feat(ctb): standardize initialization logic for L1 (#2885)

* feat(ctb): standardize initialization logic for L1

Standardizes the initialization for L1 contracts. Ensures that all
contracts use the same pattern of:
1. VERSION variable that represents the contract version.
2. constructor that sets immutables and calls initialize.
3. initialize function that sets any remaining mutables.

* op-bindings: update
Co-authored-by: Mark Tyneway <mark.tyneway@gmail.com>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

.changeset/mean-rings-attack.md

+---
+'@eth-optimism/contracts-bedrock': patch
+---
+
+Standardizes initialization logic for L1 contracts

packages/contracts-bedrock/.gas-snapshot

@@ -27,26 +27,26 @@ L1CrossDomainMessenger_Test:testCannot_L1MessengerPause() (gas: 10844)
 L1CrossDomainMessenger_Test:testCannot_L1MessengerUnpause() (gas: 10858)
 L1CrossDomainMessenger_Test:test_L1MessengerMessageVersion() (gas: 8388)
 L1CrossDomainMessenger_Test:test_L1MessengerPause() (gas: 31860)
-L1CrossDomainMessenger_Test:test_L1MessengerRelayMessageSucceeds() (gas: 61217)
-L1CrossDomainMessenger_Test:test_L1MessengerRelayMessageToSystemContract() (gas: 44837)
+L1CrossDomainMessenger_Test:test_L1MessengerRelayMessageSucceeds() (gas: 61261)
+L1CrossDomainMessenger_Test:test_L1MessengerRelayMessageToSystemContract() (gas: 44903)
 L1CrossDomainMessenger_Test:test_L1MessengerRelayShouldRevertIfPaused() (gas: 41587)
-L1CrossDomainMessenger_Test:test_L1MessengerSendMessage() (gas: 172199)
-L1CrossDomainMessenger_Test:test_L1MessengerTwiceSendMessage() (gas: 1254211)
+L1CrossDomainMessenger_Test:test_L1MessengerSendMessage() (gas: 172133)
+L1CrossDomainMessenger_Test:test_L1MessengerTwiceSendMessage() (gas: 1254167)
 L1CrossDomainMessenger_Test:test_L1MessengerUnpause() (gas: 23804)
 L1CrossDomainMessenger_Test:test_L1MessengerXDomainSenderReverts() (gas: 10599)
-L1CrossDomainMessenger_Test:test_L1MessengerxDomainMessageSenderResets() (gas: 59022)
-L1StandardBridge_Test:test_depositERC20() (gas: 452889)
-L1StandardBridge_Test:test_depositERC20To() (gas: 454644)
-L1StandardBridge_Test:test_depositETH() (gas: 247083)
-L1StandardBridge_Test:test_depositETHTo() (gas: 204967)
-L1StandardBridge_Test:test_finalizeERC20Withdrawal() (gas: 438779)
-L1StandardBridge_Test:test_finalizeETHWithdrawal() (gas: 48005)
-L1StandardBridge_Test:test_initialize() (gas: 14885)
+L1CrossDomainMessenger_Test:test_L1MessengerxDomainMessageSenderResets() (gas: 59088)
+L1StandardBridge_Test:test_depositERC20() (gas: 452890)
+L1StandardBridge_Test:test_depositERC20To() (gas: 454645)
+L1StandardBridge_Test:test_depositETH() (gas: 247039)
+L1StandardBridge_Test:test_depositETHTo() (gas: 204923)
+L1StandardBridge_Test:test_finalizeERC20Withdrawal() (gas: 438816)
+L1StandardBridge_Test:test_finalizeETHWithdrawal() (gas: 47983)
+L1StandardBridge_Test:test_initialize() (gas: 14863)
 L1StandardBridge_Test:test_onlyEOADepositERC20() (gas: 12085)
-L1StandardBridge_Test:test_onlyEOADepositETH() (gas: 30637)
-L1StandardBridge_Test:test_onlyL2BridgeFinalizeERC20Withdrawal() (gas: 23565)
-L1StandardBridge_Test:test_onlyPortalFinalizeERC20Withdrawal() (gas: 22919)
-L1StandardBridge_Test:test_receive() (gas: 391823)
+L1StandardBridge_Test:test_onlyEOADepositETH() (gas: 30615)
+L1StandardBridge_Test:test_onlyL2BridgeFinalizeERC20Withdrawal() (gas: 23543)
