From a1fa4e3e9e4781ce14c8c917dc3e872e690f756b Mon Sep 17 00:00:00 2001
From: likhita-809 <likhita@vitwit.com>
Date: Tue, 22 Aug 2023 13:35:27 +0530
Subject: [PATCH 01/13] wip: migrate LastValidatorPower to collections

---
 x/staking/keeper/keeper.go            |  4 +++-
 x/staking/keeper/validator.go         | 20 ++++++++++++++------
 x/staking/keeper/validator_test.go    |  2 ++
 x/staking/migrations/v2/store_test.go |  7 ++++++-
 x/staking/types/keys.go               | 10 +++++-----
 5 files changed, 30 insertions(+), 13 deletions(-)

diff --git a/x/staking/keeper/keeper.go b/x/staking/keeper/keeper.go
index a2d8f6ff3985..0d40c8491cf5 100644
--- a/x/staking/keeper/keeper.go
+++ b/x/staking/keeper/keeper.go
@@ -44,6 +44,7 @@ type Keeper struct {
 	Redelegations               collections.Map[collections.Triple[[]byte, []byte, []byte], types.Redelegation]
 	Delegations                 collections.Map[collections.Pair[sdk.AccAddress, sdk.ValAddress], types.Delegation]
 	UnbondingIndex              collections.Map[uint64, []byte]
+	LastValidatorPower          collections.Map[sdk.ValAddress, []byte]
 }
 
 // NewKeeper creates a new staking Keeper instance
@@ -119,7 +120,8 @@ func NewKeeper(
 			),
 			codec.CollValue[types.Redelegation](cdc),
 		),
-		UnbondingIndex: collections.NewMap(sb, types.UnbondingIndexKey, "unbonding_index", collections.Uint64Key, collections.BytesValue),
+		UnbondingIndex:     collections.NewMap(sb, types.UnbondingIndexKey, "unbonding_index", collections.Uint64Key, collections.BytesValue),
+		LastValidatorPower: collections.NewMap(sb, types.LastValidatorPowerKey, "last_validator_power", sdk.LengthPrefixedAddressKey(sdk.ValAddressKey), collections.BytesValue), // nolint: staticcheck // sdk.LengthPrefixedAddressKey is needed to retain state compatibility
 	}
 
 	schema, err := sb.Build()
diff --git a/x/staking/keeper/validator.go b/x/staking/keeper/validator.go
index 1462b3e9a6fc..dd7b6c7751cf 100644
--- a/x/staking/keeper/validator.go
+++ b/x/staking/keeper/validator.go
@@ -342,8 +342,9 @@ func (k Keeper) ValidatorsPowerStoreIterator(ctx context.Context) (corestore.Ite
 // GetLastValidatorPower loads the last validator power.
 // Returns zero if the operator was not a validator last block.
 func (k Keeper) GetLastValidatorPower(ctx context.Context, operator sdk.ValAddress) (power int64, err error) {
-	store := k.storeService.OpenKVStore(ctx)
-	bz, err := store.Get(types.GetLastValidatorPowerKey(operator))
+	// store := k.storeService.OpenKVStore(ctx)
+	// bz, err := store.Get(types.GetLastValidatorPowerKey(operator))
+	bz, err := k.LastValidatorPower.Get(ctx, operator)
 	if err != nil {
 		return 0, err
 	}
@@ -363,18 +364,25 @@ func (k Keeper) GetLastValidatorPower(ctx context.Context, operator sdk.ValAddre
 
 // SetLastValidatorPower sets the last validator power.
 func (k Keeper) SetLastValidatorPower(ctx context.Context, operator sdk.ValAddress, power int64) error {
-	store := k.storeService.OpenKVStore(ctx)
+	// store := k.storeService.OpenKVStore(ctx)
 	bz, err := k.cdc.Marshal(&gogotypes.Int64Value{Value: power})
 	if err != nil {
 		return err
 	}
-	return store.Set(types.GetLastValidatorPowerKey(operator), bz)
+	// return store.Set(types.GetLastValidatorPowerKey(operator), bz)
+	return k.LastValidatorPower.Set(ctx, operator, bz)
 }
 
 // DeleteLastValidatorPower deletes the last validator power.
 func (k Keeper) DeleteLastValidatorPower(ctx context.Context, operator sdk.ValAddress) error {
-	store := k.storeService.OpenKVStore(ctx)
-	return store.Delete(types.GetLastValidatorPowerKey(operator))
+	// store := k.storeService.OpenKVStore(ctx)
+	// return store.Delete(types.GetLastValidatorPowerKey(operator))
+	bz, err := k.cdc.Marshal(&gogotypes.Int64Value{Value: 0})
+	if err != nil {
+		return err
+	}
+	return k.LastValidatorPower.Set(ctx, operator, bz)
+	// return k.LastValidatorPower.Remove(ctx, operator)
 }
 
 // lastValidatorsIterator returns an iterator for the consensus validators in the last block
diff --git a/x/staking/keeper/validator_test.go b/x/staking/keeper/validator_test.go
index f5015f7844a2..1e95acb6f251 100644
--- a/x/staking/keeper/validator_test.go
+++ b/x/staking/keeper/validator_test.go
@@ -1,6 +1,7 @@
 package keeper_test
 
 import (
+	"fmt"
 	"time"
 
