Drop ED Requirement for Transaction Payment with Exchangeable Asset #310
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muharem
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YES PLEASE |
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tests? |
tests for these types are passing here - paritytech/polkadot-sdk#4455 |
| match T::Assets::settle(who, debt, Preservation::Expendable) { | ||
| Ok(dust) => ensure!( | ||
| dust.peek() == Zero::zero(), | ||
| InvalidTransaction::Payment |
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Debugging this will be fund, as it always returns InvalidTransaction::Payment 🙃 maybe some logs?
I did address your comments. Also if these functions errors, the extrinsic is invalid, these methods used by validate, pre_dispatch, and post_dispatch. I have also updated the PR with tests, to have the exact same types as in this PR with the last changes, the tests are green (paritytech/polkadot-sdk#4455). |
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/merge |
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Drop the Existential Deposit (ED) requirement for the asset amount exchangeable for the fee asset (DOT/KSM) during transaction payments.
Currently, every swap during transaction payment, processed with asset
Afor native asset, must be for an amount greater than the ED of a native asset if the user lacks a native asset account. Since fees are typically smaller, the current implementation necessitates additional swaps to meet the ED duringpre_dispatch, with refunds for excess ED swap occurring duringpost_dispatch. Further details can be found here.This setup presents an issue where a user is unable to transfer their entire balance and close the account. Instead, the user must transfer slightly less of asset
Ato ensure there is enough not only for the fee payment but also some extra to meet the ED requirement for their native account duringpre_dispatch. In some cases duringpost_dispatch, the user will have the excess ED swapped back to assetA, while in other cases, it may not be sufficient to meet the ED requirement for assetA, leading it being left in the user's 'temporary' native asset account.Example: https://assethub-polkadot.subscan.io/extrinsic/6204018-9?event=6204018-79
Given the importance of this scenario for CEX, I propose a solution that does not entail breaking changes to the pallets' API and open PR to the runtimes without waiting for new polkadot-sdk version. Additionally, I have opened a draft PR with these types in their respective pallets in FRAME, where they have been tested against existing tests for types implementing the same contract. PR - paritytech/polkadot-sdk#4455
Target implementation with breaking changes: paritytech/polkadot-sdk#4488