add OptimismMintableFiatTokenV2_2

@types/AnyFiatTokenV2Instance.d.ts

@@ -19,7 +19,7 @@
 import { FiatTokenV2Instance } from "./generated/FiatTokenV2";
 import { FiatTokenV2_1Instance } from "./generated/FiatTokenV2_1";
 import { FiatTokenV2_2Instance } from "./generated/FiatTokenV2_2";
-import { OptimismFiatTokenV2_2Instance } from "./generated/OptimismFiatTokenV2_2";
+import { OptimismMintableFiatTokenV2_2Instance } from "./generated/OptimismMintableFiatTokenV2_2";
 
 export interface FiatTokenV2_2InstanceExtended extends FiatTokenV2_2Instance {
   permit?: typeof FiatTokenV2Instance.permit;
@@ -28,8 +28,8 @@ export interface FiatTokenV2_2InstanceExtended extends FiatTokenV2_2Instance {
   cancelAuthorization?: typeof FiatTokenV2Instance.cancelAuthorization;
 }
 
-export interface OptimismFiatTokenV2_2InstanceExtended
-  extends OptimismFiatTokenV2_2Instance {
+export interface OptimismMintableFiatTokenV2_2InstanceExtended
+  extends OptimismMintableFiatTokenV2_2Instance {
   permit?: typeof FiatTokenV2Instance.permit;
   transferWithAuthorization?: typeof FiatTokenV2Instance.transferWithAuthorization;
   receiveWithAuthorization?: typeof FiatTokenV2Instance.receiveWithAuthorization;
@@ -40,4 +40,4 @@ export type AnyFiatTokenV2Instance =
   | FiatTokenV2Instance
   | FiatTokenV2_1Instance
   | FiatTokenV2_2InstanceExtended
-  | OptimismFiatTokenV2_2InstanceExtended;
+  | OptimismMintableFiatTokenV2_2InstanceExtended;

contracts/v2/IOptimismMintableERC20.sol → contracts/v2/IOptimismMintableFiatToken.sol

@@ -19,3 +19,20 @@ interface IOptimismMintableERC20 is IERC165 {
 
     function burn(address _from, uint256 _amount) external;
 }
+
+/**
+ * @title IOptimismMintableFiatToken
+ * @author Lattice (https://lattice.xyz)
+ * @notice This interface adds the functions from IOptimismMintableERC20 missing from FiatTokenV2_2.
+ *         It doesn't include `mint(address _to, uint256 _amount)`, as this function already exists
+ *         on FiatTokenV2_2 (from FiatTokenV1), and can't be overridden. The only difference is a
+ *         (bool) return type for the FiatTokenV1 version, which doesn't matter for consumers of
+ *         IOptimismMintableERC20 that don't expect a return type.
+ */
+interface IOptimismMintableFiatToken is IERC165 {
+    function remoteToken() external view returns (address);
+
+    function bridge() external returns (address);
+
+    function burn(address _from, uint256 _amount) external;
+}

