Transpile 7bce2b72

.codecov.yml

@@ -0,0 +1,11 @@
+comment: off
+github_checks:
+  annotations: false
+coverage:
+  status:
+    patch:
+      default:
+        target: 95%
+    project:
+      default:
+        threshold: 1%

.editorconfig

@@ -0,0 +1,21 @@
+# EditorConfig is awesome: https://EditorConfig.org
+
+# top-most EditorConfig file
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_style = space
+insert_final_newline = true
+trim_trailing_whitespace = false
+max_line_length = 120
+
+[*.sol]
+indent_size = 4
+
+[*.js]
+indent_size = 2
+
+[*.adoc]
+max_line_length = 0

.eslintrc

@@ -0,0 +1,64 @@
+{
+  "extends" : [
+    "standard",
+    "plugin:promise/recommended",
+  ],
+  "plugins": [
+    "mocha-no-only",
+    "promise",
+  ],
+  "env": {
+    "browser" : true,
+    "node"    : true,
+    "mocha"   : true,
+    "jest"    : true,
+  },
+  "globals" : {
+    "artifacts": false,
+    "contract": false,
+    "assert": false,
+    "web3": false,
+    "usePlugin": false,
+    "extendEnvironment": false,
+  },
+  "rules": {
+
+    // Strict mode
+    "strict": ["error", "global"],
+
+    // Code style
+    "array-bracket-spacing": ["off"],
+    "camelcase": ["error", {"properties": "always"}],
+    "comma-dangle": ["error", "always-multiline"],
+    "comma-spacing": ["error", {"before": false, "after": true}],
+    "dot-notation": ["error", {"allowKeywords": true, "allowPattern": ""}],
+    "eol-last": ["error", "always"],
+    "eqeqeq": ["error", "smart"],
+    "generator-star-spacing": ["error", "before"],
+    "indent": ["error", 2],
+    "linebreak-style": ["error", "unix"],
+    "max-len": ["error", 120, 2],
+    "no-debugger": "off",
+    "no-dupe-args": "error",
+    "no-dupe-keys": "error",
+    "no-mixed-spaces-and-tabs": ["error", "smart-tabs"],
+    "no-redeclare": ["error", {"builtinGlobals": true}],
+    "no-trailing-spaces": ["error", { "skipBlankLines": false }],
+    "no-undef": "error",
+    "no-use-before-define": "off",
+    "no-var": "error",
+    "object-curly-spacing": ["error", "always"],
+    "prefer-const": "error",
+    "quotes": ["error", "single"],
+    "semi": ["error", "always"],
+    "space-before-function-paren": ["error", "always"],
+
+    "mocha-no-only/mocha-no-only": ["error"],
+
+    "promise/always-return": "off",
+    "promise/avoid-new": "off",
+  },
+  "parserOptions": {
+    "ecmaVersion": 2018
+  }
+}

.gitattributes

@@ -0,0 +1 @@
+*.sol linguist-language=Solidity

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,21 @@
+---
+name: Bug report
+about: Report a bug in OpenZeppelin Contracts
+
+---
+
+<!-- Briefly describe the issue you're experiencing. Tell us what you were trying to do and what happened instead. -->
+
+<!-- Remember, this is not a place to ask for help debugging code. For that, we welcome you in the OpenZeppelin Community Forum: https://forum.openzeppelin.com/. -->
+
+**💻 Environment**
+
+<!-- Tell us what version of OpenZeppelin Contracts you're using, and how you're using it: Truffle, Remix, etc. -->
+
+**📝 Details**
+
+<!-- Describe the problem you have been experiencing in more detail. Include as much information as you think is relevant. Keep in mind that transactions can fail for many reasons; context is key here. -->
+
+**🔢 Code to reproduce bug**
+
+<!-- We will be able to better help if you provide a minimal example that triggers the bug. -->

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,4 @@
+contact_links:
+  - name: Support request
+    url: https://forum.openzeppelin.com/c/support/contracts/18
+    about: Ask the community in the Community Forum

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,14 @@
+---
+name: Feature request
+about: Suggest an idea for OpenZeppelin Contracts
+
+---
+
+**🧐 Motivation**
+<!-- Is your feature request related to a specific problem? Is it just a crazy idea? Tell us about it! -->
+
+**📝 Details**
+<!-- Please describe your feature request in detail. -->
+
+<!-- Make sure that you have reviewed the OpenZeppelin Contracts Contributor Guidelines. -->
+<!-- https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/CONTRIBUTING.md -->

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,20 @@
+<!-- Thank you for your interest in contributing to OpenZeppelin! -->
+
+<!-- Consider opening an issue for discussion prior to submitting a PR. -->
+<!-- New features will be merged faster if they were first discussed and designed with the team. -->
+
+Fixes #???? <!-- Fill in with issue number -->
+
+<!-- Describe the changes introduced in this pull request. -->
+<!-- Include any context necessary for understanding the PR's purpose. -->
+
+
+#### PR Checklist
+
+<!-- Before merging the pull request all of the following must be complete. -->
+<!-- Feel free to submit a PR or Draft PR even if some items are pending. -->
+<!-- Some of the items may not apply. -->
+
+- [ ] Tests
+- [ ] Documentation
+- [ ] Changelog entry

.github/workflows/merge-upstream.yml

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+name: Merge upstream
+
+on:
+  push:
+    branches: [patches]
+  workflow_dispatch: {}
+  repository_dispatch:
+    types: [Update]
+    # client_payload: { ref: string }
+
+concurrency:
+  group: merge-${{ github.event.client_payload.ref || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  merge:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          ref: patches
+          fetch-depth: 0
+          ssh-key: ${{ secrets.DEPLOY_KEY }}
+      - run: bash scripts/upgradeable/git-user-config.sh
+      - run: bash scripts/upgradeable/merge-upstream.sh
+        env:
+          REF: ${{ github.event.client_payload.ref || github.ref}}
+      - run: git push origin HEAD

.github/workflows/test.yml

@@ -0,0 +1,35 @@
+name: Test
+
+on:
+  push:
+    branches:
+      - master
+      - release-v*
+  pull_request: {}
+  workflow_dispatch: {}
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-node@v2
+        with:
+          node-version: 12.x
+      - uses: actions/cache@v2
+        id: cache
+        with:
+          path: '**/node_modules'
+          key: npm-v2-${{ hashFiles('**/package-lock.json') }}
+          restore-keys: npm-v2-
+      - run: npm ci
+        if: steps.cache.outputs.cache-hit != 'true'
+      - run: bash scripts/upgradeable/transpile.sh
+        if: github.event_name == 'pull_request'
+      - run: npm run test
+        env:
+          FORCE_COLOR: 1
+          ENABLE_GAS_REPORT: true
+      - run: npm run test:inheritance 
+      - name: Print gas report
+        run: cat gas-report.txt

.github/workflows/transpile.yml

@@ -0,0 +1,36 @@
+name: Transpile
+
+on:
+  workflow_dispatch: {}
+  push:
+    branches: [patched/*]
+
+concurrency:
+  group: transpile-${{ github.ref_name }}
+  cancel-in-progress: true
+
+jobs:
+  transpile:
+    runs-on: ubuntu-latest
+    if: startsWith(github.ref, 'refs/heads/patched/')
+    steps:
+      - run: echo ::set-output name=name::"${GITHUB_REF#refs/heads/patched/}"
+        id: branch
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+          ssh-key: ${{ secrets.DEPLOY_KEY }}
+      - uses: actions/setup-node@v1
+        with:
+          node-version: 12.x
+      - uses: actions/cache@v2
+        id: cache
+        with:
+          path: '**/node_modules'
+          key: npm-v2-${{ hashFiles('**/package-lock.json') }}
+          restore-keys: npm-v2-
+      - run: npm ci
+        if: steps.cache.outputs.cache-hit != 'true'
+      - run: bash scripts/upgradeable/git-user-config.sh
+      - run: bash scripts/upgradeable/transpile-onto.sh ${{ steps.branch.outputs.name }} origin/${{ steps.branch.outputs.name }}
+      - run: git push origin ${{ steps.branch.outputs.name }}

.gitignore

@@ -0,0 +1,64 @@
+*.swp
+*.swo
+
+# Logs
+logs
+*.log
+
+# Runtime data
+pids
+*.pid
+*.seed
+allFiredEvents
+scTopics
+
+# Coverage directory used by tools like istanbul
+coverage
+coverage.json
+coverageEnv
+
+# node-waf configuration
+.lock-wscript
+
+# Dependency directory
+node_modules
+
+# Debug log from npm
+npm-debug.log
+
+# local env variables
+.env
+
+# truffle build directory
+build/
+
+# macOS
+.DS_Store
+
+# truffle
+.node-xmlhttprequest-*
+
+# IntelliJ IDE
+.idea
+
+# docs artifacts
+docs/modules/api
+
+# only used to package @openzeppelin/contracts
+contracts/build/
+contracts/README.md
+
+# temporary artifact from solidity-coverage
+allFiredEvents
+.coverage_artifacts
+.coverage_cache
+.coverage_contracts
+
+# hardhat
+cache
+artifacts
+
+# Certora
+.certora*
+.last_confs
+certora_*

.mocharc.js

@@ -0,0 +1,4 @@
+module.exports = {
+  require: 'hardhat/register',
+  timeout: 4000,
+};

.prettierrc

@@ -0,0 +1,11 @@
+{
+  "overrides": [
+    {
+      "files": "*.sol",
+      "options": {
+        "printWidth": 120,
+        "explicitTypes": "always"
+      }
+    }
+  ]
+}

.solcover.js

@@ -0,0 +1,15 @@
+module.exports = {
+    norpc: true,
+    testCommand: 'npm test',
+    compileCommand: 'npm run compile',
+    skipFiles: [
+        'mocks',
+    ],
+    providerOptions: {
+        default_balance_ether: '10000000000000000000000000',
+    },
+    mocha: {
+        fgrep: '[skip-on-coverage]',
+        invert: true,
+    },
+}

.solhint.json

@@ -0,0 +1,14 @@
+{
+  "rules": {
+    "no-unused-vars": "error",
+    "const-name-snakecase": "error",
+    "contract-name-camelcase": "error",
+    "event-name-camelcase": "error",
+    "func-name-mixedcase": "error",
+    "func-param-name-mixedcase": "error",
+    "modifier-name-mixedcase": "error",
+    "private-vars-leading-underscore": "error",
+    "var-name-mixedcase": "error",
+    "imports-on-top": "error"
+  }
+}

CHANGELOG.md

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+# Changelog
+
+## 4.5.0
+
+ * `ERC2891`: add implementation of the royalty standard, and the respective extensions for `ERC721` and `ERC1155`. ([#3012](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3012))
+ * `GovernorTimelockControl`: improve the `state()` function to have it reflect cases where a proposal has been canceled directly on the timelock. ([#2977](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2977))
+ * `Math`: add a `abs(int256)` method that returns the unsigned absolute value of a signed value. ([#2984](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2984))
+ * Preset contracts are now deprecated in favor of [Contracts Wizard](https://wizard.openzeppelin.com). ([#2986](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2986))
+ * `Governor`: add a relay function to help recover assets sent to a governor that is not its own executor (e.g. when using a timelock). ([#2926](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2926))
+ * `GovernorPreventLateQuorum`: add new module to ensure a minimum voting duration is available after the quorum is reached. ([#2973](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2973))
+ * `ERC721`: improved revert reason when transferring from wrong owner. ([#2975](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2975))
+ * `Votes`: Added a base contract for vote tracking with delegation. ([#2944](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2944))
+ * `ERC721Votes`: Added an extension of ERC721 enabled with vote tracking and delegation. ([#2944](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2944))
+ * `ERC2771Context`: use immutable storage to store the forwarder address, no longer an issue since Solidity >=0.8.8 allows reading immutable variables in the constructor. ([#2917](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2917))
+ * `Base64`: add a library to parse bytes into base64 strings using `encode(bytes memory)` function, and provide examples to show how to use to build URL-safe `tokenURIs`. ([#2884](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/#2884))
+ * `ERC20`: reduce allowance before triggering transfer. ([#3056](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/#3056))
+ * `ERC20`: do not update allowance on `transferFrom` when allowance is `type(uint256).max`. ([#3085](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/#3085))
+ * `ERC777`: do not update allowance on `transferFrom` when allowance is `type(uint256).max`. ([#3085](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/#3085))
+ * `SignedMath`: a new signed version of the Math library with `max`, `min`,  and `average`. ([#2686](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2686))
+ * `ERC1967Upgrade`: Refactor the secure upgrade to use `ERC1822` instead of the previous rollback mechanism. This reduces code complexity and attack surface with similar security guarantees. ([#3021](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3021))
+ * `UUPSUpgradeable`: Add `ERC1822` compliance to support the updated secure upgrade mechanism. ([#3021](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3021))
+ * Some more functions have been made virtual to customize them via overrides. In many cases this will not imply that other functions in the contract will automatically adapt to the overridden definitions. People who wish to override should consult the source code to understand the impact and if they need to override any additional functions to achieve the desired behavior.
+
+### Breaking changes
+
+* `ERC1967Upgrade`: The function `_upgradeToAndCallSecure` was renamed to `_upgradeToAndCallUUPS`, along with the change in security mechanism described above.
+* `Address`: The Solidity pragma is increased from `^0.8.0` to `^0.8.1`. This is required by the `account.code.length` syntax that replaces inline assembly. This may require users to bump their compiler version from `0.8.0` to `0.8.1` or later. Note that other parts of the code already include stricter requirements.
+
+## 4.4.2 (2022-01-11)
+
+### Bugfixes
+ * `GovernorCompatibilityBravo`: Fix error in the encoding of calldata for proposals submitted through the compatibility interface with explicit signatures. ([#3100](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/#3100))
+
+## 4.4.1 (2021-12-14)
+
+ * `Initializable`: change the existing `initializer` modifier and add a new `onlyInitializing` modifier to prevent reentrancy risk. ([#3006](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3006))
+
+### Breaking change
+
+It is no longer possible to call an `initializer`-protected function from within another `initializer` function outside the context of a constructor. Projects using OpenZeppelin upgradeable proxies should continue to work as is, since in the common case the initializer is invoked in the constructor directly. If this is not the case for you, the suggested change is to use the new `onlyInitializing` modifier in the following way:
+
+```diff
+ contract A {
+-    function initialize() public   initializer { ... }
++    function initialize() internal onlyInitializing { ... }
+ }
+ contract B is A {
+     function initialize() public initializer {
+         A.initialize();
+     }
+ }
+```
+
+## 4.4.0 (2021-11-25)
+
+ * `Ownable`: add an internal `_transferOwnership(address)`. ([#2568](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2568))
+ * `AccessControl`: add internal `_grantRole(bytes32,address)` and `_revokeRole(bytes32,address)`. ([#2568](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2568))
+ * `AccessControl`: mark `_setupRole(bytes32,address)` as deprecated in favor of `_grantRole(bytes32,address)`. ([#2568](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2568))
+ * `AccessControlEnumerable`: hook into `_grantRole(bytes32,address)` and `_revokeRole(bytes32,address)`. ([#2946](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2946))
+ * `EIP712`: cache `address(this)` to immutable storage to avoid potential issues if a vanilla contract is used in a delegatecall context. ([#2852](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2852))
+ * Add internal `_setApprovalForAll` to `ERC721` and `ERC1155`. ([#2834](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2834))
+ * `Governor`: shift vote start and end by one block to better match Compound's GovernorBravo and prevent voting at the Governor level if the voting snapshot is not ready. ([#2892](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2892))
+ * `GovernorCompatibilityBravo`: consider quorum an inclusive rather than exclusive minimum to match Compound's GovernorBravo. ([#2974](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2974))
+ * `GovernorSettings`: a new governor module that manages voting settings updatable through governance actions. ([#2904](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2904))
+ * `PaymentSplitter`: now supports ERC20 assets in addition to Ether. ([#2858](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2858))
+ * `ECDSA`: add a variant of `toEthSignedMessageHash` for arbitrary length message hashing. ([#2865](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2865))
+ * `MerkleProof`: add a `processProof` function that returns the rebuilt root hash given a leaf and a proof. ([#2841](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2841))
+ * `VestingWallet`: new contract that handles the vesting of Ether and ERC20 tokens following a customizable vesting schedule. ([#2748](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2748))
+ * `Governor`: enable receiving Ether when a Timelock contract is not used. ([#2748](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2849))
+ * `GovernorTimelockCompound`: fix ability to use Ether stored in the Timelock contract. ([#2748](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2849))
+
+## 4.3.3
+
+ * `ERC1155Supply`: Handle `totalSupply` changes by hooking into `_beforeTokenTransfer` to ensure consistency of balances and supply during `IERC1155Receiver.onERC1155Received` calls.
+
+## 4.3.2 (2021-09-14)
+
+ * `UUPSUpgradeable`: Add modifiers to prevent `upgradeTo` and `upgradeToAndCall` being executed on any contract that is not the active ERC1967 proxy. This prevents these functions being called on implementation contracts or minimal ERC1167 clones, in particular.
+
+## 4.3.1 (2021-08-26)
+
+ * `TimelockController`: Add additional isOperationReady check.
+
+## 4.3.0 (2021-08-17)
+
+ * `ERC2771Context`: use private variable from storage to store the forwarder address. Fixes issues where `_msgSender()` was not callable from constructors. ([#2754](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2754))
+ * `EnumerableSet`: add `values()` functions that returns an array containing all values in a single call. ([#2768](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2768))
+ * `Governor`: added a modular system of `Governor` contracts based on `GovernorAlpha` and `GovernorBravo`. ([#2672](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2672))
+ * Add an `interfaces` folder containing solidity interfaces to final ERCs. ([#2517](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2517))
+ * `ECDSA`: add `tryRecover` functions that will not throw if the signature is invalid, and will return an error flag instead. ([#2661](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2661))
+ * `SignatureChecker`: Reduce gas usage of the `isValidSignatureNow` function for the "signature by EOA" case. ([#2661](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2661))
+
+## 4.2.0 (2021-06-30)
+
+ * `ERC20Votes`: add a new extension of the `ERC20` token with support for voting snapshots and delegation. ([#2632](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2632))
+ * `ERC20VotesComp`: Variant of `ERC20Votes` that is compatible with Compound's `Comp` token interface but restricts supply to `uint96`. ([#2706](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2706))
+ * `ERC20Wrapper`: add a new extension of the `ERC20` token which wraps an underlying token. Deposit and withdraw guarantee that the total supply is backed by a corresponding amount of underlying token. ([#2633](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2633))
+ * Enumerables: Improve gas cost of removal in `EnumerableSet` and `EnumerableMap`.
+ * Enumerables: Improve gas cost of lookup in `EnumerableSet` and `EnumerableMap`.
+ * `Counter`: add a reset method. ([#2678](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2678))
+ * Tokens: Wrap definitely safe subtractions in `unchecked` blocks.
+ * `Math`: Add a `ceilDiv` method for performing ceiling division.
+ * `ERC1155Supply`: add a new `ERC1155` extension that keeps track of the totalSupply of each tokenId. ([#2593](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2593))
+ * `BitMaps`: add a new `BitMaps` library that provides a storage efficient datastructure for `uint256` to `bool` mapping with contiguous keys. ([#2710](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2710))
+
+### Breaking Changes
+
+ * `ERC20FlashMint` is no longer a Draft ERC. ([#2673](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2673)))
+
+**How to update:** Change your import paths by removing the `draft-` prefix from `@openzeppelin/contracts/token/ERC20/extensions/draft-ERC20FlashMint.sol`.
+
+> See [Releases and Stability: Drafts](https://docs.openzeppelin.com/contracts/4.x/releases-stability#drafts).
+
+## 4.1.0 (2021-04-29)
+
+ * `IERC20Metadata`: add a new extended interface that includes the optional `name()`, `symbol()` and `decimals()` functions. ([#2561](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2561))
+ * `ERC777`: make reception acquirement optional in `_mint`. ([#2552](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2552))
+ * `ERC20Permit`: add a `_useNonce` to enable further usage of ERC712 signatures. ([#2565](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2565))
+ * `ERC20FlashMint`: add an implementation of the ERC3156 extension for flash-minting ERC20 tokens. ([#2543](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2543))
+ * `SignatureChecker`: add a signature verification library that supports both EOA and ERC1271 compliant contracts as signers. ([#2532](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2532))
+ * `Multicall`: add abstract contract with `multicall(bytes[] calldata data)` function to bundle multiple calls together ([#2608](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2608))
+ * `ECDSA`: add support for ERC2098 short-signatures. ([#2582](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2582))
+ * `AccessControl`: add a `onlyRole` modifier to restrict specific function to callers bearing a specific role. ([#2609](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2609))
+ * `StorageSlot`: add a library for reading and writing primitive types to specific storage slots. ([#2542](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2542))
+ * UUPS Proxies: add `UUPSUpgradeable` to implement the UUPS proxy pattern together with `EIP1967Proxy`. ([#2542](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2542))
+
+### Breaking changes
+
+This release includes two small breaking changes in `TimelockController`.
+
+1. The `onlyRole` modifier in this contract was designed to let anyone through if the role was granted to `address(0)`,
+   allowing the possibility to to make a role "open", which can be used for `EXECUTOR_ROLE`. This modifier is now
+   replaced by `AccessControl.onlyRole`, which does not have this ability. The previous behavior was moved to the
+   modifier `TimelockController.onlyRoleOrOpenRole`.
+2. It was possible to make `PROPOSER_ROLE` an open role (as described in the previous item) if it was granted to
+   `address(0)`. This would affect the `schedule`, `scheduleBatch`, and `cancel` operations in `TimelockController`.
+   This ability was removed as it does not make sense to open up the `PROPOSER_ROLE` in the same way that it does for
+   `EXECUTOR_ROLE`.
+
+## 4.0.0 (2021-03-23)
+
+ * Now targeting the 0.8.x line of Solidity compilers. For 0.6.x (resp 0.7.x) support, use version 3.4.0 (resp 3.4.0-solc-0.7) of OpenZeppelin.
+ * `Context`: making `_msgData` return `bytes calldata` instead of `bytes memory` ([#2492](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2492))
+ * `ERC20`: removed the `_setDecimals` function and the storage slot associated to decimals. ([#2502](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2502))
+ * `Strings`: addition of a `toHexString` function.  ([#2504](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2504))
+ * `EnumerableMap`: change implementation to optimize for `key → value` lookups instead of enumeration. ([#2518](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2518))
+ * `GSN`: deprecate GSNv1 support in favor of upcoming support for GSNv2. ([#2521](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2521))
+ * `ERC165`: remove uses of storage in the base ERC165 implementation. ERC165 based contracts now use storage-less virtual functions. Old behavior remains available in the `ERC165Storage` extension. ([#2505](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2505))
+ * `Initializable`: make initializer check stricter during construction. ([#2531](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2531))
+ * `ERC721`: remove enumerability of tokens from the base implementation. This feature is now provided separately through the `ERC721Enumerable` extension. ([#2511](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2511))
+ * `AccessControl`: removed enumerability by default for a more lightweight contract. It is now opt-in through `AccessControlEnumerable`. ([#2512](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2512))
+ * Meta Transactions: add `ERC2771Context` and a `MinimalForwarder` for meta-transactions. ([#2508](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2508))
+ * Overall reorganization of the contract folder to improve clarity and discoverability. ([#2503](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2503))
+ * `ERC20Capped`: optimize gas usage by enforcing the check directly in `_mint`. ([#2524](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2524))
+ * Rename `UpgradeableProxy` to `ERC1967Proxy`. ([#2547](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2547))
+ * `ERC777`: optimize the gas costs of the constructor. ([#2551](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2551))
+ * `ERC721URIStorage`: add a new extension that implements the `_setTokenURI` behavior as it was available in 3.4.0. ([#2555](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2555))
+ * `AccessControl`: added ERC165 interface detection. ([#2562](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2562))
+ * `ERC1155`: make `uri` public so overloading function can call it using super. ([#2576](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2576))
+
+### Bug fixes for beta releases
+
+ * `AccessControlEnumerable`: Fixed `renounceRole` not updating enumerable set of addresses for a role. ([#2572](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2572))
+
+### How to upgrade from 3.x
+
+Since this version has moved a few contracts to different directories, users upgrading from a previous version will need to adjust their import statements. To make this easier, the package includes a script that will migrate import statements automatically. After upgrading to the latest version of the package, run:
+
+```
+npx openzeppelin-contracts-migrate-imports
+```
+
+Make sure you're using git or another version control system to be able to recover from any potential error in our script.
+
+### How to upgrade from 4.0-beta.x
+
+Some further changes have been done between the different beta iterations. Transitions made during this period are configured in the `migrate-imports` script. Consequently, you can upgrade from any previous 4.0-beta.x version using the same script as described in the *How to upgrade from 3.x* section.
+
+## 3.4.2
+
+ * `TimelockController`: Add additional isOperationReady check.
+
+## 3.4.1 (2021-03-03)
+
+ * `ERC721`: made `_approve` an internal function (was private).
+
+## 3.4.0 (2021-02-02)
+
+ * `BeaconProxy`: added new kind of proxy that allows simultaneous atomic upgrades. ([#2411](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2411))
+ * `EIP712`: added helpers to verify EIP712 typed data signatures on chain. ([#2418](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2418))
+ * `ERC20Permit`: added an implementation of the ERC20 permit extension for gasless token approvals. ([#2237](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2237))
+ * Presets: added token presets with preminted fixed supply `ERC20PresetFixedSupply` and `ERC777PresetFixedSupply`. ([#2399](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2399))
+ * `Clones`: added a library for deploying EIP 1167 minimal proxies. ([#2449](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2449))
+ * `Context`: moved from `contracts/GSN` to `contracts/utils`. ([#2453](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2453))
+ * `PaymentSplitter`: replace usage of `.transfer()` with `Address.sendValue` for improved compatibility with smart wallets. ([#2455](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2455))
+ * `UpgradeableProxy`: bubble revert reasons from initialization calls. ([#2454](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2454))
+ * `SafeMath`: fix a memory allocation issue by adding new `SafeMath.tryOp(uint,uint)→(bool,uint)` functions. `SafeMath.op(uint,uint,string)→uint` are now deprecated. ([#2462](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2462))
+ * `EnumerableMap`: fix a memory allocation issue by adding new `EnumerableMap.tryGet(uint)→(bool,address)` functions. `EnumerableMap.get(uint)→string` is now deprecated. ([#2462](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2462))
+ * `ERC165Checker`: added batch `getSupportedInterfaces`. ([#2469](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2469))
+ * `RefundEscrow`: `beneficiaryWithdraw` will forward all available gas to the beneficiary. ([#2480](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2480))
+ * Many view and pure functions have been made virtual to customize them via overrides. In many cases this will not imply that other functions in the contract will automatically adapt to the overridden definitions. People who wish to override should consult the source code to understand the impact and if they need to override any additional functions to achieve the desired behavior.
+
+### Security Fixes
+
+ * `ERC777`: fix potential reentrancy issues for custom extensions to `ERC777`. ([#2483](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2483))
+
+If you're using our implementation of ERC777 from version 3.3.0 or earlier, and you define a custom `_beforeTokenTransfer` function that writes to a storage variable, you may be vulnerable to a reentrancy attack. If you're affected and would like assistance please write to security@openzeppelin.com. [Read more in the pull request.](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2483)
+
+## 3.3.0 (2020-11-26)
+
+ * Now supports both Solidity 0.6 and 0.7. Compiling with solc 0.7 will result in warnings. Install the `solc-0.7` tag to compile without warnings.
+ * `Address`: added `functionStaticCall`, similar to the existing `functionCall`. ([#2333](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2333))
+ * `TimelockController`: added a contract to augment access control schemes with a delay. ([#2354](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2354))
+ * `EnumerableSet`: added `Bytes32Set`, for sets of `bytes32`. ([#2395](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2395))
+
+## Upgradeable 3.2.0 (2020-11-11)
+
+ * First release of Upgradeable variant, replacing Ethereum Package variant which is now deprecated.
+
+## 3.2.2-solc-0.7 (2020-10-28)
+ * Resolve warnings introduced by Solidity 0.7.4. ([#2396](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2396))
+
+## 3.2.1-solc-0.7 (2020-09-15)
+ * `ERC777`: Remove a warning about function state visibility in Solidity 0.7. ([#2327](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2327))
+
+## 3.2.0 (2020-09-10)
+
+### New features
+ * Proxies: added the proxy contracts from OpenZeppelin SDK. ([#2335](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2335))
+
+#### Proxy changes with respect to OpenZeppelin SDK
+
+Aside from upgrading them from Solidity 0.5 to 0.6, we've changed a few minor things from the proxy contracts as they were found in OpenZeppelin SDK.
+
+- `UpgradeabilityProxy` was renamed to `UpgradeableProxy`.
+- `AdminUpgradeabilityProxy` was renamed to `TransparentUpgradeableProxy`.
+- `Proxy._willFallback` was renamed to `Proxy._beforeFallback`.
+- `UpgradeabilityProxy._setImplementation` and `AdminUpgradeabilityProxy._setAdmin` were made private.
+
+### Improvements
+ * `Address.isContract`: switched from `extcodehash` to `extcodesize` for less gas usage. ([#2311](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2311))
+
+### Breaking changes
+ * `ERC20Snapshot`: switched to using `_beforeTokenTransfer` hook instead of overriding ERC20 operations. ([#2312](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2312))
+
+This small change in the way we implemented `ERC20Snapshot` may affect users who are combining this contract with
+other ERC20 flavors, since it no longer overrides `_transfer`, `_mint`, and `_burn`. This can result in having to remove Solidity `override(...)` specifiers in derived contracts for these functions, and to instead have to add it for `_beforeTokenTransfer`. See [Using Hooks](https://docs.openzeppelin.com/contracts/3.x/extending-contracts#using-hooks) in the documentation.
+
+## 3.1.0 (2020-06-23)
+
+### New features
+ * `SafeCast`: added functions to downcast signed integers (e.g. `toInt32`), improving usability of `SignedSafeMath`. ([#2243](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2243))
+ * `functionCall`: new helpers that replicate Solidity's function call semantics, reducing the need to rely on `call`. ([#2264](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2264))
+ * `ERC1155`: added support for a base implementation, non-standard extensions and a preset contract. ([#2014](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2014), [#2230](https://github.com/OpenZeppelin/openzeppelin-contracts/issues/2230))
+
+### Improvements
+ * `ReentrancyGuard`: reduced overhead of using the `nonReentrant` modifier. ([#2171](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2171))
+ * `AccessControl`: added a `RoleAdminChanged` event to `_setAdminRole`. ([#2214](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2214))
+ * Made all `public` functions in the token preset contracts `virtual`. ([#2257](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2257))
+
+### Deprecations
+ * `SafeERC20`: deprecated `safeApprove`. ([#2268](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2268))
+
+## 3.0.2 (2020-06-08)
+
+### Improvements
+ * Added SPX license identifier to all contracts. ([#2235](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2235))
+
+## 3.0.1 (2020-04-27)
+
+### Bugfixes
+ * `ERC777`: fixed the `_approve` internal function not validating some of their arguments for non-zero addresses. ([#2213](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2213))
+
+## 3.0.0 (2020-04-20)
+
+### New features
+ * `AccessControl`: new contract for managing permissions in a system, replacement for `Ownable` and `Roles`. ([#2112](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2112))
+ * `SafeCast`: new functions to convert to and from signed and unsigned values: `toUint256` and `toInt256`. ([#2123](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2123))
+ * `EnumerableMap`: a new data structure for key-value pairs (like `mapping`) that can be iterated over. ([#2160](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2160))
+
+### Breaking changes
+ * `ERC721`: `burn(owner, tokenId)` was removed, use `burn(tokenId)` instead. ([#2125](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2125))
+ * `ERC721`: `_checkOnERC721Received` was removed. ([#2125](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2125))
+ * `ERC721`: `_transferFrom` and `_safeTransferFrom` were renamed to `_transfer` and `_safeTransfer`. ([#2162](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2162))
+ * `Ownable`: removed `_transferOwnership`. ([#2162](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2162))
+ * `PullPayment`, `Escrow`: `withdrawWithGas` was removed. The old `withdraw` function now forwards all gas. ([#2125](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2125))
+ * `Roles` was removed, use `AccessControl` as a replacement. ([#2112](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2112))
+ * `ECDSA`: when receiving an invalid signature, `recover` now reverts instead of returning the zero address. ([#2114](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2114))
+ * `Create2`: added an `amount` argument to `deploy` for contracts with `payable` constructors. ([#2117](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2117))
+ * `Pausable`: moved to the `utils` directory. ([#2122](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2122))
+ * `Strings`: moved to the `utils` directory. ([#2122](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2122))
+ * `Counters`: moved to the `utils` directory. ([#2122](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2122))
+ * `SignedSafeMath`: moved to the `math` directory. ([#2122](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2122))
+ * `ERC20Snapshot`: moved to the `token/ERC20` directory. `snapshot` was changed into an `internal` function. ([#2122](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2122))
+ * `Ownable`: moved to the `access` directory. ([#2120](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2120))
+ * `Ownable`: removed `isOwner`. ([#2120](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2120))
+ * `Secondary`: removed from the library, use `Ownable` instead. ([#2120](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2120))
+ * `Escrow`, `ConditionalEscrow`, `RefundEscrow`: these now use `Ownable` instead of `Secondary`, their external API changed accordingly. ([#2120](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2120))
+ * `ERC20`: removed `_burnFrom`. ([#2119](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2119))
+ * `Address`: removed `toPayable`, use `payable(address)` instead. ([#2133](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2133))
+ * `ERC777`: `_send`, `_mint` and `_burn` now use the caller as the operator. ([#2134](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2134))
+ * `ERC777`: removed `_callsTokensToSend` and `_callTokensReceived`. ([#2134](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2134))
+ * `EnumerableSet`: renamed `get` to `at`. ([#2151](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2151))
+ * `ERC165Checker`: functions no longer have a leading underscore. ([#2150](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2150))
+ * `ERC721Metadata`, `ERC721Enumerable`: these contracts were removed, and their functionality merged into `ERC721`. ([#2160](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2160))
+ * `ERC721`: added a constructor for `name` and `symbol`. ([#2160](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2160))
+ * `ERC20Detailed`: this contract was removed and its functionality merged into `ERC20`. ([#2161](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2161))
+ * `ERC20`: added a constructor for `name` and `symbol`. `decimals` now defaults to 18. ([#2161](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2161))
+ * `Strings`: renamed `fromUint256` to `toString` ([#2188](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2188))
+
+## 2.5.1 (2020-04-24)
+
+### Bugfixes
+ * `ERC777`: fixed the `_send` and `_approve` internal functions not validating some of their arguments for non-zero addresses. ([#2212](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2212))
+
+## 2.5.0 (2020-02-04)
+
+### New features
+ * `SafeCast.toUintXX`: new library for integer downcasting, which allows for safe operation on smaller types (e.g. `uint32`) when combined with `SafeMath`. ([#1926](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1926))
+ * `ERC721Metadata`: added `baseURI`, which can be used for dramatic gas savings when all token URIs share a prefix (e.g. `http://api.myapp.com/tokens/<id>`). ([#1970](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1970))
+ * `EnumerableSet`: new library for storing enumerable sets of values. Only `AddressSet` is supported in this release. ([#2061](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/2061))
+ * `Create2`: simple library to make usage of the `CREATE2` opcode easier. ([#1744](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/1744))
+
+### Improvements
+ * `ERC777`: `_burn` is now internal, providing more flexibility and making it easier to create tokens that deflate. ([#1908](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/1908))
+ * `ReentrancyGuard`: greatly improved gas efficiency by using the net gas metering mechanism introduced in the Istanbul hardfork. ([#1992](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/1992), [#1996](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/1996))
+ * `ERC777`: improve extensibility by making `_send` and related functions `internal`. ([#2027](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2027))
+ * `ERC721`: improved revert reason when transferring tokens to a non-recipient contract. ([#2018](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2018))
+
+### Breaking changes
+ * `ERC165Checker` now requires a minimum Solidity compiler version of 0.5.10. ([#1829](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1829))
+
+## 2.4.0 (2019-10-29)
+
+### New features
+ * `Address.toPayable`: added a helper to convert between address types without having to resort to low-level casting. ([#1773](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1773))
+ * Facilities to make metatransaction-enabled contracts through the Gas Station Network. ([#1844](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/1844))
+ * `Address.sendValue`: added a replacement to Solidity's `transfer`, removing the fixed gas stipend. ([#1962](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1962))
+ * Added replacement for functions that don't forward all gas (which have been deprecated): ([#1976](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1976))
+   * `PullPayment.withdrawPaymentsWithGas(address payable payee)`
+   * `Escrow.withdrawWithGas(address payable payee)`
+ * `SafeMath`: added support for custom error messages to `sub`, `div` and `mod` functions. ([#1828](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/1828))
+
+### Improvements
+ * `Address.isContract`: switched from `extcodesize` to `extcodehash` for less gas usage. ([#1802](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1802))
+ * `ERC20` and `ERC777` updated to throw custom errors on subtraction overflows. ([#1828](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/1828))
+
+### Deprecations
+ * Deprecated functions that don't forward all gas: ([#1976](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1976))
+   * `PullPayment.withdrawPayments(address payable payee)`
+   * `Escrow.withdraw(address payable payee)`
+
+### Breaking changes
+ * `Address` now requires a minimum Solidity compiler version of 0.5.5. ([#1802](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1802))
+ * `SignatureBouncer` has been removed from drafts, both to avoid confusions with the GSN and `GSNRecipientSignature` (previously called `GSNBouncerSignature`) and because the API was not very clear. ([#1879](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/1879))
+
+### How to upgrade from 2.4.0-beta
+
+The final 2.4.0 release includes a refactor of the GSN contracts that will be a breaking change for 2.4.0-beta users.
+
+ * The default empty implementations of `_preRelayedCall` and `_postRelayedCall` were removed and must now be explicitly implemented always in custom recipients. If your custom recipient didn't include an implementation, you can provide an empty one.
+ * `GSNRecipient`, `GSNBouncerBase`, and `GSNContext` were all merged into `GSNRecipient`.
+ * `GSNBouncerSignature` and `GSNBouncerERC20Fee` were renamed to `GSNRecipientSignature` and `GSNRecipientERC20Fee`.
+ * It is no longer necessary to inherit from `GSNRecipient` when using `GSNRecipientSignature` and `GSNRecipientERC20Fee`.
+
+For example, a contract using `GSNBouncerSignature` would have to be changed in the following way.
+
+```diff
+-contract MyDapp is GSNRecipient, GSNBouncerSignature {
++contract MyDapp is GSNRecipientSignature {
+```
+
+Refer to the table below to adjust your inheritance list.
+
+| 2.4.0-beta                         | 2.4.0                        |
+| ---------------------------------- | ---------------------------- |
+| `GSNRecipient, GSNBouncerSignature`| `GSNRecipientSignature`      |
+| `GSNRecipient, GSNBouncerERC20Fee` | `GSNRecipientERC20Fee`       |
+| `GSNBouncerBase`                   | `GSNRecipient`               |
+
+## 2.3.0 (2019-05-27)
+
+### New features
+ * `ERC1820`: added support for interacting with the [ERC1820](https://eips.ethereum.org/EIPS/eip-1820) registry contract (`IERC1820Registry`), as well as base contracts that can be registered as implementers there. ([#1677](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1677))
+ * `ERC777`: support for the [ERC777 token](https://eips.ethereum.org/EIPS/eip-777), which has multiple improvements over `ERC20` (but is backwards compatible with it) such as built-in burning, a more  straightforward permission system, and optional sender and receiver hooks on transfer (mandatory for contracts!). ([#1684](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1684))
+ * All contracts now have revert reason strings, which give insight into error conditions, and help debug failing transactions. ([#1704](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1704))
+
+### Improvements
+ * Reverted the Solidity version bump done in v2.2.0, setting the minimum compiler version to v0.5.0, to prevent unexpected build breakage. Users are encouraged however to stay on top of new compiler releases, which usually include bugfixes. ([#1729](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1729))
+
+### Bugfixes
+ * `PostDeliveryCrowdsale`: some validations where skipped when paired with other crowdsale flavors, such as `AllowanceCrowdsale`, or `MintableCrowdsale` and `ERC20Capped`, which could cause buyers to not be able to claim their purchased tokens. ([#1721](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1721))
+ * `ERC20._transfer`: the `from` argument was allowed to be the zero address, so it was possible to internally trigger a transfer of 0 tokens from the zero address. This address is not a valid destinatary of transfers, nor can it give or receive allowance, so this behavior was inconsistent. It now reverts. ([#1752](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1752))
+
+## 2.2.0 (2019-03-14)
+
+### New features
+ * `ERC20Snapshot`: create snapshots on demand of the token balances and total supply, to later retrieve and e.g. calculate dividends at a past time. ([#1617](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1617))
+ * `SafeERC20`: `ERC20` contracts with no return value (i.e. that revert on failure) are now supported. ([#1655](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1655))
+ * `ERC20`: added internal `_approve(address owner, address spender, uint256 value)`, allowing derived contracts to set the allowance of arbitrary accounts. ([#1609](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1609))
+ * `ERC20Metadata`: added internal `_setTokenURI(string memory tokenURI)`. ([#1618](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1618))
+ * `TimedCrowdsale`: added internal `_extendTime(uint256 newClosingTime)` as well as `TimedCrowdsaleExtended(uint256 prevClosingTime, uint256 newClosingTime)` event allowing to extend the crowdsale, as long as it hasn't already closed.
+
+### Improvements
+ * Upgraded the minimum compiler version to v0.5.2: this removes many Solidity warnings that were false positives. ([#1606](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1606))
+ * `ECDSA`: `recover` no longer accepts malleable signatures (those using upper-range values for `s`, or 0/1 for `v`). ([#1622](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1622))
+ * ``ERC721``'s transfers are now more gas efficient due to removal of unnecessary `SafeMath` calls. ([#1610](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1610))
+ * Fixed variable shadowing issues. ([#1606](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1606))
+
+### Bugfixes
+ * (minor) `SafeERC20`: `safeApprove` wasn't properly checking for a zero allowance when attempting to set a non-zero allowance. ([#1647](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1647))
+
+### Breaking changes in drafts
+ * `TokenMetadata` has been renamed to `ERC20Metadata`. ([#1618](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1618))
+ * The library `Counter` has been renamed to `Counters` and its API has been improved. See an example in `ERC721`, lines [17](https://github.com/OpenZeppelin/openzeppelin-solidity/blob/3cb4a00fce1da76196ac0ac3a0ae9702b99642b5/contracts/token/ERC721/ERC721.sol#L17) and [204](https://github.com/OpenZeppelin/openzeppelin-solidity/blob/3cb4a00fce1da76196ac0ac3a0ae9702b99642b5/contracts/token/ERC721/ERC721.sol#L204). ([#1610](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1610))
+
+## 2.1.3 (2019-02-26)
+ * Backported `SafeERC20.safeApprove` bugfix. ([#1647](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1647))
+
+## 2.1.2 (2019-01-17)
+ * Removed most of the test suite from the npm package, except `PublicRole.behavior.js`, which may be useful to users testing their own `Roles`.
+
+## 2.1.1 (2019-01-04)
+ * Version bump to avoid conflict in the npm registry.
+
+## 2.1.0 (2019-01-04)
+
+### New features
+ * Now targeting the 0.5.x line of Solidity compilers. For 0.4.24 support, use version 2.0 of OpenZeppelin.
+ * `WhitelistCrowdsale`: a crowdsale where only whitelisted accounts (`WhitelistedRole`) can purchase tokens. Adding or removing accounts from the whitelist is done by whitelist admins (`WhitelistAdminRole`). Similar to the pre-2.0 `WhitelistedCrowdsale`. ([#1525](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1525), [#1589](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1589))
+ * `RefundablePostDeliveryCrowdsale`: replacement for `RefundableCrowdsale` (deprecated, see below) where tokens are only granted once the crowdsale ends (if it meets its goal). ([#1543](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1543))
+ * `PausableCrowdsale`: allows for pausers (`PauserRole`) to pause token purchases. Other crowdsale operations (e.g. withdrawals and refunds, if applicable) are not affected. ([#832](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/832))
+ * `ERC20`: `transferFrom` and `_burnFrom ` now emit `Approval` events, to represent the token's state comprehensively through events. ([#1524](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1524))
+ * `ERC721`: added `_burn(uint256 tokenId)`, replacing the similar deprecated function (see below). ([#1550](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1550))
+ * `ERC721`: added `_tokensOfOwner(address owner)`, allowing to internally retrieve the array of an account's owned tokens. ([#1522](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1522))
+ * Crowdsales: all constructors are now `public`, meaning it is not necessary to extend these contracts in order to deploy them. The exception is `FinalizableCrowdsale`, since it is meaningless unless extended. ([#1564](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1564))
+ * `SignedSafeMath`: added overflow-safe operations for signed integers (`int256`). ([#1559](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1559), [#1588](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1588))
+
+### Improvements
+ * The compiler version required by `Array` was behind the rest of the libray so it was updated to `v0.4.24`. ([#1553](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1553))
+ * Now conforming to a 4-space indentation code style. ([1508](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1508))
+ * `ERC20`: more gas efficient due to removed redundant `require`s. ([#1409](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1409))
+ * `ERC721`: fixed a bug that prevented internal data structures from being properly cleaned, missing potential gas refunds. ([#1539](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1539) and [#1549](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1549))
+ * `ERC721`: general gas savings on `transferFrom`, `_mint` and `_burn`, due to redudant `require`s and `SSTORE`s. ([#1549](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1549))
+
+### Bugfixes
+
+### Breaking changes
+
+### Deprecations
+ * `ERC721._burn(address owner, uint256 tokenId)`: due to the `owner` parameter being unnecessary. ([#1550](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1550))
+ * `RefundableCrowdsale`: due to trading abuse potential on crowdsales that miss their goal. ([#1543](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1543))

