From 82306d2d9968dc48fd7fda1f07f04c4b383822dd Mon Sep 17 00:00:00 2001
From: Vectorized <webby1111@hotmail.com>
Date: Mon, 11 Jul 2022 06:48:53 +0000
Subject: [PATCH 1/4] Fix casting to bytes1 in v0.8.4

---
 contracts/mocks/ERC721ReceiverMock.sol | 22 ++++++++++++++++------
 hardhat.config.js                      |  2 +-
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/contracts/mocks/ERC721ReceiverMock.sol b/contracts/mocks/ERC721ReceiverMock.sol
index 212fed6b8..fd40b1403 100644
--- a/contracts/mocks/ERC721ReceiverMock.sol
+++ b/contracts/mocks/ERC721ReceiverMock.sol
@@ -34,18 +34,28 @@ contract ERC721ReceiverMock is ERC721A__IERC721Receiver {
         uint256 tokenId,
         bytes memory data
     ) public override returns (bytes4) {
-        // for testing reverts with a message from the receiver contract
-        if (bytes1(data) == 0x01) {
+        uint256 dataValue;
+        // In v0.8.4, we can't directly cast via `bytes1(data)`.
+        // This assembly allows us to do the casting.
+        assembly {
+            // If `data.length > 0`.
+            if mload(data) {
+                // Load the first byte of `data`.
+                dataValue := byte(0, mload(add(data, 0x20)))
+            }
+        }
+        // For testing reverts with a message from the receiver contract.
+        if (dataValue == 0x01) {
             revert('reverted in the receiver contract!');
         }
 
-        // for testing with the returned wrong value from the receiver contract
-        if (bytes1(data) == 0x02) {
+        // For testing with the returned wrong value from the receiver contract.
+        if (dataValue == 0x02) {
             return 0x0;
         }
 
-        // for testing the reentrancy protection
-        if (bytes1(data) == 0x03) {
+        // For testing the reentrancy protection.
+        if (dataValue == 0x03) {
             IERC721AMock(_erc721aMock).safeMint(address(this), 1);
         }
 
diff --git a/hardhat.config.js b/hardhat.config.js
index 53665221e..3efe779f3 100644
--- a/hardhat.config.js
+++ b/hardhat.config.js
@@ -14,7 +14,7 @@ if (process.env.REPORT_COVERAGE) {
  */
 module.exports = {
   solidity: {
-    version: '0.8.11',
+    version: '0.8.4',
     settings: {
       optimizer: {
         enabled: true,

From ab8251e29daee3b1d64a4440272f023bd1189084 Mon Sep 17 00:00:00 2001
From: Vectorized <webby1111@hotmail.com>
Date: Mon, 11 Jul 2022 06:52:37 +0000
Subject: [PATCH 2/4] Set back solc to v0.8.11

---
 hardhat.config.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hardhat.config.js b/hardhat.config.js
index 3efe779f3..53665221e 100644
--- a/hardhat.config.js
+++ b/hardhat.config.js
@@ -14,7 +14,7 @@ if (process.env.REPORT_COVERAGE) {
  */
 module.exports = {
   solidity: {
-    version: '0.8.4',
+    version: '0.8.11',
     settings: {
       optimizer: {
         enabled: true,

From 2b92777936a28bc91cd7ef02a954e455b6fe9b5a Mon Sep 17 00:00:00 2001
From: Vectorized <webby1111@hotmail.com>
Date: Mon, 11 Jul 2022 06:54:37 +0000
Subject: [PATCH 3/4] Fix comments

---
 contracts/mocks/ERC721ReceiverMock.sol | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/contracts/mocks/ERC721ReceiverMock.sol b/contracts/mocks/ERC721ReceiverMock.sol
index fd40b1403..dfc868975 100644
--- a/contracts/mocks/ERC721ReceiverMock.sol
+++ b/contracts/mocks/ERC721ReceiverMock.sol
@@ -40,10 +40,11 @@ contract ERC721ReceiverMock is ERC721A__IERC721Receiver {
         assembly {
             // If `data.length > 0`.
             if mload(data) {
-                // Load the first byte of `data`.
+                // Load the 0th byte of `data`.
                 dataValue := byte(0, mload(add(data, 0x20)))
             }
         }
+        
         // For testing reverts with a message from the receiver contract.
         if (dataValue == 0x01) {
             revert('reverted in the receiver contract!');

From e650cb3bc9e88e74f9325e9fae3cebc3048ce36a Mon Sep 17 00:00:00 2001
From: Vectorized <webby1111@hotmail.com>
Date: Tue, 12 Jul 2022 17:14:19 +0000
Subject: [PATCH 4/4] Change to normal Solidity cast

---
 contracts/mocks/ERC721ReceiverMock.sol | 11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

diff --git a/contracts/mocks/ERC721ReceiverMock.sol b/contracts/mocks/ERC721ReceiverMock.sol
index dfc868975..8ab1fed9f 100644
--- a/contracts/mocks/ERC721ReceiverMock.sol
+++ b/contracts/mocks/ERC721ReceiverMock.sol
@@ -34,16 +34,7 @@ contract ERC721ReceiverMock is ERC721A__IERC721Receiver {
         uint256 tokenId,
         bytes memory data
     ) public override returns (bytes4) {
-        uint256 dataValue;
-        // In v0.8.4, we can't directly cast via `bytes1(data)`.
-        // This assembly allows us to do the casting.
-        assembly {
-            // If `data.length > 0`.
-            if mload(data) {
-                // Load the 0th byte of `data`.
-                dataValue := byte(0, mload(add(data, 0x20)))
-            }
-        }
+        uint256 dataValue = data.length == 0 ? 0 : uint256(uint8(data[0]));
         
         // For testing reverts with a message from the receiver contract.
         if (dataValue == 0x01) {