fix: lint rules

.gas-snapshot

@@ -1,17 +1,18 @@
 RlnTest:test__Constants() (gas: 8619)
-RlnTest:test__InvalidRegistration__DuplicateCommitment(uint256) (runs: 1000, μ: 144113, ~: 144113)
-RlnTest:test__InvalidRegistration__FullSet() (gas: 1433224)
-RlnTest:test__InvalidRegistration__InsufficientDeposit(uint256) (runs: 1000, μ: 17440, ~: 17440)
-RlnTest:test__InvalidRegistration__InvalidIdCommitment(uint256) (runs: 1000, μ: 17053, ~: 17058)
-RlnTest:test__InvalidRegistration__InvalidUserMessageLimit() (gas: 17055)
-RlnTest:test__InvalidRegistration__MaxUserMessageLimit() (gas: 17203)
-RlnTest:test__InvalidSlash__InvalidProof() (gas: 1081919)
-RlnTest:test__InvalidSlash__MemberNotRegistered(uint256) (runs: 1000, μ: 32521, ~: 32521)
-RlnTest:test__InvalidSlash__NoStake(uint256,address) (runs: 1000, μ: 319630, ~: 319682)
-RlnTest:test__InvalidSlash__ToRlnAddress() (gas: 151034)
-RlnTest:test__InvalidSlash__ToZeroAddress() (gas: 150939)
-RlnTest:test__InvalidWithdraw__InsufficientContractBalance() (gas: 145224)
+RlnTest:test__InvalidRegistration__DuplicateCommitment(uint256) (runs: 1000, μ: 144283, ~: 144283)
+RlnTest:test__InvalidRegistration__FullSet() (gas: 1576547)
+RlnTest:test__InvalidRegistration__InsufficientDeposit(uint256) (runs: 1000, μ: 17525, ~: 17525)
+RlnTest:test__InvalidRegistration__InvalidIdCommitment(uint256) (runs: 1000, μ: 17098, ~: 17103)
+RlnTest:test__InvalidRegistration__InvalidUserMessageLimit() (gas: 17100)
+RlnTest:test__InvalidRegistration__MaxUserMessageLimit() (gas: 17248)
+RlnTest:test__InvalidSlash__InvalidProof() (gas: 1224746)
+RlnTest:test__InvalidSlash__MemberNotRegistered(uint256) (runs: 1000, μ: 30343, ~: 30343)
+RlnTest:test__InvalidSlash__NoStake(uint256,address) (runs: 1000, μ: 319489, ~: 319497)
+RlnTest:test__InvalidSlash__ToRlnAddress() (gas: 151119)
+RlnTest:test__InvalidSlash__ToZeroAddress() (gas: 151024)
+RlnTest:test__InvalidWithdraw__InsufficientContractBalance() (gas: 145148)
 RlnTest:test__InvalidWithdraw__InsufficientWithdrawalBalance() (gas: 10538)
-RlnTest:test__ValidRegistration(uint256) (runs: 1000, μ: 135760, ~: 135760)
-RlnTest:test__ValidSlash(uint256,address) (runs: 1000, μ: 203402, ~: 203412)
-RlnTest:test__ValidWithdraw(address) (runs: 1000, μ: 202120, ~: 202108)
+RlnTest:test__ValidRegistration(uint256) (runs: 1000, μ: 135845, ~: 135845)
+RlnTest:test__ValidSlash(uint256,address) (runs: 1000, μ: 203288, ~: 203297)
+RlnTest:test__ValidWithdraw(address) (runs: 1000, μ: 202042, ~: 202032)
+RlnTest:test__root() (gas: 8178268)

src/BinaryIMTMemory.sol

@@ -1,9 +1,10 @@
 // SPDX-License-Identifier: MIT
-pragma solidity ^0.8.4;
+pragma solidity ^0.8.19;
 
 import { PoseidonT3 } from "poseidon-solidity/PoseidonT3.sol";
 
 // stripped down version of
+// solhint-disable-next-line max-line-length
 // https://github.com/privacy-scaling-explorations/zk-kit/blob/718a5c2fa0f6cd577cee3fd08373609ac985d3bb/packages/imt.sol/contracts/internal/InternalBinaryIMT.sol
 // that allows getting the root of the rln tree without expensive storage reads/writes
 struct BinaryIMTMemoryData {
@@ -61,6 +62,7 @@ library BinaryIMTMemory {
     uint256 public constant Z_20 =
         15_019_797_232_609_675_441_998_260_052_101_280_400_536_945_603_062_888_308_240_081_994_073_687_793_470;
 
+    // solhint-disable-next-line code-complexity
     function defaultZero(uint256 index) public pure returns (uint256) {
         if (index == 0) return Z_0;
         if (index == 1) return Z_1;