Make xcm config index friendly

[yrong]

⚠️ Breaking Changes ⚠️

XCMv2 will no longer be supported.

What does it do?

Always use TrailingSetTopicAsId and WithUniqueTopic to be consistent with system Parachains.

What value does it bring to the blockchain users?

Make indexing the Xcm across multiple chains a bit easier. e.g: a transfer from Moonbeam to Ethereum:

• Successful submit on moonbeam
  https://moonbeam.subscan.io/extrinsic/8501143-6
• Transfer initiated on asset hub.
  https://assethub-polkadot.subscan.io/block/7645765?tab=event&event=7645765-10
• Transfer queued on bridge hub.
  https://bridgehub-polkadot.subscan.io/block/3961093?tab=event&event=3961093-9
• Transfer completed on Ethereum.
  https://etherscan.io/tx/0xf1883bbb761ffff094a0bb513aae1d3f8d38e6c72fe6a1267fd87e3ef97cd44b

[RomarQ]

LGTM

[yrong]

@RomarQ @Agusrodri
Thanks for the review! I add another change to use WithUniqueTopic sending outbound Xcm. Please take another look to see if that makes sense.

[alistair-singh]

+1

[RomarQ]

@RomarQ @Agusrodri Thanks for the review! I add another change to use WithUniqueTopic sending outbound Xcm. Please take another look to see if that makes sense.

We may need to wait for safeXcmVersion to be set to v3, since SetTopic does not exist in XCMv2. Currently in progress, but will take some time since it needs to go through governance.

Context: SetTopic does not exist on v2

@Agusrodri @albertov19 do you guys agree?

[Agusrodri]

@RomarQ @Agusrodri Thanks for the review! I add another change to use WithUniqueTopic sending outbound Xcm. Please take another look to see if that makes sense.

We may need to wait for safeXcmVersion to be set to v3, since SetTopic does not exist in XCMv2. Currently in progress, but will take some time since it needs to go through governance.

Context: SetTopic does not exist on v2

@Agusrodri @albertov19 do you guys agree?

I think that issue won't happen, as both Polkadot and Kusama already recognizes V4 as the XCM version for Moonbeam and Moonriver respectively.

The issue mentioned there, is due to the fact that the relay chain thinks that the parachain is configured in a lower version than the one it is being used to send the message.

You can check this by querying the xcmPallet.supportedVersion storage on each relay. You will notice that all parachains in both Kusama and Polkadot are configured to V4.

See this moonbeam forum post for more context.

[albertov19]

@RomarQ @Agusrodri Thanks for the review! I add another change to use WithUniqueTopic sending outbound Xcm. Please take another look to see if that makes sense.

We may need to wait for safeXcmVersion to be set to v3, since SetTopic does not exist in XCMv2. Currently in progress, but will take some time since it needs to go through governance.

Context: SetTopic does not exist on v2

@Agusrodri @albertov19 do you guys agree?

Agree with @Agusrodri - Either way it would be good practice to bump safe xcm version. The issue is that this is a root track proposal and it requires a hefty decision deposit. I'm coordinating but this can take 1 month to enact at least.

[RomarQ]

@yrong please merge the latest changes from master and fix the tests.

[Agusrodri]

I took a deeper look and indeed it fails when converting to V2 (our safeXcmVersion). It performs the conversion inside wrap_version function from polkadot xcm pallet:

• https://github.com/paritytech/polkadot-sdk/blob/master/cumulus/primitives/utility/src/lib.rs#L74
• https://github.com/paritytech/polkadot-sdk/blob/master/polkadot/xcm/pallet-xcm/src/lib.rs#L3097

This means we actually need to wait for the proposal that bumps the safeXcmVersion to 3 for this new router to work.

[RomarQ]

Both moonriver and moonbeam are in the process to update safeXcmVerstion to 3. The changes look good to me 👍

[pLabarta]

👍