[Gradle] Implement SourceSetTreeClassifier API

- This new API will be configurable for 'External Kotlin Targets'
- This change also moves targetHierarchy.android {} into the androidTarget
to avoid potential confusion around the KGP managed AndroidTarget vs
the Google implementation.

KT-58710

libraries/tools/kotlin-gradle-plugin-api/api/kotlin-gradle-plugin-api.api

@@ -142,16 +142,6 @@ public abstract interface class org/jetbrains/kotlin/gradle/dsl/KaptJavacOption
 	public abstract fun option (Ljava/lang/Object;Ljava/lang/Object;)V
 }
 
-public abstract interface class org/jetbrains/kotlin/gradle/dsl/KotlinAndroidTargetHierarchyDsl {
-	public abstract fun getInstrumentedTest ()Lorg/jetbrains/kotlin/gradle/dsl/KotlinAndroidVariantHierarchyDsl;
-	public abstract fun getMain ()Lorg/jetbrains/kotlin/gradle/dsl/KotlinAndroidVariantHierarchyDsl;
-	public abstract fun getUnitTest ()Lorg/jetbrains/kotlin/gradle/dsl/KotlinAndroidVariantHierarchyDsl;
-}
-
-public abstract interface class org/jetbrains/kotlin/gradle/dsl/KotlinAndroidVariantHierarchyDsl {
-	public abstract fun getSourceSetTree ()Lorg/gradle/api/provider/Property;
-}
-
 public abstract interface class org/jetbrains/kotlin/gradle/dsl/KotlinArtifact : org/gradle/api/Named, org/gradle/api/plugins/ExtensionAware {
 	public abstract fun getArtifactName ()Ljava/lang/String;
 	public abstract fun getModules ()Ljava/util/Set;
@@ -530,11 +520,9 @@ public abstract interface class org/jetbrains/kotlin/gradle/dsl/KotlinNativeXCFr
 }
 
 public abstract interface class org/jetbrains/kotlin/gradle/dsl/KotlinTargetHierarchyDsl {
-	public abstract fun android (Lkotlin/jvm/functions/Function1;)V
 	public abstract fun apply (Lorg/jetbrains/kotlin/gradle/plugin/KotlinTargetHierarchyDescriptor;Lkotlin/jvm/functions/Function1;)V
 	public abstract fun custom (Lkotlin/jvm/functions/Function1;)V
 	public abstract fun default (Lkotlin/jvm/functions/Function1;)V
-	public abstract fun getAndroid ()Lorg/jetbrains/kotlin/gradle/dsl/KotlinAndroidTargetHierarchyDsl;
 }
 
 public final class org/jetbrains/kotlin/gradle/dsl/KotlinTargetHierarchyDsl$DefaultImpls {
@@ -1105,6 +1093,7 @@ public abstract interface class org/jetbrains/kotlin/gradle/plugin/KotlinTargetH
 	public abstract fun withAndroidNativeArm64 ()V
 	public abstract fun withAndroidNativeX64 ()V
 	public abstract fun withAndroidNativeX86 ()V
+	public abstract fun withAndroidTarget ()V
 	public abstract fun withApple ()V
 	public abstract fun withCompilations (Lkotlin/jvm/functions/Function1;)V
 	public abstract fun withIos ()V

libraries/tools/kotlin-gradle-plugin-api/src/common/kotlin/org/jetbrains/kotlin/gradle/dsl/KotlinTargetHierarchyDsl.kt

@@ -170,72 +170,4 @@ interface KotlinTargetHierarchyDsl {
      * ```
      */
     fun custom(describe: KotlinTargetHierarchyBuilder.Root.() -> Unit)
-
-    /**
-     * Configure Android specific settings within the context of [KotlinTargetHierarchy].
-     * The difference between Android and other targets is that the build author is free to choose
-     * the names of compilations, whereas Android is using predefined SourceSet names.
-     *
-     * ### Default dependsOn edges
-     * By default, Kotlin Multiplatform will set the following default dependsOn edges:
-     * - `androidMain` -> `commonMain`
-     * - `androidUnitTest` -> `commonTest`
-     *
-     * In this default setup, SourceSets like `androidInstrumentedTest` will *not* dependOn `commonTest`.
-     * This API can be used to change the default behavior
-     *
-     * #### Example 1: Setting up androidInstrumentedTest -> commonTest
-     * This can be done by putting the 'androidInstrumentedTest' variants into the 'test' [SourceSetTree]:
-     * ```kotlin
-     * targetHierarchy.android {
-     *     instrumentedTest.sourceSetTree.set(SourceSetTree.test)
-     * }
-     * ```
-     *
-     * #### Example 2: Setting up androidInstrumentedTest -> commonTest and removing 'unitTests' from the 'test' [SourceSetTree]
-     * ```kotlin
-     * targetHierarchy.android {
-     *     instrumentedTest.sourceSetTree.set(SourceSetTree.test)
-     *     unitTest.sourceSetTree.set(SourceSetTree.unitTest) // ! <- Anything *other* than 'test'
-     * }
-     * ```
-     */
-    @ExperimentalKotlinGradlePluginApi
-    fun android(configure: KotlinAndroidTargetHierarchyDsl.() -> Unit)
-
-    /**
-     * See [android]
-     */
-    @ExperimentalKotlinGradlePluginApi
-    val android: KotlinAndroidTargetHierarchyDsl
-}
-
-
-@ExperimentalKotlinGradlePluginApi
-interface KotlinAndroidTargetHierarchyDsl {
-    val main: KotlinAndroidVariantHierarchyDsl
-    val unitTest: KotlinAndroidVariantHierarchyDsl
-    val instrumentedTest: KotlinAndroidVariantHierarchyDsl
-}
-
-@ExperimentalKotlinGradlePluginApi
-interface KotlinAndroidVariantHierarchyDsl {
-    /**
-     * Configures under which [SourceSetTree] the currently configured Android Variant shall be placed.
-     * e.g.
-     *
-     * ```kotlin
-     * kotlin {
-     *     targetHierarchy.android {
-     *         instrumentedTest.sourceSetTree.set(SourceSetTree.test)
-     *     }
-     * }
-     * ```
-     *
-     * Will ensure that all android instrumented tests (androidInstrumentedTest, androidInstrumentedTestDebug, ...)
-     * will be placed into the 'test' SourceSet tree (with 'commonTest' as root)
-     *
-     * See [KotlinTargetHierarchyDsl.android]
-     */
-    val sourceSetTree: Property<SourceSetTree>
 }

libraries/tools/kotlin-gradle-plugin/api/kotlin-gradle-plugin.api

@@ -231,6 +231,7 @@ public abstract interface class org/jetbrains/kotlin/gradle/plugin/mpp/external/
 	public abstract fun getConfigure ()Lkotlin/jvm/functions/Function1;
 	public abstract fun getDefaultSourceSet ()Lorg/jetbrains/kotlin/gradle/plugin/KotlinSourceSet;
 	public abstract fun getFriendArtifactResolver ()Lorg/jetbrains/kotlin/gradle/plugin/mpp/external/ExternalKotlinCompilationDescriptor$FriendArtifactResolver;
+	public abstract fun getSourceSetTreeClassifier ()Lorg/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier;
 }
 
