Merge upstream openzeppelin-contracts into upstream-patched

CHANGELOG.md

@@ -2,9 +2,20 @@
 
 ## Unreleased
 
-* `ERC20Votes`: add a new extension of the `ERC20` token with support for voting snapshots and delegation. This extension is compatible with Compound's `Comp` token interface. ([#2632](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2632))
+ * `ERC20Votes`: add a new extension of the `ERC20` token with support for voting snapshots and delegation. This extension is compatible with Compound's `Comp` token interface. ([#2632](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2632))
  * 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.
+
+ ### 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)
 

contracts/mocks/CountersImpl.sol

@@ -20,4 +20,8 @@ contract CountersImpl {
     function decrement() public {
         _counter.decrement();
     }
+
+    function reset() public {
+        _counter.reset();
+    }
 }

contracts/mocks/ERC3156Mock.sol → contracts/mocks/ERC20FlashMintMock.sol

@@ -3,7 +3,7 @@
 pragma solidity ^0.8.0;
 
 
-import "../token/ERC20/extensions/draft-ERC20FlashMint.sol";
+import "../token/ERC20/extensions/ERC20FlashMint.sol";
 
 contract ERC20FlashMintMock is ERC20FlashMint {
     constructor (

contracts/mocks/ERC20VotesMock.sol

@@ -3,7 +3,7 @@
 pragma solidity ^0.8.0;
 
 
-import "../token/ERC20/extensions/draft-ERC20Votes.sol";
+import "../token/ERC20/extensions/ERC20Votes.sol";
 
 contract ERC20VotesMock is ERC20Votes {
     constructor (

contracts/mocks/MathMock.sol

@@ -16,4 +16,8 @@ contract MathMock {
     function average(uint256 a, uint256 b) public pure returns (uint256) {
         return Math.average(a, b);
     }
+
+    function ceilDiv(uint256 a, uint256 b) public pure returns (uint256) {
+        return Math.ceilDiv(a, b);
+    }
 }

contracts/token/ERC1155/ERC1155.sol

@@ -187,7 +187,9 @@ contract ERC1155 is Context, ERC165, IERC1155, IERC1155MetadataURI {
 
         uint256 fromBalance = _balances[id][from];
         require(fromBalance >= amount, "ERC1155: insufficient balance for transfer");
+        unchecked {
             _balances[id][from] = fromBalance - amount;
+        }
         _balances[id][to] += amount;
 
         emit TransferSingle(operator, from, to, id, amount);
@@ -228,7 +230,9 @@ contract ERC1155 is Context, ERC165, IERC1155, IERC1155MetadataURI {
 
             uint256 fromBalance = _balances[id][from];
             require(fromBalance >= amount, "ERC1155: insufficient balance for transfer");
+            unchecked {
                 _balances[id][from] = fromBalance - amount;
+            }
             _balances[id][to] += amount;
         }
 
@@ -327,7 +331,9 @@ contract ERC1155 is Context, ERC165, IERC1155, IERC1155MetadataURI {
 
         uint256 accountBalance = _balances[id][account];
         require(accountBalance >= amount, "ERC1155: burn amount exceeds balance");
+        unchecked {
             _balances[id][account] = accountBalance - amount;
+        }
 
         emit TransferSingle(operator, account, address(0), id, amount);
     }
@@ -353,8 +359,10 @@ contract ERC1155 is Context, ERC165, IERC1155, IERC1155MetadataURI {
 
             uint256 accountBalance = _balances[id][account];
             require(accountBalance >= amount, "ERC1155: burn amount exceeds balance");
+            unchecked {
                 _balances[id][account] = accountBalance - amount;
             }
+        }
 
         emit TransferBatch(operator, account, address(0), ids, amounts);
     }

contracts/token/ERC20/ERC20.sol

@@ -150,7 +150,9 @@ contract ERC20 is Context, IERC20, IERC20Metadata {
 
         uint256 currentAllowance = _allowances[sender][_msgSender()];
         require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
+        unchecked {
             _approve(sender, _msgSender(), currentAllowance - amount);
+        }
 
