Prepare intermediate layer of model mapping in Kotlin compilations

Extract all logic and internal model that may be different in different
modes to a separate entity called "compilation details"

libraries/tools/kotlin-gradle-plugin-api/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/KotlinCompilation.kt

@@ -77,9 +77,6 @@ interface KotlinCompilation<out T : KotlinCommonOptions> : Named, HasAttributes,
 
     override fun getName(): String = compilationName
 
-    override val relatedConfigurationNames: List<String>
-        get() = super.relatedConfigurationNames + compileDependencyConfigurationName
-
     val moduleName: String
 
     val disambiguatedName
@@ -100,4 +97,4 @@ val <T : KotlinCommonOptions> KotlinCompilation<T>.runtimeDependencyConfiguratio
 
 interface KotlinCompilationWithResources<T : KotlinCommonOptions> : KotlinCompilation<T> {
     val processResourcesTaskName: String
-}
+}

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/CompilationDetails.kt

@@ -0,0 +1,636 @@
+/*
+ * Copyright 2010-2021 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
+
+import groovy.lang.Closure
+import org.gradle.api.Project
+import org.gradle.api.UnknownTaskException
+import org.gradle.api.artifacts.Dependency
+import org.gradle.api.file.FileCollection
+import org.gradle.api.file.SourceDirectorySet
+import org.gradle.api.plugins.BasePluginExtension
+import org.gradle.api.tasks.SourceSet
+import org.gradle.api.tasks.TaskProvider
+import org.gradle.api.tasks.bundling.AbstractArchiveTask
+import org.jetbrains.kotlin.gradle.dsl.*
+import org.jetbrains.kotlin.gradle.dsl.KotlinJvmOptionsImpl
+import org.jetbrains.kotlin.gradle.plugin.*
+import org.jetbrains.kotlin.gradle.plugin.mpp.internal.KotlinCompilationsModuleGroups
+import org.jetbrains.kotlin.gradle.plugin.mpp.pm20.*
+import org.jetbrains.kotlin.gradle.plugin.mpp.pm20.util.*
+import org.jetbrains.kotlin.gradle.plugin.mpp.pm20.util.newDependencyFilesHolder
+import org.jetbrains.kotlin.gradle.plugin.mpp.pm20.util.ofVariantCompileDependencies
+import org.jetbrains.kotlin.gradle.plugin.mpp.pm20.util.unambiguousNameInProject
+import org.jetbrains.kotlin.gradle.plugin.sources.defaultSourceSetLanguageSettingsChecker
+import org.jetbrains.kotlin.gradle.plugin.sources.getVisibleSourceSetsFromAssociateCompilations
+import org.jetbrains.kotlin.gradle.plugin.sources.resolveAllDependsOnSourceSets
+import org.jetbrains.kotlin.gradle.plugin.sources.withAllDependsOnSourceSets
+import org.jetbrains.kotlin.gradle.targets.js.KotlinJsTarget
+import org.jetbrains.kotlin.gradle.targets.js.ir.KotlinJsIrCompilation
+import org.jetbrains.kotlin.gradle.targets.js.ir.KotlinJsIrTarget
+import org.jetbrains.kotlin.gradle.targets.metadata.getMetadataCompilationForSourceSet
+import org.jetbrains.kotlin.gradle.utils.*
+import org.jetbrains.kotlin.gradle.utils.lowerCamelCaseName
+import org.jetbrains.kotlin.project.model.LanguageSettings
+import java.util.*
+import java.util.concurrent.Callable
+
+interface CompilationDetails<T : KotlinCommonOptions> {
+    val target: KotlinTarget
+
+    val compileDependencyFilesHolder: DependencyFilesHolder
+
+    val kotlinDependenciesHolder: HasKotlinDependencies
+
+    val compilationData: KotlinCompilationData<T>
+
+    fun associateWith(other: CompilationDetails<*>)
+    val associateCompilations: Set<CompilationDetails<*>>
+
+    fun source(sourceSet: KotlinSourceSet)
+
+    val directlyIncludedKotlinSourceSets: MutableSet<KotlinSourceSet>
+    val defaultSourceSetName: String
+
+    @Suppress("UNCHECKED_CAST")
+    val compilation: KotlinCompilation<T>
+        get() = target.compilations.getByName(compilationData.compilationPurpose) as KotlinCompilation<T>
+
+    val defaultSourceSet: KotlinSourceSet
+        get() = target.project.kotlinExtension.sourceSets.getByName(defaultSourceSetName)
+}
+
+interface CompilationDetailsWithRuntime<T : KotlinCommonOptions> : CompilationDetails<T> {
+    val runtimeDependencyFilesHolder: DependencyFilesHolder
+}
+
+internal val CompilationDetails<*>.associateWithTransitiveClosure: Iterable<CompilationDetails<*>>
+    get() = mutableSetOf<CompilationDetails<*>>().apply {
+        fun visit(other: CompilationDetails<*>) {
+            if (add(other)) {
+                other.associateCompilations.forEach(::visit)
+            }
+        }
+        associateCompilations.forEach(::visit)
+    }
+
+open class DefaultCompilationDetails<T : KotlinCommonOptions>(
+    final override val target: KotlinTarget,
+    final override val compilationPurpose: String,
+    createKotlinOptions: DefaultCompilationDetails<*>.() -> T
+) : CompilationDetails<T>, KotlinCompilationData<T> {
+
+    override val kotlinOptions: T by lazy { createKotlinOptions() }
+
+    final override val project: Project
+        get() = target.project
+
+    override val owner: KotlinTarget
+        get() = target
+
+    override val compilationData: KotlinCompilationData<T>
+        get() = this
+
+    override val kotlinDependenciesHolder: HasKotlinDependencies
+        get() = KotlinDependencyConfigurationsHolder(
+            project,
+            lowerCamelCaseName(
+                target.disambiguationClassifier,
+                compilationPurpose.takeIf { it != KotlinCompilation.MAIN_COMPILATION_NAME },
+            )
+        )
+
+    override val compileDependencyFilesHolder: DependencyFilesHolder = project.newDependencyFilesHolder(
+        lowerCamelCaseName(
+            target.disambiguationClassifier,
+            compilationPurpose.takeIf { it != KotlinCompilation.MAIN_COMPILATION_NAME }.orEmpty(),
+            "compileClasspath"
+        )
+    )
+
+    override val directlyIncludedKotlinSourceSets: MutableSet<KotlinSourceSet> = mutableSetOf()
+
+    override val defaultSourceSetName: String
+        get() = lowerCamelCaseName(
+            target.disambiguationClassifier.takeIf { target !is KotlinMetadataTarget },
+            when {
