Identifier already declared

Smart Contracts
1 
// SPDX-License-Identifier: MIT
pragma solidity 0.8.19;

import "@openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "./IWhitelist.sol";

{
  errors: [
    {
      component: 'general',
      errorCode: '2333',
      formattedMessage: 'DeclarationError: Identifier already declared.\n' +
        '  --> IERC721Enumerable.sol:14:1:\n' +
        '   |\n' +
        '14 | abstract contract ERC721Enumerable is ERC721, IERC721Enumerable {\n' +
        '   | ^ (Relevant source part starts here and spans across multiple lines).\n' +
        'Note: The previous declaration is here:\n' +
        ' --> IERC721Enumerable.sol:6:1:\n' +
        '  |\n' +
        '6 | import "../ERC721.sol";\n' +
        '  | ^^^^^^^^^^^^^^^^^^^^^^^\n' +
        '\n',
      message: 'Identifier already declared.',
      secondarySourceLocations: [Array],
      severity: 'error',
      sourceLocation: [Object],
      type: 'DeclarationError'
    }
  ],
  sources: {
    '@openzeppelin/ERC721.sol': { id: 0 },
    '@openzeppelin/IERC721Enumerable.sol': { id: 1 },
    '@openzeppelin/contracts/ERC721.sol': { id: 2 },
    '@openzeppelin/contracts/IERC721Enumerable.sol': { id: 3 },
    '@openzeppelin/contracts/access/IERC721Enumerable.sol': { id: 4 },
    '@openzeppelin/contracts/access/Ownable.sol': { id: 5 },
    '@openzeppelin/contracts/token/ERC721.sol': { id: 6 },
    '@openzeppelin/contracts/token/ERC721/ERC721.sol': { id: 7 },
    '@openzeppelin/contracts/token/ERC721/IERC721Enumerable.sol': { id: 8 },
    '@openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol': { id: 9 },
    '@openzeppelin/contracts/token/ERC721/extensions/IERC721Enumerable.sol': { id: 10 },
    '@openzeppelin/contracts/token/IERC721Enumerable.sol': { id: 11 },
    'CryptoDevs.sol': { id: 12 },
    'ERC721.sol': { id: 13 },
    'IERC721Enumerable.sol': { id: 14 },
    'IWhitelist.sol': { id: 15 }
  }
}

Hi, yes I can see that the forum has similar topics but I don't really get it... so everytime I install openzeppelin contracts I should go and edit most of it just to use multiple ones?....

2

Please share ALL the relevant code (no, the above is insufficient for reproducing the problem).

3

CryptoDevs.sol

// SPDX-License-Identifier: MIT
pragma solidity 0.8.19;

import "@openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "./IWhitelist.sol";

contract CryptoDevs is ERC721, Ownable {
    string _baseTokenURI;

    uint256 public _price = 0.01 ether;

    bool public _paused;
    uint8 public tokenIds;
    uint8 _maxTokenIds = 10;

    IWhitelist whitelist;

    bool public presaleStarted;
    uint256 public presaleEnded;

    modifier onlyWhenNotPaused{
        require(!_paused, "The presale is paused rn");
        _;
    }

    constructor (string memory baseURI, address whitelistContract) ERC721('CryptoDevs', "CD"){
        _baseTokenURI = baseURI;
        whitelist = IWhitelist(whitelistContract);
    }

    function startPresale() public onlyOwner {
        presaleStarted = true;
        presaleEnded = block.timestamp + 5 minutes;
    }

    function presaleMint() public payable onlyWhenNotPaused{
        require(presaleStarted && block.timestamp < presaleEnded, "Presale is not active rn");
        require(whitelist.whitelistedAddresses(msg.sender), "You are not whitelisted");
        require(msg.value >= _price, "Wrong amount of ether sent");
        require(tokenIds < _maxTokenIds, "No NFTs left to mint");
        tokenIds += 1;

        _safeMint(msg.sender, tokenIds);
    }

    function mint() public payable onlyWhenNotPaused {
        require(presaleStarted && block.timestamp >=  presaleEnded, "Presale has not ended yet");
        require(tokenIds < _maxTokenIds, "Exceed maximum Crypto Devs supply");
        require(msg.value >= _price, "Ether sent is not correct");
        tokenIds += 1;
        _safeMint(msg.sender, tokenIds);
    }

    function _baseURI() internal view virtual override returns(string memory) {
        return _baseTokenURI;
    }

    function setPaused(bool val) public onlyOwner{
        _paused = val;
    }

    function withdraw() public onlyOwner  {
        address _owner = owner();
        uint256 amount = address(this).balance;
        (bool sent, ) =  _owner.call{value: amount}("");
        require(sent, "Failed to send Ether");
    }

    receive() external payable {}

    fallback() external payable {}
}

index.ts

import fs from 'fs';
//@ts-ignore
import solc from 'solc';
import { JsonRpcProvider, ContractFactory, Wallet } from 'ethers';
import 'dotenv/config';
import { METADATA_URL, WHITELIST_CONTRACT_ADDRESS } from './config';

(async () => {
	const source = fs.readFileSync('./contracts/CryptoDevs.sol', 'utf-8');

	const findImports = () => {
		const lines = source.split('\n');
		for (let line of lines) {
			if (/import "/i.test(line)) {
				const neededPart = line.split('"')[1];

				if (/@/.test(neededPart)) {
					return {
						contents: fs.readFileSync('./node_modules/' + neededPart, 'utf-8'),
					};
				} else {
					return {
						contents: fs.readFileSync('./contracts' + neededPart.slice(1)),
					};
				}
			}
		}
	};

	const input = {
		language: 'Solidity',
		sources: {
			'CryptoDevs.sol': {
				content: source,
			},
		},
		settings: {
			outputSelection: {
				'*': {
					'*': ['*'],
				},
			},
		},
	};

	const contractsData = JSON.parse(solc.compile(JSON.stringify(input), { import: findImports }));
	console.log(contractsData);
})();

Thank you

4

index.ts is in the root folder and
CryptoDevs.sol and IWhitelist.sol are in the ./contracts folder

IWhitelist.sol

// SPDX-License-Identifier: MIT
pragma solidity 0.8.19;

interface IWhitelist {
    function whitelistedAddresses(address) external view returns (bool);
}
7

IERC721Enumerable is present twice:

  • once as @openzeppelin/contracts/IERC721Enumerable.sol
  • once as IERC721Enumerable.sol

You probably should not have that second file in your codebase

8

yes thank you. But I don't have any files not outside the @openzeppelin folder, I just installed it with npm and imported 2 files

import "@openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

but I found a workaround I just compile it with the Juan Blanco extension just by pressing f5 so I don't need any code to compile the contract and it works fine.. still it would be good to understand why such stuff happens but at least I can compile the contract....which is almost all I wanted)