Port to Solidity 0.8.21 passes 3 tests

src/Constants.sol

@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: UNLICENSED
-pragma solidity =0.7.6;
+//pragma solidity =0.7.6;
+pragma solidity >=0.8.0;
 pragma abicoder v2;
 
 import "@uniswap/v3-core/contracts/interfaces/IUniswapV3Factory.sol";

src/Dexorder.sol

@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: UNLICENSED
-pragma solidity =0.7.6;
+// pragma solidity =0.7.6;
+pragma solidity >=0.8.0;
 import "./OrderLib.sol";
 import "./Vault.sol";
 pragma abicoder v2;

src/Factory.sol

@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: UNLICENSED
-pragma solidity =0.7.6;
+//pragma solidity =0.7.6;
+pragma solidity >=0.8.0;
 
 import "./VaultDeployer.sol";
 pragma abicoder v2;

src/MockERC20.sol

@@ -1,15 +1,22 @@
-pragma solidity =0.7.6;
+//pragma solidity =0.7.6;
+pragma solidity >=0.8.0;
 import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
 
 
 contract MockERC20 is ERC20 {
 
-    constructor(string memory name, string memory symbol, uint8 decimals)
+    uint8 private _decimals;
+
+    constructor(string memory name, string memory symbol, uint8 decimals_)
     ERC20(name, symbol)
     {
-        _setupDecimals(decimals);
+        // _setupDecimals(decimals);
+        _decimals = decimals_;
     }
 
+    function decimals() public view override returns (uint8) {
+        return _decimals;
+    }
 
     function mint(address account, uint256 amount) external {
         _mint(account, amount);

src/OrderLib.sol

@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: UNLICENSED
-pragma solidity =0.7.6;
+// pragma solidity =0.7.6;
+pragma solidity >=0.8.0;
 pragma abicoder v2;
 
 import "@uniswap/v3-core/contracts/interfaces/IUniswapV3Pool.sol";

src/QueryHelper.sol

@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: UNLICENSED
-pragma solidity =0.7.6;
+//pragma solidity =0.7.6;
+pragma solidity >=0.8.0;
 pragma abicoder v2;
 
 import "v3-core/contracts/interfaces/IUniswapV3Pool.sol";

src/UniswapSwapper.sol

@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: UNLICENSED
-pragma solidity =0.7.6;
+//pragma solidity =0.7.6;
+pragma solidity >=0.8.0;
 pragma abicoder v2;
 
 import "./Constants.sol";

src/Util.sol

@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: UNLICENSED
-pragma solidity =0.7.6;
+//pragma solidity =0.7.6;
+pragma solidity >=0.8.0;
 pragma abicoder v2;
 
 library Util {

src/Vault.sol

@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: UNLICENSED
-pragma solidity =0.7.6;
+//pragma solidity =0.7.6;
+pragma solidity >=0.8.0;
 pragma abicoder v2;
 
 import "./Constants.sol";
@@ -31,7 +32,7 @@ contract Vault {
     }
 
     function withdraw(uint256 amount) public {
-        _withdrawNative(msg.sender, amount);
+        _withdrawNative(payable(msg.sender), amount);
     }
 
     function withdrawTo(address payable recipient, uint256 amount) public {

src/VaultAddress.sol

@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: UNLICENSED
-pragma solidity =0.7.6;
+//pragma solidity =0.7.6;
+pragma solidity >=0.8.0;
 pragma abicoder v2;
 
 import "./Constants.sol";
@@ -10,7 +11,7 @@ library VaultAddress {
     // keccak-256 hash of the Vault's bytecode (not the deployed bytecode but the initialization bytecode)
     // can paste into:
     // https://emn178.github.io/online-tools/keccak_256.html
-    bytes32 internal constant VAULT_INIT_CODE_HASH = 0xbc5f4b6509a7bbf6d9bcbd2b24c599e63143e9ba77aebe3d9486f1cbfcbda9ea;
+    bytes32 internal constant VAULT_INIT_CODE_HASH = 0x060e1878e07cde3b1fe03b6a8929c62c502510ed5dda30b278951f11dfc03490;
 
     // the contract being constructed must not have any constructor arguments or the determinism will be broken.  instead, use a callback to
     // get construction arguments
@@ -22,7 +23,7 @@ library VaultAddress {
 
     function computeAddress(address factory, address owner, uint8 num) internal pure returns (address vault) {
         bytes32 salt = keccak256(abi.encodePacked(owner,num));
-        vault = address(
+        vault = address(uint160(
             uint256(
                 keccak256(
                     abi.encodePacked(
@@ -33,6 +34,6 @@ library VaultAddress {
                     )
                 )
             )
-        );
+        ));
     }
 }

src/VaultDeployer.sol

@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: UNLICENSED
-pragma solidity =0.7.6;
+//pragma solidity =0.7.6;
+pragma solidity >=0.8.0;
 
 import "./Vault.sol";
 pragma abicoder v2;
@@ -32,7 +33,7 @@ contract VaultDeployer {
 
     function _deployVault(address owner, uint8 num) internal returns (address payable vault) {
         parameters = Parameters(owner);
-        vault = address(new Vault{salt: keccak256(abi.encodePacked(owner,num))}());
+        vault = payable(address(new Vault{salt: keccak256(abi.encodePacked(owner,num))}()));
         delete parameters;
         emit VaultCreated( owner, num );
     }

src/interface/IVaultDeployer.sol

@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: UNLICENSED
-pragma solidity =0.7.6;
+//pragma solidity =0.7.6;
+pragma solidity >=0.8.0;
 pragma abicoder v2;
 
 interface IVaultDeployer {