+L1StandardBridge_Test:test_onlyPortalFinalizeERC20Withdrawal() (gas: 22875)
+L1StandardBridge_Test:test_receive() (gas: 391801)
 L2CrossDomainMessenger_Test:testCannot_L2MessengerPause() (gas: 10843)
 L2CrossDomainMessenger_Test:test_L2MessengerMessageVersion() (gas: 8410)
 L2CrossDomainMessenger_Test:test_L2MessengerPause() (gas: 31837)
@@ -57,26 +57,26 @@ L2CrossDomainMessenger_Test:test_L2MessengerSendMessage() (gas: 119682)
 L2CrossDomainMessenger_Test:test_L2MessengerTwiceSendMessage() (gas: 133142)
 L2CrossDomainMessenger_Test:test_L2MessengerXDomainSenderReverts() (gas: 10599)
 L2CrossDomainMessenger_Test:test_L2MessengerxDomainMessageSenderResets() (gas: 54881)
-L2OutputOracleTest:testCannot_appendEmptyOutput() (gas: 24163)
-L2OutputOracleTest:testCannot_appendFutureTimetamp() (gas: 26130)
-L2OutputOracleTest:testCannot_appendOnWrongFork() (gas: 26415)
-L2OutputOracleTest:testCannot_appendOutputIfNotSequencer() (gas: 23554)
-L2OutputOracleTest:testCannot_appendUnexpectedBlockNumber() (gas: 26039)
-L2OutputOracleTest:testCannot_deleteL2Output_ifNotOwner() (gas: 24799)
-L2OutputOracleTest:testCannot_deleteL2Output_withWrongRoot() (gas: 91157)
-L2OutputOracleTest:testCannot_deleteL2Output_withWrongTime() (gas: 87150)
-L2OutputOracleTest:test_appendWithBlockhashAndHeight() (gas: 75061)
-L2OutputOracleTest:test_appendingAnotherOutput() (gas: 76861)
+L2OutputOracleTest:testCannot_appendEmptyOutput() (gas: 24119)
+L2OutputOracleTest:testCannot_appendFutureTimetamp() (gas: 26086)
+L2OutputOracleTest:testCannot_appendOnWrongFork() (gas: 26371)
+L2OutputOracleTest:testCannot_appendOutputIfNotSequencer() (gas: 23510)
+L2OutputOracleTest:testCannot_appendUnexpectedBlockNumber() (gas: 25995)
+L2OutputOracleTest:testCannot_deleteL2Output_ifNotOwner() (gas: 24777)
+L2OutputOracleTest:testCannot_deleteL2Output_withWrongRoot() (gas: 91091)
+L2OutputOracleTest:testCannot_deleteL2Output_withWrongTime() (gas: 87084)
+L2OutputOracleTest:test_appendWithBlockhashAndHeight() (gas: 75017)
+L2OutputOracleTest:test_appendingAnotherOutput() (gas: 76817)
 L2OutputOracleTest:test_changeSequencer() (gas: 55776)
-L2OutputOracleTest:test_computeL2Timestamp() (gas: 30288)
-L2OutputOracleTest:test_constructor() (gas: 48845)
-L2OutputOracleTest:test_deleteL2Output() (gas: 76604)
-L2OutputOracleTest:test_getL2Output() (gas: 83012)
-L2OutputOracleTest:test_latestBlockNumber() (gas: 76264)
-L2OutputOracleTest:test_nextBlockNumber() (gas: 15166)
-L2OutputOracleTest:test_updateOwner() (gas: 34646)
-L2OutputOracleUpgradeable_Test:test_cannotInitImpl() (gas: 8453)
-L2OutputOracleUpgradeable_Test:test_cannotInitProxy() (gas: 13430)
+L2OutputOracleTest:test_computeL2Timestamp() (gas: 30200)
+L2OutputOracleTest:test_constructor() (gas: 48823)
+L2OutputOracleTest:test_deleteL2Output() (gas: 76516)
+L2OutputOracleTest:test_getL2Output() (gas: 82924)
+L2OutputOracleTest:test_latestBlockNumber() (gas: 76220)
+L2OutputOracleTest:test_nextBlockNumber() (gas: 15144)
+L2OutputOracleTest:test_updateOwner() (gas: 34580)
+L2OutputOracleUpgradeable_Test:test_cannotInitImpl() (gas: 8476)
+L2OutputOracleUpgradeable_Test:test_cannotInitProxy() (gas: 13453)
 L2OutputOracleUpgradeable_Test:test_initValuesOnProxy() (gas: 38906)
 L2OutputOracleUpgradeable_Test:test_upgrading() (gas: 230843)