 public abstract interface class org/jetbrains/kotlin/gradle/plugin/mpp/external/ExternalKotlinCompilationDescriptor$CompilationAssociator {
@@ -254,6 +255,7 @@ public final class org/jetbrains/kotlin/gradle/plugin/mpp/external/ExternalKotli
 	public final fun getCompileTaskName ()Ljava/lang/String;
 	public final fun getDefaultSourceSet ()Lorg/jetbrains/kotlin/gradle/plugin/KotlinSourceSet;
 	public final fun getFriendArtifactResolver ()Lorg/jetbrains/kotlin/gradle/plugin/mpp/external/ExternalKotlinCompilationDescriptor$FriendArtifactResolver;
+	public final fun getSourceSetTreeClassifier ()Lorg/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier;
 	public final fun setCompilationAssociator (Lorg/jetbrains/kotlin/gradle/plugin/mpp/external/ExternalKotlinCompilationDescriptor$CompilationAssociator;)V
 	public final fun setCompilationFactory (Lorg/jetbrains/kotlin/gradle/plugin/mpp/external/ExternalKotlinCompilationDescriptor$CompilationFactory;)V
 	public final fun setCompilationName (Ljava/lang/String;)V
@@ -261,6 +263,7 @@ public final class org/jetbrains/kotlin/gradle/plugin/mpp/external/ExternalKotli
 	public final fun setCompileTaskName (Ljava/lang/String;)V
 	public final fun setDefaultSourceSet (Lorg/jetbrains/kotlin/gradle/plugin/KotlinSourceSet;)V
 	public final fun setFriendArtifactResolver (Lorg/jetbrains/kotlin/gradle/plugin/mpp/external/ExternalKotlinCompilationDescriptor$FriendArtifactResolver;)V
+	public final fun setSourceSetTreeClassifier (Lorg/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier;)V
 }
 
 public final class org/jetbrains/kotlin/gradle/plugin/mpp/external/ExternalKotlinCompilationDescriptorKt {
@@ -312,3 +315,44 @@ public final class org/jetbrains/kotlin/gradle/plugin/mpp/external/ExternalKotli
 	public static final fun ExternalKotlinTargetDescriptor (Lkotlin/jvm/functions/Function1;)Lorg/jetbrains/kotlin/gradle/plugin/mpp/external/ExternalKotlinTargetDescriptor;
 }
 
+public abstract class org/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier {
+}
+
+public final class org/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier$Default : org/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier {
+	public static final field INSTANCE Lorg/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier$Default;
+	public fun toString ()Ljava/lang/String;
+}
+
+public final class org/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier$Name : org/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier {
+	public fun <init> (Ljava/lang/String;)V
+	public final fun component1 ()Ljava/lang/String;
+	public final fun copy (Ljava/lang/String;)Lorg/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier$Name;
+	public static synthetic fun copy$default (Lorg/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier$Name;Ljava/lang/String;ILjava/lang/Object;)Lorg/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier$Name;
+	public fun equals (Ljava/lang/Object;)Z
+	public final fun getName ()Ljava/lang/String;
+	public fun hashCode ()I
+	public fun toString ()Ljava/lang/String;
+}
+
+public final class org/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier$None : org/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier {
+	public static final field INSTANCE Lorg/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier$None;
+	public fun toString ()Ljava/lang/String;
+}
+
+public final class org/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier$Property : org/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier {
+	public fun <init> (Lorg/gradle/api/provider/Property;)V
+	public final fun getProperty ()Lorg/gradle/api/provider/Property;
+	public fun toString ()Ljava/lang/String;
+}
+
+public final class org/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier$Value : org/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier {
+	public fun <init> (Lorg/jetbrains/kotlin/gradle/plugin/KotlinTargetHierarchy$SourceSetTree;)V
+	public final fun component1 ()Lorg/jetbrains/kotlin/gradle/plugin/KotlinTargetHierarchy$SourceSetTree;
+	public final fun copy (Lorg/jetbrains/kotlin/gradle/plugin/KotlinTargetHierarchy$SourceSetTree;)Lorg/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier$Value;
+	public static synthetic fun copy$default (Lorg/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier$Value;Lorg/jetbrains/kotlin/gradle/plugin/KotlinTargetHierarchy$SourceSetTree;ILjava/lang/Object;)Lorg/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier$Value;
+	public fun equals (Ljava/lang/Object;)Z
+	public final fun getTree ()Lorg/jetbrains/kotlin/gradle/plugin/KotlinTargetHierarchy$SourceSetTree;
+	public fun hashCode ()I
+	public fun toString ()Ljava/lang/String;
+}
+

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/dsl/KotlinMultiplatformExtension.kt

@@ -53,7 +53,7 @@ abstract class KotlinMultiplatformExtension(project: Project) :
     }
 
     internal val internalKotlinTargetHierarchy by lazy {
-        KotlinTargetHierarchyDslImpl(project.objects, targets, sourceSets)
+        KotlinTargetHierarchyDslImpl(targets, sourceSets)
     }
 
     @ExperimentalKotlinGradlePluginApi
@@ -76,13 +76,13 @@ abstract class KotlinMultiplatformExtension(project: Project) :
     fun <T : KotlinTarget> targetFromPreset(
         preset: KotlinTargetPreset<T>,
         name: String = preset.name,
-        configure: T.() -> Unit = { }
+        configure: T.() -> Unit = { },
     ): T = configureOrCreate(name, preset, configure)
 
     fun <T : KotlinTarget> targetFromPreset(
         preset: KotlinTargetPreset<T>,
         name: String,
-        configure: Action<T>
+        configure: Action<T>,
     ) = targetFromPreset(preset, name) { configure.execute(this) }
 
     fun <T : KotlinTarget> targetFromPreset(preset: KotlinTargetPreset<T>) = targetFromPreset(preset, preset.name) { }
@@ -100,37 +100,37 @@ interface TargetsFromPresetExtension : NamedDomainObjectCollection<KotlinTarget>
     fun <T : KotlinTarget> fromPreset(
         preset: KotlinTargetPreset<T>,
         name: String,
-        configureAction: T.() -> Unit = {}
+        configureAction: T.() -> Unit = {},
     ): T
 
     fun <T : KotlinTarget> fromPreset(
         preset: KotlinTargetPreset<T>,
-        name: String
+        name: String,
     ): T = fromPreset(preset, name, {})
 
     fun <T : KotlinTarget> fromPreset(
         preset: KotlinTargetPreset<T>,
         name: String,
-        configureAction: Action<T>
+        configureAction: Action<T>,
     ): T
 }
 
 internal abstract class DefaultTargetsFromPresetExtension @Inject constructor(
     private val targetsContainer: () -> KotlinTargetsContainerWithPresets,
-    val targets: NamedDomainObjectCollection<KotlinTarget>
+    val targets: NamedDomainObjectCollection<KotlinTarget>,
 ) : TargetsFromPresetExtension,
     NamedDomainObjectCollection<KotlinTarget> by targets {
 
     override fun <T : KotlinTarget> fromPreset(
         preset: KotlinTargetPreset<T>,
         name: String,
-        configureAction: T.() -> Unit
+        configureAction: T.() -> Unit,
     ): T = targetsContainer().configureOrCreate(name, preset, configureAction)
 
     override fun <T : KotlinTarget> fromPreset(
         preset: KotlinTargetPreset<T>,
         name: String,
-        configureAction: Action<T>
+        configureAction: Action<T>,
     ) = fromPreset(preset, name) {
         configureAction.execute(this)
     }
@@ -142,7 +142,7 @@ internal fun KotlinTarget.isProducedFromPreset(kotlinTargetPreset: KotlinTargetP
 internal fun <T : KotlinTarget> KotlinTargetsContainerWithPresets.configureOrCreate(
     targetName: String,
     targetPreset: KotlinTargetPreset<T>,
-    configure: T.() -> Unit
+    configure: T.() -> Unit,
 ): T {
     val existingTarget = targets.findByName(targetName)
     when {
@@ -172,7 +172,7 @@ internal fun <T : KotlinTarget> KotlinTargetsContainerWithPresets.configureOrCre
 
 internal fun KotlinTargetsContainerWithPresets.configureOrCreateAndroidTargetAndReportDeprecation(
     targetName: String,
-    configure: KotlinAndroidTarget.() -> Unit
+    configure: KotlinAndroidTarget.() -> Unit,
 ): KotlinAndroidTarget {
     val targetPreset = presets.getByName("android") as KotlinAndroidTargetPreset
     val result = configureOrCreate(targetName, targetPreset, configure)