 	abci "github.com/cometbft/cometbft/abci/types"
@@ -77,6 +78,7 @@ func (s *KeeperTestSuite) TestValidator() {
 	// check the last validator power
 	power := int64(100)
 	require.NoError(keeper.SetLastValidatorPower(ctx, valAddr, power))
+	fmt.Printf("valAddr: %v\n", valAddr.String())
 	resPower, err := keeper.GetLastValidatorPower(ctx, valAddr)
 	require.NoError(err)
 	require.Equal(power, resPower)
diff --git a/x/staking/migrations/v2/store_test.go b/x/staking/migrations/v2/store_test.go
index 7e8750877d0d..86ff7647b3c7 100644
--- a/x/staking/migrations/v2/store_test.go
+++ b/x/staking/migrations/v2/store_test.go
@@ -13,6 +13,7 @@ import (
 	sdktestuil "github.com/cosmos/cosmos-sdk/testutil"
 	"github.com/cosmos/cosmos-sdk/testutil/testdata"
 	sdk "github.com/cosmos/cosmos-sdk/types"
+	sdkaddress "github.com/cosmos/cosmos-sdk/types/address"
 	v1 "github.com/cosmos/cosmos-sdk/x/staking/migrations/v1"
 	v2 "github.com/cosmos/cosmos-sdk/x/staking/migrations/v2"
 	"github.com/cosmos/cosmos-sdk/x/staking/testutil"
@@ -45,7 +46,7 @@ func TestStoreMigration(t *testing.T) {
 		{
 			"LastValidatorPowerKey",
 			v1.GetLastValidatorPowerKey(valAddr1),
-			types.GetLastValidatorPowerKey(valAddr1),
+			getLastValidatorPowerKey(valAddr1),
 		},
 		{
 			"LastTotalPowerKey",
@@ -139,3 +140,7 @@ func TestStoreMigration(t *testing.T) {
 		})
 	}
 }
+
+func getLastValidatorPowerKey(operator sdk.ValAddress) []byte {
+	return append(types.LastValidatorPowerKey, sdkaddress.MustLengthPrefix(operator)...)
+}
diff --git a/x/staking/types/keys.go b/x/staking/types/keys.go
index 961f9b33f3da..084855b797a5 100644
--- a/x/staking/types/keys.go
+++ b/x/staking/types/keys.go
@@ -32,7 +32,7 @@ const (
 var (
 	// Keys for store prefixes
 	// Last* values are constant during a block.
-	LastValidatorPowerKey = []byte{0x11}              // prefix for each key to a validator index, for bonded validators
+	LastValidatorPowerKey = collections.NewPrefix(17) // prefix for each key to a validator index, for bonded validators
 	LastTotalPowerKey     = collections.NewPrefix(18) // prefix for the total power
 
 	ValidatorsKey             = []byte{0x21}              // prefix for each key to a validator
@@ -127,10 +127,10 @@ func GetValidatorsByPowerIndexKey(validator Validator, powerReduction math.Int,
 	return key
 }
 
-// GetLastValidatorPowerKey creates the bonded validator index key for an operator address
-func GetLastValidatorPowerKey(operator sdk.ValAddress) []byte {
-	return append(LastValidatorPowerKey, address.MustLengthPrefix(operator)...)
-}
+// // GetLastValidatorPowerKey creates the bonded validator index key for an operator address
+// func GetLastValidatorPowerKey(operator sdk.ValAddress) []byte {
+// 	return append(LastValidatorPowerKey, address.MustLengthPrefix(operator)...)
+// }
 
 // ParseValidatorPowerRankKey parses the validators operator address from power rank key
 func ParseValidatorPowerRankKey(key []byte) (operAddr []byte) {

From 0d3368bdfaef9d38908dbcb8761259bb7c642a12 Mon Sep 17 00:00:00 2001
From: likhita-809 <likhita@vitwit.com>
Date: Tue, 22 Aug 2023 13:51:44 +0530
Subject: [PATCH 02/13] add diff tests

---
 x/staking/keeper/keeper_test.go | 42 +++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/x/staking/keeper/keeper_test.go b/x/staking/keeper/keeper_test.go
index f12a55fc04e4..a1ce85a788bf 100644
--- a/x/staking/keeper/keeper_test.go
+++ b/x/staking/keeper/keeper_test.go
@@ -12,7 +12,10 @@ import (
 	"cosmossdk.io/math"
 	storetypes "cosmossdk.io/store/types"
 
+	gogotypes "github.com/cosmos/gogoproto/types"
+
 	"github.com/cosmos/cosmos-sdk/baseapp"
+	"github.com/cosmos/cosmos-sdk/codec"
 	"github.com/cosmos/cosmos-sdk/codec/address"
 	"github.com/cosmos/cosmos-sdk/runtime"
 	"github.com/cosmos/cosmos-sdk/testutil"
@@ -42,6 +45,7 @@ type KeeperTestSuite struct {
 	queryClient   stakingtypes.QueryClient
 	msgServer     stakingtypes.MsgServer
 	key           *storetypes.KVStoreKey
+	cdc           codec.Codec
 }
 
 func (s *KeeperTestSuite) SetupTest() {
@@ -52,6 +56,7 @@ func (s *KeeperTestSuite) SetupTest() {
 	s.key = key
 	ctx := testCtx.Ctx.WithBlockHeader(cmtproto.Header{Time: cmttime.Now()})
 	encCfg := moduletestutil.MakeTestEncodingConfig()
+	s.cdc = encCfg.Codec
 
 	ctrl := gomock.NewController(s.T())
 	accountKeeper := stakingtestutil.NewMockAccountKeeper(ctrl)
@@ -137,6 +142,43 @@ func getREDsFromValSrcIndexKey(valSrcAddr sdk.ValAddress) []byte {
 	return append(redelegationByValSrcIndexKey, addresstypes.MustLengthPrefix(valSrcAddr)...)
 }
 
+func getLastValidatorPowerKey(operator sdk.ValAddress) []byte {
+	lastValidatorPowerKey := []byte{0x11}
+	return append(lastValidatorPowerKey, addresstypes.MustLengthPrefix(operator)...)
+}
+
+func (s *KeeperTestSuite) TestLastTotalPowerMigrationToColls() {
+	s.SetupTest()
+
+	_, valAddrs := createValAddrs(101)
+
+	bz, err := s.cdc.Marshal(&gogotypes.Int64Value{Value: 1})
+	s.Require().NoError(err)
+
+	err = testutil.DiffCollectionsMigration(
+		s.ctx,
+		s.key,
+		100,
+		func(i int64) {
+			s.ctx.KVStore(s.key).Set(getLastValidatorPowerKey(valAddrs[i]), bz)
+		},
+		"6cd9b908445fbe0b280b82cac51758cdb125882674a91d348b690dac4b7055cb",
+	)
+	s.Require().NoError(err)
+
+	err = testutil.DiffCollectionsMigration(
+		s.ctx,
+		s.key,
+		100,
+		func(i int64) {
+			err := s.stakingKeeper.LastValidatorPower.Set(s.ctx, valAddrs[i], bz)
+			s.Require().NoError(err)
+		},
+		"6cd9b908445fbe0b280b82cac51758cdb125882674a91d348b690dac4b7055cb",
+	)
+	s.Require().NoError(err)
+}
+
 func (s *KeeperTestSuite) TestRedelegationsMigrationToColls() {
 	s.SetupTest()
 

From 29fcab0977c664e991d9df4ae123c6b4048653f8 Mon Sep 17 00:00:00 2001
From: likhita-809 <likhita@vitwit.com>
Date: Tue, 22 Aug 2023 14:30:09 +0530
Subject: [PATCH 03/13] remove commented code

