1

I have two questions. My contract has compiled and deployed successfully both using remix and truffle. However: q1) remix returns an empty array of ABI.

enter image description here

Also, after I hit compile the contract at the bottom left changes back to Context.sol instead of ww1.sol.

enter image description here

q2) in Truffle, the contract's json file in build/contracts/ folder has the abi which is below:

[{ "anonymous": false, "inputs": [ { "indexed": true, "internalType": "address", "name": "owner", "type": "address" }, { "indexed": true, "internalType": "address", "name": "spender", "type": "address" }, { "indexed": false, "internalType": "uint256", "name": "value", "type": "uint256" } ], "name": "Approval", "type": "event" }, { "anonymous": false, "inputs": [ { "indexed": true, "internalType": "address", "name": "delegator", "type": "address" }, { "indexed": true, "internalType": "address", "name": "fromDelegate", "type": "address" }, { "indexed": true, "internalType": "address", "name": "toDelegate", "type": "address" } ], "name": "DelegateChanged", "type": "event" }, { "anonymous": false, "inputs": [ { "indexed": true, "internalType": "address", "name": "delegate", "type": "address" }, { "indexed": false, "internalType": "uint256", "name": "previousBalance", "type": "uint256" }, { "indexed": false, "internalType": "uint256", "name": "newBalance", "type": "uint256" } ], "name": "DelegateVotesChanged", "type": "event" }, { "anonymous": false, "inputs": [ { "indexed": true, "internalType": "address", "name": "previousOwner", "type": "address" }, { "indexed": true, "internalType": "address", "name": "newOwner", "type": "address" } ], "name": "OwnershipTransferred", "type": "event" }, { "anonymous": false, "inputs": [ { "indexed": true, "internalType": "address", "name": "from", "type": "address" }, { "indexed": true, "internalType": "address", "name": "to", "type": "address" }, { "indexed": false, "internalType": "uint256", "name": "value", "type": "uint256" } ], "name": "Transfer", "type": "event" }, { "inputs": [], "name": "DELEGATION_TYPEHASH", "outputs": [ { "internalType": "bytes32", "name": "", "type": "bytes32" } ], "stateMutability": "view", "type": "function", "constant": true }, { "inputs": [], "name": "DOMAIN_TYPEHASH", "outputs": [ { "internalType": "bytes32", "name": "", "type": "bytes32" } ], "stateMutability": "view", "type": "function", "constant": true }, { "inputs": [ { "internalType": "address", "name": "owner", "type": "address" }, { "internalType": "address", "name": "spender", "type": "address" } ], "name": "allowance", "outputs": [ { "internalType": "uint256", "name": "", "type": "uint256" } ], "stateMutability": "view", "type": "function", "constant": true }, { "inputs": [ { "internalType": "address", "name": "spender", "type": "address" }, { "internalType": "uint256", "name": "amount", "type": "uint256" } ], "name": "approve", "outputs": [ { "internalType": "bool", "name": "", "type": "bool" } ], "stateMutability": "nonpayable", "type": "function" }, { "inputs": [ { "internalType": "address", "name": "account", "type": "address" } ], "name": "balanceOf", "outputs": [ { "internalType": "uint256", "name": "", "type": "uint256" } ], "stateMutability": "view", "type": "function", "constant": true }, { "inputs": [ { "internalType": "address", "name": "", "type": "address" }, { "internalType": "uint32", "name": "", "type": "uint32" } ], "name": "checkpoints", "outputs": [ { "internalType": "uint32", "name": "fromBlock", "type": "uint32" }, { "internalType": "uint256", "name": "votes", "type": "uint256" } ], "stateMutability": "view", "type": "function", "constant": true }, { "inputs": [], "name": "decimals", "outputs": [ { "internalType": "uint8", "name": "", "type": "uint8" } ], "stateMutability": "view", "type": "function", "constant": true }, { "inputs": [ { "internalType": "address", "name": "spender", "type": "address" }, { "internalType": "uint256", "name": "subtractedValue", "type": "uint256" } ], "name": "decreaseAllowance", "outputs": [ { "internalType": "bool", "name": "", "type": "bool" } ], "stateMutability": "nonpayable", "type": "function" }, { "inputs": [], "name": "getOwner", "outputs": [ { "internalType": "address", "name": "", "type": "address" } ], "stateMutability": "view", "type": "function", "constant": true }, { "inputs": [ { "internalType": "address", "name": "spender", "type": "address" }, { "internalType": "uint256", "name": "addedValue", "type": "uint256" } ], "name": "increaseAllowance", "outputs": [ { "internalType": "bool", "name": "", "type": "bool" } ], "stateMutability": "nonpayable", "type": "function" }, { "inputs": [], "name": "name", "outputs": [ { "internalType": "string", "name": "", "type": "string" } ], "stateMutability": "view", "type": "function", "constant": true }, { "inputs": [ { "internalType": "address", "name": "", "type": "address" } ], "name": "nonces", "outputs": [ { "internalType": "uint256", "name": "", "type": "uint256" } ], "stateMutability": "view", "type": "function", "constant": true }, { "inputs": [ { "internalType": "address", "name": "", "type": "address" } ], "name": "numCheckpoints", "outputs": [ { "internalType": "uint32", "name": "", "type": "uint32" } ], "stateMutability": "view", "type": "function", "constant": true }, { "inputs": [], "name": "owner", "outputs": [ { "internalType": "address", "name": "", "type": "address" } ], "stateMutability": "view", "type": "function", "constant": true }, { "inputs": [], "name": "renounceOwnership", "outputs": [], "stateMutability": "nonpayable", "type": "function" }, { "inputs": [], "name": "symbol", "outputs": [ { "internalType": "string", "name": "", "type": "string" } ], "stateMutability": "view", "type": "function", "constant": true }, { "inputs": [], "name": "totalSupply", "outputs": [ { "internalType": "uint256", "name": "", "type": "uint256" } ], "stateMutability": "view", "type": "function", "constant": true }, { "inputs": [ { "internalType": "address", "name": "recipient", "type": "address" }, { "internalType": "uint256", "name": "amount", "type": "uint256" } ], "name": "transfer", "outputs": [ { "internalType": "bool", "name": "", "type": "bool" } ], "stateMutability": "nonpayable", "type": "function" }, { "inputs": [ { "internalType": "address", "name": "sender", "type": "address" }, { "internalType": "address", "name": "recipient", "type": "address" }, { "internalType": "uint256", "name": "amount", "type": "uint256" } ], "name": "transferFrom", "outputs": [ { "internalType": "bool", "name": "", "type": "bool" } ], "stateMutability": "nonpayable", "type": "function" }, { "inputs": [ { "internalType": "address", "name": "newOwner", "type": "address" } ], "name": "transferOwnership", "outputs": [], "stateMutability": "nonpayable", "type": "function" }, { "inputs": [ { "internalType": "address", "name": "_to", "type": "address" }, { "internalType": "uint256", "name": "_amount", "type": "uint256" } ], "name": "mint", "outputs": [], "stateMutability": "nonpayable", "type": "function" }, { "inputs": [ { "internalType": "uint256", "name": "amount", "type": "uint256" } ], "name": "mint", "outputs": [ { "internalType": "bool", "name": "", "type": "bool" } ], "stateMutability": "nonpayable", "type": "function" }, { "inputs": [ { "internalType": "address", "name": "delegator", "type": "address" } ], "name": "delegates", "outputs": [ { "internalType": "address", "name": "", "type": "address" } ], "stateMutability": "view", "type": "function", "constant": true }, { "inputs": [ { "internalType": "address", "name": "delegatee", "type": "address" } ], "name": "delegate", "outputs": [], "stateMutability": "nonpayable", "type": "function" }, { "inputs": [ { "internalType": "address", "name": "delegatee", "type": "address" }, { "internalType": "uint256", "name": "nonce", "type": "uint256" }, { "internalType": "uint256", "name": "expiry", "type": "uint256" }, { "internalType": "uint8", "name": "v", "type": "uint8" }, { "internalType": "bytes32", "name": "r", "type": "bytes32" }, { "internalType": "bytes32", "name": "s", "type": "bytes32" } ], "name": "delegateBySig", "outputs": [], "stateMutability": "nonpayable", "type": "function" }, { "inputs": [ { "internalType": "address", "name": "account", "type": "address" } ], "name": "getCurrentVotes", "outputs": [ { "internalType": "uint256", "name": "", "type": "uint256" } ], "stateMutability": "view", "type": "function", "constant": true }, { "inputs": [ { "internalType": "address", "name": "account", "type": "address" }, { "internalType": "uint256", "name": "blockNumber", "type": "uint256" } ], "name": "getPriorVotes", "outputs": [ { "internalType": "uint256", "name": "", "type": "uint256" } ], "stateMutability": "view", "type": "function", "constant": true }]

