallet_bounties::ChildBountiesValuePerParent::<Test>::get(s.parent_bounty_id),
 			0