ERC2891
: add implementation of the royalty standard, and the respective extensions forERC721
andERC1155
. (#3012)GovernorTimelockControl
: improve thestate()
function to have it reflect cases where a proposal has been canceled directly on the timelock. (#2977)Math
: add aabs(int256)
method that returns the unsigned absolute value of a signed value. (#2984)- Preset contracts are now deprecated in favor of Contracts Wizard. (#2986)
Governor
: add a relay function to help recover assets sent to a governor that is not its own executor (e.g. when using a timelock). (#2926)GovernorPreventLateQuorum
: add new module to ensure a minimum voting duration is available after the quorum is reached. (#2973)ERC721
: improved revert reason when transferring from wrong owner. (#2975)Votes
: Added a base contract for vote tracking with delegation. (#2944)ERC721Votes
: Added an extension of ERC721 enabled with vote tracking and delegation. (#2944)ERC2771Context
: use immutable storage to store the forwarder address, no longer an issue since Solidity >=0.8.8 allows reading immutable variables in the constructor. (#2917)Base64
: add a library to parse bytes into base64 strings usingencode(bytes memory)
function, and provide examples to show how to use to build URL-safetokenURIs
(#2884)ERC20
: reduce allowance before triggering transfer.
Initializable
: change the existinginitializer
modifier and add a newonlyInitializing
modifier to prevent reentrancy risk. (#3006)
It is no longer possible to call an initializer
-protected function from within another initializer
function outside the context of a constructor. Projects using OpenZeppelin upgradeable proxies should continue to work as is, since in the common case the initializer is invoked in the constructor directly. If this is not the case for you, the suggested change is to use the new onlyInitializing
modifier in the following way:
contract A {
- function initialize() public initializer { ... }
+ function initialize() internal onlyInitializing { ... }
}
contract B is A {
function initialize() public initializer {
A.initialize();
}
}
Ownable
: add an internal_transferOwnership(address)
. (#2568)AccessControl
: add internal_grantRole(bytes32,address)
and_revokeRole(bytes32,address)
. (#2568)AccessControl
: mark_setupRole(bytes32,address)
as deprecated in favor of_grantRole(bytes32,address)
. (#2568)AccessControlEnumerable
: hook into_grantRole(bytes32,address)
and_revokeRole(bytes32,address)
. (#2946)EIP712
: cacheaddress(this)
to immutable storage to avoid potential issues if a vanilla contract is used in a delegatecall context. (#2852)- Add internal
_setApprovalForAll
toERC721
andERC1155
. (#2834) Governor
: shift vote start and end by one block to better match Compound's GovernorBravo and prevent voting at the Governor level if the voting snapshot is not ready. (#2892)GovernorCompatibilityBravo
: consider quorum an inclusive rather than exclusive minimum to match Compound's GovernorBravo. (#2974)GovernorSettings
: a new governor module that manages voting settings updatable through governance actions. (#2904)PaymentSplitter
: now supports ERC20 assets in addition to Ether. (#2858)ECDSA
: add a variant oftoEthSignedMessageHash
for arbitrary length message hashing. (#2865)MerkleProof
: add aprocessProof
function that returns the rebuilt root hash given a leaf and a proof. (#2841)VestingWallet
: new contract that handles the vesting of Ether and ERC20 tokens following a customizable vesting schedule. (#2748)Governor
: enable receiving Ether when a Timelock contract is not used. (#2748)GovernorTimelockCompound
: fix ability to use Ether stored in the Timelock contract. (#2748)
ERC1155Supply
: HandletotalSupply
changes by hooking into_beforeTokenTransfer
to ensure consistency of balances and supply duringIERC1155Receiver.onERC1155Received
calls.
UUPSUpgradeable
: Add modifiers to preventupgradeTo
andupgradeToAndCall
being executed on any contract that is not the active ERC1967 proxy. This prevents these functions being called on implementation contracts or minimal ERC1167 clones, in particular.
TimelockController
: Add additional isOperationReady check.
