From b59b1b5cea066a74467aa80525f6c7e9dce2301b Mon Sep 17 00:00:00 2001
From: saucepoint <saucepoint@protonmail.com>
Date: Fri, 2 Aug 2024 22:02:45 -0400
Subject: [PATCH 1/8] WOOF WOOF WOOF BARK BARK WOOF BARK

---
 ...tionManager_multicall_initialize_mint.snap |  2 +-
 .forge-snapshots/PositionManager_permit.snap  |  2 +-
 ...PositionManager_permit_secondPosition.snap |  2 +-
 .../PositionManager_permit_twice.snap         |  2 +-
 remappings.txt                                |  1 -
 src/base/EIP712.sol                           | 48 +++++++++++++++++++
 src/base/ERC721Permit.sol                     |  9 +---
 src/interfaces/IEIP712.sol                    |  6 +++
 src/interfaces/IERC721Permit.sol              |  4 --
 test/ERC721Permit.t.sol                       |  2 +-
 test/position-managers/Permit.t.sol           |  2 +-
 11 files changed, 62 insertions(+), 18 deletions(-)
 create mode 100644 src/base/EIP712.sol
 create mode 100644 src/interfaces/IEIP712.sol

diff --git a/.forge-snapshots/PositionManager_multicall_initialize_mint.snap b/.forge-snapshots/PositionManager_multicall_initialize_mint.snap
index 2f927ade..15fd1f72 100644
--- a/.forge-snapshots/PositionManager_multicall_initialize_mint.snap
+++ b/.forge-snapshots/PositionManager_multicall_initialize_mint.snap
@@ -1 +1 @@
-416516
\ No newline at end of file
+416538
\ No newline at end of file
diff --git a/.forge-snapshots/PositionManager_permit.snap b/.forge-snapshots/PositionManager_permit.snap
index b2faa7cc..20d48590 100644
--- a/.forge-snapshots/PositionManager_permit.snap
+++ b/.forge-snapshots/PositionManager_permit.snap
@@ -1 +1 @@
-79585
\ No newline at end of file
+79660
\ No newline at end of file
diff --git a/.forge-snapshots/PositionManager_permit_secondPosition.snap b/.forge-snapshots/PositionManager_permit_secondPosition.snap
index 60f10b03..5a205f6d 100644
--- a/.forge-snapshots/PositionManager_permit_secondPosition.snap
+++ b/.forge-snapshots/PositionManager_permit_secondPosition.snap
@@ -1 +1 @@
-62497
\ No newline at end of file
+62572
\ No newline at end of file
diff --git a/.forge-snapshots/PositionManager_permit_twice.snap b/.forge-snapshots/PositionManager_permit_twice.snap
index 3df69310..660ed1ad 100644
--- a/.forge-snapshots/PositionManager_permit_twice.snap
+++ b/.forge-snapshots/PositionManager_permit_twice.snap
@@ -1 +1 @@
-45397
\ No newline at end of file
+45472
\ No newline at end of file
diff --git a/remappings.txt b/remappings.txt
index c7951f83..e7868fe9 100644
--- a/remappings.txt
+++ b/remappings.txt
@@ -1,5 +1,4 @@
 @uniswap/v4-core/=lib/v4-core/
-@openzeppelin/=lib/v4-core/lib/openzeppelin-contracts/
 forge-gas-snapshot/=lib/v4-core/lib/forge-gas-snapshot/src/
 ds-test/=lib/v4-core/lib/forge-std/lib/ds-test/src/
 forge-std/=lib/v4-core/lib/forge-std/src/
diff --git a/src/base/EIP712.sol b/src/base/EIP712.sol
new file mode 100644
index 00000000..05fe9ae0
--- /dev/null
+++ b/src/base/EIP712.sol
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.20;
+
+import {IEIP712} from "../interfaces/IEIP712.sol";
+
+/// @notice Generic EIP712 implementation
+/// @dev Maintains cross-chain replay protection in the event of a fork
+/// @dev Reference: https://github.com/Uniswap/permit2/blob/main/src/EIP712.sol
+/// @dev Reference: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/cryptography/EIP712.sol
+contract EIP712 is IEIP712 {
+    // Cache the domain separator as an immutable value, but also store the chain id that it
+    // corresponds to, in order to invalidate the cached domain separator if the chain id changes.
+    bytes32 private immutable _CACHED_DOMAIN_SEPARATOR;
+    uint256 private immutable _CACHED_CHAIN_ID;
+    address private immutable _CACHED_THIS;
+    bytes32 private immutable _HASHED_NAME;
+    bytes32 private immutable _HASHED_VERSION;
+
+    bytes32 private constant _TYPE_HASH =
+        keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)");
+
+    constructor(string memory name, string memory version) {
+        _HASHED_NAME = keccak256(bytes(name));
+        _HASHED_VERSION = keccak256(bytes(version));
+
+        _CACHED_CHAIN_ID = block.chainid;
+        _CACHED_DOMAIN_SEPARATOR = _buildDomainSeparator();
+        _CACHED_THIS = address(this);
+    }
+
+    /// @notice Returns the domain separator for the current chain.
+    /// @dev Uses cached version if chainid and address are unchanged from construction.
+    function DOMAIN_SEPARATOR() public view override returns (bytes32) {
+        return address(this) == _CACHED_THIS && block.chainid == _CACHED_CHAIN_ID
+            ? _CACHED_DOMAIN_SEPARATOR
+            : _buildDomainSeparator();
+    }
+
+    /// @notice Builds a domain separator using the current chainId and contract address.
+    function _buildDomainSeparator() private view returns (bytes32) {
+        return keccak256(abi.encode(_TYPE_HASH, _HASHED_NAME, _HASHED_VERSION, block.chainid, address(this)));
+    }
+
+    /// @notice Creates an EIP-712 typed data hash
+    function _hashTypedData(bytes32 dataHash) internal view returns (bytes32) {
+        return keccak256(abi.encodePacked("\x19\x01", DOMAIN_SEPARATOR(), dataHash));
+    }
+}
diff --git a/src/base/ERC721Permit.sol b/src/base/ERC721Permit.sol
index 7a4acc4d..316068db 100644
--- a/src/base/ERC721Permit.sol
+++ b/src/base/ERC721Permit.sol
@@ -3,7 +3,7 @@ pragma solidity ^0.8.24;
 