+                isMainCompilationData() && target is KotlinMetadataTarget ->
+                    KotlinSourceSet.COMMON_MAIN_SOURCE_SET_NAME // corner case: main compilation of the metadata target compiles commonMain
+                else -> compilationPurpose
+            }
+        )
+
+    override val compilationClassifier: String?
+        get() = target.disambiguationClassifier
+
+    override val kotlinSourceDirectoriesByFragmentName: Map<String, SourceDirectorySet>
+        get() = directlyIncludedKotlinSourceSets.plus(directlyIncludedKotlinSourceSets.resolveAllDependsOnSourceSets())
+            .associate { it.name to it.kotlin }
+
+    override val compileKotlinTaskName: String
+        get() = lowerCamelCaseName(
+            "compile",
+            compilationPurpose.takeIf { it != KotlinCompilation.MAIN_COMPILATION_NAME },
+            "Kotlin",
+            target.targetName
+        )
+
+    override val compileAllTaskName: String
+        get() = lowerCamelCaseName(target.disambiguationClassifier, compilationPurpose, "classes")
+
+    override val compileDependencyFiles: FileCollection
+        get() = compileDependencyFilesHolder.dependencyFiles
+
+    override val output: KotlinCompilationOutput = DefaultKotlinCompilationOutput(
+        target.project,
+        Callable { target.project.buildDir.resolve("processedResources/${target.targetName}/$compilationPurpose") }
+    )
+
+    override val languageSettings: LanguageSettings
+        get() = project.kotlinExtension.sourceSets.getByName(defaultSourceSetName).languageSettings
+
+    override val platformType: KotlinPlatformType
+        get() = target.platformType
+
+    override val moduleName: String
+        get() = KotlinCompilationsModuleGroups.getModuleLeaderCompilation(this).takeIf { it != this }?.ownModuleName ?: ownModuleName
+
+    override val ownModuleName: String
+        get() {
+            val baseName = project.extensions.getByType(BasePluginExtension::class.java)?.archivesName
+                ?: project.name
+            val suffix = if (isMainCompilationData()) "" else "_$compilationPurpose"
+            return filterModuleName("$baseName$suffix")
+        }
+
+    override val friendPaths: Iterable<FileCollection>
+        get() = mutableListOf<FileCollection>().also { allCollections ->
+            associateWithTransitiveClosure.forEach { allCollections.add(it.compilationData.output.classesDirs) }
+            allCollections.add(friendArtifacts)
+        }
+
+    private val friendArtifactsTask: TaskProvider<AbstractArchiveTask>? by lazy {
+        if (associateWithTransitiveClosure.any { it.compilationData.isMainCompilationData() }) {
+            val archiveTasks = target.project.tasks.withType(AbstractArchiveTask::class.java)
+            if (!archiveTasks.isEmpty()) {
+                try {
+                    archiveTasks.named(target.artifactsTaskName)
+                } catch (e: UnknownTaskException) {
+                    // Native tasks does not extend AbstractArchiveTask
+                    null
+                }
+            } else {
+                null
+            }
+        } else {
+            null
+        }
+    }
+
+    /**
+     * If a compilation is aware of its associate compilations' outputs being added to the classpath in a transformed or packaged way,
+     * it should point to those friend artifact files via this property.
+     */
+    internal open val friendArtifacts: FileCollection
+        get() = with(target.project) {
+            val friendArtifactsTaskProvider = friendArtifactsTask
+            if (friendArtifactsTaskProvider != null) {
+                // In case the main artifact is transitively added to the test classpath via a test dependency on another module
+                // that depends on this module's production part, include the main artifact in the friend artifacts, lazily:
+                files(
+                    Callable {
+                        friendArtifactsTaskProvider.flatMap { it.archiveFile }
+                    }
+                )
+            } else files()
+        }
+
+    override val associateCompilations: Set<CompilationDetails<*>>
+        get() = Collections.unmodifiableSet(_associateCompilations)
+
+    private val _associateCompilations = mutableSetOf<CompilationDetails<*>>()
+
+    override fun associateWith(other: CompilationDetails<*>) {
+        require(other.target == target) { "Only associations between compilations of a single target are supported" }
+        _associateCompilations += other
+        addAssociateCompilationDependencies(other.compilation)
+        KotlinCompilationsModuleGroups.unionModules(this, other.compilationData)
+        _associateCompilations.add(other)
+    }
+
+    @OptIn(ExperimentalStdlibApi::class)
+    protected open fun addAssociateCompilationDependencies(other: KotlinCompilation<*>) = with(compilationData) {
+        /*
+          we add dependencies to compileDependencyConfiguration ('compileClasspath' usually) and runtimeDependency
+          ('runtimeClasspath') instead of modifying respective api/implementation/compileOnly/runtimeOnly configs
+
+          This is needed because api/implementation/compileOnly/runtimeOnly are used in IDE Import and will leak
+          to dependencies of IDE modules. But they are not needed here, because IDE resolution works inherently
+          transitively and symbols from associated compilation will be resolved from source sets of associated
+          compilation itself (moreover, direct dependencies are not equivalent to transitive ones because of
+          resolution order - e.g. in case of FQNs clash, so it's even harmful)
+        */
+        project.dependencies.add(compilation.compileOnlyConfigurationName, project.files(Callable { other.output.classesDirs }))
+        project.dependencies.add(compilation.runtimeOnlyConfigurationName, project.files(Callable { other.output.allOutputs }))
+
