WIP Fix cached chain id in domain separator

contracts/v2/EIP2612.sol

@@ -78,7 +78,7 @@ abstract contract EIP2612 is AbstractFiatTokenV2, EIP712Domain {
             deadline
         );
         require(
-            EIP712.recover(DOMAIN_SEPARATOR, v, r, s, data) == owner,
+            EIP712.recover(_domainSeparator(), v, r, s, data) == owner,
             "EIP2612: invalid signature"
         );
 

contracts/v2/EIP3009.sol

@@ -109,7 +109,7 @@ abstract contract EIP3009 is AbstractFiatTokenV2, EIP712Domain {
             nonce
         );
         require(
-            EIP712.recover(DOMAIN_SEPARATOR, v, r, s, data) == from,
+            EIP712.recover(_domainSeparator(), v, r, s, data) == from,
             "FiatTokenV2: invalid signature"
         );
 
@@ -155,7 +155,7 @@ abstract contract EIP3009 is AbstractFiatTokenV2, EIP712Domain {
             nonce
         );
         require(
-            EIP712.recover(DOMAIN_SEPARATOR, v, r, s, data) == from,
+            EIP712.recover(_domainSeparator(), v, r, s, data) == from,
             "FiatTokenV2: invalid signature"
         );
 
@@ -186,7 +186,7 @@ abstract contract EIP3009 is AbstractFiatTokenV2, EIP712Domain {
             nonce
         );
         require(
-            EIP712.recover(DOMAIN_SEPARATOR, v, r, s, data) == authorizer,
+            EIP712.recover(_domainSeparator(), v, r, s, data) == authorizer,
             "FiatTokenV2: invalid signature"
         );
 

contracts/v2/EIP712Domain.sol

@@ -28,8 +28,19 @@ pragma solidity 0.6.12;
  * @title EIP712 Domain
  */
 contract EIP712Domain {
+
+    // was originally DOMAIN_SEPARATOR
+    // but that has been moved to a method so we can override it in V2_2+
+    bytes32 internal  _CACHED_DOMAIN_SEPARATOR;
+
     /**
      * @dev EIP712 Domain Separator
      */
-    bytes32 public DOMAIN_SEPARATOR;
+    function DOMAIN_SEPARATOR() external view returns (bytes32) {
+        return _domainSeparator();
+    }
+
+    function _domainSeparator() internal virtual view returns (bytes32) {
+        return _CACHED_DOMAIN_SEPARATOR;
+    }
 }

contracts/v2/FiatTokenV2.sol

@@ -46,7 +46,7 @@ contract FiatTokenV2 is FiatTokenV1_1, EIP3009, EIP2612 {
         // solhint-disable-next-line reason-string
         require(initialized && _initializedVersion == 0);
         name = newName;
-        DOMAIN_SEPARATOR = EIP712.makeDomainSeparator(newName, "2");
+        _CACHED_DOMAIN_SEPARATOR = EIP712.makeDomainSeparator(newName, "2");
         _initializedVersion = 1;
     }
 

contracts/v2/FiatTokenV2_2.sol

@@ -0,0 +1,67 @@
+/**
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright (c) 2018-2023 CENTRE SECZ
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+pragma solidity 0.6.12;
+
+import { FiatTokenV2_1 } from "./FiatTokenV2_1.sol";
+import { EIP712 } from "../util/EIP712.sol";
+
+// solhint-disable func-name-mixedcase
+
+/**
+ * @title FiatToken V2.1
+ * @notice ERC20 Token backed by fiat reserves, version 2.1
+ */
+contract FiatTokenV2_2 is FiatTokenV2_1 {
+
+    uint256 private _CACHED_CHAIN_ID;
+
+    /**
+     * @notice Initialize v2.2
+     */
+    function initializeV2_2() external {
+        // solhint-disable-next-line reason-string
+        require(_initializedVersion == 2);
+
+        _CACHED_CHAIN_ID = chainid();
+
+        _initializedVersion = 3;
+    }
+
+    function chainid() internal view returns (uint256) {
+        uint256 chainId;
+        assembly {
+            chainId := chainid()
+        }
+        return chainId;
+    }
+
+    function _domainSeparator() internal override view returns (bytes32) {
+        if (_CACHED_CHAIN_ID == chainid()) {
+            return _CACHED_DOMAIN_SEPARATOR;
+        } else {
+            return EIP712.makeDomainSeparator(name, "2");
+        }
+    }
+}