CODE_OF_CONDUCT.md

@@ -0,0 +1,73 @@
+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+In the interest of fostering an open and welcoming environment, we as
+contributors and maintainers pledge to making participation in our project and
+our community a harassment-free experience for everyone, regardless of age, body
+size, disability, ethnicity, sex characteristics, gender identity and expression,
+level of experience, education, socio-economic status, nationality, personal
+appearance, race, religion, or sexual identity and orientation.
+
+## Our Standards
+
+Examples of behavior that contributes to creating a positive environment
+include:
+
+* Using welcoming and inclusive language
+* Being respectful of differing viewpoints and experiences
+* Gracefully accepting constructive criticism
+* Focusing on what is best for the community
+* Showing empathy towards other community members
+
+Examples of unacceptable behavior by participants include:
+
+* The use of sexualized language or imagery and unwelcome sexual attention or
+  advances
+* Trolling, insulting/derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or electronic
+  address, without explicit permission
+* Other conduct which could reasonably be considered inappropriate in a
+  professional setting
+
+## Our Responsibilities
+
+Project maintainers are responsible for clarifying the standards of acceptable
+behavior and are expected to take appropriate and fair corrective action in
+response to any instances of unacceptable behavior.
+
+Project maintainers have the right and responsibility to remove, edit, or
+reject comments, commits, code, wiki edits, issues, and other contributions
+that are not aligned to this Code of Conduct, or to ban temporarily or
+permanently any contributor for other behaviors that they deem inappropriate,
+threatening, offensive, or harmful.
+
+## Scope
+
+This Code of Conduct applies both within project spaces and in public spaces
+when an individual is representing the project or its community. Examples of
+representing a project or community include using an official project e-mail
+address, posting via an official social media account, or acting as an appointed
+representative at an online or offline event. Representation of a project may be
+further defined and clarified by project maintainers.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported by contacting the project team at maintainers@openzeppelin.org. All
+complaints will be reviewed and investigated and will result in a response that
+is deemed necessary and appropriate to the circumstances. The project team is
+obligated to maintain confidentiality with regard to the reporter of an incident.
+Further details of specific enforcement policies may be posted separately.
+
+Project maintainers who do not follow or enforce the Code of Conduct in good
+faith may face temporary or permanent repercussions as determined by other
+members of the project's leadership.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4,
+available at https://www.contributor-covenant.org/version/1/4/code-of-conduct.html
+
+[homepage]: https://www.contributor-covenant.org

CONTRIBUTING.md

@@ -0,0 +1,64 @@
+Contributing to OpenZeppelin Contracts
+=======
+
+We really appreciate and value contributions to OpenZeppelin Contracts. Please take 5' to review the items listed below to make sure that your contributions are merged as soon as possible.
+
+## Contribution guidelines
+
+Smart contracts manage value and are highly vulnerable to errors and attacks. We have very strict [guidelines], please make sure to review them!
+
+## Creating Pull Requests (PRs)
+
+As a contributor, you are expected to fork this repository, work on your own fork and then submit pull requests. The pull requests will be reviewed and eventually merged into the main repo. See ["Fork-a-Repo"](https://help.github.com/articles/fork-a-repo/) for how this works.
+
+## A typical workflow
+
+1) Make sure your fork is up to date with the main repository:
+
+```
+cd openzeppelin-contracts
+git remote add upstream https://github.com/OpenZeppelin/openzeppelin-contracts.git
+git fetch upstream
+git pull --rebase upstream master
+```
+NOTE: The directory `openzeppelin-contracts` represents your fork's local copy.
+
+2) Branch out from `master` into `fix/some-bug-#123`:
+(Postfixing #123 will associate your PR with the issue #123 and make everyone's life easier =D)
+```
+git checkout -b fix/some-bug-#123
+```
+
+3) Make your changes, add your files, commit, and push to your fork.
+
+```
+git add SomeFile.js
+git commit "Fix some bug #123"
+git push origin fix/some-bug-#123
+```
+
+4) Run tests, linter, etc. This can be done by running local continuous integration and make sure it passes.
+
+```bash
+npm test
+npm run lint
+```
+
+5) Go to [github.com/OpenZeppelin/openzeppelin-contracts](https://github.com/OpenZeppelin/openzeppelin-contracts) in your web browser and issue a new pull request.
+
+*IMPORTANT* Read the PR template very carefully and make sure to follow all the instructions. These instructions
+refer to some very important conditions that your PR must meet in order to be accepted, such as making sure that all tests pass, JS linting tests pass, Solidity linting tests pass, etc.
+
+6) Maintainers will review your code and possibly ask for changes before your code is pulled in to the main repository. We'll check that all tests pass, review the coding style, and check for general code correctness. If everything is OK, we'll merge your pull request and your code will be part of OpenZeppelin Contracts.
+
+*IMPORTANT* Please pay attention to the maintainer's feedback, since its a necessary step to keep up with the standards OpenZeppelin Contracts attains to.
+
+## All set!
+
+If you have any questions, feel free to post them to github.com/OpenZeppelin/openzeppelin-contracts/issues.
+
+Finally, if you're looking to collaborate and want to find easy tasks to start, look at the issues we marked as ["Good first issue"](https://github.com/OpenZeppelin/openzeppelin-contracts/labels/good%20first%20issue).
+
+Thanks for your time and code!
+
+[guidelines]: GUIDELINES.md

DOCUMENTATION.md

@@ -0,0 +1,16 @@
+Documentation is hosted at https://docs.openzeppelin.com/contracts.
+
+All of the content for the site is in this repository. The guides are in the
+[docs](/docs) directory, and the API Reference is extracted from comments in
+the source code. If you want to help improve the content, this is the
+repository you should be contributing to.
+
+[`solidity-docgen`](https://github.com/OpenZeppelin/solidity-docgen) is the
+program that extracts the API Reference from source code.
+
+The [`docs.openzeppelin.com`](https://github.com/OpenZeppelin/docs.openzeppelin.com)
+repository hosts the configuration for the entire site, which includes
+documentation for all of the OpenZeppelin projects.
+
+To run the docs locally you should run `npm run docs:watch` on this
+repository.

GUIDELINES.md

@@ -0,0 +1,105 @@
+Design Guidelines
+=======
+
+These are some global design goals in OpenZeppelin Contracts.
+
+#### D0 - Security in Depth
+We strive to provide secure, tested, audited code. To achieve this, we need to match intention with function. Thus, documentation, code clarity, community review and security discussions are fundamental.
+
+#### D1 - Simple and Modular
+Simpler code means easier audits, and better understanding of what each component does. We look for small files, small contracts, and small functions. If you can separate a contract into two independent functionalities you should probably do it.
+
+#### D2 - Naming Matters
+
+We take our time with picking names. Code is going to be written once, and read hundreds of times. Renaming for clarity is encouraged.
+
+#### D3 - Tests
+
+Write tests for all your code. We encourage Test Driven Development so we know when our code is right. Even though not all code in the repository is tested at the moment, we aim to test every line of code in the future.
+
+#### D4 - Check preconditions and post-conditions
+
+A very important way to prevent vulnerabilities is to catch a contract’s inconsistent state as early as possible. This is why we want functions to check pre- and post-conditions for executing its logic. When writing code, ask yourself what you are expecting to be true before and after the function runs, and express it in code.
+
+#### D5 - Code Consistency
+
+Consistency on the way classes are used is paramount to an easier understanding of the library. The codebase should be as unified as possible. Read existing code and get inspired before you write your own. Follow the style guidelines. Don’t hesitate to ask for help on how to best write a specific piece of code.
+
+#### D6 - Regular Audits
+Following good programming practices is a way to reduce the risk of vulnerabilities, but professional code audits are still needed. We will perform regular code audits on major releases, and hire security professionals to provide independent review.
+
+# Style Guidelines
+
+The design guidelines have quite a high abstraction level. These style guidelines are more concrete and easier to apply, and also more opinionated. We value clean code and consistency, and those are prerequisites for us to include new code in the repository. Before proposing a change, please read these guidelines and take some time to familiarize yourself with the style of the existing codebase.
+
+## Solidity code
+
+In order to be consistent with all the other Solidity projects, we follow the
+[official recommendations documented in the Solidity style guide](http://solidity.readthedocs.io/en/latest/style-guide.html).
+
+Any exception or additions specific to our project are documented below.
+
+* Try to avoid acronyms and abbreviations.
+
+* All state variables should be private.
+
+* Private state variables should have an underscore prefix.
+
+    ```
+    contract TestContract {
+      uint256 private _privateVar;
+      uint256 internal _internalVar;
+    }
+    ```
+
+* Parameters must not be prefixed with an underscore.
+
+    ```
+    function test(uint256 testParameter1, uint256 testParameter2) {
+    ...
+    }
+    ```
+
+* Internal and private functions should have an underscore prefix.
+
+    ```
+    function _testInternal() internal {
+      ...
+    }
+    ```
+
+    ```
+    function _testPrivate() private {
+      ...
+    }
+    ```
+
+* Events should be emitted immediately after the state change that they
+  represent, and consequently they should be named in past tense.
+
+    ```
+    function _burn(address who, uint256 value) internal {
+      super._burn(who, value);
+      emit TokensBurned(who, value);
+    }
+    ```
+
+  Some standards (e.g. ERC20) use present tense, and in those cases the
+  standard specification prevails.
+  
+* Interface names should have a capital I prefix.
+
+    ```
+    interface IERC777 {
+    ```
+
+
+## Tests
+
+* Tests Must be Written Elegantly
+
+    Tests are a good way to show how to use the library, and maintaining them is extremely necessary. Don't write long tests, write helper functions to make them be as short and concise as possible (they should take just a few lines each), and use good variable names.
+
+* Tests Must not be Random
+
+    Inputs for tests should not be generated randomly. Accounts used to create test contracts are an exception, those can be random. Also, the type and structure of outputs should be checked.

LICENSE

@@ -0,0 +1,22 @@
+The MIT License (MIT)
+
+Copyright (c) 2016-2020 zOS Global Limited
+
+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 all 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.

README.md

@@ -0,0 +1,96 @@
+# <img src="icon.svg" alt="OpenZeppelin" height="40px" align="left"> OpenZeppelin Contracts Upgradeable
+
+[![Docs](https://img.shields.io/badge/docs-%F0%9F%93%84-blue)](https://docs.openzeppelin.com/contracts/upgradeable)
+[![NPM Package](https://img.shields.io/npm/v/@openzeppelin/contracts-upgradeable.svg)](https://www.npmjs.org/package/@openzeppelin/contracts-upgradeable)
+
+This repository hosts the Upgradeable variant of [OpenZeppelin Contracts], meant for use in upgradeable contracts. This variant is available as separate package called `@openzeppelin/contracts-upgradeable`.
+
+[OpenZeppelin Contracts]: https://github.com/OpenZeppelin/openzeppelin-contracts
+
+It follows all of the rules for [Writing Upgradeable Contracts]: constructors are replaced by initializer functions, state variables are initialized in initializer functions, and we additionally check for storage incompatibilities across minor versions.
+
+[Writing Upgradeable Contracts]: https://docs.openzeppelin.com/upgrades-plugins/writing-upgradeable
+
+> :warning: **Warning**
+>
+> There will be storage incompatibilities across major versions of this package, which makes it unsafe to upgrade a deployed contract from one major version to another, for example from 3.4.0 to 4.0.0.
+> 
+> Similarly, it is not safe to upgrade from `@openzeppelin/contracts-ethereum-package` (a similar previous package) to `@openzeppelin/contracts-upgradeable`.
+>
+> **It is strongly encouraged to use these contracts together with a tool that can automatically guarantee the safety of an upgradeable contract, such as the [OpenZeppelin Upgrades Plugins](https://github.com/OpenZeppelin/openzeppelin-upgrades).**
+
+## Overview
+
+### Installation
+
+```console
+$ npm install @openzeppelin/contracts-upgradeable
+```
+
+### Usage
+
+The package replicates the structure of the main OpenZeppelin Contracts package, but every file and contract has the suffix `Upgradeable`.
+
+```diff
+-import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
++import "@openzeppelin/contracts-upgradeable/token/ERC721/ERC721Upgradeable.sol";
+ 
+-contract MyCollectible is ERC721 {
++contract MyCollectible is ERC721Upgradeable {
+```
+
+Constructors are replaced by internal initializer functions following the naming convention `__{ContractName}_init`. Since these are internal, you must always define your own public initializer function and call the parent initializer of the contract you extend.
+
+```diff
+-    constructor() ERC721("MyCollectible", "MCO") {
++    function initialize() initializer public {
++        __ERC721_init("MyCollectible", "MCO");
+     }
+```
+
+> **Caution**
+>
+> Use with multiple inheritance requires special care. Initializer functions are not linearized by the compiler like constructors. Because of this, each `__{ContractName}_init` function embeds the linearized calls to all parent initializers. As a consequence, calling two of these `init` functions can potentially initialize the same contract twice.
+>
+> The function `__{ContractName}_init_unchained` found in every contract is the initializer function minus the calls to parent initializers, and can be used to avoid the double initialization problem, but doing this manually is not recommended. We hope to be able to implement safety checks for this in future versions of the Upgrades Plugins.
+
+_If you're new to smart contract development, head to [Developing Smart Contracts](https://docs.openzeppelin.com/learn/developing-smart-contracts) to learn about creating a new project and compiling your contracts._
+
+To keep your system secure, you should **always** use the installed code as-is, and neither copy-paste it from online sources, nor modify it yourself. The library is designed so that only the contracts and functions you use are deployed, so you don't need to worry about it needlessly increasing gas costs.
+
+## Learn More
+
+The guides in the [docs site](https://docs.openzeppelin.com/contracts) will teach about different concepts, and how to use the related contracts that OpenZeppelin Contracts provides:
+
+* [Access Control](https://docs.openzeppelin.com/contracts/access-control): decide who can perform each of the actions on your system.
+* [Tokens](https://docs.openzeppelin.com/contracts/tokens): create tradeable assets or collectives, and distribute them via [Crowdsales](https://docs.openzeppelin.com/contracts/crowdsales).
+* [Gas Station Network](https://docs.openzeppelin.com/contracts/gsn): let your users interact with your contracts without having to pay for gas themselves.
+* [Utilities](https://docs.openzeppelin.com/contracts/utilities): generic useful tools, including non-overflowing math, signature verification, and trustless paying systems.
+
+The [full API](https://docs.openzeppelin.com/contracts/api/token/ERC20) is also thoroughly documented, and serves as a great reference when developing your smart contract application. You can also ask for help or follow Contracts's development in the [community forum](https://forum.openzeppelin.com).
+
+Finally, you may want to take a look at the [guides on our blog](https://blog.openzeppelin.com/guides), which cover several common use cases and good practices.. The following articles provide great background reading, though please note, some of the referenced tools have changed as the tooling in the ecosystem continues to rapidly evolve.
+
+* [The Hitchhiker’s Guide to Smart Contracts in Ethereum](https://blog.openzeppelin.com/the-hitchhikers-guide-to-smart-contracts-in-ethereum-848f08001f05) will help you get an overview of the various tools available for smart contract development, and help you set up your environment.
+* [A Gentle Introduction to Ethereum Programming, Part 1](https://blog.openzeppelin.com/a-gentle-introduction-to-ethereum-programming-part-1-783cc7796094) provides very useful information on an introductory level, including many basic concepts from the Ethereum platform.
+* For a more in-depth dive, you may read the guide [Designing the Architecture for Your Ethereum Application](https://blog.openzeppelin.com/designing-the-architecture-for-your-ethereum-application-9cec086f8317), which discusses how to better structure your application and its relationship to the real world.
+
+## Security
+
+This project is maintained by [OpenZeppelin](https://openzeppelin.com), and developed following our high standards for code quality and security. OpenZeppelin Contracts is meant to provide tested and community-audited code, but please use common sense when doing anything that deals with real money! We take no responsibility for your implementation decisions and any security problems you might experience.
+
+The core development principles and strategies that OpenZeppelin Contracts is based on include: security in depth, simple and modular code, clarity-driven naming conventions, comprehensive unit testing, pre-and-post-condition sanity checks, code consistency, and regular audits.
+
+The latest audit was done on October 2018 on version 2.0.0.
+
+We have a [**bug bounty program** on Immunefi](https://www.immunefi.com/bounty/openzeppelin). Please report any security issues you find through the Immunefi dashboard, or reach out to security@openzeppelin.com.
+
+Critical bug fixes will be backported to past major releases.
+
+## Contribute
+
+OpenZeppelin Contracts exists thanks to its contributors. There are many ways you can participate and help build high quality software. Check out the [contribution guide](CONTRIBUTING.md)!
+
+## License
+
+OpenZeppelin Contracts is released under the [MIT License](LICENSE).

RELEASING.md

@@ -0,0 +1,36 @@
+# Releasing
+
+> Visit the documentation for [details about release schedule].
+
+Start on an up-to-date `master` branch.
+
+Create the release branch with `npm run release start minor`.
+
+Publish a release candidate with `npm run release rc`.
+
+Publish the final release with `npm run release final`.
+
+Follow the general [OpenZeppelin Contracts release checklist].
+
+[details about release schedule]: https://docs.openzeppelin.com/contracts/releases-stability
+[OpenZeppelin Contracts release checklist]: https://github.com/OpenZeppelin/code-style/blob/master/RELEASE_CHECKLIST.md
+
+
+## Merging the release branch
+
+After the final release, the release branch should be merged back into `master`. This merge must not be squashed because it would lose the tagged release commit. Since the GitHub repo is set up to only allow squashed merges, the merge should be done locally and pushed.
+
+Make sure to have the latest changes from `upstream` in your local release branch.
+
+```
+git checkout release-vX.Y.Z
+git pull upstream
+```
+
+```
+git checkout master
+git merge --no-ff release-vX.Y.Z
+git push upstream master
+```
+
+The release branch can then be deleted on GitHub.

SECURITY.md

@@ -0,0 +1,20 @@
+# Security Policy
+
+## Bug Bounty
+
+We have a [**bug bounty program** on Immunefi](https://www.immunefi.com/bounty/openzeppelin). Please report any security issues you find through the Immunefi dashboard, or reach out to security@openzeppelin.com.
+
+Critical bug fixes will be backported to past major releases.
+
+## Supported Versions
+
+The recommendation is to use the latest version available.
+
+| Version | Supported                            |
+| ------- | ------------------------------------ |
+| 4.x     | :white_check_mark::white_check_mark: |
+| 3.4     | :white_check_mark:                   |
+| 2.5     | :white_check_mark:                   |
+| < 2.0   | :x:                                  |
+
+Note that the Solidity language itself only guarantees security updates for the latest release.

UPGRADEABLE.md

@@ -0,0 +1,47 @@
+# Technical notes about the Upgradeable repository
+
+## [Branches](https://github.com/OpenZeppelin/openzeppelin-contracts-upgradeable/branches)
+
+### `patches`
+
+Built on top of the `master` branch of the vanilla Contracts repo, contains the changes necessary to build this package: it adds the scripts to transpile and GitHub Actions for it to work automatically, changes the package name, etc.
+
+It can also include small changes to the Solidity code, such as reordering of state variables, in order to ensure storage compatibility.
+
+It's an important goal that this branch should be easy to merge with the vanilla Contracts repo, avoiding merge conflicts as much as possible. This is necessary to reduce manual intervention and ensure automation runs smoothly.
+
+This branch will not necessarily be up to date with the vanilla `master` branch, only up to the point necessary to guarantee successful merging with any new updates. In some cases it will be necessary to apply a manual merge with new changes, it is this branch that should be updated for the changes to propagate to all other branches.
+
+### `patched/master`, `patched/release-vX.Y`
+
+These branches are the merge between `patches` and the corresponding branch from vanilla Contracts. These branches should generally not be updated manually.
+
+### `master`, `release-vX.Y`
+
+Contains the transpiled code corresponding to the branch from vanilla Contracts of the same name. These are generated automatically based on their `patched/*` branch. These branches should never be manually updated, because they will be overwritten automatically with the transpiled version of `patched/*`. Instead, changes should be made in `patches`.
+
+## [Actions Workflows](https://github.com/OpenZeppelin/openzeppelin-contracts-upgradeable/actions)
+
+### [Merge upstream](/.github/workflows/merge-upstream.yml)
+
+All this does is fetch the latest changes from a corresponding branch in the vanilla Contracts repo, tries to merge them with `patches`, and then pushes the updated branch to `patched/*`. If the merge has conflicts, the worfklow will fail. We should be notified of this so that we can updated the `patches` branch resolving conflicts and trigger the merge again. This should not happen often.
+
+### [Transpile](/.github/workflows/transpile.yml)
+
+Runs every time a `patched/*` branch is pushed to (for example as part of the Merge upstream workflow), transpiles the contents of that branch, and pushes the results as a new commit on the transpiled branch.
+
+### [Test](/.github/workflows/test.yml)
+
+Runs normal Contracts tests on the `master` and `release-v*` branches.
+
+## Scripts
+
+### `transpile-onto.sh`
+
+```
+bash scripts/upgradeable/transpile-onto.sh <target> [base]
+```
+
+Transpiles the contents of the current git branch and commits the result as a new commit on branch `<target>`. If branch `<target>` doesn't exist, it will copy the commit history of `[base]` (this is used in GitHub Actions, but is usually not necessary locally).
+
+This script can be used manually to build transpiled versions of specific commits, or branches other than the `master` Contracts branch.

