合约构造阶段调用UniswapV2 addLiquidityETH添加流动性失败排查

在ERC20合约的构造函数中调用UniswapV2的addLiquidityETH方法添加流动性时，交易在Router执行IUniswapV2Pair(pair).mint(to)步骤时回滚失败；但合约部署完成后，通过单独交易调用该方法则可成功执行。在Goerli测试网、以太坊主网及本地预编译Uniswap环境中测试，均返回Error: Transaction reverted without a reason string错误。

构造函数中调用_addLiquidity导致失败的代码示例 #

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@uniswap/v2-periphery/contracts/interfaces/IUniswapV2Router02.sol";
import "@uniswap/v2-core/contracts/interfaces/IUniswapV2Factory.sol";

contract SwappableLiquidityInDeploy is ERC20 {
    IUniswapV2Router02 private immutable _uniswapV2Router;
    address private immutable _uniswapV2Pair;
    
    constructor(address uniswapV2Router_) ERC20("Swappable", "SWAP") payable {
        uint256 initialBalance = 100000000 * 10 ** decimals();
    
        _mint(address(this), initialBalance);

        _uniswapV2Router = IUniswapV2Router02(uniswapV2Router_);

        _uniswapV2Pair = IUniswapV2Factory(_uniswapV2Router.factory()).createPair(
            address(this),
            _uniswapV2Router.WETH()
        );

        _addLiquidity(msg.value, initialBalance);
    }

    function _addLiquidity(uint256 ethAmount, uint256 tokenAmount) internal {
        _approve(address(this), address(_uniswapV2Router), tokenAmount);

        _uniswapV2Router.addLiquidityETH{value: ethAmount}(
            address(this),
            tokenAmount,
            0,
            0,
            address(this),
            block.timestamp
        );
    }
}

先部署再调用方法添加流动性成功的代码示例 #

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@uniswap/v2-periphery/contracts/interfaces/IUniswapV2Router02.sol";
import "@uniswap/v2-core/contracts/interfaces/IUniswapV2Factory.sol";

contract SwappableLiquidityInFunction is ERC20 {
    IUniswapV2Router02 private immutable _uniswapV2Router;
    address private immutable _uniswapV2Pair;
    
    constructor(address uniswapV2Router_) ERC20("Swappable", "SWAP") payable {
        uint256 initialBalance = 100000000 * 10 ** decimals();
    
        _mint(address(this), initialBalance);

        _uniswapV2Router = IUniswapV2Router02(uniswapV2Router_);

        _uniswapV2Pair = IUniswapV2Factory(_uniswapV2Router.factory()).createPair(
            address(this),
            _uniswapV2Router.WETH()
        );
    }

    function addLiquidityMock() public payable {
        _addLiquidity(msg.value, totalSupply());
    }

    function _addLiquidity(uint256 ethAmount, uint256 tokenAmount) internal {
        _approve(address(this), address(_uniswapV2Router), tokenAmount);

        _uniswapV2Router.addLiquidityETH{value: ethAmount}(
            address(this),
            tokenAmount,
            0,
            0,
            address(this),
            block.timestamp
        );
    }
}

内容的提问来源于stack exchange，提问作者vittominacori