Summary

Architecture

• The directory mandatory is renamed in core (Architecture refactoring #222)
• The directory optional is renamed in extensions (Architecture refactoring #222)
• Creation of a directory controllers which for the moment contains only the ValidationModule (Architecture refactoring #222)
• Rename contract and init function for ERC20BurnModule, ERC20MintModule, ERC20SnapshotModule to clearly indicate the inheritance from ERC20 interface (AccessControlDefaultAdminRules improvement #226)

Gas optimization

• Add a batch version for the burn, mint and transfer functions (see Fb format code #51)
• Use custom error instead of string error message (Custom error with hardhat support #217)
  See Defining Industry Standards for Custom Error Messages

Other

• Add ERC20 decimals as an argument of the initialize function (Add ERC20 decimals as an argument of the initialize function #213)
  Until now, the number of decimal was set inside the code to the value 0
  This release changes this behavior to use instead a parameter supplied by the deployer inside the function initialize.
• Add a constant VERSION to indicate the current version of the token (Add contract version #229)
• Implement an alternative to the kill function (Remove the function kill #221)
  The alternative function is the function deactivateContract inside the PauseModule, to deactivate the contract. This function set a boolean state variable isDeactivated to true and puts the contract in the pause state. The function unpause is updated to revert if the previous variable is set to true, thus the contract is in the pause state "forever".

The consequences are the following:

In standalone mode, this operation is irreversible, it is not possible to rollback.
With a proxy, it is still possible to rollback by deploying a new implementation.

Tools

• Update the Solidity version to 0.8.20, which is a requirement for the new OpenZeppelin version (5.0.0)
• Run tests with Hardhat instead of Truffle since Truffle does not support custom errors (Custom error with hardhat support #217)
• Update OpenZeppelin to the version v5.0.0-rc.0

Security

• Add new control on the DEFAULT_ADMIN_ROLE by inheriting AccessControlDefaultAdminRules (Add AccessControlDefaultAdminRules #220)
  This contract implements the following risk mitigations on top of AccessControl:

Only one account holds the DEFAULT_ADMIN_ROLE since deployment until it’s potentially renounced.

Enforces a 2-step process to transfer the DEFAULT_ADMIN_ROLE to another account.

Enforces a configurable delay between the two steps, with the ability to cancel before the transfer is accepted.

• Add a function transferadminshipDirectly (AccessControlDefaultAdminRules improvement #226)

• Remove the module OnlyDelegateCallModule since it was used to protect the function kill, which has been removed in this version ([#221](Remove the function kill #221)).

Tasks

• Add batch functions #151
  --Concerned functions: mint, burn and transfer
  --Close with the PR Batch functions #208
• Coherence name with OpenZeppelin #174
  --Close with the PR Coherence name with OZ #211
• Function kill: replace or remove #199
  --Close with the PR Remove the function kill #221
• Update OpenZeppelin to the version 5.0.0 #195
• Strengthen custom error test checks #191
  --Close with the PR Custom error with hardhat support #217
• Function to return the current version #137
  --Close with the PR Add contract version #229
• Decimal as argument #212
  --Close with the PR Add ERC20 decimals as an argument of the initialize function #213
• CVF-1 #209
  -- Close with the PR Architecture refactoring #222
• Replace AccessControl by AccessControlDefaultAdminRules #192
  --Close with the PRs Add AccessControlDefaultAdminRules #220
  && AccessControlDefaultAdminRules improvement #226
• Update release documentation

Initially planned, but reported to a next version or rejected

• Upgrade to web3 js 4.0 #201
  -- Not possible since Hardhat does not support the new web3 js version
  See hardhat with web3js v4 NomicFoundation/hardhat#4178
• Maybe replace allowance by increase&decreaseAllowance
  --No longer relevant since these two functions will be removed in the next OpenZeppelin release
  See Remove custom function allowance  #225
• Remove useless init function Remove useless init function #230
  Not sure if we should do this or not, no change for the moment