Add Solhint solidity linter (#240)

* Add solhint and prettier for solidity
* Apply prettier styles on contracts
* Fix solhint warnings
* Run js and solidity linter on travis

.prettierrc

@@ -1,5 +1,6 @@
 {
   "semi": false,
   "singleQuote": true,
-  "printWidth": 120
+  "printWidth": 120,
+  "bracketSpacing": true
 }

.solhint.json

@@ -0,0 +1,13 @@
+{
+  "extends": "solhint:recommended",
+  "plugins": ["prettier"],
+  "rules": {
+    "prettier/prettier": "error",
+    "mark-callable-contracts": "off",
+    "avoid-low-level-calls": "off",
+    "no-inline-assembly": "off",
+    "multiple-sends": "off",
+    "bracket-align": "off",
+    "compiler-version": ["error", "0.4.24"]
+  }
+}

.travis.yml

@@ -10,5 +10,5 @@ env:
   - SOLIDITY_COVERAGE=false
   - SOLIDITY_COVERAGE=true
 script:
-  - yarn lint:js
+  - yarn lint
   - yarn test

contracts/ERC677BridgeToken.sol

@@ -6,24 +6,16 @@ import "openzeppelin-solidity/contracts/token/ERC20/DetailedERC20.sol";
 import "./interfaces/IBurnableMintableERC677Token.sol";
 import "./upgradeable_contracts/Claimable.sol";
 
-contract ERC677BridgeToken is
-    IBurnableMintableERC677Token,
-    DetailedERC20,
-    BurnableToken,
-    MintableToken,
-    Claimable {
-
+contract ERC677BridgeToken is IBurnableMintableERC677Token, DetailedERC20, BurnableToken, MintableToken, Claimable {
     address public bridgeContract;
 
-    event ContractFallbackCallFailed(address from, address to, uint value);
+    event ContractFallbackCallFailed(address from, address to, uint256 value);
 
-    constructor(
-        string _name,
-        string _symbol,
-        uint8 _decimals)
-    public DetailedERC20(_name, _symbol, _decimals) {}
+    constructor(string _name, string _symbol, uint8 _decimals) public DetailedERC20(_name, _symbol, _decimals) {
+        // solhint-disable-previous-line no-empty-blocks
+    }
 
-    function setBridgeContract(address _bridgeContract) onlyOwner external {
+    function setBridgeContract(address _bridgeContract) external onlyOwner {
         require(isContract(_bridgeContract));
         bridgeContract = _bridgeContract;
     }
@@ -33,9 +25,7 @@ contract ERC677BridgeToken is
         _;
     }
 
-    function transferAndCall(address _to, uint _value, bytes _data)
-        external validRecipient(_to) returns (bool)
-    {
+    function transferAndCall(address _to, uint256 _value, bytes _data) external validRecipient(_to) returns (bool) {
         require(superTransfer(_to, _value));
         emit Transfer(msg.sender, _to, _value, _data);
 
@@ -45,17 +35,15 @@ contract ERC677BridgeToken is
         return true;
     }
 
-    function getTokenInterfacesVersion() external pure returns(uint64 major, uint64 minor, uint64 patch) {
+    function getTokenInterfacesVersion() external pure returns (uint64 major, uint64 minor, uint64 patch) {
         return (2, 1, 0);
     }
 
-    function superTransfer(address _to, uint256 _value) internal returns(bool)
-    {
+    function superTransfer(address _to, uint256 _value) internal returns (bool) {
         return super.transfer(_to, _value);
     }
 
-    function transfer(address _to, uint256 _value) public returns (bool)
-    {
+    function transfer(address _to, uint256 _value) public returns (bool) {
         require(superTransfer(_to, _value));
         callAfterTransfer(msg.sender, _to, _value);
         return true;
@@ -74,17 +62,15 @@ contract ERC677BridgeToken is
         }
     }
 
-    function contractFallback(address _from, address _to, uint _value, bytes _data) private returns(bool) {
-        return _to.call(abi.encodeWithSignature("onTokenTransfer(address,uint256,bytes)",  _from, _value, _data));
+    function contractFallback(address _from, address _to, uint256 _value, bytes _data) private returns (bool) {
+        return _to.call(abi.encodeWithSignature("onTokenTransfer(address,uint256,bytes)", _from, _value, _data));
     }
 
-    function isContract(address _addr)
-        internal
-        view
-        returns (bool)
-    {
-        uint length;
-        assembly { length := extcodesize(_addr) }
+    function isContract(address _addr) internal view returns (bool) {
+        uint256 length;
+        assembly {
+            length := extcodesize(_addr)
+        }
         return length > 0;
     }
 

contracts/ERC677BridgeTokenRewardable.sol

@@ -2,24 +2,20 @@ pragma solidity 0.4.24;
 
 import "./ERC677BridgeToken.sol";
 
-
 contract ERC677BridgeTokenRewardable is ERC677BridgeToken {
-
     address public blockRewardContract;
     address public stakingContract;
 
