Split StorageSlot into TransientSlot (#5239)

Co-authored-by: Hadrien Croubois <hadrien.croubois@gmail.com>
Signed-off-by: Hadrien Croubois <hadrien.croubois@gmail.com>

contracts/mocks/StorageSlotMock.sol

@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 // This file was procedurally generated from scripts/generate/templates/StorageSlotMock.js.
 
-pragma solidity ^0.8.24;
+pragma solidity ^0.8.20;
 
 import {Multicall} from "../utils/Multicall.sol";
 import {StorageSlot} from "../utils/StorageSlot.sol";
@@ -84,54 +84,4 @@ contract StorageSlotMock is Multicall {
     function getBytesStorage(uint256 key) public view returns (bytes memory) {
         return bytesMap[key].getBytesSlot().value;
     }
-
-    event AddressValue(bytes32 slot, address value);
-
-    function tloadAddress(bytes32 slot) public {
-        emit AddressValue(slot, slot.asAddress().tload());
-    }
-
-    function tstore(bytes32 slot, address value) public {
-        slot.asAddress().tstore(value);
-    }
-
-    event BooleanValue(bytes32 slot, bool value);
-
-    function tloadBoolean(bytes32 slot) public {
-        emit BooleanValue(slot, slot.asBoolean().tload());
-    }
-
-    function tstore(bytes32 slot, bool value) public {
-        slot.asBoolean().tstore(value);
-    }
-
-    event Bytes32Value(bytes32 slot, bytes32 value);
-
-    function tloadBytes32(bytes32 slot) public {
-        emit Bytes32Value(slot, slot.asBytes32().tload());
-    }
-
-    function tstore(bytes32 slot, bytes32 value) public {
-        slot.asBytes32().tstore(value);
-    }
-
-    event Uint256Value(bytes32 slot, uint256 value);
-
-    function tloadUint256(bytes32 slot) public {
-        emit Uint256Value(slot, slot.asUint256().tload());
-    }
-
-    function tstore(bytes32 slot, uint256 value) public {
-        slot.asUint256().tstore(value);
-    }
-
-    event Int256Value(bytes32 slot, int256 value);
-
-    function tloadInt256(bytes32 slot) public {
-        emit Int256Value(slot, slot.asInt256().tload());
-    }
-
-    function tstore(bytes32 slot, int256 value) public {
-        slot.asInt256().tstore(value);
-    }
 }

contracts/mocks/TransientSlotMock.sol

@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: MIT
+// This file was procedurally generated from scripts/generate/templates/TransientSlotMock.js.
+
+pragma solidity ^0.8.24;
+
+import {Multicall} from "../utils/Multicall.sol";
+import {TransientSlot} from "../utils/TransientSlot.sol";
+
+contract TransientSlotMock is Multicall {
+    using TransientSlot for *;
+
+    event AddressValue(bytes32 slot, address value);
+
+    function tloadAddress(bytes32 slot) public {
+        emit AddressValue(slot, slot.asAddress().tload());
+    }
+
+    function tstore(bytes32 slot, address value) public {
+        slot.asAddress().tstore(value);
+    }
+
+    event BooleanValue(bytes32 slot, bool value);
+
+    function tloadBoolean(bytes32 slot) public {
+        emit BooleanValue(slot, slot.asBoolean().tload());
+    }
+
+    function tstore(bytes32 slot, bool value) public {
+        slot.asBoolean().tstore(value);
+    }
+
+    event Bytes32Value(bytes32 slot, bytes32 value);
+
+    function tloadBytes32(bytes32 slot) public {
+        emit Bytes32Value(slot, slot.asBytes32().tload());
+    }
+
+    function tstore(bytes32 slot, bytes32 value) public {
+        slot.asBytes32().tstore(value);
+    }
+
+    event Uint256Value(bytes32 slot, uint256 value);
+
+    function tloadUint256(bytes32 slot) public {
+        emit Uint256Value(slot, slot.asUint256().tload());
+    }
+
+    function tstore(bytes32 slot, uint256 value) public {
+        slot.asUint256().tstore(value);
+    }
+
+    event Int256Value(bytes32 slot, int256 value);
+
+    function tloadInt256(bytes32 slot) public {
+        emit Int256Value(slot, slot.asInt256().tload());
+    }
+
+    function tstore(bytes32 slot, int256 value) public {
+        slot.asInt256().tstore(value);
+    }
+}