         return true;
     }
@@ -189,7 +191,9 @@ contract ERC20 is Context, IERC20, IERC20Metadata {
     function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
         uint256 currentAllowance = _allowances[_msgSender()][spender];
         require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
+        unchecked {
             _approve(_msgSender(), spender, currentAllowance - subtractedValue);
+        }
 
         return true;
     }
@@ -216,7 +220,9 @@ contract ERC20 is Context, IERC20, IERC20Metadata {
 
         uint256 senderBalance = _balances[sender];
         require(senderBalance >= amount, "ERC20: transfer amount exceeds balance");
+        unchecked {
             _balances[sender] = senderBalance - amount;
+        }
         _balances[recipient] += amount;
 
         emit Transfer(sender, recipient, amount);
@@ -259,8 +265,10 @@ contract ERC20 is Context, IERC20, IERC20Metadata {
 
         uint256 accountBalance = _balances[account];
         require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
+        unchecked {
             _balances[account] = accountBalance - amount;
             _totalSupply -= amount;
+        }
 
         emit Transfer(account, address(0), amount);
     }

contracts/token/ERC20/extensions/ERC20Burnable.sol

@@ -34,7 +34,9 @@ abstract contract ERC20Burnable is Context, ERC20 {
     function burnFrom(address account, uint256 amount) public virtual {
         uint256 currentAllowance = allowance(account, _msgSender());
         require(currentAllowance >= amount, "ERC20: burn amount exceeds allowance");
+        unchecked {
             _approve(account, _msgSender(), currentAllowance - amount);
+        }
         _burn(account, amount);
     }
 }

contracts/token/ERC20/extensions/draft-ERC20Votes.sol → contracts/token/ERC20/extensions/ERC20Votes.sol

@@ -3,7 +3,7 @@
 pragma solidity ^0.8.0;
 
 import "./draft-ERC20Permit.sol";
-import "./draft-IERC20Votes.sol";
+import "./IERC20Votes.sol";
 import "../../../utils/math/Math.sol";
 import "../../../utils/math/SafeCast.sol";
 import "../../../utils/cryptography/ECDSA.sol";

contracts/token/ERC721/ERC721.sol

@@ -98,8 +98,9 @@ contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
     }
 
     /**
-     * @dev Base URI for computing {tokenURI}. Empty by default, can be overriden
-     * in child contracts.
+     * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each
+     * token will be the concatenation of the `baseURI` and the `tokenId`. Empty 
+     * by default, can be overriden in child contracts.
      */
     function _baseURI() internal view virtual returns (string memory) {
         return "";

contracts/token/ERC777/ERC777.sol

@@ -51,7 +51,7 @@ contract ERC777 is Context, IERC777, IERC20 {
     mapping(address => mapping(address => bool)) private _revokedDefaultOperators;
 
     // ERC20-allowances
-    mapping (address => mapping (address => uint256)) private _allowances;
+    mapping(address => mapping(address => uint256)) private _allowances;
 
     /**
      * @dev `defaultOperators` may be an empty array.
@@ -419,8 +419,10 @@ contract ERC777 is Context, IERC777, IERC20 {
         // Update state variables
         uint256 fromBalance = _balances[from];
         require(fromBalance >= amount, "ERC777: burn amount exceeds balance");
+        unchecked {
             _balances[from] = fromBalance - amount;
             _totalSupply -= amount;
+        }
 
         emit Burned(operator, from, amount, data, operatorData);
         emit Transfer(from, address(0), amount);
@@ -440,7 +442,9 @@ contract ERC777 is Context, IERC777, IERC20 {
 
         uint256 fromBalance = _balances[from];
         require(fromBalance >= amount, "ERC777: transfer amount exceeds balance");
+        unchecked {
             _balances[from] = fromBalance - amount;
+        }
         _balances[to] += amount;
 
         emit Sent(operator, from, to, amount, userData, operatorData);

contracts/utils/Counters.sol

@@ -5,7 +5,7 @@ pragma solidity ^0.8.0;
 /**
  * @title Counters
  * @author Matt Condon (@shrugs)
- * @dev Provides counters that can only be incremented or decremented by one. This can be used e.g. to track the number
+ * @dev Provides counters that can only be incremented, decremented or reset. This can be used e.g. to track the number
  * of elements in a mapping, issuing ERC721 ids, or counting request ids.
  *
  * Include with `using Counters for Counters.Counter;`
@@ -35,4 +35,8 @@ library Counters {
             counter._value = value - 1;
         }
     }
+
+    function reset(Counter storage counter) internal {
+        counter._value = 0;
+    }
 }

contracts/utils/README.adoc

@@ -10,7 +10,7 @@ The {Address}, {Arrays} and {Strings} libraries provide more operations related
 