contracts/v2/OptimismMintableFiatTokenV2_2.sol

@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: MIT
+pragma solidity 0.6.12;
+
+import { FiatTokenV1 } from "../v1/FiatTokenV1.sol";
+import { FiatTokenV2_2 } from "./FiatTokenV2_2.sol";
+import {
+    IOptimismMintableERC20,
+    IOptimismMintableFiatToken
+} from "./IOptimismMintableFiatToken.sol";
+import { IERC165 } from "@openzeppelin/contracts/introspection/IERC165.sol";
+
+/**
+ * @title OptimismMintableFiatTokenV2_2
+ * @author Lattice (https://lattice.xyz)
+ * @notice Adds compatibility with IOptimismMintableERC20 to the Bridged USDC Standard,
+ *         so it can be used with Optimism's StandardBridge.
+ */
+contract OptimismMintableFiatTokenV2_2 is
+    FiatTokenV2_2,
+    IOptimismMintableFiatToken
+{
+    address private immutable l1RemoteToken;
+
+    constructor(address _l1RemoteToken) public FiatTokenV2_2() {
+        l1RemoteToken = _l1RemoteToken;
+    }
+
+    function remoteToken() external override view returns (address) {
+        return l1RemoteToken;
+    }
+
+    function bridge() external override returns (address) {
+        // OP Stack L2StandardBridge predeploy
+        // https://specs.optimism.io/protocol/predeploys.html
+        return address(0x4200000000000000000000000000000000000010);
+    }
+
+    function supportsInterface(bytes4 interfaceId)
+        external
+        override
+        view
+        returns (bool)
+    {
+        return
+            interfaceId == type(IOptimismMintableERC20).interfaceId ||
+            interfaceId == type(IERC165).interfaceId;
+    }
+
+    /**
+     * @notice Allows a minter to burn tokens for the given account.
+     * @dev The caller must be a minter, must not be blacklisted, and the amount to burn
+     *      should be less than or equal to the account's balance.
+     *      The function is a requirement for IOptimismMintableERC20.
+     *      It is mostly equivalent to FiatTokenV1.burn, with the only change being
+     *      the additional _from parameter to burn from instead of burning from msg.sender.
+     * @param _amount the amount of tokens to be burned.
+     */
+    function burn(address _from, uint256 _amount)
+        external
+        override
+        whenNotPaused
+        onlyMinters
+        notBlacklisted(msg.sender)
+    {
+        uint256 balance = _balanceOf(_from);
+        require(_amount > 0, "FiatToken: burn amount not greater than 0");
+        require(balance >= _amount, "FiatToken: burn amount exceeds balance");
+
+        totalSupply_ = totalSupply_.sub(_amount);
+        _setBalance(_from, balance.sub(_amount));
+        emit Burn(_from, _amount);
+        emit Transfer(_from, address(0), _amount);
+    }
+}

scripts/deploy/DeployImpl.sol

@@ -20,8 +20,8 @@ pragma solidity 0.6.12;
 
 import { FiatTokenV2_2 } from "../../contracts/v2/FiatTokenV2_2.sol";
 import {
-    OptimismFiatTokenV2_2
-} from "../../contracts/v2/OptimismFiatTokenV2_2.sol";
+    OptimismMintableFiatTokenV2_2
+} from "../../contracts/v2/OptimismMintableFiatTokenV2_2.sol";
 
 /**
  * @notice A utility contract that exposes a re-useable getOrDeployImpl function.
@@ -74,16 +74,16 @@ contract DeployImpl {
      *
      * @param impl configured of the implementation contract, where address(0) represents a new instance should be deployed
      * @param l1RemoteToken token on the L1 corresponding to this bridged version of the token
-     * @return OptimismFiatTokenV2_2 newly deployed or loaded instance
+     * @return OptimismMintableFiatTokenV2_2 newly deployed or loaded instance
      */
     function getOrDeployImpl(address impl, address l1RemoteToken)
         internal
         returns (FiatTokenV2_2)
     {
-        OptimismFiatTokenV2_2 fiatTokenV2_2;
+        OptimismMintableFiatTokenV2_2 fiatTokenV2_2;
 
         if (impl == address(0)) {
-            fiatTokenV2_2 = new OptimismFiatTokenV2_2(l1RemoteToken);
+            fiatTokenV2_2 = new OptimismMintableFiatTokenV2_2(l1RemoteToken);
 
             // Initializing the implementation contract with dummy values here prevents
             // the contract from being reinitialized later on with different values.
@@ -106,7 +106,7 @@ contract DeployImpl {
                 newSymbol: ""
             });
         } else {
-            fiatTokenV2_2 = OptimismFiatTokenV2_2(impl);
+            fiatTokenV2_2 = OptimismMintableFiatTokenV2_2(impl);
         }
 
         return fiatTokenV2_2;

scripts/deploy/deploy-fiat-token.s.sol

@@ -24,8 +24,8 @@ import { DeployImpl } from "./DeployImpl.sol";
 import { FiatTokenProxy } from "../../contracts/v1/FiatTokenProxy.sol";
 import { FiatTokenV2_2 } from "../../contracts/v2/FiatTokenV2_2.sol";
 import {
-    OptimismFiatTokenV2_2
-} from "../../contracts/v2/OptimismFiatTokenV2_2.sol";
+    OptimismMintableFiatTokenV2_2
+} from "../../contracts/v2/OptimismMintableFiatTokenV2_2.sol";
 import { MasterMinter } from "../../contracts/minting/MasterMinter.sol";
 