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/KotlinMultiplatformPlugin.kt

@@ -24,6 +24,7 @@ import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinMultiplatformPlugin.Companio
 import org.jetbrains.kotlin.gradle.plugin.mpp.apple.addBuildListenerForXcode
 import org.jetbrains.kotlin.gradle.plugin.mpp.internal.runDeprecationDiagnostics
 import org.jetbrains.kotlin.gradle.plugin.mpp.pm20.util.copyAttributes
+import org.jetbrains.kotlin.gradle.plugin.mpp.targetHierarchy.orNull
 import org.jetbrains.kotlin.gradle.plugin.sources.DefaultLanguageSettingsBuilder
 import org.jetbrains.kotlin.gradle.plugin.sources.checkSourceSetVisibilityRequirements
 import org.jetbrains.kotlin.gradle.plugin.sources.internal
@@ -85,7 +86,7 @@ class KotlinMultiplatformPlugin : Plugin<Project> {
     }
 
     private fun exportProjectStructureMetadataForOtherBuilds(
-        extension: KotlinMultiplatformExtension
+        extension: KotlinMultiplatformExtension,
     ) {
         GlobalProjectStructureMetadataStorage.registerProjectStructureMetadata(extension.project) {
             extension.kotlinProjectStructureMetadata
@@ -168,22 +169,24 @@ class KotlinMultiplatformPlugin : Plugin<Project> {
 
 
     private fun configureSourceSets(project: Project) = with(project.multiplatformExtension) {
-        val production = sourceSets.create(KotlinSourceSet.COMMON_MAIN_SOURCE_SET_NAME)
+        /* Create 'commonMain' and 'commonTest' SourceSets */
-        val test = sourceSets.create(KotlinSourceSet.COMMON_TEST_SOURCE_SET_NAME)
+        sourceSets.create(KotlinSourceSet.COMMON_MAIN_SOURCE_SET_NAME)
+        sourceSets.create(KotlinSourceSet.COMMON_TEST_SOURCE_SET_NAME)
+
+        /* Create default 'dependsOn' to commonMain/commonTest (or even common{SourceSetTree}) */
         targets.all { target ->
             project.launchInStage(KotlinPluginLifecycle.Stage.FinaliseRefinesEdges) {
                 /* Only setup default refines edges when no KotlinTargetHierarchy was applied */
                 if (project.multiplatformExtension.internalKotlinTargetHierarchy.appliedDescriptors.isNotEmpty()) return@launchInStage
 
-                target.compilations.findByName(KotlinCompilation.MAIN_COMPILATION_NAME)?.let { mainCompilation ->
+                target.compilations.forEach { compilation ->
-                    mainCompilation.defaultSourceSet.takeIf { it != production }?.dependsOn(production)
+                    val sourceSetTree = KotlinTargetHierarchy.SourceSetTree.orNull(compilation) ?: return@forEach
-                }
+                    val commonSourceSet = sourceSets.findByName(lowerCamelCaseName("common", sourceSetTree.name)) ?: return@forEach
-
+                    compilation.defaultSourceSet.dependsOn(commonSourceSet)
-                target.compilations.findByName(KotlinCompilation.TEST_COMPILATION_NAME)?.let { testCompilation ->
-                    testCompilation.defaultSourceSet.takeIf { it != test }?.dependsOn(test)
                 }
             }
 
+            /* Report the platform to tbe build stats service */
             val targetName = if (target is KotlinNativeTarget)
                 target.konanTarget.name
             else
@@ -277,7 +280,7 @@ private fun sourcesJarTask(
     project: Project,
     sourceSets: Future<Map<String, Iterable<File>>>,
     taskNamePrefix: String,
-    artifactNameAppendix: String
+    artifactNameAppendix: String,
 ): TaskProvider<Jar> =
     sourcesJarTaskNamed(lowerCamelCaseName(taskNamePrefix, "sourcesJar"), taskNamePrefix, project, sourceSets, artifactNameAppendix)
 

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/external/ExternalKotlinCompilationDescriptor.kt

@@ -12,6 +12,7 @@ import org.jetbrains.kotlin.gradle.plugin.KotlinSourceSet
 import org.jetbrains.kotlin.gradle.plugin.KotlinTarget
 import org.jetbrains.kotlin.gradle.plugin.mpp.DecoratedKotlinCompilation
 import org.jetbrains.kotlin.gradle.plugin.mpp.external.ExternalKotlinCompilationDescriptor.*
+import org.jetbrains.kotlin.gradle.plugin.mpp.targetHierarchy.SourceSetTreeClassifier
 import kotlin.properties.Delegates
 
 /**
@@ -54,6 +55,7 @@ interface ExternalKotlinCompilationDescriptor<T : DecoratedExternalKotlinCompila
     val compilationFactory: CompilationFactory<T>
     val friendArtifactResolver: FriendArtifactResolver<T>?
     val compilationAssociator: CompilationAssociator<T>?
+    val sourceSetTreeClassifier: SourceSetTreeClassifier
     val configure: ((T) -> Unit)?
 }
 
@@ -70,6 +72,7 @@ fun <T : DecoratedExternalKotlinCompilation> ExternalKotlinCompilationDescriptor
             compilationFactory = compilationFactory,
             friendArtifactResolver = friendArtifactResolver,
             compilationAssociator = compilationAssociator,
+            sourceSetTreeClassifier = sourceSetTreeClassifier,
             configure = this.configure
         )
     }
@@ -84,6 +87,8 @@ class ExternalKotlinCompilationDescriptorBuilder<T : DecoratedExternalKotlinComp
     var compilationFactory: CompilationFactory<T> by Delegates.notNull()
     var friendArtifactResolver: FriendArtifactResolver<T>? = null
     var compilationAssociator: CompilationAssociator<T>? = null
+    var sourceSetTreeClassifier: SourceSetTreeClassifier = SourceSetTreeClassifier.Default
+
     internal var configure: ((T) -> Unit)? = null
 
     fun configure(action: (T) -> Unit) = apply {
@@ -101,5 +106,6 @@ private data class ExternalKotlinCompilationDescriptorImpl<T : DecoratedExternal
     override val compilationFactory: CompilationFactory<T>,
     override val friendArtifactResolver: FriendArtifactResolver<T>?,
     override val compilationAssociator: CompilationAssociator<T>?,
+    override val sourceSetTreeClassifier: SourceSetTreeClassifier,
     override val configure: ((T) -> Unit)?,
 ) : ExternalKotlinCompilationDescriptor<T>

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/external/createExternalKotlinCompilation.kt

@@ -12,9 +12,9 @@ import org.jetbrains.kotlin.gradle.plugin.mpp.compilationImpl.DefaultKotlinCompi
 import org.jetbrains.kotlin.gradle.plugin.mpp.compilationImpl.KotlinCompilationAssociator
 import org.jetbrains.kotlin.gradle.plugin.mpp.compilationImpl.KotlinCompilationSourceSetsContainer
 import org.jetbrains.kotlin.gradle.plugin.mpp.compilationImpl.factory.*
-import org.jetbrains.kotlin.gradle.plugin.mpp.compilationImpl.factory.KotlinCompilationImplFactory.KotlinCompilationTaskNamesContainerFactory
 import org.jetbrains.kotlin.gradle.plugin.mpp.decoratedInstance
 import org.jetbrains.kotlin.gradle.plugin.mpp.external.DecoratedExternalKotlinCompilation.Delegate
+import org.jetbrains.kotlin.gradle.plugin.mpp.targetHierarchy.sourceSetTreeClassifier
 import org.jetbrains.kotlin.gradle.tasks.KotlinTasksProvider
 
