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    0.11.0 • Public • Published

    Optimism Smart Contracts (Bedrock)


    This package contains the smart contracts that compose the on-chain component of Optimism's upcoming Bedrock upgrade. We've tried to maintain 100% backwards compatibility with the existing system while also introducing new useful features. You can find detailed specifications for the contracts contained within this package here.

    Contracts Overview

    Contracts deployed to L1

    Name Proxy Type Description
    L1CrossDomainMessenger ResolvedDelegateProxy High-level interface for sending messages to and receiving messages from Optimism
    L1StandardBridge L1ChugSplashProxy Standardized system for transfering ERC20 tokens to/from Optimism
    L2OutputOracle Proxy Stores commitments to the state of Optimism which can be used by contracts on L1 to access L2 state
    OptimismPortal Proxy Low-level message passing interface
    OptimismMintableERC20Factory Proxy Deploys standard OptimismMintableERC20 tokens that are compatible with either StandardBridge
    ProxyAdmin - Contract that can upgrade L1 contracts

    Contracts deployed to L2

    Name Proxy Type Description
    GasPriceOracle Proxy Stores L2 gas price configuration values
    L1Block Proxy Stores L1 block context information (e.g., latest known L1 block hash)
    L2CrossDomainMessenger Proxy High-level interface for sending messages to and receiving messages from L1
    L2StandardBridge Proxy Standardized system for transferring ERC20 tokens to/from L1
    L2ToL1MessagePasser Proxy Low-level message passing interface
    SequencerFeeVault Proxy Vault for L2 transaction fees
    OptimismMintableERC20Factory Proxy Deploys standard OptimismMintableERC20 tokens that are compatible with either StandardBridge
    L2ProxyAdmin - Contract that can upgrade L2 contracts when sent a transaction from L1

    Legacy and deprecated contracts

    Name Location Proxy Type Description
    AddressManager L1 - Legacy upgrade mechanism (unused in Bedrock)
    DeployerWhitelist L2 Proxy Legacy contract for managing allowed deployers (unused since EVM Equivalence upgrade)
    L1BlockNumber L2 Proxy Legacy contract for accessing latest known L1 block number, replaced by L1Block


    We export contract ABIs, contract source code, and contract deployment information for this package via npm:

    npm install @eth-optimism/contracts-bedrock



    We work on this repository with a combination of Hardhat and Foundry.

    1. Install Foundry by following the instructions located here. A specific version must be used.

      foundryup -C c06b53287dc23c4e5b1b3e57c937a90114bbe166
    2. Install node modules with yarn (v1) and Node.js (16+):

      yarn install


    yarn build


    yarn test

    Running Echidna tests

    You must have Echidna installed.

    Contracts targetted for Echidna testing are located in ./contracts/echidna Each target contract is tested with a separate yarn command, for example:

    yarn echidna:aliasing



    1. Create or modify a file <network-name>.json inside of the deploy-config folder.
    2. Fill out this file according to the deployConfigSpec located inside of the `hardhat.config.ts


    1. Copy .env.example into .env
    2. Fill out the L1_RPC and PRIVATE_KEY_DEPLOYER environment variables in .env
    3. Run npx hardhat deploy --network <network-name> to deploy the L1 contracts
    4. Run npx hardhat etherscan-verify --network <network-name> --sleep to verify contracts on Etherscan


    Layout Locking

    We use a system called "layout locking" as a safety mechanism to prevent certain contract variables from being moved to different storage slots accidentally. To lock a contract variable, add it to the layout-lock.json file which has the following format:

      "MyContractName": {
        "myVariableName": {
          "slot": 1,
          "offset": 0,
          "length": 32

    With the above config, the validate-spacers hardhat task will check that we have a contract called MyContractName, that the contract has a variable named myVariableName, and that the variable is in the correct position as defined in the lock file. You should add things to the layout-lock.json file when you want those variables to never change. Layout locking should be used in combination with diffing the .storage-layout file in CI.

    Standards and Conventions



    We use Seaport-style comments with some minor modifications. Some basic rules:

    • Always use @notice since it has the same general effect as @dev but avoids confusion about when to use one over the other.
    • Include a newline between @notice and the first @param.
    • Include a newline between @param and the first @return.
    • Use a line-length of 100 characters.