 import {IERC721} from "forge-std/interfaces/IERC721.sol";
 import {ERC721} from "solmate/src/tokens/ERC721.sol";
-import {EIP712} from "@openzeppelin/contracts/utils/cryptography/EIP712.sol";
+import {EIP712} from "./EIP712.sol";
 import {ERC721PermitHashLibrary} from "../libraries/ERC721PermitHash.sol";
 import {SignatureVerification} from "permit2/src/libraries/SignatureVerification.sol";
 
@@ -21,11 +21,6 @@ abstract contract ERC721Permit is ERC721, IERC721Permit, EIP712, UnorderedNonce
         EIP712(name_, version_)
     {}
 
-    /// @inheritdoc IERC721Permit
-    function DOMAIN_SEPARATOR() external view returns (bytes32) {
-        return _domainSeparatorV4();
-    }
-
     /// @inheritdoc IERC721Permit
     function permit(address spender, uint256 tokenId, uint256 deadline, uint256 nonce, bytes calldata signature)
         external
@@ -37,7 +32,7 @@ abstract contract ERC721Permit is ERC721, IERC721Permit, EIP712, UnorderedNonce
         if (spender == owner) revert NoSelfPermit();
 
         bytes32 hash = ERC721PermitHashLibrary.hash(spender, tokenId, nonce, deadline);
-        signature.verify(_hashTypedDataV4(hash), owner);
+        signature.verify(_hashTypedData(hash), owner);
 
