[Coretime] Always include UnpaidExecution, not just when revenue is >…

… 0 (#5369)

The NotifyRevenue XCM from relay to coretime chain fails to pass the
barrier when revenue is 0.


https://github.com/paritytech/polkadot-sdk/blob/master/polkadot/runtime/parachains/src/coretime/mod.rs#L401
pushes notifyrevenue onto an [empty
vec](https://github.com/paritytech/polkadot-sdk/blob/master/polkadot/runtime/parachains/src/coretime/mod.rs#L361)
when `revenue == 0`, so it never explicitly requests unpaid execution,
because that happens only in [the block where revenue is `>
0`](https://github.com/paritytech/polkadot-sdk/blob/master/polkadot/runtime/parachains/src/coretime/mod.rs#L387).

This will need to be backported to 1.14 when merged.

polkadot/runtime/parachains/src/coretime/mod.rs

@@ -358,7 +358,10 @@ fn mk_coretime_call<T: Config>(call: crate::coretime::CoretimeCalls) -> Instruct
 
 fn do_notify_revenue<T: Config>(when: BlockNumber, raw_revenue: Balance) -> Result<(), XcmError> {
  let dest = Junction::Parachain(T::BrokerId::get()).into_location();
- let mut message = Vec::new();
+ let mut message = vec![Instruction::UnpaidExecution {
+ weight_limit: WeightLimit::Unlimited,
+ check_origin: None,
+ }];
  let asset = Asset { id: AssetId(Location::here()), fun: Fungible(raw_revenue) };
  let dummy_xcm_context = XcmContext { origin: None, message_id: [0; 32], topic: None };
 
@@ -384,10 +387,6 @@ fn do_notify_revenue<T: Config>(when: BlockNumber, raw_revenue: Balance) -> Resu
 
  message.extend(
  [
- Instruction::UnpaidExecution {
- weight_limit: WeightLimit::Unlimited,
- check_origin: None,
- },
  ReceiveTeleportedAsset(assets_reanchored),
  DepositAsset {
  assets: Wild(AllCounted(1)),

prdoc/pr_5369.prdoc

@@ -0,0 +1,15 @@
+# Schema: Polkadot SDK PRDoc Schema (prdoc) v1.0.0
+# See doc at https://raw.githubusercontent.com/paritytech/polkadot-sdk/master/prdoc/schema_user.json
+
+title: Fix failing XCM from relay to Coretime Chain when revenue is zero
+
+doc:
+ - audience: Runtime Dev
+ description: |
+ The coretime assigner now always includes UnpaidExecution when calling `notify_revenue` via a
+ `Transact`, not just when revenue is nonzero. This fixes an issue where the XCM would fail to
+ process on the receiving side.
+
+crates:
+ - name: polkadot-runtime-parachains
+ bump: patch