audit/2017-03.md

@@ -0,0 +1,292 @@
+# OpenZeppelin Audit
+
+NOTE ON 2021-07-19: This report makes reference to Zeppelin, OpenZeppelin, OpenZeppelin [C]ontracts, the OpenZeppelin team, and OpenZeppelin library. Many of these things have since been renamed and know that this audit applies to what is currently called the OpenZeppelin Contracts which are maintained by the OpenZeppelin Conracts Community.
+
+March, 2017
+Authored by Dennis Peterson and Peter Vessenes
+
+# Introduction
+
+Zeppelin requested that New Alchemy perform an audit of the contracts in their OpenZeppelin library. The OpenZeppelin contracts are a set of contracts intended to be a safe building block for a variety of uses by parties that may not be as sophisticated as the OpenZeppelin team. It is a design goal that the contracts be deployable safely and "as-is".
+
+The contracts are hosted at:
+
+https://github.com/OpenZeppelin/zeppelin-solidity
+
+All the contracts in the "contracts" folder are in scope.
+
+The git commit hash we evaluated is:
+9c5975a706b076b7000e8179f8101e0c61024c87
+
+# Disclaimer
+
+The audit makes no statements or warrantees about utility of the code, safety of the code, suitability of the business model, regulatory regime for the business model, or any other statements about fitness of the contracts to purpose, or their bugfree status. The audit documentation is for discussion purposes only.
+
+# Executive Summary
+
+Overall the OpenZeppelin codebase is of reasonably high quality -- it is clean, modular and follows best practices throughout.
+
+It is still in flux as a codebase, and needs better documentation per file as to expected behavior and future plans. It probably needs more comprehensive and aggressive tests written by people less nice than the current OpenZeppelin team.
+
+We identified two critical errors and one moderate issue, and would not recommend this commit hash for public use until these bugs are remedied.
+
+The repository includes a set of Truffle unit tests, a requirement and best practice for smart contracts like these; we recommend these be bulked up.
+
+# Discussion
+
+## Big Picture: Is This A Worthwhile Project?
+
+As soon as a developer touches OpenZeppelin contracts, they will modify something, leaving them in an un-audited state. We do not recommend developers deploy any unaudited code to the Blockchain if it will handle money, information or other things of value.
+
+> "In accordance with Unix philosophy, Perl gives you enough rope to hang yourself"
+> --Larry Wall
+
+We think this is an incredibly worthwhile project -- aided by the high code quality. Creating a framework that can be easily extended helps increase the average code quality on the Blockchain by charting a course for developers and encouraging containment of modifications to certain sections.
+
+> "Rust: The language that makes you take the safety off before shooting yourself in the foot"
+> -- (@mbrubeck)
+
+We think much more could be done here, and recommend the OpenZeppelin team keep at this and keep focusing on the design goal of removing rope and adding safety.
+
+## Solidity Version Updates Recommended
+
+Most of the code uses Solidity 0.4.11, but some files under `Ownership` are marked 0.4.0. These should be updated.
+
+Solidity 0.4.10 will add several features which could be useful in these contracts:
+
+- `assert(condition)`, which throws if the condition is false
+
+- `revert()`, which rolls back without consuming all remaining gas.
+
+- `address.transfer(value)`, which is like `send` but automatically propagates exceptions, and supports `.gas()`. See https://github.com/ethereum/solidity/issues/610 for more on this.
+
+## Error Handling: Throw vs Return False
+Solidity standards allow two ways to handle an error -- either calling `throw` or returning `false`. Both have benefits. In particular, a `throw` guarantees a complete wipe of the call stack (up to the preceding external call), whereas `false` allows a function to continue.
+
+In general we prefer `throw` in our code audits, because it is simpler -- it's less for an engineer to keep track of. Returning `false` and using logic to check results can quickly become a poorly-tracked state machine, and this sort of complexity can cause errors.
+
+In the OpenZeppelin contracts, both styles are used in different parts of the codebase. `SimpleToken` transfers throw upon failure, while the full ERC20 token returns `false`. Some modifiers `throw`, others just wrap the function body in a conditional, effectively allowing the function to return false if the condition is not met.
+
+We don't love this, and would usually recommend you stick with one style or the other throughout the codebase.
+
+In at least one case, these different techniques are combined cleverly (see the Multisig comments, line 65). As a set of contracts intended for general use, we recommend you either strive for more consistency or document explicit design criteria that govern which techniques are used where.
+
+Note that it may be impossible to use either one in all situations. For example, SafeMath functions pretty much have to throw upon failure, but ERC20 specifies returning booleans. Therefore we make no particular recommendations, but simply point out inconsistencies to consider.
+
+# Critical Issues
+
+## Stuck Ether in Crowdsale contract
+CrowdsaleToken.sol has no provision for withdrawing the raised ether. We *strongly* recommend a standard `withdraw` function be added. There is no scenario in which someone should deploy this contract as is, whether for testing or live.
+
+## Recursive Call in MultisigWallet
+Line 45 of `MultisigWallet.sol` checks if the amount being sent by `execute` is under a daily limit.
+
+This function can only be called by the "Owner". As a first angle of attack, it's worth asking what will happen if the multisig wallet owners reset the daily limit by approving a call to `resetSpentToday`.
+
+If a chain of calls can be constructed in which the owner confirms the `resetSpentToday` function and then withdraws through `execute` in a recursive call, the contract can be drained. In fact, this could be done without a recursive call, just through repeated `execute` calls alternating with the `confirm` calls.
+
+We are still working through the confirmation protocol in `Shareable.sol`, but we are not convinced that this is impossible, in fact it looks possible. The flexibility any shared owner has in being able to revoke confirmation later is another worrisome angle of approach even if some simple patches are included.
+
+This bug has a number of causes that need to be addressed:
+
+1. `resetSpentToday` and `confirm` together do not limit the days on which the function can be called or (it appears) the number of times it can be called.
+1. Once a call has been confirmed and `execute`d it appears that it can be re-executed. This is not good.
+3. `confirmandCheck` doesn't seem to have logic about whether or not the function in question has been called.
+4. Even if it did, `revoke` would need updates and logic to deal with revocation requests after a function call had been completed.
+
+We do not recommend using the MultisigWallet until these issues are fixed.
+
+# Moderate to Minor Issues
+
+## PullPayment
+PullPayment.sol needs some work. It has no explicit provision for cancelling a payment. This would be desirable in a number of scenarios; consider a payee losing their wallet, or giving a griefing address, or just an address that requires more than the default gas offered by `send`.
+
+`asyncSend` has no overflow checking. This is a bad plan. We recommend overflow and underflow checking at the layer closest to the data manipulation.
+
+`asyncSend` allows more balance to be queued up for sending than the contract holds. This is probably a bad idea, or at the very least should be called something different. If the intent is to allow this, it should have provisions for dealing with race conditions between competing `withdrawPayments` calls.
+
+It would be nice to see how many payments are pending. This would imply a bit of a rewrite; we recommend this contract get some design time, and that developers don't rely on it in its current state.
+
+## Shareable Contract
+
+We do not believe the `Shareable.sol` contract is ready for primetime. It is missing functions, and as written may be vulnerable to a reordering attack -- an attack in which a miner or other party "racing" with a smart contract participant inserts their own information into a list or mapping.
+
+The confirmation and revocation code needs to be looked over with a very careful eye imagining extraordinarily bad behavior by shared owners before this contract can be called safe.
+
+No sanity checks on the initial constructor's `required` argument are worrisome as well.
+
+# Line by Line Comments
+
+## Lifecycle
+
+### Killable
+
+Very simple, allows owner to call selfdestruct, sending funds to owner. No issues. However, note that `selfdestruct` should typically not be used; it is common that a developer may want to access data in a former contract, and they may not understand that `selfdestruct` limits access to the contract. We recommend better documentation about this dynamic, and an alternate function name for `kill` like `completelyDestroy` while `kill` would perhaps merely send funds to the owner.
+
+Also note that a killable function allows the owner to take funds regardless of other logic. This may be desirable or undesirable depending on the circumstances. Perhaps `Killable` should have a different name as well.
+
+### Migrations
+
+I presume that the goal of this contract is to allow and annotate a migration to a new smart contract address. We are not clear here how this would be accomplished by the code; we'd like to review with the OpenZeppelin team.
+
+### Pausable
+
+We like these pauses! Note that these allow significant griefing potential by owners, and that this might not be obvious to participants in smart contracts using the OpenZeppelin framework. We would recommend that additional sample logic be added to for instance the TokenContract showing safer use of the pause and resume functions. In particular, we would recommend a timelock after which anyone could unpause the contract.
+
+The modifers use the pattern `if(bool){_;}`. This is fine for functions that return false upon failure, but could be problematic for functions expected to throw upon failure. See our comments above on standardizing on `throw` or `return(false)`.
+
+## Ownership
+
+### Ownable
+
+Line 19: Modifier throws if doesn't meet condition, in contrast to some other inheritable modifiers (e.g. in Pausable) that use `if(bool){_;}`.
+
+### Claimable
+
+Inherits from Ownable but the existing owner sets a pendingOwner who has to claim ownership.
+
+Line 17: Another modifier that throws.
+
+### DelayedClaimable
+
+Is there any reason to descend from Ownable directly, instead of just Claimable, which descends from Ownable? If not, descending from both just adds confusion.
+
+### Contactable
+
+Allows owner to set a public string of contract information. No issues.
+
+### Shareable
+
+This needs some work. Doesn't check if `_required <= len(_owners)` for instance, that would be a bummer. What if _required were like `MAX - 1`?
+
+I have a general concern about the difference between `owners`, `_owners`, and `owner` in `Ownable.sol`. I recommend "Owners" be renamed. In general we do not recomment single character differences in variable names, although a preceding underscore is not uncommon in Solidity code.
+
+Line 34: "this contract only has six types of events"...actually only two.
+
+Line 61: Why is `ownerIndex` keyed by addresses hashed to `uint`s? Why not use the addresses directly, so `ownerIndex` is less obscure, and so there's stronger typing?
+
+Line 62: Do not love `++i) ... owners[2+ i]`. Makes me do math, which is not what I want to do. I want to not have to do math.
+
+There should probably be a function for adding a new operation, so the developer doesn't have to work directly with the internal data. (This would make the multisig contract even shorter.)
+
+There's a `revoke` function but not a `propose` function that we can see.
+
+Beware reordering. If `propose` allows the user to choose a bytes string for their proposal, bad things(TM) will happen as currently written.
+
+
+### Multisig
+
+Just an interface. Note it allows changing an owner address, but not changing the number of owners. This is somewhat limiting but also simplifies implementation.
+
+## Payment
+
+### PullPayment
+
+Safe from reentrance attack since ether send is at the end, plus it uses `.send()` rather than `.call.value()`.
+
+There's an argument to be made that `.call.value()` is a better option *if* you're sure that it will be done after all state updates, since `.send` will fail if the recipient has an expensive fallback function. However, in the context of a function meant to be embedded in other contracts, it's probably better to use `.send`. One possible compromise is to add a function which allows only the owner to send ether via `.call.value`.
+
+If you don't use `call.value` you should implement a `cancel` function in case some value is pending here.
+
+Line 14:
+Doesn't use safeAdd. Although it appears that payout amounts can only be increased, in fact the payer could lower the payout as much as desired via overflow. Also, the payer could add a large non-overflowing amount, causing the payment to exceed the contract balance and therefore fail when withdraw is attempted.
+
+Recommendation: track the sum of non-withdrawn asyncSends, and don't allow a new one which exceeds the leftover balance. If it's ever desirable to make payments revocable, it should be done explicitly.
+
+## Tokens
+
+### ERC20
+
+Standard ERC20 interface only.
+
+There's a security hole in the standard, reported at Edcon: `approve` does not protect against race conditions and simply replaces the current value. An approved spender could wait for the owner to call `approve` again, then attempt to spend the old limit before the new limit is applied. If successful, this attacker could successfully spend the sum of both limits.
+
+This could be fixed by either (1) including the old limit as a parameter, so the update will fail if some gets spent, or (2) using the value parameter as a delta instead of replacement value.
+
+This is not fixable while adhering to the current full ERC20 standard, though it would be possible to add a "secureApprove" function. The impact isn't extreme since at least you can only be attacked by addresses you approved. Also, users could mitigate this by always setting spending limits to zero and checking for spends, before setting the new limit.
+
+Edcon slides:
+https://drive.google.com/file/d/0ByMtMw2hul0EN3NCaVFHSFdxRzA/view
+
+### ERC20Basic
+
+Simpler interface skipping the Approve function. Note this departs from ERC20 in another way: transfer throws instead of returning false.
+
+### BasicToken
+
+Uses `SafeSub` and `SafeMath`, so transfer `throw`s instead of returning false. This complies with ERC20Basic but not the actual ERC20 standard.
+
+### StandardToken
+
+Implementation of full ERC20 token.
+
+Transfer() and transferFrom() use SafeMath functions, which will cause them to throw instead of returning false. Not a security issue but departs from standard.
+
+### SimpleToken
+
+Sample instantiation of StandardToken. Note that in this sample, decimals is 18 and supply only 10,000, so the supply is a small fraction of a single nominal token.
+
+### CrowdsaleToken
+
+StandardToken which mints tokens at a fixed price when sent ether.
+
+There's no provision for owner withdrawing the ether. As a sample for crowdsales it should be Ownable and allow the owner to withdraw ether, rather than stranding the ether in the contract.
+
+Note: an alternative pattern is a mint() function which is only callable from a separate crowdsale contract, so any sort of rules can be added without modifying the token itself.
+
+### VestedToken
+
+Lines 23, 27:
+Functions `transfer()` and `transferFrom()` have a modifier canTransfer which throws if not enough tokens are available. However, transfer() returns a boolean success. Inconsistent treatment of failure conditions may cause problems for other contracts using the token. (Note that transferableTokens() relies on safeSub(), so will also throw if there's insufficient balance.)
+
+Line 64:
+Delete not actually necessary since the value is overwritten in the next line anyway.
+
+## Root level
+
+### Bounty
+
+Avoids potential race condition by having each researcher deploy a separate contract for attack; if a research manages to break his associated contract, other researchers can't immediately claim the reward, they have to reproduce the attack in their own contracts.
+
+A developer could subvert this intent by implementing `deployContract()` to always return the same address. However, this would break the `researchers` mapping, updating the researcher address associated with the contract. This could be prevented by blocking rewrites in `researchers`.
+
+### DayLimit
+
+The modifier `limitedDaily` calls `underLimit`, which both checks that the spend is below the daily limit, and adds the input value to the daily spend. This is fine if all functions throw upon failure. However, not all OpenZeppelin functions do this; there are functions that returns false, and modifiers that wrap the function body in `if (bool) {_;}`. In these cases, `_value` will be added to `spentToday`, but ether may not actually be sent because other preconditions were not met. (However in the OpenZeppelin multisig this is not a problem.)
+
+Lines 4, 11:
+Comment claims that `DayLimit` is multiowned, and Shareable is imported, but DayLimit does not actually inherit from Shareable. The intent may be for child contracts to inherit from Shareable (as Multisig does); in this case the import should be removed and the comment altered.
+
+Line 46:
+Manual overflow check instead of using safeAdd. Since this is called from a function that throws upon failure anyway, there's no real downside to using safeAdd.
+
+### LimitBalance
+
+No issues.
+
+### MultisigWallet
+
+Lines 28, 76, 80:
+`kill`, `setDailyLimit`, and `resetSpentToday` only happen with multisig approval, and hashes for these actions are logged by Shareable. However, they should probably post their own events for easy reading.
+
+Line 45:
+This call to underLimit will reduce the daily limit, and then either throw or return 0. So in this case there's no danger that the limit will be reduced without the operation going through.
+
+Line 65:
+Shareable's onlyManyOwners will take the user's confirmation, and execute the function body if and only if enough users have confirmed. Whole thing throws if the send fails, which will roll back the confirmation. Confirm returns false if not enough have confirmed yet, true if the whole thing succeeds, and throws only in the exceptional circumstance that the designated transaction unexpectedly fails. Elegant design.
+
+Line 68:
+Throw here is good but note this function can fail either by returning false or by throwing.
+
+Line 92:
+A bit odd to split `clearPending()` between this contract and Shareable. However this does allow contracts inheriting from Shareable to use custom structs for pending transactions.
+
+
+### SafeMath
+
+Another interesting comment from the same Edcon presentation was that the overflow behavior of Solidity is undocumented, so in theory, source code that relies on it could break with a future revision.
+
+However, compiled code should be fine, and in the unlikely event that the compiler is revised in this way, there should be plenty of warning. (But this is an argument for keeping overflow checks isolated in SafeMath.)
+
+Aside from that small caveat, these are fine.
+

certora/Makefile

@@ -0,0 +1,24 @@
+default: help
+
+PATCH         = applyHarness.patch
+CONTRACTS_DIR = ../contracts
+MUNGED_DIR    = munged
+
+help:
+	@echo "usage:"
+	@echo "  make clean:  remove all generated files (those ignored by git)"
+	@echo "  make $(MUNGED_DIR): create $(MUNGED_DIR) directory by applying the patch file to $(CONTRACTS_DIR)"
+	@echo "  make record: record a new patch file capturing the differences between $(CONTRACTS_DIR) and $(MUNGED_DIR)"
+
+munged:  $(wildcard $(CONTRACTS_DIR)/*.sol) $(PATCH)
+	rm -rf $@
+	cp -r $(CONTRACTS_DIR) $@
+	patch -p0 -d $@ < $(PATCH)
+
+record:
+	diff -ruN $(CONTRACTS_DIR) $(MUNGED_DIR) | sed 's+../contracts/++g' | sed 's+munged/++g' > $(PATCH)
+
+clean:
+	git clean -fdX
+	touch $(PATCH)
+

certora/README.md

@@ -0,0 +1,56 @@
+# Running the certora verification tool
+
+These instructions detail the process for running CVT on the OpenZeppelin (Wizard/Governor) contracts.
+
+Documentation for CVT and the specification language are available
+[here](https://certora.atlassian.net/wiki/spaces/CPD/overview)
+
+## Running the verification
+
+The scripts in the `certora/scripts` directory are used to submit verification
+jobs to the Certora verification service. After the job is complete, the results will be available on
+[the Certora portal](https://vaas-stg.certora.com/).
+
+These scripts should be run from the root directory; for example by running
+
+```
+sh certora/scripts/verifyAll.sh <meaningful comment>
+```
+
+The most important of these is `verifyAll.sh`, which checks
+all of the harnessed contracts (`certora/harness/Wizard*.sol`) against all of
+the specifications (`certora/spec/*.spec`).
+
+The other scripts run a subset of the specifications or the contracts.  You can
+verify different contracts or specifications by changing the `--verify` option,
+and you can run a single rule or method with the `--rule` or `--method` option.
+
+For example, to verify the `WizardFirstPriority` contract against the
+`GovernorCountingSimple` specification, you could change the `--verify` line of
+the `WizardControlFirstPriortity.sh` script to:
+
+```
+--verify WizardFirstPriority:certora/specs/GovernorCountingSimple.spec \
+```
+
+## Adapting to changes in the contracts
+
+Some of our rules require the code to be simplified in various ways. Our
+primary tool for performing these simplifications is to run verification on a
+contract that extends the original contracts and overrides some of the methods.
+These "harness" contracts can be found in the `certora/harness` directory.
+
+This pattern does require some modifications to the original code: some methods
+need to be made virtual or public, for example. These changes are handled by
+applying a patch to the code before verification.
+
+When one of the `verify` scripts is executed, it first applies the patch file
+`certora/applyHarness.patch` to the `contracts` directory, placing the output
+in the `certora/munged` directory. We then verify the contracts in the
+`certora/munged` directory.
+
+If the original contracts change, it is possible to create a conflict with the
+patch. In this case, the verify scripts will report an error message and output
+rejected changes in the `munged` directory. After merging the changes, run
+`make record` in the `certora` directory; this will regenerate the patch file,
+which can then be checked into git.

certora/applyHarness.patch

@@ -0,0 +1,101 @@
+diff -ruN .gitignore .gitignore
+--- .gitignore	1969-12-31 19:00:00.000000000 -0500
++++ .gitignore	2021-12-09 14:46:33.923637220 -0500
+@@ -0,0 +1,2 @@
++*
++!.gitignore
+diff -ruN governance/compatibility/GovernorCompatibilityBravo.sol governance/compatibility/GovernorCompatibilityBravo.sol
+--- governance/compatibility/GovernorCompatibilityBravo.sol	2021-12-03 15:24:56.523654357 -0500
++++ governance/compatibility/GovernorCompatibilityBravo.sol	2021-12-09 14:46:33.923637220 -0500
+@@ -245,7 +245,7 @@
+     /**
+      * @dev See {Governor-_quorumReached}. In this module, only forVotes count toward the quorum.
+      */
+-    function _quorumReached(uint256 proposalId) internal view virtual override returns (bool) {
++    function _quorumReached(uint256 proposalId) public view virtual override returns (bool) { // HARNESS: changed to public from internal
+         ProposalDetails storage details = _proposalDetails[proposalId];
+         return quorum(proposalSnapshot(proposalId)) <= details.forVotes;
+     }
+@@ -253,7 +253,7 @@
+     /**
+      * @dev See {Governor-_voteSucceeded}. In this module, the forVotes must be scritly over the againstVotes.
+      */
+-    function _voteSucceeded(uint256 proposalId) internal view virtual override returns (bool) {
++    function _voteSucceeded(uint256 proposalId) public view virtual override returns (bool) { // HARNESS: changed to public from internal
+         ProposalDetails storage details = _proposalDetails[proposalId];
+         return details.forVotes > details.againstVotes;
+     }
+diff -ruN governance/extensions/GovernorCountingSimple.sol governance/extensions/GovernorCountingSimple.sol
+--- governance/extensions/GovernorCountingSimple.sol	2021-12-03 15:24:56.523654357 -0500
++++ governance/extensions/GovernorCountingSimple.sol	2021-12-09 14:46:33.923637220 -0500
+@@ -64,7 +64,7 @@
+     /**
+      * @dev See {Governor-_quorumReached}.
+      */
+-    function _quorumReached(uint256 proposalId) internal view virtual override returns (bool) {
++    function _quorumReached(uint256 proposalId) public view virtual override returns (bool) {
+         ProposalVote storage proposalvote = _proposalVotes[proposalId];
+ 
+         return quorum(proposalSnapshot(proposalId)) <= proposalvote.forVotes + proposalvote.abstainVotes;
+@@ -73,7 +73,7 @@
+     /**
+      * @dev See {Governor-_voteSucceeded}. In this module, the forVotes must be strictly over the againstVotes.
+      */
+-    function _voteSucceeded(uint256 proposalId) internal view virtual override returns (bool) {
++    function _voteSucceeded(uint256 proposalId) public view virtual override returns (bool) {
+         ProposalVote storage proposalvote = _proposalVotes[proposalId];
+ 
+         return proposalvote.forVotes > proposalvote.againstVotes;
+diff -ruN governance/extensions/GovernorTimelockControl.sol governance/extensions/GovernorTimelockControl.sol
+--- governance/extensions/GovernorTimelockControl.sol	2021-12-03 15:24:56.523654357 -0500
++++ governance/extensions/GovernorTimelockControl.sol	2021-12-09 14:46:33.923637220 -0500
+@@ -111,7 +111,7 @@
+         bytes[] memory calldatas,
+         bytes32 descriptionHash
+     ) internal virtual override {
+-        _timelock.executeBatch{value: msg.value}(targets, values, calldatas, 0, descriptionHash);
++         _timelock.executeBatch{value: msg.value}(targets, values, calldatas, 0, descriptionHash);
+     }
+ 
+     /**
+diff -ruN governance/Governor.sol governance/Governor.sol
+--- governance/Governor.sol	2021-12-03 15:24:56.523654357 -0500
++++ governance/Governor.sol	2021-12-09 14:46:56.411503587 -0500
+@@ -38,8 +38,8 @@
+ 
+     string private _name;
+ 
+-    mapping(uint256 => ProposalCore) private _proposals;
+-
++    mapping(uint256 => ProposalCore) public _proposals;
++ 
+     /**
+      * @dev Restrict access to governor executing address. Some module might override the _executor function to make
+      * sure this modifier is consistant with the execution model.
+@@ -167,12 +167,12 @@
+     /**
+      * @dev Amount of votes already cast passes the threshold limit.
+      */
+-    function _quorumReached(uint256 proposalId) internal view virtual returns (bool);
++    function _quorumReached(uint256 proposalId) public view virtual returns (bool); // HARNESS: changed to public from internal
+ 
+     /**
+      * @dev Is the proposal successful or not.
+      */
+-    function _voteSucceeded(uint256 proposalId) internal view virtual returns (bool);
++    function _voteSucceeded(uint256 proposalId) public view virtual returns (bool); // HARNESS: changed to public from internal
+ 
+     /**
+      * @dev Register a vote with a given support and voting weight.
+diff -ruN token/ERC20/extensions/ERC20Votes.sol token/ERC20/extensions/ERC20Votes.sol
+--- token/ERC20/extensions/ERC20Votes.sol	2021-12-03 15:24:56.527654330 -0500
++++ token/ERC20/extensions/ERC20Votes.sol	2021-12-09 14:46:33.927637196 -0500
+@@ -84,7 +84,7 @@
+      *
+      * - `blockNumber` must have been already mined
+      */
+-    function getPastVotes(address account, uint256 blockNumber) public view returns (uint256) {
++    function getPastVotes(address account, uint256 blockNumber) public view virtual returns (uint256) {
+         require(blockNumber < block.number, "ERC20Votes: block not yet mined");
+         return _checkpointsLookup(_checkpoints[account], blockNumber);
+     }

certora/harnesses/ERC20VotesHarness.sol

@@ -0,0 +1,28 @@
+import "../munged/token/ERC20/extensions/ERC20Votes.sol";
+
+contract ERC20VotesHarness is ERC20Votes {
+    constructor(string memory name, string memory symbol) ERC20Permit(name) ERC20(name, symbol) {}
+
+    mapping(address => mapping(uint256 => uint256)) public _getPastVotes;
+
+    function _afterTokenTransfer(
+        address from,
+        address to,
+        uint256 amount
+    ) internal virtual override {
+        super._afterTokenTransfer(from, to, amount);
+        _getPastVotes[from][block.number] -= amount;
+        _getPastVotes[to][block.number] += amount;
+    }
+
+    /**
+     * @dev Change delegation for `delegator` to `delegatee`.
+     *
+     * Emits events {DelegateChanged} and {DelegateVotesChanged}.
+     */
+    function _delegate(address delegator, address delegatee) internal virtual override{
+        super._delegate(delegator, delegatee);
+        _getPastVotes[delegator][block.number] -= balanceOf(delegator);
+        _getPastVotes[delegatee][block.number] += balanceOf(delegator);
+    }
+}

certora/harnesses/WizardControlFirstPriority.sol

@@ -0,0 +1,150 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.2;
+
+import "../munged/governance/Governor.sol";
+import "../munged/governance/extensions/GovernorCountingSimple.sol";
+import "../munged/governance/extensions/GovernorVotes.sol";
+import "../munged/governance/extensions/GovernorVotesQuorumFraction.sol";
+import "../munged/governance/extensions/GovernorTimelockControl.sol";
+import "../munged/governance/extensions/GovernorProposalThreshold.sol";
+
+/* 
+Wizard options:
+ProposalThreshhold = 10
+ERC20Votes
+TimelockController
+*/
+
+contract WizardControlFirstPriority is Governor, GovernorProposalThreshold, GovernorCountingSimple, GovernorVotes, GovernorVotesQuorumFraction, GovernorTimelockControl {
+    constructor(ERC20Votes _token, TimelockController _timelock, string memory name, uint256 quorumFraction)
+        Governor(name)
+        GovernorVotes(_token)
+        GovernorVotesQuorumFraction(quorumFraction)
+        GovernorTimelockControl(_timelock)
+    {}
+
+    //HARNESS
+
+    function isExecuted(uint256 proposalId) public view returns (bool) {
+        return _proposals[proposalId].executed;
+    }
+    
+    function isCanceled(uint256 proposalId) public view returns (bool) {
+        return _proposals[proposalId].canceled;
+    }
+
+    uint256 _votingDelay;
+
+    uint256 _votingPeriod;
+
+    uint256 _proposalThreshold;
+
+    mapping(uint256 => uint256) public ghost_sum_vote_power_by_id;
+
+    function _castVote(
+        uint256 proposalId,
+        address account,
+        uint8 support,
+        string memory reason
+    ) internal override virtual returns (uint256) {
+        
+        uint256 deltaWeight = super._castVote(proposalId, account, support, reason);  //HARNESS
+        ghost_sum_vote_power_by_id[proposalId] += deltaWeight;
+
+        return deltaWeight;        
+    }
+    
+    function snapshot(uint256 proposalId) public view returns (uint64) {
+        return _proposals[proposalId].voteStart._deadline;
+    }
+
+
+    function getExecutor() public view returns (address){
+        return _executor();
+    }
+
+    // original code, harnessed
+
+    function votingDelay() public view override returns (uint256) {     // HARNESS: pure -> view
+        return _votingDelay;                                            // HARNESS: parametric
+    }
+
+    function votingPeriod() public view override returns (uint256) {    // HARNESS: pure -> view
+        return _votingPeriod;                                           // HARNESS: parametric
+    }
+
+    function proposalThreshold() public view override returns (uint256) {   // HARNESS: pure -> view
+        return _proposalThreshold;                                          // HARNESS: parametric
+    }
+
+    // original code, not harnessed
+    // The following functions are overrides required by Solidity.
+
+    function quorum(uint256 blockNumber)
+        public
+        view
+        override(IGovernor, GovernorVotesQuorumFraction)
+        returns (uint256)
+    {
+        return super.quorum(blockNumber);
+    }
+
+    function getVotes(address account, uint256 blockNumber)
+        public
+        view
+        override(IGovernor, GovernorVotes)
+        returns (uint256)
+    {
+        return super.getVotes(account, blockNumber);
+    }
+
+    function state(uint256 proposalId)
+        public
+        view
+        override(Governor, GovernorTimelockControl)
+        returns (ProposalState)
+    {
+        return super.state(proposalId);
+    }
+
+    function propose(address[] memory targets, uint256[] memory values, bytes[] memory calldatas, string memory description)
+        public
+        override(Governor, GovernorProposalThreshold, IGovernor)
+        returns (uint256)
+    {
+        return super.propose(targets, values, calldatas, description);
+    }
+
+    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, GovernorTimelockControl)
+        returns (bool)
+    {
+        return super.supportsInterface(interfaceId);
+    }
+}

certora/harnesses/WizardFirstTry.sol

@@ -0,0 +1,141 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.2;
+
+import "../munged/governance/Governor.sol";
+import "../munged/governance/extensions/GovernorCountingSimple.sol";
+import "../munged/governance/extensions/GovernorVotes.sol";
+import "../munged/governance/extensions/GovernorVotesQuorumFraction.sol";
+import "../munged/governance/extensions/GovernorTimelockCompound.sol";
+
+/* 
+Wizard options:
+ERC20Votes
+TimelockCompound
+*/
+
+contract WizardFirstTry is Governor, GovernorCountingSimple, GovernorVotes, GovernorVotesQuorumFraction, GovernorTimelockCompound {
+    constructor(ERC20Votes _token, ICompoundTimelock _timelock, string memory name, uint256 quorumFraction)
+        Governor(name)
+        GovernorVotes(_token)
+        GovernorVotesQuorumFraction(quorumFraction)
+        GovernorTimelockCompound(_timelock)
+    {}
+
+    //HARNESS
+
+    function isExecuted(uint256 proposalId) public view returns (bool) {
+        return _proposals[proposalId].executed;
+    }
+    
+    function isCanceled(uint256 proposalId) public view returns (bool) {
+        return _proposals[proposalId].canceled;
+    }
+
+    function snapshot(uint256 proposalId) public view returns (uint64) {
+        return _proposals[proposalId].voteStart._deadline;
+    }
+
+    function getExecutor() public view returns (address){
+        return _executor();
+    }
+
+    uint256 _votingDelay;
+
+    uint256 _votingPeriod;
+
+    mapping(uint256 => uint256) public ghost_sum_vote_power_by_id;
+
+    function _castVote(
+        uint256 proposalId,
+        address account,
+        uint8 support,
+        string memory reason
+    ) internal override virtual returns (uint256) {
+        
+        uint256 deltaWeight = super._castVote(proposalId, account, support, reason);  //HARNESS
+        ghost_sum_vote_power_by_id[proposalId] += deltaWeight;
+
+        return deltaWeight;        
+    }
+
+    // original code, harnessed
+
+    function votingDelay() public view override virtual returns (uint256) {     // HARNESS: pure -> view
+        return _votingDelay;                                                    // HARNESS: parametric
+    }
+
+    function votingPeriod() public view override virtual returns (uint256) {    // HARNESS: pure -> view
+        return _votingPeriod;                                                   // HARNESS: parametric
+    }
+
+    // original code, not harnessed
+    // The following functions are overrides required by Solidity.
+
+    function quorum(uint256 blockNumber)
+        public
+        view
+        override(IGovernor, GovernorVotesQuorumFraction)
+        returns (uint256)
+    {
+        return super.quorum(blockNumber);
+    }
+
+    function getVotes(address account, uint256 blockNumber)
+        public
+        view
+        override(IGovernor, GovernorVotes)
+        returns (uint256)
+    {
+        return super.getVotes(account, blockNumber);
+    }
+
+    function state(uint256 proposalId)
+        public
+        view
+        override(Governor, GovernorTimelockCompound)
+        returns (ProposalState)
+    {
+        return super.state(proposalId);
+    }
+
+    function propose(address[] memory targets, uint256[] memory values, bytes[] memory calldatas, string memory description)
+        public
+        override(Governor, IGovernor)
+        returns (uint256)
+    {
+        return super.propose(targets, values, calldatas, description);
+    }
+
+    function _execute(uint256 proposalId, address[] memory targets, uint256[] memory values, bytes[] memory calldatas, bytes32 descriptionHash)
+        internal
+        override(Governor, GovernorTimelockCompound)
+    {
+        super._execute(proposalId, targets, values, calldatas, descriptionHash);
+    }
+
+    function _cancel(address[] memory targets, uint256[] memory values, bytes[] memory calldatas, bytes32 descriptionHash)
+        internal
+        override(Governor, GovernorTimelockCompound)
+        returns (uint256)
+    {
+        return super._cancel(targets, values, calldatas, descriptionHash);
+    }
+
+    function _executor()
+        internal
+        view
+        override(Governor, GovernorTimelockCompound)
+        returns (address)
+    {
+        return super._executor();
+    }
+
+    function supportsInterface(bytes4 interfaceId)
+        public
+        view
+        override(Governor, GovernorTimelockCompound)
+        returns (bool)
+    {
+        return super.supportsInterface(interfaceId);
+    }
+}

certora/munged/.gitignore

@@ -0,0 +1,2 @@
+*
+!.gitignore

certora/scripts/Governor.sh

@@ -0,0 +1,10 @@
+make -C certora munged
+
+certoraRun certora/harnesses/ERC20VotesHarness.sol certora/harnesses/GovernorHarness.sol \
+    --verify GovernorHarness:certora/specs/GovernorBase.spec \
+    --solc solc8.0 \
+    --staging shelly/forSasha \
+    --optimistic_loop \
+    --settings -copyLoopUnroll=4 \
+    --rule voteStartBeforeVoteEnd \
+    --msg "$1"

certora/scripts/GovernorCountingSimple-counting.sh

@@ -0,0 +1,10 @@
+make -C certora munged
+
+certoraRun  certora/harnesses/ERC20VotesHarness.sol certora/harnesses/GovernorBasicHarness.sol \
+    --verify GovernorBasicHarness:certora/specs/GovernorCountingSimple.spec \
+    --solc solc8.2 \
+    --staging shelly/forSasha \
+    --optimistic_loop \
+    --settings -copyLoopUnroll=4 \
+    --rule hasVotedCorrelation \
+    --msg "$1"

certora/scripts/WizardControlFirstPriority.sh

@@ -0,0 +1,12 @@
+make -C certora munged
+
+certoraRun certora/harnesses/ERC20VotesHarness.sol certora/harnesses/WizardControlFirstPriority.sol \
+    --link WizardControlFirstPriority:token=ERC20VotesHarness \
+    --verify WizardControlFirstPriority:certora/specs/GovernorBase.spec \
+    --solc solc8.2 \
+    --disableLocalTypeChecking \
+    --staging shelly/forSasha \
+    --optimistic_loop \
+    --settings -copyLoopUnroll=4 \
+    --rule canVoteDuringVotingPeriod \
+    --msg "$1"

certora/scripts/WizardFirstTry.sh

@@ -0,0 +1,10 @@
+make -C certora munged
+
+certoraRun certora/harnesses/ERC20VotesHarness.sol certora/harnesses/WizardFirstTry.sol \
+    --verify WizardFirstTry:certora/specs/GovernorBase.spec \
+    --solc solc8.2 \
+    --staging shelly/forSasha \
+    --optimistic_loop \
+    --disableLocalTypeChecking \
+    --settings -copyLoopUnroll=4 \
+    --msg "$1"

certora/scripts/sanity.sh

@@ -0,0 +1,14 @@
+make -C certora munged
+
+for f in certora/harnesses/Wizard*.sol
+do
+    echo "Processing $f"
+    file=$(basename $f)
+    echo ${file%.*}
+    certoraRun certora/harnesses/$file \
+    --verify ${file%.*}:certora/specs/sanity.spec "$@" \
+    --solc solc8.2 --staging shelly/forSasha \
+    --optimistic_loop \
+    --msg "checking sanity on ${file%.*}"
+    --settings -copyLoopUnroll=4
+done

certora/scripts/verifyAll.sh

@@ -0,0 +1,39 @@
+#!/bin/bash
+
+make -C certora munged
+
+for contract in certora/harnesses/Wizard*.sol;
+do
+    for spec in certora/specs/*.spec;
+    do      
+        contractFile=$(basename $contract)
+        specFile=$(basename $spec)
+        if [[ "${specFile%.*}" != "RulesInProgress" ]];
+        then
+            echo "Processing ${contractFile%.*} with $specFile"
+            if [[ "${contractFile%.*}" = *"WizardControl"* ]];
+            then
+                certoraRun certora/harnesses/ERC20VotesHarness.sol certora/harnesses/$contractFile \
+                --link ${contractFile%.*}:token=ERC20VotesHarness \
+                --verify ${contractFile%.*}:certora/specs/$specFile "$@" \
+                --solc solc8.2 \
+                --staging shelly/forSasha \
+                --disableLocalTypeChecking \
+                --optimistic_loop \
+                --settings -copyLoopUnroll=4 \
+                --send_only \
+                --msg "checking $specFile on ${contractFile%.*}"
+            else
+                certoraRun certora/harnesses/ERC20VotesHarness.sol certora/harnesses/$contractFile \
+                --verify ${contractFile%.*}:certora/specs/$specFile "$@" \
+                --solc solc8.2 \
+                --staging shelly/forSasha \
+                --disableLocalTypeChecking \
+                --optimistic_loop \
+                --settings -copyLoopUnroll=4 \
+                --send_only \
+                --msg "checking $specFile on ${contractFile%.*}"
+            fi
+        fi
+    done
+done