 L2StandardBridge_Test:test_ERC20BridgeFailed_whenLocalTokenIsBridge() (gas: 133097)
@@ -114,25 +114,25 @@ OptimismMintableTokenFactory_Test:test_createStandardL2Token() (gas: 1100125)
 OptimismMintableTokenFactory_Test:test_createStandardL2TokenSameTwice() (gas: 2181161)
 OptimismMintableTokenFactory_Test:test_createStandardL2TokenShouldRevertIfRemoteIsZero() (gas: 9374)
 OptimismMintableTokenFactory_Test:test_initializeShouldRevert() (gas: 12696)
-OptimismPortalUpgradeable_Test:test_cannotInitImpl() (gas: 10958)
-OptimismPortalUpgradeable_Test:test_cannotInitProxy() (gas: 15956)
-OptimismPortalUpgradeable_Test:test_initValuesOnProxy() (gas: 15967)
+OptimismPortalUpgradeable_Test:test_cannotInitImpl() (gas: 10936)
+OptimismPortalUpgradeable_Test:test_cannotInitProxy() (gas: 15934)
+OptimismPortalUpgradeable_Test:test_initValuesOnProxy() (gas: 16034)
 OptimismPortalUpgradeable_Test:test_upgrading() (gas: 230843)
-OptimismPortal_Test:test_OptimismPortalConstructor() (gas: 17286)
-OptimismPortal_Test:test_OptimismPortalContractCreationReverts() (gas: 14214)
+OptimismPortal_Test:test_OptimismPortalConstructor() (gas: 17330)
+OptimismPortal_Test:test_OptimismPortalContractCreationReverts() (gas: 14192)
 OptimismPortal_Test:test_OptimismPortalReceiveEth() (gas: 126643)
-OptimismPortal_Test:test_cannotVerifyRecentWithdrawal() (gas: 31945)
-OptimismPortal_Test:test_depositTransaction_NoValueContract() (gas: 75774)
-OptimismPortal_Test:test_depositTransaction_NoValueEOA() (gas: 76120)
-OptimismPortal_Test:test_depositTransaction_createWithZeroValueForContract() (gas: 75779)
-OptimismPortal_Test:test_depositTransaction_createWithZeroValueForEOA() (gas: 76123)
-OptimismPortal_Test:test_depositTransaction_withEthValueAndContractContractCreation() (gas: 82823)
-OptimismPortal_Test:test_depositTransaction_withEthValueAndEOAContractCreation() (gas: 74941)
-OptimismPortal_Test:test_depositTransaction_withEthValueFromContract() (gas: 82484)
-OptimismPortal_Test:test_depositTransaction_withEthValueFromEOA() (gas: 83100)
-OptimismPortal_Test:test_invalidWithdrawalProof() (gas: 45251)
-OptimismPortal_Test:test_isOutputFinalized() (gas: 132162)
-OptimismPortal_Test:test_simple_isOutputFinalized() (gas: 23965)
+OptimismPortal_Test:test_cannotVerifyRecentWithdrawal() (gas: 31901)
+OptimismPortal_Test:test_depositTransaction_NoValueContract() (gas: 75752)
+OptimismPortal_Test:test_depositTransaction_NoValueEOA() (gas: 76098)
+OptimismPortal_Test:test_depositTransaction_createWithZeroValueForContract() (gas: 75757)
+OptimismPortal_Test:test_depositTransaction_createWithZeroValueForEOA() (gas: 76101)
+OptimismPortal_Test:test_depositTransaction_withEthValueAndContractContractCreation() (gas: 82801)
+OptimismPortal_Test:test_depositTransaction_withEthValueAndEOAContractCreation() (gas: 74919)
+OptimismPortal_Test:test_depositTransaction_withEthValueFromContract() (gas: 82462)
+OptimismPortal_Test:test_depositTransaction_withEthValueFromEOA() (gas: 83078)
+OptimismPortal_Test:test_invalidWithdrawalProof() (gas: 45163)
+OptimismPortal_Test:test_isOutputFinalized() (gas: 131744)
+OptimismPortal_Test:test_simple_isOutputFinalized() (gas: 23877)
 Proxy_Test:test_clashingFunctionSignatures() (gas: 101427)
 Proxy_Test:test_implementationKey() (gas: 20942)
 Proxy_Test:test_implementationProxyCallIfNotAdmin() (gas: 30021)

