daoio · daoio · Aug 25, 2025 · Aug 25, 2025 · Aug 25, 2025 · Aug 25, 2025
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
@@ -27,11 +27,6 @@ jobs:
         run: |
           forge --version
 
-      - name: Run Forge fmt
-        run: |
-          forge fmt --check
-        id: fmt
-
       - name: Run Forge build
         run: |
           forge build --sizes

diff --git a/README.md b/README.md
@@ -12,30 +12,28 @@ forge test
 ```
 
 ## Storage layout of `SemVerProxy`
-`SemVerProxy` reserves storage slots **0 to 99** for implementation contracts by declaring a fixed-size array that occupies these slots:
-```solidity
-uint256[100] private __gap; // Reserves slots 0-99 for implementations
-```
-So, the storage layout of a proxy and an arbitrary implementation contract can be represented as follows:
+`SemVerProxy` stores variables in the storage, starting at slot 1000. Therefore, implementation contracts can safely use all storage slots except 1000, 1001, and 1002.
+So, the storage layout of the proxy and an arbitrary implementation contract can be represented as follows:
 ```text
 Proxy storage layout:
-┌─────────────┐
-│ Slot 0-99   │ ← `__gap` placeholder (reserved for implementations)
-├─────────────┤
-│ Slot 100    │ ← `_latestVersion`
-│ Slot 101    │ ← Other state variables
-│ ...         │
-└─────────────┘
+┌───────────────┐
+│ Slot 0-1000   │ ← empty
+├───────────────┤
+│ Slot 1000     │ ← `_latestVersion`
+│ Slot 1001     │ ← `_releases` mapping
+│ Slot 1002     │ ← `_subscribedClients` mapping
+│ ...           │
+└───────────────┘
 
-Implementation storage example:
-┌─────────────┐
-│ Slot 0      │ ← Implementation's first state variable
-│ Slot 1      │ ← Implementation's second state variable
-│ ...         │
-│ Slot 99     │ ← Last available slot for implementation
-├─────────────┤
-| Slot 100    | ← ⚠️ This will collide with proxy's storage
-└─────────────┘
+Implementation's storage example:
+┌───────────────┐
+│ Slot 0        │ ← Implementation's 1st state variable
+│ Slot 1        │ ← Implementation's 2nd state variable
+│ ...           │
+│ Slot 999      │ ← Implementation's 998th state variable
+├───────────────┤
+| Slot 1000     │ ← ⚠️ This will collide with proxy's storage
+└───────────────┘
 ```
 
 ## Releases and Versioning
@@ -91,5 +89,5 @@ function unsubscribeFromVersioning() external;
 ```
 
 ## Security Considerations
-- Since `SemVerProxy` only reserves slots from 0 to 99, any 100+ slot of the implementation will collide with proxy.
+- Storing variables in implementation's storage at slots 1000, 1001, 1002 will collide with the proxy's storage.
 - `SemVerProxy` has externally accessable function, therefore there's a possibiliy of function selector clash (i.e., if implementation defines functions that have the same signature as external functions of `SemVerProxy`).
diff --git a/foundry.toml b/foundry.toml
@@ -7,4 +7,6 @@ libs = ["lib"]
 runs = 1000
 depth = 300
 
+solc_version = "0.8.30"
+
 # See more config options https://github.com/foundry-rs/foundry/blob/master/crates/config/README.md#all-options
diff --git a/src/SemVerProxy.sol b/src/SemVerProxy.sol
@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-pragma solidity ^0.8.28;
+pragma solidity 0.8.30;
 
