Remove utils/Counters.sol (#4289)

Co-authored-by: Francisco Giordano <fg@frang.io>

contracts/utils/Counters.sol

@@ -1,43 +0,0 @@
-// SPDX-License-Identifier: MIT
-// OpenZeppelin Contracts v4.4.1 (utils/Counters.sol)
-
-pragma solidity ^0.8.19;
-
-/**
- * @title Counters
- * @author Matt Condon (@shrugs)
- * @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;`
- */
-library Counters {
-    struct Counter {
-        // This variable should never be directly accessed by users of the library: interactions must be restricted to
-        // the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add
-        // this feature: see https://github.com/ethereum/solidity/issues/4637
-        uint256 _value; // default: 0
-    }
-
-    function current(Counter storage counter) internal view returns (uint256) {
-        return counter._value;
-    }
-
-    function increment(Counter storage counter) internal {
-        unchecked {
-            counter._value += 1;
-        }
-    }
-
-    function decrement(Counter storage counter) internal {
-        uint256 value = counter._value;
-        require(value > 0, "Counter: decrement overflow");
-        unchecked {
-            counter._value = value - 1;
-        }
-    }
-
-    function reset(Counter storage counter) internal {
-        counter._value = 0;
-    }
-}

contracts/utils/Nonces.sol

@@ -1,21 +1,17 @@
 // SPDX-License-Identifier: MIT
 pragma solidity ^0.8.19;
 
-import "./Counters.sol";
-
 /**
  * @dev Provides tracking nonces for addresses. Nonces will only increment.
  */
 abstract contract Nonces {
-    using Counters for Counters.Counter;
-
-    mapping(address => Counters.Counter) private _nonces;
+    mapping(address => uint256) private _nonces;
 
     /**
      * @dev Returns an address nonce.
      */
     function nonces(address owner) public view virtual returns (uint256) {
-        return _nonces[owner].current();
+        return _nonces[owner];
     }
 
     /**
@@ -23,9 +19,12 @@ abstract contract Nonces {
      *
      * Returns the current value and increments nonce.
      */
-    function _useNonce(address owner) internal virtual returns (uint256 current) {
-        Counters.Counter storage nonce = _nonces[owner];
-        current = nonce.current();
-        nonce.increment();
+    function _useNonce(address owner) internal virtual returns (uint256) {
+        // For each account, the nonce has an initial value of 0, can only be incremented by one, and cannot be
+        // decremented or reset. This guarantees that the nonce never overflows.
+        unchecked {
+            // It is important to do x++ and not ++x here.
+            return _nonces[owner]++;
+        }
     }
 }

contracts/utils/README.adoc

@@ -10,7 +10,6 @@ The {Address}, {Arrays}, {Base64} and {Strings} libraries provide more operation
 
 For new data types:
 
- * {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.
 
@@ -75,8 +74,6 @@ Ethereum contracts have no native concept of an interface, so applications must
 
 {{Base64}}
 
-{{Counters}}
-
 {{Strings}}
 
 {{ShortStrings}}