Run tests on Windows

.github/workflows/tests.yml

@@ -173,3 +173,27 @@ jobs:
 
       - name: swift test
         run: swift test
+
+  windows_tests:
+    name: Windows Tests
+    runs-on: windows-2025
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          # Requires https://github.com/swiftlang/swift-package-manager/issues/6367 so can't use e.g. 6.0.3, 5.10.1, or 5.9.2.
+          - branch: "swift-6.1.3-release"
+            tag: "6.1.3-RELEASE"
+          - branch: "swift-6.2.2-release"
+            tag: "6.2.2-RELEASE"
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Swift
+        uses: compnerd/gha-setup-swift@main
+        with:
+          branch: ${{ matrix.branch }}
+          tag: ${{ matrix.tag }}
+
+      - name: swift test
+        run: swift test

Package.swift

@@ -56,7 +56,16 @@ let package = Package(
         .product(name: "SwiftSyntaxMacros", package: "swift-syntax"),
         .product(name: "SwiftCompilerPlugin", package: "swift-syntax"),
       ],
-      swiftSettings: [.enableExperimentalFeature("StrictConcurrency")]
+      swiftSettings: [
+        .enableExperimentalFeature("StrictConcurrency"),
+        .unsafeFlags(
+            [
+                "-Xfrontend", "-entry-point-function-name",
+                "-Xfrontend", "wWinMain",
+            ],
+            .when(platforms: [.windows])
+        ),
+      ]
     ),
     .testTarget(
       name: "HashableMacroTests",