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Optimize implementation of ERC20Capped #2524

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Feb 24, 2021
Merged

Optimize implementation of ERC20Capped #2524

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b40bcbc
overload _mint in erc20capped instead of hooking to transfer: saves g…
Amxx Feb 15, 2021
070ce23
Update contracts/token/ERC20/ERC20Capped.sol
Amxx Feb 17, 2021
646b976
add changelog entry
Amxx Feb 18, 2021
5896678
edit documentation
frangio Feb 24, 2021
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1 change: 1 addition & 0 deletions CHANGELOG.md
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Expand Up @@ -14,6 +14,7 @@
* `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 reorganisation of the contract folder to improve clarity and discoverability. ([#2503](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2503))
* `ERC20Capped`: optimize gas usage of by enforcing te check directly in `_mint`. ([#2524](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2524))

### How to upgrade from 3.x

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15 changes: 4 additions & 11 deletions contracts/token/ERC20/extensions/ERC20Capped.sol
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Expand Up @@ -27,17 +27,10 @@ abstract contract ERC20Capped is ERC20 {
}

/**
* @dev See {ERC20-_beforeTokenTransfer}.
*
* Requirements:
*
* - minted tokens must not cause the total supply to go over the cap.
* @dev See {ERC20-_mint}.
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I edited the documentation to use this "See" format we've been useing so far.

*/
function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual override {
super._beforeTokenTransfer(from, to, amount);

if (from == address(0)) { // When minting tokens
require(totalSupply() + amount <= cap(), "ERC20Capped: cap exceeded");
}
function _mint(address account, uint256 amount) internal virtual override {
require(ERC20.totalSupply() + amount <= cap(), "ERC20Capped: cap exceeded");
super._mint(account, amount);
}
}