ERC2771Context
: use private variable from storage to store the forwarder address. Fixes issues where_msgSender()
was not callable from constructors. (#2754)EnumerableSet
: addvalues()
functions that returns an array containing all values in a single call. (#2768)Governor
: added a modular system ofGovernor
contracts based onGovernorAlpha
andGovernorBravo
. (#2672)- Add an
interfaces
folder containing solidity interfaces to final ERCs. (#2517) ECDSA
: addtryRecover
functions that will not throw if the signature is invalid, and will return an error flag instead. (#2661)SignatureChecker
: Reduce gas usage of theisValidSignatureNow
function for the "signature by EOA" case. (#2661)
ERC20Votes
: add a new extension of theERC20
token with support for voting snapshots and delegation. (#2632)ERC20VotesComp
: Variant ofERC20Votes
that is compatible with Compound'sComp
token interface but restricts supply touint96
. (#2706)ERC20Wrapper
: add a new extension of theERC20
token which wraps an underlying token. Deposit and withdraw guarantee that the total supply is backed by a corresponding amount of underlying token. (#2633)- Enumerables: Improve gas cost of removal in
EnumerableSet
andEnumerableMap
. - Enumerables: Improve gas cost of lookup in
EnumerableSet
andEnumerableMap
. Counter
: add a reset method. (#2678)- Tokens: Wrap definitely safe subtractions in
unchecked
blocks. Math
: Add aceilDiv
method for performing ceiling division.ERC1155Supply
: add a newERC1155
extension that keeps track of the totalSupply of each tokenId. (#2593)BitMaps
: add a newBitMaps
library that provides a storage efficient datastructure foruint256
tobool
mapping with contiguous keys. (#2710)
ERC20FlashMint
is no longer a Draft ERC. (#2673))
How to update: Change your import paths by removing the draft-
prefix from @openzeppelin/contracts/token/ERC20/extensions/draft-ERC20FlashMint.sol
.
IERC20Metadata
: add a new extended interface that includes the optionalname()
,symbol()
anddecimals()
functions. (#2561)ERC777
: make reception acquirement optional in_mint
. (#2552)ERC20Permit
: add a_useNonce
to enable further usage of ERC712 signatures. (#2565)ERC20FlashMint
: add an implementation of the ERC3156 extension for flash-minting ERC20 tokens. (#2543)SignatureChecker
: add a signature verification library that supports both EOA and ERC1271 compliant contracts as signers. (#2532)Multicall
: add abstract contract withmulticall(bytes[] calldata data)
function to bundle multiple calls together (#2608)ECDSA
: add support for ERC2098 short-signatures. (#2582)AccessControl
: add aonlyRole
modifier to restrict specific function to callers bearing a specific role. (#2609)StorageSlot
: add a library for reading and writing primitive types to specific storage slots. (#2542)- UUPS Proxies: add
UUPSUpgradeable
to implement the UUPS proxy pattern together withEIP1967Proxy
. (#2542)
This release includes two small breaking changes in TimelockController
.
- The
onlyRole
modifier in this contract was designed to let anyone through if the role was granted toaddress(0)
, allowing the possibility to to make a role "open", which can be used forEXECUTOR_ROLE
. This modifier is now replaced byAccessControl.onlyRole
, which does not have this ability. The previous behavior was moved to the modifierTimelockController.onlyRoleOrOpenRole
. - It was possible to make
PROPOSER_ROLE
an open role (as described in the previous item) if it was granted toaddress(0)
. This would affect theschedule
,scheduleBatch
, andcancel
operations inTimelockController
. This ability was removed as it does not make sense to open up thePROPOSER_ROLE
in the same way that it does forEXECUTOR_ROLE
.
- Now targeting the 0.8.x line of Solidity compilers. For 0.6.x (resp 0.7.x) support, use version 3.4.0 (resp 3.4.0-solc-0.7) of OpenZeppelin.
