v4.9.0-rc.0

• ReentrancyGuard: Add a _reentrancyGuardEntered function to expose the guard status. (#3714)
• ERC721Wrapper: add a new extension of the ERC721 token which wraps an underlying token. Deposit and withdraw guarantee that the ownership of each token is backed by a corresponding underlying token with the same identifier. (#3863)
• EnumerableMap: add a keys() function that returns an array containing all the keys. (#3920)
• Governor: add a public cancel(uint256) function. (#3983)
• Governor: Enable timestamp operation for blockchains without a stable block time. This is achieved by connecting a Governor's internal clock to match a voting token's EIP-6372 interface. (#3934)
• Strings: add equal method. (#3774)
• IERC5313: Add an interface for EIP-5313 that is now final. (#4013)
• IERC4906: Add an interface for ERC-4906 that is now Final. (#4012)
• StorageSlot: Add support for string and bytes. (#4008)
• Votes, ERC20Votes, ERC721Votes: support timestamp checkpointing using EIP-6372. (#3934)
• ERC4626: Add mitigation to the inflation attack through virtual shares and assets. (#3979)
• Strings: add toString method for signed integers. (#3773)
• ERC20Wrapper: Make the underlying variable private and add a public accessor. (#4029)
• EIP712: add EIP-5267 support for better domain discovery. (#3969)
• AccessControlDefaultAdminRules: Add an extension of AccessControl with additional security rules for the DEFAULT_ADMIN_ROLE. (#4009)
• SignatureChecker: Add isValidERC1271SignatureNow for checking a signature directly against a smart contract using ERC-1271. (#3932)
• SafeERC20: Add a forceApprove function to improve compatibility with tokens behaving like USDT. (#4067)
• ERC1967Upgrade: removed contract-wide oz-upgrades-unsafe-allow delegatecall annotation, replaced by granular annotation in UUPSUpgradeable. (#3971)
• ERC20Wrapper: self wrapping and deposit by the wrapper itself are now explicitelly forbiden. (#4100)
• ECDSA: optimize bytes32 computation by using assembly instead of abi.encodePacked. (#3853)
• ERC721URIStorage: Emit ERC-4906 MetadataUpdate in _setTokenURI. (#4012)
• ShortStrings: Added a library for handling short strings in a gas efficient way, with fallback to storage for longer strings. (#4023)
• SignatureChecker: Allow return data length greater than 32 from EIP-1271 signers. (#4038)
• UUPSUpgradeable: added granular oz-upgrades-unsafe-allow-reachable annotation to improve upgrade safety checks on latest version of the Upgrades Plugins (starting with @openzeppelin/upgrades-core@1.21.0). (#3971)
• Initializable: optimize _disableInitializers by using != instead of <. (#3787)
• Ownable2Step: make acceptOwnership public virtual to enable usecases that require overriding it. (#3960)
• UUPSUpgradeable.sol: Change visibility to the functions upgradeTo and upgradeToAndCall from external to public. (#3959)
• TimelockController: Add the CallSalt event to emit on operation schedule. (#4001)
• Reformatted codebase with latest version of Prettier Solidity. (#3898)
• Math: optimize log256 rounding check. (#3745)
• ERC20Votes: optimize by using unchecked arithmetic. (#3748)
• Multicall: annotate multicall function as upgrade safe to not raise a flag for its delegatecall. (#3961)
• ERC20Pausable, ERC721Pausable, ERC1155Pausable: Add note regarding missing public pausing functionality (#4007)
• ECDSA: Add a function toDataWithIntendedValidatorHash that encodes data with version 0x00 following EIP-191. (#4063)
• MerkleProof: optimize by using unchecked arithmetic. (#3745)

Breaking changes

• EIP712: Addition of ERC5267 support requires support for user defined value types, which was released in Solidity version 0.8.8. This requires a pragma change from ^0.8.0 to ^0.8.8.
• EIP712: Optimization of the cache for the upgradeable version affects the way name and version are set. This is no longer done through an initializer, and is instead part of the implementation's constructor. As a consequence, all proxies using the same implementation will necessarily share the same name and version. Additionally, an implementation upgrade risks changing the EIP712 domain unless the same name and version are used when deploying the new implementation contract.

Deprecations

• ERC20Permit: Added the file IERC20Permit.sol and ERC20Permit.sol and deprecated draft-IERC20Permit.sol and draft-ERC20Permit.sol since EIP-2612 is no longer a Draft. Developers are encouraged to update their imports. (#3793)
• Timers: The Timers library is now deprecated and will be removed in the next major release. (#4062)
• ERC777: The ERC777 token standard is no longer supported by OpenZeppelin. Our implementation is now deprecated and will be removed in the next major release. The corresponding standard interfaces remain available. (#4066)
• ERC1820Implementer: The ERC1820 pseudo-introspection mechanism is no longer supported by OpenZeppelin. Our implementation is now deprecated and will be removed in the next major release. The corresponding standard interfaces remain available. (#4066)

v4.8.3

Note
This release contains fixes for GHSA-mx2q-35m2-x2rh and GHSA-93hq-5wgc-jc82.