contracts/token/ERC20/extensions/draft-ERC20TemporaryApproval.sol

@@ -7,7 +7,7 @@ import {IERC20, ERC20} from "../ERC20.sol";
 import {IERC7674} from "../../../interfaces/draft-IERC7674.sol";
 import {Math} from "../../../utils/math/Math.sol";
 import {SlotDerivation} from "../../../utils/SlotDerivation.sol";
-import {StorageSlot} from "../../../utils/StorageSlot.sol";
+import {TransientSlot} from "../../../utils/TransientSlot.sol";
 
 /**
  * @dev Extension of {ERC20} that adds support for temporary allowances following ERC-7674.
@@ -18,8 +18,8 @@ import {StorageSlot} from "../../../utils/StorageSlot.sol";
  */
 abstract contract ERC20TemporaryApproval is ERC20, IERC7674 {
     using SlotDerivation for bytes32;
-    using StorageSlot for bytes32;
+    using TransientSlot for bytes32;
-    using StorageSlot for StorageSlot.Uint256SlotType;
+    using TransientSlot for TransientSlot.Uint256Slot;
 
     // keccak256(abi.encode(uint256(keccak256("openzeppelin.storage.ERC20_TEMPORARY_APPROVAL_STORAGE")) - 1)) & ~bytes32(uint256(0xff))
     bytes32 private constant ERC20_TEMPORARY_APPROVAL_STORAGE =
@@ -113,10 +113,7 @@ abstract contract ERC20TemporaryApproval is ERC20, IERC7674 {
         }
     }
 
-    function _temporaryAllowanceSlot(
+    function _temporaryAllowanceSlot(address owner, address spender) private pure returns (TransientSlot.Uint256Slot) {
-        address owner,
-        address spender
-    ) private pure returns (StorageSlot.Uint256SlotType) {
         return ERC20_TEMPORARY_APPROVAL_STORAGE.deriveMapping(owner).deriveMapping(spender).asUint256();
     }
 }

contracts/utils/README.adoc

@@ -34,7 +34,8 @@ Miscellaneous contracts and libraries containing utility functions you can use t
  * {Strings}: Common operations for strings formatting.
  * {ShortString}: Library to encode (and decode) short strings into (or from) a single bytes32 slot for optimizing costs. Short strings are limited to 31 characters.
  * {SlotDerivation}: Methods for deriving storage slot from ERC-7201 namespaces as well as from constructions such as mapping and arrays.
- * {StorageSlot}: Methods for accessing specific storage slots formatted as common primitive types. Also include primitives for reading from and writing to transient storage (only value types are currently supported).
+ * {StorageSlot}: Methods for accessing specific storage slots formatted as common primitive types. 
+ * {TransientSlot}: Primitives for reading from and writing to transient storage (only value types are currently supported).
  * {Multicall}: Abstract contract with a utility to allow batching together multiple calls in a single transaction. Useful for allowing EOAs to perform multiple operations at once.
  * {Context}: A utility for abstracting the sender and calldata in the current execution context.
  * {Packing}: A library for packing and unpacking multiple values into bytes32
@@ -130,6 +131,8 @@ Ethereum contracts have no native concept of an interface, so applications must
 
 {{StorageSlot}}
 
+{{TransientSlot}}
+
 {{Multicall}}
 
 {{Context}}

contracts/utils/ReentrancyGuardTransient.sol

@@ -3,7 +3,7 @@
 
 pragma solidity ^0.8.24;
 
-import {StorageSlot} from "./StorageSlot.sol";
+import {TransientSlot} from "./TransientSlot.sol";
 
 /**
  * @dev Variant of {ReentrancyGuard} that uses transient storage.
@@ -13,7 +13,7 @@ import {StorageSlot} from "./StorageSlot.sol";
  * _Available since v5.1._
  */
 abstract contract ReentrancyGuardTransient {
-    using StorageSlot for *;
+    using TransientSlot for *;
 
     // keccak256(abi.encode(uint256(keccak256("openzeppelin.storage.ReentrancyGuard")) - 1)) & ~bytes32(uint256(0xff))
     bytes32 private constant REENTRANCY_GUARD_STORAGE =

contracts/utils/StorageSlot.sol

@@ -2,7 +2,7 @@
 // OpenZeppelin Contracts (last updated v5.1.0-rc.0) (utils/StorageSlot.sol)
 // This file was procedurally generated from scripts/generate/templates/StorageSlot.js.
 
