Remove DOMAIN_SEPARATOR from Votes and update docs examples (OpenZeppelin#4297)

Co-authored-by: Qiwei Yang <yangqiwei97@gmail.com>
Co-authored-by: Hadrien Croubois <hadrien.croubois@gmail.com>

Author: 3 people

.changeset/silly-bees-beam.md

@@ -2,4 +2,6 @@
 'openzeppelin-solidity': major
 ---
 
-`ERC20Votes`: Changed internal vote accounting to reusable `Votes` module previously used by `ERC721Votes`. Removed implicit `ERC20Permit` inheritance. [#3816](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3816)
+`ERC20Votes`: Changed internal vote accounting to reusable `Votes` module previously used by `ERC721Votes`. Removed implicit `ERC20Permit` inheritance. Note that the `DOMAIN_SEPARATOR` getter was previously guaranteed to be available for `ERC20Votes` contracts, but is no longer available unless `ERC20Permit` is explicitly used; ERC-5267 support is included in `ERC20Votes` with `EIP712` and is recommended as an alternative.
+
+pr: #3816

.github/workflows/checks.yml

@@ -13,6 +13,9 @@ concurrency:
   group: checks-${{ github.ref }}
   cancel-in-progress: true
 
+env:
+  NODE_OPTIONS: --max_old_space_size=5120
+
 jobs:
   lint:
     runs-on: ubuntu-latest
@@ -26,7 +29,6 @@ jobs:
     runs-on: ubuntu-latest
     env:
       FORCE_COLOR: 1
-      NODE_OPTIONS: --max_old_space_size=4096
       GAS: true
     steps:
       - uses: actions/checkout@v3
@@ -57,8 +59,6 @@ jobs:
         run: bash scripts/upgradeable/transpile.sh
       - name: Run tests
         run: npm run test
-        env:
-          NODE_OPTIONS: --max_old_space_size=4096
       - name: Check linearisation of the inheritance graph
         run: npm run test:inheritance
       - name: Check storage layout
@@ -86,8 +86,6 @@ jobs:
       - name: Set up environment
         uses: ./.github/actions/setup
       - run: npm run coverage
-        env:
-          NODE_OPTIONS: --max_old_space_size=4096
       - uses: codecov/codecov-action@v3
         with:
           token: ${{ secrets.CODECOV_TOKEN }}

contracts/governance/utils/Votes.sol

@@ -225,14 +225,6 @@ abstract contract Votes is Context, EIP712, Nonces, IERC5805 {
         return a - b;
     }
 
-    /**
-     * @dev Returns the contract's {EIP712} domain separator.
-     */
-    // solhint-disable-next-line func-name-mixedcase
-    function DOMAIN_SEPARATOR() external view returns (bytes32) {
-        return _domainSeparatorV4();
-    }
-
     /**
      * @dev Must return the voting units held by an account.
      */

contracts/mocks/docs/governance/MyGovernor.sol

@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.19;
+
+import "../../../governance/Governor.sol";
+import "../../../governance/compatibility/GovernorCompatibilityBravo.sol";
+import "../../../governance/extensions/GovernorVotes.sol";
+import "../../../governance/extensions/GovernorVotesQuorumFraction.sol";
+import "../../../governance/extensions/GovernorTimelockControl.sol";
+
+contract MyGovernor is
+    Governor,
+    GovernorCompatibilityBravo,
+    GovernorVotes,
+    GovernorVotesQuorumFraction,
+    GovernorTimelockControl
+{
+    constructor(
+        IVotes _token,
+        TimelockController _timelock
+    ) Governor("MyGovernor") GovernorVotes(_token) GovernorVotesQuorumFraction(4) GovernorTimelockControl(_timelock) {}
+
+    function votingDelay() public pure override returns (uint256) {
+        return 7200; // 1 day
+    }
+
+    function votingPeriod() public pure override returns (uint256) {
+        return 50400; // 1 week
+    }
+
+    function proposalThreshold() public pure override returns (uint256) {
+        return 0;
+    }
+
+    // The functions below are overrides required by Solidity.
+
+    function state(
+        uint256 proposalId
+    ) public view override(Governor, IGovernor, GovernorTimelockControl) returns (ProposalState) {
+        return super.state(proposalId);
+    }
+
+    function propose(
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        string memory description
+    ) public override(Governor, GovernorCompatibilityBravo, IGovernor) returns (uint256) {
+        return super.propose(targets, values, calldatas, description);
+    }
+
+    function cancel(
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        bytes32 descriptionHash
+    ) public override(Governor, GovernorCompatibilityBravo, IGovernor) returns (uint256) {
+        return super.cancel(targets, values, calldatas, descriptionHash);
+    }
+
+    function _execute(
+        uint256 proposalId,
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        bytes32 descriptionHash
+    ) internal override(Governor, GovernorTimelockControl) {
+        super._execute(proposalId, targets, values, calldatas, descriptionHash);
+    }
+
+    function _cancel(
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        bytes32 descriptionHash
+    ) internal override(Governor, GovernorTimelockControl) returns (uint256) {
+        return super._cancel(targets, values, calldatas, descriptionHash);
+    }
+
+    function _executor() internal view override(Governor, GovernorTimelockControl) returns (address) {
+        return super._executor();
+    }
+
+    function supportsInterface(
+        bytes4 interfaceId
+    ) public view override(Governor, IERC165, GovernorTimelockControl) returns (bool) {
+        return super.supportsInterface(interfaceId);
+    }
+}