certora/specs/GovernorBase.spec

@@ -0,0 +1,334 @@
+//////////////////////////////////////////////////////////////////////////////
+///////////////////// Governor.sol base definitions //////////////////////////
+//////////////////////////////////////////////////////////////////////////////
+
+using ERC20VotesHarness as erc20votes
+
+methods {
+    proposalSnapshot(uint256) returns uint256 envfree // matches proposalVoteStart
+    proposalDeadline(uint256) returns uint256 envfree // matches proposalVoteEnd
+    hashProposal(address[],uint256[],bytes[],bytes32) returns uint256 envfree
+    isExecuted(uint256) returns bool envfree
+    isCanceled(uint256) returns bool envfree
+    execute(address[], uint256[], bytes[], bytes32) returns uint256
+    hasVoted(uint256, address) returns bool
+    castVote(uint256, uint8) returns uint256
+    updateQuorumNumerator(uint256)
+    queue(address[], uint256[], bytes[], bytes32) returns uint256
+
+    // internal functions made public in harness:
+    _quorumReached(uint256) returns bool
+    _voteSucceeded(uint256) returns bool envfree
+
+    // function summarization
+    proposalThreshold() returns uint256 envfree
+
+    getVotes(address, uint256) returns uint256 => DISPATCHER(true)
+
+    getPastTotalSupply(uint256 t) returns uint256      => PER_CALLEE_CONSTANT
+    getPastVotes(address a, uint256 t) returns uint256 => PER_CALLEE_CONSTANT
+
+    //scheduleBatch(address[],uint256[],bytes[],bytes32,bytes32,uint256) => DISPATCHER(true)
+    //executeBatch(address[], uint256[], bytes[], bytes32, bytes32) => DISPATCHER(true)
+}
+
+//////////////////////////////////////////////////////////////////////////////
+//////////////////////////////// Definitions /////////////////////////////////
+//////////////////////////////////////////////////////////////////////////////
+
+
+// proposal was created - relation proved in noStartBeforeCreation
+definition proposalCreated(uint256 pId) returns bool = proposalSnapshot(pId) > 0;
+
+
+//////////////////////////////////////////////////////////////////////////////
+///////////////////////////// Helper Functions ///////////////////////////////
+//////////////////////////////////////////////////////////////////////////////
+
+function helperFunctionsWithRevert(uint256 proposalId, method f, env e) {
+    address[] targets; uint256[] values; bytes[] calldatas; string reason; bytes32 descriptionHash;
+    uint8 support; uint8 v; bytes32 r; bytes32 s;
+	if (f.selector == propose(address[], uint256[], bytes[], string).selector) {
+		uint256 result = propose@withrevert(e, targets, values, calldatas, reason);
+        require(result == proposalId);
+	} else if (f.selector == execute(address[], uint256[], bytes[], bytes32).selector) {
+		uint256 result = execute@withrevert(e, targets, values, calldatas, descriptionHash);
+        require(result == proposalId);
+	} else if (f.selector == castVote(uint256, uint8).selector) {
+		castVote@withrevert(e, proposalId, support);
+	} else if  (f.selector == castVoteWithReason(uint256, uint8, string).selector) {
+        castVoteWithReason@withrevert(e, proposalId, support, reason);
+	} else if (f.selector == castVoteBySig(uint256, uint8,uint8, bytes32, bytes32).selector) {
+		castVoteBySig@withrevert(e, proposalId, support, v, r, s);
+    } else if (f.selector == queue(address[], uint256[], bytes[], bytes32).selector) {
+        queue@withrevert(e, targets, values, calldatas, descriptionHash);
+	} else {
+        calldataarg args;
+        f@withrevert(e, args);
+    }
+}
+
+/*
+ //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+ ///////////////////////////////////////////////////// State Diagram //////////////////////////////////////////////////////////
+ //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+ //                                                                                                                          //
+ //                                                                castVote(s)()                                             //
+ //  -------------  propose()  ----------------------  time pass  ---------------       time passes         -----------      //
+ // | No Proposal | --------> | Before Start (Delay) | --------> | Voting Period | ----------------------> | execute() |     //
+ //  -------------             ----------------------             --------------- -> Executed/Canceled      -----------      //
+ //  ------------------------------------------------------------|---------------|-------------------------|-------------->  //
+ // t                                                          start            end                     timelock             //
+ //                                                                                                                          //
+ //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+*/
+
+
+///////////////////////////////////////////////////////////////////////////////////////
+///////////////////////////////// Global Valid States /////////////////////////////////
+///////////////////////////////////////////////////////////////////////////////////////
+
+
+/*
+ * Start and end date are either initialized (non zero) or uninitialized (zero) simultaneously
+ * This invariant assumes that the block number cannot be 0 at any stage of the contract cycle
+ * This is very safe assumption as usually the 0 block is genesis block which is uploaded with data
+ * by the developers and will not be valid to raise proposals (at the current way that block chain is functioning)
+ */
+ // To use env with general preserved block disable type checking [--disableLocalTypeChecking]
+invariant startAndEndDatesNonZero(uint256 pId)
+        proposalSnapshot(pId) != 0 <=> proposalDeadline(pId) != 0
+        { preserved with (env e){   
+                require e.block.number > 0;
+        }}
+        
+
+/*
+ * If a proposal is canceled it must have a start and an end date 
+ */
+ // To use env with general preserved block disable type checking [--disableLocalTypeChecking]
+invariant canceledImplyStartAndEndDateNonZero(uint pId)
+        isCanceled(pId) => proposalSnapshot(pId) != 0
+        {preserved with (env e){               
+                require e.block.number > 0;
+        }}
+
+
+/*
+ * If a proposal is executed it must have a start and an end date 
+ */
+ // To use env with general preserved block disable type checking [--disableLocalTypeChecking] 
+invariant executedImplyStartAndEndDateNonZero(uint pId)
+        isExecuted(pId) => proposalSnapshot(pId) != 0
+        { preserved with (env e){
+            requireInvariant startAndEndDatesNonZero(pId);
+            require e.block.number > 0;
+        }}
+
+
+/*
+ * A proposal starting block number must be less or equal than the proposal end date
+ */
+invariant voteStartBeforeVoteEnd(uint256 pId)
+        // from < to <= because snapshot and deadline can be the same block number if delays are set to 0
+        // This is possible before the integration of GovernorSettings.sol to the system.
+        // After integration of GovernorSettings.sol the invariant expression should be changed from <= to <
+        (proposalSnapshot(pId) > 0 =>  proposalSnapshot(pId) <= proposalDeadline(pId))
+        // (proposalSnapshot(pId) > 0 =>  proposalSnapshot(pId) <= proposalDeadline(pId))
+        { preserved {
+            requireInvariant startAndEndDatesNonZero(pId);
+        }}
+
+
+/*
+ * A proposal cannot be both executed and canceled simultaneously.
+ */
+invariant noBothExecutedAndCanceled(uint256 pId) 
+        !isExecuted(pId) || !isCanceled(pId)
+
+
+/*
+ * A proposal could be executed only if quorum was reached and vote succeeded
+ */
+rule executionOnlyIfQuoromReachedAndVoteSucceeded(uint256 pId, env e, method f){
+    bool isExecutedBefore = isExecuted(pId);
+    bool quorumReachedBefore = _quorumReached(e, pId);
+    bool voteSucceededBefore = _voteSucceeded(pId);
+    
+    calldataarg args;
+    f(e, args);
+    
+    bool isExecutedAfter = isExecuted(pId);
+    assert (!isExecutedBefore && isExecutedAfter) => (quorumReachedBefore && voteSucceededBefore), "quorum was changed";
+}
+
+///////////////////////////////////////////////////////////////////////////////////////
+////////////////////////////////// In-State Rules /////////////////////////////////////
+///////////////////////////////////////////////////////////////////////////////////////
+
+//==========================================
+//------------- Voting Period --------------
+//==========================================
+
+/*
+ * A user cannot vote twice
+ */
+ // Checked for castVote only. all 3 castVote functions call _castVote, so the completness of the verification is counted on
+ // the fact that the 3 functions themselves makes no chages, but rather call an internal function to execute.
+ // That means that we do not check those 3 functions directly, however for castVote & castVoteWithReason it is quite trivial
+ // to understand why this is ok. For castVoteBySig we basically assume that the signature referendum is correct without checking it.
+ // We could check each function seperately and pass the rule, but that would have uglyfied the code with no concrete 
+ // benefit, as it is evident that nothing is happening in the first 2 functions (calling a view function), and we do not desire to check the signature verification.
+rule doubleVoting(uint256 pId, uint8 sup, method f) {
+    env e;
+    address user = e.msg.sender;        
+    bool votedCheck = hasVoted(e, pId, user);
+
+    castVote@withrevert(e, pId, sup);
+
+    assert votedCheck => lastReverted, "double voting accured";
+}
+
+
+///////////////////////////////////////////////////////////////////////////////////////
+//////////////////////////// State Transitions Rules //////////////////////////////////
+///////////////////////////////////////////////////////////////////////////////////////
+
+//===========================================
+//-------- Propose() --> End of Time --------
+//===========================================
+
+
+/*
+ * Once a proposal is created, voteStart and voteEnd are immutable
+ */
+rule immutableFieldsAfterProposalCreation(uint256 pId, method f) {
+    uint256 _voteStart = proposalSnapshot(pId);
+    uint256 _voteEnd = proposalDeadline(pId);
+
+    require proposalCreated(pId); // startDate > 0
+    
+    env e; calldataarg arg;
+    f(e, arg);
+
+    uint256 voteStart_ = proposalSnapshot(pId);
+    uint256 voteEnd_ = proposalDeadline(pId);
+    assert _voteStart == voteStart_, "Start date was changed";
+    assert _voteEnd == voteEnd_, "End date was changed";
+}
+
+
+/*
+ * Voting cannot start at a block number prior to proposal’s creation block number
+ */
+rule noStartBeforeCreation(uint256 pId) {
+    uint256 previousStart = proposalSnapshot(pId);
+    // This line makes sure that we see only cases where start date is changed from 0, i.e. creation of proposal
+    // We proved in immutableFieldsAfterProposalCreation that once dates set for proposal, it cannot be changed
+    require !proposalCreated(pId); // previousStart == 0;
+    
+    env e; calldataarg args;
+    propose(e, args);
+
+    uint256 newStart = proposalSnapshot(pId);
+    // if created, start is after current block number (creation block)
+    assert(newStart != previousStart => newStart >= e.block.number);
+}
+
+
+//============================================
+//--- End of Voting Period --> End of Time ---
+//============================================
+
+
+/*
+ * A proposal can neither be executed nor canceled before it ends
+ */
+ // By induction it cannot be executed nor canceled before it starts, due to voteStartBeforeVoteEnd
+rule noExecuteOrCancelBeforeDeadline(uint256 pId, method f){
+    require !isExecuted(pId) && !isCanceled(pId);
+
+    env e; calldataarg args;
+    f(e, args);
+
+    assert e.block.number < proposalDeadline(pId) => (!isExecuted(pId) && !isCanceled(pId)), "executed/cancelled before deadline";
+}
+
+////////////////////////////////////////////////////////////////////////////////
+////////////////////// Integrity Of Functions (Unit Tests) /////////////////////
+////////////////////////////////////////////////////////////////////////////////
+
+
+////////////////////////////////////////////////////////////////////////////////
+////////////////////////////// High Level Rules ////////////////////////////////
+////////////////////////////////////////////////////////////////////////////////
+
+
+////////////////////////////////////////////////////////////////////////////////
+///////////////////////////// Not Categorized Yet //////////////////////////////
+////////////////////////////////////////////////////////////////////////////////
+
+
+/*
+ * All proposal specific (non-view) functions should revert if proposal is executed
+ */
+ // In this rule we show that if a function is executed, i.e. execute() was called on the proposal ID,
+ // non of the proposal specific functions can make changes again. In executedOnlyAfterExecuteFunc 
+ // we connected the executed attribute to the execute() function, showing that only execute() can
+ // change it, and that it will always change it.
+rule allFunctionsRevertIfExecuted(method f) filtered { f ->
+    !f.isView && !f.isFallback
+      && f.selector != updateTimelock(address).selector
+      && f.selector != updateQuorumNumerator(uint256).selector
+      && f.selector != queue(address[],uint256[],bytes[],bytes32).selector
+      && f.selector != relay(address,uint256,bytes).selector
+      && f.selector != 0xb9a61961 // __acceptAdmin()
+} {
+    env e; calldataarg args;
+    uint256 pId;
+    require(isExecuted(pId));
+    requireInvariant noBothExecutedAndCanceled(pId);
+    requireInvariant executedImplyStartAndEndDateNonZero(pId);
+
+    helperFunctionsWithRevert(pId, f, e);
+
+    assert(lastReverted, "Function was not reverted");
+}
+
+/*
+ * All proposal specific (non-view) functions should revert if proposal is canceled
+ */
+rule allFunctionsRevertIfCanceled(method f) filtered {
+    f -> !f.isView && !f.isFallback
+      && f.selector != updateTimelock(address).selector
+      && f.selector != updateQuorumNumerator(uint256).selector
+      && f.selector != queue(address[],uint256[],bytes[],bytes32).selector
+      && f.selector != relay(address,uint256,bytes).selector
+      && f.selector != 0xb9a61961 // __acceptAdmin()
+} {
+    env e; calldataarg args;
+    uint256 pId;
+    require(isCanceled(pId));
+    requireInvariant noBothExecutedAndCanceled(pId);
+    requireInvariant canceledImplyStartAndEndDateNonZero(pId);
+
+    helperFunctionsWithRevert(pId, f, e);
+
+    assert(lastReverted, "Function was not reverted");
+}
+
+/*
+ * Proposal can be switched to executed only via execute() function
+ */
+rule executedOnlyAfterExecuteFunc(address[] targets, uint256[] values, bytes[] calldatas, bytes32 descriptionHash, method f) {
+    env e; calldataarg args;
+    uint256 pId;
+    bool executedBefore = isExecuted(pId);
+    require(!executedBefore);
+
+    helperFunctionsWithRevert(pId, f, e);
+
+    bool executedAfter = isExecuted(pId);
+    assert(executedAfter != executedBefore => f.selector == execute(address[], uint256[], bytes[], bytes32).selector, "isExecuted only changes in the execute method");
+}
+

certora/specs/GovernorCountingSimple.spec

@@ -0,0 +1,221 @@
+import "GovernorBase.spec"
+
+using ERC20VotesHarness as erc20votes
+
+methods {
+    ghost_sum_vote_power_by_id(uint256) returns uint256 envfree
+
+    quorum(uint256) returns uint256
+    proposalVotes(uint256) returns (uint256, uint256, uint256) envfree
+
+    quorumNumerator() returns uint256
+    _executor() returns address
+
+    erc20votes._getPastVotes(address, uint256) returns uint256
+
+    getExecutor() returns address
+
+    timelock() returns address
+}
+
+
+//////////////////////////////////////////////////////////////////////////////
+///////////////////////////////// GHOSTS /////////////////////////////////////
+//////////////////////////////////////////////////////////////////////////////
+
+
+//////////// ghosts to keep track of votes counting ////////////
+
+/*
+ * the sum of voting power of those who voted
+ */
+ghost sum_all_votes_power() returns uint256 {
+	init_state axiom sum_all_votes_power() == 0;
+}
+
+hook Sstore ghost_sum_vote_power_by_id [KEY uint256 pId] uint256 current_power(uint256 old_power) STORAGE {
+	havoc sum_all_votes_power assuming sum_all_votes_power@new() == sum_all_votes_power@old() - old_power + current_power;
+}
+
+/*
+ * sum of all votes casted per proposal
+ */
+ghost tracked_weight(uint256) returns uint256 {
+	init_state axiom forall uint256 p. tracked_weight(p) == 0;
+}
+
+/*
+ * sum of all votes casted
+ */
+ghost sum_tracked_weight() returns uint256 {
+	init_state axiom sum_tracked_weight() == 0;
+}
+
+/*
+ * getter for _proposalVotes.againstVotes
+ */
+ghost votesAgainst() returns uint256 {
+    init_state axiom votesAgainst() == 0;
+}
+
+/*
+ * getter for _proposalVotes.forVotes
+ */
+ghost votesFor() returns uint256 {
+    init_state axiom votesFor() == 0;
+}
+
+/*
+ * getter for _proposalVotes.abstainVotes
+ */
+ghost votesAbstain() returns uint256 {
+    init_state axiom votesAbstain() == 0;
+}
+
+hook Sstore _proposalVotes [KEY uint256 pId].againstVotes uint256 votes(uint256 old_votes) STORAGE {
+	havoc tracked_weight assuming forall uint256 p.(p == pId => tracked_weight@new(p) == tracked_weight@old(p) - old_votes + votes) &&
+	                                            (p != pId => tracked_weight@new(p) == tracked_weight@old(p));
+	havoc sum_tracked_weight assuming sum_tracked_weight@new() == sum_tracked_weight@old() - old_votes + votes;
+    havoc votesAgainst assuming votesAgainst@new() == votesAgainst@old() - old_votes + votes;
+}
+
+hook Sstore _proposalVotes [KEY uint256 pId].forVotes uint256 votes(uint256 old_votes) STORAGE {
+	havoc tracked_weight assuming forall uint256 p.(p == pId => tracked_weight@new(p) == tracked_weight@old(p) - old_votes + votes) &&
+	                                            (p != pId => tracked_weight@new(p) == tracked_weight@old(p));
+	havoc sum_tracked_weight assuming sum_tracked_weight@new() == sum_tracked_weight@old() - old_votes + votes;
+    havoc votesFor assuming votesFor@new() == votesFor@old() - old_votes + votes;
+}
+
+hook Sstore _proposalVotes [KEY uint256 pId].abstainVotes uint256 votes(uint256 old_votes) STORAGE {
+	havoc tracked_weight assuming forall uint256 p.(p == pId => tracked_weight@new(p) == tracked_weight@old(p) - old_votes + votes) &&
+	                                            (p != pId => tracked_weight@new(p) == tracked_weight@old(p));
+	havoc sum_tracked_weight assuming sum_tracked_weight@new() == sum_tracked_weight@old() - old_votes + votes;
+    havoc votesAbstain assuming votesAbstain@new() == votesAbstain@old() - old_votes + votes;
+}
+
+
+//////////////////////////////////////////////////////////////////////////////
+////////////////////////////// INVARIANTS ////////////////////////////////////
+//////////////////////////////////////////////////////////////////////////////
+
+
+/*
+ * sum of all votes casted is equal to the sum of voting power of those who voted, per each proposal
+ */
+invariant SumOfVotesCastEqualSumOfPowerOfVotedPerProposal(uint256 pId) 
+	tracked_weight(pId) == ghost_sum_vote_power_by_id(pId)
+
+
+/*
+ * sum of all votes casted is equal to the sum of voting power of those who voted
+ */
+invariant SumOfVotesCastEqualSumOfPowerOfVoted() 
+	sum_tracked_weight() == sum_all_votes_power()
+
+
+/*
+* sum of all votes casted is greater or equal to the sum of voting power of those who voted at a specific proposal
+*/
+invariant OneIsNotMoreThanAll(uint256 pId) 
+	sum_all_votes_power() >= tracked_weight(pId)
+
+
+//////////////////////////////////////////////////////////////////////////////
+///////////////////////////////// RULES //////////////////////////////////////
+//////////////////////////////////////////////////////////////////////////////
+
+
+/*
+ * Only sender's voting status can be changed by execution of any cast vote function
+ */
+// Checked for castVote only. all 3 castVote functions call _castVote, so the completness of the verification is counted on
+ // the fact that the 3 functions themselves makes no chages, but rather call an internal function to execute.
+ // That means that we do not check those 3 functions directly, however for castVote & castVoteWithReason it is quite trivial
+ // to understand why this is ok. For castVoteBySig we basically assume that the signature referendum is correct without checking it.
+ // We could check each function seperately and pass the rule, but that would have uglyfied the code with no concrete 
+ // benefit, as it is evident that nothing is happening in the first 2 functions (calling a view function), and we do not desire to check the signature verification.
+rule noVoteForSomeoneElse(uint256 pId, uint8 sup, method f) {
+    env e; calldataarg args;
+
+    address voter = e.msg.sender;
+    address user;
+
+    bool hasVotedBefore_User = hasVoted(e, pId, user);
+
+    castVote@withrevert(e, pId, sup);
+    require(!lastReverted);
+
+    bool hasVotedAfter_User = hasVoted(e, pId, user);
+
+    assert user != voter => hasVotedBefore_User == hasVotedAfter_User;
+}
+
+
+/*
+* Total voting tally is monotonically non-decreasing in every operation 
+*/
+rule votingWeightMonotonicity(method f){
+    uint256 votingWeightBefore = sum_tracked_weight();
+
+    env e; 
+    calldataarg args;
+    f(e, args);
+
+    uint256 votingWeightAfter = sum_tracked_weight();
+
+    assert votingWeightBefore <= votingWeightAfter, "Voting weight was decreased somehow";
+}
+
+
+/*
+* A change in hasVoted must be correlated with an non-decreasing of the vote supports (nondecrease because user can vote with weight 0)
+*/
+rule hasVotedCorrelation(uint256 pId, method f, env e, uint256 bn) {
+    address acc = e.msg.sender;
+    
+    uint256 againstBefore = votesAgainst();
+    uint256 forBefore = votesFor();
+    uint256 abstainBefore = votesAbstain();
+
+    bool hasVotedBefore = hasVoted(e, pId, acc);
+
+    helperFunctionsWithRevert(pId, f, e);
+    require(!lastReverted);
+
+    uint256 againstAfter = votesAgainst();
+    uint256 forAfter = votesFor();
+    uint256 abstainAfter = votesAbstain();
+    
+    bool hasVotedAfter = hasVoted(e, pId, acc);
+
+    assert (!hasVotedBefore && hasVotedAfter) => againstBefore <= againstAfter || forBefore <= forAfter || abstainBefore <= abstainAfter, "no correlation";
+}
+
+
+/*
+* Only privileged users can execute privileged operations, e.g. change _quorumNumerator or _timelock
+*/
+rule privilegedOnlyNumerator(method f, uint256 newQuorumNumerator){
+    env e;
+    calldataarg arg;
+    uint256 quorumNumBefore = quorumNumerator(e);
+
+    f(e, arg);
+
+    uint256 quorumNumAfter = quorumNumerator(e);
+    address executorCheck = getExecutor(e);
+
+    assert quorumNumBefore != quorumNumAfter => e.msg.sender == executorCheck, "non priveleged user changed quorum numerator";
+}
+
+rule privilegedOnlyTimelock(method f, uint256 newQuorumNumerator){
+    env e;
+    calldataarg arg;
+    uint256 timelockBefore = timelock(e);
+
+    f(e, arg);
+
+    uint256 timelockAfter = timelock(e);
+
+    assert timelockBefore != timelockAfter => e.msg.sender == timelockBefore, "non priveleged user changed timelock";
+}

certora/specs/RulesInProgress.spec

@@ -0,0 +1,139 @@
+//////////////////////////////////////////////////////////////////////////////
+////////////// THIS SPEC IS A RESERVE FOR NOT IN PROGRESS //////////////
+//////////////////////////////////////////////////////////////////////////////
+
+import "GovernorBase.spec"
+
+using ERC20VotesHarness as erc20votes
+
+methods {
+    ghost_sum_vote_power_by_id(uint256) returns uint256 envfree
+
+    quorum(uint256) returns uint256
+    proposalVotes(uint256) returns (uint256, uint256, uint256) envfree
+
+    quorumNumerator() returns uint256
+    _executor() returns address
+
+    erc20votes._getPastVotes(address, uint256) returns uint256
+
+    getExecutor() returns address
+
+    timelock() returns address
+}
+
+
+//////////////////////////////////////////////////////////////////////////////
+///////////////////////////////// GHOSTS /////////////////////////////////////
+//////////////////////////////////////////////////////////////////////////////
+
+
+//////////// ghosts to keep track of votes counting ////////////
+
+/*
+ * the sum of voting power of those who voted
+ */
+ghost sum_all_votes_power() returns uint256 {
+	init_state axiom sum_all_votes_power() == 0;
+}
+
+hook Sstore ghost_sum_vote_power_by_id [KEY uint256 pId] uint256 current_power(uint256 old_power) STORAGE {
+	havoc sum_all_votes_power assuming sum_all_votes_power@new() == sum_all_votes_power@old() - old_power + current_power;
+}
+
+/*
+ * sum of all votes casted per proposal
+ */
+ghost tracked_weight(uint256) returns uint256 {
+	init_state axiom forall uint256 p. tracked_weight(p) == 0;
+}
+
+/*
+ * sum of all votes casted
+ */
+ghost sum_tracked_weight() returns uint256 {
+	init_state axiom sum_tracked_weight() == 0;
+}
+
+/*
+ * getter for _proposalVotes.againstVotes
+ */
+ghost votesAgainst() returns uint256 {
+    init_state axiom votesAgainst() == 0;
+}
+
+/*
+ * getter for _proposalVotes.forVotes
+ */
+ghost votesFor() returns uint256 {
+    init_state axiom votesFor() == 0;
+}
+
+/*
+ * getter for _proposalVotes.abstainVotes
+ */
+ghost votesAbstain() returns uint256 {
+    init_state axiom votesAbstain() == 0;
+}
+
+hook Sstore _proposalVotes [KEY uint256 pId].againstVotes uint256 votes(uint256 old_votes) STORAGE {
+	havoc tracked_weight assuming forall uint256 p.(p == pId => tracked_weight@new(p) == tracked_weight@old(p) - old_votes + votes) &&
+	                                            (p != pId => tracked_weight@new(p) == tracked_weight@old(p));
+	havoc sum_tracked_weight assuming sum_tracked_weight@new() == sum_tracked_weight@old() - old_votes + votes;
+    havoc votesAgainst assuming votesAgainst@new() == votesAgainst@old() - old_votes + votes;
+}
+
+hook Sstore _proposalVotes [KEY uint256 pId].forVotes uint256 votes(uint256 old_votes) STORAGE {
+	havoc tracked_weight assuming forall uint256 p.(p == pId => tracked_weight@new(p) == tracked_weight@old(p) - old_votes + votes) &&
+	                                            (p != pId => tracked_weight@new(p) == tracked_weight@old(p));
+	havoc sum_tracked_weight assuming sum_tracked_weight@new() == sum_tracked_weight@old() - old_votes + votes;
+    havoc votesFor assuming votesFor@new() == votesFor@old() - old_votes + votes;
+}
+
+hook Sstore _proposalVotes [KEY uint256 pId].abstainVotes uint256 votes(uint256 old_votes) STORAGE {
+	havoc tracked_weight assuming forall uint256 p.(p == pId => tracked_weight@new(p) == tracked_weight@old(p) - old_votes + votes) &&
+	                                            (p != pId => tracked_weight@new(p) == tracked_weight@old(p));
+	havoc sum_tracked_weight assuming sum_tracked_weight@new() == sum_tracked_weight@old() - old_votes + votes;
+    havoc votesAbstain assuming votesAbstain@new() == votesAbstain@old() - old_votes + votes;
+}
+
+
+//////////////////////////////////////////////////////////////////////////////
+////////////////////////////// INVARIANTS ////////////////////////////////////
+//////////////////////////////////////////////////////////////////////////////
+
+
+
+//////////////////////////////////////////////////////////////////////////////
+///////////////////////////////// RULES //////////////////////////////////////
+//////////////////////////////////////////////////////////////////////////////
+
+
+//NOT FINISHED
+/*
+* the sum of voting power of those who voted is less or equal to the maximum possible votes, per each proposal
+*/
+rule possibleTotalVotes(uint256 pId, uint8 sup, env e, method f) {
+
+    // add requireinvariant  for all i, j. i = i - 1 && i < j => checkpointlookup[i] < checkpointlookup[j];
+    require tracked_weight(pId) <= erc20votes.getPastTotalSupply(e, proposalSnapshot(pId));
+
+    uint256 againstB;
+    uint256 forB;
+    uint256 absatinB;
+    againstB, forB, absatinB = proposalVotes(pId);
+
+    calldataarg args;
+    //f(e, args);
+
+    castVote(e, pId, sup);
+
+    uint256 against;
+    uint256 for;
+    uint256 absatin;
+    against, for, absatin = proposalVotes(pId);
+
+    uint256 ps = proposalSnapshot(pId);
+
+    assert tracked_weight(pId) <= erc20votes.getPastTotalSupply(e, proposalSnapshot(pId)), "bla bla bla";
+}

certora/specs/sanity.spec

@@ -0,0 +1,14 @@
+/*
+This rule looks for a non-reverting execution path to each method, including those overridden in the harness.
+A method has such an execution path if it violates this rule.
+How it works:
+    - If there is a non-reverting execution path, we reach the false assertion, and the sanity fails.
+    - If all execution paths are reverting, we never call the assertion, and the method will pass this rule vacuously.
+*/
+	
+rule sanity(method f) {
+    env e;
+    calldataarg arg;
+    f(e, arg);
+    assert false;
+}

contracts/access/AccessControlEnumerableUpgradeable.sol

@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v4.5.0-rc.0) (access/AccessControlEnumerable.sol)
+
+pragma solidity ^0.8.0;
+
+import "./IAccessControlEnumerableUpgradeable.sol";
+import "./AccessControlUpgradeable.sol";
+import "../utils/structs/EnumerableSetUpgradeable.sol";
+import "../proxy/utils/Initializable.sol";
+
+/**
+ * @dev Extension of {AccessControl} that allows enumerating the members of each role.
+ */
+abstract contract AccessControlEnumerableUpgradeable is Initializable, IAccessControlEnumerableUpgradeable, AccessControlUpgradeable {
+    function __AccessControlEnumerable_init() internal onlyInitializing {
+        __Context_init_unchained();
+        __ERC165_init_unchained();
+        __AccessControl_init_unchained();
+        __AccessControlEnumerable_init_unchained();
+    }
+
+    function __AccessControlEnumerable_init_unchained() internal onlyInitializing {
+    }
+    using EnumerableSetUpgradeable for EnumerableSetUpgradeable.AddressSet;
+
+    mapping(bytes32 => EnumerableSetUpgradeable.AddressSet) private _roleMembers;
+
+    /**
+     * @dev See {IERC165-supportsInterface}.
+     */
+    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
+        return interfaceId == type(IAccessControlEnumerableUpgradeable).interfaceId || super.supportsInterface(interfaceId);
+    }
+
+    /**
+     * @dev Returns one of the accounts that have `role`. `index` must be a
+     * value between 0 and {getRoleMemberCount}, non-inclusive.
+     *
+     * Role bearers are not sorted in any particular way, and their ordering may
+     * change at any point.
+     *
+     * WARNING: When using {getRoleMember} and {getRoleMemberCount}, make sure
+     * you perform all queries on the same block. See the following
+     * https://forum.openzeppelin.com/t/iterating-over-elements-on-enumerableset-in-openzeppelin-contracts/2296[forum post]
+     * for more information.
+     */
+    function getRoleMember(bytes32 role, uint256 index) public view virtual override returns (address) {
+        return _roleMembers[role].at(index);
+    }
+
+    /**
+     * @dev Returns the number of accounts that have `role`. Can be used
+     * together with {getRoleMember} to enumerate all bearers of a role.
+     */
+    function getRoleMemberCount(bytes32 role) public view virtual override returns (uint256) {
+        return _roleMembers[role].length();
+    }
+
+    /**
+     * @dev Overload {_grantRole} to track enumerable memberships
+     */
+    function _grantRole(bytes32 role, address account) internal virtual override {
+        super._grantRole(role, account);
+        _roleMembers[role].add(account);
+    }
+
+    /**
+     * @dev Overload {_revokeRole} to track enumerable memberships
+     */
+    function _revokeRole(bytes32 role, address account) internal virtual override {
+        super._revokeRole(role, account);
+        _roleMembers[role].remove(account);
+    }
+    uint256[49] private __gap;
+}

contracts/access/AccessControlUpgradeable.sol

@@ -0,0 +1,233 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v4.5.0-rc.0) (access/AccessControl.sol)
+
+pragma solidity ^0.8.0;
+
+import "./IAccessControlUpgradeable.sol";
+import "../utils/ContextUpgradeable.sol";
+import "../utils/StringsUpgradeable.sol";
+import "../utils/introspection/ERC165Upgradeable.sol";
+import "../proxy/utils/Initializable.sol";
+
+/**
+ * @dev Contract module that allows children to implement role-based access
+ * control mechanisms. This is a lightweight version that doesn't allow enumerating role
+ * members except through off-chain means by accessing the contract event logs. Some
+ * applications may benefit from on-chain enumerability, for those cases see
+ * {AccessControlEnumerable}.
+ *
+ * Roles are referred to by their `bytes32` identifier. These should be exposed
+ * in the external API and be unique. The best way to achieve this is by
+ * using `public constant` hash digests:
+ *
+ * ```
+ * bytes32 public constant MY_ROLE = keccak256("MY_ROLE");
+ * ```
+ *
+ * Roles can be used to represent a set of permissions. To restrict access to a
+ * function call, use {hasRole}:
+ *
+ * ```
+ * function foo() public {
+ *     require(hasRole(MY_ROLE, msg.sender));
+ *     ...
+ * }
+ * ```
+ *
+ * Roles can be granted and revoked dynamically via the {grantRole} and
+ * {revokeRole} functions. Each role has an associated admin role, and only
+ * accounts that have a role's admin role can call {grantRole} and {revokeRole}.
+ *
+ * By default, the admin role for all roles is `DEFAULT_ADMIN_ROLE`, which means
+ * that only accounts with this role will be able to grant or revoke other
+ * roles. More complex role relationships can be created by using
+ * {_setRoleAdmin}.
+ *
+ * WARNING: The `DEFAULT_ADMIN_ROLE` is also its own admin: it has permission to
+ * grant and revoke this role. Extra precautions should be taken to secure
+ * accounts that have been granted it.
+ */
+abstract contract AccessControlUpgradeable is Initializable, ContextUpgradeable, IAccessControlUpgradeable, ERC165Upgradeable {
+    function __AccessControl_init() internal onlyInitializing {
+        __Context_init_unchained();
+        __ERC165_init_unchained();
+        __AccessControl_init_unchained();
+    }
+
+    function __AccessControl_init_unchained() internal onlyInitializing {
+    }
+    struct RoleData {
+        mapping(address => bool) members;
+        bytes32 adminRole;
+    }
+
+    mapping(bytes32 => RoleData) private _roles;
+
+    bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;
+
+    /**
+     * @dev Modifier that checks that an account has a specific role. Reverts
+     * with a standardized message including the required role.
+     *
+     * The format of the revert reason is given by the following regular expression:
+     *
+     *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
+     *
+     * _Available since v4.1._
+     */
+    modifier onlyRole(bytes32 role) {
+        _checkRole(role, _msgSender());
+        _;
+    }
+
+    /**
+     * @dev See {IERC165-supportsInterface}.
+     */
+    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
+        return interfaceId == type(IAccessControlUpgradeable).interfaceId || super.supportsInterface(interfaceId);
+    }
+
+    /**
+     * @dev Returns `true` if `account` has been granted `role`.
+     */
+    function hasRole(bytes32 role, address account) public view virtual override returns (bool) {
+        return _roles[role].members[account];
+    }
+
+    /**
+     * @dev Revert with a standard message if `account` is missing `role`.
+     *
+     * The format of the revert reason is given by the following regular expression:
+     *
+     *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
+     */
+    function _checkRole(bytes32 role, address account) internal view virtual {
+        if (!hasRole(role, account)) {
+            revert(
+                string(
+                    abi.encodePacked(
+                        "AccessControl: account ",
+                        StringsUpgradeable.toHexString(uint160(account), 20),
+                        " is missing role ",
+                        StringsUpgradeable.toHexString(uint256(role), 32)
+                    )
+                )
+            );
+        }
+    }
+
+    /**
+     * @dev Returns the admin role that controls `role`. See {grantRole} and
+     * {revokeRole}.
+     *
+     * To change a role's admin, use {_setRoleAdmin}.
+     */
+    function getRoleAdmin(bytes32 role) public view virtual override returns (bytes32) {
+        return _roles[role].adminRole;
+    }
+
+    /**
+     * @dev Grants `role` to `account`.
+     *
+     * If `account` had not been already granted `role`, emits a {RoleGranted}
+     * event.
+     *
+     * Requirements:
+     *
+     * - the caller must have ``role``'s admin role.
+     */
+    function grantRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
+        _grantRole(role, account);
+    }
+
+    /**
+     * @dev Revokes `role` from `account`.
+     *
+     * If `account` had been granted `role`, emits a {RoleRevoked} event.
+     *
+     * Requirements:
+     *
+     * - the caller must have ``role``'s admin role.
+     */
+    function revokeRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
+        _revokeRole(role, account);
+    }
+
+    /**
+     * @dev Revokes `role` from the calling account.
+     *
+     * Roles are often managed via {grantRole} and {revokeRole}: this function's
+     * purpose is to provide a mechanism for accounts to lose their privileges
+     * if they are compromised (such as when a trusted device is misplaced).
+     *
+     * If the calling account had been revoked `role`, emits a {RoleRevoked}
+     * event.
+     *
+     * Requirements:
+     *
+     * - the caller must be `account`.
+     */
+    function renounceRole(bytes32 role, address account) public virtual override {
+        require(account == _msgSender(), "AccessControl: can only renounce roles for self");
+
+        _revokeRole(role, account);
+    }
+
+    /**
+     * @dev Grants `role` to `account`.
+     *
+     * If `account` had not been already granted `role`, emits a {RoleGranted}
+     * event. Note that unlike {grantRole}, this function doesn't perform any
+     * checks on the calling account.
+     *
+     * [WARNING]
+     * ====
+     * This function should only be called from the constructor when setting
+     * up the initial roles for the system.
+     *
+     * Using this function in any other way is effectively circumventing the admin
+     * system imposed by {AccessControl}.
+     * ====
+     *
+     * NOTE: This function is deprecated in favor of {_grantRole}.
+     */
+    function _setupRole(bytes32 role, address account) internal virtual {
+        _grantRole(role, account);
+    }
+
+    /**
+     * @dev Sets `adminRole` as ``role``'s admin role.
+     *
+     * Emits a {RoleAdminChanged} event.
+     */
+    function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual {
+        bytes32 previousAdminRole = getRoleAdmin(role);
+        _roles[role].adminRole = adminRole;
+        emit RoleAdminChanged(role, previousAdminRole, adminRole);
+    }
+
+    /**
+     * @dev Grants `role` to `account`.
+     *
+     * Internal function without access restriction.
+     */
+    function _grantRole(bytes32 role, address account) internal virtual {
+        if (!hasRole(role, account)) {
+            _roles[role].members[account] = true;
+            emit RoleGranted(role, account, _msgSender());
+        }
+    }
+
+    /**
+     * @dev Revokes `role` from `account`.
+     *
+     * Internal function without access restriction.
+     */
+    function _revokeRole(bytes32 role, address account) internal virtual {
+        if (hasRole(role, account)) {
+            _roles[role].members[account] = false;
+            emit RoleRevoked(role, account, _msgSender());
+        }
+    }
+    uint256[49] private __gap;
+}