• GovernorCompatibilityBravo: Fix encoding of proposal data when signatures are missing.
• TransparentUpgradeableProxy: Fix transparency in case of selector clash with non-decodable calldata or payable mutability. (#4154)

v4.8.2

Note
This release contains a fix for GHSA-878m-3g6q-594q.

• ERC721Consecutive: Fixed a bug when _mintConsecutive is used for batches of size 1 that could lead to balance overflow. Refer to the breaking changes section in the changelog for a note on the behavior of ERC721._beforeTokenTransfer.

Breaking changes

• ERC721: The internal function _beforeTokenTransfer no longer updates balances, which it previously did when batchSize was greater than 1. This change has no consequence unless a custom ERC721 extension is explicitly invoking _beforeTokenTransfer. Balance updates in extensions must now be done explicitly using __unsafe_increaseBalance, with a name that indicates that there is an invariant that has to be manually verified.

v4.8.1

• ERC4626: Use staticcall instead of call when fetching underlying ERC-20 decimals. (#3943)

v4.8.0

Note
Don't miss the section on Breaking changes at the end.

• TimelockController: Added a new admin constructor parameter that is assigned the admin role instead of the deployer account. (#3722)
• Initializable: add internal functions _getInitializedVersion and _isInitializing (#3598)
• ERC165Checker: add supportsERC165InterfaceUnchecked for consulting individual interfaces without the full ERC165 protocol. (#3339)
• Address: optimize functionCall by calling functionCallWithValue directly. (#3468)
• Address: optimize functionCall functions by checking contract size only if there is no returned data. (#3469)
• Governor: make the relay function payable, and add support for EOA payments. (#3730)
• GovernorCompatibilityBravo: remove unused using statements. (#3506)
• ERC20: optimize _transfer, _mint and _burn by using unchecked arithmetic when possible. (#3513)
• ERC20Votes, ERC721Votes: optimize getPastVotes for looking up recent checkpoints. (#3673)
• ERC20FlashMint: add an internal _flashFee function for overriding. (#3551)
• ERC4626: use the same decimals() as the underlying asset by default (if available). (#3639)
• ERC4626: add internal _initialConvertToShares and _initialConvertToAssets functions to customize empty vaults behavior. (#3639)
• ERC721: optimize transfers by making approval clearing implicit instead of emitting an event. (#3481)
• ERC721: optimize burn by making approval clearing implicit instead of emitting an event. (#3538)
• ERC721: Fix balance accounting when a custom _beforeTokenTransfer hook results in a transfer of the token under consideration. (#3611)
• ERC721: use unchecked arithmetic for balance updates. (#3524)
• ERC721Consecutive: Implementation of EIP-2309 that allows batch minting of ERC721 tokens during construction. (#3311)
• ReentrancyGuard: Reduce code size impact of the modifier by using internal functions. (#3515)
• SafeCast: optimize downcasting of signed integers. (#3565)
• ECDSA: Remove redundant check on the v value. (#3591)
• VestingWallet: add releasable getters. (#3580)
• VestingWallet: remove unused library Math.sol. (#3605)
• VestingWallet: make constructor payable. (#3665)
• Create2: optimize address computation by using assembly instead of abi.encodePacked. (#3600)
• Clones: optimized the assembly to use only the scratch space during deployments, and optimized predictDeterministicAddress to use fewer operations. (#3640)
• Checkpoints: Use procedural generation to support multiple key/value lengths. (#3589)
• Checkpoints: Add new lookup mechanisms. (#3589)
• Arrays: Add unsafeAccess functions that allow reading and writing to an element in a storage array bypassing Solidity's "out-of-bounds" check. (#3589)
• Strings: optimize toString. (#3573)
• Ownable2Step: extension of Ownable that makes the ownership transfers a two step process. (#3620)
• Math and SignedMath: optimize function max by using > instead of >=. (#3679)
• Math: Add log2, log10 and log256. (#3670)
• Arbitrum: Update the vendored arbitrum contracts to match the nitro upgrade. (#3692)

Breaking changes

• ERC721: In order to add support for batch minting via ERC721Consecutive it was necessary to make a minor breaking change in the internal interface of ERC721. Namely, the hooks _beforeTokenTransfer and _afterTokenTransfer have one additional argument that may need to be added to overrides:

 function _beforeTokenTransfer(
     address from,
     address to,
     uint256 tokenId,
+    uint256 batchSize
 ) internal virtual override

• ERC4626: Conversion from shares to assets (and vice-versa) in an empty vault used to consider the possible mismatch between the underlying asset's and the vault's decimals. This initial conversion rate is now set to 1-to-1 irrespective of decimals, which are meant for usability purposes only. The vault now uses the assets decimals by default, so off-chain the numbers should appear the same. Developers overriding the vault decimals to a value that does not match the underlying asset may want to override the _initialConvertToShares and _initialConvertToAssets to replicate the previous behavior.