Context
: making_msgData
returnbytes calldata
instead ofbytes memory
(#2492)ERC20
: removed the_setDecimals
function and the storage slot associated to decimals. (#2502)Strings
: addition of atoHexString
function. (#2504)EnumerableMap
: change implementation to optimize forkey → value
lookups instead of enumeration. (#2518)GSN
: deprecate GSNv1 support in favor of upcoming support for GSNv2. (#2521)ERC165
: remove uses of storage in the base ERC165 implementation. ERC165 based contracts now use storage-less virtual functions. Old behavior remains available in theERC165Storage
extension. (#2505)Initializable
: make initializer check stricter during construction. (#2531)ERC721
: remove enumerability of tokens from the base implementation. This feature is now provided separately through theERC721Enumerable
extension. (#2511)AccessControl
: removed enumerability by default for a more lightweight contract. It is now opt-in throughAccessControlEnumerable
. (#2512)- Meta Transactions: add
ERC2771Context
and aMinimalForwarder
for meta-transactions. (#2508) - Overall reorganization of the contract folder to improve clarity and discoverability. (#2503)
ERC20Capped
: optimize gas usage by enforcing the check directly in_mint
. (#2524)- Rename
UpgradeableProxy
toERC1967Proxy
. (#2547) ERC777
: optimize the gas costs of the constructor. (#2551)ERC721URIStorage
: add a new extension that implements the_setTokenURI
behavior as it was available in 3.4.0. (#2555)AccessControl
: added ERC165 interface detection. (#2562)ERC1155
: makeuri
public so overloading function can call it using super. (#2576)
AccessControlEnumerable
: FixedrenounceRole
not updating enumerable set of addresses for a role. (#2572)
Since this version has moved a few contracts to different directories, users upgrading from a previous version will need to adjust their import statements. To make this easier, the package includes a script that will migrate import statements automatically. After upgrading to the latest version of the package, run:
npx openzeppelin-contracts-migrate-imports
Make sure you're using git or another version control system to be able to recover from any potential error in our script.
Some further changes have been done between the different beta iterations. Transitions made during this period are configured in the migrate-imports
script. Consequently, you can upgrade from any previous 4.0-beta.x version using the same script as described in the How to upgrade from 3.x section.
TimelockController
: Add additional isOperationReady check.
ERC721
: made_approve
an internal function (was private).
BeaconProxy
: added new kind of proxy that allows simultaneous atomic upgrades. (#2411)EIP712
: added helpers to verify EIP712 typed data signatures on chain. (#2418)ERC20Permit
: added an implementation of the ERC20 permit extension for gasless token approvals. (#2237)- Presets: added token presets with preminted fixed supply
ERC20PresetFixedSupply
andERC777PresetFixedSupply
. (#2399) Address
: addedfunctionDelegateCall
, similar to the existingfunctionCall
. (#2333)Clones
: added a library for deploying EIP 1167 minimal proxies. (#2449)Context
: moved fromcontracts/GSN
tocontracts/utils
. (#2453)PaymentSplitter
: replace usage of.transfer()
withAddress.sendValue
for improved compatibility with smart wallets. (#2455)UpgradeableProxy
: bubble revert reasons from initialization calls. (#2454)SafeMath
: fix a memory allocation issue by adding newSafeMath.tryOp(uint,uint)→(bool,uint)
functions.SafeMath.op(uint,uint,string)→uint
are now deprecated. (#2462)EnumerableMap
: fix a memory allocation issue by adding newEnumerableMap.tryGet(uint)→(bool,address)
functions.EnumerableMap.get(uint)→string
is now deprecated. (#2462)ERC165Checker
: added batchgetSupportedInterfaces
. (#2469)RefundEscrow
:beneficiaryWithdraw
will forward all available gas to the beneficiary. (#2480)- Many view and pure functions have been made virtual to customize them via overrides. In many cases this will not imply that other functions in the contract will automatically adapt to the overridden definitions. People who wish to override should consult the source code to understand the impact and if they need to override any additional functions to achieve the desired behavior.
ERC777
: fix potential reentrancy issues for custom extensions toERC777
. (#2483)
If you're using our implementation of ERC777 from version 3.3.0 or earlier, and you define a custom _beforeTokenTransfer
function that writes to a storage variable, you may be vulnerable to a reentrancy attack. If you're affected and would like assistance please write to security@openzeppelin.com. Read more in the pull request.
- Now supports both Solidity 0.6 and 0.7. Compiling with solc 0.7 will result in warnings. Install the
solc-0.7
tag to compile without warnings. Address
: addedfunctionStaticCall
, similar to the existingfunctionCall
. (#2333)TimelockController
: added a contract to augment access control schemes with a delay. (#2354)EnumerableSet
: addedBytes32Set
, for sets ofbytes32
. (#2395)
- Resolve warnings introduced by Solidity 0.7.4. (#2396)
ERC777
: Remove a warning about function state visibility in Solidity 0.7. (#2327)
- Proxies: added the proxy contracts from OpenZeppelin SDK. (#2335)
Aside from upgrading them from Solidity 0.5 to 0.6, we've changed a few minor things from the proxy contracts as they were found in OpenZeppelin SDK.