contracts/access/IAccessControlEnumerableUpgradeable.sol

@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (access/IAccessControlEnumerable.sol)
+
+pragma solidity ^0.8.0;
+
+import "./IAccessControlUpgradeable.sol";
+
+/**
+ * @dev External interface of AccessControlEnumerable declared to support ERC165 detection.
+ */
+interface IAccessControlEnumerableUpgradeable is IAccessControlUpgradeable {
+    /**
+     * @dev Returns one of the accounts that have `role`. `index` must be a
+     * value between 0 and {getRoleMemberCount}, non-inclusive.
+     *
+     * Role bearers are not sorted in any particular way, and their ordering may
+     * change at any point.
+     *
+     * WARNING: When using {getRoleMember} and {getRoleMemberCount}, make sure
+     * you perform all queries on the same block. See the following
+     * https://forum.openzeppelin.com/t/iterating-over-elements-on-enumerableset-in-openzeppelin-contracts/2296[forum post]
+     * for more information.
+     */
+    function getRoleMember(bytes32 role, uint256 index) external view returns (address);
+
+    /**
+     * @dev Returns the number of accounts that have `role`. Can be used
+     * together with {getRoleMember} to enumerate all bearers of a role.
+     */
+    function getRoleMemberCount(bytes32 role) external view returns (uint256);
+}

contracts/access/IAccessControlUpgradeable.sol

@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (access/IAccessControl.sol)
+
+pragma solidity ^0.8.0;
+
+/**
+ * @dev External interface of AccessControl declared to support ERC165 detection.
+ */
+interface IAccessControlUpgradeable {
+    /**
+     * @dev Emitted when `newAdminRole` is set as ``role``'s admin role, replacing `previousAdminRole`
+     *
+     * `DEFAULT_ADMIN_ROLE` is the starting admin for all roles, despite
+     * {RoleAdminChanged} not being emitted signaling this.
+     *
+     * _Available since v3.1._
+     */
+    event RoleAdminChanged(bytes32 indexed role, bytes32 indexed previousAdminRole, bytes32 indexed newAdminRole);
+
+    /**
+     * @dev Emitted when `account` is granted `role`.
+     *
+     * `sender` is the account that originated the contract call, an admin role
+     * bearer except when using {AccessControl-_setupRole}.
+     */
+    event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);
+
+    /**
+     * @dev Emitted when `account` is revoked `role`.
+     *
+     * `sender` is the account that originated the contract call:
+     *   - if using `revokeRole`, it is the admin role bearer
+     *   - if using `renounceRole`, it is the role bearer (i.e. `account`)
+     */
+    event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);
+
+    /**
+     * @dev Returns `true` if `account` has been granted `role`.
+     */
+    function hasRole(bytes32 role, address account) external view returns (bool);
+
+    /**
+     * @dev Returns the admin role that controls `role`. See {grantRole} and
+     * {revokeRole}.
+     *
+     * To change a role's admin, use {AccessControl-_setRoleAdmin}.
+     */
+    function getRoleAdmin(bytes32 role) external view returns (bytes32);
+
+    /**
+     * @dev Grants `role` to `account`.
+     *
+     * If `account` had not been already granted `role`, emits a {RoleGranted}
+     * event.
+     *
+     * Requirements:
+     *
+     * - the caller must have ``role``'s admin role.
+     */
+    function grantRole(bytes32 role, address account) external;
+
+    /**
+     * @dev Revokes `role` from `account`.
+     *
+     * If `account` had been granted `role`, emits a {RoleRevoked} event.
+     *
+     * Requirements:
+     *
+     * - the caller must have ``role``'s admin role.
+     */
+    function revokeRole(bytes32 role, address account) external;
+
+    /**
+     * @dev Revokes `role` from the calling account.
+     *
+     * Roles are often managed via {grantRole} and {revokeRole}: this function's
+     * purpose is to provide a mechanism for accounts to lose their privileges
+     * if they are compromised (such as when a trusted device is misplaced).
+     *
+     * If the calling account had been granted `role`, emits a {RoleRevoked}
+     * event.
+     *
+     * Requirements:
+     *
+     * - the caller must be `account`.
+     */
+    function renounceRole(bytes32 role, address account) external;
+}

contracts/access/OwnableUpgradeable.sol

@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (access/Ownable.sol)
+
+pragma solidity ^0.8.0;
+
+import "../utils/ContextUpgradeable.sol";
+import "../proxy/utils/Initializable.sol";
+
+/**
+ * @dev Contract module which provides a basic access control mechanism, where
+ * there is an account (an owner) that can be granted exclusive access to
+ * specific functions.
+ *
+ * By default, the owner account will be the one that deploys the contract. This
+ * can later be changed with {transferOwnership}.
+ *
+ * This module is used through inheritance. It will make available the modifier
+ * `onlyOwner`, which can be applied to your functions to restrict their use to
+ * the owner.
+ */
+abstract contract OwnableUpgradeable is Initializable, ContextUpgradeable {
+    address private _owner;
+
+    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
+
+    /**
+     * @dev Initializes the contract setting the deployer as the initial owner.
+     */
+    function __Ownable_init() internal onlyInitializing {
+        __Context_init_unchained();
+        __Ownable_init_unchained();
+    }
+
+    function __Ownable_init_unchained() internal onlyInitializing {
+        _transferOwnership(_msgSender());
+    }
+
+    /**
+     * @dev Returns the address of the current owner.
+     */
+    function owner() public view virtual returns (address) {
+        return _owner;
+    }
+
+    /**
+     * @dev Throws if called by any account other than the owner.
+     */
+    modifier onlyOwner() {
+        require(owner() == _msgSender(), "Ownable: caller is not the owner");
+        _;
+    }
+
+    /**
+     * @dev Leaves the contract without owner. It will not be possible to call
+     * `onlyOwner` functions anymore. Can only be called by the current owner.
+     *
+     * NOTE: Renouncing ownership will leave the contract without an owner,
+     * thereby removing any functionality that is only available to the owner.
+     */
+    function renounceOwnership() public virtual onlyOwner {
+        _transferOwnership(address(0));
+    }
+
+    /**
+     * @dev Transfers ownership of the contract to a new account (`newOwner`).
+     * Can only be called by the current owner.
+     */
+    function transferOwnership(address newOwner) public virtual onlyOwner {
+        require(newOwner != address(0), "Ownable: new owner is the zero address");
+        _transferOwnership(newOwner);
+    }
+
+    /**
+     * @dev Transfers ownership of the contract to a new account (`newOwner`).
+     * Internal function without access restriction.
+     */
+    function _transferOwnership(address newOwner) internal virtual {
+        address oldOwner = _owner;
+        _owner = newOwner;
+        emit OwnershipTransferred(oldOwner, newOwner);
+    }
+    uint256[49] private __gap;
+}

contracts/access/README.adoc

@@ -0,0 +1,21 @@
+= Access Control
+
+[.readme-notice]
+NOTE: This document is better viewed at https://docs.openzeppelin.com/contracts/api/access
+
+This directory provides ways to restrict who can access the functions of a contract or when they can do it.
+
+- {AccessControl} provides a general role based access control mechanism. Multiple hierarchical roles can be created and assigned each to multiple accounts.
+- {Ownable} is a simpler mechanism with a single owner "role" that can be assigned to a single account. This simpler mechanism can be useful for quick tests but projects with production concerns are likely to outgrow it.
+
+== Authorization
+
+{{Ownable}}
+
+{{IAccessControl}}
+
+{{AccessControl}}
+
+{{IAccessControlEnumerable}}
+
+{{AccessControlEnumerable}}

contracts/finance/PaymentSplitterUpgradeable.sol

@@ -0,0 +1,196 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (finance/PaymentSplitter.sol)
+
+pragma solidity ^0.8.0;
+
+import "../token/ERC20/utils/SafeERC20Upgradeable.sol";
+import "../utils/AddressUpgradeable.sol";
+import "../utils/ContextUpgradeable.sol";
+import "../proxy/utils/Initializable.sol";
+
+/**
+ * @title PaymentSplitter
+ * @dev This contract allows to split Ether payments among a group of accounts. The sender does not need to be aware
+ * that the Ether will be split in this way, since it is handled transparently by the contract.
+ *
+ * The split can be in equal parts or in any other arbitrary proportion. The way this is specified is by assigning each
+ * account to a number of shares. Of all the Ether that this contract receives, each account will then be able to claim
+ * an amount proportional to the percentage of total shares they were assigned.
+ *
+ * `PaymentSplitter` follows a _pull payment_ model. This means that payments are not automatically forwarded to the
+ * accounts but kept in this contract, and the actual transfer is triggered as a separate step by calling the {release}
+ * function.
+ *
+ * NOTE: This contract assumes that ERC20 tokens will behave similarly to native tokens (Ether). Rebasing tokens, and
+ * tokens that apply fees during transfers, are likely to not be supported as expected. If in doubt, we encourage you
+ * to run tests before sending real value to this contract.
+ */
+contract PaymentSplitterUpgradeable is Initializable, ContextUpgradeable {
+    event PayeeAdded(address account, uint256 shares);
+    event PaymentReleased(address to, uint256 amount);
+    event ERC20PaymentReleased(IERC20Upgradeable indexed token, address to, uint256 amount);
+    event PaymentReceived(address from, uint256 amount);
+
+    uint256 private _totalShares;
+    uint256 private _totalReleased;
+
+    mapping(address => uint256) private _shares;
+    mapping(address => uint256) private _released;
+    address[] private _payees;
+
+    mapping(IERC20Upgradeable => uint256) private _erc20TotalReleased;
+    mapping(IERC20Upgradeable => mapping(address => uint256)) private _erc20Released;
+
+    /**
+     * @dev Creates an instance of `PaymentSplitter` where each account in `payees` is assigned the number of shares at
+     * the matching position in the `shares` array.
+     *
+     * All addresses in `payees` must be non-zero. Both arrays must have the same non-zero length, and there must be no
+     * duplicates in `payees`.
+     */
+    function __PaymentSplitter_init(address[] memory payees, uint256[] memory shares_) internal onlyInitializing {
+        __Context_init_unchained();
+        __PaymentSplitter_init_unchained(payees, shares_);
+    }
+
+    function __PaymentSplitter_init_unchained(address[] memory payees, uint256[] memory shares_) internal onlyInitializing {
+        require(payees.length == shares_.length, "PaymentSplitter: payees and shares length mismatch");
+        require(payees.length > 0, "PaymentSplitter: no payees");
+
+        for (uint256 i = 0; i < payees.length; i++) {
+            _addPayee(payees[i], shares_[i]);
+        }
+    }
+
+    /**
+     * @dev The Ether received will be logged with {PaymentReceived} events. Note that these events are not fully
+     * reliable: it's possible for a contract to receive Ether without triggering this function. This only affects the
+     * reliability of the events, and not the actual splitting of Ether.
+     *
+     * To learn more about this see the Solidity documentation for
+     * https://solidity.readthedocs.io/en/latest/contracts.html#fallback-function[fallback
+     * functions].
+     */
+    receive() external payable virtual {
+        emit PaymentReceived(_msgSender(), msg.value);
+    }
+
+    /**
+     * @dev Getter for the total shares held by payees.
+     */
+    function totalShares() public view returns (uint256) {
+        return _totalShares;
+    }
+
+    /**
+     * @dev Getter for the total amount of Ether already released.
+     */
+    function totalReleased() public view returns (uint256) {
+        return _totalReleased;
+    }
+
+    /**
+     * @dev Getter for the total amount of `token` already released. `token` should be the address of an IERC20
+     * contract.
+     */
+    function totalReleased(IERC20Upgradeable token) public view returns (uint256) {
+        return _erc20TotalReleased[token];
+    }
+
+    /**
+     * @dev Getter for the amount of shares held by an account.
+     */
+    function shares(address account) public view returns (uint256) {
+        return _shares[account];
+    }
+
+    /**
+     * @dev Getter for the amount of Ether already released to a payee.
+     */
+    function released(address account) public view returns (uint256) {
+        return _released[account];
+    }
+
+    /**
+     * @dev Getter for the amount of `token` tokens already released to a payee. `token` should be the address of an
+     * IERC20 contract.
+     */
+    function released(IERC20Upgradeable token, address account) public view returns (uint256) {
+        return _erc20Released[token][account];
+    }
+
+    /**
+     * @dev Getter for the address of the payee number `index`.
+     */
+    function payee(uint256 index) public view returns (address) {
+        return _payees[index];
+    }
+
+    /**
+     * @dev Triggers a transfer to `account` of the amount of Ether they are owed, according to their percentage of the
+     * total shares and their previous withdrawals.
+     */
+    function release(address payable account) public virtual {
+        require(_shares[account] > 0, "PaymentSplitter: account has no shares");
+
+        uint256 totalReceived = address(this).balance + totalReleased();
+        uint256 payment = _pendingPayment(account, totalReceived, released(account));
+
+        require(payment != 0, "PaymentSplitter: account is not due payment");
+
+        _released[account] += payment;
+        _totalReleased += payment;
+
+        AddressUpgradeable.sendValue(account, payment);
+        emit PaymentReleased(account, payment);
+    }
+
+    /**
+     * @dev Triggers a transfer to `account` of the amount of `token` tokens they are owed, according to their
+     * percentage of the total shares and their previous withdrawals. `token` must be the address of an IERC20
+     * contract.
+     */
+    function release(IERC20Upgradeable token, address account) public virtual {
+        require(_shares[account] > 0, "PaymentSplitter: account has no shares");
+
+        uint256 totalReceived = token.balanceOf(address(this)) + totalReleased(token);
+        uint256 payment = _pendingPayment(account, totalReceived, released(token, account));
+
+        require(payment != 0, "PaymentSplitter: account is not due payment");
+
+        _erc20Released[token][account] += payment;
+        _erc20TotalReleased[token] += payment;
+
+        SafeERC20Upgradeable.safeTransfer(token, account, payment);
+        emit ERC20PaymentReleased(token, account, payment);
+    }
+
+    /**
+     * @dev internal logic for computing the pending payment of an `account` given the token historical balances and
+     * already released amounts.
+     */
+    function _pendingPayment(
+        address account,
+        uint256 totalReceived,
+        uint256 alreadyReleased
+    ) private view returns (uint256) {
+        return (totalReceived * _shares[account]) / _totalShares - alreadyReleased;
+    }
+
+    /**
+     * @dev Add a new payee to the contract.
+     * @param account The address of the payee to add.
+     * @param shares_ The number of shares owned by the payee.
+     */
+    function _addPayee(address account, uint256 shares_) private {
+        require(account != address(0), "PaymentSplitter: account is the zero address");
+        require(shares_ > 0, "PaymentSplitter: shares are 0");
+        require(_shares[account] == 0, "PaymentSplitter: account already has shares");
+
+        _payees.push(account);
+        _shares[account] = shares_;
+        _totalShares = _totalShares + shares_;
+        emit PayeeAdded(account, shares_);
+    }
+    uint256[43] private __gap;
+}

contracts/finance/README.adoc

@@ -0,0 +1,20 @@
+= Finance
+
+[.readme-notice]
+NOTE: This document is better viewed at https://docs.openzeppelin.com/contracts/api/finance
+
+This directory includes primitives for financial systems:
+
+- {PaymentSplitter} allows to split Ether and ERC20 payments among a group of accounts. The sender does not need to be
+  aware that the assets will be split in this way, since it is handled transparently by the contract. The split can be
+  in equal parts or in any other arbitrary proportion.
+
+- {VestingWallet} handles the vesting of Ether and ERC20 tokens for a given beneficiary. Custody of multiple tokens can
+  be given to this contract, which will release the token to the beneficiary following a given, customizable, vesting
+  schedule.
+
+== Contracts
+
+{{PaymentSplitter}}
+
+{{VestingWallet}}

contracts/finance/VestingWalletUpgradeable.sol

@@ -0,0 +1,146 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (finance/VestingWallet.sol)
+pragma solidity ^0.8.0;
+
+import "../token/ERC20/utils/SafeERC20Upgradeable.sol";
+import "../utils/AddressUpgradeable.sol";
+import "../utils/ContextUpgradeable.sol";
+import "../utils/math/MathUpgradeable.sol";
+import "../proxy/utils/Initializable.sol";
+
+/**
+ * @title VestingWallet
+ * @dev This contract handles the vesting of Eth and ERC20 tokens for a given beneficiary. Custody of multiple tokens
+ * can be given to this contract, which will release the token to the beneficiary following a given vesting schedule.
+ * The vesting schedule is customizable through the {vestedAmount} function.
+ *
+ * Any token transferred to this contract will follow the vesting schedule as if they were locked from the beginning.
+ * Consequently, if the vesting has already started, any amount of tokens sent to this contract will (at least partly)
+ * be immediately releasable.
+ */
+contract VestingWalletUpgradeable is Initializable, ContextUpgradeable {
+    event EtherReleased(uint256 amount);
+    event ERC20Released(address indexed token, uint256 amount);
+
+    uint256 private _released;
+    mapping(address => uint256) private _erc20Released;
+    address private _beneficiary;
+    uint64 private _start;
+    uint64 private _duration;
+
+    /**
+     * @dev Set the beneficiary, start timestamp and vesting duration of the vesting wallet.
+     */
+    function __VestingWallet_init(
+        address beneficiaryAddress,
+        uint64 startTimestamp,
+        uint64 durationSeconds
+    ) internal onlyInitializing {
+        __Context_init_unchained();
+        __VestingWallet_init_unchained(beneficiaryAddress, startTimestamp, durationSeconds);
+    }
+
+    function __VestingWallet_init_unchained(
+        address beneficiaryAddress,
+        uint64 startTimestamp,
+        uint64 durationSeconds
+    ) internal onlyInitializing {
+        require(beneficiaryAddress != address(0), "VestingWallet: beneficiary is zero address");
+        _beneficiary = beneficiaryAddress;
+        _start = startTimestamp;
+        _duration = durationSeconds;
+    }
+
+    /**
+     * @dev The contract should be able to receive Eth.
+     */
+    receive() external payable virtual {}
+
+    /**
+     * @dev Getter for the beneficiary address.
+     */
+    function beneficiary() public view virtual returns (address) {
+        return _beneficiary;
+    }
+
+    /**
+     * @dev Getter for the start timestamp.
+     */
+    function start() public view virtual returns (uint256) {
+        return _start;
+    }
+
+    /**
+     * @dev Getter for the vesting duration.
+     */
+    function duration() public view virtual returns (uint256) {
+        return _duration;
+    }
+
+    /**
+     * @dev Amount of eth already released
+     */
+    function released() public view virtual returns (uint256) {
+        return _released;
+    }
+
+    /**
+     * @dev Amount of token already released
+     */
+    function released(address token) public view virtual returns (uint256) {
+        return _erc20Released[token];
+    }
+
+    /**
+     * @dev Release the native token (ether) that have already vested.
+     *
+     * Emits a {TokensReleased} event.
+     */
+    function release() public virtual {
+        uint256 releasable = vestedAmount(uint64(block.timestamp)) - released();
+        _released += releasable;
+        emit EtherReleased(releasable);
+        AddressUpgradeable.sendValue(payable(beneficiary()), releasable);
+    }
+
+    /**
+     * @dev Release the tokens that have already vested.
+     *
+     * Emits a {TokensReleased} event.
+     */
+    function release(address token) public virtual {
+        uint256 releasable = vestedAmount(token, uint64(block.timestamp)) - released(token);
+        _erc20Released[token] += releasable;
+        emit ERC20Released(token, releasable);
+        SafeERC20Upgradeable.safeTransfer(IERC20Upgradeable(token), beneficiary(), releasable);
+    }
+
+    /**
+     * @dev Calculates the amount of ether that has already vested. Default implementation is a linear vesting curve.
+     */
+    function vestedAmount(uint64 timestamp) public view virtual returns (uint256) {
+        return _vestingSchedule(address(this).balance + released(), timestamp);
+    }
+
+    /**
+     * @dev Calculates the amount of tokens that has already vested. Default implementation is a linear vesting curve.
+     */
+    function vestedAmount(address token, uint64 timestamp) public view virtual returns (uint256) {
+        return _vestingSchedule(IERC20Upgradeable(token).balanceOf(address(this)) + released(token), timestamp);
+    }
+
+    /**
+     * @dev Virtual implementation of the vesting formula. This returns the amout vested, as a function of time, for
+     * an asset given its total historical allocation.
+     */
+    function _vestingSchedule(uint256 totalAllocation, uint64 timestamp) internal view virtual returns (uint256) {
+        if (timestamp < start()) {
+            return 0;
+        } else if (timestamp > start() + duration()) {
+            return totalAllocation;
+        } else {
+            return (totalAllocation * (timestamp - start())) / duration();
+        }
+    }
+    uint256[48] private __gap;
+}

contracts/governance/GovernorUpgradeable.sol

@@ -0,0 +1,394 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v4.5.0-rc.0) (governance/Governor.sol)
+
+pragma solidity ^0.8.0;
+
+import "../utils/cryptography/ECDSAUpgradeable.sol";
+import "../utils/cryptography/draft-EIP712Upgradeable.sol";
+import "../utils/introspection/ERC165Upgradeable.sol";
+import "../utils/math/SafeCastUpgradeable.sol";
+import "../utils/AddressUpgradeable.sol";
+import "../utils/ContextUpgradeable.sol";
+import "../utils/TimersUpgradeable.sol";
+import "./IGovernorUpgradeable.sol";
+import "../proxy/utils/Initializable.sol";
+
+/**
+ * @dev Core of the governance system, designed to be extended though various modules.
+ *
+ * This contract is abstract and requires several function to be implemented in various modules:
+ *
+ * - A counting module must implement {quorum}, {_quorumReached}, {_voteSucceeded} and {_countVote}
+ * - A voting module must implement {getVotes}
+ * - Additionanly, the {votingPeriod} must also be implemented
+ *
+ * _Available since v4.3._
+ */
+abstract contract GovernorUpgradeable is Initializable, ContextUpgradeable, ERC165Upgradeable, EIP712Upgradeable, IGovernorUpgradeable {
+    using SafeCastUpgradeable for uint256;
+    using TimersUpgradeable for TimersUpgradeable.BlockNumber;
+
+    bytes32 public constant BALLOT_TYPEHASH = keccak256("Ballot(uint256 proposalId,uint8 support)");
+
+    struct ProposalCore {
+        TimersUpgradeable.BlockNumber voteStart;
+        TimersUpgradeable.BlockNumber voteEnd;
+        bool executed;
+        bool canceled;
+    }
+
+    string private _name;
+
+    mapping(uint256 => ProposalCore) private _proposals;
+
+    /**
+     * @dev Restrict access to governor executing address. Some module might override the _executor function to make
+     * sure this modifier is consistant with the execution model.
+     */
+    modifier onlyGovernance() {
+        require(_msgSender() == _executor(), "Governor: onlyGovernance");
+        _;
+    }
+
+    /**
+     * @dev Sets the value for {name} and {version}
+     */
+    function __Governor_init(string memory name_) internal onlyInitializing {
+        __Context_init_unchained();
+        __ERC165_init_unchained();
+        __EIP712_init_unchained(name_, version());
+        __IGovernor_init_unchained();
+        __Governor_init_unchained(name_);
+    }
+
+    function __Governor_init_unchained(string memory name_) internal onlyInitializing {
+        _name = name_;
+    }
+
+    /**
+     * @dev Function to receive ETH that will be handled by the governor (disabled if executor is a third party contract)
+     */
+    receive() external payable virtual {
+        require(_executor() == address(this));
+    }
+
+    /**
+     * @dev See {IERC165-supportsInterface}.
+     */
+    function supportsInterface(bytes4 interfaceId) public view virtual override(IERC165Upgradeable, ERC165Upgradeable) returns (bool) {
+        return interfaceId == type(IGovernorUpgradeable).interfaceId || super.supportsInterface(interfaceId);
+    }
+
+    /**
+     * @dev See {IGovernor-name}.
+     */
+    function name() public view virtual override returns (string memory) {
+        return _name;
+    }
+
+    /**
+     * @dev See {IGovernor-version}.
+     */
+    function version() public view virtual override returns (string memory) {
+        return "1";
+    }
+
+    /**
+     * @dev See {IGovernor-hashProposal}.
+     *
+     * The proposal id is produced by hashing the RLC encoded `targets` array, the `values` array, the `calldatas` array
+     * and the descriptionHash (bytes32 which itself is the keccak256 hash of the description string). This proposal id
+     * can be produced from the proposal data which is part of the {ProposalCreated} event. It can even be computed in
+     * advance, before the proposal is submitted.
+     *
+     * Note that the chainId and the governor address are not part of the proposal id computation. Consequently, the
+     * same proposal (with same operation and same description) will have the same id if submitted on multiple governors
+     * accross multiple networks. This also means that in order to execute the same operation twice (on the same
+     * governor) the proposer will have to change the description in order to avoid proposal id conflicts.
+     */
+    function hashProposal(
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        bytes32 descriptionHash
+    ) public pure virtual override returns (uint256) {
+        return uint256(keccak256(abi.encode(targets, values, calldatas, descriptionHash)));
+    }
+
+    /**
+     * @dev See {IGovernor-state}.
+     */
+    function state(uint256 proposalId) public view virtual override returns (ProposalState) {
+        ProposalCore storage proposal = _proposals[proposalId];
+
+        if (proposal.executed) {
+            return ProposalState.Executed;
+        }
+
+        if (proposal.canceled) {
+            return ProposalState.Canceled;
+        }
+
+        uint256 snapshot = proposalSnapshot(proposalId);
+
+        if (snapshot == 0) {
+            revert("Governor: unknown proposal id");
+        }
+
+        if (snapshot >= block.number) {
+            return ProposalState.Pending;
+        }
+
+        uint256 deadline = proposalDeadline(proposalId);
+
+        if (deadline >= block.number) {
+            return ProposalState.Active;
+        }
+
+        if (_quorumReached(proposalId) && _voteSucceeded(proposalId)) {
+            return ProposalState.Succeeded;
+        } else {
+            return ProposalState.Defeated;
+        }
+    }
+
+    /**
+     * @dev See {IGovernor-proposalSnapshot}.
+     */
+    function proposalSnapshot(uint256 proposalId) public view virtual override returns (uint256) {
+        return _proposals[proposalId].voteStart.getDeadline();
+    }
+
+    /**
+     * @dev See {IGovernor-proposalDeadline}.
+     */
+    function proposalDeadline(uint256 proposalId) public view virtual override returns (uint256) {
+        return _proposals[proposalId].voteEnd.getDeadline();
+    }
+
+    /**
+     * @dev Part of the Governor Bravo's interface: _"The number of votes required in order for a voter to become a proposer"_.
+     */
+    function proposalThreshold() public view virtual returns (uint256) {
+        return 0;
+    }
+
+    /**
+     * @dev Amount of votes already cast passes the threshold limit.
+     */
+    function _quorumReached(uint256 proposalId) internal view virtual returns (bool);
+
+    /**
+     * @dev Is the proposal successful or not.
+     */
+    function _voteSucceeded(uint256 proposalId) internal view virtual returns (bool);
+
+    /**
+     * @dev Register a vote with a given support and voting weight.
+     *
+     * Note: Support is generic and can represent various things depending on the voting system used.
+     */
+    function _countVote(
+        uint256 proposalId,
+        address account,
+        uint8 support,
+        uint256 weight
+    ) internal virtual;
+
+    /**
+     * @dev See {IGovernor-propose}.
+     */
+    function propose(
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        string memory description
+    ) public virtual override returns (uint256) {
+        require(
+            getVotes(msg.sender, block.number - 1) >= proposalThreshold(),
+            "GovernorCompatibilityBravo: proposer votes below proposal threshold"
+        );
+
+        uint256 proposalId = hashProposal(targets, values, calldatas, keccak256(bytes(description)));
+
+        require(targets.length == values.length, "Governor: invalid proposal length");
+        require(targets.length == calldatas.length, "Governor: invalid proposal length");
+        require(targets.length > 0, "Governor: empty proposal");
+
+        ProposalCore storage proposal = _proposals[proposalId];
+        require(proposal.voteStart.isUnset(), "Governor: proposal already exists");
+
+        uint64 snapshot = block.number.toUint64() + votingDelay().toUint64();
+        uint64 deadline = snapshot + votingPeriod().toUint64();
+
+        proposal.voteStart.setDeadline(snapshot);
+        proposal.voteEnd.setDeadline(deadline);
+
+        emit ProposalCreated(
+            proposalId,
+            _msgSender(),
+            targets,
+            values,
+            new string[](targets.length),
+            calldatas,
+            snapshot,
+            deadline,
+            description
+        );
+
+        return proposalId;
+    }
+
+    /**
+     * @dev See {IGovernor-execute}.
+     */
+    function execute(
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        bytes32 descriptionHash
+    ) public payable virtual override returns (uint256) {
+        uint256 proposalId = hashProposal(targets, values, calldatas, descriptionHash);
+
+        ProposalState status = state(proposalId);
+        require(
+            status == ProposalState.Succeeded || status == ProposalState.Queued,
+            "Governor: proposal not successful"
+        );
+        _proposals[proposalId].executed = true;
+
+        emit ProposalExecuted(proposalId);
+
+        _execute(proposalId, targets, values, calldatas, descriptionHash);
+
+        return proposalId;
+    }
+
+    /**
+     * @dev Internal execution mechanism. Can be overriden to implement different execution mechanism
+     */
+    function _execute(
+        uint256, /* proposalId */
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        bytes32 /*descriptionHash*/
+    ) internal virtual {
+        string memory errorMessage = "Governor: call reverted without message";
+        for (uint256 i = 0; i < targets.length; ++i) {
+            (bool success, bytes memory returndata) = targets[i].call{value: values[i]}(calldatas[i]);
+            AddressUpgradeable.verifyCallResult(success, returndata, errorMessage);
+        }
+    }
+
+    /**
+     * @dev Internal cancel mechanism: locks up the proposal timer, preventing it from being re-submitted. Marks it as
+     * canceled to allow distinguishing it from executed proposals.
+     *
+     * Emits a {IGovernor-ProposalCanceled} event.
+     */
+    function _cancel(
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        bytes32 descriptionHash
+    ) internal virtual returns (uint256) {
+        uint256 proposalId = hashProposal(targets, values, calldatas, descriptionHash);
+        ProposalState status = state(proposalId);
+
+        require(
+            status != ProposalState.Canceled && status != ProposalState.Expired && status != ProposalState.Executed,
+            "Governor: proposal not active"
+        );
+        _proposals[proposalId].canceled = true;
+
+        emit ProposalCanceled(proposalId);
+
+        return proposalId;
+    }
+
+    /**
+     * @dev See {IGovernor-castVote}.
+     */
+    function castVote(uint256 proposalId, uint8 support) public virtual override returns (uint256) {
+        address voter = _msgSender();
+        return _castVote(proposalId, voter, support, "");
+    }
+
+    /**
+     * @dev See {IGovernor-castVoteWithReason}.
+     */
+    function castVoteWithReason(
+        uint256 proposalId,
+        uint8 support,
+        string calldata reason
+    ) public virtual override returns (uint256) {
+        address voter = _msgSender();
+        return _castVote(proposalId, voter, support, reason);
+    }
+
+    /**
+     * @dev See {IGovernor-castVoteBySig}.
+     */
+    function castVoteBySig(
+        uint256 proposalId,
+        uint8 support,
+        uint8 v,
+        bytes32 r,
+        bytes32 s
+    ) public virtual override returns (uint256) {
+        address voter = ECDSAUpgradeable.recover(
+            _hashTypedDataV4(keccak256(abi.encode(BALLOT_TYPEHASH, proposalId, support))),
+            v,
+            r,
+            s
+        );
+        return _castVote(proposalId, voter, support, "");
+    }
+
+    /**
+     * @dev Internal vote casting mechanism: Check that the vote is pending, that it has not been cast yet, retrieve
+     * voting weight using {IGovernor-getVotes} and call the {_countVote} internal function.
+     *
+     * Emits a {IGovernor-VoteCast} event.
+     */
+    function _castVote(
+        uint256 proposalId,
+        address account,
+        uint8 support,
+        string memory reason
+    ) internal virtual returns (uint256) {
+        ProposalCore storage proposal = _proposals[proposalId];
+        require(state(proposalId) == ProposalState.Active, "Governor: vote not currently active");
+
+        uint256 weight = getVotes(account, proposal.voteStart.getDeadline());
+        _countVote(proposalId, account, support, weight);
+
+        emit VoteCast(account, proposalId, support, weight, reason);
+
+        return weight;
+    }
+
+    /**
+     * @dev Relays a transaction or function call to an arbitrary target. In cases where the governance executor
+     * is some contract other than the governor itself, like when using a timelock, this function can be invoked
+     * in a governance proposal to recover tokens or Ether that was sent to the governor contract by mistake.
+     * Note that if the executor is simply the governor itself, use of `relay` is redundant.
+     */
+    function relay(
+        address target,
+        uint256 value,
+        bytes calldata data
+    ) external virtual onlyGovernance {
+        AddressUpgradeable.functionCallWithValue(target, data, value);
+    }
+
+    /**
+     * @dev Address through which the governor executes action. Will be overloaded by module that execute actions
+     * through another contract such as a timelock.
+     */
+    function _executor() internal view virtual returns (address) {
+        return address(this);
+    }
+    uint256[48] private __gap;
+}

