chore: remove syncUpgradeSequence (cosmos#5489)

* chore: remove syncUpgradeSequence

* remove unused import

modules/core/04-channel/keeper/export_test.go

@@ -25,11 +25,6 @@ func (k Keeper) CheckForUpgradeCompatibility(ctx sdk.Context, upgradeFields, cou
 	return k.checkForUpgradeCompatibility(ctx, upgradeFields, counterpartyUpgradeFields)
 }
 
-// SyncUpgradeSequence is a wrapper around syncUpgradeSequence to allow the function to be directly called in tests.
-func (k Keeper) SyncUpgradeSequence(ctx sdk.Context, portID, channelID string, channel types.Channel, counterpartyUpgradeSequence uint64) error {
-	return k.syncUpgradeSequence(ctx, portID, channelID, channel, counterpartyUpgradeSequence)
-}
-
 // WriteErrorReceipt is a wrapper around writeErrorReceipt to allow the function to be directly called in tests.
 func (k Keeper) WriteErrorReceipt(ctx sdk.Context, portID, channelID string, upgradeError *types.UpgradeError) {
 	k.writeErrorReceipt(ctx, portID, channelID, upgradeError)

modules/core/04-channel/keeper/upgrade.go

@@ -6,7 +6,6 @@ import (
 	"slices"
 
 	errorsmod "cosmossdk.io/errors"
-	sdkmath "cosmossdk.io/math"
 
 	"github.com/cosmos/cosmos-sdk/telemetry"
 	sdk "github.com/cosmos/cosmos-sdk/types"
@@ -840,25 +839,6 @@ func (k Keeper) getAbsoluteUpgradeTimeout(ctx sdk.Context) types.Timeout {
 	return types.NewTimeout(clienttypes.ZeroHeight(), uint64(ctx.BlockTime().UnixNano())+upgradeTimeout.Timestamp)
 }
 
-// syncUpgradeSequence ensures current upgrade handshake only continues if both channels are using the same upgrade sequence,
-// otherwise an upgrade error is returned so that an error receipt will be written so that the upgrade handshake may be attempted again with synchronized sequences.
-func (k Keeper) syncUpgradeSequence(ctx sdk.Context, portID, channelID string, channel types.Channel, counterpartyUpgradeSequence uint64) error {
-	// save the previous upgrade sequence for the error message
-	prevUpgradeSequence := channel.UpgradeSequence
-
-	if counterpartyUpgradeSequence != channel.UpgradeSequence {
-		// error on the higher sequence so that both chains synchronize on a fresh sequence
-		channel.UpgradeSequence = sdkmath.Max(counterpartyUpgradeSequence, channel.UpgradeSequence)
-		k.SetChannel(ctx, portID, channelID, channel)
-
-		return types.NewUpgradeError(channel.UpgradeSequence, errorsmod.Wrapf(
-			types.ErrInvalidUpgradeSequence, "expected upgrade sequence (%d) to match counterparty upgrade sequence (%d)", prevUpgradeSequence, counterpartyUpgradeSequence),
-		)
-	}
-
-	return nil
-}
-
 // checkForUpgradeCompatibility checks performs stateful validation of self upgrade fields relative to counterparty upgrade.
 func (k Keeper) checkForUpgradeCompatibility(ctx sdk.Context, upgradeFields, counterpartyUpgradeFields types.UpgradeFields) error {
 	// assert that both sides propose the same channel ordering

modules/core/04-channel/keeper/upgrade_test.go

@@ -2690,64 +2690,6 @@ func (suite *KeeperTestSuite) TestCheckForUpgradeCompatibility() {
 	}
 }
 
-func (suite *KeeperTestSuite) TestSyncUpgradeSequence() {
-	var (
-		path                        *ibctesting.Path
-		counterpartyUpgradeSequence uint64
-	)
-
-	testCases := []struct {
-		name     string
-		malleate func()
-		expError error
-	}{
-		{
-			"success",
-			func() {},
-			nil,
-		},
-		{
-			"upgrade sequence mismatch, endpointB channel upgrade sequence is ahead",
-			func() {
-				channel := path.EndpointB.GetChannel()
-				channel.UpgradeSequence = 10
-				path.EndpointB.SetChannel(channel)
-			},
-			types.NewUpgradeError(10, types.ErrInvalidUpgradeSequence), // max sequence will be returned
-		},
-	}
-
-	for _, tc := range testCases {
-		tc := tc
-		suite.Run(tc.name, func() {
-			suite.SetupTest()
-
-			path = ibctesting.NewPath(suite.chainA, suite.chainB)
-			suite.coordinator.Setup(path)
-
-			path.EndpointA.ChannelConfig.ProposedUpgrade.Fields.Version = mock.UpgradeVersion
-			path.EndpointB.ChannelConfig.ProposedUpgrade.Fields.Version = mock.UpgradeVersion
-
-			err := path.EndpointA.ChanUpgradeInit()
-			suite.Require().NoError(err)
-
-			err = path.EndpointB.ChanUpgradeInit()
-			suite.Require().NoError(err)
-
-			counterpartyUpgradeSequence = 1
-
-			tc.malleate()
-
-			err = suite.chainB.GetSimApp().IBCKeeper.ChannelKeeper.SyncUpgradeSequence(suite.chainB.GetContext(), path.EndpointB.ChannelConfig.PortID, path.EndpointB.ChannelID, path.EndpointB.GetChannel(), counterpartyUpgradeSequence)
-			if tc.expError != nil {
-				suite.Require().ErrorIs(err, tc.expError)
-			} else {
-				suite.Require().NoError(err)
-			}
-		})
-	}
-}
-
 func (suite *KeeperTestSuite) TestChanUpgradeCrossingHelloWithHistoricalProofs() {
 	var path *ibctesting.Path