packages/contracts-bedrock/.storage-layout

@@ -50,15 +50,19 @@
 ➡ L1StandardBridge
 =======================
 
-+-------------+-------------------------------------------------+------+--------+-------+----------------------------------------------------+
-| Name        | Type                                            | Slot | Offset | Bytes | Contract                                           |
-+============================================================================================================================================+
-| messenger   | contract CrossDomainMessenger                   | 0    | 0      | 20    | contracts/L1/L1StandardBridge.sol:L1StandardBridge |
-|-------------+-------------------------------------------------+------+--------+-------+----------------------------------------------------|
-| otherBridge | contract StandardBridge                         | 1    | 0      | 20    | contracts/L1/L1StandardBridge.sol:L1StandardBridge |
-|-------------+-------------------------------------------------+------+--------+-------+----------------------------------------------------|
-| deposits    | mapping(address => mapping(address => uint256)) | 2    | 0      | 32    | contracts/L1/L1StandardBridge.sol:L1StandardBridge |
-+-------------+-------------------------------------------------+------+--------+-------+----------------------------------------------------+
++---------------+-------------------------------------------------+------+--------+-------+----------------------------------------------------+
+| Name          | Type                                            | Slot | Offset | Bytes | Contract                                           |
++==============================================================================================================================================+
+| messenger     | contract CrossDomainMessenger                   | 0    | 0      | 20    | contracts/L1/L1StandardBridge.sol:L1StandardBridge |
+|---------------+-------------------------------------------------+------+--------+-------+----------------------------------------------------|
+| otherBridge   | contract StandardBridge                         | 1    | 0      | 20    | contracts/L1/L1StandardBridge.sol:L1StandardBridge |
+|---------------+-------------------------------------------------+------+--------+-------+----------------------------------------------------|
+| deposits      | mapping(address => mapping(address => uint256)) | 2    | 0      | 32    | contracts/L1/L1StandardBridge.sol:L1StandardBridge |
+|---------------+-------------------------------------------------+------+--------+-------+----------------------------------------------------|
+| _initialized  | uint8                                           | 3    | 0      | 1     | contracts/L1/L1StandardBridge.sol:L1StandardBridge |
+|---------------+-------------------------------------------------+------+--------+-------+----------------------------------------------------|
+| _initializing | bool                                            | 3    | 1      | 1     | contracts/L1/L1StandardBridge.sol:L1StandardBridge |
++---------------+-------------------------------------------------+------+--------+-------+----------------------------------------------------+
 
