Make enabling slashes on transfers a one-liner

[ValarDragon]

Summary

Lets make the upgrade handler code for chains to upgrade to support upon switching to IBC v3.1.0 a one-liner, that they import from the app-transfer module.

Problem Definition / Proposal

The code for the upgrade is currently including the following in your upgrade struct:

        var newTraces []ibctransfertypes.DenomTrace
        app.TransferKeeper.IterateDenomTraces(ctx,
            func(dt ibctransfertypes.DenomTrace) bool {
                // check if the new way of splitting FullDenom
                // into Trace and BaseDenom passes validation and
                // is the same as the current DenomTrace.
                // If it isn't then store the new DenomTrace in the list of new traces.
                newTrace := ibctransfertypes.ParseDenomTrace(dt.GetFullDenomPath())
                if err := newTrace.Validate(); err == nil && !equalTraces(newTrace, dt) {
                    newTraces = append(newTraces, newTrace)
                }

                return false
            })

        // replace the outdated traces with the new trace information
        for _, nt := range newTraces {
            app.TransferKeeper.SetDenomTrace(ctx, nt)
        }

Seems to me that this would be better being:

ibctransfertypes.UpgradeToSupportSlashes(ctx, app.TransferKeeper)

for chains to all adopt this more quickly. This would save several lines from the upgrade. Or you could make this use migrations on the TransferKeeper directly. This would be preferrred, since then the upgrade would just be a go.mod update!

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[ValarDragon]

Actually is it viable to make a new patch or minor release, and just bump the transfer consensus version to 2.0 https://github.com/cosmos/ibc-go/blob/main/modules/apps/transfer/module.go, and setup a migration handler? That way chains can update the import in the go.mod, and the rest will 'justwork.TM' :)

You'd do this by bumping consensus version to 2, and setting up a migration handler: https://github.com/cosmos/cosmos-sdk/blob/main/x/bank/module.go#L109-L112

[crodriguezvega]

Thanks for the idea, @ValarDragon! This would be indeed a good improvement for the migrations!