When I use this abi and try to verify and publish my contract on testnet, I get the following error:

Error! Invalid constructor arguments provided. Please verify that they are in ABI-encoded format

How can I get the correct format abi, so that I can verify my contract.

UPDATE: I tried to use truffle-plugin-verify to verify the smart contract on truffle and it gives me the following error. It is again pointing towards the Context.sol file but I fail to understand why because the file is visible to me in the GSN folder.

Cannot find module '@pancakeswap/pancake-swap-lib/contracts/GSN/Context.sol'
Require stack:
- C:\Users\DELL\node_modules\truffle-plugin-verify\verify.js
- C:\Users\DELL\AppData\Roaming\npm\node_modules\truffle\node_modules\original-require\index.js
- C:\Users\DELL\AppData\Roaming\npm\node_modules\truffle\build\cli.bundled.js
Failed to verify 1 contract(s): NiftToken

NiftToken.sol

//SPDX-License-Identifier: MIT
pragma solidity 0.6.12;

import "@pancakeswap/pancake-swap-lib/contracts/token/BEP20/BEP20.sol";

// NiftToken with Governance.
contract NiftToken is BEP20("NiftySwap Token", "NIFT") {
    /// @notice Creates `_amount` token to `_to`. Must only be called by the owner (MasterChef).
    function mint(address _to, uint256 _amount) public onlyOwner {
        _mint(_to, _amount);
        _moveDelegates(address(0), _delegates[_to], _amount);
    }

    // Copied and modified from YAM code:
    // https://github.com/yam-finance/yam-protocol/blob/master/contracts/token/YAMGovernanceStorage.sol
    // https://github.com/yam-finance/yam-protocol/blob/master/contracts/token/YAMGovernance.sol
    // Which is copied and modified from COMPOUND:
    // https://github.com/compound-finance/compound-protocol/blob/master/contracts/Governance/Comp.sol

    /// @notice A record of each accounts delegate
    mapping(address => address) internal _delegates;

    /// @notice A checkpoint for marking number of votes from a given block
    struct Checkpoint {
        uint32 fromBlock;
        uint256 votes;
    }

    /// @notice A record of votes checkpoints for each account, by index
    mapping(address => mapping(uint32 => Checkpoint)) public checkpoints;

    /// @notice The number of checkpoints for each account
    mapping(address => uint32) public numCheckpoints;

    /// @notice The EIP-712 typehash for the contract's domain
    bytes32 public constant DOMAIN_TYPEHASH =
        keccak256(
            "EIP712Domain(string name,uint256 chainId,address verifyingContract)"
        );

    /// @notice The EIP-712 typehash for the delegation struct used by the contract
    bytes32 public constant DELEGATION_TYPEHASH =
        keccak256("Delegation(address delegatee,uint256 nonce,uint256 expiry)");

    /// @notice A record of states for signing / validating signatures
    mapping(address => uint256) public nonces;

    /// @notice An event thats emitted when an account changes its delegate
    event DelegateChanged(
        address indexed delegator,
        address indexed fromDelegate,
        address indexed toDelegate
    );

    /// @notice An event thats emitted when a delegate account's vote balance changes
    event DelegateVotesChanged(
        address indexed delegate,
        uint256 previousBalance,
        uint256 newBalance
    );