 import {TransparentUpgradeableProxy, ERC1967Utils} from "openzeppelin-contracts/contracts/proxy/transparent/TransparentUpgradeableProxy.sol";
 import {Versioning, Version, EncodedVersion} from "./lib/Versioning.sol";
@@ -23,31 +23,22 @@ import {Clients, Client} from "./lib/Clients.sol";
  *      specified {_fallback} will delegate to the latest release.
  *
  * @dev Latest version is stored in a storage slot, specified in ERC-1967.
+ *
+ * @dev Storage variables are stored starting from 1000th slot.
  */
-contract SemVerProxy is TransparentUpgradeableProxy {
-    /**
-     * @dev Since {store} and {obtainRelease} are methods
-     *      that should be applied to {mapping(EncodedVersion => address)}
-     *      we limit them exactly to this mapping type.
-     */
+contract SemVerProxy is TransparentUpgradeableProxy layout at 1_000 {
     using {
         Versioning.store,
         Versioning.obtainRelease
     } for mapping(EncodedVersion => address);
-    /**
-     * @dev Incrementors and {encode} functions are limited
-     *      to be applied to {Version} struct.
-     */
+
     using {
         Versioning.incMajor,
         Versioning.incMinor,
         Versioning.incPatch,
         Versioning.encode
     } for Version;
-    /**
-     * @dev Subscription logic is limited to be
-     *      applied to {mapping(Client => address)} type.
-     */
+
     using {
         Clients.subscribe,
         Clients.unsubscribe,
@@ -60,16 +51,9 @@ contract SemVerProxy is TransparentUpgradeableProxy {
     event ClientUnsubscribed(Client indexed client);
 
     /***                   * STORAGE *                   ***/
-    /**
-     * @dev Reserve 100 storage slots to be used in implementations.
-     * @notice Any 99+ slot inside implementation will overwrite
-     *         storage of this proxy,
-     *         Therefore, implementations can only safely use
-     *         slots between 0 and 99.
-     */
-    uint256[100] private __gap;
 
     /// @notice Stores SemVer-like latest version of the implemenation.
+    /// @dev {_latestVersion} is stored in storage slot [1_000].
     Version internal _latestVersion;
 
     /// @notice Stores addresses of every existing version.

diff --git a/src/interfaces/ISemVerProxy.sol b/src/interfaces/ISemVerProxy.sol
@@ -4,17 +4,19 @@ pragma solidity ^0.8.28;
 import {Version, EncodedVersion} from "../lib/Versioning.sol";
 
 interface ISemVerProxy {
-    function latestVersion() external view returns(Version memory);
+    function latestVersion() external view returns (Version memory);
     function latestEncoded() external view returns (EncodedVersion);
     function latestRelease() external view returns (address);
-
-    /*~~~~~~~~~~~~~~~~~~~~~~ CLIENT ACTIONS ~~~~~~~~~~~~~~~~~~~~~~*/
 
+    /**
+     *                   * CLIENT ACTIONS *                   **
+     */
     function subscribeToVersion(Version memory version) external;
     function unsubscribeFromVersioning() external;
 
-    /*~~~~~~~~~~~~~~~~~~~~~~ ADMIN ACTIONS ~~~~~~~~~~~~~~~~~~~~~~*/
-
+    /**
+     *                   * ADMIN ACTIONS *                   **
+     */
     function releaseMajor(address release, bytes memory data) external;
     function releaseMinor(address release, bytes memory data) external;
     function releasePatch(address release, bytes memory data) external;

diff --git a/test/SemVerProxy.t.sol b/test/SemVerProxy.t.sol
@@ -1,4 +1,4 @@
-pragma solidity ^0.8.28;
+pragma solidity 0.8.30;
 
 import {ProxyAdmin} from "openzeppelin-contracts/contracts/proxy/transparent/TransparentUpgradeableProxy.sol";
 import {Versioning, Version, EncodedVersion} from "../src/lib/Versioning.sol";
@@ -49,7 +49,7 @@ contract SemVerProxyTest is Test {
 
     // Verify that writing to unsafe slots breaks storage.
     function test_implementationBreaksStorage() public {
-        // This contract might write to 100th storage slot.
+        // This contract might write to 1_000th storage slot.
         Breaking breaking = new Breaking();
 
         vm.prank(address(proxyAdmin));
@@ -60,27 +60,26 @@ contract SemVerProxyTest is Test {
         (uint64 major, uint64 minor, uint128 patch) = implementation
             .latestVersion_();
 