---
 x/staking/keeper/validator.go | 7 -------
 x/staking/types/keys.go       | 5 -----
 2 files changed, 12 deletions(-)

diff --git a/x/staking/keeper/validator.go b/x/staking/keeper/validator.go
index dd7b6c7751cf..bd4c3b4ed015 100644
--- a/x/staking/keeper/validator.go
+++ b/x/staking/keeper/validator.go
@@ -342,8 +342,6 @@ func (k Keeper) ValidatorsPowerStoreIterator(ctx context.Context) (corestore.Ite
 // GetLastValidatorPower loads the last validator power.
 // Returns zero if the operator was not a validator last block.
 func (k Keeper) GetLastValidatorPower(ctx context.Context, operator sdk.ValAddress) (power int64, err error) {
-	// store := k.storeService.OpenKVStore(ctx)
-	// bz, err := store.Get(types.GetLastValidatorPowerKey(operator))
 	bz, err := k.LastValidatorPower.Get(ctx, operator)
 	if err != nil {
 		return 0, err
@@ -364,25 +362,20 @@ func (k Keeper) GetLastValidatorPower(ctx context.Context, operator sdk.ValAddre
 
 // SetLastValidatorPower sets the last validator power.
 func (k Keeper) SetLastValidatorPower(ctx context.Context, operator sdk.ValAddress, power int64) error {
-	// store := k.storeService.OpenKVStore(ctx)
 	bz, err := k.cdc.Marshal(&gogotypes.Int64Value{Value: power})
 	if err != nil {
 		return err
 	}
-	// return store.Set(types.GetLastValidatorPowerKey(operator), bz)
 	return k.LastValidatorPower.Set(ctx, operator, bz)
 }
 
 // DeleteLastValidatorPower deletes the last validator power.
 func (k Keeper) DeleteLastValidatorPower(ctx context.Context, operator sdk.ValAddress) error {
-	// store := k.storeService.OpenKVStore(ctx)
-	// return store.Delete(types.GetLastValidatorPowerKey(operator))
 	bz, err := k.cdc.Marshal(&gogotypes.Int64Value{Value: 0})
 	if err != nil {
 		return err
 	}
 	return k.LastValidatorPower.Set(ctx, operator, bz)
-	// return k.LastValidatorPower.Remove(ctx, operator)
 }
 
 // lastValidatorsIterator returns an iterator for the consensus validators in the last block
diff --git a/x/staking/types/keys.go b/x/staking/types/keys.go
index 759ce9f57438..2a6e0e7f14fc 100644
--- a/x/staking/types/keys.go
+++ b/x/staking/types/keys.go
@@ -127,11 +127,6 @@ func GetValidatorsByPowerIndexKey(validator Validator, powerReduction math.Int,
 	return key
 }
 
-// // GetLastValidatorPowerKey creates the bonded validator index key for an operator address
-// func GetLastValidatorPowerKey(operator sdk.ValAddress) []byte {
-// 	return append(LastValidatorPowerKey, address.MustLengthPrefix(operator)...)
-// }
-
 // ParseValidatorPowerRankKey parses the validators operator address from power rank key
 func ParseValidatorPowerRankKey(key []byte) (operAddr []byte) {
 	powerBytesLen := 8

From 3c103ee548dacb3d1db4ab9da8451f9514fefd3a Mon Sep 17 00:00:00 2001
From: likhita-809 <likhita@vitwit.com>
Date: Tue, 22 Aug 2023 16:40:02 +0530
Subject: [PATCH 04/13] remove log

---
 x/staking/keeper/validator_test.go | 2 --
 1 file changed, 2 deletions(-)

diff --git a/x/staking/keeper/validator_test.go b/x/staking/keeper/validator_test.go
index 1e95acb6f251..f5015f7844a2 100644
--- a/x/staking/keeper/validator_test.go
+++ b/x/staking/keeper/validator_test.go
@@ -1,7 +1,6 @@
 package keeper_test
 
 import (
-	"fmt"
 	"time"
 
 	abci "github.com/cometbft/cometbft/abci/types"
@@ -78,7 +77,6 @@ func (s *KeeperTestSuite) TestValidator() {
 	// check the last validator power
 	power := int64(100)
 	require.NoError(keeper.SetLastValidatorPower(ctx, valAddr, power))
-	fmt.Printf("valAddr: %v\n", valAddr.String())
 	resPower, err := keeper.GetLastValidatorPower(ctx, valAddr)
 	require.NoError(err)
 	require.Equal(power, resPower)

From 7a6d3f3b8245f69888a4c46cb6d635a4a940082b Mon Sep 17 00:00:00 2001
From: likhita-809 <likhita@vitwit.com>
Date: Thu, 24 Aug 2023 15:58:08 +0530
Subject: [PATCH 05/13] wip: fix few tests

---
 x/staking/keeper/alias_functions.go  | 21 +++++-------
 x/staking/keeper/keeper.go           |  4 +--
 x/staking/keeper/val_state_change.go | 20 +++++-------
 x/staking/keeper/validator.go        | 48 +++++++++++-----------------
 4 files changed, 37 insertions(+), 56 deletions(-)

diff --git a/x/staking/keeper/alias_functions.go b/x/staking/keeper/alias_functions.go
index d9790e784169..dbab19a8d3ed 100644
--- a/x/staking/keeper/alias_functions.go
+++ b/x/staking/keeper/alias_functions.go
@@ -72,27 +72,22 @@ func (k Keeper) IterateBondedValidatorsByPower(ctx context.Context, fn func(inde
 