    /**
     * @notice Delegate votes from `msg.sender` to `delegatee`
     * @param delegator The address to get delegatee for
     */
    function delegates(address delegator) external view returns (address) {
        return _delegates[delegator];
    }

    /**
     * @notice Delegate votes from `msg.sender` to `delegatee`
     * @param delegatee The address to delegate votes to
     */
    function delegate(address delegatee) external {
        return _delegate(msg.sender, delegatee);
    }

    /**
     * @notice Delegates votes from signatory to `delegatee`
     * @param delegatee The address to delegate votes to
     * @param nonce The contract state required to match the signature
     * @param expiry The time at which to expire the signature
     * @param v The recovery byte of the signature
     * @param r Half of the ECDSA signature pair
     * @param s Half of the ECDSA signature pair
     */
    function delegateBySig(
        address delegatee,
        uint256 nonce,
        uint256 expiry,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external {
        bytes32 domainSeparator =
            keccak256(
                abi.encode(
                    DOMAIN_TYPEHASH,
                    keccak256(bytes(name())),
                    getChainId(),
                    address(this)
                )
            );

        bytes32 structHash =
            keccak256(
                abi.encode(DELEGATION_TYPEHASH, delegatee, nonce, expiry)
            );

        bytes32 digest =
            keccak256(
                abi.encodePacked("\x19\x01", domainSeparator, structHash)
            );

        address signatory = ecrecover(digest, v, r, s);
        require(
            signatory != address(0),
            "NIFT::delegateBySig: invalid signature"
        );
        require(
            nonce == nonces[signatory]++,
            "NIFT::delegateBySig: invalid nonce"
        );
        require(now <= expiry, "NIFT::delegateBySig: signature expired");
        return _delegate(signatory, delegatee);
    }

    /**
     * @notice Gets the current votes balance for `account`
     * @param account The address to get votes balance
     * @return The number of current votes for `account`
     */
    function getCurrentVotes(address account) external view returns (uint256) {
        uint32 nCheckpoints = numCheckpoints[account];
        return
            nCheckpoints > 0 ? checkpoints[account][nCheckpoints - 1].votes : 0;
    }

    /**
     * @notice Determine the prior number of votes for an account as of a block number
     * @dev Block number must be a finalized block or else this function will revert to prevent misinformation.
     * @param account The address of the account to check
     * @param blockNumber The block number to get the vote balance at
     * @return The number of votes the account had as of the given block
     */
    function getPriorVotes(address account, uint256 blockNumber)
        external
        view
        returns (uint256)
    {
        require(
            blockNumber < block.number,
            "NIFT::getPriorVotes: not yet determined"
        );

        uint32 nCheckpoints = numCheckpoints[account];
        if (nCheckpoints == 0) {
            return 0;
        }

        // First check most recent balance
        if (checkpoints[account][nCheckpoints - 1].fromBlock <= blockNumber) {
            return checkpoints[account][nCheckpoints - 1].votes;
        }

        // Next check implicit zero balance
        if (checkpoints[account][0].fromBlock > blockNumber) {
            return 0;
        }

        uint32 lower = 0;
        uint32 upper = nCheckpoints - 1;
        while (upper > lower) {
            uint32 center = upper - (upper - lower) / 2; // ceil, avoiding overflow
            Checkpoint memory cp = checkpoints[account][center];
            if (cp.fromBlock == blockNumber) {
                return cp.votes;
            } else if (cp.fromBlock < blockNumber) {
                lower = center;
            } else {
                upper = center - 1;
            }
        }
        return checkpoints[account][lower].votes;
    }

    function _delegate(address delegator, address delegatee) internal {
        address currentDelegate = _delegates[delegator];
        uint256 delegatorBalance = balanceOf(delegator); // balance of underlying NIFTs (not scaled);
        _delegates[delegator] = delegatee;

        emit DelegateChanged(delegator, currentDelegate, delegatee);

