Samples: Swift 6 JNI sample used from Kotlin, with main-actor view models (on swiftlang#938)

.github/workflows/pull_request.yml

@@ -278,6 +278,7 @@ jobs:
           'SwiftAndJavaJarFFMSampleLib',
           'SwiftJavaExtractFFMSampleApp',
           'SwiftJavaExtractJNISampleApp',
+          'SwiftJavaExtractJNIKotlinSampleApp',
         ]
     container:
       image: ${{ (contains(matrix.swift_version, 'nightly') && 'swiftlang/swift') || 'swift' }}:${{ matrix.swift_version }}-${{ matrix.os_version }}
@@ -315,6 +316,7 @@ jobs:
           'SwiftAndJavaJarFFMSampleLib',
           'SwiftJavaExtractFFMSampleApp',
           'SwiftJavaExtractJNISampleApp',
+          'SwiftJavaExtractJNIKotlinSampleApp',
         ]
     steps:
       - uses: actions/checkout@v7

Samples/SwiftJavaExtractJNIKotlinSampleApp/Package.swift

@@ -0,0 +1,53 @@
+// swift-tools-version: 6.1
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+// Swift 6 language mode, with the generated bindings used from Kotlin (src/test/kotlin).
+// KotlinSampleModels is a separate module so types and protocols cross module boundaries.
+let package = Package(
+  name: "SwiftJavaExtractJNIKotlinSampleApp",
+  platforms: [
+    .macOS(.v15)
+  ],
+  products: [
+    .library(name: "KotlinSampleModels", type: .dynamic, targets: ["KotlinSampleModels"]),
+    .library(name: "KotlinSampleLibrary", type: .dynamic, targets: ["KotlinSampleLibrary"]),
+  ],
+  dependencies: [
+    .package(name: "swift-java", path: "../../")
+  ],
+  targets: [
+    .target(
+      name: "KotlinSampleModels",
+      dependencies: [
+        .product(name: "SwiftJava", package: "swift-java")
+      ],
+      exclude: [
+        "swift-java.config"
+      ],
+      swiftSettings: [
+        .swiftLanguageMode(.v6)
+      ],
+      plugins: [
+        .plugin(name: "JExtractSwiftPlugin", package: "swift-java")
+      ]
+    ),
+    .target(
+      name: "KotlinSampleLibrary",
+      dependencies: [
+        .product(name: "SwiftJava", package: "swift-java"),
+        "KotlinSampleModels",
+      ],
+      exclude: [
+        "swift-java.config"
+      ],
+      swiftSettings: [
+        .swiftLanguageMode(.v6)
+      ],
+      plugins: [
+        .plugin(name: "JExtractSwiftPlugin", package: "swift-java")
+      ]
+    ),
+  ]
+)

Samples/SwiftJavaExtractJNIKotlinSampleApp/Sources/KotlinSampleLibrary/Baseline.swift

@@ -0,0 +1,56 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2026 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import KotlinSampleModels
+
+public struct Item: Hashable, Sendable {
+  public var id: String
+  public var count: Int64
+
+  public init(id: String, count: Int64) {
+    self.id = id
+    self.count = count
+  }
+}
+
+public enum Route: Sendable {
+  case home
+  case detail(Item)
+}
+
+public enum StoreError: Error {
+  case notFound
+}
+
+public final class Store: Sendable {
+  public init() {}
+
+  public func item(id: String) throws -> Item {
+    if id.isEmpty { throw StoreError.notFound }
+    return Item(id: id, count: 1)
+  }
+
+  public func load(id: String) async throws -> Item {
+    try item(id: id)
+  }
+
+  public func route(for item: Item) -> Route {
+    .detail(item)
+  }
+
+  /// Takes a type from another module.
+  public func label(_ item: Item, tag: Tag) -> String {
+    "\(tag.name):\(item.id)"
+  }
+}

Samples/SwiftJavaExtractJNIKotlinSampleApp/Sources/KotlinSampleLibrary/MainActorViewModel.swift

@@ -0,0 +1,29 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2026 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+/// View models are main-actor isolated. Their Java bindings stay synchronous and must be called
+/// on the main thread (Compose's UI thread on Android).
+@MainActor
+public final class CounterViewModel {
+  public private(set) var count: Int64 = 0
+  public var title: String
+
+  public init(title: String) {
+    self.title = title
+  }
+
+  public func increment() {
+    count += 1
+  }
+}

Samples/SwiftJavaExtractJNIKotlinSampleApp/Sources/KotlinSampleLibrary/swift-java.config

@@ -0,0 +1,5 @@
+{
+  "javaPackage": "com.example.kotlin",
+  "mode": "jni",
+  "memoryManagementMode": "allowGlobalAutomatic"
+}

Samples/SwiftJavaExtractJNIKotlinSampleApp/Sources/KotlinSampleModels/Tag.swift

@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2026 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+/// A value type declared in its own module and used from another.
+public struct Tag: Sendable {
+  public var name: String
+
+  public init(name: String) {
+    self.name = name
+  }
+}

Samples/SwiftJavaExtractJNIKotlinSampleApp/Sources/KotlinSampleModels/swift-java.config

@@ -0,0 +1,5 @@
+{
+  "javaPackage": "com.example.kotlin.models",
+  "mode": "jni",
+  "memoryManagementMode": "allowGlobalAutomatic"
+}

