fix migrations (also companion for #14421) (#7454)

* fix migrations

* use society versioned runtime upgrade

* simplify usage of versionedruntimeupgrade

* use society experimental feature

* improve usage of experimental flag

* doc comment

* Merge branch 'master' of github.com:paritytech/polkadot into liam-fix-migrations

* Revert "Merge branch 'master' of github.com:paritytech/polkadot into liam-fix-migrations"

This reverts commit 41ab0621811ead11b0a7f91338b0895208feef77.

* doc comment

* westend experimental feature

* Revert "westend experimental feature"

This reverts commit 42f4f1b76655ef509a92c324d18d635a1b913dcb.

* feature gate experimental xcm migration

* update lockfile for {"substrate"}

---------

Co-authored-by: parity-processbot <>

polkadot/xcm/pallet-xcm/Cargo.toml

@@ -31,6 +31,10 @@ xcm-builder = { path = "../xcm-builder" }
 
 [features]
 default = ["std"]
+# Enable `VersionedRuntimeUpgrade` for the migrations that is currently still experimental.
+experimental = [
+	"frame-support/experimental"
+]
 std = [
 	"bounded-collections/std",
 	"codec/std",

polkadot/xcm/pallet-xcm/src/migration.rs

@@ -26,8 +26,13 @@ const DEFAULT_PROOF_SIZE: u64 = 64 * 1024;
 pub mod v1 {
 	use super::*;
 
-	pub struct MigrateToV1<T>(sp_std::marker::PhantomData<T>);
-	impl<T: Config> OnRuntimeUpgrade for MigrateToV1<T> {
+	/// Named with the 'VersionUnchecked'-prefix because although this implements some version
+	/// checking, the version checking is not complete as it will begin failing after the upgrade is
+	/// enacted on-chain.
+	///
+	/// Use experimental [`VersionCheckedMigrateToV1`] instead.
+	pub struct VersionUncheckedMigrateToV1<T>(sp_std::marker::PhantomData<T>);
+	impl<T: Config> OnRuntimeUpgrade for VersionUncheckedMigrateToV1<T> {
 		#[cfg(feature = "try-runtime")]
 		fn pre_upgrade() -> Result<sp_std::vec::Vec<u8>, sp_runtime::TryRuntimeError> {
 			ensure!(StorageVersion::get::<Pallet<T>>() == 0, "must upgrade linearly");
@@ -58,4 +63,17 @@ pub mod v1 {
 			}
 		}
 	}
+
+	/// Version checked migration to v1.
+	///
+	/// Wrapped in VersionedRuntimeUpgrade so the pre/post checks don't begin failing after the
+	/// upgrade is enacted on-chain.
+	#[cfg(feature = "experimental")]
+	pub type VersionCheckedMigrateToV1<T> = frame_support::migrations::VersionedRuntimeUpgrade<
+		0,
+		1,
+		VersionUncheckedMigrateToV1<T>,
+		crate::pallet::Pallet<T>,
+		<T as frame_system::Config>::DbWeight,
+	>;
 }