-pragma solidity ^0.8.24;
+pragma solidity ^0.8.20;
 
 /**
  * @dev Library for reading and writing primitive types to specific storage slots.
@@ -29,24 +29,6 @@ pragma solidity ^0.8.24;
  * }
  * ```
  *
- * Since version 5.1, this library also support writing and reading value types to and from transient storage.
- *
- *  * Example using transient storage:
- * ```solidity
- * contract Lock {
- *     // Define the slot. Alternatively, use the SlotDerivation library to derive the slot.
- *     bytes32 internal constant _LOCK_SLOT = 0xf4678858b2b588224636b8522b729e7722d32fc491da849ed75b3fdf3c84f542;
- *
- *     modifier locked() {
- *         require(!_LOCK_SLOT.asBoolean().tload());
- *
- *         _LOCK_SLOT.asBoolean().tstore(true);
- *         _;
- *         _LOCK_SLOT.asBoolean().tstore(false);
- *     }
- * }
- * ```
- *
  * TIP: Consider using this library along with {SlotDerivation}.
  */
 library StorageSlot {
@@ -158,154 +140,4 @@ library StorageSlot {
             r.slot := store.slot
         }
     }
-
-    /**
-     * @dev UDVT that represent a slot holding a address.
-     */
-    type AddressSlotType is bytes32;
-
-    /**
-     * @dev Cast an arbitrary slot to a AddressSlotType.
-     */
-    function asAddress(bytes32 slot) internal pure returns (AddressSlotType) {
-        return AddressSlotType.wrap(slot);
-    }
-
-    /**
-     * @dev UDVT that represent a slot holding a bool.
-     */
-    type BooleanSlotType is bytes32;
-
-    /**
-     * @dev Cast an arbitrary slot to a BooleanSlotType.
-     */
-    function asBoolean(bytes32 slot) internal pure returns (BooleanSlotType) {
-        return BooleanSlotType.wrap(slot);
-    }
-
-    /**
-     * @dev UDVT that represent a slot holding a bytes32.
-     */
-    type Bytes32SlotType is bytes32;
-
-    /**
-     * @dev Cast an arbitrary slot to a Bytes32SlotType.
-     */
-    function asBytes32(bytes32 slot) internal pure returns (Bytes32SlotType) {
-        return Bytes32SlotType.wrap(slot);
-    }
-
-    /**
-     * @dev UDVT that represent a slot holding a uint256.
-     */
-    type Uint256SlotType is bytes32;
-
-    /**
-     * @dev Cast an arbitrary slot to a Uint256SlotType.
-     */
-    function asUint256(bytes32 slot) internal pure returns (Uint256SlotType) {
-        return Uint256SlotType.wrap(slot);
-    }
-
-    /**
-     * @dev UDVT that represent a slot holding a int256.
-     */
-    type Int256SlotType is bytes32;
-
-    /**
-     * @dev Cast an arbitrary slot to a Int256SlotType.
-     */
-    function asInt256(bytes32 slot) internal pure returns (Int256SlotType) {
-        return Int256SlotType.wrap(slot);
-    }
-
-    /**
-     * @dev Load the value held at location `slot` in transient storage.
-     */
-    function tload(AddressSlotType slot) internal view returns (address value) {
-        assembly ("memory-safe") {
-            value := tload(slot)
-        }
-    }
-
-    /**
-     * @dev Store `value` at location `slot` in transient storage.
-     */
-    function tstore(AddressSlotType slot, address value) internal {
-        assembly ("memory-safe") {
-            tstore(slot, value)
-        }
-    }
-
-    /**
-     * @dev Load the value held at location `slot` in transient storage.
-     */
-    function tload(BooleanSlotType slot) internal view returns (bool value) {
-        assembly ("memory-safe") {
-            value := tload(slot)
-        }
-    }
-
-    /**
-     * @dev Store `value` at location `slot` in transient storage.
-     */
-    function tstore(BooleanSlotType slot, bool value) internal {
-        assembly ("memory-safe") {
-            tstore(slot, value)
-        }
-    }
-
-    /**
-     * @dev Load the value held at location `slot` in transient storage.
