ParserError: Function, variable, struct or modifier declaration expected. Soldity ^0.8;

Question

I am facing an issue in solidity where When I declare the interface, it throws the error as shown in the title. at line 9

from solidity: ParserError: Function, variable, struct or modifier declaration expected. --> contracts/Program4.sol:9:3: | 9 | interface IL1ERC20Bridg

I checked the syntax and a few other errors of the same type on stack overflow, but to no avail.

https://ethereum.stackexchange.com/questions/90841/parsererror-function-variable-struct-or-modifier-declaration-expected I tried this one, but there is no incorrect white spaces.

https://ethereum.stackexchange.com/questions/120469/why-am-i-getting-function-variable-struct-or-modifier-declaration-expected The author had put a semicolan at the end thus prompting the error.

pragma solidity ^0.8;

import {SafeERC20} from '@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol';
import {Address} from '@openzeppelin/contracts/utils/Address.sol';
contract LendingPool 
{
  interface IL1ERC20Bridge{
    event ERC20DepositInitiated(
        address indexed _l1Token, address indexed _l2Token,
        address indexed _from, address _to, uint256 _amount, bytes _data);


    event ERC20WithdrawalFinalized(
        address indexed _l1Token, address indexed _l2Token,
        address indexed _from, address _to, uint256 _amount, bytes _data);
  }

Answer 1

You cannot declare an interface inside a contract. This type must be declared outside the smart contract and only in this way you can define an instance and call its methods or events . For this last operation you can use this statement:

[nameInterface] [nameVariable];

I adjusted your smart contract in this way:

pragma solidity ^0.8;

import {SafeERC20} from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import {Address} from "@openzeppelin/contracts/utils/Address.sol";

interface IL1ERC20Bridge {
    event ERC20DepositInitiated(
        address indexed _l1Token, address indexed _l2Token,
        address indexed _from, address _to, uint256 _amount, bytes _data);


    event ERC20WithdrawalFinalized(
        address indexed _l1Token, address indexed _l2Token,
        address indexed _from, address _to, uint256 _amount, bytes _data);
  }

contract LendingPool {
    IL1ERC20Bridge myInterface;

    // Your logic below this line...
}