contracts/governance/IGovernorUpgradeable.sol

@@ -0,0 +1,226 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v4.5.0-rc.0) (governance/IGovernor.sol)
+
+pragma solidity ^0.8.0;
+
+import "../utils/introspection/ERC165Upgradeable.sol";
+import "../proxy/utils/Initializable.sol";
+
+/**
+ * @dev Interface of the {Governor} core.
+ *
+ * _Available since v4.3._
+ */
+abstract contract IGovernorUpgradeable is Initializable, IERC165Upgradeable {
+    function __IGovernor_init() internal onlyInitializing {
+        __IGovernor_init_unchained();
+    }
+
+    function __IGovernor_init_unchained() internal onlyInitializing {
+    }
+    enum ProposalState {
+        Pending,
+        Active,
+        Canceled,
+        Defeated,
+        Succeeded,
+        Queued,
+        Expired,
+        Executed
+    }
+
+    /**
+     * @dev Emitted when a proposal is created.
+     */
+    event ProposalCreated(
+        uint256 proposalId,
+        address proposer,
+        address[] targets,
+        uint256[] values,
+        string[] signatures,
+        bytes[] calldatas,
+        uint256 startBlock,
+        uint256 endBlock,
+        string description
+    );
+
+    /**
+     * @dev Emitted when a proposal is canceled.
+     */
+    event ProposalCanceled(uint256 proposalId);
+
+    /**
+     * @dev Emitted when a proposal is executed.
+     */
+    event ProposalExecuted(uint256 proposalId);
+
+    /**
+     * @dev Emitted when a vote is cast.
+     *
+     * Note: `support` values should be seen as buckets. There interpretation depends on the voting module used.
+     */
+    event VoteCast(address indexed voter, uint256 proposalId, uint8 support, uint256 weight, string reason);
+
+    /**
+     * @notice module:core
+     * @dev Name of the governor instance (used in building the ERC712 domain separator).
+     */
+    function name() public view virtual returns (string memory);
+
+    /**
+     * @notice module:core
+     * @dev Version of the governor instance (used in building the ERC712 domain separator). Default: "1"
+     */
+    function version() public view virtual returns (string memory);
+
+    /**
+     * @notice module:voting
+     * @dev A description of the possible `support` values for {castVote} and the way these votes are counted, meant to
+     * be consumed by UIs to show correct vote options and interpret the results. The string is a URL-encoded sequence of
+     * key-value pairs that each describe one aspect, for example `support=bravo&quorum=for,abstain`.
+     *
+     * There are 2 standard keys: `support` and `quorum`.
+     *
+     * - `support=bravo` refers to the vote options 0 = Against, 1 = For, 2 = Abstain, as in `GovernorBravo`.
+     * - `quorum=bravo` means that only For votes are counted towards quorum.
+     * - `quorum=for,abstain` means that both For and Abstain votes are counted towards quorum.
+     *
+     * NOTE: The string can be decoded by the standard
+     * https://developer.mozilla.org/en-US/docs/Web/API/URLSearchParams[`URLSearchParams`]
+     * JavaScript class.
+     */
+    // solhint-disable-next-line func-name-mixedcase
+    function COUNTING_MODE() public pure virtual returns (string memory);
+
+    /**
+     * @notice module:core
+     * @dev Hashing function used to (re)build the proposal id from the proposal details..
+     */
+    function hashProposal(
+        address[] calldata targets,
+        uint256[] calldata values,
+        bytes[] calldata calldatas,
+        bytes32 descriptionHash
+    ) public pure virtual returns (uint256);
+
+    /**
+     * @notice module:core
+     * @dev Current state of a proposal, following Compound's convention
+     */
+    function state(uint256 proposalId) public view virtual returns (ProposalState);
+
+    /**
+     * @notice module:core
+     * @dev Block number used to retrieve user's votes and quorum. As per Compound's Comp and OpenZeppelin's
+     * ERC20Votes, the snapshot is performed at the end of this block. Hence, voting for this proposal starts at the
+     * beginning of the following block.
+     */
+    function proposalSnapshot(uint256 proposalId) public view virtual returns (uint256);
+
+    /**
+     * @notice module:core
+     * @dev Block number at which votes close. Votes close at the end of this block, so it is possible to cast a vote
+     * during this block.
+     */
+    function proposalDeadline(uint256 proposalId) public view virtual returns (uint256);
+
+    /**
+     * @notice module:user-config
+     * @dev Delay, in number of block, between the proposal is created and the vote starts. This can be increassed to
+     * leave time for users to buy voting power, of delegate it, before the voting of a proposal starts.
+     */
+    function votingDelay() public view virtual returns (uint256);
+
+    /**
+     * @notice module:user-config
+     * @dev Delay, in number of blocks, between the vote start and vote ends.
+     *
+     * NOTE: The {votingDelay} can delay the start of the vote. This must be considered when setting the voting
+     * duration compared to the voting delay.
+     */
+    function votingPeriod() public view virtual returns (uint256);
+
+    /**
+     * @notice module:user-config
+     * @dev Minimum number of cast voted required for a proposal to be successful.
+     *
+     * Note: The `blockNumber` parameter corresponds to the snaphot used for counting vote. This allows to scale the
+     * quroum depending on values such as the totalSupply of a token at this block (see {ERC20Votes}).
+     */
+    function quorum(uint256 blockNumber) public view virtual returns (uint256);
+
+    /**
+     * @notice module:reputation
+     * @dev Voting power of an `account` at a specific `blockNumber`.
+     *
+     * Note: this can be implemented in a number of ways, for example by reading the delegated balance from one (or
+     * multiple), {ERC20Votes} tokens.
+     */
+    function getVotes(address account, uint256 blockNumber) public view virtual returns (uint256);
+
+    /**
+     * @notice module:voting
+     * @dev Returns weither `account` has cast a vote on `proposalId`.
+     */
+    function hasVoted(uint256 proposalId, address account) public view virtual returns (bool);
+
+    /**
+     * @dev Create a new proposal. Vote start {IGovernor-votingDelay} blocks after the proposal is created and ends
+     * {IGovernor-votingPeriod} blocks after the voting starts.
+     *
+     * Emits a {ProposalCreated} event.
+     */
+    function propose(
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        string memory description
+    ) public virtual returns (uint256 proposalId);
+
+    /**
+     * @dev Execute a successful proposal. This requires the quorum to be reached, the vote to be successful, and the
+     * deadline to be reached.
+     *
+     * Emits a {ProposalExecuted} event.
+     *
+     * Note: some module can modify the requirements for execution, for example by adding an additional timelock.
+     */
+    function execute(
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        bytes32 descriptionHash
+    ) public payable virtual returns (uint256 proposalId);
+
+    /**
+     * @dev Cast a vote
+     *
+     * Emits a {VoteCast} event.
+     */
+    function castVote(uint256 proposalId, uint8 support) public virtual returns (uint256 balance);
+
+    /**
+     * @dev Cast a vote with a reason
+     *
+     * Emits a {VoteCast} event.
+     */
+    function castVoteWithReason(
+        uint256 proposalId,
+        uint8 support,
+        string calldata reason
+    ) public virtual returns (uint256 balance);
+
+    /**
+     * @dev Cast a vote using the user cryptographic signature.
+     *
+     * Emits a {VoteCast} event.
+     */
+    function castVoteBySig(
+        uint256 proposalId,
+        uint8 support,
+        uint8 v,
+        bytes32 r,
+        bytes32 s
+    ) public virtual returns (uint256 balance);
+    uint256[50] private __gap;
+}

contracts/governance/README.adoc

@@ -0,0 +1,176 @@
+= Governance
+
+[.readme-notice]
+NOTE: This document is better viewed at https://docs.openzeppelin.com/contracts/api/governance
+
+This directory includes primitives for on-chain governance.
+
+== Governor
+
+This modular system of Governor contracts allows the deployment on-chain voting protocols similar to https://compound.finance/docs/governance[Compound's Governor Alpha & Bravo] and beyond, through the ability to easily customize multiple aspects of the protocol.
+
+[TIP]
+====
+For a guided experience, set up your Governor contract using https://wizard.openzeppelin.com/#governor[Contracts Wizard].
+
+For a written walkthrough, check out our guide on xref:ROOT:governance.adoc[How to set up on-chain governance].
+====
+
+* {Governor}: The core contract that contains all the logic and primitives. It is abstract and requires choosing one of each of the modules below, or custom ones.
+
+Votes modules determine the source of voting power, and sometimes quorum number.
+
+* {GovernorVotes}: Extracts voting weight from an {ERC20Votes} token.
+
+* {GovernorVotesComp}: Extracts voting weight from a COMP-like or {ERC20VotesComp} token.
+
+* {GovernorVotesQuorumFraction}: Combines with `GovernorVotes` to set the quorum as a fraction of the total token supply.
+
+Counting modules determine valid voting options.
+
+* {GovernorCountingSimple}: Simple voting mechanism with 3 voting options: Against, For and Abstain.
+
+Timelock extensions add a delay for governance decisions to be executed. The workflow is extended to require a `queue` step before execution. With these modules, proposals are executed by the external timelock contract, thus it is the timelock that has to hold the assets that are being governed.
+
+* {GovernorTimelockControl}: Connects with an instance of {TimelockController}. Allows multiple proposers and executors, in addition to the Governor itself.
+
+* {GovernorTimelockCompound}: Connects with an instance of Compound's https://github.com/compound-finance/compound-protocol/blob/master/contracts/Timelock.sol[`Timelock`] contract.
+
+Other extensions can customize the behavior or interface in multiple ways.
+
+* {GovernorCompatibilityBravo}: Extends the interface to be fully `GovernorBravo`-compatible. Note that events are compatible regardless of whether this extension is included or not.
+
+* {GovernorSettings}: Manages some of the settings (voting delay, voting period duration, and proposal threshold) in a way that can be updated through a governance proposal, without requiering an upgrade.
+
+* {GovernorPreventLateQuorum}: Ensures there is a minimum voting period after quorum is reached as a security protection against large voters.
+
+In addition to modules and extensions, the core contract requires a few virtual functions to be implemented to your particular specifications:
+
+* <<Governor-votingDelay-,`votingDelay()`>>: Delay (in number of blocks) since the proposal is submitted until voting power is fixed and voting starts. This can be used to enforce a delay after a proposal is published for users to buy tokens, or delegate their votes.
+* <<Governor-votingPeriod-,`votingPeriod()`>>: Delay (in number of blocks) since the proposal starts until voting ends.
+* <<Governor-quorum-uint256-,`quorum(uint256 blockNumber)`>>: Quorum required for a proposal to be successful. This function includes a `blockNumber` argument so the quorum can adapt through time, for example, to follow a token's `totalSupply`.
+
+NOTE: Functions of the `Governor` contract do not include access control. If you want to restrict access, you should add these checks by overloading the particular functions. Among these, {Governor-_cancel} is internal by default, and you will have to expose it (with the right access control mechanism) yourself if this function is needed.
+
+=== Core
+
+{{IGovernor}}
+
+{{Governor}}
+
+=== Modules
+
+{{GovernorCountingSimple}}
+
+{{GovernorVotes}}
+
+{{GovernorVotesQuorumFraction}}
+
+{{GovernorVotesComp}}
+
+=== Extensions
+
+{{GovernorTimelockControl}}
+
+{{GovernorTimelockCompound}}
+
+{{GovernorSettings}}
+
+{{GovernorPreventLateQuorum}}
+
+{{GovernorCompatibilityBravo}}
+
+=== Deprecated
+
+{{GovernorProposalThreshold}}
+
+== Utils
+
+{{Votes}}
+
+== Timelock
+
+In a governance system, the {TimelockController} contract is in charge of introducing a delay between a proposal and its execution. It can be used with or without a {Governor}.
+
+{{TimelockController}}
+
+[[timelock-terminology]]
+==== Terminology
+
+* *Operation:* A transaction (or a set of transactions) that is the subject of the timelock. It has to be scheduled by a proposer and executed by an executor. The timelock enforces a minimum delay between the proposition and the execution (see xref:access-control.adoc#operation_lifecycle[operation lifecycle]). If the operation contains multiple transactions (batch mode), they are executed atomically. Operations are identified by the hash of their content.
+* *Operation status:*
+** *Unset:* An operation that is not part of the timelock mechanism.
+** *Pending:* An operation that has been scheduled, before the timer expires.
+** *Ready:* An operation that has been scheduled, after the timer expires.
+** *Done:* An operation that has been executed.
+* *Predecessor*: An (optional) dependency between operations. An operation can depend on another operation (its predecessor), forcing the execution order of these two operations.
+* *Role*:
+** *Admin:* An address (smart contract or EOA) that is in charge of granting the roles of Proposer and Executor.
+** *Proposer:* An address (smart contract or EOA) that is in charge of scheduling (and cancelling) operations.
+** *Executor:* An address (smart contract or EOA) that is in charge of executing operations once the timelock has expired. This role can be given to the zero address to allow anyone to execute operations.
+
+[[timelock-operation]]
+==== Operation structure
+
+Operation executed by the xref:api:governance.adoc#TimelockController[`TimelockController`] can contain one or multiple subsequent calls. Depending on whether you need to multiple calls to be executed atomically, you can either use simple or batched operations.
+
+Both operations contain:
+
+* *Target*, the address of the smart contract that the timelock should operate on.
+* *Value*, in wei, that should be sent with the transaction. Most of the time this will be 0. Ether can be deposited before-end or passed along when executing the transaction.
+* *Data*, containing the encoded function selector and parameters of the call. This can be produced using a number of tools. For example, a maintenance operation granting role `ROLE` to `ACCOUNT` can be encode using web3js as follows:
+
+```javascript
+const data = timelock.contract.methods.grantRole(ROLE, ACCOUNT).encodeABI()
+```
+
+* *Predecessor*, that specifies a dependency between operations. This dependency is optional. Use `bytes32(0)` if the operation does not have any dependency.
+* *Salt*, used to disambiguate two otherwise identical operations. This can be any random value.
+
+In the case of batched operations, `target`, `value` and `data` are specified as arrays, which must be of the same length.
+
+[[timelock-operation-lifecycle]]
+==== Operation lifecycle
+
+Timelocked operations are identified by a unique id (their hash) and follow a specific lifecycle:
+
+`Unset` -> `Pending` -> `Pending` + `Ready` -> `Done`
+
+* By calling xref:api:governance.adoc#TimelockController-schedule-address-uint256-bytes-bytes32-bytes32-uint256-[`schedule`] (or xref:api:governance.adoc#TimelockController-scheduleBatch-address---uint256---bytes---bytes32-bytes32-uint256-[`scheduleBatch`]), a proposer moves the operation from the `Unset` to the `Pending` state. This starts a timer that must be longer than the minimum delay. The timer expires at a timestamp accessible through the xref:api:governance.adoc#TimelockController-getTimestamp-bytes32-[`getTimestamp`] method.
+* Once the timer expires, the operation automatically gets the `Ready` state. At this point, it can be executed.
+* By calling xref:api:governance.adoc#TimelockController-TimelockController-execute-address-uint256-bytes-bytes32-bytes32-[`execute`] (or xref:api:governance.adoc#TimelockController-executeBatch-address---uint256---bytes---bytes32-bytes32-[`executeBatch`]), an executor triggers the operation's underlying transactions and moves it to the `Done` state. If the operation has a predecessor, it has to be in the `Done` state for this transition to succeed.
+* xref:api:governance.adoc#TimelockController-TimelockController-cancel-bytes32-[`cancel`] allows proposers to cancel any `Pending` operation. This resets the operation to the `Unset` state. It is thus possible for a proposer to re-schedule an operation that has been cancelled. In this case, the timer restarts when the operation is re-scheduled.
+
+Operations status can be queried using the functions:
+
+* xref:api:governance.adoc#TimelockController-isOperationPending-bytes32-[`isOperationPending(bytes32)`]
+* xref:api:governance.adoc#TimelockController-isOperationReady-bytes32-[`isOperationReady(bytes32)`]
+* xref:api:governance.adoc#TimelockController-isOperationDone-bytes32-[`isOperationDone(bytes32)`]
+
+[[timelock-roles]]
+==== Roles
+
+[[timelock-admin]]
+===== Admin
+
+The admins are in charge of managing proposers and executors. For the timelock to be self-governed, this role should only be given to the timelock itself. Upon deployment, both the timelock and the deployer have this role. After further configuration and testing, the deployer can renounce this role such that all further maintenance operations have to go through the timelock process.
+
+This role is identified by the *TIMELOCK_ADMIN_ROLE* value: `0x5f58e3a2316349923ce3780f8d587db2d72378aed66a8261c916544fa6846ca5`
+
+[[timelock-proposer]]
+===== Proposer
+
+The proposers are in charge of scheduling (and cancelling) operations. This is a critical role, that should be given to governing entities. This could be an EOA, a multisig, or a DAO.
+
+WARNING: *Proposer fight:* Having multiple proposers, while providing redundancy in case one becomes unavailable, can be dangerous. As proposer have their say on all operations, they could cancel operations they disagree with, including operations to remove them for the proposers.
+
+This role is identified by the *PROPOSER_ROLE* value: `0xb09aa5aeb3702cfd50b6b62bc4532604938f21248a27a1d5ca736082b6819cc1`
+
+[[timelock-executor]]
+===== Executor
+
+The executors are in charge of executing the operations scheduled by the proposers once the timelock expires. Logic dictates that multisig or DAO that are proposers should also be executors in order to guarantee operations that have been scheduled will eventually be executed. However, having additional executors can reduce the cost (the executing transaction does not require validation by the multisig or DAO that proposed it), while ensuring whoever is in charge of execution cannot trigger actions that have not been scheduled by the proposers. Alternatively, it is possible to allow _any_ address to execute a proposal once the timelock has expired by granting the executor role to the zero address.
+
+This role is identified by the *EXECUTOR_ROLE* value: `0xd8aa0f3194971a2a116679f7c2090f6939c8d4e01a2a8d7e41d55e5351469e63`
+
+WARNING: A live contract without at least one proposer and one executor is locked. Make sure these roles are filled by reliable entities before the deployer renounces its administrative rights in favour of the timelock contract itself. See the {AccessControl} documentation to learn more about role management.

contracts/governance/TimelockControllerUpgradeable.sol

@@ -0,0 +1,366 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (governance/TimelockController.sol)
+
+pragma solidity ^0.8.0;
+
+import "../access/AccessControlUpgradeable.sol";
+import "../proxy/utils/Initializable.sol";
+
+/**
+ * @dev Contract module which acts as a timelocked controller. When set as the
+ * owner of an `Ownable` smart contract, it enforces a timelock on all
+ * `onlyOwner` maintenance operations. This gives time for users of the
+ * controlled contract to exit before a potentially dangerous maintenance
+ * operation is applied.
+ *
+ * By default, this contract is self administered, meaning administration tasks
+ * have to go through the timelock process. The proposer (resp executor) role
+ * is in charge of proposing (resp executing) operations. A common use case is
+ * to position this {TimelockController} as the owner of a smart contract, with
+ * a multisig or a DAO as the sole proposer.
+ *
+ * _Available since v3.3._
+ */
+contract TimelockControllerUpgradeable is Initializable, AccessControlUpgradeable {
+    bytes32 public constant TIMELOCK_ADMIN_ROLE = keccak256("TIMELOCK_ADMIN_ROLE");
+    bytes32 public constant PROPOSER_ROLE = keccak256("PROPOSER_ROLE");
+    bytes32 public constant EXECUTOR_ROLE = keccak256("EXECUTOR_ROLE");
+    uint256 internal constant _DONE_TIMESTAMP = uint256(1);
+
+    mapping(bytes32 => uint256) private _timestamps;
+    uint256 private _minDelay;
+
+    /**
+     * @dev Emitted when a call is scheduled as part of operation `id`.
+     */
+    event CallScheduled(
+        bytes32 indexed id,
+        uint256 indexed index,
+        address target,
+        uint256 value,
+        bytes data,
+        bytes32 predecessor,
+        uint256 delay
+    );
+
+    /**
+     * @dev Emitted when a call is performed as part of operation `id`.
+     */
+    event CallExecuted(bytes32 indexed id, uint256 indexed index, address target, uint256 value, bytes data);
+
+    /**
+     * @dev Emitted when operation `id` is cancelled.
+     */
+    event Cancelled(bytes32 indexed id);
+
+    /**
+     * @dev Emitted when the minimum delay for future operations is modified.
+     */
+    event MinDelayChange(uint256 oldDuration, uint256 newDuration);
+
+    /**
+     * @dev Initializes the contract with a given `minDelay`.
+     */
+    function __TimelockController_init(
+        uint256 minDelay,
+        address[] memory proposers,
+        address[] memory executors
+    ) internal onlyInitializing {
+        __Context_init_unchained();
+        __ERC165_init_unchained();
+        __AccessControl_init_unchained();
+        __TimelockController_init_unchained(minDelay, proposers, executors);
+    }
+
+    function __TimelockController_init_unchained(
+        uint256 minDelay,
+        address[] memory proposers,
+        address[] memory executors
+    ) internal onlyInitializing {
+        _setRoleAdmin(TIMELOCK_ADMIN_ROLE, TIMELOCK_ADMIN_ROLE);
+        _setRoleAdmin(PROPOSER_ROLE, TIMELOCK_ADMIN_ROLE);
+        _setRoleAdmin(EXECUTOR_ROLE, TIMELOCK_ADMIN_ROLE);
+
+        // deployer + self administration
+        _setupRole(TIMELOCK_ADMIN_ROLE, _msgSender());
+        _setupRole(TIMELOCK_ADMIN_ROLE, address(this));
+
+        // register proposers
+        for (uint256 i = 0; i < proposers.length; ++i) {
+            _setupRole(PROPOSER_ROLE, proposers[i]);
+        }
+
+        // register executors
+        for (uint256 i = 0; i < executors.length; ++i) {
+            _setupRole(EXECUTOR_ROLE, executors[i]);
+        }
+
+        _minDelay = minDelay;
+        emit MinDelayChange(0, minDelay);
+    }
+
+    /**
+     * @dev Modifier to make a function callable only by a certain role. In
+     * addition to checking the sender's role, `address(0)` 's role is also
+     * considered. Granting a role to `address(0)` is equivalent to enabling
+     * this role for everyone.
+     */
+    modifier onlyRoleOrOpenRole(bytes32 role) {
+        if (!hasRole(role, address(0))) {
+            _checkRole(role, _msgSender());
+        }
+        _;
+    }
+
+    /**
+     * @dev Contract might receive/hold ETH as part of the maintenance process.
+     */
+    receive() external payable {}
+
+    /**
+     * @dev Returns whether an id correspond to a registered operation. This
+     * includes both Pending, Ready and Done operations.
+     */
+    function isOperation(bytes32 id) public view virtual returns (bool pending) {
+        return getTimestamp(id) > 0;
+    }
+
+    /**
+     * @dev Returns whether an operation is pending or not.
+     */
+    function isOperationPending(bytes32 id) public view virtual returns (bool pending) {
+        return getTimestamp(id) > _DONE_TIMESTAMP;
+    }
+
+    /**
+     * @dev Returns whether an operation is ready or not.
+     */
+    function isOperationReady(bytes32 id) public view virtual returns (bool ready) {
+        uint256 timestamp = getTimestamp(id);
+        return timestamp > _DONE_TIMESTAMP && timestamp <= block.timestamp;
+    }
+
+    /**
+     * @dev Returns whether an operation is done or not.
+     */
+    function isOperationDone(bytes32 id) public view virtual returns (bool done) {
+        return getTimestamp(id) == _DONE_TIMESTAMP;
+    }
+
+    /**
+     * @dev Returns the timestamp at with an operation becomes ready (0 for
+     * unset operations, 1 for done operations).
+     */
+    function getTimestamp(bytes32 id) public view virtual returns (uint256 timestamp) {
+        return _timestamps[id];
+    }
+
+    /**
+     * @dev Returns the minimum delay for an operation to become valid.
+     *
+     * This value can be changed by executing an operation that calls `updateDelay`.
+     */
+    function getMinDelay() public view virtual returns (uint256 duration) {
+        return _minDelay;
+    }
+
+    /**
+     * @dev Returns the identifier of an operation containing a single
+     * transaction.
+     */
+    function hashOperation(
+        address target,
+        uint256 value,
+        bytes calldata data,
+        bytes32 predecessor,
+        bytes32 salt
+    ) public pure virtual returns (bytes32 hash) {
+        return keccak256(abi.encode(target, value, data, predecessor, salt));
+    }
+
+    /**
+     * @dev Returns the identifier of an operation containing a batch of
+     * transactions.
+     */
+    function hashOperationBatch(
+        address[] calldata targets,
+        uint256[] calldata values,
+        bytes[] calldata datas,
+        bytes32 predecessor,
+        bytes32 salt
+    ) public pure virtual returns (bytes32 hash) {
+        return keccak256(abi.encode(targets, values, datas, predecessor, salt));
+    }
+
+    /**
+     * @dev Schedule an operation containing a single transaction.
+     *
+     * Emits a {CallScheduled} event.
+     *
+     * Requirements:
+     *
+     * - the caller must have the 'proposer' role.
+     */
+    function schedule(
+        address target,
+        uint256 value,
+        bytes calldata data,
+        bytes32 predecessor,
+        bytes32 salt,
+        uint256 delay
+    ) public virtual onlyRole(PROPOSER_ROLE) {
+        bytes32 id = hashOperation(target, value, data, predecessor, salt);
+        _schedule(id, delay);
+        emit CallScheduled(id, 0, target, value, data, predecessor, delay);
+    }
+
+    /**
+     * @dev Schedule an operation containing a batch of transactions.
+     *
+     * Emits one {CallScheduled} event per transaction in the batch.
+     *
+     * Requirements:
+     *
+     * - the caller must have the 'proposer' role.
+     */
+    function scheduleBatch(
+        address[] calldata targets,
+        uint256[] calldata values,
+        bytes[] calldata datas,
+        bytes32 predecessor,
+        bytes32 salt,
+        uint256 delay
+    ) public virtual onlyRole(PROPOSER_ROLE) {
+        require(targets.length == values.length, "TimelockController: length mismatch");
+        require(targets.length == datas.length, "TimelockController: length mismatch");
+
+        bytes32 id = hashOperationBatch(targets, values, datas, predecessor, salt);
+        _schedule(id, delay);
+        for (uint256 i = 0; i < targets.length; ++i) {
+            emit CallScheduled(id, i, targets[i], values[i], datas[i], predecessor, delay);
+        }
+    }
+
+    /**
+     * @dev Schedule an operation that is to becomes valid after a given delay.
+     */
+    function _schedule(bytes32 id, uint256 delay) private {
+        require(!isOperation(id), "TimelockController: operation already scheduled");
+        require(delay >= getMinDelay(), "TimelockController: insufficient delay");
+        _timestamps[id] = block.timestamp + delay;
+    }
+
+    /**
+     * @dev Cancel an operation.
+     *
+     * Requirements:
+     *
+     * - the caller must have the 'proposer' role.
+     */
+    function cancel(bytes32 id) public virtual onlyRole(PROPOSER_ROLE) {
+        require(isOperationPending(id), "TimelockController: operation cannot be cancelled");
+        delete _timestamps[id];
+
+        emit Cancelled(id);
+    }
+
+    /**
+     * @dev Execute an (ready) operation containing a single transaction.
+     *
+     * Emits a {CallExecuted} event.
+     *
+     * Requirements:
+     *
+     * - the caller must have the 'executor' role.
+     */
+    function execute(
+        address target,
+        uint256 value,
+        bytes calldata data,
+        bytes32 predecessor,
+        bytes32 salt
+    ) public payable virtual onlyRoleOrOpenRole(EXECUTOR_ROLE) {
+        bytes32 id = hashOperation(target, value, data, predecessor, salt);
+        _beforeCall(id, predecessor);
+        _call(id, 0, target, value, data);
+        _afterCall(id);
+    }
+
+    /**
+     * @dev Execute an (ready) operation containing a batch of transactions.
+     *
+     * Emits one {CallExecuted} event per transaction in the batch.
+     *
+     * Requirements:
+     *
+     * - the caller must have the 'executor' role.
+     */
+    function executeBatch(
+        address[] calldata targets,
+        uint256[] calldata values,
+        bytes[] calldata datas,
+        bytes32 predecessor,
+        bytes32 salt
+    ) public payable virtual onlyRoleOrOpenRole(EXECUTOR_ROLE) {
+        require(targets.length == values.length, "TimelockController: length mismatch");
+        require(targets.length == datas.length, "TimelockController: length mismatch");
+
+        bytes32 id = hashOperationBatch(targets, values, datas, predecessor, salt);
+        _beforeCall(id, predecessor);
+        for (uint256 i = 0; i < targets.length; ++i) {
+            _call(id, i, targets[i], values[i], datas[i]);
+        }
+        _afterCall(id);
+    }
+
+    /**
+     * @dev Checks before execution of an operation's calls.
+     */
+    function _beforeCall(bytes32 id, bytes32 predecessor) private view {
+        require(isOperationReady(id), "TimelockController: operation is not ready");
+        require(predecessor == bytes32(0) || isOperationDone(predecessor), "TimelockController: missing dependency");
+    }
+
+    /**
+     * @dev Checks after execution of an operation's calls.
+     */
+    function _afterCall(bytes32 id) private {
+        require(isOperationReady(id), "TimelockController: operation is not ready");
+        _timestamps[id] = _DONE_TIMESTAMP;
+    }
+
+    /**
+     * @dev Execute an operation's call.
+     *
+     * Emits a {CallExecuted} event.
+     */
+    function _call(
+        bytes32 id,
+        uint256 index,
+        address target,
+        uint256 value,
+        bytes calldata data
+    ) private {
+        (bool success, ) = target.call{value: value}(data);
+        require(success, "TimelockController: underlying transaction reverted");
+
+        emit CallExecuted(id, index, target, value, data);
+    }
+
+    /**
+     * @dev Changes the minimum timelock duration for future operations.
+     *
+     * Emits a {MinDelayChange} event.
+     *
+     * Requirements:
+     *
+     * - the caller must be the timelock itself. This can only be achieved by scheduling and later executing
+     * an operation where the timelock is the target and the data is the ABI-encoded call to this function.
+     */
+    function updateDelay(uint256 newDelay) external virtual {
+        require(msg.sender == address(this), "TimelockController: caller must be timelock");
+        emit MinDelayChange(_minDelay, newDelay);
+        _minDelay = newDelay;
+    }
+    uint256[48] private __gap;
+}

contracts/governance/compatibility/GovernorCompatibilityBravoUpgradeable.sol

@@ -0,0 +1,301 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v4.5.0-rc.0) (governance/compatibility/GovernorCompatibilityBravo.sol)
+
+pragma solidity ^0.8.0;
+
+import "../../utils/CountersUpgradeable.sol";
+import "../../utils/math/SafeCastUpgradeable.sol";
+import "../extensions/IGovernorTimelockUpgradeable.sol";
+import "../GovernorUpgradeable.sol";
+import "./IGovernorCompatibilityBravoUpgradeable.sol";
+import "../../proxy/utils/Initializable.sol";
+
+/**
+ * @dev Compatibility layer that implements GovernorBravo compatibility on to of {Governor}.
+ *
+ * This compatibility layer includes a voting system and requires a {IGovernorTimelock} compatible module to be added
+ * through inheritance. It does not include token bindings, not does it include any variable upgrade patterns.
+ *
+ * NOTE: When using this module, you may need to enable the Solidity optimizer to avoid hitting the contract size limit.
+ *
+ * _Available since v4.3._
+ */
+abstract contract GovernorCompatibilityBravoUpgradeable is Initializable, IGovernorTimelockUpgradeable, IGovernorCompatibilityBravoUpgradeable, GovernorUpgradeable {
+    function __GovernorCompatibilityBravo_init() internal onlyInitializing {
+        __Context_init_unchained();
+        __ERC165_init_unchained();
+        __IGovernor_init_unchained();
+        __IGovernorTimelock_init_unchained();
+        __IGovernorCompatibilityBravo_init_unchained();
+        __GovernorCompatibilityBravo_init_unchained();
+    }
+
+    function __GovernorCompatibilityBravo_init_unchained() internal onlyInitializing {
+    }
+    using CountersUpgradeable for CountersUpgradeable.Counter;
+    using TimersUpgradeable for TimersUpgradeable.BlockNumber;
+
+    enum VoteType {
+        Against,
+        For,
+        Abstain
+    }
+
+    struct ProposalDetails {
+        address proposer;
+        address[] targets;
+        uint256[] values;
+        string[] signatures;
+        bytes[] calldatas;
+        uint256 forVotes;
+        uint256 againstVotes;
+        uint256 abstainVotes;
+        mapping(address => Receipt) receipts;
+        bytes32 descriptionHash;
+    }
+
+    mapping(uint256 => ProposalDetails) private _proposalDetails;
+
+    // solhint-disable-next-line func-name-mixedcase
+    function COUNTING_MODE() public pure virtual override returns (string memory) {
+        return "support=bravo&quorum=bravo";
+    }
+
+    // ============================================== Proposal lifecycle ==============================================
+    /**
+     * @dev See {IGovernor-propose}.
+     */
+    function propose(
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        string memory description
+    ) public virtual override(IGovernorUpgradeable, GovernorUpgradeable) returns (uint256) {
+        _storeProposal(_msgSender(), targets, values, new string[](calldatas.length), calldatas, description);
+        return super.propose(targets, values, calldatas, description);
+    }
+
+    /**
+     * @dev See {IGovernorCompatibilityBravo-propose}.
+     */
+    function propose(
+        address[] memory targets,
+        uint256[] memory values,
+        string[] memory signatures,
+        bytes[] memory calldatas,
+        string memory description
+    ) public virtual override returns (uint256) {
+        _storeProposal(_msgSender(), targets, values, signatures, calldatas, description);
+        return propose(targets, values, _encodeCalldata(signatures, calldatas), description);
+    }
+
+    /**
+     * @dev See {IGovernorCompatibilityBravo-queue}.
+     */
+    function queue(uint256 proposalId) public virtual override {
+        ProposalDetails storage details = _proposalDetails[proposalId];
+        queue(
+            details.targets,
+            details.values,
+            _encodeCalldata(details.signatures, details.calldatas),
+            details.descriptionHash
+        );
+    }
+
+    /**
+     * @dev See {IGovernorCompatibilityBravo-execute}.
+     */
+    function execute(uint256 proposalId) public payable virtual override {
+        ProposalDetails storage details = _proposalDetails[proposalId];
+        execute(
+            details.targets,
+            details.values,
+            _encodeCalldata(details.signatures, details.calldatas),
+            details.descriptionHash
+        );
+    }
+
+    function cancel(uint256 proposalId) public virtual override {
+        ProposalDetails storage details = _proposalDetails[proposalId];
+
+        require(
+            _msgSender() == details.proposer || getVotes(details.proposer, block.number - 1) < proposalThreshold(),
+            "GovernorBravo: proposer above threshold"
+        );
+
+        _cancel(
+            details.targets,
+            details.values,
+            _encodeCalldata(details.signatures, details.calldatas),
+            details.descriptionHash
+        );
+    }
+
+    /**
+     * @dev Encodes calldatas with optional function signature.
+     */
+    function _encodeCalldata(string[] memory signatures, bytes[] memory calldatas)
+        private
+        pure
+        returns (bytes[] memory)
+    {
+        bytes[] memory fullcalldatas = new bytes[](calldatas.length);
+
+        for (uint256 i = 0; i < signatures.length; ++i) {
+            fullcalldatas[i] = bytes(signatures[i]).length == 0
+                ? calldatas[i]
+                : abi.encodePacked(bytes4(keccak256(bytes(signatures[i]))), calldatas[i]);
+        }
+
+        return fullcalldatas;
+    }
+
+    /**
+     * @dev Store proposal metadata for later lookup
+     */
+    function _storeProposal(
+        address proposer,
+        address[] memory targets,
+        uint256[] memory values,
+        string[] memory signatures,
+        bytes[] memory calldatas,
+        string memory description
+    ) private {
+        bytes32 descriptionHash = keccak256(bytes(description));
+        uint256 proposalId = hashProposal(targets, values, _encodeCalldata(signatures, calldatas), descriptionHash);
+
+        ProposalDetails storage details = _proposalDetails[proposalId];
+        if (details.descriptionHash == bytes32(0)) {
+            details.proposer = proposer;
+            details.targets = targets;
+            details.values = values;
+            details.signatures = signatures;
+            details.calldatas = calldatas;
+            details.descriptionHash = descriptionHash;
+        }
+    }
+
+    // ==================================================== Views =====================================================
+    /**
+     * @dev See {IGovernorCompatibilityBravo-proposals}.
+     */
+    function proposals(uint256 proposalId)
+        public
+        view
+        virtual
+        override
+        returns (
+            uint256 id,
+            address proposer,
+            uint256 eta,
+            uint256 startBlock,
+            uint256 endBlock,
+            uint256 forVotes,
+            uint256 againstVotes,
+            uint256 abstainVotes,
+            bool canceled,
+            bool executed
+        )
+    {
+        id = proposalId;
+        eta = proposalEta(proposalId);
+        startBlock = proposalSnapshot(proposalId);
+        endBlock = proposalDeadline(proposalId);
+
+        ProposalDetails storage details = _proposalDetails[proposalId];
+        proposer = details.proposer;
+        forVotes = details.forVotes;
+        againstVotes = details.againstVotes;
+        abstainVotes = details.abstainVotes;
+
+        ProposalState status = state(proposalId);
+        canceled = status == ProposalState.Canceled;
+        executed = status == ProposalState.Executed;
+    }
+
+    /**
+     * @dev See {IGovernorCompatibilityBravo-getActions}.
+     */
+    function getActions(uint256 proposalId)
+        public
+        view
+        virtual
+        override
+        returns (
+            address[] memory targets,
+            uint256[] memory values,
+            string[] memory signatures,
+            bytes[] memory calldatas
+        )
+    {
+        ProposalDetails storage details = _proposalDetails[proposalId];
+        return (details.targets, details.values, details.signatures, details.calldatas);
+    }
+
+    /**
+     * @dev See {IGovernorCompatibilityBravo-getReceipt}.
+     */
+    function getReceipt(uint256 proposalId, address voter) public view virtual override returns (Receipt memory) {
+        return _proposalDetails[proposalId].receipts[voter];
+    }
+
+    /**
+     * @dev See {IGovernorCompatibilityBravo-quorumVotes}.
+     */
+    function quorumVotes() public view virtual override returns (uint256) {
+        return quorum(block.number - 1);
+    }
+
+    // ==================================================== Voting ====================================================
+    /**
+     * @dev See {IGovernor-hasVoted}.
+     */
+    function hasVoted(uint256 proposalId, address account) public view virtual override returns (bool) {
+        return _proposalDetails[proposalId].receipts[account].hasVoted;
+    }
+
+    /**
+     * @dev See {Governor-_quorumReached}. In this module, only forVotes count toward the quorum.
+     */
+    function _quorumReached(uint256 proposalId) internal view virtual override returns (bool) {
+        ProposalDetails storage details = _proposalDetails[proposalId];
+        return quorum(proposalSnapshot(proposalId)) <= details.forVotes;
+    }
+
+    /**
+     * @dev See {Governor-_voteSucceeded}. In this module, the forVotes must be scritly over the againstVotes.
+     */
+    function _voteSucceeded(uint256 proposalId) internal view virtual override returns (bool) {
+        ProposalDetails storage details = _proposalDetails[proposalId];
+        return details.forVotes > details.againstVotes;
+    }
+
+    /**
+     * @dev See {Governor-_countVote}. In this module, the support follows Governor Bravo.
+     */
+    function _countVote(
+        uint256 proposalId,
+        address account,
+        uint8 support,
+        uint256 weight
+    ) internal virtual override {
+        ProposalDetails storage details = _proposalDetails[proposalId];
+        Receipt storage receipt = details.receipts[account];
+
+        require(!receipt.hasVoted, "GovernorCompatibilityBravo: vote already cast");
+        receipt.hasVoted = true;
+        receipt.support = support;
+        receipt.votes = SafeCastUpgradeable.toUint96(weight);
+
+        if (support == uint8(VoteType.Against)) {
+            details.againstVotes += weight;
+        } else if (support == uint8(VoteType.For)) {
+            details.forVotes += weight;
+        } else if (support == uint8(VoteType.Abstain)) {
+            details.abstainVotes += weight;
+        } else {
+            revert("GovernorCompatibilityBravo: invalid vote type");
+        }
+    }
+    uint256[49] private __gap;
+}

