Add migration to clear unapproved proposals from treasury pallet

cumulus/parachains/runtimes/collectives/collectives-westend/src/lib.rs

@@ -757,6 +757,8 @@ type Migrations = (
 	pallet_core_fellowship::migration::MigrateV0ToV1<Runtime, FellowshipCoreInstance>,
 	// unreleased
 	pallet_core_fellowship::migration::MigrateV0ToV1<Runtime, AmbassadorCoreInstance>,
+	// unreleased
+	pallet_treasury::migration::MigrateV0ToV1<Runtime, FellowshipCoreInstance>,
 );
 
 /// Executive: handles dispatch to the various modules.

polkadot/runtime/rococo/src/lib.rs

@@ -1677,6 +1677,9 @@ pub mod migrations {
         // permanent
         pallet_xcm::migration::MigrateToLatestXcmVersion<Runtime>,
         parachains_inclusion::migration::MigrateToV1<Runtime>,
+
+        // Release bonds stuck in proposals
+        pallet_treasury::migration::MigrateV0ToV1<Runtime, ()>,
     );
 }
 

prdoc/pr_5892.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: Add migration to clear unapproved proposals treasury from pallet
+
+doc:
+  - audience: Runtime Dev
+    description: |
+      It is no longer possible to create Proposals in this pallet but there
+      are some Proposals whose bonds are stuck.  Purpose of this migration is to
+      clear those and return bonds to the proposers.
+
+crates:
+    - name: pallet-treasury
+      bump: patch

substrate/frame/treasury/Cargo.toml

@@ -30,6 +30,7 @@ frame-system = { workspace = true }
 pallet-balances = { workspace = true }
 sp-runtime = { workspace = true }
 sp-core = { optional = true, workspace = true }
+log = { workspace = true }
 
 [dev-dependencies]
 sp-io = { workspace = true, default-features = true }

substrate/frame/treasury/src/lib.rs

@@ -73,6 +73,7 @@
 #![cfg_attr(not(feature = "std"), no_std)]
 
 mod benchmarking;
+pub mod migration;
 #[cfg(test)]
 mod tests;
 pub mod weights;
@@ -199,7 +200,10 @@ pub mod pallet {
 	};
 	use frame_system::pallet_prelude::*;
 
+	const STORAGE_VERSION: StorageVersion = StorageVersion::new(1);
+
 	#[pallet::pallet]
+	#[pallet::storage_version(STORAGE_VERSION)]
 	pub struct Pallet<T, I = ()>(PhantomData<(T, I)>);
 
 	#[pallet::config]

substrate/frame/treasury/src/migration.rs

@@ -0,0 +1,74 @@
+use super::*;
+use alloc::collections::BTreeSet;
+use core::marker::PhantomData;
+use frame_support::traits::UncheckedOnRuntimeUpgrade;
+
+/// The log target for this pallet.
+const LOG_TARGET: &str = "runtime::treasury";
+
+mod v1 {
+	use super::*;
+	pub struct MigrateToV1Impl<T, I>(PhantomData<(T, I)>);
+
+	impl<T: Config<I>, I: 'static> UncheckedOnRuntimeUpgrade for MigrateToV1Impl<T, I> {
+		fn on_runtime_upgrade() -> frame_support::weights::Weight {
+			let mut approval_index = BTreeSet::new();
+			for approval in Approvals::<T, I>::get().iter() {
+				approval_index.insert(*approval);
+			}
+
+			let mut proposals_released = 0;
+			for (proposal_index, p) in Proposals::<T, I>::iter() {
+				if !approval_index.contains(&proposal_index) {
+					let err_amount = T::Currency::unreserve(&p.proposer, p.bond);
+					debug_assert!(err_amount.is_zero());
+					Proposals::<T, I>::remove(proposal_index);
+					log::info!(
+						target: LOG_TARGET,
+						"Released bond amount of {:?} to proposer {:?}",
+						p.bond,
+						p.proposer,
+					);
+					proposals_released += 1;
+				}
+			}
+
+			log::info!(
+				target: LOG_TARGET,
+				"Storage migration v1 for pallet-treasury finished, released {} proposal bonds.",
+				proposals_released,
+			);
+
+			// calculate and return migration weights
+			let approvals_read = 1;
+			T::DbWeight::get()
+				.reads_writes(proposals_released as u64 + approvals_read, proposals_released as u64)
+		}
+
+		#[cfg(feature = "try-runtime")]
+		fn pre_upgrade() -> Result<Vec<u8>, sp_runtime::TryRuntimeError> {
+			Ok((Proposals::<T, I>::iter_values().count() as u32).encode())
+		}
+
+		#[cfg(feature = "try-runtime")]
+		fn post_upgrade(state: Vec<u8>) -> Result<(), sp_runtime::TryRuntimeError> {
+			let old_count = u32::decode(&mut &state[..]).expect("Known good");
+			let new_count = Proposals::<T, I>::iter_values().count() as u32;
+
+			ensure!(
+				old_count <= new_count,
+				"Proposals after migration should be less or equal to old proposals"
+			);
+			Ok(())
+		}
+	}
+}
+
+/// Migrate the pallet storage from `0` to `1`.
+pub type MigrateV0ToV1<T, I> = frame_support::migrations::VersionedMigration<
+	0,
+	1,
+	v1::MigrateToV1Impl<T, I>,
+	Pallet<T, I>,
+	<T as frame_system::Config>::DbWeight,
+>;