Add SwiftLint, pre-commit hooks, and CI workflow

.github/workflows/ci.yml

@@ -0,0 +1,64 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+  workflow_dispatch:
+
+concurrency:
+  group: ci-${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build-and-test:
+    runs-on: macos-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Select Xcode
+        uses: maxim-lobanov/setup-xcode@v1
+        with:
+          # This project requires Xcode 26+ (see README Requirements). Pin an exact
+          # version here if `latest-stable` ever resolves below that floor.
+          xcode-version: latest-stable
+
+      - name: Cache SwiftPM dependency sources
+        uses: actions/cache@v4
+        with:
+          # Package.resolved isn't committed (swift-build/swift-tools-protocols float
+          # on `branch: main`), so it always hashes to the same empty match — key off
+          # Package.swift instead. Cache only fetched sources, not .build's compiled
+          # objects, so a stale cache can't silently serve outdated build products
+          # across dependency or toolchain changes; sources just get an incremental
+          # `git fetch` instead of a full clone.
+          path: |
+            ~/Library/Caches/org.swift.swiftpm
+            .build/checkouts
+            .build/repositories
+          key: ${{ runner.os }}-spm-${{ hashFiles('Package.swift') }}
+          restore-keys: |
+            ${{ runner.os }}-spm-
+
+      - name: Build
+        run: swift build
+
+      - name: Run tests
+        run: swift test
+
+  lint:
+    runs-on: macos-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install SwiftLint
+        env:
+          SWIFTLINT_VERSION: "0.63.3" # keep in sync with the version contributors install locally
+        run: |
+          curl -sL "https://github.com/realm/SwiftLint/releases/download/${SWIFTLINT_VERSION}/portable_swiftlint.zip" -o swiftlint.zip
+          unzip -q swiftlint.zip -d "$RUNNER_TEMP/swiftlint-bin"
+          chmod +x "$RUNNER_TEMP/swiftlint-bin/swiftlint"
+          echo "$RUNNER_TEMP/swiftlint-bin" >> "$GITHUB_PATH"
+
+      - name: Lint
+        run: swiftlint lint

.pre-commit-config.yaml

@@ -0,0 +1,10 @@
+repos:
+  - repo: local
+    hooks:
+      - id: swiftlint
+        name: SwiftLint
+        description: Lint staged Swift files with SwiftLint.
+        entry: swiftlint lint
+        language: system
+        files: \.swift$
+        exclude: ^\.build/

.swiftlint.yml

@@ -0,0 +1,47 @@
+included:
+  - Sources
+  - Tests
+
+excluded:
+  - .build
+  - .swiftpm
+
+opt_in_rules:
+  - empty_count
+  - closure_spacing
+  - contains_over_first_not_nil
+  - fatal_error_message
+  - first_where
+  - force_unwrapping
+  - implicitly_unwrapped_optional
+  - last_where
+  - redundant_nil_coalescing
+  - sorted_first_last
+  - unneeded_parentheses_in_closure_argument
+
+disabled_rules:
+  - todo
+
+line_length:
+  warning: 120
+  error: 200
+
+trailing_comma:
+  mandatory_comma: true
+
+identifier_name:
+  excluded:
+    - id
+    - s
+    - t
+    - fm
+    - op
+    - v26_2
+    - v16_0
+    - v16_2_1
+
+force_unwrapping:
+  severity: warning
+
+implicitly_unwrapped_optional:
+  severity: warning

README.md

@@ -110,8 +110,24 @@ swift test
 
 # Build release binary
 swift build -c release
+
+# Lint
+swiftlint lint
 ```
 
+### Pre-commit hooks
+
+This repo uses [pre-commit](https://pre-commit.com) to lint staged Swift files with
+[SwiftLint](https://github.com/realm/SwiftLint) before each commit.
+
+```bash
+brew install pre-commit swiftlint
+pre-commit install
+```
+
+After that, `git commit` runs SwiftLint automatically against whatever `.swift` files are
+staged. Run it manually against everything with `pre-commit run --all-files`.
+
 ### Project layout
 
 ```

Sources/SourceKitXcodeBSP/Bootstrap/BuildServerBootstrap.swift

@@ -323,4 +323,3 @@ public extension BuildServerBootstrap {
         )
     }
 }
-

Sources/SourceKitXcodeBSP/Xcode/XcodePaths.swift

@@ -174,7 +174,7 @@ public struct XcodeVersion: Sendable, CustomStringConvertible {
 
     public init(versionString: String) {
         let parts = versionString.split(separator: ".").compactMap { Int($0) }
-        major = parts.count > 0 ? parts[0] : 0
+        major = !parts.isEmpty ? parts[0] : 0
         minor = parts.count > 1 ? parts[1] : 0
         patch = parts.count > 2 ? parts[2] : 0
     }

Sources/sourcekit-xcode-bsp/SourcekitXcodeBspCommand.swift

@@ -59,4 +59,4 @@ struct Serve: AsyncParsableCommand {
             serviceProvider: serviceProvider
         )
     }
-}
+}

Sources/test-ipc/main.swift

@@ -3,7 +3,7 @@ import SwiftBuild
 
 private final class NopDelegate: SWBPlanningOperationDelegate, @unchecked Sendable {
     func provisioningTaskInputs(targetGUID: String, provisioningSourceData: SWBProvisioningTaskInputsSourceData) async -> SWBProvisioningTaskInputs { .init() }
-    func executeExternalTool(commandLine: [String], workingDirectory: String?, environment: [String : String]) async throws -> SWBExternalToolResult {
+    func executeExternalTool(commandLine: [String], workingDirectory: String?, environment: [String: String]) async throws -> SWBExternalToolResult {
         print("  executeExternalTool: \(commandLine.first ?? "?") (returning .deferred)")
         return .deferred
     }

Tests/SourceKitXcodeBSPTests/Watcher/WorkspaceWatcherTests.swift

@@ -70,7 +70,7 @@ struct WorkspaceChangeFilterTests {
     func rejectsOtherProjects() {
         let filter = WorkspaceChangeFilter(
             allowedPaths: [
-                "/Projects/App/App.xcodeproj/project.pbxproj",
+                "/Projects/App/App.xcodeproj/project.pbxproj"
             ]
         )
 
@@ -110,7 +110,7 @@ struct WorkspaceChangeFilterTests {
         // Even if a checkout path were mistakenly allowlisted, ignore components win.
         let filter = WorkspaceChangeFilter(
             allowedPaths: [
-                "/Projects/App/SourcePackages/checkouts/Dep/Package.swift",
+                "/Projects/App/SourcePackages/checkouts/Dep/Package.swift"
             ]
         )
         #expect(
@@ -126,7 +126,7 @@ struct WorkspaceChangeFilterTests {
         // be an ignore component or reloads never fire.
         let filter = WorkspaceChangeFilter(
             allowedPaths: [
-                "/Users/me/checkouts/MyApp/MyApp.xcodeproj/project.pbxproj",
+                "/Users/me/checkouts/MyApp/MyApp.xcodeproj/project.pbxproj"
             ]
         )
         #expect(

Tests/SourceKitXcodeBSPTests/Xcode/XcodePathsTests.swift

@@ -83,7 +83,7 @@ struct XcodePathsTests {
             .infoPlistInvalid,
             .versionNotFound,
             .unsupportedVersion(XcodeVersion(major: 15, minor: 0)),
-            .swbBuildServiceNotFound
+            .swbBuildServiceNotFound,
         ]
 
         for error in errors {