 For new data types:
 
- * {Counters}: a simple way to get a counter that can only be incremented or decremented. Very useful for ID generation, counting contract activity, among others.
+ * {Counters}: a simple way to get a counter that can only be incremented, decremented or reset. Very useful for ID generation, counting contract activity, among others.
  * {EnumerableMap}: like Solidity's https://solidity.readthedocs.io/en/latest/types.html#mapping-types[`mapping`] type, but with key-value _enumeration_: this will let you know how many entries a mapping has, and iterate over them (which is not possible with `mapping`).
  * {EnumerableSet}: like {EnumerableMap}, but for https://en.wikipedia.org/wiki/Set_(abstract_data_type)[sets]. Can be used to store privileged accounts, issued IDs, etc.
 

contracts/utils/math/Math.sol

@@ -28,4 +28,15 @@ library Math {
         // (a + b) / 2 can overflow, so we distribute.
         return (a / 2) + (b / 2) + ((a % 2 + b % 2) / 2);
     }
+
+    /**
+     * @dev Returns the ceiling of the division of two numbers.
+     *
+     * This differs from standard division with `/` in that it rounds up instead
+     * of rounding down.
+     */
+    function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
+        // (a + b - 1) / b can overflow on addition, so we distribute.
+        return a / b + (a % b == 0 ? 0 : 1);
+    }
 }

test/utils/Counters.test.js

@@ -61,4 +61,24 @@ contract('Counters', function (accounts) {
       });
     });
   });
+
+  describe('reset', function () {
+    context('null counter', function () {
+      it('does not throw', async function () {
+        await this.counter.reset();
+        expect(await this.counter.current()).to.be.bignumber.equal('0');
+      });
+    });
+
+    context('non null counter', function () {
+      beforeEach(async function () {
+        await this.counter.increment();
+        expect(await this.counter.current()).to.be.bignumber.equal('1');
+      });
+      it('reset to 0', async function () {
+        await this.counter.reset();
+        expect(await this.counter.current()).to.be.bignumber.equal('0');
+      });
+    });
+  });
 });

test/utils/math/Math.test.js

-const { BN } = require('@openzeppelin/test-helpers');
-
+const { BN, constants } = require('@openzeppelin/test-helpers');
 const { expect } = require('chai');
+const { MAX_UINT256 } = constants;
 
 const MathMock = artifacts.require('MathMock');
 
@@ -55,4 +55,29 @@ contract('Math', function (accounts) {
       expect(await this.math.average(a, b)).to.be.bignumber.equal(bnAverage(a, b));
     });
   });
+
+  describe('ceilDiv', function () {
+    it('does not round up on exact division', async function () {
+      const a = new BN('10');
+      const b = new BN('5');
+      expect(await this.math.ceilDiv(a, b)).to.be.bignumber.equal('2');
+    });
+
+    it('rounds up on division with remainders', async function () {
+      const a = new BN('42');
+      const b = new BN('13');
+      expect(await this.math.ceilDiv(a, b)).to.be.bignumber.equal('4');
+    });
+
+    it('does not overflow', async function () {
+      const b = new BN('2');
+      const result = new BN('1').shln(255);
+      expect(await this.math.ceilDiv(MAX_UINT256, b)).to.be.bignumber.equal(result);
+    });
+
+    it('correctly computes max uint256 divided by 1', async function () {
+      const b = new BN('1');
+      expect(await this.math.ceilDiv(MAX_UINT256, b)).to.be.bignumber.equal(MAX_UINT256);
+    });
+  });
 });