        _moveDelegates(currentDelegate, delegatee, delegatorBalance);
    }

    function _moveDelegates(
        address srcRep,
        address dstRep,
        uint256 amount
    ) internal {
        if (srcRep != dstRep && amount > 0) {
            if (srcRep != address(0)) {
                // decrease old representative
                uint32 srcRepNum = numCheckpoints[srcRep];
                uint256 srcRepOld =
                    srcRepNum > 0
                        ? checkpoints[srcRep][srcRepNum - 1].votes
                        : 0;
                uint256 srcRepNew = srcRepOld.sub(amount);
                _writeCheckpoint(srcRep, srcRepNum, srcRepOld, srcRepNew);
            }

            if (dstRep != address(0)) {
                // increase new representative
                uint32 dstRepNum = numCheckpoints[dstRep];
                uint256 dstRepOld =
                    dstRepNum > 0
                        ? checkpoints[dstRep][dstRepNum - 1].votes
                        : 0;
                uint256 dstRepNew = dstRepOld.add(amount);
                _writeCheckpoint(dstRep, dstRepNum, dstRepOld, dstRepNew);
            }
        }
    }

    function _writeCheckpoint(
        address delegatee,
        uint32 nCheckpoints,
        uint256 oldVotes,
        uint256 newVotes
    ) internal {
        uint32 blockNumber =
            safe32(
                block.number,
                "NIFT::_writeCheckpoint: block number exceeds 32 bits"
            );

        if (
            nCheckpoints > 0 &&
            checkpoints[delegatee][nCheckpoints - 1].fromBlock == blockNumber
        ) {
            checkpoints[delegatee][nCheckpoints - 1].votes = newVotes;
        } else {
            checkpoints[delegatee][nCheckpoints] = Checkpoint(
                blockNumber,
                newVotes
            );
            numCheckpoints[delegatee] = nCheckpoints + 1;
        }

        emit DelegateVotesChanged(delegatee, oldVotes, newVotes);
    }

    function safe32(uint256 n, string memory errorMessage)
        internal
        pure
        returns (uint32)
    {
        require(n < 2**32, errorMessage);
        return uint32(n);
    }

    function getChainId() internal pure returns (uint256) {
        uint256 chainId;
        assembly {
            chainId := chainid()
        }
        return chainId;
    }
}

Context.sol

// SPDX-License-Identifier: GPL-3.0-or-later

pragma solidity >=0.4.0;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
contract Context {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor() internal {}

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}
8
  • When you copy the ABI from remix, make sure that you have selected the right contract from the drop-down menu (next to the ABI button). – Undead8 Apr 6 at 13:58
  • @Undead8 I did but I still get the empty array. Also, I have added more details to my question. – mahamzaidi Apr 6 at 14:01
  • I don't know about q2, but for q1, you have to select NiftToken in the dropdown menu after compiling, but before copying the ABI. Otherwise, you are just copying Context.sol ABI (empty). – Undead8 Apr 6 at 14:17
  • Yes I copy after compiling nift token. But i dont understand why context.sol automatically gets selected after i select compile. – mahamzaidi Apr 6 at 15:08
  • @mahamzaidi can you include contracts if possible? – hack3r_0m Apr 11 at 14:03
1
+50

When you hit "Compile ww1.sol", the remix will compile all contracts inside that solidity file.

After compiling the ww1.sol, If you change Context (Context.sol) to NiftToken (ww1.sol) (NOTE: don't click compile again after changing to NiftToken) and then click on compilation details then you will see the ABI of NiftToken

Example:

enter image description here

For Q2,

You don't need ABI while verifying this contract, as your contract's constructor doesn't take any arguments (which are also fetched automatically) so you can leave that blank and verify.

4
  • Can you explain why is this so? I mean why does the ide select context itself – mahamzaidi Apr 11 at 18:26
  • It's just how remix is made, no particular reason... It is an annoyance, that's all. Just remember do select the right contract before copying the abi. – Undead8 Apr 11 at 18:45
  • @mahamzaidi unfortunately, that is not mentioned in their docs, you can open an issue on their Github for clarification, I have updated answer for Q2 – hack3r_0m Apr 11 at 19:10
  • Thanks solved my problem. – mahamzaidi Apr 12 at 11:47

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