test/helpers/storageSlots.behavior.ts

@@ -4,6 +4,8 @@ import { FiatTokenProxyInstance } from "../../@types/generated";
 const FiatTokenProxy = artifacts.require("FiatTokenProxy");
 const FiatTokenV1 = artifacts.require("FiatTokenV1");
 const FiatTokenV1_1 = artifacts.require("FiatTokenV1_1");
+const FiatTokenV2 = artifacts.require("FiatTokenV2");
+const FiatTokenV2_1 = artifacts.require("FiatTokenV2_1");
 
 export function usesOriginalStorageSlotPositions<
   T extends Truffle.ContractInstance
@@ -35,10 +37,12 @@ export function usesOriginalStorageSlotPositions<
       alice,
       bob,
       charlie,
+      lostAndFound,
     ] = accounts;
 
     let fiatToken: T;
     let proxy: FiatTokenProxyInstance;
+    let domainSeparator : String;
 
     beforeEach(async () => {
       fiatToken = await Contract.new();
@@ -72,6 +76,15 @@ export function usesOriginalStorageSlotPositions<
           from: owner,
         });
       }
+      if (version >= 2) {
+        const proxyAsFiatTokenV2 = await FiatTokenV2.at(proxy.address);
+        await proxyAsFiatTokenV2.initializeV2(name);
+        domainSeparator = await proxyAsFiatTokenV2.DOMAIN_SEPARATOR();
+      }
+      if (version >= 2.1) {
+        const proxyAsFiatTokenV2_1 = await FiatTokenV2_1.at(proxy.address);
+        await proxyAsFiatTokenV2_1.initializeV2_1(lostAndFound);
+      }
     });
 
     it("retains original storage slots 0 through 13", async () => {
@@ -132,6 +145,12 @@ export function usesOriginalStorageSlotPositions<
         expect(parseAddress(slot)).to.equal(rescuer);
       });
     }
+    if (version >= 2) {
+      it("retains slot 15 for DOMAIN_SEPARATOR", async()=> {
+        const slot = await readSlot(proxy.address, 15);
+        expect("0x" + slot).to.equal(domainSeparator);
+      });
+    }
 
     it("retains original storage slots for blacklisted mapping", async () => {
       // blacklisted[alice]

test/v2/FiatTokenV2_2.test.ts

@@ -0,0 +1,43 @@
+import { FiatTokenV22Instance } from "../../@types/generated";
+import { expectRevert } from "../helpers";
+import { behavesLikeFiatTokenV2 } from "./FiatTokenV2.test";
+
+const FiatTokenV2_2 = artifacts.require("FiatTokenV2_2");
+
+contract("FiatTokenV2_2", (accounts) => {
+  const fiatTokenOwner = accounts[9];
+  let fiatToken: FiatTokenV22Instance;
+
+  beforeEach(async () => {
+    fiatToken = await FiatTokenV2_2.new();
+    await fiatToken.initialize(
+      "USD Coin",
+      "USDC",
+      "USD",
+      6,
+      fiatTokenOwner,
+      fiatTokenOwner,
+      fiatTokenOwner,
+      fiatTokenOwner
+    );
+    await fiatToken.initializeV2("USD Coin", { from: fiatTokenOwner });
+    const [, , lostAndFound] = accounts;
+    await fiatToken.initializeV2_1(lostAndFound);
+    await fiatToken.initializeV2_2();
+  });
+
+  behavesLikeFiatTokenV2(accounts, () => fiatToken, fiatTokenOwner);
+
+  describe("initializeV2_2", () => {
+    const [, user, lostAndFound] = accounts;
+
+    beforeEach(async () => {
+    });
+
+    it("disallows calling initializeV2_2 twice", async () => {
+      await expectRevert(
+        fiatToken.initializeV2_2()
+      );
+    });
+  });
+});