fix(xcm): remove waived locations (#456)

* fix(xcm): no locations are waived

* test(xcm): improved waived_location test

changes after rebase

* style(xcm): clarify that we are not waiving fees for any location

Author: al3mart

runtime/mainnet/src/config/xcm.rs

@@ -13,9 +13,7 @@ use frame_system::EnsureRoot;
 use pallet_xcm::XcmPassthrough;
 use parachains_common::{
 	message_queue::{NarrowOriginToSibling, ParaIdToSibling},
-	xcm_config::{
-		AllSiblingSystemParachains, ParentRelayOrSiblingParachains, RelayOrOtherSystemParachains,
-	},
+	xcm_config::ParentRelayOrSiblingParachains,
 };
 use polkadot_parachain_primitives::primitives::Sibling;
 use polkadot_runtime_common::xcm_sender::NoPriceForMessageDelivery;
@@ -156,11 +154,6 @@ impl<T: Get<Location>> Contains<(Location, Vec<Asset>)> for NativeAssetFrom<T> {
 /// Combinations of (Asset, Location) pairs which we trust as reserves.
 pub type TrustedReserves = NativeAssetFrom<AssetHub>;
 
-/// Locations that will not be charged fees in the executor,
-/// either execution or delivery.
-/// We only waive fees for system functions, which these locations represent.
-pub type WaivedLocations = (RelayOrOtherSystemParachains<AllSiblingSystemParachains, Runtime>,);
-
 parameter_types! {
 	// One XCM operation is 1_000_000_000 weight - almost certainly a conservative estimate.
 	pub UnitWeightCost: Weight = Weight::from_parts(1_000_000_000, 64 * 1024);
@@ -179,8 +172,9 @@ impl xcm_executor::Config for XcmConfig {
 	type AssetTrap = PolkadotXcm;
 	type Barrier = Barrier;
 	type CallDispatcher = RuntimeCall;
+	// No locations have waived fees.
 	type FeeManager = XcmFeeManagerFromComponents<
-		WaivedLocations,
+		(),
 		SendXcmFeeToAccount<Self::AssetTransactor, TreasuryAccount>,
 	>;
 	type HrmpChannelAcceptedHandler = ();
@@ -278,6 +272,8 @@ impl cumulus_pallet_xcmp_queue::Config for Runtime {
 mod tests {
 	use std::any::TypeId;
 
+	use xcm_executor::traits::{FeeManager, FeeReason};
+
 	use super::*;
 
 	mod reserves_config {
@@ -563,7 +559,7 @@ mod tests {
 				TypeId::of::<<XcmConfig as xcm_executor::Config>::FeeManager>(),
 				TypeId::of::<
 					XcmFeeManagerFromComponents<
-						WaivedLocations,
+						(),
 						SendXcmFeeToAccount<
 							<XcmConfig as xcm_executor::Config>::AssetTransactor,
 							TreasuryAccount,
@@ -573,6 +569,26 @@ mod tests {
 			);
 		}
 
+		#[test]
+		fn no_locations_are_waived() {
+			let locations = [
+				Location::here(),
+				Location::parent(),
+				Location::new(1, [Parachain(1000)]),
+				Location::new(1, [Parachain(1000), PalletInstance(50), GeneralIndex(1984)]),
+				Location::new(
+					1,
+					[Parachain(1000), AccountId32 { network: None, id: Default::default() }],
+				),
+			];
+			for location in locations {
+				assert!(!<<XcmConfig as xcm_executor::Config>::FeeManager>::is_waived(
+					Some(&location),
+					FeeReason::TransferReserveAsset
+				));
+			}
+		}
+
 		#[test]
 		fn hrmp_accepted_handler_is_disabled() {
 			assert_eq!(