 /**
@@ -30,7 +30,7 @@ import org.jetbrains.kotlin.gradle.tasks.KotlinTasksProvider
  */
 @ExternalKotlinTargetApi
 fun <T : DecoratedExternalKotlinCompilation> DecoratedExternalKotlinTarget.createCompilation(
-    descriptor: ExternalKotlinCompilationDescriptor<T>
+    descriptor: ExternalKotlinCompilationDescriptor<T>,
 ): T {
     val compilationImplFactory = KotlinCompilationImplFactory(
         compilerOptionsFactory = when (platformType) {
@@ -42,7 +42,7 @@ fun <T : DecoratedExternalKotlinCompilation> DecoratedExternalKotlinTarget.creat
             KotlinPlatformType.wasm -> KotlinMultiplatformCommonCompilerOptionsFactory
         },
         compilationSourceSetsContainerFactory = { _, _ -> KotlinCompilationSourceSetsContainer(descriptor.defaultSourceSet) },
-        compilationTaskNamesContainerFactory = KotlinCompilationTaskNamesContainerFactory { target, compilationName ->
+        compilationTaskNamesContainerFactory = { target, compilationName ->
             val default = DefaultKotlinCompilationTaskNamesContainerFactory.create(target, compilationName)
             default.copy(
                 compileTaskName = descriptor.compileTaskName ?: default.compileTaskName,
@@ -70,6 +70,7 @@ fun <T : DecoratedExternalKotlinCompilation> DecoratedExternalKotlinTarget.creat
 
     val compilationImpl = compilationImplFactory.create(this, descriptor.compilationName)
     val decoratedCompilation = descriptor.compilationFactory.create(Delegate(compilationImpl))
+    decoratedCompilation.sourceSetTreeClassifier = descriptor.sourceSetTreeClassifier
     descriptor.configure?.invoke(decoratedCompilation)
     this.delegate.compilations.add(decoratedCompilation)
 
@@ -83,13 +84,13 @@ fun <T : DecoratedExternalKotlinCompilation> DecoratedExternalKotlinTarget.creat
  */
 @ExternalKotlinTargetApi
 fun <T : DecoratedExternalKotlinCompilation> DecoratedExternalKotlinTarget.createCompilation(
-    descriptor: ExternalKotlinCompilationDescriptorBuilder<T>.() -> Unit
+    descriptor: ExternalKotlinCompilationDescriptorBuilder<T>.() -> Unit,
 ): T {
     return createCompilation(ExternalKotlinCompilationDescriptor(descriptor))
 }
 
 private fun DecoratedExternalKotlinTarget.setupCompileTask(
-    compilation: DecoratedExternalKotlinCompilation
+    compilation: DecoratedExternalKotlinCompilation,
 ) {
     val tasksProvider = KotlinTasksProvider()
     val compilationInfo = KotlinCompilationInfo(compilation)

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/KotlinTargetHierarchy.SourceSetTree+orNull.kt

@@ -1,43 +0,0 @@
-/*
- * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
- * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
- */
-
-package org.jetbrains.kotlin.gradle.plugin.mpp.targetHierarchy
-
-import org.jetbrains.kotlin.gradle.dsl.kotlinExtension
-import org.jetbrains.kotlin.gradle.dsl.multiplatformExtension
-import org.jetbrains.kotlin.gradle.dsl.multiplatformExtensionOrNull
-import org.jetbrains.kotlin.gradle.plugin.KotlinCompilation
-import org.jetbrains.kotlin.gradle.plugin.KotlinTargetHierarchy.SourceSetTree
-import org.jetbrains.kotlin.gradle.plugin.awaitFinalValue
-import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinAndroidTarget
-import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinJvmAndroidCompilation
-import org.jetbrains.kotlin.gradle.plugin.sources.android.AndroidVariantType
-import org.jetbrains.kotlin.gradle.plugin.sources.android.type
-
-internal suspend fun SourceSetTree.Companion.orNull(compilation: KotlinCompilation<*>): SourceSetTree? =
-    when (compilation) {
-        is KotlinJvmAndroidCompilation -> orNull(compilation.target, compilation.androidVariant.type)
-        else -> when (compilation.name) {
-            "main" -> main
-            "test" -> test
-            else -> SourceSetTree(compilation.name)
-        }
-    }
-
-internal suspend fun SourceSetTree.Companion.orNull(
-    target: KotlinAndroidTarget,
-    variantType: AndroidVariantType
-): SourceSetTree? {
-    val multiplatform = target.project.multiplatformExtensionOrNull ?: return null
-    return when (variantType) {
-        AndroidVariantType.Main ->
-            multiplatform.targetHierarchy.android.main.sourceSetTree.awaitFinalValue() ?: main
-        AndroidVariantType.UnitTest ->
-            multiplatform.targetHierarchy.android.unitTest.sourceSetTree.awaitFinalValue() ?: test
-        AndroidVariantType.InstrumentedTest ->
-            multiplatform.targetHierarchy.android.instrumentedTest.sourceSetTree.awaitFinalValue() ?: instrumentedTest
-        AndroidVariantType.Unknown -> null
-    }
-}

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/KotlinTargetHierarchyBuilderImpl.kt

@@ -61,17 +61,17 @@ private class KotlinTargetHierarchyBuilderRootImpl(
 
 
     override fun sourceSetTrees(vararg tree: KotlinTargetHierarchy.SourceSetTree) {
-        builder.modules = tree.toHashSet()
+        builder.sourceSetTrees = tree.toHashSet()
     }
 
     override fun withSourceSetTree(vararg tree: KotlinTargetHierarchy.SourceSetTree) {
-        builder.modules = builder.modules.orEmpty().plus(tree)
+        builder.sourceSetTrees = builder.sourceSetTrees.orEmpty().plus(tree)
     }
 
     override fun excludeSourceSetTree(vararg tree: KotlinTargetHierarchy.SourceSetTree) {
         val modules = tree.toHashSet()
         if (modules.isEmpty()) return
-        builder.modules = builder.modules.orEmpty() - modules
+        builder.sourceSetTrees = builder.sourceSetTrees.orEmpty() - modules
     }
 }
 
@@ -84,7 +84,7 @@ private class KotlinTargetHierarchyBuilderImpl(
     val children = mutableSetOf<KotlinTargetHierarchyBuilderImpl>()
     val childrenClosure get() = closure { it.children }
 
-    var modules: Set<KotlinTargetHierarchy.SourceSetTree>? = null
+    var sourceSetTrees: Set<KotlinTargetHierarchy.SourceSetTree>? = null
     private var includePredicate: ((KotlinCompilation<*>) -> Boolean) = { false }
     private var excludePredicate: ((KotlinCompilation<*>) -> Boolean) = { false }
 
@@ -104,9 +104,9 @@ private class KotlinTargetHierarchyBuilderImpl(
     }
 
     suspend fun contains(compilation: KotlinCompilation<*>): Boolean {
-        modules?.let { modules ->
+        sourceSetTrees?.let { sourceSetTrees ->
-            val module = KotlinTargetHierarchy.SourceSetTree.orNull(compilation) ?: return false
+            val sourceSetTree = KotlinTargetHierarchy.SourceSetTree.orNull(compilation) ?: return false
-            if (module !in modules) return false
+            if (sourceSetTree !in sourceSetTrees) return false
         }
 
         /* Return eagerly, when compilation is explicitly excluded */

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/KotlinTargetHierarchyDslImpl.kt