         _useUnorderedNonce(owner, nonce);
         _approve(owner, spender, tokenId);
diff --git a/src/interfaces/IEIP712.sol b/src/interfaces/IEIP712.sol
new file mode 100644
index 00000000..355c443f
--- /dev/null
+++ b/src/interfaces/IEIP712.sol
@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.0;
+
+interface IEIP712 {
+    function DOMAIN_SEPARATOR() external view returns (bytes32);
+}
diff --git a/src/interfaces/IERC721Permit.sol b/src/interfaces/IERC721Permit.sol
index 646c1af0..29a6fe2a 100644
--- a/src/interfaces/IERC721Permit.sol
+++ b/src/interfaces/IERC721Permit.sol
@@ -8,10 +8,6 @@ interface IERC721Permit {
     error NoSelfPermit();
     error Unauthorized();
 
-    /// @notice The domain separator used in the permit signature
-    /// @return The domain seperator used in encoding of permit signature
-    function DOMAIN_SEPARATOR() external view returns (bytes32);
-
     /// @notice Approve of a specific token ID for spending by spender via signature
     /// @param spender The account that is being approved
     /// @param tokenId The ID of the token that is being approved for spending
diff --git a/test/ERC721Permit.t.sol b/test/ERC721Permit.t.sol
index d7126223..d2a26434 100644
--- a/test/ERC721Permit.t.sol
+++ b/test/ERC721Permit.t.sol
@@ -69,7 +69,7 @@ contract ERC721PermitTest is Test {
 
     function test_domainSeparator() public view {
         assertEq(
-            IERC721Permit(address(erc721Permit)).DOMAIN_SEPARATOR(),
+            erc721Permit.DOMAIN_SEPARATOR(),
             keccak256(
                 abi.encode(
                     keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
diff --git a/test/position-managers/Permit.t.sol b/test/position-managers/Permit.t.sol
index 7da608a2..01655e38 100644
--- a/test/position-managers/Permit.t.sol
+++ b/test/position-managers/Permit.t.sol
@@ -60,7 +60,7 @@ contract PermitTest is Test, PosmTestSetup {
 
     function test_domainSeparator() public view {
         assertEq(
-            IERC721Permit(address(lpm)).DOMAIN_SEPARATOR(),
+            ERC721Permit(address(lpm)).DOMAIN_SEPARATOR(),
             keccak256(
                 abi.encode(
                     keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),

From 4cd765a7c9399ab6d935ab59509df8d032e3c974 Mon Sep 17 00:00:00 2001
From: saucepoint <saucepoint@protonmail.com>
Date: Fri, 2 Aug 2024 23:55:13 -0400
Subject: [PATCH 2/8] remove address(this) check

