Merge upstream master into patched/master

contracts/token/ERC1155/IERC1155Receiver.sol

@@ -10,17 +10,19 @@ import "../../utils/introspection/IERC165.sol";
  */
 interface IERC1155Receiver is IERC165 {
     /**
-        @dev Handles the receipt of a single ERC1155 token type. This function is
-        called at the end of a `safeTransferFrom` after the balance has been updated.
-        To accept the transfer, this must return
-        `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))`
-        (i.e. 0xf23a6e61, or its own function selector).
-        @param operator The address which initiated the transfer (i.e. msg.sender)
-        @param from The address which previously owned the token
-        @param id The ID of the token being transferred
-        @param value The amount of tokens being transferred
-        @param data Additional data with no specified format
-        @return `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))` if transfer is allowed
+     * @dev Handles the receipt of a single ERC1155 token type. This function is
+     * called at the end of a `safeTransferFrom` after the balance has been updated.
+     *
+     * NOTE: To accept the transfer, this must return
+     * `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))`
+     * (i.e. 0xf23a6e61, or its own function selector).
+     *
+     * @param operator The address which initiated the transfer (i.e. msg.sender)
+     * @param from The address which previously owned the token
+     * @param id The ID of the token being transferred
+     * @param value The amount of tokens being transferred
+     * @param data Additional data with no specified format
+     * @return `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))` if transfer is allowed
      */
     function onERC1155Received(
         address operator,
@@ -31,17 +33,20 @@ interface IERC1155Receiver is IERC165 {
     ) external returns (bytes4);
 
     /**
-        @dev Handles the receipt of a multiple ERC1155 token types. This function
-        is called at the end of a `safeBatchTransferFrom` after the balances have
-        been updated. To accept the transfer(s), this must return
-        `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))`
-        (i.e. 0xbc197c81, or its own function selector).
-        @param operator The address which initiated the batch transfer (i.e. msg.sender)
-        @param from The address which previously owned the token
-        @param ids An array containing ids of each token being transferred (order and length must match values array)
-        @param values An array containing amounts of each token being transferred (order and length must match ids array)
-        @param data Additional data with no specified format
-        @return `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))` if transfer is allowed
+     * @dev Handles the receipt of a multiple ERC1155 token types. This function
+     * is called at the end of a `safeBatchTransferFrom` after the balances have
+     * been updated.
+     *
+     * NOTE: To accept the transfer(s), this must return
+     * `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))`
+     * (i.e. 0xbc197c81, or its own function selector).
+     *
+     * @param operator The address which initiated the batch transfer (i.e. msg.sender)
+     * @param from The address which previously owned the token
+     * @param ids An array containing ids of each token being transferred (order and length must match values array)
+     * @param values An array containing amounts of each token being transferred (order and length must match ids array)
+     * @param data Additional data with no specified format
+     * @return `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))` if transfer is allowed
      */
     function onERC1155BatchReceived(
         address operator,

contracts/token/ERC1155/README.adoc

@@ -26,6 +26,8 @@ NOTE: This core set of contracts is designed to be unopinionated, allowing devel
 
 {{IERC1155Receiver}}
 
+{{ERC1155Receiver}}
+
 == Extensions
 
 {{ERC1155Pausable}}

contracts/token/ERC1155/utils/ERC1155Holder.sol

@@ -6,6 +6,11 @@ pragma solidity ^0.8.0;
 import "./ERC1155Receiver.sol";
 
 /**
+ * Simple implementation of `ERC1155Receiver` that will allow a contract to hold ERC1155 tokens.
+ *
+ * IMPORTANT: When inheriting this contract, you must include a way to use the received tokens, otherwise they will be
+ * stuck.
+ *
  * @dev _Available since v3.1._
  */
 contract ERC1155Holder is ERC1155Receiver {