 =======================
 ➡ L2OutputOracle

packages/contracts-bedrock/README.md

@@ -58,3 +58,46 @@ npx hardhat deploy --network <network-name>
 In the `hardhat.config.ts`, there is a `deployConfigSpec` field that validates that the types
 are correct, be sure to export an object in the `deploy-config/<network-name>.ts` file that
 has a key for each property in the `deployConfigSpec`.
+
+## Standards and Conventions
+
+### Style
+
+#### Comments
+
+We use [Seaport](https://github.com/ProjectOpenSea/seaport/blob/main/contracts/Seaport.sol)-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:legacy`: Add to an event or function when it only exists for legacy support.
+
+#### Errors
+
+* 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](https://github.com/ethereum-optimism/optimism/blob/861ae315a6db698a8c0adb1f8eab8311fd96be4c/packages/contracts-bedrock/contracts/L2/OVM_ETH.sol#L31) 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.
+
+### 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`](./contracts/universal/Proxy.sol) contract designed to be owned by a corresponding [`ProxyAdmin`](./contracts/universal/ProxyAdmin.sol) 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)`.
+3. In the `constructor`, set any `immutable` variables and call the `initialize` function for setting mutables.

packages/contracts-bedrock/contracts/L1/L1CrossDomainMessenger.sol

@@ -13,22 +13,33 @@ import { CrossDomainMessenger } from "../universal/CrossDomainMessenger.sol";
  *         interface instead of interacting with lower-level contracts directly.
  */
 contract L1CrossDomainMessenger is CrossDomainMessenger {
+    /**
+     * @notice Contract version number.
+     */
+    uint8 public constant VERSION = 1;
+
     /**
      * @notice Address of the OptimismPortal.
      */
     OptimismPortal public portal;
 
     /**
-     * @notice Initializes the L1CrossDomainMessenger.
+     * @param _portal Address of the OptimismPortal to send and receive messages through.
+     */
+    constructor(OptimismPortal _portal) public {
+        // Mutables
+        initialize(_portal);
+    }
+
+    /**
+     * @notice Intializes mutable variables.
      *
      * @param _portal Address of the OptimismPortal to send and receive messages through.
      */
-    function initialize(OptimismPortal _portal) external {
+    function initialize(OptimismPortal _portal) public reinitializer(VERSION) {
         portal = _portal;
-
         address[] memory blockedSystemAddresses = new address[](1);
         blockedSystemAddresses[0] = address(this);
-
         _initialize(Lib_PredeployAddresses.L2_CROSS_DOMAIN_MESSENGER, blockedSystemAddresses);
     }
 

packages/contracts-bedrock/contracts/L1/L1StandardBridge.sol

 // SPDX-License-Identifier: MIT
 pragma solidity ^0.8.9;
 
+import { Initializable } from "@openzeppelin/contracts/proxy/utils/Initializable.sol";
 import { Lib_PredeployAddresses } from "../libraries/Lib_PredeployAddresses.sol";
 import { StandardBridge } from "../universal/StandardBridge.sol";
 
@@ -11,7 +12,12 @@ import { StandardBridge } from "../universal/StandardBridge.sol";
  *         L2. ERC20 tokens deposited into L2 are escrowed within this contract until withdrawal.
  *         ETH is transferred to and escrowed within the OptimismPortal contract.
  */
-contract L1StandardBridge is StandardBridge {
+contract L1StandardBridge is StandardBridge, Initializable {
+    /**
+     * @notice Contract version number.
+     */
+    uint8 public constant VERSION = 1;
+
     /**
      * @custom:legacy
      * @notice Emitted whenever a deposit of ETH from L1 into L2 is initiated.
@@ -85,11 +91,19 @@ contract L1StandardBridge is StandardBridge {
     );
 
     /**
-     * @notice Initializes the L1StandardBridge.
+     * @param _messenger Address of the L1CrossDomainMessenger.
+     */
+    constructor(address payable _messenger) public {
+        // Mutables
+        initialize(_messenger);
+    }
+
+    /**
+     * @notice Intializes mutable variables.
      *
      * @param _messenger Address of the L1CrossDomainMessenger.
      */
-    function initialize(address payable _messenger) public {
+    function initialize(address payable _messenger) public reinitializer(VERSION) {
         _initialize(_messenger, payable(Lib_PredeployAddresses.L2_STANDARD_BRIDGE));
     }
 

packages/contracts-bedrock/contracts/L1/L2OutputOracle.sol

@@ -6,6 +6,7 @@ import {
 } from "@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";
 