-     */
-    function tload(Bytes32SlotType slot) internal view returns (bytes32 value) {
-        assembly ("memory-safe") {
-            value := tload(slot)
-        }
-    }
-
-    /**
-     * @dev Store `value` at location `slot` in transient storage.
-     */
-    function tstore(Bytes32SlotType slot, bytes32 value) internal {
-        assembly ("memory-safe") {
-            tstore(slot, value)
-        }
-    }
-
-    /**
-     * @dev Load the value held at location `slot` in transient storage.
-     */
-    function tload(Uint256SlotType slot) internal view returns (uint256 value) {
-        assembly ("memory-safe") {
-            value := tload(slot)
-        }
-    }
-
-    /**
-     * @dev Store `value` at location `slot` in transient storage.
-     */
-    function tstore(Uint256SlotType slot, uint256 value) internal {
-        assembly ("memory-safe") {
-            tstore(slot, value)
-        }
-    }
-
-    /**
-     * @dev Load the value held at location `slot` in transient storage.
-     */
-    function tload(Int256SlotType slot) internal view returns (int256 value) {
-        assembly ("memory-safe") {
-            value := tload(slot)
-        }
-    }
-
-    /**
-     * @dev Store `value` at location `slot` in transient storage.
-     */
-    function tstore(Int256SlotType slot, int256 value) internal {
-        assembly ("memory-safe") {
-            tstore(slot, value)
-        }
-    }
 }

contracts/utils/TransientSlot.sol

@@ -0,0 +1,182 @@
+// SPDX-License-Identifier: MIT
+// This file was procedurally generated from scripts/generate/templates/TransientSlot.js.
+
+pragma solidity ^0.8.24;
+
+/**
+ * @dev Library for reading and writing value-types to specific transient storage slots.
+ *
+ * Transient slots are often used to store temporary values that are removed after the current transaction.
+ * This library helps with reading and writing to such slots without the need for inline assembly.
+ *
+ *  * Example reading and writing values using transient storage:
+ * ```solidity
+ * contract Lock {
+ *     using TransientSlot for *;
+ *
+ *     // Define the slot. Alternatively, use the SlotDerivation library to derive the slot.
+ *     bytes32 internal constant _LOCK_SLOT = 0xf4678858b2b588224636b8522b729e7722d32fc491da849ed75b3fdf3c84f542;
+ *
+ *     modifier locked() {
+ *         require(!_LOCK_SLOT.asBoolean().tload());
+ *
+ *         _LOCK_SLOT.asBoolean().tstore(true);
+ *         _;
+ *         _LOCK_SLOT.asBoolean().tstore(false);
+ *     }
+ * }
+ * ```
+ *
+ * TIP: Consider using this library along with {SlotDerivation}.
+ */
+library TransientSlot {
+    /**
+     * @dev UDVT that represent a slot holding a address.
+     */
+    type AddressSlot is bytes32;
+
+    /**
+     * @dev Cast an arbitrary slot to a AddressSlot.
+     */
+    function asAddress(bytes32 slot) internal pure returns (AddressSlot) {
+        return AddressSlot.wrap(slot);
+    }
+
+    /**
+     * @dev UDVT that represent a slot holding a bool.
+     */
+    type BooleanSlot is bytes32;
+
+    /**
+     * @dev Cast an arbitrary slot to a BooleanSlot.
+     */
+    function asBoolean(bytes32 slot) internal pure returns (BooleanSlot) {
+        return BooleanSlot.wrap(slot);
+    }
+
+    /**
+     * @dev UDVT that represent a slot holding a bytes32.
+     */
+    type Bytes32Slot is bytes32;
+
+    /**
+     * @dev Cast an arbitrary slot to a Bytes32Slot.
+     */
+    function asBytes32(bytes32 slot) internal pure returns (Bytes32Slot) {
+        return Bytes32Slot.wrap(slot);
+    }
+
+    /**
+     * @dev UDVT that represent a slot holding a uint256.
+     */
+    type Uint256Slot is bytes32;
+
+    /**