UpgradeabilityProxy
was renamed toUpgradeableProxy
.AdminUpgradeabilityProxy
was renamed toTransparentUpgradeableProxy
.Proxy._willFallback
was renamed toProxy._beforeFallback
.UpgradeabilityProxy._setImplementation
andAdminUpgradeabilityProxy._setAdmin
were made private.
Address.isContract
: switched fromextcodehash
toextcodesize
for less gas usage. (#2311)
ERC20Snapshot
: switched to using_beforeTokenTransfer
hook instead of overriding ERC20 operations. (#2312)
This small change in the way we implemented ERC20Snapshot
may affect users who are combining this contract with
other ERC20 flavors, since it no longer overrides _transfer
, _mint
, and _burn
. This can result in having to remove Solidity override(...)
specifiers in derived contracts for these functions, and to instead have to add it for _beforeTokenTransfer
. See Using Hooks in the documentation.
SafeCast
: added functions to downcast signed integers (e.g.toInt32
), improving usability ofSignedSafeMath
. (#2243)functionCall
: new helpers that replicate Solidity's function call semantics, reducing the need to rely oncall
. (#2264)ERC1155
: added support for a base implementation, non-standard extensions and a preset contract. (#2014, #2230)
ReentrancyGuard
: reduced overhead of using thenonReentrant
modifier. (#2171)AccessControl
: added aRoleAdminChanged
event to_setAdminRole
. (#2214)- Made all
public
functions in the token preset contractsvirtual
. (#2257)
SafeERC20
: deprecatedsafeApprove
. (#2268)
- Added SPX license identifier to all contracts. (#2235)
ERC777
: fixed the_approve
internal function not validating some of their arguments for non-zero addresses. (#2213)
AccessControl
: new contract for managing permissions in a system, replacement forOwnable
andRoles
. (#2112)SafeCast
: new functions to convert to and from signed and unsigned values:toUint256
andtoInt256
. (#2123)EnumerableMap
: a new data structure for key-value pairs (likemapping
) that can be iterated over. (#2160)
ERC721
:burn(owner, tokenId)
was removed, useburn(tokenId)
instead. (#2125)ERC721
:_checkOnERC721Received
was removed. (#2125)ERC721
:_transferFrom
and_safeTransferFrom
were renamed to_transfer
and_safeTransfer
. (#2162)Ownable
: removed_transferOwnership
. (#2162)PullPayment
,Escrow
:withdrawWithGas
was removed. The oldwithdraw
function now forwards all gas. (#2125)Roles
was removed, useAccessControl
as a replacement. (#2112)ECDSA
: when receiving an invalid signature,recover
now reverts instead of returning the zero address. (#2114)Create2
: added anamount
argument todeploy
for contracts withpayable
constructors. (#2117)Pausable
: moved to theutils
directory. (#2122)Strings
: moved to theutils
directory. (#2122)Counters
: moved to theutils
directory. (#2122)SignedSafeMath
: moved to themath
directory. (#2122)ERC20Snapshot
: moved to thetoken/ERC20
directory.snapshot
was changed into aninternal
function. (#2122)Ownable
: moved to theaccess
directory. (#2120)Ownable
: removedisOwner
. (#2120)Secondary
: removed from the library, useOwnable
instead. (#2120)Escrow
,ConditionalEscrow
,RefundEscrow
: these now useOwnable
instead ofSecondary
, their external API changed accordingly. (#2120)ERC20
: removed_burnFrom
. (#2119)Address
: removedtoPayable
, usepayable(address)
instead. (#2133)ERC777
:_send
,_mint
and_burn
now use the caller as the operator. (#2134)ERC777
: removed_callsTokensToSend
and_callTokensReceived
. (#2134)EnumerableSet
: renamedget
toat
. (#2151)ERC165Checker
: functions no longer have a leading underscore. (#2150)ERC721Metadata
,ERC721Enumerable
