Use #[pallet::storage_version] for pallet staking (#12728)

* delete releases

* use standard pallet storage version

* migrate to standard storage version for staking

* not compiling

* keep old releases enum around for decoding

* fix releases

* rename old releases

* retriggering ci

* fix migration comments

* doc update

Co-authored-by: parity-processbot <>

substrate/frame/staking/src/lib.rs

@@ -881,31 +881,6 @@ impl Default for Forcing {
 	}
 }
 
-// A value placed in storage that represents the current version of the Staking storage. This value
-// is used by the `on_runtime_upgrade` logic to determine whether we run storage migration logic.
-// This should match directly with the semantic versions of the Rust crate.
-#[derive(Encode, Decode, Clone, Copy, PartialEq, Eq, RuntimeDebug, TypeInfo, MaxEncodedLen)]
-enum Releases {
-	V1_0_0Ancient,
-	V2_0_0,
-	V3_0_0,
-	V4_0_0,
-	V5_0_0,  // blockable validators.
-	V6_0_0,  // removal of all storage associated with offchain phragmen.
-	V7_0_0,  // keep track of number of nominators / validators in map
-	V8_0_0,  // populate `VoterList`.
-	V9_0_0,  // inject validators into `VoterList` as well.
-	V10_0_0, // remove `EarliestUnappliedSlash`.
-	V11_0_0, // Move pallet storage prefix, e.g. BagsList -> VoterBagsList
-	V12_0_0, // remove `HistoryDepth`.
-}
-
-impl Default for Releases {
-	fn default() -> Self {
-		Releases::V11_0_0
-	}
-}
-
 /// A `Convert` implementation that finds the stash of the given controller account,
 /// if any.
 pub struct StashOf<T>(sp_std::marker::PhantomData<T>);