• TimelockController: During deployment, the TimelockController used to grant the TIMELOCK_ADMIN_ROLE to the deployer and to the timelock itself. The deployer was then expected to renounce this role once configuration of the timelock is over. Failing to renounce that role allows the deployer to change the timelock permissions (but not to bypass the delay for any time-locked actions). The role is no longer given to the deployer by default. A new parameter admin can be set to a non-zero address to grant the admin role during construction (to the deployer or any other address). Just like previously, this admin role should be renounced after configuration. If this param is given address(0), the role is not allocated and doesn't need to be revoked. In any case, the timelock itself continues to have this role.

Deprecations

• EIP712: Added the file EIP712.sol and deprecated draft-EIP712.sol since the EIP is no longer a Draft. Developers are encouraged to update their imports. (#3621)

-import "@openzeppelin/contracts/utils/cryptography/draft-EIP712.sol";
+import "@openzeppelin/contracts/utils/cryptography/EIP712.sol";

• ERC721Votes: Added the file ERC721Votes.sol and deprecated draft-ERC721Votes.sol since it no longer depends on a Draft EIP (EIP-712). Developers are encouraged to update their imports. (#3699)

-import "@openzeppelin/contracts/token/ERC721/extensions/draft-ERC721Votes.sol";
+import "@openzeppelin/contracts/token/ERC721/extensions/ERC721Votes.sol";

ERC-721 Compatibility Note

ERC-721 integrators that interpret contract state from events should make sure that they implement the clearing of approval that is implicit in every transfer according to the EIP. Previous versions of OpenZeppelin Contracts emitted an explicit Approval event even though it was not required by the specification, and this is no longer the case.

With the new ERC721Consecutive extension, the internal workings of ERC721 are slightly changed. Custom extensions to ERC721 should be reviewed to ensure they remain correct. The internal functions that should be considered are _ownerOf (new), _beforeTokenTransfer, and _afterTokenTransfer.

v4.7.3

⚠️ This is a patch for a medium severity issue. For more information visit the security advisory.

Breaking changes

• ECDSA: recover(bytes32,bytes) and tryRecover(bytes32,bytes) no longer accept compact signatures to prevent malleability. Compact signature support remains available using recover(bytes32,bytes32,bytes32) and tryRecover(bytes32,bytes32,bytes32).

v4.7.2

⚠️ This is a patch for three issues, including a high severity issue in GovernorVotesQuorumFraction. For more information visit the security advisories (1, 2, 3).

1. GovernorVotesQuorumFraction: Fixed quorum updates so they do not affect past proposals that failed due to lack of quorum. (#3561)
2. ERC165Checker: Added protection against large returndata. (#3587)
3. LibArbitrumL2, CrossChainEnabledArbitrumL2: Fixed detection of cross-chain calls for EOAs. Previously, calls from EOAs would be classified as cross-chain calls. (#3578)

v4.7.1

⚠️ This is a patch for a medium severity issue affecting SignatureChecker and a high severity issue affecting ERC165Checker. For more information visit the security advisories (1, 2).

• SignatureChecker: Fix an issue that causes isValidSignatureNow to revert when the target contract returns ill-encoded data. (#3552)
• ERC165Checker: Fix an issue that causes supportsInterface to revert when the target contract returns ill-encoded data. (#3552)