 // IterateLastValidators iterates through the active validator set and perform the provided function
 func (k Keeper) IterateLastValidators(ctx context.Context, fn func(index int64, validator types.ValidatorI) (stop bool)) error {
-	iterator, err := k.LastValidatorsIterator(ctx)
-	if err != nil {
-		return err
-	}
-	defer iterator.Close()
-
 	i := int64(0)
-
-	for ; iterator.Valid(); iterator.Next() {
-		address := types.AddressFromLastValidatorPowerKey(iterator.Key())
-
-		validator, err := k.GetValidator(ctx, address)
+	err := k.LastValidatorPower.Walk(ctx, nil, func(key []byte, value []byte) (bool, error) {
+		validator, err := k.GetValidator(ctx, key)
 		if err != nil {
-			return err
+			return true, err
 		}
 
 		stop := fn(i, validator) // XXX is this safe will the validator unexposed fields be able to get written to?
 		if stop {
-			break
+			return true, err
 		}
 		i++
+		return false, nil
+	})
+	if err != nil {
+		return err
 	}
 	return nil
 }
diff --git a/x/staking/keeper/keeper.go b/x/staking/keeper/keeper.go
index 87e73cb6972a..e057e6daaa09 100644
--- a/x/staking/keeper/keeper.go
+++ b/x/staking/keeper/keeper.go
@@ -46,7 +46,7 @@ type Keeper struct {
 	UnbondingIndex              collections.Map[uint64, []byte]
 	RedelegationsByValDst       collections.Map[collections.Triple[[]byte, []byte, []byte], []byte]
 	RedelegationsByValSrc       collections.Map[collections.Triple[[]byte, []byte, []byte], []byte]
-	LastValidatorPower          collections.Map[sdk.ValAddress, []byte]
+	LastValidatorPower          collections.Map[[]byte, []byte]
 }
 
 // NewKeeper creates a new staking Keeper instance
@@ -135,7 +135,7 @@ func NewKeeper(
 			),
 			collections.BytesValue,
 		),
-		LastValidatorPower: collections.NewMap(sb, types.LastValidatorPowerKey, "last_validator_power", sdk.LengthPrefixedAddressKey(sdk.ValAddressKey), collections.BytesValue), // nolint: staticcheck // sdk.LengthPrefixedAddressKey is needed to retain state compatibility
+		LastValidatorPower: collections.NewMap(sb, types.LastValidatorPowerKey, "last_validator_power", sdk.LengthPrefixedBytesKey, collections.BytesValue), // nolint: staticcheck // sdk.LengthPrefixedBytesKey is needed to retain state compatibility
 		// key format is: 54 | lengthPrefixedBytes(DstValAddr) | lengthPrefixedBytes(AccAddr) | lengthPrefixedBytes(SrcValAddr)
 		RedelegationsByValDst: collections.NewMap(
 			sb, types.RedelegationByValDstIndexKey,
diff --git a/x/staking/keeper/val_state_change.go b/x/staking/keeper/val_state_change.go
index aee84f9c520e..b8007f283b5c 100644
--- a/x/staking/keeper/val_state_change.go
+++ b/x/staking/keeper/val_state_change.go
@@ -463,23 +463,19 @@ type validatorsByAddr map[string][]byte
 func (k Keeper) getLastValidatorsByAddr(ctx context.Context) (validatorsByAddr, error) {
 	last := make(validatorsByAddr)
 
-	iterator, err := k.LastValidatorsIterator(ctx)
-	if err != nil {
-		return nil, err
-	}
-	defer iterator.Close()
-
-	for ; iterator.Valid(); iterator.Next() {
-		// extract the validator address from the key (prefix is 1-byte, addrLen is 1-byte)
-		valAddr := types.AddressFromLastValidatorPowerKey(iterator.Key())
-		valAddrStr, err := k.validatorAddressCodec.BytesToString(valAddr)
+	err := k.LastValidatorPower.Walk(ctx, nil, func(key []byte, value []byte) (bool, error) {
+		valAddrStr, err := k.validatorAddressCodec.BytesToString(key)
 		if err != nil {
-			return nil, err
+			return true, err
 		}
 
-		powerBytes := iterator.Value()
+		powerBytes := value
 		last[valAddrStr] = make([]byte, len(powerBytes))
 		copy(last[valAddrStr], powerBytes)
+		return false, nil
+	})
+	if err != nil {
+		return nil, err
 	}
 
 	return last, nil
diff --git a/x/staking/keeper/validator.go b/x/staking/keeper/validator.go
index bd4c3b4ed015..289ccd37eb7d 100644
--- a/x/staking/keeper/validator.go
+++ b/x/staking/keeper/validator.go
@@ -358,6 +358,7 @@ func (k Keeper) GetLastValidatorPower(ctx context.Context, operator sdk.ValAddre
 	}
 
 	return intV.GetValue(), nil
+	// return k.LastValidatorPower.Get(ctx, operator.Bytes())
 }
 
 // SetLastValidatorPower sets the last validator power.
@@ -367,6 +368,7 @@ func (k Keeper) SetLastValidatorPower(ctx context.Context, operator sdk.ValAddre
 		return err
 	}
 	return k.LastValidatorPower.Set(ctx, operator, bz)
+	// return k.LastValidatorPower.Set(ctx, operator.Bytes(), power)
 }
 
 // DeleteLastValidatorPower deletes the last validator power.
@@ -375,33 +377,26 @@ func (k Keeper) DeleteLastValidatorPower(ctx context.Context, operator sdk.ValAd
 	if err != nil {
 		return err
 	}
-	return k.LastValidatorPower.Set(ctx, operator, bz)
-}
-
-// lastValidatorsIterator returns an iterator for the consensus validators in the last block
-func (k Keeper) LastValidatorsIterator(ctx context.Context) (corestore.Iterator, error) {
-	store := k.storeService.OpenKVStore(ctx)
-	return store.Iterator(types.LastValidatorPowerKey, storetypes.PrefixEndBytes(types.LastValidatorPowerKey))
+	return k.LastValidatorPower.Set(ctx, operator, bz) // setting power to 0 on deletion
 }
 
 // IterateLastValidatorPowers iterates over last validator powers.
 func (k Keeper) IterateLastValidatorPowers(ctx context.Context, handler func(operator sdk.ValAddress, power int64) (stop bool)) error {
-	iter, err := k.LastValidatorsIterator(ctx)
-	if err != nil {
-		return err
-	}
-
-	for ; iter.Valid(); iter.Next() {
-		addr := sdk.ValAddress(types.AddressFromLastValidatorPowerKey(iter.Key()))
+	err := k.LastValidatorPower.Walk(ctx, nil, func(key []byte, value []byte) (bool, error) {
+		addr := sdk.ValAddress(key)
 		intV := &gogotypes.Int64Value{}
 
-		if err = k.cdc.Unmarshal(iter.Value(), intV); err != nil {
-			return err
+		if err := k.cdc.Unmarshal(value, intV); err != nil {
+			return true, err
 		}
 
 		if handler(addr, intV.GetValue()) {
-			break
+			return true, nil
 		}
+		return false, nil
+	})
+	if err != nil {
+		return err
 	}
 
 	return nil
@@ -409,8 +404,6 @@ func (k Keeper) IterateLastValidatorPowers(ctx context.Context, handler func(ope
 