 /**

scripts/deploy/set-l2-standard-bridge.s.sol

@@ -4,8 +4,8 @@ pragma solidity 0.6.12;
 import "forge-std/console.sol"; // solhint-disable no-global-import, no-console
 import { Script } from "forge-std/Script.sol";
 import {
-    OptimismFiatTokenV2_2
-} from "../../contracts/v2/OptimismFiatTokenV2_2.sol";
+    OptimismMintableFiatTokenV2_2
+} from "../../contracts/v2/OptimismMintableFiatTokenV2_2.sol";
 import { MasterMinter } from "../../contracts/minting/MasterMinter.sol";
 
 /**
@@ -17,14 +17,14 @@ contract SetL2StandardBridge is Script {
      */
     function run(
         address masterMinterOwner,
-        OptimismFiatTokenV2_2 optimismFiatTokenV2_2
+        OptimismMintableFiatTokenV2_2 optimismMintableFiatTokenV2_2
     ) external {
-        address l2StandardBridge = optimismFiatTokenV2_2.bridge();
+        address l2StandardBridge = optimismMintableFiatTokenV2_2.bridge();
         if (l2StandardBridge == address(0)) {
             revert("Expected no-zero bridge address");
         }
         MasterMinter masterMinter = MasterMinter(
-            optimismFiatTokenV2_2.masterMinter()
+            optimismMintableFiatTokenV2_2.masterMinter()
         );
 
         vm.startBroadcast(masterMinterOwner);

test/helpers/index.ts

@@ -26,6 +26,7 @@ import {
   FiatTokenV2_1Instance,
   FiatTokenV2_2Instance,
   FiatTokenV2Instance,
+  OptimismMintableFiatTokenV2_2Instance,
 } from "../../@types/generated";
 import _ from "lodash";
 
@@ -140,7 +141,8 @@ export async function initializeToVersion(
     | FiatTokenV1_1Instance
     | FiatTokenV2Instance
     | FiatTokenV2_1Instance
-    | FiatTokenV2_2Instance,
+    | FiatTokenV2_2Instance
+    | OptimismMintableFiatTokenV2_2Instance,
   version: "1" | "1.1" | "2" | "2.1" | "2.2",
   fiatTokenOwner: string,
   lostAndFound: string,

test/helpers/storageSlots.behavior.ts

@@ -26,7 +26,9 @@ const FiatTokenV1_1 = artifacts.require("FiatTokenV1_1");
 const FiatTokenV2 = artifacts.require("FiatTokenV2");
 const FiatTokenV2_1 = artifacts.require("FiatTokenV2_1");
 const FiatTokenV2_2 = artifacts.require("FiatTokenV2_2");
-const OptimismFiatTokenV2_2 = artifacts.require("OptimismFiatTokenV2_2");
+const OptimismMintableFiatTokenV2_2 = artifacts.require(
+  "OptimismMintableFiatTokenV2_2"
+);
 
 export const STORAGE_SLOT_NUMBERS = {
   _deprecatedBlacklisted: 3,
@@ -117,7 +119,7 @@ export function usesOriginalStorageSlotPositions<
       }
       if (version >= 2.2) {
         const proxyAsFiatTokenV2_2 = constructorArgs
-          ? await OptimismFiatTokenV2_2.at(proxy.address)
+          ? await OptimismMintableFiatTokenV2_2.at(proxy.address)
           : await FiatTokenV2_2.at(proxy.address);
         await proxyAsFiatTokenV2_2.initializeV2_2([], symbol);
       }

test/misc/gas.ts

@@ -119,13 +119,17 @@ describe(`gas costs for version ${TARGET_VERSION}`, () => {
   });
 
   it("burn() entire balance", async () => {
-    const tx = await fiatToken.burn(entireBalance, { from: fiatTokenOwner });
-    console.log(consoleMessage, tx.receipt.gasUsed);
+    if ("burn" in fiatToken) {
+      const tx = await fiatToken.burn(entireBalance, { from: fiatTokenOwner });
+      console.log(consoleMessage, tx.receipt.gasUsed);
+    }
   });
 
