Burning fee allowed for system parachain?

[xlc]

https://github.com/paritytech/cumulus/blob/66887505e6c5ef89ce9f88fc4ec368eb858b1b92/parachains/runtimes/assets/statemint/src/xcm_config.rs#L314

To my understanding, this will burn all XCM fees.

Two questions:

• Shouldn't fee be sent to collator?
• Can system parachain allowed to burn relaychain tokens (without notifying relaychain)? Wouldn't this cause imbalances? i.e. balance mismatch between relaychain's checking account and parachain's total issuance.

[joepetrowski]

Yes, I agree

[gavofyork]

Yes, when FeeManager is used, they would be better sent to a proper account.

[gilescope]

Talking with Gav, it's best if the fees get accrued in the chain's treasury / a holding account rather than it going to collators. He said the only real question is the degree of aggregation:

1. No aggregation: use AssetTransactor directly in FeeManager.

2. Aggregate over XCVM execution: accrue in an XCVM MultiAssets (Holding-like) register and use AssetTransactor to disperse assets at the end of the XCVM execution.

3. Aggregate over block: accrue in a temporary MultiAssets storage item in pallet-xcm and place assets into accounts via a permissionless transaction (a "task", in the new lexicon) and AssetTransactor.

4. Aggregate indefinitely: accrue in a permanent MultiAssets storage item in pallet-xcm and allow a specific XCM origin to call ClaimAsset to claim them.

Option 1 is the easiest to implement, so we will do that initially but the others should be implemented eventually.