 // GetLastValidators gets the group of the bonded validators
 func (k Keeper) GetLastValidators(ctx context.Context) (validators []types.Validator, err error) {
-	store := k.storeService.OpenKVStore(ctx)
-
 	// add the actual validator power sorted store
 	maxValidators, err := k.MaxValidators(ctx)
 	if err != nil {
@@ -418,27 +411,24 @@ func (k Keeper) GetLastValidators(ctx context.Context) (validators []types.Valid
 	}
 	validators = make([]types.Validator, maxValidators)
 
-	iterator, err := store.Iterator(types.LastValidatorPowerKey, storetypes.PrefixEndBytes(types.LastValidatorPowerKey))
-	if err != nil {
-		return nil, err
-	}
-	defer iterator.Close()
-
 	i := 0
-	for ; iterator.Valid(); iterator.Next() {
+	err = k.LastValidatorPower.Walk(ctx, nil, func(key []byte, value []byte) (bool, error) {
 		// sanity check
 		if i >= int(maxValidators) {
 			panic("more validators than maxValidators found")
 		}
 
-		address := types.AddressFromLastValidatorPowerKey(iterator.Key())
-		validator, err := k.GetValidator(ctx, address)
+		validator, err := k.GetValidator(ctx, key)
 		if err != nil {
-			return nil, err
+			return true, err
 		}
 
 		validators[i] = validator
 		i++
+		return false, nil
+	})
+	if err != nil {
+		return nil, err
 	}
 
 	return validators[:i], nil // trim

From f20a10f37e48661234a3cab0f1b85b0c39d93956 Mon Sep 17 00:00:00 2001
From: likhita-809 <likhita@vitwit.com>
Date: Thu, 24 Aug 2023 16:31:29 +0530
Subject: [PATCH 06/13] try fixing test

---
 x/staking/keeper/keeper.go    | 2 +-
 x/staking/keeper/validator.go | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/x/staking/keeper/keeper.go b/x/staking/keeper/keeper.go
index e057e6daaa09..42d5f68cd63a 100644
--- a/x/staking/keeper/keeper.go
+++ b/x/staking/keeper/keeper.go
@@ -135,7 +135,7 @@ func NewKeeper(
 			),
 			collections.BytesValue,
 		),
-		LastValidatorPower: collections.NewMap(sb, types.LastValidatorPowerKey, "last_validator_power", sdk.LengthPrefixedBytesKey, collections.BytesValue), // nolint: staticcheck // sdk.LengthPrefixedBytesKey is needed to retain state compatibility
+		LastValidatorPower: collections.NewMap(sb, types.LastValidatorPowerKey, "last_validator_power", sdk.LengthPrefixedBytesKey, collections.BytesValue), // sdk.LengthPrefixedBytesKey is needed to retain state compatibility
 		// key format is: 54 | lengthPrefixedBytes(DstValAddr) | lengthPrefixedBytes(AccAddr) | lengthPrefixedBytes(SrcValAddr)
 		RedelegationsByValDst: collections.NewMap(
 			sb, types.RedelegationByValDstIndexKey,
diff --git a/x/staking/keeper/validator.go b/x/staking/keeper/validator.go
index 289ccd37eb7d..b27d00fdbd4a 100644
--- a/x/staking/keeper/validator.go
+++ b/x/staking/keeper/validator.go
@@ -415,7 +415,8 @@ func (k Keeper) GetLastValidators(ctx context.Context) (validators []types.Valid
 	err = k.LastValidatorPower.Walk(ctx, nil, func(key []byte, value []byte) (bool, error) {
 		// sanity check
 		if i >= int(maxValidators) {
-			panic("more validators than maxValidators found")
+			// panic("more validators than maxValidators found")
+			return true, nil
 		}
 
 		validator, err := k.GetValidator(ctx, key)

From c301ee34e42a85db133786ef950ef8237bea013e Mon Sep 17 00:00:00 2001
From: likhita-809 <likhita@vitwit.com>
Date: Thu, 24 Aug 2023 16:51:09 +0530
Subject: [PATCH 07/13] fix lint

---
 x/staking/keeper/alias_functions.go  | 2 +-
 x/staking/keeper/keeper_test.go      | 3 +--
 x/staking/keeper/val_state_change.go | 2 +-
 x/staking/keeper/validator.go        | 4 ++--
 4 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/x/staking/keeper/alias_functions.go b/x/staking/keeper/alias_functions.go
index dbab19a8d3ed..46b46247be1e 100644
--- a/x/staking/keeper/alias_functions.go
+++ b/x/staking/keeper/alias_functions.go
@@ -73,7 +73,7 @@ func (k Keeper) IterateBondedValidatorsByPower(ctx context.Context, fn func(inde
 // IterateLastValidators iterates through the active validator set and perform the provided function
 func (k Keeper) IterateLastValidators(ctx context.Context, fn func(index int64, validator types.ValidatorI) (stop bool)) error {
 	i := int64(0)
-	err := k.LastValidatorPower.Walk(ctx, nil, func(key []byte, value []byte) (bool, error) {
+	err := k.LastValidatorPower.Walk(ctx, nil, func(key, value []byte) (bool, error) {
 		validator, err := k.GetValidator(ctx, key)
 		if err != nil {
 			return true, err
diff --git a/x/staking/keeper/keeper_test.go b/x/staking/keeper/keeper_test.go
index cdd8d9a36bce..51beb1a5dfe4 100644
--- a/x/staking/keeper/keeper_test.go
+++ b/x/staking/keeper/keeper_test.go
@@ -5,6 +5,7 @@ import (
 
 	cmtproto "github.com/cometbft/cometbft/proto/tendermint/types"
 	cmttime "github.com/cometbft/cometbft/types/time"
+	gogotypes "github.com/cosmos/gogoproto/types"
 	"github.com/golang/mock/gomock"
 	"github.com/stretchr/testify/suite"
 
@@ -12,8 +13,6 @@ import (
 	"cosmossdk.io/math"
 	storetypes "cosmossdk.io/store/types"
 