   it("burn() partial balance", async () => {
-    const tx = await fiatToken.burn(partialBalance, { from: fiatTokenOwner });
-    console.log(consoleMessage, tx.receipt.gasUsed);
+    if ("burn" in fiatToken) {
+      const tx = await fiatToken.burn(partialBalance, { from: fiatTokenOwner });
+      console.log(consoleMessage, tx.receipt.gasUsed);
+    }
   });
 
   it("transfer() where both parties have a balance before and after", async () => {

test/v2/OptimismFiatTokenV2_2.test.ts

@@ -19,7 +19,7 @@
 import BN from "bn.js";
 import {
   AnyFiatTokenV2Instance,
-  OptimismFiatTokenV2_2InstanceExtended,
+  OptimismMintableFiatTokenV2_2InstanceExtended,
 } from "../../@types/AnyFiatTokenV2Instance";
 import {
   expectRevert,
@@ -51,16 +51,18 @@ import { behavesLikeFiatTokenV22 } from "./v2_2.behavior";
 
 const FiatTokenProxy = artifacts.require("FiatTokenProxy");
 const FiatTokenV2_1 = artifacts.require("FiatTokenV2_1");
-const OptimismFiatTokenV2_2 = artifacts.require("OptimismFiatTokenV2_2");
+const OptimismMintableFiatTokenV2_2 = artifacts.require(
+  "OptimismMintableFiatTokenV2_2"
+);
 
-describe("OptimismFiatTokenV2_2", () => {
+describe("OptimismMintableFiatTokenV2_2", () => {
   const newSymbol = "USDCUSDC";
   const fiatTokenOwner = HARDHAT_ACCOUNTS[9];
   const lostAndFound = HARDHAT_ACCOUNTS[2];
   const proxyOwnerAccount = HARDHAT_ACCOUNTS[14];
   const l1RemoteToken = "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48";
 
-  let fiatToken: OptimismFiatTokenV2_2InstanceExtended;
+  let fiatToken: OptimismMintableFiatTokenV2_2InstanceExtended;
 
   const getFiatToken = (
     signatureBytesType: SignatureBytesType
@@ -73,11 +75,11 @@ describe("OptimismFiatTokenV2_2", () => {
 
   before(async () => {
     await linkLibraryToTokenContract(FiatTokenV2_1);
-    await linkLibraryToTokenContract(OptimismFiatTokenV2_2);
+    await linkLibraryToTokenContract(OptimismMintableFiatTokenV2_2);
   });
 
   beforeEach(async () => {
-    fiatToken = await OptimismFiatTokenV2_2.new(l1RemoteToken);
+    fiatToken = await OptimismMintableFiatTokenV2_2.new(l1RemoteToken);
     await initializeToVersion(fiatToken, "2.1", fiatTokenOwner, lostAndFound);
   });
 
@@ -154,7 +156,9 @@ describe("OptimismFiatTokenV2_2", () => {
       });
 
       // Validate that isBlacklisted returns true for every accountsToBlacklist.
-      const _proxyAsV2_2 = await OptimismFiatTokenV2_2.at(_proxy.address);
+      const _proxyAsV2_2 = await OptimismMintableFiatTokenV2_2.at(
+        _proxy.address
+      );
       const areAccountsBlacklisted = await Promise.all(
         accountsToBlacklist.map((account) =>
           _proxyAsV2_2.isBlacklisted(account)
@@ -216,7 +220,7 @@ describe("OptimismFiatTokenV2_2", () => {
     behavesLikeFiatTokenV22(getFiatToken(SignatureBytesType.Packed));
     console.log("before");
     usesOriginalStorageSlotPositions({
-      Contract: OptimismFiatTokenV2_2,
+      Contract: OptimismMintableFiatTokenV2_2,
       version: 2.2,
       constructorArgs: [l1RemoteToken],
     });
@@ -240,7 +244,7 @@ describe("OptimismFiatTokenV2_2", () => {
  * here we re-assign the overloaded method definition to the method name shorthand.
  */
 export function initializeOverloadedMethods(
-  fiatToken: OptimismFiatTokenV2_2InstanceExtended,
+  fiatToken: OptimismMintableFiatTokenV2_2InstanceExtended,
   signatureBytesType: SignatureBytesType
 ): void {
   if (signatureBytesType == SignatureBytesType.Unpacked) {