@@ -7,16 +7,13 @@ package org.jetbrains.kotlin.gradle.plugin.mpp.targetHierarchy
 
 import org.gradle.api.DomainObjectCollection
 import org.gradle.api.NamedDomainObjectContainer
-import org.gradle.api.model.ObjectFactory
-import org.gradle.api.provider.Property
-import org.jetbrains.kotlin.gradle.dsl.KotlinAndroidTargetHierarchyDsl
-import org.jetbrains.kotlin.gradle.dsl.KotlinAndroidVariantHierarchyDsl
 import org.jetbrains.kotlin.gradle.dsl.KotlinTargetHierarchyDsl
-import org.jetbrains.kotlin.gradle.plugin.*
+import org.jetbrains.kotlin.gradle.plugin.KotlinSourceSet
-import org.jetbrains.kotlin.gradle.utils.property
+import org.jetbrains.kotlin.gradle.plugin.KotlinTarget
+import org.jetbrains.kotlin.gradle.plugin.KotlinTargetHierarchyBuilder
+import org.jetbrains.kotlin.gradle.plugin.KotlinTargetHierarchyDescriptor
 
 internal class KotlinTargetHierarchyDslImpl(
-    objects: ObjectFactory,
     private val targets: DomainObjectCollection<KotlinTarget>,
     private val sourceSets: NamedDomainObjectContainer<KotlinSourceSet>,
 ) : KotlinTargetHierarchyDsl {
@@ -24,8 +21,6 @@ internal class KotlinTargetHierarchyDslImpl(
     private val _appliedDescriptors = mutableListOf<KotlinTargetHierarchyDescriptor>()
     val appliedDescriptors: List<KotlinTargetHierarchyDescriptor> get() = _appliedDescriptors
 
-    override val android: KotlinAndroidTargetHierarchyDsl = KotlinAndroidTargetHierarchyDslImpl(objects)
-
     override fun apply(
         hierarchyDescriptor: KotlinTargetHierarchyDescriptor,
         describeExtension: (KotlinTargetHierarchyBuilder.Root.() -> Unit)?,
@@ -42,21 +37,8 @@ internal class KotlinTargetHierarchyDslImpl(
     override fun custom(describe: KotlinTargetHierarchyBuilder.Root.() -> Unit) {
         apply(KotlinTargetHierarchyDescriptor(describe))
     }
-
-    override fun android(configure: KotlinAndroidTargetHierarchyDsl.() -> Unit) {
-        android.configure()
-    }
 }
 
 private fun KotlinTargetHierarchyDescriptor.extendIfNotNull(describe: (KotlinTargetHierarchyBuilder.Root.() -> Unit)?) =
     if (describe == null) this else extend(describe)
 
-internal class KotlinAndroidTargetHierarchyDslImpl(objects: ObjectFactory) : KotlinAndroidTargetHierarchyDsl {
-    override val main: KotlinAndroidVariantHierarchyDsl = KotlinAndroidVariantHierarchyDslImpl(objects)
-    override val unitTest: KotlinAndroidVariantHierarchyDsl = KotlinAndroidVariantHierarchyDslImpl(objects)
-    override val instrumentedTest: KotlinAndroidVariantHierarchyDsl = KotlinAndroidVariantHierarchyDslImpl(objects)
-}
-
-internal class KotlinAndroidVariantHierarchyDslImpl(objects: ObjectFactory) : KotlinAndroidVariantHierarchyDsl {
-    override val sourceSetTree: Property<KotlinTargetHierarchy.SourceSetTree> = objects.property()
-}

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/targetHierarchy/SourceSetTreeClassifier.kt

@@ -0,0 +1,120 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.gradle.plugin.mpp.targetHierarchy
+
+import org.jetbrains.kotlin.gradle.ExternalKotlinTargetApi
+import org.jetbrains.kotlin.gradle.plugin.KotlinCompilation
+import org.jetbrains.kotlin.gradle.plugin.KotlinTargetHierarchy
+import org.jetbrains.kotlin.gradle.plugin.KotlinTargetHierarchy.SourceSetTree
+import org.jetbrains.kotlin.gradle.plugin.awaitFinalValue
+import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinJvmAndroidCompilationFactory
+import org.jetbrains.kotlin.tooling.core.extrasLazyProperty
+
+/**
+ * Classifier providing the corresponding [SourceSetTree] associated with any given [KotlinCompilation]
+ *
+ * ### Example: Overwriting 'test' compilations [SourceSetTreeClassifier]:
+ * Consider the following setup:
+ * ```kotlin
+ * kotlin {
+ *     val testCompilation = jvm().compilations.getByName("test")
+ * }
+ * ```
+ *
+ * In this example, we know that the 'jvm/test' compilation will have a 'jvmTest' SourceSet which
+ * will depend on 'commonTest' and therefore is part of the 'test' [SourceSetTree].
+ *
+ * When another [SourceSetTreeClassifier] is specified, this behaviour is changed.
+ * Using the External Kotlin Target API:
+ * ```kotlin
+ *   myTarget.createCompilation {
+ *         compilationName = "test"
+ *         sourceSetTreeClassifier = SourceSetTreeClassifier.Name("unitTest")
+ *   }
+ * ```
+ *
+ * This will create a compilation called 'test' which however will be considered part of the 'unitTest' SourceSetTree.
+ * The SourceSet of this 'jvm/test' compilation will still be called 'jvmTest' but since its part of the 'unitTest [SourceSetTree],
+ * there will not be a dependsOn edge to 'commonTest', but (if present) 'commonUnitTest'
+ */
+@ExternalKotlinTargetApi
+sealed class SourceSetTreeClassifier {
+
+    /**
+     * Default Classifier: The name of the compilation will be used to infer the [SourceSetTree]:
+     * 'main' compilations will be part of [SourceSetTree.main]
+     * 'test' compilations will be part of [SourceSetTree.test]
+     * ...
+     */
+    @ExternalKotlinTargetApi
+    object Default : SourceSetTreeClassifier() {
+        override fun toString(): String = "Default"
+    }
+
+    /**
+     * Indicates that the given compilations is not part of any 'named' [SourceSetTree].
+     * Neither [KotlinTargetHierarchy] will be applied nor default dependsOn edges shall be set.
+     */
+    @ExternalKotlinTargetApi
+    object None : SourceSetTreeClassifier() {
+        override fun toString(): String = "None"
+    }
+
+    /**
+     * Predefined [SourceSetTree] using the [tree] specified.
+     */
+    @ExternalKotlinTargetApi
+    data class Value(val tree: SourceSetTree) : SourceSetTreeClassifier()
+
+    /**
+     * Predefined [SourceSetTree] using the [name] specified
+     */
+    @ExternalKotlinTargetApi
+    data class Name(val name: String) : SourceSetTreeClassifier()
+
+    /**
+     * Wrapper around [org.gradle.api.provider.Property] of a given [SourceSetTree] in order to
+     * make the [SourceSetTree] configurable.
+     */
+    @ExternalKotlinTargetApi
+    class Property(val property: org.gradle.api.provider.Property<SourceSetTree>) : SourceSetTreeClassifier() {
+        override fun toString(): String {
+            return property.toString()
+        }
+    }
+
+    internal suspend fun classify(compilation: KotlinCompilation<*>): SourceSetTree? {
+        return when (this) {
+            is Default -> SourceSetTree(compilation.name)
+            is Property -> property.awaitFinalValue()
+            is Value -> tree
+            is Name -> SourceSetTree(name)
+            is None -> null
+        }
+    }
+}
+
+/**
+ * Returns the classifier configured for a given compilation.
+ * This is writable, as Android requires overwriting of this default behaviour.
+ *
+ * - The KGP maintained target will set the classifier within the [KotlinJvmAndroidCompilationFactory]
+ * - The external Android target will set this classifier within the 'createCompilation'
+ *
+ * It is therefore safe to access this value as soon as a compilation is provided
+ */
+internal var KotlinCompilation<*>.sourceSetTreeClassifier: SourceSetTreeClassifier by extrasLazyProperty {
+    SourceSetTreeClassifier.Default
+}
+
+
+/**
+ * Returns the [SourceSetTree] of a given [KotlinCompilation]:
+ * Uses the [sourceSetTreeClassifier] under the hood.
+ * See [SourceSetTreeClassifier]
+ */
+internal suspend fun SourceSetTree.Companion.orNull(compilation: KotlinCompilation<*>) =
+    compilation.sourceSetTreeClassifier.classify(compilation)

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/sources/android/configurator/MultiplatformLayoutV2DependsOnConfigurator.kt