contracts/governance/compatibility/IGovernorCompatibilityBravoUpgradeable.sol

@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (governance/compatibility/IGovernorCompatibilityBravo.sol)
+
+pragma solidity ^0.8.0;
+
+import "../IGovernorUpgradeable.sol";
+import "../../proxy/utils/Initializable.sol";
+
+/**
+ * @dev Interface extension that adds missing functions to the {Governor} core to provide `GovernorBravo` compatibility.
+ *
+ * _Available since v4.3._
+ */
+abstract contract IGovernorCompatibilityBravoUpgradeable is Initializable, IGovernorUpgradeable {
+    function __IGovernorCompatibilityBravo_init() internal onlyInitializing {
+        __IGovernor_init_unchained();
+        __IGovernorCompatibilityBravo_init_unchained();
+    }
+
+    function __IGovernorCompatibilityBravo_init_unchained() internal onlyInitializing {
+    }
+    /**
+     * @dev Proposal structure from Compound Governor Bravo. Not actually used by the compatibility layer, as
+     * {{proposal}} returns a very different structure.
+     */
+    struct Proposal {
+        uint256 id;
+        address proposer;
+        uint256 eta;
+        address[] targets;
+        uint256[] values;
+        string[] signatures;
+        bytes[] calldatas;
+        uint256 startBlock;
+        uint256 endBlock;
+        uint256 forVotes;
+        uint256 againstVotes;
+        uint256 abstainVotes;
+        bool canceled;
+        bool executed;
+        mapping(address => Receipt) receipts;
+    }
+
+    /**
+     * @dev Receipt structure from Compound Governor Bravo
+     */
+    struct Receipt {
+        bool hasVoted;
+        uint8 support;
+        uint96 votes;
+    }
+
+    /**
+     * @dev Part of the Governor Bravo's interface.
+     */
+    function quorumVotes() public view virtual returns (uint256);
+
+    /**
+     * @dev Part of the Governor Bravo's interface: _"The official record of all proposals ever proposed"_.
+     */
+    function proposals(uint256)
+        public
+        view
+        virtual
+        returns (
+            uint256 id,
+            address proposer,
+            uint256 eta,
+            uint256 startBlock,
+            uint256 endBlock,
+            uint256 forVotes,
+            uint256 againstVotes,
+            uint256 abstainVotes,
+            bool canceled,
+            bool executed
+        );
+
+    /**
+     * @dev Part of the Governor Bravo's interface: _"Function used to propose a new proposal"_.
+     */
+    function propose(
+        address[] memory targets,
+        uint256[] memory values,
+        string[] memory signatures,
+        bytes[] memory calldatas,
+        string memory description
+    ) public virtual returns (uint256);
+
+    /**
+     * @dev Part of the Governor Bravo's interface: _"Queues a proposal of state succeeded"_.
+     */
+    function queue(uint256 proposalId) public virtual;
+
+    /**
+     * @dev Part of the Governor Bravo's interface: _"Executes a queued proposal if eta has passed"_.
+     */
+    function execute(uint256 proposalId) public payable virtual;
+
+    /**
+     * @dev Cancels a proposal only if sender is the proposer, or proposer delegates dropped below proposal threshold.
+     */
+    function cancel(uint256 proposalId) public virtual;
+
+    /**
+     * @dev Part of the Governor Bravo's interface: _"Gets actions of a proposal"_.
+     */
+    function getActions(uint256 proposalId)
+        public
+        view
+        virtual
+        returns (
+            address[] memory targets,
+            uint256[] memory values,
+            string[] memory signatures,
+            bytes[] memory calldatas
+        );
+
+    /**
+     * @dev Part of the Governor Bravo's interface: _"Gets the receipt for a voter on a given proposal"_.
+     */
+    function getReceipt(uint256 proposalId, address voter) public view virtual returns (Receipt memory);
+    uint256[50] private __gap;
+}

contracts/governance/extensions/GovernorCountingSimpleUpgradeable.sol

@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (governance/extensions/GovernorCountingSimple.sol)
+
+pragma solidity ^0.8.0;
+
+import "../GovernorUpgradeable.sol";
+import "../../proxy/utils/Initializable.sol";
+
+/**
+ * @dev Extension of {Governor} for simple, 3 options, vote counting.
+ *
+ * _Available since v4.3._
+ */
+abstract contract GovernorCountingSimpleUpgradeable is Initializable, GovernorUpgradeable {
+    function __GovernorCountingSimple_init() internal onlyInitializing {
+        __Context_init_unchained();
+        __ERC165_init_unchained();
+        __IGovernor_init_unchained();
+        __GovernorCountingSimple_init_unchained();
+    }
+
+    function __GovernorCountingSimple_init_unchained() internal onlyInitializing {
+    }
+    /**
+     * @dev Supported vote types. Matches Governor Bravo ordering.
+     */
+    enum VoteType {
+        Against,
+        For,
+        Abstain
+    }
+
+    struct ProposalVote {
+        uint256 againstVotes;
+        uint256 forVotes;
+        uint256 abstainVotes;
+        mapping(address => bool) hasVoted;
+    }
+
+    mapping(uint256 => ProposalVote) private _proposalVotes;
+
+    /**
+     * @dev See {IGovernor-COUNTING_MODE}.
+     */
+    // solhint-disable-next-line func-name-mixedcase
+    function COUNTING_MODE() public pure virtual override returns (string memory) {
+        return "support=bravo&quorum=for,abstain";
+    }
+
+    /**
+     * @dev See {IGovernor-hasVoted}.
+     */
+    function hasVoted(uint256 proposalId, address account) public view virtual override returns (bool) {
+        return _proposalVotes[proposalId].hasVoted[account];
+    }
+
+    /**
+     * @dev Accessor to the internal vote counts.
+     */
+    function proposalVotes(uint256 proposalId)
+        public
+        view
+        virtual
+        returns (
+            uint256 againstVotes,
+            uint256 forVotes,
+            uint256 abstainVotes
+        )
+    {
+        ProposalVote storage proposalvote = _proposalVotes[proposalId];
+        return (proposalvote.againstVotes, proposalvote.forVotes, proposalvote.abstainVotes);
+    }
+
+    /**
+     * @dev See {Governor-_quorumReached}.
+     */
+    function _quorumReached(uint256 proposalId) internal view virtual override returns (bool) {
+        ProposalVote storage proposalvote = _proposalVotes[proposalId];
+
+        return quorum(proposalSnapshot(proposalId)) <= proposalvote.forVotes + proposalvote.abstainVotes;
+    }
+
+    /**
+     * @dev See {Governor-_voteSucceeded}. In this module, the forVotes must be strictly over the againstVotes.
+     */
+    function _voteSucceeded(uint256 proposalId) internal view virtual override returns (bool) {
+        ProposalVote storage proposalvote = _proposalVotes[proposalId];
+
+        return proposalvote.forVotes > proposalvote.againstVotes;
+    }
+
+    /**
+     * @dev See {Governor-_countVote}. In this module, the support follows the `VoteType` enum (from Governor Bravo).
+     */
+    function _countVote(
+        uint256 proposalId,
+        address account,
+        uint8 support,
+        uint256 weight
+    ) internal virtual override {
+        ProposalVote storage proposalvote = _proposalVotes[proposalId];
+
+        require(!proposalvote.hasVoted[account], "GovernorVotingSimple: vote already cast");
+        proposalvote.hasVoted[account] = true;
+
+        if (support == uint8(VoteType.Against)) {
+            proposalvote.againstVotes += weight;
+        } else if (support == uint8(VoteType.For)) {
+            proposalvote.forVotes += weight;
+        } else if (support == uint8(VoteType.Abstain)) {
+            proposalvote.abstainVotes += weight;
+        } else {
+            revert("GovernorVotingSimple: invalid value for enum VoteType");
+        }
+    }
+    uint256[49] private __gap;
+}

contracts/governance/extensions/GovernorPreventLateQuorumUpgradeable.sol

@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v4.5.0-rc.0) (governance/extensions/GovernorPreventLateQuorum.sol)
+
+pragma solidity ^0.8.0;
+
+import "../GovernorUpgradeable.sol";
+import "../../utils/math/MathUpgradeable.sol";
+import "../../proxy/utils/Initializable.sol";
+
+/**
+ * @dev A module that ensures there is a minimum voting period after quorum is reached. This prevents a large voter from
+ * swaying a vote and triggering quorum at the last minute, by ensuring there is always time for other voters to react
+ * and try to oppose the decision.
+ *
+ * If a vote causes quorum to be reached, the proposal's voting period may be extended so that it does not end before at
+ * least a given number of blocks have passed (the "vote extension" parameter). This parameter can be set by the
+ * governance executor (e.g. through a governance proposal).
+ *
+ * _Available since v4.5._
+ */
+abstract contract GovernorPreventLateQuorumUpgradeable is Initializable, GovernorUpgradeable {
+    using SafeCastUpgradeable for uint256;
+    using TimersUpgradeable for TimersUpgradeable.BlockNumber;
+
+    uint64 private _voteExtension;
+    mapping(uint256 => TimersUpgradeable.BlockNumber) private _extendedDeadlines;
+
+    /// @dev Emitted when a proposal deadline is pushed back due to reaching quorum late in its voting period.
+    event ProposalExtended(uint256 indexed proposalId, uint64 extendedDeadline);
+
+    /// @dev Emitted when the {lateQuorumVoteExtension} parameter is changed.
+    event LateQuorumVoteExtensionSet(uint64 oldVoteExtension, uint64 newVoteExtension);
+
+    /**
+     * @dev Initializes the vote extension parameter: the number of blocks that are required to pass since a proposal
+     * reaches quorum until its voting period ends. If necessary the voting period will be extended beyond the one set
+     * at proposal creation.
+     */
+    function __GovernorPreventLateQuorum_init(uint64 initialVoteExtension) internal onlyInitializing {
+        __Context_init_unchained();
+        __ERC165_init_unchained();
+        __IGovernor_init_unchained();
+        __GovernorPreventLateQuorum_init_unchained(initialVoteExtension);
+    }
+
+    function __GovernorPreventLateQuorum_init_unchained(uint64 initialVoteExtension) internal onlyInitializing {
+        _setLateQuorumVoteExtension(initialVoteExtension);
+    }
+
+    /**
+     * @dev Returns the proposal deadline, which may have been extended beyond that set at proposal creation, if the
+     * proposal reached quorum late in the voting period. See {Governor-proposalDeadline}.
+     */
+    function proposalDeadline(uint256 proposalId) public view virtual override returns (uint256) {
+        return MathUpgradeable.max(super.proposalDeadline(proposalId), _extendedDeadlines[proposalId].getDeadline());
+    }
+
+    /**
+     * @dev Casts a vote and detects if it caused quorum to be reached, potentially extending the voting period. See
+     * {Governor-_castVote}.
+     *
+     * May emit a {ProposalExtended} event.
+     */
+    function _castVote(
+        uint256 proposalId,
+        address account,
+        uint8 support,
+        string memory reason
+    ) internal virtual override returns (uint256) {
+        uint256 result = super._castVote(proposalId, account, support, reason);
+
+        TimersUpgradeable.BlockNumber storage extendedDeadline = _extendedDeadlines[proposalId];
+
+        if (extendedDeadline.isUnset() && _quorumReached(proposalId)) {
+            uint64 extendedDeadlineValue = block.number.toUint64() + lateQuorumVoteExtension();
+
+            if (extendedDeadlineValue > proposalDeadline(proposalId)) {
+                emit ProposalExtended(proposalId, extendedDeadlineValue);
+            }
+
+            extendedDeadline.setDeadline(extendedDeadlineValue);
+        }
+
+        return result;
+    }
+
+    /**
+     * @dev Returns the current value of the vote extension parameter: the number of blocks that are required to pass
+     * from the time a proposal reaches quorum until its voting period ends.
+     */
+    function lateQuorumVoteExtension() public view virtual returns (uint64) {
+        return _voteExtension;
+    }
+
+    /**
+     * @dev Changes the {lateQuorumVoteExtension}. This operation can only be performed by the governance executor,
+     * generally through a governance proposal.
+     *
+     * Emits a {LateQuorumVoteExtensionSet} event.
+     */
+    function setLateQuorumVoteExtension(uint64 newVoteExtension) public virtual onlyGovernance {
+        _setLateQuorumVoteExtension(newVoteExtension);
+    }
+
+    /**
+     * @dev Changes the {lateQuorumVoteExtension}. This is an internal function that can be exposed in a public function
+     * like {setLateQuorumVoteExtension} if another access control mechanism is needed.
+     *
+     * Emits a {LateQuorumVoteExtensionSet} event.
+     */
+    function _setLateQuorumVoteExtension(uint64 newVoteExtension) internal virtual {
+        emit LateQuorumVoteExtensionSet(_voteExtension, newVoteExtension);
+        _voteExtension = newVoteExtension;
+    }
+    uint256[48] private __gap;
+}

contracts/governance/extensions/GovernorProposalThresholdUpgradeable.sol

@@ -0,0 +1,34 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (governance/extensions/GovernorProposalThreshold.sol)
+
+pragma solidity ^0.8.0;
+
+import "../GovernorUpgradeable.sol";
+import "../../proxy/utils/Initializable.sol";
+
+/**
+ * @dev Extension of {Governor} for proposal restriction to token holders with a minimum balance.
+ *
+ * _Available since v4.3._
+ * _Deprecated since v4.4._
+ */
+abstract contract GovernorProposalThresholdUpgradeable is Initializable, GovernorUpgradeable {
+    function __GovernorProposalThreshold_init() internal onlyInitializing {
+        __Context_init_unchained();
+        __ERC165_init_unchained();
+        __IGovernor_init_unchained();
+        __GovernorProposalThreshold_init_unchained();
+    }
+
+    function __GovernorProposalThreshold_init_unchained() internal onlyInitializing {
+    }
+    function propose(
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        string memory description
+    ) public virtual override returns (uint256) {
+        return super.propose(targets, values, calldatas, description);
+    }
+    uint256[50] private __gap;
+}

contracts/governance/extensions/GovernorSettingsUpgradeable.sol

@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (governance/extensions/GovernorSettings.sol)
+
+pragma solidity ^0.8.0;
+
+import "../GovernorUpgradeable.sol";
+import "../../proxy/utils/Initializable.sol";
+
+/**
+ * @dev Extension of {Governor} for settings updatable through governance.
+ *
+ * _Available since v4.4._
+ */
+abstract contract GovernorSettingsUpgradeable is Initializable, GovernorUpgradeable {
+    uint256 private _votingDelay;
+    uint256 private _votingPeriod;
+    uint256 private _proposalThreshold;
+
+    event VotingDelaySet(uint256 oldVotingDelay, uint256 newVotingDelay);
+    event VotingPeriodSet(uint256 oldVotingPeriod, uint256 newVotingPeriod);
+    event ProposalThresholdSet(uint256 oldProposalThreshold, uint256 newProposalThreshold);
+
+    /**
+     * @dev Initialize the governance parameters.
+     */
+    function __GovernorSettings_init(
+        uint256 initialVotingDelay,
+        uint256 initialVotingPeriod,
+        uint256 initialProposalThreshold
+    ) internal onlyInitializing {
+        __Context_init_unchained();
+        __ERC165_init_unchained();
+        __IGovernor_init_unchained();
+        __GovernorSettings_init_unchained(initialVotingDelay, initialVotingPeriod, initialProposalThreshold);
+    }
+
+    function __GovernorSettings_init_unchained(
+        uint256 initialVotingDelay,
+        uint256 initialVotingPeriod,
+        uint256 initialProposalThreshold
+    ) internal onlyInitializing {
+        _setVotingDelay(initialVotingDelay);
+        _setVotingPeriod(initialVotingPeriod);
+        _setProposalThreshold(initialProposalThreshold);
+    }
+
+    /**
+     * @dev See {IGovernor-votingDelay}.
+     */
+    function votingDelay() public view virtual override returns (uint256) {
+        return _votingDelay;
+    }
+
+    /**
+     * @dev See {IGovernor-votingPeriod}.
+     */
+    function votingPeriod() public view virtual override returns (uint256) {
+        return _votingPeriod;
+    }
+
+    /**
+     * @dev See {Governor-proposalThreshold}.
+     */
+    function proposalThreshold() public view virtual override returns (uint256) {
+        return _proposalThreshold;
+    }
+
+    /**
+     * @dev Update the voting delay. This operation can only be performed through a governance proposal.
+     *
+     * Emits a {VotingDelaySet} event.
+     */
+    function setVotingDelay(uint256 newVotingDelay) public virtual onlyGovernance {
+        _setVotingDelay(newVotingDelay);
+    }
+
+    /**
+     * @dev Update the voting period. This operation can only be performed through a governance proposal.
+     *
+     * Emits a {VotingPeriodSet} event.
+     */
+    function setVotingPeriod(uint256 newVotingPeriod) public virtual onlyGovernance {
+        _setVotingPeriod(newVotingPeriod);
+    }
+
+    /**
+     * @dev Update the proposal threshold. This operation can only be performed through a governance proposal.
+     *
+     * Emits a {ProposalThresholdSet} event.
+     */
+    function setProposalThreshold(uint256 newProposalThreshold) public virtual onlyGovernance {
+        _setProposalThreshold(newProposalThreshold);
+    }
+
+    /**
+     * @dev Internal setter for the voting delay.
+     *
+     * Emits a {VotingDelaySet} event.
+     */
+    function _setVotingDelay(uint256 newVotingDelay) internal virtual {
+        emit VotingDelaySet(_votingDelay, newVotingDelay);
+        _votingDelay = newVotingDelay;
+    }
+
+    /**
+     * @dev Internal setter for the voting period.
+     *
+     * Emits a {VotingPeriodSet} event.
+     */
+    function _setVotingPeriod(uint256 newVotingPeriod) internal virtual {
+        // voting period must be at least one block long
+        require(newVotingPeriod > 0, "GovernorSettings: voting period too low");
+        emit VotingPeriodSet(_votingPeriod, newVotingPeriod);
+        _votingPeriod = newVotingPeriod;
+    }
+
+    /**
+     * @dev Internal setter for the proposal threshold.
+     *
+     * Emits a {ProposalThresholdSet} event.
+     */
+    function _setProposalThreshold(uint256 newProposalThreshold) internal virtual {
+        emit ProposalThresholdSet(_proposalThreshold, newProposalThreshold);
+        _proposalThreshold = newProposalThreshold;
+    }
+    uint256[47] private __gap;
+}

contracts/governance/extensions/GovernorTimelockCompoundUpgradeable.sol

@@ -0,0 +1,254 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (governance/extensions/GovernorTimelockCompound.sol)
+
+pragma solidity ^0.8.0;
+
+import "./IGovernorTimelockUpgradeable.sol";
+import "../GovernorUpgradeable.sol";
+import "../../utils/math/SafeCastUpgradeable.sol";
+import "../../proxy/utils/Initializable.sol";
+
+/**
+ * https://github.com/compound-finance/compound-protocol/blob/master/contracts/Timelock.sol[Compound's timelock] interface
+ */
+interface ICompoundTimelockUpgradeable {
+    receive() external payable;
+
+    // solhint-disable-next-line func-name-mixedcase
+    function GRACE_PERIOD() external view returns (uint256);
+
+    // solhint-disable-next-line func-name-mixedcase
+    function MINIMUM_DELAY() external view returns (uint256);
+
+    // solhint-disable-next-line func-name-mixedcase
+    function MAXIMUM_DELAY() external view returns (uint256);
+
+    function admin() external view returns (address);
+
+    function pendingAdmin() external view returns (address);
+
+    function delay() external view returns (uint256);
+
+    function queuedTransactions(bytes32) external view returns (bool);
+
+    function setDelay(uint256) external;
+
+    function acceptAdmin() external;
+
+    function setPendingAdmin(address) external;
+
+    function queueTransaction(
+        address target,
+        uint256 value,
+        string memory signature,
+        bytes memory data,
+        uint256 eta
+    ) external returns (bytes32);
+
+    function cancelTransaction(
+        address target,
+        uint256 value,
+        string memory signature,
+        bytes memory data,
+        uint256 eta
+    ) external;
+
+    function executeTransaction(
+        address target,
+        uint256 value,
+        string memory signature,
+        bytes memory data,
+        uint256 eta
+    ) external payable returns (bytes memory);
+}
+
+/**
+ * @dev Extension of {Governor} that binds the execution process to a Compound Timelock. This adds a delay, enforced by
+ * the external timelock to all successful proposal (in addition to the voting duration). The {Governor} needs to be
+ * the admin of the timelock for any operation to be performed. A public, unrestricted,
+ * {GovernorTimelockCompound-__acceptAdmin} is available to accept ownership of the timelock.
+ *
+ * Using this model means the proposal will be operated by the {TimelockController} and not by the {Governor}. Thus,
+ * the assets and permissions must be attached to the {TimelockController}. Any asset sent to the {Governor} will be
+ * inaccessible.
+ *
+ * _Available since v4.3._
+ */
+abstract contract GovernorTimelockCompoundUpgradeable is Initializable, IGovernorTimelockUpgradeable, GovernorUpgradeable {
+    using SafeCastUpgradeable for uint256;
+    using TimersUpgradeable for TimersUpgradeable.Timestamp;
+
+    struct ProposalTimelock {
+        TimersUpgradeable.Timestamp timer;
+    }
+
+    ICompoundTimelockUpgradeable private _timelock;
+
+    mapping(uint256 => ProposalTimelock) private _proposalTimelocks;
+
+    /**
+     * @dev Emitted when the timelock controller used for proposal execution is modified.
+     */
+    event TimelockChange(address oldTimelock, address newTimelock);
+
+    /**
+     * @dev Set the timelock.
+     */
+    function __GovernorTimelockCompound_init(ICompoundTimelockUpgradeable timelockAddress) internal onlyInitializing {
+        __Context_init_unchained();
+        __ERC165_init_unchained();
+        __IGovernor_init_unchained();
+        __IGovernorTimelock_init_unchained();
+        __GovernorTimelockCompound_init_unchained(timelockAddress);
+    }
+
+    function __GovernorTimelockCompound_init_unchained(ICompoundTimelockUpgradeable timelockAddress) internal onlyInitializing {
+        _updateTimelock(timelockAddress);
+    }
+
+    /**
+     * @dev See {IERC165-supportsInterface}.
+     */
+    function supportsInterface(bytes4 interfaceId) public view virtual override(IERC165Upgradeable, GovernorUpgradeable) returns (bool) {
+        return interfaceId == type(IGovernorTimelockUpgradeable).interfaceId || super.supportsInterface(interfaceId);
+    }
+
+    /**
+     * @dev Overriden version of the {Governor-state} function with added support for the `Queued` and `Expired` status.
+     */
+    function state(uint256 proposalId) public view virtual override(IGovernorUpgradeable, GovernorUpgradeable) returns (ProposalState) {
+        ProposalState status = super.state(proposalId);
+
+        if (status != ProposalState.Succeeded) {
+            return status;
+        }
+
+        uint256 eta = proposalEta(proposalId);
+        if (eta == 0) {
+            return status;
+        } else if (block.timestamp >= eta + _timelock.GRACE_PERIOD()) {
+            return ProposalState.Expired;
+        } else {
+            return ProposalState.Queued;
+        }
+    }
+
+    /**
+     * @dev Public accessor to check the address of the timelock
+     */
+    function timelock() public view virtual override returns (address) {
+        return address(_timelock);
+    }
+
+    /**
+     * @dev Public accessor to check the eta of a queued proposal
+     */
+    function proposalEta(uint256 proposalId) public view virtual override returns (uint256) {
+        return _proposalTimelocks[proposalId].timer.getDeadline();
+    }
+
+    /**
+     * @dev Function to queue a proposal to the timelock.
+     */
+    function queue(
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        bytes32 descriptionHash
+    ) public virtual override returns (uint256) {
+        uint256 proposalId = hashProposal(targets, values, calldatas, descriptionHash);
+
+        require(state(proposalId) == ProposalState.Succeeded, "Governor: proposal not successful");
+
+        uint256 eta = block.timestamp + _timelock.delay();
+        _proposalTimelocks[proposalId].timer.setDeadline(eta.toUint64());
+        for (uint256 i = 0; i < targets.length; ++i) {
+            require(
+                !_timelock.queuedTransactions(keccak256(abi.encode(targets[i], values[i], "", calldatas[i], eta))),
+                "GovernorTimelockCompound: identical proposal action already queued"
+            );
+            _timelock.queueTransaction(targets[i], values[i], "", calldatas[i], eta);
+        }
+
+        emit ProposalQueued(proposalId, eta);
+
+        return proposalId;
+    }
+
+    /**
+     * @dev Overriden execute function that run the already queued proposal through the timelock.
+     */
+    function _execute(
+        uint256 proposalId,
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        bytes32 /*descriptionHash*/
+    ) internal virtual override {
+        uint256 eta = proposalEta(proposalId);
+        require(eta > 0, "GovernorTimelockCompound: proposal not yet queued");
+        AddressUpgradeable.sendValue(payable(_timelock), msg.value);
+        for (uint256 i = 0; i < targets.length; ++i) {
+            _timelock.executeTransaction(targets[i], values[i], "", calldatas[i], eta);
+        }
+    }
+
+    /**
+     * @dev Overriden version of the {Governor-_cancel} function to cancel the timelocked proposal if it as already
+     * been queued.
+     */
+    function _cancel(
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        bytes32 descriptionHash
+    ) internal virtual override returns (uint256) {
+        uint256 proposalId = super._cancel(targets, values, calldatas, descriptionHash);
+
+        uint256 eta = proposalEta(proposalId);
+        if (eta > 0) {
+            for (uint256 i = 0; i < targets.length; ++i) {
+                _timelock.cancelTransaction(targets[i], values[i], "", calldatas[i], eta);
+            }
+            _proposalTimelocks[proposalId].timer.reset();
+        }
+
+        return proposalId;
+    }
+
+    /**
+     * @dev Address through which the governor executes action. In this case, the timelock.
+     */
+    function _executor() internal view virtual override returns (address) {
+        return address(_timelock);
+    }
+
+    /**
+     * @dev Accept admin right over the timelock.
+     */
+    // solhint-disable-next-line private-vars-leading-underscore
+    function __acceptAdmin() public {
+        _timelock.acceptAdmin();
+    }
+
+    /**
+     * @dev Public endpoint to update the underlying timelock instance. Restricted to the timelock itself, so updates
+     * must be proposed, scheduled and executed using the {Governor} workflow.
+     *
+     * For security reason, the timelock must be handed over to another admin before setting up a new one. The two
+     * operations (hand over the timelock) and do the update can be batched in a single proposal.
+     *
+     * Note that if the timelock admin has been handed over in a previous operation, we refuse updates made through the
+     * timelock if admin of the timelock has already been accepted and the operation is executed outside the scope of
+     * governance.
+     */
+    function updateTimelock(ICompoundTimelockUpgradeable newTimelock) external virtual onlyGovernance {
+        _updateTimelock(newTimelock);
+    }
+
+    function _updateTimelock(ICompoundTimelockUpgradeable newTimelock) private {
+        emit TimelockChange(address(_timelock), address(newTimelock));
+        _timelock = newTimelock;
+    }
+    uint256[48] private __gap;
+}

contracts/governance/extensions/GovernorTimelockControlUpgradeable.sol

@@ -0,0 +1,170 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v4.5.0-rc.0) (governance/extensions/GovernorTimelockControl.sol)
+
+pragma solidity ^0.8.0;
+
+import "./IGovernorTimelockUpgradeable.sol";
+import "../GovernorUpgradeable.sol";
+import "../TimelockControllerUpgradeable.sol";
+import "../../proxy/utils/Initializable.sol";
+
+/**
+ * @dev Extension of {Governor} that binds the execution process to an instance of {TimelockController}. This adds a
+ * delay, enforced by the {TimelockController} to all successful proposal (in addition to the voting duration). The
+ * {Governor} needs the proposer (and ideally the executor) roles for the {Governor} to work properly.
+ *
+ * Using this model means the proposal will be operated by the {TimelockController} and not by the {Governor}. Thus,
+ * the assets and permissions must be attached to the {TimelockController}. Any asset sent to the {Governor} will be
+ * inaccessible.
+ *
+ * WARNING: Setting up the TimelockController to have additional proposers besides the governor introduces the risk that
+ * approved governance proposals could be blocked by the other proposers, effectively executing a Denial of Service attack,
+ * and therefore blocking access to governance-controlled assets.
+ *
+ * _Available since v4.3._
+ */
+abstract contract GovernorTimelockControlUpgradeable is Initializable, IGovernorTimelockUpgradeable, GovernorUpgradeable {
+    TimelockControllerUpgradeable private _timelock;
+    mapping(uint256 => bytes32) private _timelockIds;
+
+    /**
+     * @dev Emitted when the timelock controller used for proposal execution is modified.
+     */
+    event TimelockChange(address oldTimelock, address newTimelock);
+
+    /**
+     * @dev Set the timelock.
+     */
+    function __GovernorTimelockControl_init(TimelockControllerUpgradeable timelockAddress) internal onlyInitializing {
+        __Context_init_unchained();
+        __ERC165_init_unchained();
+        __IGovernor_init_unchained();
+        __IGovernorTimelock_init_unchained();
+        __GovernorTimelockControl_init_unchained(timelockAddress);
+    }
+
+    function __GovernorTimelockControl_init_unchained(TimelockControllerUpgradeable timelockAddress) internal onlyInitializing {
+        _updateTimelock(timelockAddress);
+    }
+
+    /**
+     * @dev See {IERC165-supportsInterface}.
+     */
+    function supportsInterface(bytes4 interfaceId) public view virtual override(IERC165Upgradeable, GovernorUpgradeable) returns (bool) {
+        return interfaceId == type(IGovernorTimelockUpgradeable).interfaceId || super.supportsInterface(interfaceId);
+    }
+
+    /**
+     * @dev Overriden version of the {Governor-state} function with added support for the `Queued` status.
+     */
+    function state(uint256 proposalId) public view virtual override(IGovernorUpgradeable, GovernorUpgradeable) returns (ProposalState) {
+        ProposalState status = super.state(proposalId);
+
+        if (status != ProposalState.Succeeded) {
+            return status;
+        }
+
+        // core tracks execution, so we just have to check if successful proposal have been queued.
+        bytes32 queueid = _timelockIds[proposalId];
+        if (queueid == bytes32(0)) {
+            return status;
+        } else if (_timelock.isOperationDone(queueid)) {
+            return ProposalState.Executed;
+        } else if (_timelock.isOperationPending(queueid)) {
+            return ProposalState.Queued;
+        } else {
+            return ProposalState.Canceled;
+        }
+    }
+
+    /**
+     * @dev Public accessor to check the address of the timelock
+     */
+    function timelock() public view virtual override returns (address) {
+        return address(_timelock);
+    }
+
+    /**
+     * @dev Public accessor to check the eta of a queued proposal
+     */
+    function proposalEta(uint256 proposalId) public view virtual override returns (uint256) {
+        uint256 eta = _timelock.getTimestamp(_timelockIds[proposalId]);
+        return eta == 1 ? 0 : eta; // _DONE_TIMESTAMP (1) should be replaced with a 0 value
+    }
+
+    /**
+     * @dev Function to queue a proposal to the timelock.
+     */
+    function queue(
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        bytes32 descriptionHash
+    ) public virtual override returns (uint256) {
+        uint256 proposalId = hashProposal(targets, values, calldatas, descriptionHash);
+
+        require(state(proposalId) == ProposalState.Succeeded, "Governor: proposal not successful");
+
+        uint256 delay = _timelock.getMinDelay();
+        _timelockIds[proposalId] = _timelock.hashOperationBatch(targets, values, calldatas, 0, descriptionHash);
+        _timelock.scheduleBatch(targets, values, calldatas, 0, descriptionHash, delay);
+
+        emit ProposalQueued(proposalId, block.timestamp + delay);
+
+        return proposalId;
+    }
+
+    /**
+     * @dev Overriden execute function that run the already queued proposal through the timelock.
+     */
+    function _execute(
+        uint256, /* proposalId */
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        bytes32 descriptionHash
+    ) internal virtual override {
+        _timelock.executeBatch{value: msg.value}(targets, values, calldatas, 0, descriptionHash);
+    }
+
+    /**
+     * @dev Overriden version of the {Governor-_cancel} function to cancel the timelocked proposal if it as already
+     * been queued.
+     */
+    function _cancel(
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        bytes32 descriptionHash
+    ) internal virtual override returns (uint256) {
+        uint256 proposalId = super._cancel(targets, values, calldatas, descriptionHash);
+
+        if (_timelockIds[proposalId] != 0) {
+            _timelock.cancel(_timelockIds[proposalId]);
+            delete _timelockIds[proposalId];
+        }
+
+        return proposalId;
+    }
+
+    /**
+     * @dev Address through which the governor executes action. In this case, the timelock.
+     */
+    function _executor() internal view virtual override returns (address) {
+        return address(_timelock);
+    }
+
+    /**
+     * @dev Public endpoint to update the underlying timelock instance. Restricted to the timelock itself, so updates
+     * must be proposed, scheduled and executed using the {Governor} workflow.
+     */
+    function updateTimelock(TimelockControllerUpgradeable newTimelock) external virtual onlyGovernance {
+        _updateTimelock(newTimelock);
+    }
+
+    function _updateTimelock(TimelockControllerUpgradeable newTimelock) private {
+        emit TimelockChange(address(_timelock), address(newTimelock));
+        _timelock = newTimelock;
+    }
+    uint256[48] private __gap;
+}