-	gogotypes "github.com/cosmos/gogoproto/types"
-
 	"github.com/cosmos/cosmos-sdk/baseapp"
 	"github.com/cosmos/cosmos-sdk/codec"
 	"github.com/cosmos/cosmos-sdk/codec/address"
diff --git a/x/staking/keeper/val_state_change.go b/x/staking/keeper/val_state_change.go
index b8007f283b5c..edb4d32e43d8 100644
--- a/x/staking/keeper/val_state_change.go
+++ b/x/staking/keeper/val_state_change.go
@@ -463,7 +463,7 @@ type validatorsByAddr map[string][]byte
 func (k Keeper) getLastValidatorsByAddr(ctx context.Context) (validatorsByAddr, error) {
 	last := make(validatorsByAddr)
 
-	err := k.LastValidatorPower.Walk(ctx, nil, func(key []byte, value []byte) (bool, error) {
+	err := k.LastValidatorPower.Walk(ctx, nil, func(key, value []byte) (bool, error) {
 		valAddrStr, err := k.validatorAddressCodec.BytesToString(key)
 		if err != nil {
 			return true, err
diff --git a/x/staking/keeper/validator.go b/x/staking/keeper/validator.go
index b27d00fdbd4a..2a3ad37c1227 100644
--- a/x/staking/keeper/validator.go
+++ b/x/staking/keeper/validator.go
@@ -382,7 +382,7 @@ func (k Keeper) DeleteLastValidatorPower(ctx context.Context, operator sdk.ValAd
 
 // IterateLastValidatorPowers iterates over last validator powers.
 func (k Keeper) IterateLastValidatorPowers(ctx context.Context, handler func(operator sdk.ValAddress, power int64) (stop bool)) error {
-	err := k.LastValidatorPower.Walk(ctx, nil, func(key []byte, value []byte) (bool, error) {
+	err := k.LastValidatorPower.Walk(ctx, nil, func(key, value []byte) (bool, error) {
 		addr := sdk.ValAddress(key)
 		intV := &gogotypes.Int64Value{}
 
@@ -412,7 +412,7 @@ func (k Keeper) GetLastValidators(ctx context.Context) (validators []types.Valid
 	validators = make([]types.Validator, maxValidators)
 
 	i := 0
-	err = k.LastValidatorPower.Walk(ctx, nil, func(key []byte, value []byte) (bool, error) {
+	err = k.LastValidatorPower.Walk(ctx, nil, func(key, value []byte) (bool, error) {
 		// sanity check
 		if i >= int(maxValidators) {
 			// panic("more validators than maxValidators found")

From 63e13853fdb9d2d1471e88575d8745afd7765191 Mon Sep 17 00:00:00 2001
From: likhita-809 <likhita@vitwit.com>
Date: Mon, 28 Aug 2023 13:31:26 +0530
Subject: [PATCH 08/13] try fixing tests

---
 x/staking/keeper/validator.go      | 6 +-----
 x/staking/keeper/validator_test.go | 3 ++-
 2 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/x/staking/keeper/validator.go b/x/staking/keeper/validator.go
index 3f00ba8ec256..534247f7d036 100644
--- a/x/staking/keeper/validator.go
+++ b/x/staking/keeper/validator.go
@@ -373,11 +373,7 @@ func (k Keeper) SetLastValidatorPower(ctx context.Context, operator sdk.ValAddre
 
 // DeleteLastValidatorPower deletes the last validator power.
 func (k Keeper) DeleteLastValidatorPower(ctx context.Context, operator sdk.ValAddress) error {
-	bz, err := k.cdc.Marshal(&gogotypes.Int64Value{Value: 0})
-	if err != nil {
-		return err
-	}
-	return k.LastValidatorPower.Set(ctx, operator, bz) // setting power to 0 on deletion
+	return k.LastValidatorPower.Remove(ctx, operator) // setting power to 0 on deletion
 }
 
 // IterateLastValidatorPowers iterates over last validator powers.
diff --git a/x/staking/keeper/validator_test.go b/x/staking/keeper/validator_test.go
index f5015f7844a2..f3afffa87bdd 100644
--- a/x/staking/keeper/validator_test.go
+++ b/x/staking/keeper/validator_test.go
@@ -6,6 +6,7 @@ import (
 	abci "github.com/cometbft/cometbft/abci/types"
 	"github.com/golang/mock/gomock"
 
+	"cosmossdk.io/collections"
 	"cosmossdk.io/math"
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
@@ -82,7 +83,7 @@ func (s *KeeperTestSuite) TestValidator() {
 	require.Equal(power, resPower)
 	require.NoError(keeper.DeleteLastValidatorPower(ctx, valAddr))
 	resPower, err = keeper.GetLastValidatorPower(ctx, valAddr)
-	require.NoError(err)
+	require.Error(err, collections.ErrNotFound)
 	require.Equal(int64(0), resPower)
 }
 

From ee4a9320743316820ae8f31702482171d1cae3f7 Mon Sep 17 00:00:00 2001
From: likhita-809 <likhita@vitwit.com>
Date: Mon, 28 Aug 2023 13:56:07 +0530
Subject: [PATCH 09/13] cleanup

---
 x/staking/keeper/validator.go | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/x/staking/keeper/validator.go b/x/staking/keeper/validator.go
index 534247f7d036..39bf25b3bf7c 100644
--- a/x/staking/keeper/validator.go
+++ b/x/staking/keeper/validator.go
@@ -358,7 +358,6 @@ func (k Keeper) GetLastValidatorPower(ctx context.Context, operator sdk.ValAddre
 	}
 
 	return intV.GetValue(), nil
-	// return k.LastValidatorPower.Get(ctx, operator.Bytes())
 }
 
 // SetLastValidatorPower sets the last validator power.
@@ -368,12 +367,11 @@ func (k Keeper) SetLastValidatorPower(ctx context.Context, operator sdk.ValAddre
 		return err
 	}
 	return k.LastValidatorPower.Set(ctx, operator, bz)
-	// return k.LastValidatorPower.Set(ctx, operator.Bytes(), power)
 }
 
 // DeleteLastValidatorPower deletes the last validator power.
 func (k Keeper) DeleteLastValidatorPower(ctx context.Context, operator sdk.ValAddress) error {
-	return k.LastValidatorPower.Remove(ctx, operator) // setting power to 0 on deletion
+	return k.LastValidatorPower.Remove(ctx, operator)
 }
 
 // IterateLastValidatorPowers iterates over last validator powers.
@@ -411,8 +409,7 @@ func (k Keeper) GetLastValidators(ctx context.Context) (validators []types.Valid
 	err = k.LastValidatorPower.Walk(ctx, nil, func(key, value []byte) (bool, error) {
 		// sanity check
 		if i >= int(maxValidators) {
-			// panic("more validators than maxValidators found")
-			return true, nil
+			panic("more validators than maxValidators found")
 		}
 
 		validator, err := k.GetValidator(ctx, key)

