Include main jar into runtime classpath for Kotlin MPP target

gradle-plugins/compose-desktop-application/src/main/kotlin/org/jetbrains/compose/desktop/application/ApplicationPlugin.kt

@@ -148,21 +148,13 @@ internal fun AbstractJPackageTask.configurePackagingTask(app: Application) {
     launcherMainJar.set(app.mainJar.orNull)
     app._fromFiles.forEach { files.from(it) }
     dependsOn(*app._dependenciesTaskNames.toTypedArray())
-    when (val configSource = app._configurationSource) {
-        is ConfigurationSource.None -> {}
-        is ConfigurationSource.GradleSourceSet -> {
-            val sourceSet = configSource.sourceSet
-            dependsOn(sourceSet.jarTaskName)
-            launcherMainJar.set(app.mainJar.orElse(jarFromJarTaskByName(sourceSet.jarTaskName)))
-            files.from(sourceSet.runtimeClasspath)
-        }
-        is ConfigurationSource.KotlinMppTarget -> {
-            val target = configSource.target
-            dependsOn(target.artifactsTaskName)
-            launcherMainJar.set(app.mainJar.orElse(jarFromJarTaskByName(target.artifactsTaskName)))
-            files.from(target.runtimeFiles())
-        }
+
+    app._configurationSource?.let { configSource ->
+        dependsOn(configSource.jarTaskName)
+        files.from(configSource.runtimeClasspath)
+        launcherMainJar.set(app.mainJar.orElse(configSource.jarTask(project).flatMap { it.archiveFile }))
     }
+
     modules.set(provider { app.nativeDistributions.modules })
     launcherMainClass.set(provider { app.mainClass })
     launcherJvmArgs.set(provider { app.jvmArgs })
@@ -184,27 +176,15 @@ private fun Project.configureRunTask(app: Application) {
         cp.from(app._fromFiles)
         dependsOn(*app._dependenciesTaskNames.toTypedArray())
 
-        when (val configSource = app._configurationSource) {
-            is ConfigurationSource.None -> {}
-            is ConfigurationSource.GradleSourceSet -> {
-                val sourceSet = configSource.sourceSet
-                dependsOn(sourceSet.jarTaskName)
-                cp.from(sourceSet.runtimeClasspath)
-            }
-            is ConfigurationSource.KotlinMppTarget -> {
-                val target = configSource.target
-                dependsOn(target.artifactsTaskName)
-                cp.from(target.runtimeFiles())
-            }
+        app._configurationSource?.let { configSource ->
+            dependsOn(configSource.jarTaskName)
+            cp.from(configSource.runtimeClasspath)
         }
 
         classpath = cp
     }
 }
 
-private fun KotlinTarget.runtimeFiles(): FileCollection =
-    (compilations.getByName("main") as KotlinCompilationToRunnableFiles).runtimeDependencyFiles
-
 private fun Application.javaHomeOrDefault(): String =
     javaHome ?: System.getProperty("java.home")
 

gradle-plugins/compose-desktop-application/src/main/kotlin/org/jetbrains/compose/desktop/application/dsl/Application.kt

@@ -15,7 +15,7 @@ open class Application @Inject constructor(
     val name: String,
     objects: ObjectFactory
 ) {
-    internal var _configurationSource: ConfigurationSource = ConfigurationSource.None
+    internal var _configurationSource: ConfigurationSource? = null
     internal val _fromFiles = objects.fileCollection()
     internal val _dependenciesTaskNames = ArrayList<String>()
 
@@ -28,7 +28,7 @@ open class Application @Inject constructor(
         _configurationSource = ConfigurationSource.KotlinMppTarget(from)
     }
     fun disableDefaultConfiguration() {
-        _configurationSource = ConfigurationSource.None
+        _configurationSource = null
     }
 
     fun fromFiles(vararg files: Any) {

gradle-plugins/compose-desktop-application/src/main/kotlin/org/jetbrains/compose/desktop/application/dsl/ConfigurationSource.kt

@@ -1,10 +1,35 @@
 package org.jetbrains.compose.desktop.application.dsl
 
+import org.gradle.api.Project
+import org.gradle.api.file.FileCollection
 import org.gradle.api.tasks.SourceSet
+import org.gradle.api.tasks.TaskProvider
+import org.gradle.jvm.tasks.Jar
 import org.jetbrains.kotlin.gradle.targets.jvm.KotlinJvmTarget
 
 internal sealed class ConfigurationSource {
-    object None : ConfigurationSource()
-    class GradleSourceSet(val sourceSet: SourceSet) : ConfigurationSource()
-    class KotlinMppTarget(val target: KotlinJvmTarget) : ConfigurationSource()
+    abstract val jarTaskName: String
+    abstract val runtimeClasspath: FileCollection
+    fun jarTask(project: Project): TaskProvider<Jar> =
+        project.tasks.named(jarTaskName, Jar::class.java)
+
+    class GradleSourceSet(val sourceSet: SourceSet) : ConfigurationSource() {
+        override val jarTaskName: String
+            get() = sourceSet.jarTaskName
+
+        override val runtimeClasspath: FileCollection
+            get() = sourceSet.runtimeClasspath
+
+    }
+
+    class KotlinMppTarget(val target: KotlinJvmTarget) : ConfigurationSource() {
+        override val jarTaskName: String
+            get() = target.artifactsTaskName
+
+        override val runtimeClasspath: FileCollection
+            get() = target.project.objects.fileCollection().apply {
+                from(jarTask(target.project).flatMap { it.archiveFile })
+                from(target.compilations.getByName("main").runtimeDependencyFiles)
+            }
+    }
 }