@@ -11,10 +11,9 @@ import org.jetbrains.kotlin.gradle.dsl.kotlinExtension
 import org.jetbrains.kotlin.gradle.dsl.multiplatformExtensionOrNull
 import org.jetbrains.kotlin.gradle.plugin.KotlinPluginLifecycle
 import org.jetbrains.kotlin.gradle.plugin.KotlinSourceSet
-import org.jetbrains.kotlin.gradle.plugin.KotlinTargetHierarchy
+import org.jetbrains.kotlin.gradle.plugin.awaitFinalValue
 import org.jetbrains.kotlin.gradle.plugin.launchInStage
 import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinAndroidTarget
-import org.jetbrains.kotlin.gradle.plugin.mpp.targetHierarchy.orNull
 import org.jetbrains.kotlin.gradle.plugin.sources.android.AndroidBaseSourceSetName
 import org.jetbrains.kotlin.gradle.plugin.sources.android.AndroidVariantType
 import org.jetbrains.kotlin.gradle.plugin.sources.android.type
@@ -38,7 +37,13 @@ internal object MultiplatformLayoutV2DependsOnConfigurator : KotlinAndroidSource
                 return@launchInStage
             }
 
-            val sourceSetTree = KotlinTargetHierarchy.SourceSetTree.orNull(target, variantType) ?: return@launchInStage
+            val sourceSetTree = when (variantType) {
+                AndroidVariantType.Main -> target.targetHierarchy.main.sourceSetTree.awaitFinalValue()
+                AndroidVariantType.UnitTest -> target.targetHierarchy.unitTest.sourceSetTree.awaitFinalValue()
+                AndroidVariantType.InstrumentedTest -> target.targetHierarchy.instrumentedTest.sourceSetTree.awaitFinalValue()
+                AndroidVariantType.Unknown -> null
+            } ?: return@launchInStage
+
             val commonSourceSetName = lowerCamelCaseName("common", sourceSetTree.name)
             val commonSourceSet = target.project.kotlinExtension.sourceSets.findByName(commonSourceSetName) ?: return@launchInStage
             kotlinSourceSet.dependsOn(commonSourceSet)

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/targets/android/KotlinAndroidTarget.kt

@@ -7,14 +7,13 @@
 package org.jetbrains.kotlin.gradle.plugin.mpp
 
 import com.android.build.gradle.api.BaseVariant
-import org.gradle.api.InvalidUserDataException
+import org.gradle.api.*
-import org.gradle.api.Named
-import org.gradle.api.NamedDomainObjectContainer
-import org.gradle.api.Project
 import org.gradle.api.artifacts.Configuration
 import org.gradle.api.attributes.Attribute
 import org.gradle.api.attributes.AttributeContainer
+import org.jetbrains.kotlin.gradle.ExperimentalKotlinGradlePluginApi
 import org.jetbrains.kotlin.gradle.plugin.*
+import org.jetbrains.kotlin.gradle.plugin.KotlinTargetHierarchy.SourceSetTree
 import org.jetbrains.kotlin.gradle.plugin.mpp.pm20.util.copyAttributes
 import org.jetbrains.kotlin.gradle.utils.dashSeparatedName
 import org.jetbrains.kotlin.gradle.utils.forAllAndroidVariants
@@ -26,7 +25,7 @@ import javax.inject.Inject
 
 abstract class KotlinAndroidTarget @Inject constructor(
     final override val targetName: String,
-    project: Project
+    project: Project,
 ) : AbstractKotlinTarget(project) {
 
     final override val disambiguationClassifier: String = targetName
@@ -37,6 +36,109 @@ abstract class KotlinAndroidTarget @Inject constructor(
     override val compilations: NamedDomainObjectContainer<out KotlinJvmAndroidCompilation> =
         project.container(KotlinJvmAndroidCompilation::class.java)
 
+    /**
+     * Configure Android specific settings within the context of [KotlinTargetHierarchy].
+     * The difference between Android and other targets is that the build author is free to choose
+     * the names of compilations, whereas Android is using predefined SourceSet names.
+     *
+     * ### Default dependsOn edges
+     * By default, Kotlin Multiplatform will set the following default dependsOn edges:
+     * - `androidMain` -> `commonMain`
+     * - `androidUnitTest` -> `commonTest`
+     *
+     * In this default setup, SourceSets like `androidInstrumentedTest` will *not* dependOn `commonTest`.
+     * This API can be used to change the default behavior
+     *
+     * #### Example 1: Setting up androidInstrumentedTest -> commonTest
+     * This can be done by putting the 'androidInstrumentedTest' variants into the 'test' [SourceSetTree]:
+     * ```kotlin
+     * androidTarget().targetHierarchy {
+     *     instrumentedTest.sourceSetTree.set(SourceSetTree.test)
+     * }
+     * ```
+     *
+     * #### Example 2: Setting up androidInstrumentedTest -> commonTest and removing 'unitTests' from the 'test' [SourceSetTree]
+     * ```kotlin
+     * androidTarget().targetHierarchy {
+     *     instrumentedTest.sourceSetTree.set(SourceSetTree.test)
+     *     unitTest.sourceSetTree.set(SourceSetTree.unitTest) // ! <- Anything *other* than 'test'
+     * }
+     * ```
+     */
+    @ExperimentalKotlinGradlePluginApi
+    val targetHierarchy: KotlinAndroidTargetHierarchyDsl = KotlinAndroidTargetHierarchyDslImpl(project.objects).apply {
+        main.sourceSetTree.convention(SourceSetTree.main)
+        unitTest.sourceSetTree.convention(SourceSetTree.test)
+        instrumentedTest.sourceSetTree.convention(SourceSetTree.instrumentedTest)
+    }
+
+    /**
+     * Configure Android specific settings within the context of [KotlinTargetHierarchy].
+     * The difference between Android and other targets is that the build author is free to choose
+     * the names of compilations, whereas Android is using predefined SourceSet names.
+     *
+     * ### Default dependsOn edges
+     * By default, Kotlin Multiplatform will set the following default dependsOn edges:
+     * - `androidMain` -> `commonMain`
+     * - `androidUnitTest` -> `commonTest`
+     *
+     * In this default setup, SourceSets like `androidInstrumentedTest` will *not* dependOn `commonTest`.
+     * This API can be used to change the default behavior
+     *
+     * #### Example 1: Setting up androidInstrumentedTest -> commonTest
+     * This can be done by putting the 'androidInstrumentedTest' variants into the 'test' [SourceSetTree]:
+     * ```kotlin
+     * androidTarget().targetHierarchy {
+     *     instrumentedTest.sourceSetTree.set(SourceSetTree.test)
+     * }
+     * ```
+     *
+     * #### Example 2: Setting up androidInstrumentedTest -> commonTest and removing 'unitTests' from the 'test' [SourceSetTree]
+     * ```kotlin
+     * androidTarget().targetHierarchy {
+     *     instrumentedTest.sourceSetTree.set(SourceSetTree.test)
+     *     unitTest.sourceSetTree.set(SourceSetTree.unitTest) // ! <- Anything *other* than 'test'
+     * }
+     * ```
+     */
+    @ExperimentalKotlinGradlePluginApi
+    fun targetHierarchy(configure: Action<KotlinAndroidTargetHierarchyDsl>) {
+        configure.execute(targetHierarchy)
+    }
+
+    /**
+     * Configure Android specific settings within the context of [KotlinTargetHierarchy].
+     * The difference between Android and other targets is that the build author is free to choose
+     * the names of compilations, whereas Android is using predefined SourceSet names.
+     *
+     * ### Default dependsOn edges
+     * By default, Kotlin Multiplatform will set the following default dependsOn edges:
+     * - `androidMain` -> `commonMain`
+     * - `androidUnitTest` -> `commonTest`
+     *
+     * In this default setup, SourceSets like `androidInstrumentedTest` will *not* dependOn `commonTest`.
+     * This API can be used to change the default behavior
+     *
+     * #### Example 1: Setting up androidInstrumentedTest -> commonTest
+     * This can be done by putting the 'androidInstrumentedTest' variants into the 'test' [SourceSetTree]:
+     * ```kotlin
+     * androidTarget().targetHierarchy {
+     *     instrumentedTest.sourceSetTree.set(SourceSetTree.test)
+     * }
+     * ```
+     *
+     * #### Example 2: Setting up androidInstrumentedTest -> commonTest and removing 'unitTests' from the 'test' [SourceSetTree]
+     * ```kotlin
+     * androidTarget().targetHierarchy {
+     *     instrumentedTest.sourceSetTree.set(SourceSetTree.test)
+     *     unitTest.sourceSetTree.set(SourceSetTree.unitTest) // ! <- Anything *other* than 'test'
+     * }
+     * ```
+     */
+    @ExperimentalKotlinGradlePluginApi
+    fun targetHierarchy(configure: KotlinAndroidTargetHierarchyDsl.() -> Unit) {
+        targetHierarchy.configure()
+    }
 