    We also have the following custom tags:

    • @custom:proxied: Add to a contract whenever it's meant to live behind a proxy.
    • @custom:upgradeable: Add to a contract whenever it's meant to be used in an upgradeable contract.
    • @custom:semver: Add to a constructor to indicate the version of a contract.
    • @custom:legacy: Add to an event or function when it only exists for legacy support.


    • Use require statements when making simple assertions.
    • Use revert if throwing an error where an assertion is not being made (no custom errors). See here for an example of this in practice.
    • Error strings MUST have the format "{ContractName}: {message}" where message is a lower case string.

    Function Parameters

    • Function parameters should be prefixed with an underscore.

    Event Parameters

    • Event parameters should NOT be prefixed with an underscore.


    We use spacer variables to account for old storage slots that are no longer being used. The name of a spacer variable MUST be in the format spacer_<slot>_<offset>_<length> where <slot> is the original storage slot number, <offset> is the original offset position within the storage slot, and <length> is the original size of the variable. Spacers MUST be private.

    Proxy by Default

    All contracts should be assumed to live behind proxies (except in certain special circumstances). This means that new contracts MUST be built under the assumption of upgradeability. We use a minimal Proxy contract designed to be owned by a corresponding ProxyAdmin which follow the interfaces of OpenZeppelin's Proxy and ProxyAdmin contracts, respectively.

    Unless explicitly discussed otherwise, you MUST include the following basic upgradeability pattern for each new implementation contract:

    1. Extend OpenZeppelin's Initializable base contract.
    2. Include a uint8 public constant VERSION = X at the TOP of your contract.
    3. Include a function initialize with the modifier reinitializer(VERSION).
    4. In the constructor, set any immutable variables and call the initialize function for setting mutables.


    All (non-library and non-abstract) contracts MUST extend the Semver base contract which exposes a version() function that returns a semver-compliant version string. During the Bedrock development process the Semver value for all contracts SHOULD return 0.0.1 (this is not particularly important, but it's an easy standard to follow). When the initial Bedrock upgrade is released, the Semver value MUST be updated to 1.0.0.

    After the initial Bedrock upgrade, contracts MUST use the following versioning scheme:

    • patch releases are to be used only for changes that do NOT modify contract bytecode (such as updating comments).
    • minor releases are to be used for changes that modify bytecode OR changes that expand the contract ABI provided that these changes do NOT break the existing interface.
    • major releases are to be used for changes that break the existing contract interface OR changes that modify the security model of a contract.


    We have made an exception to the Semver rule for the WETH contract to avoid making changes to a well-known, simple, and recognizable contract.


    Tests are written using Foundry.

    All test contracts and functions should be organized and named according to the following guidelines.

    These guidelines are also encoded in a script which can be run with:

    ts-node scripts/forge-test-names.ts

    Note: This is a work in progress, not all test files are compliant with these guidelines.

    Organizing Principles

    • Solidity contracts are used to organize the test suite similar to how mocha uses describe.
    • Every non-trivial state changing function should have a separate contract for happy and sad path tests. This helps to make it very obvious where there are not yet sad path tests.
    • Simpler functions like getters and setters are grouped together into test contracts.

    Test function naming convention

    Test function names are split by underscores, into 3 or 4 parts. An example function name is test_onlyOwner_callerIsNotOwner_reverts().

    The parts are: [method]_[FunctionName]_[reason]_[success], where:

    • [method] is either test, testFuzz, or testDiff
    • [FunctionName] is the name of the function or higher level behavior being tested.
    • [reason] is an optional description for the behavior being tested.
    • [status] must be one of:
      • succeeds: used for most happy path cases
      • reverts: used for most sad path cases
      • works: used for tests which include a mix of happy and sad assertions (these should be broken up if possible)
      • fails: used for tests which 'fail' in some way other than reverting
      • benchmark: used for tests intended to establish gas costs

    Contract Naming Conventions

    Test contracts should be named one of the following according to their use:

    • TargetContract_Init for contracts that perform basic setup to be reused in other test contracts.
    • TargetContract_Function_Test for contracts containing happy path tests for a given function.
    • TargetContract_Function_TestFail for contracts containing sad path tests for a given function.




    npm i @eth-optimism/contracts-bedrock

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