-    constructor(
-        string _name,
-        string _symbol,
-        uint8 _decimals
-    ) public ERC677BridgeToken(_name, _symbol, _decimals) {}
+    constructor(string _name, string _symbol, uint8 _decimals) public ERC677BridgeToken(_name, _symbol, _decimals) {
+        // solhint-disable-previous-line no-empty-blocks
+    }
 
-    function setBlockRewardContract(address _blockRewardContract) onlyOwner external {
+    function setBlockRewardContract(address _blockRewardContract) external onlyOwner {
         require(isContract(_blockRewardContract));
         blockRewardContract = _blockRewardContract;
     }
 
-    function setStakingContract(address _stakingContract) onlyOwner external {
+    function setStakingContract(address _stakingContract) external onlyOwner {
         require(isContract(_stakingContract));
         stakingContract = _stakingContract;
     }
@@ -66,12 +62,12 @@ contract ERC677BridgeTokenRewardable is ERC677BridgeToken {
         emit Transfer(stakingContract, _staker, _amount);
     }
 
-    function transfer(address _to, uint256 _value) public returns(bool) {
+    function transfer(address _to, uint256 _value) public returns (bool) {
         require(_to != stakingContract);
         return super.transfer(_to, _value);
     }
 
-    function transferFrom(address _from, address _to, uint256 _value) public returns(bool) {
+    function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
         require(_to != stakingContract);
         return super.transferFrom(_from, _to, _value);
     }

contracts/Migrations.sol

@@ -1,23 +1,24 @@
 pragma solidity 0.4.24;
 
 contract Migrations {
-  address public owner;
-  uint public last_completed_migration;
+    address public owner;
+    // solhint-disable-next-line var-name-mixedcase
+    uint256 public last_completed_migration;
 
-  modifier restricted() {
-    if (msg.sender == owner) _;
-  }
+    modifier restricted() {
+        if (msg.sender == owner) _;
+    }
 
-  constructor() public {
-    owner = msg.sender;
-  }
+    constructor() public {
+        owner = msg.sender;
+    }
 
-  function setCompleted(uint completed) public restricted {
-    last_completed_migration = completed;
-  }
+    function setCompleted(uint256 completed) public restricted {
+        last_completed_migration = completed;
+    }
 
-  function upgrade(address new_address) public restricted {
-    Migrations upgraded = Migrations(new_address);
-    upgraded.setCompleted(last_completed_migration);
-  }
+    function upgrade(address new_address) public restricted {
+        Migrations upgraded = Migrations(new_address);
+        upgraded.setCompleted(last_completed_migration);
+    }
 }

contracts/interfaces/ERC677.sol

@@ -1,10 +1,9 @@
 pragma solidity 0.4.24;
 import "openzeppelin-solidity/contracts/token/ERC20/ERC20.sol";
 
-
 contract ERC677 is ERC20 {
-    event Transfer(address indexed from, address indexed to, uint value, bytes data);
+    event Transfer(address indexed from, address indexed to, uint256 value, bytes data);
 
-    function transferAndCall(address, uint, bytes) external returns (bool);
+    function transferAndCall(address, uint256, bytes) external returns (bool);
 
 }

contracts/interfaces/ERC677Receiver.sol

@@ -1,6 +1,5 @@
 pragma solidity 0.4.24;
 
-
 contract ERC677Receiver {
-  function onTokenTransfer(address _from, uint _value, bytes _data) external returns(bool);
+    function onTokenTransfer(address _from, uint256 _value, bytes _data) external returns (bool);
 }

contracts/interfaces/IBlockReward.sol

@@ -1,12 +1,11 @@
 pragma solidity 0.4.24;
 
-
 interface IBlockReward {
     function addExtraReceiver(uint256 _amount, address _receiver) external;
     function mintedTotally() external view returns (uint256);
-    function mintedTotallyByBridge(address _bridge) external view returns(uint256);
-    function bridgesAllowedLength() external view returns(uint256);
+    function mintedTotallyByBridge(address _bridge) external view returns (uint256);
+    function bridgesAllowedLength() external view returns (uint256);
     function addBridgeTokenFeeReceivers(uint256 _amount) external;
     function addBridgeNativeFeeReceivers(uint256 _amount) external;
-    function blockRewardContractId() external pure returns(bytes4);
+    function blockRewardContractId() external pure returns (bytes4);
 }

contracts/interfaces/IBridgeValidators.sol

@@ -1,8 +1,7 @@
 pragma solidity 0.4.24;
 
-
 interface IBridgeValidators {
-    function isValidator(address _validator) external view returns(bool);
-    function requiredSignatures() external view returns(uint256);
-    function owner() external view returns(address);
+    function isValidator(address _validator) external view returns (bool);
+    function requiredSignatures() external view returns (uint256);
+    function owner() external view returns (address);
 }

contracts/interfaces/IBurnableMintableERC677Token.sol

@@ -1,7 +1,6 @@
 pragma solidity 0.4.24;
 import "../interfaces/ERC677.sol";
 
