Merge upstream openzeppelin-contracts into upstream-patched

CHANGELOG.md

@@ -20,6 +20,7 @@
 
 ## Unreleased
 
+ * Now supports both Solidity 0.6 and 0.7. Compiling with solc 0.7 will result in warnings. Install the `solc-0.7` tag to compile without warnings.
  * `Address`: added `functionStaticCall` and `functionDelegateCall`, similar to the existing `functionCall`. ([#2333](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2333))
  * `TimelockController`: added a contract to augment access control schemes with a delay. ([#2364](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2364))
  * `EnumerableSet`: added `Bytes32Set`, for sets of `bytes32`. ([#2395](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2395))

contracts/token/ERC1155/ERC1155.sol

@@ -237,7 +237,7 @@ contract ERC1155 is Context, ERC165, IERC1155, IERC1155MetadataURI {
      * Requirements:
      *
      * - `account` cannot be the zero address.
-     * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155Received} and return the
+     * - If `account` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155Received} and return the
      * acceptance magic value.
      */
     function _mint(address account, uint256 id, uint256 amount, bytes memory data) internal virtual {