 /**
+ * @custom:proxied
  * @title L2OutputOracle
  * @notice The L2 state is committed to in this contract
  *         The payable keyword is used on appendL2Output to save gas on the msg.value check.
@@ -16,7 +17,7 @@ contract L2OutputOracle is OwnableUpgradeable {
     /**
      * @notice Contract version number.
      */
-    uint8 public constant L2_OUTPUT_ORACLE_VERSION = 1;
+    uint8 public constant VERSION = 1;
 
     /**
      * @notice OutputProposal represents a commitment to the L2 state.
@@ -29,6 +30,7 @@ contract L2OutputOracle is OwnableUpgradeable {
         uint256 timestamp;
     }
 
+    // TODO: Events should NOT be underscore prefixed.
     /**
      * @notice Emitted when an output is appended.
      *
@@ -101,7 +103,7 @@ contract L2OutputOracle is OwnableUpgradeable {
     /**
      * @notice A mapping from L2 block numbers to the respective output root. Note that these
      *         outputs should not be considered finalized until the finalization period (as defined
-     *        in the Optimism Portal) has passed.
+     *         in the Optimism Portal) has passed.
      */
     mapping(uint256 => OutputProposal) internal l2Outputs;
 
@@ -114,13 +116,9 @@ contract L2OutputOracle is OwnableUpgradeable {
     }
 
     /**
-     * @notice Initialize the L2OutputOracle contract.
-     *
-     * @param _submissionInterval    The desired interval in seconds at which
-     *                               checkpoints must be submitted.
+     * @param _submissionInterval    Interval in blocks at which checkpoints must be submitted.
      * @param _genesisL2Output       The initial L2 output of the L2 chain.
-     * @param _historicalTotalBlocks The number of blocks that preceding the
-     *                               initialization of the L2 chain.
+     * @param _historicalTotalBlocks Number of blocks preceding this L2 chain.
      * @param _startingBlockNumber   The number of the first L2 block.
      * @param _startingTimestamp     The timestamp of the first L2 block.
      * @param _l2BlockTime           The timestamp of the first L2 block.
@@ -141,33 +139,35 @@ contract L2OutputOracle is OwnableUpgradeable {
             _l2BlockTime < block.timestamp,
             "Output Oracle: Initial L2 block time must be less than current time"
         );
+
+        // Immutables
         SUBMISSION_INTERVAL = _submissionInterval;
         HISTORICAL_TOTAL_BLOCKS = _historicalTotalBlocks;
         STARTING_BLOCK_NUMBER = _startingBlockNumber;
         STARTING_TIMESTAMP = _startingTimestamp;
         L2_BLOCK_TIME = _l2BlockTime;
 
+        // Mutables
         initialize(_genesisL2Output, _startingBlockNumber, _sequencer, _owner);
     }
 