---
 .forge-snapshots/PositionManager_permit.snap                | 2 +-
 .forge-snapshots/PositionManager_permit_secondPosition.snap | 2 +-
 .forge-snapshots/PositionManager_permit_twice.snap          | 2 +-
 src/base/EIP712.sol                                         | 4 +---
 4 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/.forge-snapshots/PositionManager_permit.snap b/.forge-snapshots/PositionManager_permit.snap
index 20d48590..a03aeb87 100644
--- a/.forge-snapshots/PositionManager_permit.snap
+++ b/.forge-snapshots/PositionManager_permit.snap
@@ -1 +1 @@
-79660
\ No newline at end of file
+79624
\ No newline at end of file
diff --git a/.forge-snapshots/PositionManager_permit_secondPosition.snap b/.forge-snapshots/PositionManager_permit_secondPosition.snap
index 5a205f6d..b08d0231 100644
--- a/.forge-snapshots/PositionManager_permit_secondPosition.snap
+++ b/.forge-snapshots/PositionManager_permit_secondPosition.snap
@@ -1 +1 @@
-62572
\ No newline at end of file
+62536
\ No newline at end of file
diff --git a/.forge-snapshots/PositionManager_permit_twice.snap b/.forge-snapshots/PositionManager_permit_twice.snap
index 660ed1ad..6c9b3ad3 100644
--- a/.forge-snapshots/PositionManager_permit_twice.snap
+++ b/.forge-snapshots/PositionManager_permit_twice.snap
@@ -1 +1 @@
-45472
\ No newline at end of file
+45436
\ No newline at end of file
diff --git a/src/base/EIP712.sol b/src/base/EIP712.sol
index 05fe9ae0..82ddff0e 100644
--- a/src/base/EIP712.sol
+++ b/src/base/EIP712.sol
@@ -12,7 +12,6 @@ contract EIP712 is IEIP712 {
     // corresponds to, in order to invalidate the cached domain separator if the chain id changes.
     bytes32 private immutable _CACHED_DOMAIN_SEPARATOR;
     uint256 private immutable _CACHED_CHAIN_ID;
-    address private immutable _CACHED_THIS;
     bytes32 private immutable _HASHED_NAME;
     bytes32 private immutable _HASHED_VERSION;
 
@@ -25,13 +24,12 @@ contract EIP712 is IEIP712 {
 
         _CACHED_CHAIN_ID = block.chainid;
         _CACHED_DOMAIN_SEPARATOR = _buildDomainSeparator();
-        _CACHED_THIS = address(this);
     }
 
     /// @notice Returns the domain separator for the current chain.
     /// @dev Uses cached version if chainid and address are unchanged from construction.
     function DOMAIN_SEPARATOR() public view override returns (bytes32) {
-        return address(this) == _CACHED_THIS && block.chainid == _CACHED_CHAIN_ID
+        return block.chainid == _CACHED_CHAIN_ID
             ? _CACHED_DOMAIN_SEPARATOR
             : _buildDomainSeparator();
     }

From cd8b7605a6eb8b9480fdc1e76b353de85692e87d Mon Sep 17 00:00:00 2001
From: saucepoint <saucepoint@protonmail.com>
Date: Fri, 2 Aug 2024 23:57:09 -0400
Subject: [PATCH 3/8] forge fmt

---
 src/base/EIP712.sol | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/src/base/EIP712.sol b/src/base/EIP712.sol
index 82ddff0e..73f5b636 100644
--- a/src/base/EIP712.sol
+++ b/src/base/EIP712.sol
@@ -29,9 +29,7 @@ contract EIP712 is IEIP712 {
     /// @notice Returns the domain separator for the current chain.
     /// @dev Uses cached version if chainid and address are unchanged from construction.
     function DOMAIN_SEPARATOR() public view override returns (bytes32) {
-        return block.chainid == _CACHED_CHAIN_ID
-            ? _CACHED_DOMAIN_SEPARATOR
-            : _buildDomainSeparator();
+        return block.chainid == _CACHED_CHAIN_ID ? _CACHED_DOMAIN_SEPARATOR : _buildDomainSeparator();
     }
 
     /// @notice Builds a domain separator using the current chainId and contract address.

From 9419e44ec4c8cc17e858362ee1ff7ef750bf3ad9 Mon Sep 17 00:00:00 2001
From: saucepoint <saucepoint@protonmail.com>
Date: Sat, 3 Aug 2024 00:15:28 -0400
Subject: [PATCH 4/8] discard version from EIP712

