Fix gas cost in collective precompile (#3540)

* Fix gas cost in collective precompile

Author: RomarQ

precompiles/collective/src/lib.rs

@@ -18,7 +18,7 @@
 
 #![cfg_attr(not(feature = "std"), no_std)]
 
-use account::SYSTEM_ACCOUNT_SIZE;
+use account::{AccountId20, SYSTEM_ACCOUNT_SIZE};
 use core::marker::PhantomData;
 use fp_evm::Log;
 use frame_support::{
@@ -28,7 +28,7 @@ use frame_support::{
 	weights::Weight,
 };
 use pallet_evm::AddressMapping;
-use parity_scale_codec::DecodeLimit as _;
+use parity_scale_codec::{DecodeLimit as _, MaxEncodedLen};
 use precompile_utils::prelude::*;
 use sp_core::{Decode, Get, H160, H256};
 use sp_runtime::traits::Dispatchable;
@@ -310,9 +310,11 @@ where
 	#[precompile::public("members()")]
 	#[precompile::view]
 	fn members(handle: &mut impl PrecompileHandle) -> EvmResult<Vec<Address>> {
-		// Members: Vec(20 * MaxMembers)
+		// Record cost of reading the Members storage item, which contains up to MaxMembers accounts
+		// Cost: AccountId20 size × MaxMembers
 		handle.record_db_read::<Runtime>(
-			20 * (<Runtime as pallet_collective::Config<Instance>>::MaxProposals::get() as usize),
+			AccountId20::max_encoded_len()
+				* (<Runtime as pallet_collective::Config<Instance>>::MaxMembers::get() as usize),
 		)?;
 
 		let members = pallet_collective::Members::<Runtime, Instance>::get();
@@ -324,9 +326,11 @@ where
 	#[precompile::public("isMember(address)")]
 	#[precompile::view]
 	fn is_member(handle: &mut impl PrecompileHandle, account: Address) -> EvmResult<bool> {
-		// Members: Vec(20 * MaxMembers)
+		// Record cost of reading the Members storage item, which contains up to MaxMembers accounts
+		// Cost: AccountId20 size × MaxMembers
 		handle.record_db_read::<Runtime>(
-			20 * (<Runtime as pallet_collective::Config<Instance>>::MaxProposals::get() as usize),
+			AccountId20::max_encoded_len()
+				* (<Runtime as pallet_collective::Config<Instance>>::MaxMembers::get() as usize),
 		)?;
 
 		let account = Runtime::AddressMapping::into_account_id(account.into());