Add Multicall module (#2608)

contracts/utils/Multicall.sol

@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import "./Address.sol";
+
+/**
+ * @dev Provides a function to batch together multiple calls in a single external call.
+ */
+abstract contract Multicall {
+    /**
+    * @dev Receives and executes a batch of function calls on this contract.
+    */
+    function multicall(bytes[] calldata data) external returns (bytes[] memory results) {
+        results = new bytes[](data.length);
+        for (uint i = 0; i < data.length; i++) {
+            results[i] = Address.functionDelegateCall(address(this), data[i]);
+        }
+        return results;
+    }
+}

contracts/utils/README.adoc

@@ -6,6 +6,7 @@ NOTE: This document is better viewed at https://docs.openzeppelin.com/contracts/
 Miscellaneous contracts and libraries containing utility functions you can use to improve security, work with new data types, or safely use low-level primitives.
 
 The {Address}, {Arrays} and {Strings} libraries provide more operations related to these native data types, while {SafeCast} adds ways to safely convert between the different signed and unsigned numeric types.
+{Multicall} provides a function to batch together multiple calls in a single external call.
 
 For new data types:
 
@@ -94,3 +95,5 @@ Note that, in all cases, accounts simply _declare_ their interfaces, but they ar
 {{Counters}}
 
 {{Strings}}
+
+{{Multicall}}