VTVL contest - ReyAdmirado's results

1. use of floating pragma

Contracts should be deployed with the same compiler version and flags that they have been tested with thoroughly. Locking the pragma helps to ensure that contracts do not accidentally get deployed using, for example, an outdated compiler version that might introduce bugs that affect the contract system negatively.

• VariableSupplyERC20Token.sol#L2

2. event is missing indexed fields

Each event should use three indexed fields if there are three or more fields

• VTVLVesting.sol#L69

3. _safemint() should be used rather than _mint() wherever possible

• FullPremintERC20Token.sol#L12

• VariableSupplyERC20Token.sol#L45

4. lines are too long

Usually lines in source code are limited to 80 characters. Today’s screens are much larger so it’s reasonable to stretch this in some cases. Since the files will most likely reside in GitHub, and GitHub starts using a scroll bar in all cases when the length is over 164 characters, the lines below should be split when they reach that length

• VTVLVesting.sol#L235
• VTVLVesting.sol#L241
• VTVLVesting.sol#L256
• VTVLVesting.sol#L260
• VTVLVesting.sol#L269
• VTVLVesting.sol#L313
• VTVLVesting.sol#L354
• VTVLVesting.sol#L357
• VTVLVesting.sol#L432

5. open todo

Code architecture, incentives, and error handling/reporting questions/issues should be resolved before deployment

• VTVLVesting.sol#L266

1. <x> += <y> costs more gas than <x> = <x> + <y> for state variables (same with -=)

• VTVLVesting.sol#L301

• VTVLVesting.sol#L381

• VTVLVesting.sol#L383

• VTVLVesting.sol#L433

• VariableSupplyERC20Token.sol#L43

2. ++i costs less gas than i++, especially when it’s used in for-loops (--i/i-- too)

Saves 6 gas per loop

• VTVLVesting.sol#L353

3. it costs more gas to initialize non-constant/non-immutable variables to zero than to let the default of zero be applied

• VTVLVesting.sol#L27
• VTVLVesting.sol#L148
• VTVLVesting.sol#L353

4. ++i/i++ should be unchecked{++i}/unchecked{i++} when it is not possible for them to overflow, as is the case when used in for-loop and while-loops

In Solidity 0.8+, there’s a default overflow check on unsigned integers. It’s possible to uncheck this in for-loops and save some gas at each iteration, but at the cost of some code readability, as this uncheck cannot be made inline.

• VTVLVesting.sol#L353

5. using > 0 costs more gas than != 0 when used on a uint in a require() statement

• FullPremintERC20Token.sol#L11

• VariableSupplyERC20Token.sol#L27

• VTVLVesting.sol#L103

• VTVLVesting.sol#L256

• VTVLVesting.sol#L257

• VTVLVesting.sol#L263

• VTVLVesting.sol#L270

• VTVLVesting.sol#L449

6. splitting require() statements that use && saves gas

• VTVLVesting.sol#L270
• VTVLVesting.sol#L344

7. use custom errors rather than revert()/require() strings to save deployment gas

https://blog.soliditylang.org/2021/04/21/custom-errors/

all the requires should use this method

8. using calldata instead of memory for read-only arguments in external functions saves gas

7 instances here:

• VTVLVesting.sol#L334-340

9. using bool for storage incurs overhead

https://github.com/OpenZeppelin/openzeppelin-contracts/blob/58f635312aa21f947cae5f8578638a85aa2519f5/contracts/security/ReentrancyGuard.sol#L23-L27 Use uint256(1) and uint256(2) for true/false to avoid a Gwarmaccess (100 gas) for the extra SLOAD, and to avoid Gsset (20000 gas) when changing from ‘false’ to ‘true’, after having been ‘true’ in the past

• AccessProtected.sol#L12

• AccessProtected.sol#L39

• VTVLVesting.sol#L45

10. usage of uint/int smaller than 32 bytes (256 bits) incurs overhead

When using elements that are smaller than 32 bytes, your contract’s gas usage may be higher. This is because the EVM operates on 32 bytes at a time. Therefore, if the element is smaller than that, the EVM must use more operations in order to reduce the size of the element from 32 bytes to the desired size. https://docs.soliditylang.org/en/v0.8.11/internals/layout_in_storage.html Use a larger size then downcast where needed

• VTVLVesting.sol#L27

• VTVLVesting.sol#L148

• VTVLVesting.sol#L176

• VTVLVesting.sol#L251

• VTVLVesting.sol#L252

• VTVLVesting.sol#L292

• VTVLVesting.sol#L323

• VTVLVesting.sol#L324

• VTVLVesting.sol#L339

• VTVLVesting.sol#L340

• VTVLVesting.sol#L371

• VTVLVesting.sol#L377

• VTVLVesting.sol#L398

• VTVLVesting.sol#L422

• VTVLVesting.sol#L429

• VTVLVesting.sol#L147

• VTVLVesting.sol#L167

• VTVLVesting.sol#L169

• VTVLVesting.sol#L170

• VTVLVesting.sol#L196

• VTVLVesting.sol#L247

• VTVLVesting.sol#L248

• VTVLVesting.sol#L249

• VTVLVesting.sol#L250

• VTVLVesting.sol#L319

• VTVLVesting.sol#L320

• VTVLVesting.sol#L321

• VTVLVesting.sol#L322

• VTVLVesting.sol#L335

• VTVLVesting.sol#L336

• VTVLVesting.sol#L337

• VTVLVesting.sol#L338