---
 .forge-snapshots/PositionManager_permit.snap              | 2 +-
 .../PositionManager_permit_secondPosition.snap            | 2 +-
 .forge-snapshots/PositionManager_permit_twice.snap        | 2 +-
 src/PositionManager.sol                                   | 2 +-
 src/base/EIP712.sol                                       | 8 +++-----
 src/base/ERC721Permit.sol                                 | 5 +----
 test/ERC721Permit.t.sol                                   | 6 ++----
 test/mocks/MockERC721Permit.sol                           | 2 +-
 test/position-managers/Permit.t.sol                       | 3 +--
 9 files changed, 12 insertions(+), 20 deletions(-)

diff --git a/.forge-snapshots/PositionManager_permit.snap b/.forge-snapshots/PositionManager_permit.snap
index a03aeb87..c3bc0823 100644
--- a/.forge-snapshots/PositionManager_permit.snap
+++ b/.forge-snapshots/PositionManager_permit.snap
@@ -1 +1 @@
-79624
\ No newline at end of file
+79636
\ No newline at end of file
diff --git a/.forge-snapshots/PositionManager_permit_secondPosition.snap b/.forge-snapshots/PositionManager_permit_secondPosition.snap
index b08d0231..fa2386f9 100644
--- a/.forge-snapshots/PositionManager_permit_secondPosition.snap
+++ b/.forge-snapshots/PositionManager_permit_secondPosition.snap
@@ -1 +1 @@
-62536
\ No newline at end of file
+62524
\ No newline at end of file
diff --git a/.forge-snapshots/PositionManager_permit_twice.snap b/.forge-snapshots/PositionManager_permit_twice.snap
index 6c9b3ad3..7cfd8d74 100644
--- a/.forge-snapshots/PositionManager_permit_twice.snap
+++ b/.forge-snapshots/PositionManager_permit_twice.snap
@@ -1 +1 @@
-45436
\ No newline at end of file
+45412
\ No newline at end of file
diff --git a/src/PositionManager.sol b/src/PositionManager.sol
index 88873384..e9e1a4c0 100644
--- a/src/PositionManager.sol
+++ b/src/PositionManager.sol
@@ -60,7 +60,7 @@ contract PositionManager is
     constructor(IPoolManager _poolManager, IAllowanceTransfer _permit2)
         BaseActionsRouter(_poolManager)
         Permit2Forwarder(_permit2)
-        ERC721Permit("Uniswap V4 Positions NFT", "UNI-V4-POSM", "1")
+        ERC721Permit("Uniswap V4 Positions NFT", "UNI-V4-POSM")
     {}
 
     /// @notice Reverts if the deadline has passed
diff --git a/src/base/EIP712.sol b/src/base/EIP712.sol
index 73f5b636..a4074350 100644
--- a/src/base/EIP712.sol
+++ b/src/base/EIP712.sol
@@ -13,14 +13,12 @@ contract EIP712 is IEIP712 {
     bytes32 private immutable _CACHED_DOMAIN_SEPARATOR;
     uint256 private immutable _CACHED_CHAIN_ID;
     bytes32 private immutable _HASHED_NAME;
-    bytes32 private immutable _HASHED_VERSION;
 
     bytes32 private constant _TYPE_HASH =
-        keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)");
+        keccak256("EIP712Domain(string name,uint256 chainId,address verifyingContract)");
 
-    constructor(string memory name, string memory version) {
+    constructor(string memory name) {
         _HASHED_NAME = keccak256(bytes(name));
-        _HASHED_VERSION = keccak256(bytes(version));
 
         _CACHED_CHAIN_ID = block.chainid;
         _CACHED_DOMAIN_SEPARATOR = _buildDomainSeparator();
@@ -34,7 +32,7 @@ contract EIP712 is IEIP712 {
 
     /// @notice Builds a domain separator using the current chainId and contract address.
     function _buildDomainSeparator() private view returns (bytes32) {
-        return keccak256(abi.encode(_TYPE_HASH, _HASHED_NAME, _HASHED_VERSION, block.chainid, address(this)));
+        return keccak256(abi.encode(_TYPE_HASH, _HASHED_NAME, block.chainid, address(this)));
     }
 