+        compilation.compileDependencyConfigurationName.addAllDependenciesFromOtherConfigurations(
+            project,
+            other.apiConfigurationName,
+            other.implementationConfigurationName,
+            other.compileOnlyConfigurationName
+        )
+
+        compilation.runtimeDependencyConfigurationName?.addAllDependenciesFromOtherConfigurations(
+            project,
+            other.apiConfigurationName,
+            other.implementationConfigurationName,
+            other.runtimeOnlyConfigurationName
+        )
+    }
+
+    /**
+     * Adds `allDependencies` of configurations mentioned in `configurationNames` to configuration named [this] in
+     * a lazy manner
+     */
+    private fun String.addAllDependenciesFromOtherConfigurations(project: Project, vararg configurationNames: String) {
+        project.configurations.named(this).configure { receiverConfiguration ->
+            receiverConfiguration.dependencies.addAllLater(
+                project.objects.listProperty(Dependency::class.java).apply {
+                    set(
+                        project.provider {
+                            configurationNames
+                                .map { project.configurations.getByName(it) }
+                                .flatMap { it.allDependencies }
+                        }
+                    )
+                }
+            )
+        }
+    }
+
+
+    override fun source(sourceSet: KotlinSourceSet) {
+        if (directlyIncludedKotlinSourceSets.add(sourceSet)) {
+            target.project.whenEvaluated {
+                addExactSourceSetsEagerly(sourceSet.withAllDependsOnSourceSets())
+            }
+        }
+    }
+
+    open fun addSourcesToCompileTask(sourceSet: KotlinSourceSet, addAsCommonSources: Lazy<Boolean>) =
+        addSourcesToKotlinCompileTask(
+            project,
+            compileKotlinTaskName,
+            sourceSet.customSourceFilesExtensions,
+            addAsCommonSources
+        ) { sourceSet.kotlin }
+
+    internal fun addExactSourceSetsEagerly(sourceSets: Set<KotlinSourceSet>) {
+        with(target.project) {
+            //TODO possibly issue with forced instantiation
+            sourceSets.forEach { sourceSet ->
+                addSourcesToCompileTask(
+                    sourceSet,
+                    addAsCommonSources = lazy {
+                        CompilationSourceSetUtil.sourceSetsInMultipleCompilations(project).contains(sourceSet.name)
+                    }
+                )
+
+                // Use `forced = false` since `api`, `implementation`, and `compileOnly` may be missing in some cases like
+                // old Java & Android projects:
+                addExtendsFromRelation(compilation.apiConfigurationName, sourceSet.apiConfigurationName, forced = false)
+                addExtendsFromRelation(
+                    compilation.implementationConfigurationName,
+                    sourceSet.implementationConfigurationName,
+                    forced = false
+                )
+                addExtendsFromRelation(compilation.compileOnlyConfigurationName, sourceSet.compileOnlyConfigurationName, forced = false)
+
+                if (compilation is KotlinCompilationToRunnableFiles<*>) {
+                    addExtendsFromRelation(compilation.runtimeOnlyConfigurationName, sourceSet.runtimeOnlyConfigurationName, forced = false)
+                }
+
+                if (sourceSet.name != defaultSourceSetName) {
+                    kotlinExtension.sourceSets.findByName(defaultSourceSetName)?.let { defaultSourceSet ->
+                        // Temporary solution for checking consistency across source sets participating in a compilation that may
+                        // not be interconnected with the dependsOn relation: check the settings as if the default source set of
+                        // the compilation depends on the one added to the compilation:
+                        defaultSourceSetLanguageSettingsChecker.runAllChecks(
+                            defaultSourceSet,
+                            sourceSet
+                        )
+                    }
+                }
+            }
+        }
+    }
+}
+
+internal open class DefaultCompilationDetailsWithRuntime<T : KotlinCommonOptions>(
+    target: KotlinTarget,
+    compilationPurpose: String,
+    createKotlinOptions: DefaultCompilationDetails<*>.() -> T
+) : DefaultCompilationDetails<T>(target, compilationPurpose, createKotlinOptions), CompilationDetailsWithRuntime<T> {
+    override val runtimeDependencyFilesHolder: DependencyFilesHolder = project.newDependencyFilesHolder(
+        lowerCamelCaseName(
+            target.disambiguationClassifier,
+            compilationPurpose.takeIf { it != KotlinCompilation.MAIN_COMPILATION_NAME }.orEmpty(),
+            "runtimeClasspath"
+        )
+    )
+}
+
+open class NativeCompilationDetails(
+    target: KotlinTarget,
+    compilationPurpose: String,
+    createKotlinOptions: DefaultCompilationDetails<*>.() -> KotlinCommonOptions
+) : DefaultCompilationDetails<KotlinCommonOptions>(
+    target,
+    compilationPurpose,
+    createKotlinOptions
+) {
+    override val compileDependencyFilesHolder: DependencyFilesHolder = project.newDependencyFilesHolder(
+        lowerCamelCaseName(
+            target.disambiguationClassifier,
+            compilationPurpose.takeIf { it != KotlinCompilation.MAIN_COMPILATION_NAME }.orEmpty(),
+            "compileKlibraries"
+        )
+    )
+
+    override val compileAllTaskName: String
+        get() = lowerCamelCaseName(target.disambiguationClassifier, compilationPurpose, "klibrary")
+
+    override fun addAssociateCompilationDependencies(other: KotlinCompilation<*>) {
+        compileDependencyFilesHolder.dependencyFiles +=
+            other.output.classesDirs + project.filesProvider { other.compileDependencyFiles }
+
+        target.project.configurations.named(compilation.implementationConfigurationName).configure { configuration ->