     /** Names of the Android library variants that should be published from the target's project within the default publications which are
      * set up if the `maven-publish` Gradle plugin is applied.
@@ -241,7 +343,7 @@ abstract class KotlinAndroidTarget @Inject constructor(
     private fun createSourcesElementsIfNeeded(
         variantName: String,
         apiElementsConfigurationName: String,
-        sourcesElementsConfigurationName: String
+        sourcesElementsConfigurationName: String,
     ): Configuration {
         val existingConfiguration = project.configurations.findByName(sourcesElementsConfigurationName)
         if (existingConfiguration != null) return existingConfiguration
@@ -261,7 +363,7 @@ abstract class KotlinAndroidTarget @Inject constructor(
     /** We filter this variant out as it is never requested on the consumer side, while keeping it leads to ambiguity between Android and
      * JVM variants due to non-nesting sets of unmatched attributes. */
     private fun filterOutAndroidVariantAttribute(
-        attribute: Attribute<*>
+        attribute: Attribute<*>,
     ): Boolean =
         attribute.name != "com.android.build.gradle.internal.attributes.VariantAttr" &&
                 attribute.name != "com.android.build.api.attributes.VariantAttr"
@@ -269,7 +371,7 @@ abstract class KotlinAndroidTarget @Inject constructor(
     private fun filterOutAndroidBuildTypeAttribute(
         it: Attribute<*>,
         valueString: String,
-        isSinglePublishedVariant: Boolean
+        isSinglePublishedVariant: Boolean,
     ) = when {
         PropertiesProvider(project).keepAndroidBuildTypeAttribute -> true
         it.name != "com.android.build.api.attributes.BuildTypeAttr" -> true
@@ -281,6 +383,7 @@ abstract class KotlinAndroidTarget @Inject constructor(
     }
 
     private fun filterOutAndroidAgpVersionAttribute(
-        attribute: Attribute<*>
+        attribute: Attribute<*>,
     ): Boolean = attribute.name != "com.android.build.api.attributes.AgpVersionAttr"
 }
+

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/targets/android/KotlinAndroidTargetHierarchyDsl.kt

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+@file:Suppress("PackageDirectoryMismatch") // Old package for compatibility
+
+package org.jetbrains.kotlin.gradle.plugin.mpp
+
+import org.gradle.api.model.ObjectFactory
+import org.gradle.api.provider.Property
+import org.jetbrains.kotlin.gradle.ExperimentalKotlinGradlePluginApi
+import org.jetbrains.kotlin.gradle.dsl.KotlinTargetHierarchyDsl
+import org.jetbrains.kotlin.gradle.plugin.KotlinTargetHierarchy
+import org.jetbrains.kotlin.gradle.plugin.KotlinTargetHierarchy.SourceSetTree
+import org.jetbrains.kotlin.gradle.utils.property
+
+@ExperimentalKotlinGradlePluginApi
+interface KotlinAndroidTargetHierarchyDsl {
+    val main: KotlinAndroidVariantHierarchyDsl
+    val unitTest: KotlinAndroidVariantHierarchyDsl
+    val instrumentedTest: KotlinAndroidVariantHierarchyDsl
+}
+
+
+@ExperimentalKotlinGradlePluginApi
+interface KotlinAndroidVariantHierarchyDsl {
+    /**
+     * Configures under which [SourceSetTree] the currently configured Android Variant shall be placed.
+     * e.g.
+     *
+     * ```kotlin
+     * kotlin {
+     *     targetHierarchy.android {
+     *         instrumentedTest.sourceSetTree.set(SourceSetTree.test)
+     *     }
+     * }
+     * ```
+     *
+     * Will ensure that all android instrumented tests (androidInstrumentedTest, androidInstrumentedTestDebug, ...)
+     * will be placed into the 'test' SourceSet tree (with 'commonTest' as root)
+     *
+     * See [KotlinTargetHierarchyDsl.android]
+     */
+    val sourceSetTree: Property<SourceSetTree>
+}
+
+internal class KotlinAndroidTargetHierarchyDslImpl(objects: ObjectFactory) : KotlinAndroidTargetHierarchyDsl {
+    override val main: KotlinAndroidVariantHierarchyDsl = KotlinAndroidVariantHierarchyDslImpl(objects)
+    override val unitTest: KotlinAndroidVariantHierarchyDsl = KotlinAndroidVariantHierarchyDslImpl(objects)
+    override val instrumentedTest: KotlinAndroidVariantHierarchyDsl = KotlinAndroidVariantHierarchyDslImpl(objects)
+}
+
+internal class KotlinAndroidVariantHierarchyDslImpl(objects: ObjectFactory) : KotlinAndroidVariantHierarchyDsl {
+    override val sourceSetTree: Property<SourceSetTree> = objects.property()
+}

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/targets/jvm/KotlinJvmAndroidCompilationFactory.kt

@@ -12,10 +12,15 @@ import org.jetbrains.kotlin.gradle.plugin.mpp.compilationImpl.KotlinAndroidCompi
 import org.jetbrains.kotlin.gradle.plugin.mpp.compilationImpl.factory.AndroidCompilationSourceSetsContainerFactory
 import org.jetbrains.kotlin.gradle.plugin.mpp.compilationImpl.factory.KotlinCompilationImplFactory
 import org.jetbrains.kotlin.gradle.plugin.mpp.compilationImpl.factory.KotlinJvmCompilerOptionsFactory
+import org.jetbrains.kotlin.gradle.plugin.mpp.targetHierarchy.SourceSetTreeClassifier
+import org.jetbrains.kotlin.gradle.plugin.mpp.targetHierarchy.SourceSetTreeClassifier.Property
+import org.jetbrains.kotlin.gradle.plugin.mpp.targetHierarchy.sourceSetTreeClassifier
+import org.jetbrains.kotlin.gradle.plugin.sources.android.AndroidVariantType
+import org.jetbrains.kotlin.gradle.plugin.sources.android.type
 
 class KotlinJvmAndroidCompilationFactory internal constructor(
     override val target: KotlinAndroidTarget,
-    private val variant: BaseVariant
+    private val variant: BaseVariant,
 ) : KotlinCompilationFactory<KotlinJvmAndroidCompilation> {
 
     override val itemClass: Class<KotlinJvmAndroidCompilation>
@@ -34,6 +39,17 @@ class KotlinJvmAndroidCompilationFactory internal constructor(
     )
 
     override fun create(name: String): KotlinJvmAndroidCompilation {
-        return project.objects.newInstance(itemClass, compilationImplFactory.create(target, name), variant)
+        return project.objects.newInstance(itemClass, compilationImplFactory.create(target, name), variant).also { compilation ->
+            configureSourceSetTreeClassifier(compilation)
+        }
+    }
+
+    private fun configureSourceSetTreeClassifier(compilation: KotlinJvmAndroidCompilation) {
+        compilation.sourceSetTreeClassifier = when (variant.type) {
+            AndroidVariantType.Main -> Property(target.targetHierarchy.main.sourceSetTree)
+            AndroidVariantType.UnitTest -> Property(target.targetHierarchy.unitTest.sourceSetTree)
+            AndroidVariantType.InstrumentedTest -> Property(target.targetHierarchy.instrumentedTest.sourceSetTree)
+            AndroidVariantType.Unknown -> SourceSetTreeClassifier.None
+        }
     }
 }

libraries/tools/kotlin-gradle-plugin/src/functionalTest/kotlin/org/jetbrains/kotlin/gradle/unitTests/ExternalKotlinTargetApiTests.kt