From c0b5325d8ff0edeccca8d7c9e3c94c3425309198 Mon Sep 17 00:00:00 2001
From: likhita-809 <likhita@vitwit.com>
Date: Mon, 28 Aug 2023 15:51:14 +0530
Subject: [PATCH 10/13] add changelog

---
 CHANGELOG.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 734ee100dbfe..200d5161ff70 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -56,6 +56,9 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### API Breaking Changes
 
+* (x/staking) [#17498](https://github.com/cosmos/cosmos-sdk/pull/17498) Use collections for `LastValidatorPower`:
+    * remove from `types`: `GetLastValidatorPowerKey`
+    * remove from `Keeper`: `LastValidatorsIterator`
 * (x/staking) [#17270](https://github.com/cosmos/cosmos-sdk/pull/17270) Use collections for `UnbondingDelegation`:
     * remove from `types`: `GetUBDsKey`
     * remove from `Keeper`: `IterateUnbondingDelegations`, `IterateDelegatorUnbondingDelegations`

From ef2a887a77eb6be3ee597bd3c61ee2d0c8845c6d Mon Sep 17 00:00:00 2001
From: likhita-809 <likhita@vitwit.com>
Date: Wed, 30 Aug 2023 15:05:02 +0530
Subject: [PATCH 11/13] address review comments

---
 x/staking/genesis.go                         | 13 ++++++++----
 x/staking/keeper/alias_functions.go          | 22 --------------------
 x/staking/keeper/keeper_test.go              | 20 +++++++++++-------
 x/staking/keeper/val_state_change.go         |  4 +---
 x/staking/testutil/expected_keepers_mocks.go | 14 -------------
 x/staking/types/expected_keepers.go          |  4 ----
 6 files changed, 22 insertions(+), 55 deletions(-)

diff --git a/x/staking/genesis.go b/x/staking/genesis.go
index 1d4cd64e4bba..6b249b370b9c 100644
--- a/x/staking/genesis.go
+++ b/x/staking/genesis.go
@@ -13,16 +13,21 @@ import (
 
 // WriteValidators returns a slice of bonded genesis validators.
 func WriteValidators(ctx sdk.Context, keeper *keeper.Keeper) (vals []cmttypes.GenesisValidator, returnErr error) {
-	err := keeper.IterateLastValidators(ctx, func(_ int64, validator types.ValidatorI) (stop bool) {
+	err := keeper.LastValidatorPower.Walk(ctx, nil, func(key, value []byte) (bool, error) {
+		validator, err := keeper.GetValidator(ctx, key)
+		if err != nil {
+			return true, err
+		}
+
 		pk, err := validator.ConsPubKey()
 		if err != nil {
 			returnErr = err
-			return true
+			return true, err
 		}
 		cmtPk, err := cryptocodec.ToCmtPubKeyInterface(pk)
 		if err != nil {
 			returnErr = err
-			return true
+			return true, err
 		}
 
 		vals = append(vals, cmttypes.GenesisValidator{
@@ -32,7 +37,7 @@ func WriteValidators(ctx sdk.Context, keeper *keeper.Keeper) (vals []cmttypes.Ge
 			Name:    validator.GetMoniker(),
 		})
 
-		return false
+		return false, nil
 	})
 	if err != nil {
 		return nil, err
diff --git a/x/staking/keeper/alias_functions.go b/x/staking/keeper/alias_functions.go
index 46b46247be1e..1a00b71bc00a 100644
--- a/x/staking/keeper/alias_functions.go
+++ b/x/staking/keeper/alias_functions.go
@@ -70,28 +70,6 @@ func (k Keeper) IterateBondedValidatorsByPower(ctx context.Context, fn func(inde
 	return nil
 }
 
-// IterateLastValidators iterates through the active validator set and perform the provided function
-func (k Keeper) IterateLastValidators(ctx context.Context, fn func(index int64, validator types.ValidatorI) (stop bool)) error {
-	i := int64(0)
-	err := k.LastValidatorPower.Walk(ctx, nil, func(key, value []byte) (bool, error) {
-		validator, err := k.GetValidator(ctx, key)
-		if err != nil {
-			return true, err
-		}
-
-		stop := fn(i, validator) // XXX is this safe will the validator unexposed fields be able to get written to?
-		if stop {
-			return true, err
-		}
-		i++
-		return false, nil
-	})
-	if err != nil {
-		return err
-	}
-	return nil
-}
-
 // Validator gets the Validator interface for a particular address
 func (k Keeper) Validator(ctx context.Context, address sdk.ValAddress) (types.ValidatorI, error) {
 	return k.GetValidator(ctx, address)
diff --git a/x/staking/keeper/keeper_test.go b/x/staking/keeper/keeper_test.go
index a68a51e4be5b..998a6a00eb5f 100644
--- a/x/staking/keeper/keeper_test.go
+++ b/x/staking/keeper/keeper_test.go
@@ -189,6 +189,7 @@ func getValidatorKey(operatorAddr sdk.ValAddress) []byte {
 	return append(validatorsKey, addresstypes.MustLengthPrefix(operatorAddr)...)
 }
 
+// getLastValidatorPowerKey creates the bonded validator index key for an operator address
 func getLastValidatorPowerKey(operator sdk.ValAddress) []byte {
 	lastValidatorPowerKey := []byte{0x11}
 	return append(lastValidatorPowerKey, addresstypes.MustLengthPrefix(operator)...)
@@ -197,19 +198,19 @@ func getLastValidatorPowerKey(operator sdk.ValAddress) []byte {
 func (s *KeeperTestSuite) TestLastTotalPowerMigrationToColls() {
 	s.SetupTest()
 
-	_, valAddrs := createValAddrs(101)
-
-	bz, err := s.cdc.Marshal(&gogotypes.Int64Value{Value: 1})
-	s.Require().NoError(err)
+	_, valAddrs := createValAddrs(100)
 
-	err = testutil.DiffCollectionsMigration(
+	err := testutil.DiffCollectionsMigration(
 		s.ctx,
 		s.key,
 		100,
 		func(i int64) {
+			bz, err := s.cdc.Marshal(&gogotypes.Int64Value{Value: i})
+			s.Require().NoError(err)
+
 			s.ctx.KVStore(s.key).Set(getLastValidatorPowerKey(valAddrs[i]), bz)
 		},
-		"6cd9b908445fbe0b280b82cac51758cdb125882674a91d348b690dac4b7055cb",
+		"f28811f2b0a0ab9db60cdcae93680faff9dbadd4a3a8a2d088bb19b0428ad3a9",
 	)
 	s.Require().NoError(err)
 