-	// This will succeed, since {Breaking} contract
-	// will read from a storage slot already occupied
-	// by the {SemVerProxy}.
+        // This will succeed, since {Breaking} contract
+        // will read from a storage slot already occupied
+        // by the {SemVerProxy}.
         _compareVersions(
             Version(major, minor, patch),
             semVerProxy.latestVersion()
         );
 
-	implementation.setVersion();
-	(major, minor, patch) = implementation
-            .latestVersion_();
+        implementation.setVersion();
+        (major, minor, patch) = implementation.latestVersion_();
 
-	// This will succeed again, because at this point
-	// the storage slot {100} has collided between
-	// {SemVerProxy} and {Breaking} contract, and
-	// {setVersion} call has ovrewritten {_latestVersion}
-	// storage variable of {SemVerProxy}.
+        // This will succeed again, because at this point
+        // the storage slot {1_000} has collided between
+        // {SemVerProxy} and {Breaking} contract, and
+        // {setVersion} call has ovrewritten {_latestVersion}
+        // storage variable of {SemVerProxy}.
         _compareVersions(
             Version(major, minor, patch),
             semVerProxy.latestVersion()
-        );	
+        );
     }
 
     function testFuzz_subscribe(address caller) public {
@@ -292,7 +291,10 @@ contract SemVerProxyTest is Test {
         assertEq(implementation.x(), release2.ANOTHA_WILL_BE_X());
     }
 
-    function _compareVersions(Version memory v0, Version memory v1) internal {
+    function _compareVersions(
+        Version memory v0,
+        Version memory v1
+    ) internal pure {
         assertEq(
             EncodedVersion.unwrap(v0.encode()),
             EncodedVersion.unwrap(v1.encode())

diff --git a/test/InvariantSemVerProxy.t.sol → test/SemVerProxyInv.t.sol b/test/InvariantSemVerProxy.t.sol → test/SemVerProxyInv.t.sol
@@ -1,4 +1,4 @@
-pragma solidity ^0.8.28;
+pragma solidity 0.8.30;
 
 import {ProxyAdmin} from "openzeppelin-contracts/contracts/proxy/transparent/TransparentUpgradeableProxy.sol";
 import {Versioning, Version, EncodedVersion} from "../src/lib/Versioning.sol";
@@ -7,7 +7,7 @@ import {X, Y, Z} from "./mocks/VersionedContract.sol";
 import {SemVerProxy} from "../src/SemVerProxy.sol";
 import {Test, Vm} from "forge-std/Test.sol";
 
-contract InvariantSemVerProxyTest is Test {
+contract SemVerProxyInv is Test {
     using {Versioning.encode} for Version;
 
     address latestRelease;

diff --git a/test/libs/Clients.t.sol b/test/libs/Clients.t.sol
@@ -1,4 +1,4 @@
-pragma solidity ^0.8.28;
+pragma solidity 0.8.30;
 
 import {Client, Clients} from "../../src/lib/Clients.sol";
 import {Test} from "forge-std/Test.sol";

diff --git a/test/libs/Versioning.t.sol b/test/libs/Versioning.t.sol
@@ -1,4 +1,4 @@
-pragma solidity ^0.8.28;
+pragma solidity 0.8.30;
 
 import {Version, Versioning, EncodedVersion} from "../../src/lib/Versioning.sol";
 import {Test} from "forge-std/Test.sol";

diff --git a/test/mocks/BreakingContract.sol b/test/mocks/BreakingContract.sol
@@ -1,9 +1,8 @@
-pragma solidity ^0.8.28;
+pragma solidity 0.8.30;
 
 import {Version} from "../../src/lib/Versioning.sol";
 
-contract Breaking {
-    uint256[100] private __gap;
+contract Breaking layout at 1_000 {
     Version public latestVersion_;
 
     function setVersion() external {

diff --git a/test/mocks/VersionedContract.sol b/test/mocks/VersionedContract.sol
@@ -1,4 +1,4 @@
-pragma solidity ^0.8.28;
+pragma solidity 0.8.30;
 
 contract X {
     uint256 public constant WILL_BE_X = 228;