Fee and tip represented as asset ID inside AssetTxFeePaid (paritytech#13083)

* fee & tip in the asset ID Balance type

* docs

* rewrite

* update runtime config

* docs

Author: Szegoo

frame/transaction-payment/asset-tx-payment/src/lib.rs

@@ -134,8 +134,8 @@ pub mod pallet {
 		/// has been paid by `who` in an asset `asset_id`.
 		AssetTxFeePaid {
 			who: T::AccountId,
-			actual_fee: BalanceOf<T>,
-			tip: BalanceOf<T>,
+			actual_fee: AssetBalanceOf<T>,
+			tip: AssetBalanceOf<T>,
 			asset_id: Option<ChargeAssetIdOf<T>>,
 		},
 	}
@@ -284,18 +284,20 @@ where
 					let actual_fee = pallet_transaction_payment::Pallet::<T>::compute_actual_fee(
 						len as u32, info, post_info, tip,
 					);
-					T::OnChargeAssetTransaction::correct_and_deposit_fee(
-						&who,
-						info,
-						post_info,
-						actual_fee.into(),
-						tip.into(),
-						already_withdrawn.into(),
-					)?;
+
+					let (converted_fee, converted_tip) =
+						T::OnChargeAssetTransaction::correct_and_deposit_fee(
+							&who,
+							info,
+							post_info,
+							actual_fee.into(),
+							tip.into(),
+							already_withdrawn.into(),
+						)?;
 					Pallet::<T>::deposit_event(Event::<T>::AssetTxFeePaid {
 						who,
-						actual_fee,
-						tip,
+						actual_fee: converted_fee,
+						tip: converted_tip,
 						asset_id,
 					});
 				},

frame/transaction-payment/asset-tx-payment/src/payment.rs

@@ -58,14 +58,16 @@ pub trait OnChargeAssetTransaction<T: Config> {
 	/// the corrected amount.
 	///
 	/// Note: The `fee` already includes the `tip`.
+	///
+	/// Returns the fee and tip in the asset used for payment as (fee, tip).
 	fn correct_and_deposit_fee(
 		who: &T::AccountId,
 		dispatch_info: &DispatchInfoOf<T::RuntimeCall>,
 		post_info: &PostDispatchInfoOf<T::RuntimeCall>,
 		corrected_fee: Self::Balance,
 		tip: Self::Balance,
 		already_withdrawn: Self::LiquidityInfo,
-	) -> Result<(), TransactionValidityError>;
+	) -> Result<(AssetBalanceOf<T>, AssetBalanceOf<T>), TransactionValidityError>;
 }
 
 /// Allows specifying what to do with the withdrawn asset fees.
@@ -132,26 +134,31 @@ where
 	/// Since the predicted fee might have been too high, parts of the fee may be refunded.
 	///
 	/// Note: The `corrected_fee` already includes the `tip`.
+	///
+	/// Returns the fee and tip in the asset used for payment as (fee, tip).
 	fn correct_and_deposit_fee(
 		who: &T::AccountId,
 		_dispatch_info: &DispatchInfoOf<T::RuntimeCall>,
 		_post_info: &PostDispatchInfoOf<T::RuntimeCall>,
 		corrected_fee: Self::Balance,
-		_tip: Self::Balance,
+		tip: Self::Balance,
 		paid: Self::LiquidityInfo,
-	) -> Result<(), TransactionValidityError> {
+	) -> Result<(AssetBalanceOf<T>, AssetBalanceOf<T>), TransactionValidityError> {
 		let min_converted_fee = if corrected_fee.is_zero() { Zero::zero() } else { One::one() };
-		// Convert the corrected fee into the asset used for payment.
+		// Convert the corrected fee and tip into the asset used for payment.
 		let converted_fee = CON::to_asset_balance(corrected_fee, paid.asset())
 			.map_err(|_| -> TransactionValidityError { InvalidTransaction::Payment.into() })?
 			.max(min_converted_fee);
+		let converted_tip = CON::to_asset_balance(tip, paid.asset())
+			.map_err(|_| -> TransactionValidityError { InvalidTransaction::Payment.into() })?;
+
 		// Calculate how much refund we should return.
 		let (final_fee, refund) = paid.split(converted_fee);
 		// Refund to the account that paid the fees. If this fails, the account might have dropped
 		// below the existential balance. In that case we don't refund anything.
 		let _ = <T::Fungibles as Balanced<T::AccountId>>::resolve(who, refund);
 		// Handle the final fee, e.g. by transferring to the block author or burning.
 		HC::handle_credit(final_fee);
-		Ok(())
+		Ok((converted_fee, converted_tip))
 	}
 }