Warning: Contract code size exceeds 24576 bytes

Question

I'm using hardhat and when trying to compile the code it shows me a warning containing

@uniswap/v2-periphery/contracts/UniswapV2Router02.sol:12:1: Warning: Contract code size exceeds 24576 bytes (a limit introduced in Spurious Dragon). This contract may not be deployable on mainnet. Consider enabling the optimizer (with a low "runs" value!), turning off revert strings, or using libraries.
contract UniswapV2Router02 is IUniswapV2Router02 {
^ (Relevant source part starts here and spans across multiple lines).

I'm not writing any contract with the name UniswapV2Router02 although I'm importing it in contract code

pragma solidity 0.6.6;

import '@uniswap/v2-periphery/contracts/UniswapV2Router02.sol';

How can I downsize the contract that I'm writing and import the uniswap router?

Here is the config file

const config = {
  solidity: "0.6.6",
  paths: {
    artifacts: "./src/artifects",
  },
  networks: {
    goerli: {
      chainID: 5,
      url: INFURA,
      accounts: [
        "0xTHE_ACCOUNT",
      ],
      timeout: 60000,
    },
  },
  settings: {
    optimizer: {
      enabled: true,
      runs: 200,
    },
  },
};

export default config;

Answer 1

In your hardhat project folder go to file hardhat.config.js and put the following code in the module.exports

module.exports = { solidity: { version: "0.5.15", settings: { optimizer: { enabled: true, runs: 200 } } }

hope it helps you.

Answer 2

There are some methods to reduce your contract size. firstly you should calc your contract size, then enable optimizer (with low run) to reduce smart contract size. if your problem is remains you should use this.

Answer 3

For whatever reason optimizer set in hardhat config didn't work for me as well. But I managed to deploy through remix with the same optimization parameters, could work as a temporary solution.

Answer 4

you have to add these all in hardhat.config.js file

 solidity: {
    version: "0.8.15",
    settings: {
      optimizer: {
        enabled: true,
        runs: 1,
      },
      "viaIR": true,
    }
  },
  contractSizer: {
    alphaSort: true,
    disambiguatePaths: false,
    runOnCompile: true,
    strict: true,
    only: [':ERC20$'],
  },

and then you have to install contract size to check contract size with npm.