+            configuration.extendsFrom(target.project.configurations.findByName(other.implementationConfigurationName))
+        }
+    }
+
+    override fun addSourcesToCompileTask(sourceSet: KotlinSourceSet, addAsCommonSources: Lazy<Boolean>) {
+        addSourcesToKotlinNativeCompileTask(project, compileKotlinTaskName, { sourceSet.kotlin }, addAsCommonSources)
+    }
+}
+
+internal open class SharedNativeCompilationDetails(
+    target: KotlinTarget,
+    compilationPurpose: String,
+    createKotlinOptions: DefaultCompilationDetails<*>.() -> KotlinCommonOptions
+) :
+    DefaultCompilationDetails<KotlinCommonOptions>(
+        target,
+        compilationPurpose,
+        createKotlinOptions
+    ) {
+
+    override val friendArtifacts: FileCollection
+        get() = super.friendArtifacts.plus(run {
+            val project = target.project
+            val friendSourceSets = getVisibleSourceSetsFromAssociateCompilations(project, defaultSourceSet).toMutableSet().apply {
+                // TODO: implement proper dependsOn/refines compiler args for Kotlin/Native and pass the dependsOn klibs separately;
+                //       But for now, those dependencies don't have any special semantics, so passing all them as friends works, too
+                addAll(defaultSourceSet.resolveAllDependsOnSourceSets())
+            }
+            project.files(friendSourceSets.mapNotNull { project.getMetadataCompilationForSourceSet(it)?.output?.classesDirs })
+        })
+
+    override fun addSourcesToCompileTask(sourceSet: KotlinSourceSet, addAsCommonSources: Lazy<Boolean>) {
+        addSourcesToKotlinNativeCompileTask(project, compileKotlinTaskName, { sourceSet.kotlin }, addAsCommonSources)
+    }
+}
+
+internal open class VariantMappedCompilationDetails<T : KotlinCommonOptions>(
+    open val variant: KotlinGradleVariantInternal,
+    override val target: KotlinTarget
+) : CompilationDetails<T> {
+
+    @Suppress("UNCHECKED_CAST")
+    override val compilationData: KotlinCompilationData<T>
+        get() = variant.compilationData as KotlinCompilationData<T>
+
+    override val defaultSourceSetName: String
+        get() = variant.unambiguousNameInProject
+
+    override fun source(sourceSet: KotlinSourceSet) {
+        compilation.defaultSourceSet.dependsOn(sourceSet)
+    }
+
+    override fun associateWith(other: CompilationDetails<*>) {
+        throw UnsupportedOperationException("not supported in the mapped model")
+    }
+
+    override val associateCompilations: Set<CompilationDetails<*>> get() = emptySet()
+
+    override val compileDependencyFilesHolder: DependencyFilesHolder
+        get() = DependencyFilesHolder.ofVariantCompileDependencies(variant)
+
+    override val kotlinDependenciesHolder: HasKotlinDependencies
+        get() = variant
+
+    override val directlyIncludedKotlinSourceSets: MutableSet<KotlinSourceSet>
+        // FIXME: this effectively ignores the mutation of the set!
+        get() = compilation.defaultSourceSet.dependsOn.toMutableSet()
+}
+
+internal open class VariantMappedCompilationDetailsWithRuntime<T : KotlinCommonOptions>(
+    override val variant: KotlinGradleVariantWithRuntimeInternal,
+    target: KotlinTarget
+) : VariantMappedCompilationDetails<T>(variant, target),
+    CompilationDetailsWithRuntime<T> {
+    override val runtimeDependencyFilesHolder: DependencyFilesHolder
+        get() = DependencyFilesHolder.ofVariantRuntimeDependencies(variant)
+}
+
+internal class WithJavaCompilationDetails<T : KotlinCommonOptions>(
+    target: KotlinTarget,
+    compilationPurpose: String,
+    createKotlinOptions: DefaultCompilationDetails<*>.() -> T
+) : DefaultCompilationDetailsWithRuntime<T>(target, compilationPurpose, createKotlinOptions) {
+    override val compilation: KotlinWithJavaCompilation<T>
+        get() = super.compilation as KotlinWithJavaCompilation<T>
+
+    val javaSourceSet: SourceSet
+        get() = compilation.javaSourceSet
+
+    override val output: KotlinCompilationOutput by lazy { KotlinWithJavaCompilationOutput(compilation) }
+
+    override val compileDependencyFilesHolder: DependencyFilesHolder
+        get() = object : DependencyFilesHolder {
+            override val dependencyConfigurationName: String by javaSourceSet::compileClasspathConfigurationName
+            override var dependencyFiles: FileCollection by javaSourceSet::compileClasspath
+        }
+
+    override val runtimeDependencyFilesHolder: DependencyFilesHolder
+        get() = object : DependencyFilesHolder {
+            override val dependencyConfigurationName: String by javaSourceSet::runtimeClasspathConfigurationName
+            override var dependencyFiles: FileCollection by javaSourceSet::runtimeClasspath
+        }
+
+    override fun addAssociateCompilationDependencies(other: KotlinCompilation<*>) {
+        if (compilationPurpose != SourceSet.TEST_SOURCE_SET_NAME || other.name != SourceSet.MAIN_SOURCE_SET_NAME) {
+            super.addAssociateCompilationDependencies(other)
+        } // otherwise, do nothing: the Java Gradle plugin adds these dependencies for us, we don't need to add them to the classpath
+    }
+}
+
+internal class AndroidCompilationDetails(
+    target: KotlinTarget,
+    compilationPurpose: String,
+) : DefaultCompilationDetailsWithRuntime<KotlinJvmOptions>(
+    target,
+    compilationPurpose,
+    { KotlinJvmOptionsImpl() }
+) {
+    override val compilation: KotlinJvmAndroidCompilation
+        get() = super.compilation as KotlinJvmAndroidCompilation
+
+    val androidVariant = compilation.androidVariant
+
+    override val friendArtifacts: FileCollection
+        get() = target.project.files(super.friendArtifacts, compilation.testedVariantArtifacts)
+
+    override fun addAssociateCompilationDependencies(other: KotlinCompilation<*>) {
+        if ((other as? KotlinJvmAndroidCompilation)?.androidVariant != getTestedVariantData(androidVariant)) {
