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Remove the storage associated with decimals (#2502)

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* Removing the storage associated with decimals

* changelog entry

* changelog link to new issue number

* Update contracts/token/ERC20/ERC20.sol

Co-authored-by: Francisco Giordano <frangio.1@gmail.com>

* Update contracts/token/ERC20/ERC20.sol

Co-authored-by: Francisco Giordano <frangio.1@gmail.com>

* Update CHANGELOG.md

Co-authored-by: Francisco Giordano <frangio.1@gmail.com>

Co-authored-by: Francisco Giordano <frangio.1@gmail.com>
This commit is contained in:
Hadrien Croubois
2021-02-04 20:06:00 +01:00
committed by GitHub
parent ed7623273a
commit b840341a77
3 changed files with 15 additions and 21 deletions
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1
CHANGELOG.md
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@ -4,6 +4,7 @@
* 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))
## 3.4.0 (2021-02-02)

10
contracts/mocks/ERC20DecimalsMock.sol
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@ -5,7 +5,13 @@ pragma solidity ^0.8.0;
import "../token/ERC20/ERC20.sol";
contract ERC20DecimalsMock is ERC20 {
constructor (string memory name, string memory symbol, uint8 decimals) ERC20(name, symbol) {
_setupDecimals(decimals);
uint8 immutable private _decimals;
constructor (string memory name_, string memory symbol_, uint8 decimals_) ERC20(name_, symbol_) {
_decimals = decimals_;
}
function decimals() public view virtual override returns (uint8) {
return _decimals;
}
}

25
contracts/token/ERC20/ERC20.sol
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@ -38,13 +38,12 @@ contract ERC20 is Context, IERC20 {
string private _name;
string private _symbol;
uint8 private _decimals;
/**
* @dev Sets the values for {name} and {symbol}, initializes {decimals} with
* a default value of 18.
* @dev Sets the values for {name} and {symbol}.
*
* To select a different value for {decimals}, use {_setupDecimals}.
* The defaut value of {decimals} is 18. To select a different value for
* {decimals} you should overload it.
*
* All three of these values are immutable: they can only be set once during
* construction.
@ -52,7 +51,6 @@ contract ERC20 is Context, IERC20 {
constructor (string memory name_, string memory symbol_) {
_name = name_;
_symbol = symbol_;
_decimals = 18;
}
/**
@ -76,15 +74,15 @@ contract ERC20 is Context, IERC20 {
* be displayed to a user as `5,05` (`505 / 10 ** 2`).
*
* Tokens usually opt for a value of 18, imitating the relationship between
* Ether and Wei. This is the value {ERC20} uses, unless {_setupDecimals} is
* called.
* Ether and Wei. This is the value {ERC20} uses, unless this function is
* overloaded;
*
* NOTE: This information is only used for _display_ purposes: it in
* no way affects any of the arithmetic of the contract, including
* {IERC20-balanceOf} and {IERC20-transfer}.
*/
function decimals() public view virtual returns (uint8) {
return _decimals;
return 18;
}
/**
@ -283,17 +281,6 @@ contract ERC20 is Context, IERC20 {
emit Approval(owner, spender, amount);
}
/**
* @dev Sets {decimals} to a value other than the default one of 18.
*
* WARNING: This function should only be called from the constructor. Most
* applications that interact with token contracts will not expect
* {decimals} to ever change, and may work incorrectly if it does.
*/
function _setupDecimals(uint8 decimals_) internal virtual {
_decimals = decimals_;
}
/**
* @dev Hook that is called before any transfer of tokens. This includes
* minting and burning.