v4.7.0

• TimelockController: Migrate _call to _execute and allow inheritance and overriding similar to Governor. (#3317)
• CrossChainEnabledPolygonChild: replace the require statement with the custom error NotCrossChainCall. (#3380)
• ERC20FlashMint: Add customizable flash fee receiver. (#3327)
• ERC4626: add an extension of ERC20 that implements the ERC4626 Tokenized Vault Standard. (#3171)
• SafeERC20: add safePermit as mitigation against phantom permit functions. (#3280)
• Math: add a mulDiv function that can round the result either up or down. (#3171)
• Math: Add a sqrt function to compute square roots of integers, rounding either up or down. (#3242)
• Strings: add a new overloaded function toHexString that converts an address with fixed length of 20 bytes to its not checksummed ASCII string hexadecimal representation. (#3403)
• EnumerableMap: add new UintToUintMap map type. (#3338)
• EnumerableMap: add new Bytes32ToUintMap map type. (#3416)
• SafeCast: add support for many more types, using procedural code generation. (#3245)
• MerkleProof: add multiProofVerify to prove multiple values are part of a Merkle tree. (#3276)
• MerkleProof: add calldata versions of the functions to avoid copying input arrays to memory and save gas. (#3200)
• ERC721, ERC1155: simplified revert reasons. (#3254, (#3438))
• ERC721: removed redundant require statement. (#3434)
• PaymentSplitter: add releasable getters. (#3350)
• Initializable: refactored implementation of modifiers for easier understanding. (#3450)
• Proxies: remove runtime check of ERC1967 storage slots. (#3455)

Breaking changes

• Initializable: functions decorated with the modifier reinitializer(1) may no longer invoke each other.

v4.6.0

• crosschain: Add a new set of contracts for cross-chain applications. CrossChainEnabled is a base contract with instantiations for several chains and bridges, and AccessControlCrossChain is an extension of access control that allows cross-chain operation. (#3183)
• AccessControl: add a virtual _checkRole(bytes32) function that can be overridden to alter the onlyRole modifier behavior. (#3137)
• EnumerableMap: add new AddressToUintMap map type. (#3150)
• EnumerableMap: add new Bytes32ToBytes32Map map type. (#3192)
• ERC20FlashMint: support infinite allowance when paying back a flash loan. (#3226)
• ERC20Wrapper: the decimals() function now tries to fetch the value from the underlying token instance. If that calls revert, then the default value is used. (#3259)
• draft-ERC20Permit: replace immutable with constant for _PERMIT_TYPEHASH since the keccak256 of string literals is treated specially and the hash is evaluated at compile time. (#3196)
• ERC1155: Add a _afterTokenTransfer hook for improved extensibility. (#3166)
• ERC1155URIStorage: add a new extension that implements a _setURI behavior similar to ERC721's _setTokenURI. (#3210)
• DoubleEndedQueue: a new data structure that supports efficient push and pop to both front and back, useful for FIFO and LIFO queues. (#3153)
• Governor: improved security of onlyGovernance modifier when using an external executor contract (e.g. a timelock) that can operate without necessarily going through the governance protocol. (#3147)
• Governor: Add a way to parameterize votes. This can be used to implement voting systems such as fractionalized voting, ERC721 based voting, or any number of other systems. The params argument added to _countVote method, and included in the newly added _getVotes method, can be used by counting and voting modules respectively for such purposes. (#3043)
• Governor: rewording of revert reason for consistency. (#3275)
• Governor: fix an inconsistency in data locations that could lead to invalid bytecode being produced. (#3295)
• Governor: Implement IERC721Receiver and IERC1155Receiver to improve token custody by governors. (#3230)
• TimelockController: Implement IERC721Receiver and IERC1155Receiver to improve token custody by timelocks. (#3230)
• TimelockController: Add a separate canceller role for the ability to cancel. (#3165)
• Initializable: add a reinitializer modifier that enables the initialization of new modules, added to already initialized contracts through upgradeability. (#3232)
• Initializable: add an Initialized event that tracks initialized version numbers. (#3294)
• ERC2981: make royaltiInfo public to allow super call in overrides. (#3305)

Upgradeability notice

• TimelockController: (Action needed) The upgrade from <4.6 to >=4.6 introduces a new CANCELLER_ROLE that requires set up to be assignable. After the upgrade, only addresses with this role will have the ability to cancel. Proposers will no longer be able to cancel. Assigning cancellers can be done by an admin (including the timelock itself) once the role admin is set up. To do this, we recommend upgrading to the TimelockControllerWith46MigrationUpgradeable contract and then calling the migrateTo46 function.

Breaking changes

• Governor: Adds internal virtual _getVotes method that must be implemented; this is a breaking change for existing concrete extensions to Governor. To fix this on an existing voting module extension, rename getVotes to _getVotes and add a bytes memory argument. (#3043)
• Governor: Adds params parameter to internal virtual _countVote method; this is a breaking change for existing concrete extensions to Governor. To fix this on an existing counting module extension, add a bytes memory argument to _countVote. (#3043)
• Governor: Does not emit VoteCast event when params data is non-empty; instead emits VoteCastWithParams event. To fix this on an integration that consumes the VoteCast event, also fetch/monitor VoteCastWithParams events. (#3043)
• Votes: The internal virtual function _getVotingUnits was made view (which was accidentally missing). Any overrides should now be updated so they are view as well.