+     * @dev Cast an arbitrary slot to a Uint256Slot.
+     */
+    function asUint256(bytes32 slot) internal pure returns (Uint256Slot) {
+        return Uint256Slot.wrap(slot);
+    }
+
+    /**
+     * @dev UDVT that represent a slot holding a int256.
+     */
+    type Int256Slot is bytes32;
+
+    /**
+     * @dev Cast an arbitrary slot to a Int256Slot.
+     */
+    function asInt256(bytes32 slot) internal pure returns (Int256Slot) {
+        return Int256Slot.wrap(slot);
+    }
+
+    /**
+     * @dev Load the value held at location `slot` in transient storage.
+     */
+    function tload(AddressSlot slot) internal view returns (address value) {
+        assembly ("memory-safe") {
+            value := tload(slot)
+        }
+    }
+
+    /**
+     * @dev Store `value` at location `slot` in transient storage.
+     */
+    function tstore(AddressSlot slot, address value) internal {
+        assembly ("memory-safe") {
+            tstore(slot, value)
+        }
+    }
+
+    /**
+     * @dev Load the value held at location `slot` in transient storage.
+     */
+    function tload(BooleanSlot slot) internal view returns (bool value) {
+        assembly ("memory-safe") {
+            value := tload(slot)
+        }
+    }
+
+    /**
+     * @dev Store `value` at location `slot` in transient storage.
+     */
+    function tstore(BooleanSlot slot, bool value) internal {
+        assembly ("memory-safe") {
+            tstore(slot, value)
+        }
+    }
+
+    /**
+     * @dev Load the value held at location `slot` in transient storage.
+     */
+    function tload(Bytes32Slot slot) internal view returns (bytes32 value) {
+        assembly ("memory-safe") {
+            value := tload(slot)
+        }
+    }
+
+    /**
+     * @dev Store `value` at location `slot` in transient storage.
+     */
+    function tstore(Bytes32Slot slot, bytes32 value) internal {
+        assembly ("memory-safe") {
+            tstore(slot, value)
+        }
+    }
+
+    /**
+     * @dev Load the value held at location `slot` in transient storage.
+     */
+    function tload(Uint256Slot slot) internal view returns (uint256 value) {
+        assembly ("memory-safe") {
+            value := tload(slot)
+        }
+    }
+
+    /**
+     * @dev Store `value` at location `slot` in transient storage.
+     */
+    function tstore(Uint256Slot slot, uint256 value) internal {
+        assembly ("memory-safe") {
+            tstore(slot, value)
+        }
+    }
+
+    /**
+     * @dev Load the value held at location `slot` in transient storage.
+     */
+    function tload(Int256Slot slot) internal view returns (int256 value) {
+        assembly ("memory-safe") {
+            value := tload(slot)
+        }
+    }
+
+    /**
+     * @dev Store `value` at location `slot` in transient storage.
+     */
+    function tstore(Int256Slot slot, int256 value) internal {
+        assembly ("memory-safe") {
+            tstore(slot, value)
+        }
+    }
+}

docs/modules/ROOT/pages/utilities.adoc

@@ -319,7 +319,7 @@ function _setImplementation(address newImplementation) internal {
 }
 ----
 
-The xref:api:utils.adoc#StorageSlot[`StorageSlot`] library also supports transient storage through user defined value types (https://docs.soliditylang.org/en/latest/types.html#user-defined-value-types[UDVTs]), which enables the same value types as in Solidity.
+The xref:api:utils.adoc#TransientSlot[`TransientSlot`] library supports transient storage through user defined value types (https://docs.soliditylang.org/en/latest/types.html#user-defined-value-types[UDVTs]), which enables the same value types as in Solidity.
 
 [source,solidity]
 ----

scripts/generate/run.js

@@ -39,9 +39,11 @@ for (const [file, template] of Object.entries({