     /// @notice Creates an EIP-712 typed data hash
diff --git a/src/base/ERC721Permit.sol b/src/base/ERC721Permit.sol
index 316068db..1605b79c 100644
--- a/src/base/ERC721Permit.sol
+++ b/src/base/ERC721Permit.sol
@@ -16,10 +16,7 @@ abstract contract ERC721Permit is ERC721, IERC721Permit, EIP712, UnorderedNonce
     using SignatureVerification for bytes;
 
     /// @notice Computes the nameHash and versionHash
-    constructor(string memory name_, string memory symbol_, string memory version_)
-        ERC721(name_, symbol_)
-        EIP712(name_, version_)
-    {}
+    constructor(string memory name_, string memory symbol_) ERC721(name_, symbol_) EIP712(name_) {}
 
     /// @inheritdoc IERC721Permit
     function permit(address spender, uint256 tokenId, uint256 deadline, uint256 nonce, bytes calldata signature)
diff --git a/test/ERC721Permit.t.sol b/test/ERC721Permit.t.sol
index d2a26434..4048ad37 100644
--- a/test/ERC721Permit.t.sol
+++ b/test/ERC721Permit.t.sol
@@ -19,13 +19,12 @@ contract ERC721PermitTest is Test {
 
     string constant name = "Mock ERC721Permit";
     string constant symbol = "MOCK721";
-    string constant version = "1";
 
     function setUp() public {
         (alice, alicePK) = makeAddrAndKey("ALICE");
         (bob, bobPK) = makeAddrAndKey("BOB");
 
-        erc721Permit = new MockERC721Permit(name, symbol, version);
+        erc721Permit = new MockERC721Permit(name, symbol);
     }
 
     // --- Test the overriden approval ---
@@ -72,9 +71,8 @@ contract ERC721PermitTest is Test {
             erc721Permit.DOMAIN_SEPARATOR(),
             keccak256(
                 abi.encode(
-                    keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
+                    keccak256("EIP712Domain(string name,uint256 chainId,address verifyingContract)"),
                     keccak256(bytes(name)),
-                    keccak256(bytes(version)),
                     block.chainid,
                     address(erc721Permit)
                 )
diff --git a/test/mocks/MockERC721Permit.sol b/test/mocks/MockERC721Permit.sol
index d6e82a3e..ba1c732d 100644
--- a/test/mocks/MockERC721Permit.sol
+++ b/test/mocks/MockERC721Permit.sol
@@ -6,7 +6,7 @@ import {ERC721Permit} from "../../src/base/ERC721Permit.sol";
 contract MockERC721Permit is ERC721Permit {
     uint256 public lastTokenId;
 
-    constructor(string memory name, string memory symbol, string memory version) ERC721Permit(name, symbol, version) {}
+    constructor(string memory name, string memory symbol) ERC721Permit(name, symbol) {}
 
     function tokenURI(uint256) public pure override returns (string memory) {
         return "";
diff --git a/test/position-managers/Permit.t.sol b/test/position-managers/Permit.t.sol
index 01655e38..91a22a25 100644
--- a/test/position-managers/Permit.t.sol
+++ b/test/position-managers/Permit.t.sol
@@ -63,9 +63,8 @@ contract PermitTest is Test, PosmTestSetup {
             ERC721Permit(address(lpm)).DOMAIN_SEPARATOR(),
             keccak256(
                 abi.encode(
-                    keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
+                    keccak256("EIP712Domain(string name,uint256 chainId,address verifyingContract)"),
                     keccak256("Uniswap V4 Positions NFT"), // storage is private on EIP712.sol so we need to hardcode these
-                    keccak256("1"),
                     block.chainid,
                     address(lpm)
                 )

From 27d394e70679e2f05406e91bec3951f2a40c816f Mon Sep 17 00:00:00 2001
From: saucepoint <98790946+saucepoint@users.noreply.github.com>
Date: Sat, 3 Aug 2024 00:31:32 -0400
Subject: [PATCH 5/8] Update src/base/EIP712.sol