Samples/SwiftJavaExtractJNIKotlinSampleApp/build.gradle.kts

@@ -0,0 +1,91 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import java.time.Duration
+import utilities.javaLibraryPaths
+import utilities.jextractGeneratedJavaDirs
+import utilities.registerJextractTask
+
+// The generated Java bindings, used from Kotlin: src/test/kotlin has one test file per feature.
+plugins {
+    id("build-logic.java-common-conventions")
+    kotlin("jvm") version "2.4.21"
+}
+
+group = "org.swift.swiftkit"
+version = "1.0-SNAPSHOT"
+
+repositories {
+    mavenCentral()
+}
+
+java {
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of((gradle.extra.properties["swiftJavaJdk"] as? Int) ?: 17))
+    }
+}
+
+val jextract = registerJextractTask {
+    // FIXME: disable prebuilts until swift-syntax isn't broken on 6.2 anymore: https://github.com/swiftlang/swift-java/issues/418
+    val cmdArgs = mutableListOf("build", "--disable-experimental-prebuilts", "--disable-sandbox")
+    if (project.hasProperty("swiftSdk")) {
+        cmdArgs.add("--swift-sdk")
+        cmdArgs.add(project.property("swiftSdk").toString())
+    }
+    cmdArgs
+}
+
+sourceSets {
+    main {
+        java {
+            srcDir(jextract)
+            jextractGeneratedJavaDirs().forEach { srcDir(it) }
+        }
+    }
+}
+
+tasks.build {
+    dependsOn(jextract)
+}
+
+dependencies {
+    implementation(projects.swiftKitCore)
+
+    testImplementation(kotlin("test-junit5"))
+    testImplementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.11.0")
+    testRuntimeOnly(libs.junit.platform.launcher) // TODO: workaround for not finding junit: https://github.com/gradle/gradle/issues/34512
+}
+
+tasks.named<Test>("test") {
+    useJUnitPlatform()
+    // A deadlocked test fails instead of stalling the build.
+    timeout.set(Duration.ofMinutes(2))
+
+    jvmArgs(
+        "--enable-native-access=ALL-UNNAMED",
+        // Include the library paths where our dylibs are that we want to load and call
+        "-Djava.library.path=" + javaLibraryPaths(project.projectDir).joinToString(File.pathSeparator),
+    )
+
+    // Run tests on the process's first thread, which Swift treats as the main actor's thread (as on
+    // Android's UI thread), so main-actor isolated APIs can be called. macOS only.
+    if (System.getProperty("os.name").startsWith("Mac")) {
+        jvmArgs("-XstartOnFirstThread")
+    }
+
+    testLogging {
+        events("failed")
+        exceptionFormat = org.gradle.api.tasks.testing.logging.TestExceptionFormat.FULL
+    }
+}

Samples/SwiftJavaExtractJNIKotlinSampleApp/ci-validate.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+
+set -x
+set -e
+
+# WORKAROUND: prebuilts broken on Swift 6.2.1 and Linux and tests using macros https://github.com/swiftlang/swift-java/issues/418
+if [ "$(uname)" = "Darwin" ]; then
+  DISABLE_EXPERIMENTAL_PREBUILTS=''
+else
+  DISABLE_EXPERIMENTAL_PREBUILTS='--disable-experimental-prebuilts'
+fi
+
+# FIXME: disable prebuilts until prebuilt swift-syntax isn't broken on 6.2 anymore: https://github.com/swiftlang/swift-java/issues/418
+swift build $DISABLE_EXPERIMENTAL_PREBUILTS --disable-sandbox
+
+./gradlew test

Samples/SwiftJavaExtractJNIKotlinSampleApp/gradle.properties

@@ -0,0 +1 @@
+../gradle.properties

Samples/SwiftJavaExtractJNIKotlinSampleApp/src/test/kotlin/com/example/kotlin/BaselineTest.kt

@@ -0,0 +1,60 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2026 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+package com.example.kotlin
+
+import com.example.kotlin.models.Tag
+import kotlinx.coroutines.future.await
+import kotlinx.coroutines.runBlocking
+import org.swift.swiftkit.core.SwiftArena
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertFailsWith
+import kotlin.test.assertIs
+
+class BaselineTest {
+    @Test
+    fun structRoundTrip() {
+        val item = Item.init("a", 2)
+        assertEquals("a", item.id)
+        assertEquals(2, item.count)
+        assertEquals(Item.init("a", 2), item)
+        assertEquals(Item.init("a", 2).hashCode(), item.hashCode())
+    }
+
+    @Test
+    fun throwsBecomesAnException() {
+        val store = Store.init()
+        assertEquals("x", store.item("x").id)
+        assertFailsWith<Exception> { store.item("") }
+    }
+
+    @Test
+    fun asyncIsAFuture() = runBlocking {
+        assertEquals("x", Store.init().load("x").await().id)
+    }
+
+    @Test
+    fun enumWithPayload() {
+        val route = Store.init().route(Item.init("a", 1))
+        val case = route.getCase(SwiftArena.ofAuto())
+        assertIs<Route.Case.Detail>(case)
+        assertEquals("a", case.arg0.id)
+    }
+
+    @Test
+    fun typeFromAnotherModule() {
+        assertEquals("tag:a", Store.init().label(Item.init("a", 1), Tag.init("tag")))
+    }
+}