: these contracts were removed, and their functionality merged intoERC721
. (#2160)ERC721
: added a constructor forname
andsymbol
. (#2160)ERC20Detailed
: this contract was removed and its functionality merged intoERC20
. (#2161)ERC20
: added a constructor forname
andsymbol
.decimals
now defaults to 18. (#2161)Strings
: renamedfromUint256
totoString
(#2188)
ERC777
: fixed the_send
and_approve
internal functions not validating some of their arguments for non-zero addresses. (#2212)
SafeCast.toUintXX
: new library for integer downcasting, which allows for safe operation on smaller types (e.g.uint32
) when combined withSafeMath
. (#1926)ERC721Metadata
: addedbaseURI
, which can be used for dramatic gas savings when all token URIs share a prefix (e.g.http://api.myapp.com/tokens/<id>
). (#1970)EnumerableSet
: new library for storing enumerable sets of values. OnlyAddressSet
is supported in this release. (#2061)Create2
: simple library to make usage of theCREATE2
opcode easier. (#1744)
ERC777
:_burn
is now internal, providing more flexibility and making it easier to create tokens that deflate. (#1908)ReentrancyGuard
: greatly improved gas efficiency by using the net gas metering mechanism introduced in the Istanbul hardfork. (#1992, #1996)ERC777
: improve extensibility by making_send
and related functionsinternal
. (#2027)ERC721
: improved revert reason when transferring tokens to a non-recipient contract. (#2018)
ERC165Checker
now requires a minimum Solidity compiler version of 0.5.10. (#1829)
Address.toPayable
: added a helper to convert between address types without having to resort to low-level casting. (#1773)- Facilities to make metatransaction-enabled contracts through the Gas Station Network. (#1844)
Address.sendValue
: added a replacement to Solidity'stransfer
, removing the fixed gas stipend. (#1962)- Added replacement for functions that don't forward all gas (which have been deprecated): (#1976)
PullPayment.withdrawPaymentsWithGas(address payable payee)
Escrow.withdrawWithGas(address payable payee)
SafeMath
: added support for custom error messages tosub
,div
andmod
functions. (#1828)
Address.isContract
: switched fromextcodesize
toextcodehash
for less gas usage. (#1802)ERC20
andERC777
updated to throw custom errors on subtraction overflows. (#1828)
- Deprecated functions that don't forward all gas: (#1976)
PullPayment.withdrawPayments(address payable payee)
Escrow.withdraw(address payable payee)
Address
now requires a minimum Solidity compiler version of 0.5.5. (#1802)SignatureBouncer
has been removed from drafts, both to avoid confusions with the GSN andGSNRecipientSignature
(previously calledGSNBouncerSignature
) and because the API was not very clear. (#1879)
The final 2.4.0 release includes a refactor of the GSN contracts that will be a breaking change for 2.4.0-beta users.
- The default empty implementations of
_preRelayedCall
and_postRelayedCall
were removed and must now be explicitly implemented always in custom recipients. If your custom recipient didn't include an implementation, you can provide an empty one. GSNRecipient
,GSNBouncerBase
, andGSNContext
were all merged intoGSNRecipient
.GSNBouncerSignature
andGSNBouncerERC20Fee
were renamed toGSNRecipientSignature
andGSNRecipientERC20Fee
.- It is no longer necessary to inherit from
GSNRecipient
when usingGSNRecipientSignature
andGSNRecipientERC20Fee
.
For example, a contract using GSNBouncerSignature
would have to be changed in the following way.
-contract MyDapp is GSNRecipient, GSNBouncerSignature {
+contract MyDapp is GSNRecipientSignature {
Refer to the table below to adjust your inheritance list.
