implement IERC20Metadata for pallet-assets-precompiles

prdoc/10971.prdoc

@@ -0,0 +1,27 @@
+title: "Implement IERC20Metadata for pallet-assets precompiles"
+
+doc:
+  - audience: Runtime Dev
+    description: |
+      Implements the missing ERC20 metadata functions (`name`, `symbol`, `decimals`) for the
+      pallet-assets precompile to provide full ERC20 compatibility. These functions are essential
+      for proper EVM wallet and tooling integration.
+
+      The precompile implementation reads metadata from pallet-assets storage and returns properly
+      formatted values with appropriate gas charging using dedicated weight functions. All functions
+      include proper error handling for missing metadata and invalid UTF-8 encoding.
+
+      Benchmarks have been added to measure the weight of metadata reads, and corresponding weight
+      functions have been implemented in the WeightInfo trait.
+
+      The IERC20.sol interface file has been reorganized to clearly separate and document methods
+      from the base IERC20 interface and the IERC20Metadata extension, with links to the original
+      OpenZeppelin contracts for better maintainability.
+
+crates:
+  - name: ethereum-standards
+    bump: minor
+  - name: pallet-assets-precompiles
+    bump: minor
+  - name: pallet-assets
+    bump: minor

substrate/frame/assets/precompiles/src/lib.rs

@@ -118,6 +118,9 @@ where
 			IERC20Calls::allowance(call) => Self::allowance(asset_id, call, env),
 			IERC20Calls::approve(call) => Self::approve(asset_id, call, env),
 			IERC20Calls::transferFrom(call) => Self::transfer_from(asset_id, call, env),
+			IERC20Calls::name(_) => Self::name(asset_id, env),
+			IERC20Calls::symbol(_) => Self::symbol(asset_id, env),
+			IERC20Calls::decimals(_) => Self::decimals(asset_id, env),
 		}
 	}
 }
@@ -322,4 +325,49 @@ where
 
 		return Ok(IERC20::transferFromCall::abi_encode_returns(&true));
 	}
+
+	/// Execute the name call.
+	fn name(
+		asset_id: <Runtime as Config<Instance>>::AssetId,
+		env: &mut impl Ext<T = Runtime>,
+	) -> Result<Vec<u8>, Error> {
+		env.charge(<Runtime as Config<Instance>>::WeightInfo::get_name())?;
+
+		let metadata = pallet_assets::Pallet::<Runtime, Instance>::get_metadata(asset_id)
+			.ok_or(Error::Revert(Revert { reason: "Metadata not found".into() }))?;
+
+		let name = alloc::string::String::from_utf8(metadata.name.to_vec())
+			.map_err(|_| Error::Revert(Revert { reason: "Invalid UTF-8 in name".into() }))?;
+
+		Ok(IERC20::nameCall::abi_encode_returns(&name))
+	}
+
+	/// Execute the symbol call.
+	fn symbol(
+		asset_id: <Runtime as Config<Instance>>::AssetId,
+		env: &mut impl Ext<T = Runtime>,
+	) -> Result<Vec<u8>, Error> {
+		env.charge(<Runtime as Config<Instance>>::WeightInfo::get_symbol())?;
+
+		let metadata = pallet_assets::Pallet::<Runtime, Instance>::get_metadata(asset_id)
+			.ok_or(Error::Revert(Revert { reason: "Metadata not found".into() }))?;
+
+		let symbol = alloc::string::String::from_utf8(metadata.symbol.to_vec())
+			.map_err(|_| Error::Revert(Revert { reason: "Invalid UTF-8 in symbol".into() }))?;
+
+		Ok(IERC20::symbolCall::abi_encode_returns(&symbol))
+	}
+
+	/// Execute the decimals call.
+	fn decimals(
+		asset_id: <Runtime as Config<Instance>>::AssetId,
+		env: &mut impl Ext<T = Runtime>,
+	) -> Result<Vec<u8>, Error> {
+		env.charge(<Runtime as Config<Instance>>::WeightInfo::get_decimals())?;
+
+		let metadata = pallet_assets::Pallet::<Runtime, Instance>::get_metadata(asset_id)
+			.ok_or(Error::Revert(Revert { reason: "Metadata not found".into() }))?;
+
+		Ok(IERC20::decimalsCall::abi_encode_returns(&metadata.decimals))
+	}
 }

substrate/frame/assets/src/benchmarking.rs

@@ -641,5 +641,50 @@ benchmarks_instance_pallet! {
 		assert_eq!(Reserves::<T, I>::get(id)[0], reserve);
 	}
 
+	get_name {
+		let (asset_id, caller, _) = create_default_asset::<T, I>(true);
+		T::Currency::make_free_balance_be(&caller, DepositBalanceOf::<T, I>::max_value());
+		let name_bytes = vec![0u8; T::StringLimit::get() as usize];
+		let symbol_bytes = vec![0u8; T::StringLimit::get() as usize];
+		let origin = SystemOrigin::Signed(caller).into();
+		Assets::<T, I>::set_metadata(origin, asset_id.clone(), name_bytes.clone(), symbol_bytes, 12)?;
+	}: {
+		let _ = Pallet::<T, I>::get_metadata(asset_id.clone().into());
+	} verify {
+		let metadata = Pallet::<T, I>::get_metadata(asset_id.into());
+		assert!(metadata.is_some());
+		assert_eq!(metadata.unwrap().name.to_vec(), name_bytes);
+	}
+
+	get_symbol {
+		let (asset_id, caller, _) = create_default_asset::<T, I>(true);
+		T::Currency::make_free_balance_be(&caller, DepositBalanceOf::<T, I>::max_value());
+		let name_bytes = vec![0u8; T::StringLimit::get() as usize];
+		let symbol_bytes = vec![0u8; T::StringLimit::get() as usize];
+		let origin = SystemOrigin::Signed(caller).into();
+		Assets::<T, I>::set_metadata(origin, asset_id.clone(), name_bytes, symbol_bytes.clone(), 12)?;
+	}: {
+		let _ = Pallet::<T, I>::get_metadata(asset_id.clone().into());
+	} verify {
+		let metadata = Pallet::<T, I>::get_metadata(asset_id.into());
+		assert!(metadata.is_some());
+		assert_eq!(metadata.unwrap().symbol.to_vec(), symbol_bytes);
+	}
+
+	get_decimals {
+		let (asset_id, caller, _) = create_default_asset::<T, I>(true);
+		T::Currency::make_free_balance_be(&caller, DepositBalanceOf::<T, I>::max_value());
+		let name_bytes = vec![0u8; T::StringLimit::get() as usize];
+		let symbol_bytes = vec![0u8; T::StringLimit::get() as usize];
+		let origin = SystemOrigin::Signed(caller).into();
+		Assets::<T, I>::set_metadata(origin, asset_id.clone(), name_bytes, symbol_bytes, 12)?;
+	}: {
+		let _ = Pallet::<T, I>::get_metadata(asset_id.clone().into());
+	} verify {
+		let metadata = Pallet::<T, I>::get_metadata(asset_id.into());
+		assert!(metadata.is_some());
+		assert_eq!(metadata.unwrap().decimals, 12);
+	}
+
 	impl_benchmark_test_suite!(Assets, crate::mock::new_test_ext(), crate::mock::Test)
 }