+            super.addAssociateCompilationDependencies(other)
+        } // otherwise, do nothing: the Android Gradle plugin adds these dependencies for us, we don't need to add them to the classpath
+    }
+
+    override val kotlinDependenciesHolder: HasKotlinDependencies
+        get() = object : HasKotlinDependencies by super.kotlinDependenciesHolder {
+            override val relatedConfigurationNames: List<String>
+                get() = super.relatedConfigurationNames + listOf(
+                    "${androidVariant.name}ApiElements",
+                    "${androidVariant.name}RuntimeElements",
+                    androidVariant.compileConfiguration.name,
+                    androidVariant.runtimeConfiguration.name
+                )
+        }
+}
+
+internal class MetadataCompilationDetails(target: KotlinTarget, name: String) :
+    DefaultCompilationDetails<KotlinMultiplatformCommonOptions>(
+        target,
+        name,
+        { KotlinMultiplatformCommonOptionsImpl() }
+    ) {
+
+    override val friendArtifacts: FileCollection
+        get() = super.friendArtifacts.plus(run {
+            val project = target.project
+            val friendSourceSets = getVisibleSourceSetsFromAssociateCompilations(target.project, defaultSourceSet)
+            project.files(friendSourceSets.mapNotNull { target.compilations.findByName(it.name)?.output?.classesDirs })
+        })
+}
+
+internal open class JsCompilationDetails(
+    target: KotlinTarget,
+    compilationPurpose: String,
+) : DefaultCompilationDetailsWithRuntime<KotlinJsOptions>(target, compilationPurpose, { KotlinJsOptionsImpl() }) {
+
+    protected open class JsCompilationDependenciesHolder(
+        val target: KotlinTarget,
+        val compilationPurpose: String,
+        val parent: HasKotlinDependencies
+    ) : HasKotlinDependencies by parent {
+        override val apiConfigurationName: String
+            get() = disambiguateNameInPlatform(API)
+
+        override val implementationConfigurationName: String
+            get() = disambiguateNameInPlatform(IMPLEMENTATION)
+
+        override val compileOnlyConfigurationName: String
+            get() = disambiguateNameInPlatform(COMPILE_ONLY)
+
+        override val runtimeOnlyConfigurationName: String
+            get() = disambiguateNameInPlatform(RUNTIME_ONLY)
+
+        protected open val disambiguationClassifierInPlatform: String?
+            get() = when (target) {
+                is KotlinJsTarget -> target.disambiguationClassifierInPlatform
+                is KotlinJsIrTarget -> target.disambiguationClassifierInPlatform
+                else -> error("Unexpected target type of $target")
+            }
+
+        private fun disambiguateNameInPlatform(simpleName: String): String {
+            return lowerCamelCaseName(
+                disambiguationClassifierInPlatform,
+                compilationPurpose.takeIf { it != KotlinCompilation.MAIN_COMPILATION_NAME },
+                simpleName
+            )
+        }
+    }
+
+    override val kotlinDependenciesHolder: HasKotlinDependencies
+        get() = JsCompilationDependenciesHolder(target, compilationPurpose, super.kotlinDependenciesHolder)
+
+    override val defaultSourceSetName: String
+        get() {
+            val classifier = if (target is KotlinJsTarget && target.irTarget != null)
+                target.disambiguationClassifierInPlatform
+            else target.disambiguationClassifier
+
+            return lowerCamelCaseName(
+                classifier,
+                compilationPurpose
+            )
+        }
+}
+
+internal class JsIrCompilationDetails(target: KotlinTarget, compilationPurpose: String) :
+    JsCompilationDetails(target, compilationPurpose) {
+
+    override fun addSourcesToCompileTask(sourceSet: KotlinSourceSet, addAsCommonSources: Lazy<Boolean>) {
+        super.addSourcesToCompileTask(sourceSet, addAsCommonSources)
+        (compilation as KotlinJsIrCompilation).allSources.add(sourceSet.kotlin)
+    }
+
+    override val defaultSourceSetName: String
+        get() {
+            val target = target as KotlinJsIrTarget
+            return lowerCamelCaseName(
+                if (target.mixedMode)
+                    target.disambiguationClassifierInPlatform
+                else
+                    target.disambiguationClassifier,
+                compilationPurpose
+            )
+        }
+
+    private class JsIrCompilationDependencyHolder(target: KotlinTarget, compilationPurpose: String, parent: HasKotlinDependencies) :
+        JsCompilationDependenciesHolder(target, compilationPurpose, parent) {
+        override val disambiguationClassifierInPlatform: String?
+            get() = (target as KotlinJsIrTarget).disambiguationClassifierInPlatform
+    }
+
+    override val kotlinDependenciesHolder: HasKotlinDependencies
+        get() = JsIrCompilationDependencyHolder(target, compilationPurpose, super.kotlinDependenciesHolder)
+}
+
+internal class KotlinDependencyConfigurationsHolder(
+    val project: Project,
+    private val configurationNamesPrefix: String?,
+) : HasKotlinDependencies {
+
+    override val apiConfigurationName: String
+        get() = lowerCamelCaseName(configurationNamesPrefix, API)
+
+    override val implementationConfigurationName: String
+        get() = lowerCamelCaseName(configurationNamesPrefix, IMPLEMENTATION)
+
+    override val compileOnlyConfigurationName: String
+        get() = lowerCamelCaseName(configurationNamesPrefix, COMPILE_ONLY)
+
+    override val runtimeOnlyConfigurationName: String
+        get() = lowerCamelCaseName(configurationNamesPrefix, RUNTIME_ONLY)
+
+    override fun dependencies(configure: KotlinDependencyHandler.() -> Unit): Unit =
+        DefaultKotlinDependencyHandler(this, project).run(configure)
+
+    override fun dependencies(configureClosure: Closure<Any?>) =
+        dependencies f@{ project.configure(this@f, configureClosure) }
+}