Co-authored-by: Sara Reynolds <30504811+snreynolds@users.noreply.github.com>
---
 src/base/EIP712.sol | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/base/EIP712.sol b/src/base/EIP712.sol
index a4074350..6cf8d171 100644
--- a/src/base/EIP712.sol
+++ b/src/base/EIP712.sol
@@ -25,7 +25,7 @@ contract EIP712 is IEIP712 {
     }
 
     /// @notice Returns the domain separator for the current chain.
-    /// @dev Uses cached version if chainid and address are unchanged from construction.
+    /// @dev Uses cached version if chainid is unchanged from construction.
     function DOMAIN_SEPARATOR() public view override returns (bytes32) {
         return block.chainid == _CACHED_CHAIN_ID ? _CACHED_DOMAIN_SEPARATOR : _buildDomainSeparator();
     }

From e553340e69597e497d3f999ab8d3a271761cf567 Mon Sep 17 00:00:00 2001
From: saucepoint <saucepoint@protonmail.com>
Date: Sat, 3 Aug 2024 00:48:25 -0400
Subject: [PATCH 6/8] natspec for delegatecall error

---
 src/base/EIP712.sol | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/base/EIP712.sol b/src/base/EIP712.sol
index 6cf8d171..6c0148ab 100644
--- a/src/base/EIP712.sol
+++ b/src/base/EIP712.sol
@@ -5,6 +5,7 @@ import {IEIP712} from "../interfaces/IEIP712.sol";
 
 /// @notice Generic EIP712 implementation
 /// @dev Maintains cross-chain replay protection in the event of a fork
+/// @dev Should not be delegatecall'd because DOMAIN_SEPARATOR returns the cached hash and does not recompute with the delegatecallers address
 /// @dev Reference: https://github.com/Uniswap/permit2/blob/main/src/EIP712.sol
 /// @dev Reference: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/cryptography/EIP712.sol
 contract EIP712 is IEIP712 {

From 4a74d8d5e46ae85d795cc23e5fbd5cdeeb55c6a3 Mon Sep 17 00:00:00 2001
From: saucepoint <saucepoint@protonmail.com>
Date: Sat, 3 Aug 2024 22:15:36 -0400
Subject: [PATCH 7/8] assembly optimization, pr nits

---
 .forge-snapshots/PositionManager_permit.snap     |  2 +-
 .../PositionManager_permit_secondPosition.snap   |  2 +-
 .../PositionManager_permit_twice.snap            |  2 +-
 src/base/EIP712.sol                              | 16 ++++++++++++----
 4 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/.forge-snapshots/PositionManager_permit.snap b/.forge-snapshots/PositionManager_permit.snap
index c3bc0823..8ebdf959 100644
--- a/.forge-snapshots/PositionManager_permit.snap
+++ b/.forge-snapshots/PositionManager_permit.snap
@@ -1 +1 @@
-79636
\ No newline at end of file
+79566
\ No newline at end of file
diff --git a/.forge-snapshots/PositionManager_permit_secondPosition.snap b/.forge-snapshots/PositionManager_permit_secondPosition.snap
index fa2386f9..972b19ad 100644
--- a/.forge-snapshots/PositionManager_permit_secondPosition.snap
+++ b/.forge-snapshots/PositionManager_permit_secondPosition.snap
@@ -1 +1 @@
-62524
\ No newline at end of file
+62454
\ No newline at end of file
diff --git a/.forge-snapshots/PositionManager_permit_twice.snap b/.forge-snapshots/PositionManager_permit_twice.snap
index 7cfd8d74..a3347104 100644
--- a/.forge-snapshots/PositionManager_permit_twice.snap
+++ b/.forge-snapshots/PositionManager_permit_twice.snap
@@ -1 +1 @@
-45412
\ No newline at end of file
+45342
\ No newline at end of file
diff --git a/src/base/EIP712.sol b/src/base/EIP712.sol
index 6c0148ab..5b4ea0f5 100644
--- a/src/base/EIP712.sol
+++ b/src/base/EIP712.sol
@@ -15,8 +15,8 @@ contract EIP712 is IEIP712 {
     uint256 private immutable _CACHED_CHAIN_ID;
     bytes32 private immutable _HASHED_NAME;
 