-
 contract IBurnableMintableERC677Token is ERC677 {
     function mint(address, uint256) public returns (bool);
     function burn(uint256 _value) public;

contracts/interfaces/IRewardableValidators.sol

@@ -1,12 +1,11 @@
 pragma solidity 0.4.24;
 
-
 interface IRewardableValidators {
-    function isValidator(address _validator) external view returns(bool);
-    function requiredSignatures() external view returns(uint256);
-    function owner() external view returns(address);
+    function isValidator(address _validator) external view returns (bool);
+    function requiredSignatures() external view returns (uint256);
+    function owner() external view returns (address);
     function validatorList() external view returns (address[]);
-    function getValidatorRewardAddress(address _validator) external view returns(address);
+    function getValidatorRewardAddress(address _validator) external view returns (address);
     function validatorCount() external view returns (uint256);
     function getNextValidator(address _address) external view returns (address);
 }

contracts/interfaces/IUpgradeabilityOwnerStorage.sol

@@ -1,6 +1,5 @@
 pragma solidity 0.4.24;
 
-
 interface IUpgradeabilityOwnerStorage {
     function upgradeabilityOwner() external view returns (address);
 }

contracts/libraries/Message.sol

@@ -1,7 +1,6 @@
 pragma solidity 0.4.24;
 import "../interfaces/IBridgeValidators.sol";
 
-
 library Message {
     // function uintToString(uint256 inputValue) internal pure returns (string) {
     //     // figure out the length of the resulting string
@@ -50,7 +49,7 @@ library Message {
     function parseMessage(bytes message)
         internal
         pure
-        returns(address recipient, uint256 amount, bytes32 txHash, address contractAddress)
+        returns (address recipient, uint256 amount, bytes32 txHash, address contractAddress)
     {
         require(isMessageValid(message));
         assembly {
@@ -61,11 +60,11 @@ library Message {
         }
     }
 
-    function isMessageValid(bytes _msg) internal pure returns(bool) {
+    function isMessageValid(bytes _msg) internal pure returns (bool) {
         return _msg.length == requiredMessageLength();
     }
 
-    function requiredMessageLength() internal pure returns(uint256) {
+    function requiredMessageLength() internal pure returns (uint256) {
         return 104;
     }
 
@@ -94,7 +93,8 @@ library Message {
         uint8[] _vs,
         bytes32[] _rs,
         bytes32[] _ss,
-        IBridgeValidators _validatorContract) internal view {
+        IBridgeValidators _validatorContract
+    ) internal view {
         require(isMessageValid(_message));
         uint256 requiredSignatures = _validatorContract.requiredSignatures();
         // It is not necessary to check that arrays have the same length since it will be handled

contracts/test/BlockReward.sol

@@ -3,7 +3,6 @@ pragma solidity 0.4.24;
 import "../interfaces/IBlockReward.sol";
 import "openzeppelin-solidity/contracts/math/SafeMath.sol";
 
-
 contract BlockReward {
     using SafeMath for uint256;
 
@@ -14,7 +13,8 @@ contract BlockReward {
     bytes32 internal constant MINTED_TOTALLY_BY_BRIDGE = "mintedTotallyByBridge";
     address public token;
 
-    function () external payable {
+    function() external payable {
+        // solhint-disable-previous-line no-empty-blocks
     }
 
     function addExtraReceiver(uint256 _amount, address _receiver) external {
@@ -29,10 +29,8 @@ contract BlockReward {
         return mintedCoins;
     }
 
-    function mintedTotallyByBridge(address _bridge) public view returns(uint256) {
-        return uintStorage[
-        keccak256(abi.encode(MINTED_TOTALLY_BY_BRIDGE, _bridge))
-        ];
+    function mintedTotallyByBridge(address _bridge) public view returns (uint256) {
+        return uintStorage[keccak256(abi.encode(MINTED_TOTALLY_BY_BRIDGE, _bridge))];
     }
 
     function addMintedTotallyByBridge(uint256 _amount, address _bridge) external {
@@ -91,11 +89,11 @@ contract BlockReward {
         require(token.call(abi.encodeWithSignature("mintReward(address[],uint256[])", receivers, rewards)));
     }
 
-    function random(uint256 _count) public view returns(uint256) {
+    function random(uint256 _count) public view returns (uint256) {
         return uint256(blockhash(block.number.sub(1))) % _count;
     }
 
-    function blockRewardContractId() public pure returns(bytes4) {
+    function blockRewardContractId() public pure returns (bytes4) {
         return bytes4(keccak256("blockReward"));
     }
 }

contracts/test/Staking.sol

@@ -1,6 +1,7 @@
 pragma solidity 0.4.24;
 
-
 contract Staking {
-    constructor() public {}
+    constructor() public {
+        // solhint-disable-previous-line no-empty-blocks
+    }
 }