   'utils/structs/EnumerableMap.sol': './templates/EnumerableMap.js',
   'utils/SlotDerivation.sol': './templates/SlotDerivation.js',
   'utils/StorageSlot.sol': './templates/StorageSlot.js',
+  'utils/TransientSlot.sol': './templates/TransientSlot.js',
   'utils/Arrays.sol': './templates/Arrays.js',
   'utils/Packing.sol': './templates/Packing.js',
   'mocks/StorageSlotMock.sol': './templates/StorageSlotMock.js',
+  'mocks/TransientSlotMock.sol': './templates/TransientSlotMock.js',
 })) {
   generateFromTemplate(file, template, './contracts/');
 }

scripts/generate/templates/StorageSlot.js

@@ -2,7 +2,7 @@ const format = require('../format-lines');
 const { TYPES } = require('./Slot.opts');
 
 const header = `\
-pragma solidity ^0.8.24;
+pragma solidity ^0.8.20;
 
 /**
  * @dev Library for reading and writing primitive types to specific storage slots.
@@ -29,24 +29,6 @@ pragma solidity ^0.8.24;
  * }
  * \`\`\`
  *
- * Since version 5.1, this library also support writing and reading value types to and from transient storage.
- *
- *  * Example using transient storage:
- * \`\`\`solidity
- * contract Lock {
- *     // Define the slot. Alternatively, use the SlotDerivation library to derive the slot.
- *     bytes32 internal constant _LOCK_SLOT = 0xf4678858b2b588224636b8522b729e7722d32fc491da849ed75b3fdf3c84f542;
- *
- *     modifier locked() {
- *         require(!_LOCK_SLOT.asBoolean().tload());
- *
- *         _LOCK_SLOT.asBoolean().tstore(true);
- *         _;
- *         _LOCK_SLOT.asBoolean().tstore(false);
- *     }
- * }
- * \`\`\`
- *
  * TIP: Consider using this library along with {SlotDerivation}.
  */
 `;
@@ -81,40 +63,6 @@ function get${name}Slot(${type} storage store) internal pure returns (${name}Slo
 }
 `;
 
-const udvt = ({ type, name }) => `\
-/**
- * @dev UDVT that represent a slot holding a ${type}.
- */
-type ${name}SlotType is bytes32;
-
-/**
- * @dev Cast an arbitrary slot to a ${name}SlotType.
- */
-function as${name}(bytes32 slot) internal pure returns (${name}SlotType) {
-    return ${name}SlotType.wrap(slot);
-}
-`;
-
-const transient = ({ type, name }) => `\
-/**
- * @dev Load the value held at location \`slot\` in transient storage.
- */
-function tload(${name}SlotType slot) internal view returns (${type} value) {
-    assembly ("memory-safe") {
-        value := tload(slot)
-    }
-}
-
-/**
- * @dev Store \`value\` at location \`slot\` in transient storage.
- */
-function tstore(${name}SlotType slot, ${type} value) internal {
-    assembly ("memory-safe") {
-        tstore(slot, value)
-    }
-}
-`;
-
 // GENERATE
 module.exports = format(
   header.trimEnd(),
@@ -123,8 +71,6 @@ module.exports = format(
     [].concat(
       TYPES.map(type => struct(type)),
       TYPES.flatMap(type => [get(type), !type.isValueType && getStorage(type)].filter(Boolean)),
-      TYPES.filter(type => type.isValueType).map(type => udvt(type)),
-      TYPES.filter(type => type.isValueType).map(type => transient(type)),
     ),
   ).trimEnd(),
   '}',

scripts/generate/templates/StorageSlotMock.js

@@ -2,7 +2,7 @@ const format = require('../format-lines');
 const { TYPES } = require('./Slot.opts');
 
 const header = `\
-pragma solidity ^0.8.24;
+pragma solidity ^0.8.20;
 
 import {Multicall} from "../utils/Multicall.sol";
 import {StorageSlot} from "../utils/StorageSlot.sol";
@@ -40,18 +40,6 @@ function get${name}Storage(uint256 key) public view returns (${type} memory) {
 }
 `;
 
-const transient = ({ type, name }) => `\
-event ${name}Value(bytes32 slot, ${type} value);
-
-function tload${name}(bytes32 slot) public {
-    emit ${name}Value(slot, slot.as${name}().tload());
-}
-
-function tstore(bytes32 slot, ${type} value) public {