@@ -218,10 +219,13 @@ func (s *KeeperTestSuite) TestLastTotalPowerMigrationToColls() {
 		s.key,
 		100,
 		func(i int64) {
-			err := s.stakingKeeper.LastValidatorPower.Set(s.ctx, valAddrs[i], bz)
+			bz, err := s.cdc.Marshal(&gogotypes.Int64Value{Value: i})
+			s.Require().NoError(err)
+
+			err = s.stakingKeeper.LastValidatorPower.Set(s.ctx, valAddrs[i], bz)
 			s.Require().NoError(err)
 		},
-		"6cd9b908445fbe0b280b82cac51758cdb125882674a91d348b690dac4b7055cb",
+		"f28811f2b0a0ab9db60cdcae93680faff9dbadd4a3a8a2d088bb19b0428ad3a9",
 	)
 	s.Require().NoError(err)
 }
diff --git a/x/staking/keeper/val_state_change.go b/x/staking/keeper/val_state_change.go
index edb4d32e43d8..c0c996a28edb 100644
--- a/x/staking/keeper/val_state_change.go
+++ b/x/staking/keeper/val_state_change.go
@@ -469,9 +469,7 @@ func (k Keeper) getLastValidatorsByAddr(ctx context.Context) (validatorsByAddr,
 			return true, err
 		}
 
-		powerBytes := value
-		last[valAddrStr] = make([]byte, len(powerBytes))
-		copy(last[valAddrStr], powerBytes)
+		last[valAddrStr] = value
 		return false, nil
 	})
 	if err != nil {
diff --git a/x/staking/testutil/expected_keepers_mocks.go b/x/staking/testutil/expected_keepers_mocks.go
index 1bdee0360354..470f112cfc84 100644
--- a/x/staking/testutil/expected_keepers_mocks.go
+++ b/x/staking/testutil/expected_keepers_mocks.go
@@ -336,20 +336,6 @@ func (mr *MockValidatorSetMockRecorder) IterateBondedValidatorsByPower(arg0, arg
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "IterateBondedValidatorsByPower", reflect.TypeOf((*MockValidatorSet)(nil).IterateBondedValidatorsByPower), arg0, arg1)
 }
 
-// IterateLastValidators mocks base method.
-func (m *MockValidatorSet) IterateLastValidators(arg0 context.Context, arg1 func(int64, types0.ValidatorI) bool) error {
-	m.ctrl.T.Helper()
-	ret := m.ctrl.Call(m, "IterateLastValidators", arg0, arg1)
-	ret0, _ := ret[0].(error)
-	return ret0
-}
-
-// IterateLastValidators indicates an expected call of IterateLastValidators.
-func (mr *MockValidatorSetMockRecorder) IterateLastValidators(arg0, arg1 interface{}) *gomock.Call {
-	mr.mock.ctrl.T.Helper()
-	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "IterateLastValidators", reflect.TypeOf((*MockValidatorSet)(nil).IterateLastValidators), arg0, arg1)
-}
-
 // IterateValidators mocks base method.
 func (m *MockValidatorSet) IterateValidators(arg0 context.Context, arg1 func(int64, types0.ValidatorI) bool) error {
 	m.ctrl.T.Helper()
diff --git a/x/staking/types/expected_keepers.go b/x/staking/types/expected_keepers.go
index 3c3ae276ed16..0cd5f453f512 100644
--- a/x/staking/types/expected_keepers.go
+++ b/x/staking/types/expected_keepers.go
@@ -52,10 +52,6 @@ type ValidatorSet interface {
 	IterateBondedValidatorsByPower(context.Context,
 		func(index int64, validator ValidatorI) (stop bool)) error
 
-	// iterate through the consensus validator set of the last block by operator address, execute func for each validator
-	IterateLastValidators(context.Context,
-		func(index int64, validator ValidatorI) (stop bool)) error
-
 	Validator(context.Context, sdk.ValAddress) (ValidatorI, error)            // get a particular validator by operator address
 	ValidatorByConsAddr(context.Context, sdk.ConsAddress) (ValidatorI, error) // get a particular validator by consensus address
 	TotalBondedTokens(context.Context) (math.Int, error)                      // total bonded tokens within the validator set

From 92cb5351b909b2c5350ec57c4eaa5e0afb9587cd Mon Sep 17 00:00:00 2001
From: likhita-809 <likhita@vitwit.com>
Date: Wed, 30 Aug 2023 15:07:44 +0530
Subject: [PATCH 12/13] update changelog

---
 CHANGELOG.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index be83413766f8..d58b5d9add4f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -61,7 +61,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 * (x/staking) [#17498](https://github.com/cosmos/cosmos-sdk/pull/17498) Use collections for `LastValidatorPower`:
     * remove from `types`: `GetLastValidatorPowerKey`
-    * remove from `Keeper`: `LastValidatorsIterator`
+    * remove from `Keeper`: `LastValidatorsIterator`, `IterateLastValidators`
 * (x/staking) [#17291](https://github.com/cosmos/cosmos-sdk/pull/17291) Use collections for `UnbondingDelegationByValIndex`:
     * remove from `types`: `GetUBDKeyFromValIndexKey`, `GetUBDsByValIndexKey`, `GetUBDByValIndexKey`
 * (x/slashing) [#17568](https://github.com/cosmos/cosmos-sdk/pull/17568) Use collections for `ValidatorMissedBlockBitmap`:

From 633714caf258b529fb33df4401d18732fe3eb922 Mon Sep 17 00:00:00 2001
From: likhita-809 <likhita@vitwit.com>
Date: Wed, 30 Aug 2023 15:34:43 +0530
Subject: [PATCH 13/13] fix lint

---
 x/staking/genesis.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/x/staking/genesis.go b/x/staking/genesis.go
index 6b249b370b9c..005ec107a5b4 100644
--- a/x/staking/genesis.go
+++ b/x/staking/genesis.go
@@ -43,7 +43,7 @@ func WriteValidators(ctx sdk.Context, keeper *keeper.Keeper) (vals []cmttypes.Ge
 		return nil, err
 	}
 
-	return
+	return vals, returnErr
 }
 
 // ValidateGenesis validates the provided staking genesis state to ensure the