Beatland Festival

The state variable `beatToken` is declared as an address, which is valid for storing any Ethereum address, including token contract addresses. However, if the variable is intended to represent an ERC-20 token, it should reference an ERC-20 contract interface to facilitate interaction with the token’s methods.

​

```javascript

address public beatToken;

```

​

Potential Problem:

If you want to interact with an ERC-20 token, you need to use the ERC-20 token interface, which would look like:

​

```javascript

IERC20 public beatToken;

```

This allows the contract to call ERC-20 functions such as transfer(), approve(), and balanceOf().

​

Cannot call ERC-20 token methods on the beatToken.

​

The contract may not function as intended for token transfers.

Demonstrates improper typing blocks standard ERC-20 calls:

​

```javascript

function testBeatTokenBlocksERC20Call() public {

// Very minimal dummy interface

address wrong = address(festivalPass.beatToken());

​

// Expect compile-time or revert

(bool success, ) = wrong.call(

abi.encodeWithSignature("balanceOf(address)", address(this))

);

assertTrue(!success, "balanceOf should not exist on raw address");

}

```

​

This verifies the need for the IERC20 interface for direct calls. Using a raw address causes failure.

​

=> Current Contract Example:

​

The contract is using address beatToken but expects token-related functions like transfer().

​

```javascript

function transferBeatToken(address recipient, uint256 amount) public {

beatToken.transfer(recipient, amount); // Error: address does not have `transfer()` method

}

```

This will fail because an address type cannot call the transfer method, which is only available to IERC20 interfaces.

​

=> Real-World Risk

​

Functionality Breakdown: The contract will not be able to call functions like transfer(), balanceOf(), etc., on the beatToken, causing functionality to break.

​

User Experience: Users will not be able to interact with the beatToken properly, leading to failed transactions or logic issues.

​

You need to declare beatToken as an interface of the ERC-20 token, so that its methods can be invoked properly. Example fix:

​

```javascript

// In the top of contract import part you have to import following:

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

```

​

```diff

```

​