-    slot.as${name}().tstore(value);
-}
-`;
-
 // GENERATE
 module.exports = format(
   header,
@@ -63,7 +51,6 @@ module.exports = format(
       TYPES.filter(type => type.isValueType).map(type => storageSetValueType(type)),
       TYPES.filter(type => type.isValueType).map(type => storageGetValueType(type)),
       TYPES.filter(type => !type.isValueType).map(type => storageSetNonValueType(type)),
-      TYPES.filter(type => type.isValueType).map(type => transient(type)),
     ),
   ).trimEnd(),
   '}',

scripts/generate/templates/TransientSlot.js

@@ -0,0 +1,80 @@
+const format = require('../format-lines');
+const { TYPES } = require('./Slot.opts');
+
+const header = `\
+pragma solidity ^0.8.24;
+
+/**
+ * @dev Library for reading and writing value-types to specific transient storage slots.
+ *
+ * Transient slots are often used to store temporary values that are removed after the current transaction.
+ * This library helps with reading and writing to such slots without the need for inline assembly.
+ *
+ *  * Example reading and writing values using transient storage:
+ * \`\`\`solidity
+ * contract Lock {
+ *     using TransientSlot for *;
+ *
+ *     // Define the slot. Alternatively, use the SlotDerivation library to derive the slot.
+ *     bytes32 internal constant _LOCK_SLOT = 0xf4678858b2b588224636b8522b729e7722d32fc491da849ed75b3fdf3c84f542;
+ *
+ *     modifier locked() {
+ *         require(!_LOCK_SLOT.asBoolean().tload());
+ *
+ *         _LOCK_SLOT.asBoolean().tstore(true);
+ *         _;
+ *         _LOCK_SLOT.asBoolean().tstore(false);
+ *     }
+ * }
+ * \`\`\`
+ *
+ * TIP: Consider using this library along with {SlotDerivation}.
+ */
+`;
+
+const udvt = ({ type, name }) => `\
+/**
+ * @dev UDVT that represent a slot holding a ${type}.
+ */
+type ${name}Slot is bytes32;
+
+/**
+ * @dev Cast an arbitrary slot to a ${name}Slot.
+ */
+function as${name}(bytes32 slot) internal pure returns (${name}Slot) {
+    return ${name}Slot.wrap(slot);
+}
+`;
+
+const transient = ({ type, name }) => `\
+/**
+ * @dev Load the value held at location \`slot\` in transient storage.
+ */
+function tload(${name}Slot slot) internal view returns (${type} value) {
+    assembly ("memory-safe") {
+        value := tload(slot)
+    }
+}
+
+/**
+ * @dev Store \`value\` at location \`slot\` in transient storage.
+ */
+function tstore(${name}Slot slot, ${type} value) internal {
+    assembly ("memory-safe") {
+        tstore(slot, value)
+    }
+}
+`;
+
+// GENERATE
+module.exports = format(
+  header.trimEnd(),
+  'library TransientSlot {',
+  format(
+    [].concat(
+      TYPES.filter(type => type.isValueType).map(type => udvt(type)),
+      TYPES.filter(type => type.isValueType).map(type => transient(type)),
+    ),
+  ).trimEnd(),
+  '}',
+);

scripts/generate/templates/TransientSlotMock.js

@@ -0,0 +1,35 @@
+const format = require('../format-lines');
+const { TYPES } = require('./Slot.opts');
+
+const header = `\
+pragma solidity ^0.8.24;
+
+import {Multicall} from "../utils/Multicall.sol";
+import {TransientSlot} from "../utils/TransientSlot.sol";
+`;
+
+const transient = ({ type, name }) => `\
+event ${name}Value(bytes32 slot, ${type} value);
+
+function tload${name}(bytes32 slot) public {
+    emit ${name}Value(slot, slot.as${name}().tload());
+}
+
+function tstore(bytes32 slot, ${type} value) public {
+    slot.as${name}().tstore(value);
+}
+`;
+
+// GENERATE
+module.exports = format(
+  header,
+  'contract TransientSlotMock is Multicall {',
+  format(
+    [].concat(
+      'using TransientSlot for *;',
+      '',
+      TYPES.filter(type => type.isValueType).map(type => transient(type)),
+    ),
+  ).trimEnd(),
+  '}',
+);

test/utils/StorageSlot.test.js