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/KotlinCommonCompilation.kt

@@ -21,9 +21,9 @@ interface KotlinMetadataCompilation<T : KotlinCommonOptions> : KotlinCompilation
 class KotlinCommonCompilation(
     target: KotlinTarget,
     name: String
-) : AbstractKotlinCompilation<KotlinMultiplatformCommonOptions>(target, name), KotlinMetadataCompilation<KotlinMultiplatformCommonOptions> {
-
-    override val kotlinOptions: KotlinMultiplatformCommonOptions = KotlinMultiplatformCommonOptionsImpl()
+) : AbstractKotlinCompilation<KotlinMultiplatformCommonOptions>(
+    MetadataCompilationDetails(target, name)
+), KotlinMetadataCompilation<KotlinMultiplatformCommonOptions> {
 
     override val compileKotlinTask: KotlinCompileCommon
         get() = super.compileKotlinTask as KotlinCompileCommon
@@ -32,11 +32,4 @@ class KotlinCommonCompilation(
         get() = target.project.isKotlinGranularMetadataEnabled && !forceCompilationToKotlinMetadata
 
     internal var forceCompilationToKotlinMetadata: Boolean = false
-
-    override val friendArtifacts: FileCollection
-        get() = super.friendArtifacts.plus(run {
-            val project = target.project
-            val friendSourceSets = getVisibleSourceSetsFromAssociateCompilations(target.project, defaultSourceSet)
-            project.files(friendSourceSets.mapNotNull { target.compilations.findByName(it.name)?.output?.classesDirs })
-        })
 }

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/internal/KotlinCompilationsModuleGroups.kt

@@ -9,6 +9,8 @@ import org.gradle.api.Project
 import org.gradle.api.plugins.ExtraPropertiesExtension
 import org.jetbrains.kotlin.gradle.plugin.KotlinCompilation
 import org.jetbrains.kotlin.gradle.plugin.mpp.isMain
+import org.jetbrains.kotlin.gradle.plugin.mpp.pm20.KotlinCompilationData
+import org.jetbrains.kotlin.gradle.plugin.mpp.pm20.isMainCompilationData
 
 /** This is a disjoint-set union-like approach to having a module name that is equal across associated compilations, as the compiler
  * now requires that to properly compile internal calls to friend classes. Associating a compilation with another one leads to their
@@ -17,10 +19,10 @@ import org.jetbrains.kotlin.gradle.plugin.mpp.isMain
  * TODO: once the compiler is able to correctly generate calls to internals in other modules, remove this logic.
  */
 internal class KotlinCompilationsModuleGroups {
-    private val moduleLeaderCompilationMap: MutableMap<KotlinCompilation<*>, KotlinCompilation<*>> =
+    private val moduleLeaderCompilationMap: MutableMap<KotlinCompilationData<*>, KotlinCompilationData<*>> =
         mutableMapOf()
 
-    fun getModuleLeader(compilation: KotlinCompilation<*>): KotlinCompilation<*> {
+    fun getModuleLeader(compilation: KotlinCompilationData<*>): KotlinCompilationData<*> {
         if (compilation !in moduleLeaderCompilationMap) {
             moduleLeaderCompilationMap[compilation] = compilation
         }
@@ -31,7 +33,7 @@ internal class KotlinCompilationsModuleGroups {
         }
     }
 
-    fun unionModules(compilationA: KotlinCompilation<*>, compilationB: KotlinCompilation<*>) {
+    fun unionModules(compilationA: KotlinCompilationData<*>, compilationB: KotlinCompilationData<*>) {
         val aLeader = getModuleLeader(compilationA)
         val bLeader = getModuleLeader(compilationB)
 
@@ -41,10 +43,10 @@ internal class KotlinCompilationsModuleGroups {
         listOf(aLeader, bLeader).run {
             /** heuristically choose the new leader: choose `main` when possible, don't choose `*test*` when there's an alternative,
              * if that didn't work, choose the first name lexicographically */
-            val newLeader = singleOrNull { it.isMain() }
-                ?: singleOrNull { it.name.contains("main", true) }
-                ?: singleOrNull { !it.name.contains("test", true) }
-                ?: minByOrNull { it.name }!!
+            val newLeader = singleOrNull { it.isMainCompilationData() }
+                ?: singleOrNull { it.compilationPurpose.contains("main", true) }
+                ?: singleOrNull { !it.compilationPurpose.contains("test", true) }
+                ?: minByOrNull { it.compilationPurpose }!!
 
             forEach { moduleLeaderCompilationMap[it] = newLeader }
         }
@@ -53,11 +55,11 @@ internal class KotlinCompilationsModuleGroups {
     companion object {
         private const val EXT_NAME = "kotlin.compilations.moduleGroups"
 