contracts/mocks/docs/governance/MyToken.sol

@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.19;
+
+import "../../../token/ERC20/ERC20.sol";
+import "../../../token/ERC20/extensions/ERC20Permit.sol";
+import "../../../token/ERC20/extensions/ERC20Votes.sol";
+
+contract MyToken is ERC20, ERC20Permit, ERC20Votes {
+    constructor() ERC20("MyToken", "MTK") ERC20Permit("MyToken") {}
+
+    // The functions below are overrides required by Solidity.
+
+    function _update(address from, address to, uint256 amount) internal override(ERC20, ERC20Votes) {
+        super._update(from, to, amount);
+    }
+
+    function nonces(address owner) public view virtual override(ERC20Permit, Nonces) returns (uint256) {
+        return super.nonces(owner);
+    }
+}

contracts/mocks/docs/governance/MyTokenTimestampBased.sol

@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.19;
+
+import "../../../token/ERC20/ERC20.sol";
+import "../../../token/ERC20/extensions/ERC20Permit.sol";
+import "../../../token/ERC20/extensions/ERC20Votes.sol";
+
+contract MyTokenTimestampBased is ERC20, ERC20Permit, ERC20Votes {
+    constructor() ERC20("MyTokenTimestampBased", "MTK") ERC20Permit("MyTokenTimestampBased") {}
+
+    // Overrides IERC6372 functions to make the token & governor timestamp-based
+
+    function clock() public view override returns (uint48) {
+        return uint48(block.timestamp);
+    }
+
+    // solhint-disable-next-line func-name-mixedcase
+    function CLOCK_MODE() public pure override returns (string memory) {
+        return "mode=timestamp";
+    }
+
+    // The functions below are overrides required by Solidity.
+
+    function _update(address from, address to, uint256 amount) internal override(ERC20, ERC20Votes) {
+        super._update(from, to, amount);
+    }
+
+    function nonces(address owner) public view virtual override(ERC20Permit, Nonces) returns (uint256) {
+        return super.nonces(owner);
+    }
+}

contracts/mocks/docs/governance/MyTokenWrapped.sol

@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.19;
+
+import "../../../token/ERC20/ERC20.sol";
+import "../../../token/ERC20/extensions/ERC20Permit.sol";
+import "../../../token/ERC20/extensions/ERC20Votes.sol";
+import "../../../token/ERC20/extensions/ERC20Wrapper.sol";
+
+contract MyTokenWrapped is ERC20, ERC20Permit, ERC20Votes, ERC20Wrapper {
+    constructor(
+        IERC20 wrappedToken
+    ) ERC20("MyTokenWrapped", "MTK") ERC20Permit("MyTokenWrapped") ERC20Wrapper(wrappedToken) {}
+
+    // The functions below are overrides required by Solidity.
+
+    function decimals() public view override(ERC20, ERC20Wrapper) returns (uint8) {
+        return super.decimals();
+    }
+
+    function _update(address from, address to, uint256 amount) internal override(ERC20, ERC20Votes) {
+        super._update(from, to, amount);
+    }
+
+    function nonces(address owner) public view virtual override(ERC20Permit, Nonces) returns (uint256) {
+        return super.nonces(owner);
+    }
+}

contracts/token/ERC20/extensions/ERC20Permit.sol

@@ -66,7 +66,7 @@ abstract contract ERC20Permit is ERC20, IERC20Permit, EIP712, Nonces {
      * @dev See {IERC20Permit-DOMAIN_SEPARATOR}.
      */
     // solhint-disable-next-line func-name-mixedcase
-    function DOMAIN_SEPARATOR() external view override returns (bytes32) {
+    function DOMAIN_SEPARATOR() external view virtual override returns (bytes32) {
         return _domainSeparatorV4();
     }
 }