2.4.0-beta | 2.4.0 |
---|---|
GSNRecipient, GSNBouncerSignature |
GSNRecipientSignature |
GSNRecipient, GSNBouncerERC20Fee |
GSNRecipientERC20Fee |
GSNBouncerBase |
GSNRecipient |
ERC1820
: added support for interacting with the ERC1820 registry contract (IERC1820Registry
), as well as base contracts that can be registered as implementers there. (#1677)ERC777
: support for the ERC777 token, which has multiple improvements overERC20
(but is backwards compatible with it) such as built-in burning, a more straightforward permission system, and optional sender and receiver hooks on transfer (mandatory for contracts!). (#1684)- All contracts now have revert reason strings, which give insight into error conditions, and help debug failing transactions. (#1704)
- Reverted the Solidity version bump done in v2.2.0, setting the minimum compiler version to v0.5.0, to prevent unexpected build breakage. Users are encouraged however to stay on top of new compiler releases, which usually include bugfixes. (#1729)
PostDeliveryCrowdsale
: some validations where skipped when paired with other crowdsale flavors, such asAllowanceCrowdsale
, orMintableCrowdsale
andERC20Capped
, which could cause buyers to not be able to claim their purchased tokens. (#1721)ERC20._transfer
: thefrom
argument was allowed to be the zero address, so it was possible to internally trigger a transfer of 0 tokens from the zero address. This address is not a valid destinatary of transfers, nor can it give or receive allowance, so this behavior was inconsistent. It now reverts. (#1752)
ERC20Snapshot
: create snapshots on demand of the token balances and total supply, to later retrieve and e.g. calculate dividends at a past time. (#1617)SafeERC20
:ERC20
contracts with no return value (i.e. that revert on failure) are now supported. (#1655)ERC20
: added internal_approve(address owner, address spender, uint256 value)
, allowing derived contracts to set the allowance of arbitrary accounts. (#1609)ERC20Metadata
: added internal_setTokenURI(string memory tokenURI)
. (#1618)TimedCrowdsale
: added internal_extendTime(uint256 newClosingTime)
as well asTimedCrowdsaleExtended(uint256 prevClosingTime, uint256 newClosingTime)
event allowing to extend the crowdsale, as long as it hasn't already closed.
- Upgraded the minimum compiler version to v0.5.2: this removes many Solidity warnings that were false positives. (#1606)
ECDSA
:recover
no longer accepts malleable signatures (those using upper-range values fors
, or 0/1 forv
). (#1622)ERC721
's transfers are now more gas efficient due to removal of unnecessarySafeMath
calls. (#1610)- Fixed variable shadowing issues. (#1606)
- (minor)
SafeERC20
:safeApprove
wasn't properly checking for a zero allowance when attempting to set a non-zero allowance. (#1647)
TokenMetadata
has been renamed toERC20Metadata
. (#1618)- The library
Counter
has been renamed toCounters
and its API has been improved. See an example inERC721
, lines 17 and 204. (#1610)
- Backported
SafeERC20.safeApprove
bugfix. (#1647)
- Removed most of the test suite from the npm package, except
PublicRole.behavior.js
, which may be useful to users testing their ownRoles
.
- Version bump to avoid conflict in the npm registry.
- Now targeting the 0.5.x line of Solidity compilers. For 0.4.24 support, use version 2.0 of OpenZeppelin.
WhitelistCrowdsale
: a crowdsale where only whitelisted accounts (WhitelistedRole
) can purchase tokens. Adding or removing accounts from the whitelist is done by whitelist admins (WhitelistAdminRole
). Similar to the pre-2.0WhitelistedCrowdsale
. (#1525, #1589)RefundablePostDeliveryCrowdsale
: replacement forRefundableCrowdsale
(deprecated, see below) where tokens are only granted once the crowdsale ends (if it meets its goal). (#1543)PausableCrowdsale
: allows for pausers (PauserRole
) to pause token purchases. Other crowdsale operations (e.g. withdrawals and refunds, if applicable) are not affected. (#832)ERC20
:transferFrom
and_burnFrom
now emitApproval
events, to represent the token's state comprehensively through events. (#1524)ERC721
: added_burn(uint256 tokenId)
, replacing the similar deprecated function (see below). (#1550)ERC721
: added_tokensOfOwner(address owner)
, allowing to internally retrieve the array of an account's owned tokens. (#1522)- Crowdsales: all constructors are now
public
, meaning it is not necessary to extend these contracts in order to deploy them. The exception isFinalizableCrowdsale
, since it is meaningless unless extended. (#1564) SignedSafeMath
: added overflow-safe operations for signed integers (int256
). (#1559, #1588)
- The compiler version required by
Array
was behind the rest of the libray so it was updated tov0.4.24
. (#1553) - Now conforming to a 4-space indentation code style. (1508)
ERC20
: more gas efficient due to removed redundantrequire
s. (#1409)ERC721
: fixed a bug that prevented internal data structures from being properly cleaned, missing potential gas refunds. (#1539 and #1549)ERC721
: general gas savings ontransferFrom
,_mint
and_burn
, due to redudantrequire
s andSSTORE
s. (#1549)