-        fun getModuleLeaderCompilation(compilation: KotlinCompilation<*>): KotlinCompilation<*> =
-            getInstance(compilation.target.project).getModuleLeader(compilation)
+        fun getModuleLeaderCompilation(compilation: KotlinCompilationData<*>): KotlinCompilationData<*> =
+            getInstance(compilation.project).getModuleLeader(compilation)
 
-        fun unionModules(compilationA: KotlinCompilation<*>, compilationB: KotlinCompilation<*>) {
-            getInstance(compilationA.target.project).unionModules(compilationA, compilationB)
+        fun unionModules(compilationA: KotlinCompilationData<*>, compilationB: KotlinCompilationData<*>) {
+            getInstance(compilationA.project).unionModules(compilationA, compilationB)
         }
 
         private fun getInstance(project: Project): KotlinCompilationsModuleGroups {

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/kotlinCompilations.kt

@@ -9,25 +9,16 @@ import groovy.lang.Closure
 import org.gradle.api.GradleException
 import org.gradle.api.Project
 import org.gradle.api.Task
-import org.gradle.api.UnknownTaskException
-import org.gradle.api.artifacts.Dependency
 import org.gradle.api.attributes.AttributeContainer
 import org.gradle.api.execution.TaskExecutionListener
 import org.gradle.api.file.FileCollection
-import org.gradle.api.file.SourceDirectorySet
-import org.gradle.api.plugins.BasePluginExtension
 import org.gradle.api.plugins.ExtraPropertiesExtension
 import org.gradle.api.provider.Property
 import org.gradle.api.tasks.TaskProvider
 import org.gradle.api.tasks.TaskState
-import org.gradle.api.tasks.bundling.AbstractArchiveTask
-import org.gradle.util.ConfigureUtil
 import org.jetbrains.kotlin.gradle.dsl.*
 import org.jetbrains.kotlin.gradle.plugin.*
-import org.jetbrains.kotlin.gradle.plugin.mpp.internal.KotlinCompilationsModuleGroups
-import org.jetbrains.kotlin.gradle.plugin.mpp.pm20.KotlinCompilationData
-import org.jetbrains.kotlin.gradle.plugin.sources.defaultSourceSetLanguageSettingsChecker
-import org.jetbrains.kotlin.gradle.plugin.sources.withAllDependsOnSourceSets
+import org.jetbrains.kotlin.gradle.plugin.mpp.pm20.*
 import org.jetbrains.kotlin.gradle.plugin.sources.resolveAllDependsOnSourceSets
 import org.jetbrains.kotlin.gradle.tasks.AbstractKotlinCompile
 import org.jetbrains.kotlin.gradle.tasks.locateTask
@@ -54,12 +45,29 @@ internal fun KotlinCompilation<*>.isMain(): Boolean =
 internal val KotlinCompilation<*>.kotlinSourceSetsIncludingDefault: Set<KotlinSourceSet> get() = kotlinSourceSets + defaultSourceSet
 
 abstract class AbstractKotlinCompilation<T : KotlinCommonOptions>(
-    target: KotlinTarget,
-    override val compilationPurpose: String
-) : KotlinCompilation<T>, HasKotlinDependencies, KotlinCompilationData<T> {
+    internal open val compilationDetails: CompilationDetails<T>
+) : KotlinCompilation<T>,
+    // FIXME: replace with separate `final override`s, which is safer wrt accidental overrides
+    HasKotlinDependencies by compilationDetails.kotlinDependenciesHolder,
+    KotlinCompilationData<T> by compilationDetails.compilationData {
 
-    override val compilationName: String
-        get() = compilationPurpose
+    override val target: KotlinTarget get() = compilationDetails.target
+
+    final override val compileDependencyConfigurationName: String
+        get() = compilationDetails.compileDependencyFilesHolder.dependencyConfigurationName
+
+    // FIXME: use delegation to callable reference once KT-50019 is fixed
+    final override var compileDependencyFiles: FileCollection
+        get() = compilationDetails.compileDependencyFilesHolder.dependencyFiles
+        set(value) {
+            compilationDetails.compileDependencyFilesHolder.dependencyFiles = value
+        }
+
+    override val platformType: KotlinPlatformType get() = compilationDetails.compilationData.platformType
+    final override val kotlinSourceSets: MutableSet<KotlinSourceSet> get() = compilationDetails.directlyIncludedKotlinSourceSets
+    final override val defaultSourceSetName: String get() = compilationDetails.defaultSourceSetName
+
+    final override val compilationName: String get() = compilationDetails.compilationData.compilationPurpose
 
     override fun kotlinOptions(configure: T.() -> Unit) =
         configure(kotlinOptions)
@@ -72,242 +80,27 @@ abstract class AbstractKotlinCompilation<T : KotlinCommonOptions>(
     override val compileKotlinTaskProvider: TaskProvider<out KotlinCompile<T>>
         get() = target.project.locateTask(compileKotlinTaskName) ?: throw GradleException("Couldn't locate  task $compileKotlinTaskName")
 