-    bytes32 private constant _TYPE_HASH =
-        keccak256("EIP712Domain(string name,uint256 chainId,address verifyingContract)");
+    /// @dev equal to keccak256("EIP712Domain(string name,uint256 chainId,address verifyingContract)")
+    bytes32 private constant _TYPE_HASH = 0x8cad95687ba82c2ce50e74f7b754645e5117c3a5bec8151c0726d5857980a866;
 
     constructor(string memory name) {
         _HASHED_NAME = keccak256(bytes(name));
@@ -37,7 +37,15 @@ contract EIP712 is IEIP712 {
     }
 
     /// @notice Creates an EIP-712 typed data hash
-    function _hashTypedData(bytes32 dataHash) internal view returns (bytes32) {
-        return keccak256(abi.encodePacked("\x19\x01", DOMAIN_SEPARATOR(), dataHash));
+    function _hashTypedData(bytes32 dataHash) internal view returns (bytes32 digest) {
+        // equal to keccak256(abi.encodePacked("\x19\x01", DOMAIN_SEPARATOR(), dataHash));
+        bytes32 domainSeparator = DOMAIN_SEPARATOR();
+        assembly ("memory-safe") {
+            let fmp := mload(0x40)
+            mstore(fmp, hex"1901")
+            mstore(add(fmp, 0x02), domainSeparator)
+            mstore(add(fmp, 0x22), dataHash)
+            digest := keccak256(fmp, 0x42)
+        }
     }
 }

From 0826c12c23f69c19b234f7247df565e124e449c1 Mon Sep 17 00:00:00 2001
From: saucepoint <saucepoint@protonmail.com>
Date: Sat, 3 Aug 2024 22:15:52 -0400
Subject: [PATCH 8/8] test to validate assembly

---
 test/EIP712.t.sol | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 test/EIP712.t.sol

diff --git a/test/EIP712.t.sol b/test/EIP712.t.sol
new file mode 100644
index 00000000..badf6c9c
--- /dev/null
+++ b/test/EIP712.t.sol
@@ -0,0 +1,47 @@
+//SPDX-License-Identifier: MIT
+pragma solidity ^0.8.24;
+
+import "forge-std/Test.sol";
+
+import {EIP712} from "../src/base/EIP712.sol";
+
+contract EIP712Test is EIP712, Test {
+    constructor() EIP712("EIP712Test") {}
+
+    function setUp() public {}
+
+    function test_domainSeparator() public view {
+        assertEq(
+            DOMAIN_SEPARATOR(),
+            keccak256(
+                abi.encode(
+                    keccak256("EIP712Domain(string name,uint256 chainId,address verifyingContract)"),
+                    keccak256(bytes("EIP712Test")),
+                    block.chainid,
+                    address(this)
+                )
+            )
+        );
+    }
+
+    function test_hashTypedData() public view {
+        bytes32 dataHash = keccak256(abi.encodePacked("data"));
+        assertEq(_hashTypedData(dataHash), keccak256(abi.encodePacked("\x19\x01", DOMAIN_SEPARATOR(), dataHash)));
+    }
+
+    function test_rebuildDomainSeparator() public {
+        uint256 chainId = 4444;
+        vm.chainId(chainId);
+        assertEq(
+            DOMAIN_SEPARATOR(),
+            keccak256(
+                abi.encode(
+                    keccak256("EIP712Domain(string name,uint256 chainId,address verifyingContract)"),
+                    keccak256(bytes("EIP712Test")),
+                    chainId,
+                    address(this)
+                )
+            )
+        );
+    }
+}