@@ -0,0 +1,92 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+@file:Suppress("FunctionName", "DuplicatedCode")
+
+package org.jetbrains.kotlin.gradle.unitTests
+
+import org.jetbrains.kotlin.gradle.dsl.multiplatformExtension
+import org.jetbrains.kotlin.gradle.plugin.KotlinPlatformType
+import org.jetbrains.kotlin.gradle.plugin.KotlinPluginLifecycle
+import org.jetbrains.kotlin.gradle.plugin.KotlinTargetHierarchy.SourceSetTree
+import org.jetbrains.kotlin.gradle.plugin.launchInStage
+import org.jetbrains.kotlin.gradle.plugin.mpp.external.*
+import org.jetbrains.kotlin.gradle.plugin.mpp.external.ExternalKotlinCompilationDescriptor.CompilationFactory
+import org.jetbrains.kotlin.gradle.plugin.mpp.external.ExternalKotlinTargetDescriptor.TargetFactory
+import org.jetbrains.kotlin.gradle.plugin.mpp.targetHierarchy.SourceSetTreeClassifier
+import org.jetbrains.kotlin.gradle.plugin.mpp.targetHierarchy.orNull
+import org.jetbrains.kotlin.gradle.util.buildProjectWithMPP
+import org.jetbrains.kotlin.gradle.util.runLifecycleAwareTest
+import org.jetbrains.kotlin.gradle.utils.property
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertNull
+
+class ExternalKotlinTargetApiTests {
+
+    class FakeTarget(delegate: Delegate) : DecoratedExternalKotlinTarget(delegate)
+    class FakeCompilation(delegate: Delegate) : DecoratedExternalKotlinCompilation(delegate)
+
+    val project = buildProjectWithMPP()
+    val kotlin = project.multiplatformExtension
+
+    private fun ExternalKotlinTargetDescriptorBuilder<FakeTarget>.defaults() {
+        targetName = "fake"
+        platformType = KotlinPlatformType.jvm
+        targetFactory = TargetFactory(::FakeTarget)
+    }
+
+    private fun ExternalKotlinCompilationDescriptorBuilder<FakeCompilation>.defaults() {
+        compilationName = "fake"
+        compilationFactory = CompilationFactory(::FakeCompilation)
+        defaultSourceSet = kotlin.sourceSets.maybeCreate("fake")
+    }
+
+    @Test
+    fun `test - sourceSetClassifier - default`() = buildProjectWithMPP().runLifecycleAwareTest {
+        val target = kotlin.createExternalKotlinTarget<FakeTarget> { defaults() }
+        val compilation = target.createCompilation<FakeCompilation> { defaults() }
+
+        assertEquals(SourceSetTree("fake"), SourceSetTree.orNull(compilation))
+    }
+
+    @Test
+    fun `test - sourceSetClassifier - custom name`() = buildProjectWithMPP().runLifecycleAwareTest {
+        val target = kotlin.createExternalKotlinTarget<FakeTarget> { defaults() }
+        val compilation = target.createCompilation<FakeCompilation> {
+            defaults()
+            sourceSetTreeClassifier = SourceSetTreeClassifier.Name("mySourceSetTree")
+        }
+
+        assertEquals(SourceSetTree("mySourceSetTree"), SourceSetTree.orNull(compilation))
+    }
+
+    @Test
+    fun `test - sourceSetClassifier - custom property`() = buildProjectWithMPP().runLifecycleAwareTest {
+        val myProperty = project.objects.property<SourceSetTree>()
+        val nullProperty = project.objects.property<SourceSetTree>()
+
+        val target = kotlin.createExternalKotlinTarget<FakeTarget> { defaults() }
+
+        val mainCompilation = target.createCompilation<FakeCompilation> {
+            defaults()
+            sourceSetTreeClassifier = SourceSetTreeClassifier.Property(myProperty)
+        }
+
+        val auxCompilation = target.createCompilation<FakeCompilation>() {
+            compilationName = "aux"
+            compilationFactory = CompilationFactory(::FakeCompilation)
+            defaultSourceSet = kotlin.sourceSets.create("aux")
+            sourceSetTreeClassifier = SourceSetTreeClassifier.Property(nullProperty)
+        }
+
+        launchInStage(KotlinPluginLifecycle.Stage.FinaliseDsl) {
+            myProperty.set(SourceSetTree.main)
+        }
+
+        assertEquals(SourceSetTree.main, SourceSetTree.orNull(mainCompilation))
+        assertNull(SourceSetTree.orNull(auxCompilation))
+    }
+}

libraries/tools/kotlin-gradle-plugin/src/functionalTest/kotlin/org/jetbrains/kotlin/gradle/unitTests/KotlinAndroidTargetHierarchyDsl.kt

@@ -15,7 +15,7 @@ import org.jetbrains.kotlin.gradle.plugin.KotlinPluginLifecycle.Stage.AfterFinal
 import org.jetbrains.kotlin.gradle.plugin.awaitFinalValue
 import org.jetbrains.kotlin.gradle.plugin.currentKotlinPluginLifecycle
 import org.jetbrains.kotlin.gradle.plugin.kotlinPluginLifecycle
-import org.jetbrains.kotlin.gradle.plugin.mpp.targetHierarchy.KotlinAndroidVariantHierarchyDslImpl
+import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinAndroidVariantHierarchyDslImpl
 import org.jetbrains.kotlin.gradle.util.*
 import org.junit.Test
 import kotlin.test.assertEquals
@@ -38,7 +38,7 @@ class KotlinAndroidTargetHierarchyDsl {
         afterEvaluate { dsl.sourceSetTree.set(KotlinTargetHierarchy.SourceSetTree("x")) }
         dsl.sourceSetTree.set(KotlinTargetHierarchy.SourceSetTree("-set-before-after-evaluate-"))
         assertEquals("x", dsl.sourceSetTree.awaitFinalValue()?.name)
-        assertEquals(KotlinPluginLifecycle.Stage.FinaliseDsl, currentKotlinPluginLifecycle().stage)
+        assertEquals(KotlinPluginLifecycle.Stage.AfterFinaliseDsl, currentKotlinPluginLifecycle().stage)
     }
 
     @Test
@@ -51,9 +51,7 @@ class KotlinAndroidTargetHierarchyDsl {
 
         val kotlin = project.multiplatformExtension
         project.runLifecycleAwareTest {
-            kotlin.androidTarget()
+            kotlin.androidTarget().targetHierarchy {
-
-            kotlin.targetHierarchy.android {
                 unitTest.sourceSetTree.set(KotlinTargetHierarchy.SourceSetTree.test)
                 instrumentedTest.sourceSetTree.set(KotlinTargetHierarchy.SourceSetTree.test)
             }
@@ -75,9 +73,7 @@ class KotlinAndroidTargetHierarchyDsl {
 
         val kotlin = project.multiplatformExtension
         project.runLifecycleAwareTest {
-            kotlin.androidTarget()
+            kotlin.androidTarget().targetHierarchy {
-
-            kotlin.targetHierarchy.android {
                 unitTest.sourceSetTree.set(KotlinTargetHierarchy.SourceSetTree("xxx"))
                 instrumentedTest.sourceSetTree.set(KotlinTargetHierarchy.SourceSetTree("yyy"))
             }