     /**
-     * @notice Initialize the L2OutputOracle contract.
+     * @notice Intializes mutable variables.
      *
-     * @param _genesisL2Output        The initial L2 output of the L2 chain.
+     * @param _genesisL2Output     The initial L2 output of the L2 chain.
      * @param _startingBlockNumber The timestamp to start L2 block at.
-     * @param _sequencer              The address of the sequencer.
-     * @param _owner                 The address of the owner.
+     * @param _sequencer           The address of the sequencer.
+     * @param _owner               The address of the owner.
      */
     function initialize(
         bytes32 _genesisL2Output,
         uint256 _startingBlockNumber,
         address _sequencer,
         address _owner
-    ) public reinitializer(L2_OUTPUT_ORACLE_VERSION) {
+    ) public reinitializer(VERSION) {
         l2Outputs[_startingBlockNumber] = OutputProposal(_genesisL2Output, block.timestamp);
         latestBlockNumber = _startingBlockNumber;
         __Ownable_init();
-
         changeSequencer(_sequencer);
         _transferOwnership(_owner);
     }
@@ -175,8 +175,7 @@ contract L2OutputOracle is OwnableUpgradeable {
     /**
      * @notice Accepts an L2 outputRoot and the timestamp of the corresponding L2 block. The
      *         timestamp must be equal to the current value returned by `nextTimestamp()` in order
-     *         to be accepted.
-     *         This function may only be called by the Sequencer.
+     *         to be accepted. This function may only be called by the Sequencer.
      *
      * @param _l2Output      The L2 output of the checkpoint block.
      * @param _l2BlockNumber The L2 block number that resulted in _l2Output.
@@ -226,6 +225,7 @@ contract L2OutputOracle is OwnableUpgradeable {
      *         owner, not the sequencer. Longer term, this should be replaced with a more robust
      *         mechanism which will allow deletion of proposals shown to be invalid by a fault
      *         proof.
+     *
      * @param _proposal Represents the output proposal to delete
      */
     function deleteL2Output(OutputProposal memory _proposal) external onlyOwner {

packages/contracts-bedrock/contracts/L1/OptimismPortal.sol

@@ -19,7 +19,7 @@ contract OptimismPortal is Initializable, ResourceMetering {
     /**
      * @notice Contract version number.
      */
-    uint8 public constant OPTIMISM_PORTAL_VERSION = 1;
+    uint8 public constant VERSION = 1;
 
     /**
      * @notice Emitted when a transaction is deposited from L1 to L2. The parameters of this event
@@ -94,22 +94,22 @@ contract OptimismPortal is Initializable, ResourceMetering {
     uint256[48] private __gap;
 
     /**
-     * @notice The constructor sets immutable values in the implementation.
-     *         This means that these values can only changed by an upgrade. But the efficiency gains
-     *         are worthwhile.
-     *         Also ensures that the implementation is initialized upon deployment.
+     * @param _l2Oracle                  Address of the L2OutputOracle contract.
+     * @param _finalizationPeriodSeconds Output finalization time in seconds.
      */
     constructor(L2OutputOracle _l2Oracle, uint256 _finalizationPeriodSeconds) {
-        // Set these immutable values into the bytcode of the implementation.
+        // Immutables
         L2_ORACLE = _l2Oracle;
         FINALIZATION_PERIOD_SECONDS = _finalizationPeriodSeconds;
+
+        // Mutables
         initialize();
     }
 
     /**
-     * @notice Initializes the contract and parent contract(s).
+     * @notice Intializes mutable variables.
      */
-    function initialize() public reinitializer(OPTIMISM_PORTAL_VERSION) {
+    function initialize() public reinitializer(VERSION) {
         l2Sender = DEFAULT_L2_SENDER;
         __ResourceMetering_init();
     }

packages/contracts-bedrock/contracts/test/CommonTest.t.sol

@@ -164,8 +164,7 @@ contract Messenger_Initializer is L2OutputOracle_Initializer {
         op = new OptimismPortal(oracle, 7 days);
         vm.label(address(op), "OptimismPortal");
 
-        L1Messenger = new L1CrossDomainMessenger();
-        L1Messenger.initialize(op);
+        L1Messenger = new L1CrossDomainMessenger(op);
 
         vm.etch(
             Lib_PredeployAddresses.L2_CROSS_DOMAIN_MESSENGER,
@@ -311,8 +310,7 @@ contract Bridge_Initializer is Messenger_Initializer {
 
         // Deploy the L1 bridge and initialize it with the address of the
         // L1CrossDomainMessenger
-        L1Bridge = new L1StandardBridge();
-        L1Bridge.initialize(payable(address(L1Messenger)));
+        L1Bridge = new L1StandardBridge(payable(address(L1Messenger)));
         vm.label(address(L1Bridge), "L1StandardBridge");
 
         // Deploy the L2StandardBridge, move it to the correct predeploy