contracts/governance/extensions/GovernorVotesCompUpgradeable.sol

@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (governance/extensions/GovernorVotesComp.sol)
+
+pragma solidity ^0.8.0;
+
+import "../GovernorUpgradeable.sol";
+import "../../token/ERC20/extensions/ERC20VotesCompUpgradeable.sol";
+import "../../proxy/utils/Initializable.sol";
+
+/**
+ * @dev Extension of {Governor} for voting weight extraction from a Comp token.
+ *
+ * _Available since v4.3._
+ */
+abstract contract GovernorVotesCompUpgradeable is Initializable, GovernorUpgradeable {
+    ERC20VotesCompUpgradeable public token;
+
+    function __GovernorVotesComp_init(ERC20VotesCompUpgradeable token_) internal onlyInitializing {
+        __Context_init_unchained();
+        __ERC165_init_unchained();
+        __IGovernor_init_unchained();
+        __GovernorVotesComp_init_unchained(token_);
+    }
+
+    function __GovernorVotesComp_init_unchained(ERC20VotesCompUpgradeable token_) internal onlyInitializing {
+        token = token_;
+    }
+
+    /**
+     * Read the voting weight from the token's built in snapshot mechanism (see {IGovernor-getVotes}).
+     */
+    function getVotes(address account, uint256 blockNumber) public view virtual override returns (uint256) {
+        return token.getPriorVotes(account, blockNumber);
+    }
+    uint256[50] private __gap;
+}

contracts/governance/extensions/GovernorVotesQuorumFractionUpgradeable.sol

@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (governance/extensions/GovernorVotesQuorumFraction.sol)
+
+pragma solidity ^0.8.0;
+
+import "./GovernorVotesUpgradeable.sol";
+import "../../proxy/utils/Initializable.sol";
+
+/**
+ * @dev Extension of {Governor} for voting weight extraction from an {ERC20Votes} token and a quorum expressed as a
+ * fraction of the total supply.
+ *
+ * _Available since v4.3._
+ */
+abstract contract GovernorVotesQuorumFractionUpgradeable is Initializable, GovernorVotesUpgradeable {
+    uint256 private _quorumNumerator;
+
+    event QuorumNumeratorUpdated(uint256 oldQuorumNumerator, uint256 newQuorumNumerator);
+
+    function __GovernorVotesQuorumFraction_init(uint256 quorumNumeratorValue) internal onlyInitializing {
+        __Context_init_unchained();
+        __ERC165_init_unchained();
+        __IGovernor_init_unchained();
+        __GovernorVotesQuorumFraction_init_unchained(quorumNumeratorValue);
+    }
+
+    function __GovernorVotesQuorumFraction_init_unchained(uint256 quorumNumeratorValue) internal onlyInitializing {
+        _updateQuorumNumerator(quorumNumeratorValue);
+    }
+
+    function quorumNumerator() public view virtual returns (uint256) {
+        return _quorumNumerator;
+    }
+
+    function quorumDenominator() public view virtual returns (uint256) {
+        return 100;
+    }
+
+    function quorum(uint256 blockNumber) public view virtual override returns (uint256) {
+        return (token.getPastTotalSupply(blockNumber) * quorumNumerator()) / quorumDenominator();
+    }
+
+    function updateQuorumNumerator(uint256 newQuorumNumerator) external virtual onlyGovernance {
+        _updateQuorumNumerator(newQuorumNumerator);
+    }
+
+    function _updateQuorumNumerator(uint256 newQuorumNumerator) internal virtual {
+        require(
+            newQuorumNumerator <= quorumDenominator(),
+            "GovernorVotesQuorumFraction: quorumNumerator over quorumDenominator"
+        );
+
+        uint256 oldQuorumNumerator = _quorumNumerator;
+        _quorumNumerator = newQuorumNumerator;
+
+        emit QuorumNumeratorUpdated(oldQuorumNumerator, newQuorumNumerator);
+    }
+    uint256[49] private __gap;
+}

contracts/governance/extensions/GovernorVotesUpgradeable.sol

@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v4.5.0-rc.0) (governance/extensions/GovernorVotes.sol)
+
+pragma solidity ^0.8.0;
+
+import "../GovernorUpgradeable.sol";
+import "../utils/IVotesUpgradeable.sol";
+import "../../proxy/utils/Initializable.sol";
+
+/**
+ * @dev Extension of {Governor} for voting weight extraction from an {ERC20Votes} token, or since v4.5 an {ERC721Votes} token.
+ *
+ * _Available since v4.3._
+ */
+abstract contract GovernorVotesUpgradeable is Initializable, GovernorUpgradeable {
+    IVotesUpgradeable public token;
+
+    function __GovernorVotes_init(IVotesUpgradeable tokenAddress) internal onlyInitializing {
+        __Context_init_unchained();
+        __ERC165_init_unchained();
+        __IGovernor_init_unchained();
+        __GovernorVotes_init_unchained(tokenAddress);
+    }
+
+    function __GovernorVotes_init_unchained(IVotesUpgradeable tokenAddress) internal onlyInitializing {
+        token = tokenAddress;
+    }
+
+    /**
+     * Read the voting weight from the token's built in snapshot mechanism (see {IGovernor-getVotes}).
+     */
+    function getVotes(address account, uint256 blockNumber) public view virtual override returns (uint256) {
+        return token.getPastVotes(account, blockNumber);
+    }
+    uint256[50] private __gap;
+}

contracts/governance/extensions/IGovernorTimelockUpgradeable.sol

@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (governance/extensions/IGovernorTimelock.sol)
+
+pragma solidity ^0.8.0;
+
+import "../IGovernorUpgradeable.sol";
+import "../../proxy/utils/Initializable.sol";
+
+/**
+ * @dev Extension of the {IGovernor} for timelock supporting modules.
+ *
+ * _Available since v4.3._
+ */
+abstract contract IGovernorTimelockUpgradeable is Initializable, IGovernorUpgradeable {
+    function __IGovernorTimelock_init() internal onlyInitializing {
+        __IGovernor_init_unchained();
+        __IGovernorTimelock_init_unchained();
+    }
+
+    function __IGovernorTimelock_init_unchained() internal onlyInitializing {
+    }
+    event ProposalQueued(uint256 proposalId, uint256 eta);
+
+    function timelock() public view virtual returns (address);
+
+    function proposalEta(uint256 proposalId) public view virtual returns (uint256);
+
+    function queue(
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        bytes32 descriptionHash
+    ) public virtual returns (uint256 proposalId);
+    uint256[50] private __gap;
+}

contracts/governance/utils/IVotesUpgradeable.sol

@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v4.5.0-rc.0) (governance/utils/IVotes.sol)
+pragma solidity ^0.8.0;
+
+/**
+ * @dev Common interface for {ERC20Votes}, {ERC721Votes}, and other {Votes}-enabled contracts.
+ *
+ * _Available since v4.5._
+ */
+interface IVotesUpgradeable {
+    /**
+     * @dev Emitted when an account changes their delegate.
+     */
+    event DelegateChanged(address indexed delegator, address indexed fromDelegate, address indexed toDelegate);
+
+    /**
+     * @dev Emitted when a token transfer or delegate change results in changes to a delegate's number of votes.
+     */
+    event DelegateVotesChanged(address indexed delegate, uint256 previousBalance, uint256 newBalance);
+
+    /**
+     * @dev Returns the current amount of votes that `account` has.
+     */
+    function getVotes(address account) external view returns (uint256);
+
+    /**
+     * @dev Returns the amount of votes that `account` had at the end of a past block (`blockNumber`).
+     */
+    function getPastVotes(address account, uint256 blockNumber) external view returns (uint256);
+
+    /**
+     * @dev Returns the total supply of votes available at the end of a past block (`blockNumber`).
+     *
+     * NOTE: This value is the sum of all available votes, which is not necessarily the sum of all delegated votes.
+     * Votes that have not been delegated are still part of total supply, even though they would not participate in a
+     * vote.
+     */
+    function getPastTotalSupply(uint256 blockNumber) external view returns (uint256);
+
+    /**
+     * @dev Returns the delegate that `account` has chosen.
+     */
+    function delegates(address account) external view returns (address);
+
+    /**
+     * @dev Delegates votes from the sender to `delegatee`.
+     */
+    function delegate(address delegatee) external;
+
+    /**
+     * @dev Delegates votes from signer to `delegatee`.
+     */
+    function delegateBySig(
+        address delegatee,
+        uint256 nonce,
+        uint256 expiry,
+        uint8 v,
+        bytes32 r,
+        bytes32 s
+    ) external;
+}

contracts/governance/utils/VotesUpgradeable.sol

@@ -0,0 +1,220 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v4.5.0-rc.0) (governance/utils/Votes.sol)
+pragma solidity ^0.8.0;
+
+import "../../utils/ContextUpgradeable.sol";
+import "../../utils/CountersUpgradeable.sol";
+import "../../utils/CheckpointsUpgradeable.sol";
+import "../../utils/cryptography/draft-EIP712Upgradeable.sol";
+import "./IVotesUpgradeable.sol";
+import "../../proxy/utils/Initializable.sol";
+
+/**
+ * @dev This is a base abstract contract that tracks voting units, which are a measure of voting power that can be
+ * transferred, and provides a system of vote delegation, where an account can delegate its voting units to a sort of
+ * "representative" that will pool delegated voting units from different accounts and can then use it to vote in
+ * decisions. In fact, voting units _must_ be delegated in order to count as actual votes, and an account has to
+ * delegate those votes to itself if it wishes to participate in decisions and does not have a trusted representative.
+ *
+ * This contract is often combined with a token contract such that voting units correspond to token units. For an
+ * example, see {ERC721Votes}.
+ *
+ * The full history of delegate votes is tracked on-chain so that governance protocols can consider votes as distributed
+ * at a particular block number to protect against flash loans and double voting. The opt-in delegate system makes the
+ * cost of this history tracking optional.
+ *
+ * When using this module the derived contract must implement {_getVotingUnits} (for example, make it return
+ * {ERC721-balanceOf}), and can use {_transferVotingUnits} to track a change in the distribution of those units (in the
+ * previous example, it would be included in {ERC721-_beforeTokenTransfer}).
+ *
+ * _Available since v4.5._
+ */
+abstract contract VotesUpgradeable is Initializable, IVotesUpgradeable, ContextUpgradeable, EIP712Upgradeable {
+    function __Votes_init() internal onlyInitializing {
+        __Context_init_unchained();
+        __Votes_init_unchained();
+    }
+
+    function __Votes_init_unchained() internal onlyInitializing {
+    }
+    using CheckpointsUpgradeable for CheckpointsUpgradeable.History;
+    using CountersUpgradeable for CountersUpgradeable.Counter;
+
+    bytes32 private constant _DELEGATION_TYPEHASH =
+        keccak256("Delegation(address delegatee,uint256 nonce,uint256 expiry)");
+
+    mapping(address => address) private _delegation;
+    mapping(address => CheckpointsUpgradeable.History) private _delegateCheckpoints;
+    CheckpointsUpgradeable.History private _totalCheckpoints;
+
+    mapping(address => CountersUpgradeable.Counter) private _nonces;
+
+    /**
+     * @dev Returns the current amount of votes that `account` has.
+     */
+    function getVotes(address account) public view virtual override returns (uint256) {
+        return _delegateCheckpoints[account].latest();
+    }
+
+    /**
+     * @dev Returns the amount of votes that `account` had at the end of a past block (`blockNumber`).
+     *
+     * Requirements:
+     *
+     * - `blockNumber` must have been already mined
+     */
+    function getPastVotes(address account, uint256 blockNumber) public view virtual override returns (uint256) {
+        return _delegateCheckpoints[account].getAtBlock(blockNumber);
+    }
+
+    /**
+     * @dev Returns the total supply of votes available at the end of a past block (`blockNumber`).
+     *
+     * NOTE: This value is the sum of all available votes, which is not necessarily the sum of all delegated votes.
+     * Votes that have not been delegated are still part of total supply, even though they would not participate in a
+     * vote.
+     *
+     * Requirements:
+     *
+     * - `blockNumber` must have been already mined
+     */
+    function getPastTotalSupply(uint256 blockNumber) public view virtual override returns (uint256) {
+        require(blockNumber < block.number, "Votes: block not yet mined");
+        return _totalCheckpoints.getAtBlock(blockNumber);
+    }
+
+    /**
+     * @dev Returns the current total supply of votes.
+     */
+    function _getTotalSupply() internal view virtual returns (uint256) {
+        return _totalCheckpoints.latest();
+    }
+
+    /**
+     * @dev Returns the delegate that `account` has chosen.
+     */
+    function delegates(address account) public view virtual override returns (address) {
+        return _delegation[account];
+    }
+
+    /**
+     * @dev Delegates votes from the sender to `delegatee`.
+     */
+    function delegate(address delegatee) public virtual override {
+        address account = _msgSender();
+        _delegate(account, delegatee);
+    }
+
+    /**
+     * @dev Delegates votes from signer to `delegatee`.
+     */
+    function delegateBySig(
+        address delegatee,
+        uint256 nonce,
+        uint256 expiry,
+        uint8 v,
+        bytes32 r,
+        bytes32 s
+    ) public virtual override {
+        require(block.timestamp <= expiry, "Votes: signature expired");
+        address signer = ECDSAUpgradeable.recover(
+            _hashTypedDataV4(keccak256(abi.encode(_DELEGATION_TYPEHASH, delegatee, nonce, expiry))),
+            v,
+            r,
+            s
+        );
+        require(nonce == _useNonce(signer), "Votes: invalid nonce");
+        _delegate(signer, delegatee);
+    }
+
+    /**
+     * @dev Delegate all of `account`'s voting units to `delegatee`.
+     *
+     * Emits events {DelegateChanged} and {DelegateVotesChanged}.
+     */
+    function _delegate(address account, address delegatee) internal virtual {
+        address oldDelegate = delegates(account);
+        _delegation[account] = delegatee;
+
+        emit DelegateChanged(account, oldDelegate, delegatee);
+        _moveDelegateVotes(oldDelegate, delegatee, _getVotingUnits(account));
+    }
+
+    /**
+     * @dev Transfers, mints, or burns voting units. To register a mint, `from` should be zero. To register a burn, `to`
+     * should be zero. Total supply of voting units will be adjusted with mints and burns.
+     */
+    function _transferVotingUnits(
+        address from,
+        address to,
+        uint256 amount
+    ) internal virtual {
+        if (from == address(0)) {
+            _totalCheckpoints.push(_add, amount);
+        }
+        if (to == address(0)) {
+            _totalCheckpoints.push(_subtract, amount);
+        }
+        _moveDelegateVotes(delegates(from), delegates(to), amount);
+    }
+
+    /**
+     * @dev Moves delegated votes from one delegate to another.
+     */
+    function _moveDelegateVotes(
+        address from,
+        address to,
+        uint256 amount
+    ) private {
+        if (from != to && amount > 0) {
+            if (from != address(0)) {
+                (uint256 oldValue, uint256 newValue) = _delegateCheckpoints[from].push(_subtract, amount);
+                emit DelegateVotesChanged(from, oldValue, newValue);
+            }
+            if (to != address(0)) {
+                (uint256 oldValue, uint256 newValue) = _delegateCheckpoints[to].push(_add, amount);
+                emit DelegateVotesChanged(to, oldValue, newValue);
+            }
+        }
+    }
+
+    function _add(uint256 a, uint256 b) private pure returns (uint256) {
+        return a + b;
+    }
+
+    function _subtract(uint256 a, uint256 b) private pure returns (uint256) {
+        return a - b;
+    }
+
+    /**
+     * @dev Consumes a nonce.
+     *
+     * Returns the current value and increments nonce.
+     */
+    function _useNonce(address owner) internal virtual returns (uint256 current) {
+        CountersUpgradeable.Counter storage nonce = _nonces[owner];
+        current = nonce.current();
+        nonce.increment();
+    }
+
+    /**
+     * @dev Returns an address nonce.
+     */
+    function nonces(address owner) public view virtual returns (uint256) {
+        return _nonces[owner].current();
+    }
+
+    /**
+     * @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.
+     */
+    function _getVotingUnits(address) internal virtual returns (uint256);
+    uint256[46] private __gap;
+}

contracts/interfaces/IERC1155MetadataURIUpgradeable.sol

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/IERC1155MetadataURI.sol)
+
+pragma solidity ^0.8.0;
+
+import "../token/ERC1155/extensions/IERC1155MetadataURIUpgradeable.sol";

contracts/interfaces/IERC1155ReceiverUpgradeable.sol

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/IERC1155Receiver.sol)
+
+pragma solidity ^0.8.0;
+
+import "../token/ERC1155/IERC1155ReceiverUpgradeable.sol";

contracts/interfaces/IERC1155Upgradeable.sol

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/IERC1155.sol)
+
+pragma solidity ^0.8.0;
+
+import "../token/ERC1155/IERC1155Upgradeable.sol";

contracts/interfaces/IERC1271Upgradeable.sol

@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/IERC1271.sol)
+
+pragma solidity ^0.8.0;
+
+/**
+ * @dev Interface of the ERC1271 standard signature validation method for
+ * contracts as defined in https://eips.ethereum.org/EIPS/eip-1271[ERC-1271].
+ *
+ * _Available since v4.1._
+ */
+interface IERC1271Upgradeable {
+    /**
+     * @dev Should return whether the signature provided is valid for the provided data
+     * @param hash      Hash of the data to be signed
+     * @param signature Signature byte array associated with _data
+     */
+    function isValidSignature(bytes32 hash, bytes memory signature) external view returns (bytes4 magicValue);
+}

contracts/interfaces/IERC1363ReceiverUpgradeable.sol

@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/IERC1363Receiver.sol)
+
+pragma solidity ^0.8.0;
+
+interface IERC1363ReceiverUpgradeable {
+    /*
+     * Note: the ERC-165 identifier for this interface is 0x88a7ca5c.
+     * 0x88a7ca5c === bytes4(keccak256("onTransferReceived(address,address,uint256,bytes)"))
+     */
+
+    /**
+     * @notice Handle the receipt of ERC1363 tokens
+     * @dev Any ERC1363 smart contract calls this function on the recipient
+     * after a `transfer` or a `transferFrom`. This function MAY throw to revert and reject the
+     * transfer. Return of other than the magic value MUST result in the
+     * transaction being reverted.
+     * Note: the token contract address is always the message sender.
+     * @param operator address The address which called `transferAndCall` or `transferFromAndCall` function
+     * @param from address The address which are token transferred from
+     * @param value uint256 The amount of tokens transferred
+     * @param data bytes Additional data with no specified format
+     * @return `bytes4(keccak256("onTransferReceived(address,address,uint256,bytes)"))`
+     *  unless throwing
+     */
+    function onTransferReceived(
+        address operator,
+        address from,
+        uint256 value,
+        bytes memory data
+    ) external returns (bytes4);
+}

contracts/interfaces/IERC1363SpenderUpgradeable.sol

@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/IERC1363Spender.sol)
+
+pragma solidity ^0.8.0;
+
+interface IERC1363SpenderUpgradeable {
+    /*
+     * Note: the ERC-165 identifier for this interface is 0x7b04a2d0.
+     * 0x7b04a2d0 === bytes4(keccak256("onApprovalReceived(address,uint256,bytes)"))
+     */
+
+    /**
+     * @notice Handle the approval of ERC1363 tokens
+     * @dev Any ERC1363 smart contract calls this function on the recipient
+     * after an `approve`. This function MAY throw to revert and reject the
+     * approval. Return of other than the magic value MUST result in the
+     * transaction being reverted.
+     * Note: the token contract address is always the message sender.
+     * @param owner address The address which called `approveAndCall` function
+     * @param value uint256 The amount of tokens to be spent
+     * @param data bytes Additional data with no specified format
+     * @return `bytes4(keccak256("onApprovalReceived(address,uint256,bytes)"))`
+     *  unless throwing
+     */
+    function onApprovalReceived(
+        address owner,
+        uint256 value,
+        bytes memory data
+    ) external returns (bytes4);
+}

contracts/interfaces/IERC1363Upgradeable.sol

@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/IERC1363.sol)
+
+pragma solidity ^0.8.0;
+
+import "./IERC20Upgradeable.sol";
+import "./IERC165Upgradeable.sol";
+
+interface IERC1363Upgradeable is IERC165Upgradeable, IERC20Upgradeable {
+    /*
+     * Note: the ERC-165 identifier for this interface is 0x4bbee2df.
+     * 0x4bbee2df ===
+     *   bytes4(keccak256('transferAndCall(address,uint256)')) ^
+     *   bytes4(keccak256('transferAndCall(address,uint256,bytes)')) ^
+     *   bytes4(keccak256('transferFromAndCall(address,address,uint256)')) ^
+     *   bytes4(keccak256('transferFromAndCall(address,address,uint256,bytes)'))
+     */
+
+    /*
+     * Note: the ERC-165 identifier for this interface is 0xfb9ec8ce.
+     * 0xfb9ec8ce ===
+     *   bytes4(keccak256('approveAndCall(address,uint256)')) ^
+     *   bytes4(keccak256('approveAndCall(address,uint256,bytes)'))
+     */
+
+    /**
+     * @dev Transfer tokens from `msg.sender` to another address and then call `onTransferReceived` on receiver
+     * @param to address The address which you want to transfer to
+     * @param value uint256 The amount of tokens to be transferred
+     * @return true unless throwing
+     */
+    function transferAndCall(address to, uint256 value) external returns (bool);
+
+    /**
+     * @dev Transfer tokens from `msg.sender` to another address and then call `onTransferReceived` on receiver
+     * @param to address The address which you want to transfer to
+     * @param value uint256 The amount of tokens to be transferred
+     * @param data bytes Additional data with no specified format, sent in call to `to`
+     * @return true unless throwing
+     */
+    function transferAndCall(
+        address to,
+        uint256 value,
+        bytes memory data
+    ) external returns (bool);
+
+    /**
+     * @dev Transfer tokens from one address to another and then call `onTransferReceived` on receiver
+     * @param from address The address which you want to send tokens from
+     * @param to address The address which you want to transfer to
+     * @param value uint256 The amount of tokens to be transferred
+     * @return true unless throwing
+     */
+    function transferFromAndCall(
+        address from,
+        address to,
+        uint256 value
+    ) external returns (bool);
+
+    /**
+     * @dev Transfer tokens from one address to another and then call `onTransferReceived` on receiver
+     * @param from address The address which you want to send tokens from
+     * @param to address The address which you want to transfer to
+     * @param value uint256 The amount of tokens to be transferred
+     * @param data bytes Additional data with no specified format, sent in call to `to`
+     * @return true unless throwing
+     */
+    function transferFromAndCall(
+        address from,
+        address to,
+        uint256 value,
+        bytes memory data
+    ) external returns (bool);
+
+    /**
+     * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender
+     * and then call `onApprovalReceived` on spender.
+     * @param spender address The address which will spend the funds
+     * @param value uint256 The amount of tokens to be spent
+     */
+    function approveAndCall(address spender, uint256 value) external returns (bool);
+
+    /**
+     * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender
+     * and then call `onApprovalReceived` on spender.
+     * @param spender address The address which will spend the funds
+     * @param value uint256 The amount of tokens to be spent
+     * @param data bytes Additional data with no specified format, sent in call to `spender`
+     */
+    function approveAndCall(
+        address spender,
+        uint256 value,
+        bytes memory data
+    ) external returns (bool);
+}

contracts/interfaces/IERC165Upgradeable.sol

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/IERC165.sol)
+
+pragma solidity ^0.8.0;
+
+import "../utils/introspection/IERC165Upgradeable.sol";

contracts/interfaces/IERC1820ImplementerUpgradeable.sol

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/IERC1820Implementer.sol)
+
+pragma solidity ^0.8.0;
+
+import "../utils/introspection/IERC1820ImplementerUpgradeable.sol";

contracts/interfaces/IERC1820RegistryUpgradeable.sol

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/IERC1820Registry.sol)
+
+pragma solidity ^0.8.0;
+
+import "../utils/introspection/IERC1820RegistryUpgradeable.sol";

contracts/interfaces/IERC20MetadataUpgradeable.sol

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/IERC20Metadata.sol)
+
+pragma solidity ^0.8.0;
+
+import "../token/ERC20/extensions/IERC20MetadataUpgradeable.sol";

contracts/interfaces/IERC20Upgradeable.sol

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/IERC20.sol)
+
+pragma solidity ^0.8.0;
+
+import "../token/ERC20/IERC20Upgradeable.sol";

contracts/interfaces/IERC2981Upgradeable.sol

@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v4.5.0-rc.0) (interfaces/IERC2981.sol)
+
+pragma solidity ^0.8.0;
+
+import "./IERC165Upgradeable.sol";
+
+/**
+ * @dev Interface for the NFT Royalty Standard.
+ *
+ * A standardized way to retrieve royalty payment information for non-fungible tokens (NFTs) to enable universal
+ * support for royalty payments across all NFT marketplaces and ecosystem participants.
+ *
+ * _Available since v4.5._
+ */
+interface IERC2981Upgradeable is IERC165Upgradeable {
+    /**
+     * @dev Returns how much royalty is owed and to whom, based on a sale price that may be denominated in any unit of
+     * exchange. The royalty amount is denominated and should be payed in that same unit of exchange.
+     */
+    function royaltyInfo(uint256 tokenId, uint256 salePrice)
+        external
+        view
+        returns (address receiver, uint256 royaltyAmount);
+}

contracts/interfaces/IERC3156FlashBorrowerUpgradeable.sol

@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/IERC3156FlashBorrower.sol)
+
+pragma solidity ^0.8.0;
+
+/**
+ * @dev Interface of the ERC3156 FlashBorrower, as defined in
+ * https://eips.ethereum.org/EIPS/eip-3156[ERC-3156].
+ *
+ * _Available since v4.1._
+ */
+interface IERC3156FlashBorrowerUpgradeable {
+    /**
+     * @dev Receive a flash loan.
+     * @param initiator The initiator of the loan.
+     * @param token The loan currency.
+     * @param amount The amount of tokens lent.
+     * @param fee The additional amount of tokens to repay.
+     * @param data Arbitrary data structure, intended to contain user-defined parameters.
+     * @return The keccak256 hash of "ERC3156FlashBorrower.onFlashLoan"
+     */
+    function onFlashLoan(
+        address initiator,
+        address token,
+        uint256 amount,
+        uint256 fee,
+        bytes calldata data
+    ) external returns (bytes32);
+}

contracts/interfaces/IERC3156FlashLenderUpgradeable.sol

@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/IERC3156FlashLender.sol)
+
+pragma solidity ^0.8.0;
+
+import "./IERC3156FlashBorrowerUpgradeable.sol";
+
+/**
+ * @dev Interface of the ERC3156 FlashLender, as defined in
+ * https://eips.ethereum.org/EIPS/eip-3156[ERC-3156].
+ *
+ * _Available since v4.1._
+ */
+interface IERC3156FlashLenderUpgradeable {
+    /**
+     * @dev The amount of currency available to be lended.
+     * @param token The loan currency.
+     * @return The amount of `token` that can be borrowed.
+     */
+    function maxFlashLoan(address token) external view returns (uint256);
+
+    /**
+     * @dev The fee to be charged for a given loan.
+     * @param token The loan currency.
+     * @param amount The amount of tokens lent.
+     * @return The amount of `token` to be charged for the loan, on top of the returned principal.
+     */
+    function flashFee(address token, uint256 amount) external view returns (uint256);
+
+    /**
+     * @dev Initiate a flash loan.
+     * @param receiver The receiver of the tokens in the loan, and the receiver of the callback.
+     * @param token The loan currency.
+     * @param amount The amount of tokens lent.
+     * @param data Arbitrary data structure, intended to contain user-defined parameters.
+     */
+    function flashLoan(
+        IERC3156FlashBorrowerUpgradeable receiver,
+        address token,
+        uint256 amount,
+        bytes calldata data
+    ) external returns (bool);
+}

contracts/interfaces/IERC3156Upgradeable.sol

@@ -0,0 +1,7 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/IERC3156.sol)
+
+pragma solidity ^0.8.0;
+
+import "./IERC3156FlashBorrowerUpgradeable.sol";
+import "./IERC3156FlashLenderUpgradeable.sol";

contracts/interfaces/IERC721EnumerableUpgradeable.sol

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/IERC721Enumerable.sol)
+
+pragma solidity ^0.8.0;
+
+import "../token/ERC721/extensions/IERC721EnumerableUpgradeable.sol";

contracts/interfaces/IERC721MetadataUpgradeable.sol

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/IERC721Metadata.sol)
+
+pragma solidity ^0.8.0;
+
+import "../token/ERC721/extensions/IERC721MetadataUpgradeable.sol";

contracts/interfaces/IERC721ReceiverUpgradeable.sol

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/IERC721Receiver.sol)
+
+pragma solidity ^0.8.0;
+
+import "../token/ERC721/IERC721ReceiverUpgradeable.sol";

contracts/interfaces/IERC721Upgradeable.sol

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/IERC721.sol)
+
+pragma solidity ^0.8.0;
+
+import "../token/ERC721/IERC721Upgradeable.sol";

contracts/interfaces/IERC777RecipientUpgradeable.sol

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/IERC777Recipient.sol)
+
+pragma solidity ^0.8.0;
+
+import "../token/ERC777/IERC777RecipientUpgradeable.sol";

contracts/interfaces/IERC777SenderUpgradeable.sol

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/IERC777Sender.sol)
+
+pragma solidity ^0.8.0;
+
+import "../token/ERC777/IERC777SenderUpgradeable.sol";

contracts/interfaces/IERC777Upgradeable.sol

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/IERC777.sol)
+
+pragma solidity ^0.8.0;
+
+import "../token/ERC777/IERC777Upgradeable.sol";

contracts/interfaces/README.adoc

@@ -0,0 +1,50 @@
+= Interfaces
+
+[.readme-notice]
+NOTE: This document is better viewed at https://docs.openzeppelin.com/contracts/api/interfaces
+
+== List of standardized interfaces
+These interfaces are available as `.sol` files, and also as compiler `.json` ABI files (through the npm package). These
+are useful to interact with third party contracts that implement them.
+
+- {IERC20}
+- {IERC20Metadata}
+- {IERC165}
+- {IERC721}
+- {IERC721Receiver}
+- {IERC721Enumerable}
+- {IERC721Metadata}
+- {IERC777}
+- {IERC777Recipient}
+- {IERC777Sender}
+- {IERC1155}
+- {IERC1155Receiver}
+- {IERC1155MetadataURI}
+- {IERC1271}
+- {IERC1363}
+- {IERC1820Implementer}
+- {IERC1820Registry}
+- {IERC2612}
+- {IERC2981}
+- {IERC3156FlashLender}
+- {IERC3156FlashBorrower}
+
+== Detailed ABI
+
+{{IERC1271}}
+
+{{IERC1363}}
+
+{{IERC1363Receiver}}
+
+{{IERC1820Implementer}}
+
+{{IERC1820Registry}}
+
+{{IERC2612}}
+
+{{IERC2981}}
+
+{{IERC3156FlashLender}}
+
+{{IERC3156FlashBorrower}}

contracts/interfaces/draft-IERC1822Upgradeable.sol

@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v4.5.0-rc.0) (interfaces/draft-IERC1822.sol)
+
+pragma solidity ^0.8.0;
+
+/**
+ * @dev ERC1822: Universal Upgradeable Proxy Standard (UUPS) documents a method for upgradeability through a simplified
+ * proxy whose upgrades are fully controlled by the current implementation.
+ */
+interface IERC1822ProxiableUpgradeable {
+    /**
+     * @dev Returns the storage slot that the proxiable contract assumes is being used to store the implementation
+     * address.
+     *
+     * IMPORTANT: A proxy pointing at a proxiable contract should not be considered proxiable itself, because this risks
+     * bricking a proxy that upgrades to it, by delegating to itself until out of gas. Thus it is critical that this
+     * function revert if invoked through a proxy.
+     */
+    function proxiableUUID() external view returns (bytes32);
+}

contracts/interfaces/draft-IERC2612Upgradeable.sol

@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (interfaces/draft-IERC2612.sol)
+
+pragma solidity ^0.8.0;
+
+import "../token/ERC20/extensions/draft-IERC20PermitUpgradeable.sol";
+
+interface IERC2612Upgradeable is IERC20PermitUpgradeable {}

contracts/metatx/ERC2771ContextUpgradeable.sol

@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v4.5.0-rc.0) (metatx/ERC2771Context.sol)
+
+pragma solidity ^0.8.9;
+
+import "../utils/ContextUpgradeable.sol";
+import "../proxy/utils/Initializable.sol";
+
+/**
+ * @dev Context variant with ERC2771 support.
+ */
+abstract contract ERC2771ContextUpgradeable is Initializable, ContextUpgradeable {
+    /// @custom:oz-upgrades-unsafe-allow state-variable-immutable
+    address private immutable _trustedForwarder;
+
+    /// @custom:oz-upgrades-unsafe-allow constructor
+    constructor(address trustedForwarder) {
+        _trustedForwarder = trustedForwarder;
+    }
+
+    function isTrustedForwarder(address forwarder) public view virtual returns (bool) {
+        return forwarder == _trustedForwarder;
+    }
+
+    function _msgSender() internal view virtual override returns (address sender) {
+        if (isTrustedForwarder(msg.sender)) {
+            // The assembly code is more direct than the Solidity version using `abi.decode`.
+            assembly {
+                sender := shr(96, calldataload(sub(calldatasize(), 20)))
+            }
+        } else {
+            return super._msgSender();
+        }
+    }
+
+    function _msgData() internal view virtual override returns (bytes calldata) {
+        if (isTrustedForwarder(msg.sender)) {
+            return msg.data[:msg.data.length - 20];
+        } else {
+            return super._msgData();
+        }
+    }
+    uint256[50] private __gap;
+}

contracts/metatx/MinimalForwarderUpgradeable.sol

@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v4.5.0-rc.0) (metatx/MinimalForwarder.sol)
+
+pragma solidity ^0.8.0;
+
+import "../utils/cryptography/ECDSAUpgradeable.sol";
+import "../utils/cryptography/draft-EIP712Upgradeable.sol";
+import "../proxy/utils/Initializable.sol";
+
+/**
+ * @dev Simple minimal forwarder to be used together with an ERC2771 compatible contract. See {ERC2771Context}.
+ */
+contract MinimalForwarderUpgradeable is Initializable, EIP712Upgradeable {
+    using ECDSAUpgradeable for bytes32;
+
+    struct ForwardRequest {
+        address from;
+        address to;
+        uint256 value;
+        uint256 gas;
+        uint256 nonce;
+        bytes data;
+    }
+
+    bytes32 private constant _TYPEHASH =
+        keccak256("ForwardRequest(address from,address to,uint256 value,uint256 gas,uint256 nonce,bytes data)");
+
+    mapping(address => uint256) private _nonces;
+
+    function __MinimalForwarder_init() internal onlyInitializing {
+        __EIP712_init_unchained("MinimalForwarder", "0.0.1");
+        __MinimalForwarder_init_unchained();
+    }
+
+    function __MinimalForwarder_init_unchained() internal onlyInitializing {}
+
+    function getNonce(address from) public view returns (uint256) {
+        return _nonces[from];
+    }
+
+    function verify(ForwardRequest calldata req, bytes calldata signature) public view returns (bool) {
+        address signer = _hashTypedDataV4(
+            keccak256(abi.encode(_TYPEHASH, req.from, req.to, req.value, req.gas, req.nonce, keccak256(req.data)))
+        ).recover(signature);
+        return _nonces[req.from] == req.nonce && signer == req.from;
+    }
+
+    function execute(ForwardRequest calldata req, bytes calldata signature)
+        public
+        payable
+        returns (bool, bytes memory)
+    {
+        require(verify(req, signature), "MinimalForwarder: signature does not match request");
+        _nonces[req.from] = req.nonce + 1;
+
+        (bool success, bytes memory returndata) = req.to.call{gas: req.gas, value: req.value}(
+            abi.encodePacked(req.data, req.from)
+        );
+
+        // Validate that the relayer has sent enough gas for the call.
+        // See https://ronan.eth.link/blog/ethereum-gas-dangers/
+        if (gasleft() <= req.gas / 63) {
+            // We explicitly trigger invalid opcode to consume all gas and bubble-up the effects, since
+            // neither revert or assert consume all gas since Solidity 0.8.0
+            // https://docs.soliditylang.org/en/v0.8.0/control-structures.html#panic-via-assert-and-error-via-require
+            assembly {
+                invalid()
+            }
+        }
+
+        return (success, returndata);
+    }
+    uint256[49] private __gap;
+}