@@ -70,37 +70,4 @@ describe('StorageSlot', function () {
       });
     });
   }
-
-  for (const { name, type, value, zero } of TYPES.filter(type => type.isValueType)) {
-    describe(`${type} transient slot`, function () {
-      const load = `tload${name}(bytes32)`;
-      const store = `tstore(bytes32,${type})`;
-      const event = `${name}Value`;
-
-      it('load', async function () {
-        await expect(this.mock[load](slot)).to.emit(this.mock, event).withArgs(slot, zero);
-      });
-
-      it('store and load (2 txs)', async function () {
-        await this.mock[store](slot, value);
-        await expect(this.mock[load](slot)).to.emit(this.mock, event).withArgs(slot, zero);
-      });
-
-      it('store and load (batched)', async function () {
-        await expect(
-          this.mock.multicall([
-            this.mock.interface.encodeFunctionData(store, [slot, value]),
-            this.mock.interface.encodeFunctionData(load, [slot]),
-            this.mock.interface.encodeFunctionData(load, [otherSlot]),
-          ]),
-        )
-          .to.emit(this.mock, event)
-          .withArgs(slot, value)
-          .to.emit(this.mock, event)
-          .withArgs(otherSlot, zero);
-
-        await expect(this.mock[load](slot)).to.emit(this.mock, event).withArgs(slot, zero);
-      });
-    });
-  }
 });

test/utils/TransientSlot.test.js

@@ -0,0 +1,59 @@
+const { ethers } = require('hardhat');
+const { expect } = require('chai');
+const { loadFixture } = require('@nomicfoundation/hardhat-network-helpers');
+const { generators } = require('../helpers/random');
+
+const slot = ethers.id('some.storage.slot');
+const otherSlot = ethers.id('some.other.storage.slot');
+
+// Non-value types are not supported by the `TransientSlot` library.
+const TYPES = [
+  { name: 'Boolean', type: 'bool', value: true, zero: false },
+  { name: 'Address', type: 'address', value: generators.address(), zero: generators.address.zero },
+  { name: 'Bytes32', type: 'bytes32', value: generators.bytes32(), zero: generators.bytes32.zero },
+  { name: 'Uint256', type: 'uint256', value: generators.uint256(), zero: generators.uint256.zero },
+  { name: 'Int256', type: 'int256', value: generators.int256(), zero: generators.int256.zero },
+];
+
+async function fixture() {
+  return { mock: await ethers.deployContract('TransientSlotMock') };
+}
+
+describe('TransientSlot', function () {
+  beforeEach(async function () {
+    Object.assign(this, await loadFixture(fixture));
+  });
+
+  for (const { name, type, value, zero } of TYPES) {
+    describe(`${type} transient slot`, function () {
+      const load = `tload${name}(bytes32)`;
+      const store = `tstore(bytes32,${type})`;
+      const event = `${name}Value`;
+
+      it('load', async function () {
+        await expect(this.mock[load](slot)).to.emit(this.mock, event).withArgs(slot, zero);
+      });
+
+      it('store and load (2 txs)', async function () {
+        await this.mock[store](slot, value);
+        await expect(this.mock[load](slot)).to.emit(this.mock, event).withArgs(slot, zero);
+      });
+
+      it('store and load (batched)', async function () {
+        await expect(
+          this.mock.multicall([
+            this.mock.interface.encodeFunctionData(store, [slot, value]),
+            this.mock.interface.encodeFunctionData(load, [slot]),
+            this.mock.interface.encodeFunctionData(load, [otherSlot]),
+          ]),
+        )
+          .to.emit(this.mock, event)
+          .withArgs(slot, value)
+          .to.emit(this.mock, event)
+          .withArgs(otherSlot, zero);
+
+        await expect(this.mock[load](slot)).to.emit(this.mock, event).withArgs(slot, zero);
+      });
+    });
+  }
+});