Girazoki enable native asset cross chain transfer in moonriver

[girazoki]

What does it do?

Enables transfer of MOVR through XCM to moonriver. For now it is not enabled in Moonbeam, but if suggested I can add it too.

Basically adds to AssetTransactors both XcmCurrencyAdapter for incoming assets matching SelfReserveRepresentations, which include OldAnchoringSelfReserve and NewAnchoringSelfReserve.

The first matches incoming assets to

pub OldAnchoringSelfReserve: MultiLocation = MultiLocation {
		parents:1,
		interior: Junctions::X2(
			Parachain(ParachainInfo::parachain_id().into()),
			PalletInstance(<Balances as PalletInfoAccess>::index() as u8)
		)
};

while the second matches incoming assets to:

pub NewAnchoringSelfReserve: MultiLocation = MultiLocation {
		parents:0,
		interior: Junctions::X1(
			PalletInstance(<Balances as PalletInfoAccess>::index() as u8)
		)
	};

Both represent our balances pallet, which is how we refer to our MOVR token. Both representations are necessary because of paritytech/polkadot#4470, which was introduced in 0.9.16 and which changes the way we receive our own token from absolute to relative view. Hence, we need to handle both pre and post 0.9.16 versions.

Additionally, we change the usage of PalletInfo trait to PalletInfoAccess, because the latter does not use unwraps.

Also, tests are added to runtime/moonriver/xcm_tests.ts sending the MOVR token.

What important points reviewers should know?

Is there something left for follow-up PRs?

What alternative implementations were considered?

Are there relevant PRs or issues in other repositories (Substrate, Polkadot, Frontier, Cumulus)?

What value does it bring to the blockchain users?

[notlesh]

We should do some basic testing to ensure this is reasonable for your use case. It appears to be taken from #1218, which is still a WIP.

[girazoki]

You are right in the sense that a token transfer through XCM would cost 50_000_000_000_000, or essentially, 50microMOVR. Maybe this is too low since for KSM we are charging 0.1KSM. I will increase it to match it

[girazoki]

I increased it to 100KILOWEI. This means that for 1e9 weight (roughly, the amount needed for a token transfer in XCM) we charge 0.1milliMOVR, which I think gets us closer to what we charge for other assets

[notlesh]

Nothing looks wrong to me here, but I don't have much context for the change that you're making. Maybe a short description of the PR (and any links to related upstream PRs) would help.

[girazoki]

Updated the description, let me know if it feels better