-    // Don't declare this property in the constructor to avoid NPE
-    // when an overriding property of a subclass is accessed instead.
-    @Suppress("CanBePrimaryConstructorProperty")
-    override val target: KotlinTarget = target
-
-    private val attributeContainer = HierarchyAttributeContainer(target.attributes)
+    private val attributeContainer by lazy { HierarchyAttributeContainer(target.attributes) }
 
     override fun getAttributes(): AttributeContainer = attributeContainer
 
-    override val kotlinSourceSets: MutableSet<KotlinSourceSet> = mutableSetOf()
-
-    override val allKotlinSourceSets: Set<KotlinSourceSet>
-        get() = kotlinSourceSets + kotlinSourceSets.resolveAllDependsOnSourceSets()
-
-    override val defaultSourceSetName: String
-        get() = lowerCamelCaseName(
-            target.disambiguationClassifier.takeIf { target !is KotlinMetadataTarget },
-            when {
-                isMain() && target is KotlinMetadataTarget ->
-                    KotlinSourceSet.COMMON_MAIN_SOURCE_SET_NAME // corner case: main compilation of the metadata target compiles commonMain
-                else -> compilationPurpose
-            }
-        )
-
     override val defaultSourceSet: KotlinSourceSet
         get() = target.project.kotlinExtension.sourceSets.getByName(defaultSourceSetName)
 
     override fun defaultSourceSet(configure: KotlinSourceSet.() -> Unit) = defaultSourceSet.configure()
 
-    override val output: KotlinCompilationOutput by lazy {
-        DefaultKotlinCompilationOutput(
-            target.project,
-            Callable { target.project.buildDir.resolve("processedResources/${target.targetName}/$name") })
-    }
-
-    open fun addSourcesToCompileTask(sourceSet: KotlinSourceSet, addAsCommonSources: Lazy<Boolean>) =
-        addSourcesToKotlinCompileTask(
-            project,
-            compileKotlinTaskName,
-            sourceSet.customSourceFilesExtensions,
-            addAsCommonSources
-        ) { sourceSet.kotlin }
-
-    internal fun addExactSourceSetsEagerly(sourceSets: Set<KotlinSourceSet>) {
-        with(target.project) {
-            //TODO possibly issue with forced instantiation
-            sourceSets.forEach { sourceSet ->
-                addSourcesToCompileTask(
-                    sourceSet,
-                    addAsCommonSources = lazy {
-                        CompilationSourceSetUtil.sourceSetsInMultipleCompilations(project).contains(sourceSet.name)
-                    }
-                )
-
-                // Use `forced = false` since `api`, `implementation`, and `compileOnly` may be missing in some cases like
-                // old Java & Android projects:
-                addExtendsFromRelation(apiConfigurationName, sourceSet.apiConfigurationName, forced = false)
-                addExtendsFromRelation(implementationConfigurationName, sourceSet.implementationConfigurationName, forced = false)
-                addExtendsFromRelation(compileOnlyConfigurationName, sourceSet.compileOnlyConfigurationName, forced = false)
-
-                if (this@AbstractKotlinCompilation is KotlinCompilationToRunnableFiles<*>) {
-                    addExtendsFromRelation(runtimeOnlyConfigurationName, sourceSet.runtimeOnlyConfigurationName, forced = false)
-                }
-
-                if (sourceSet.name != defaultSourceSetName) {
-                    kotlinExtension.sourceSets.findByName(defaultSourceSetName)?.let { defaultSourceSet ->
-                        // Temporary solution for checking consistency across source sets participating in a compilation that may
-                        // not be interconnected with the dependsOn relation: check the settings as if the default source set of
-                        // the compilation depends on the one added to the compilation:
-                        defaultSourceSetLanguageSettingsChecker.runAllChecks(
-                            defaultSourceSet,
-                            sourceSet
-                        )
-                    }
-                }
-            }
-        }
-    }
-
     override fun source(sourceSet: KotlinSourceSet) {
-        if (kotlinSourceSets.add(sourceSet)) {
-            target.project.whenEvaluated {
-                addExactSourceSetsEagerly(sourceSet.withAllDependsOnSourceSets())
-            }
-        }
+        compilationDetails.source(sourceSet)
     }
 
-    override val compileDependencyConfigurationName: String
-        get() = lowerCamelCaseName(
-            target.disambiguationClassifier,
-            compilationPurpose.takeIf { it != KotlinCompilation.MAIN_COMPILATION_NAME }.orEmpty(),
-            "compileClasspath"
-        )
-
-    override val compileKotlinTaskName: String
-        get() = lowerCamelCaseName(
-            "compile",
-            compilationPurpose.takeIf { it != KotlinCompilation.MAIN_COMPILATION_NAME },
-            "Kotlin",
-            target.targetName
-        )
-
-    override val compileAllTaskName: String
-        get() = lowerCamelCaseName(target.disambiguationClassifier, compilationPurpose, "classes")
-
-    override lateinit var compileDependencyFiles: FileCollection
-
-    override val apiConfigurationName: String
-        get() = disambiguateName(API)
-
-    override val implementationConfigurationName: String
-        get() = disambiguateName(IMPLEMENTATION)
-
-    override val compileOnlyConfigurationName: String
-        get() = disambiguateName(COMPILE_ONLY)
-
-    override val runtimeOnlyConfigurationName: String
-        get() = disambiguateName(RUNTIME_ONLY)
-
-    override fun dependencies(configure: KotlinDependencyHandler.() -> Unit): Unit =
-        DefaultKotlinDependencyHandler(this, target.project).run(configure)
-
-    override fun dependencies(configureClosure: Closure<Any?>) =
-        dependencies f@{ ConfigureUtil.configure(configureClosure, this@f) }
-
     override fun toString(): String = "compilation '$compilationPurpose' ($target)"
 
-    internal val friendArtifactsTask: TaskProvider<AbstractArchiveTask>? by lazy {
-        if (associateWithTransitiveClosure.any { it.isMain() }) {
-            val archiveTasks = target.project.tasks.withType(AbstractArchiveTask::class.java)
-            if (!archiveTasks.isEmpty()) {
-                try {
-                    archiveTasks.named(target.artifactsTaskName)
-                } catch (e: UnknownTaskException) {
-                    // Native tasks does not extend AbstractArchiveTask
-                    null
-                }
-            } else {
-                null
-            }
-        } else {
-            null
-        }
-    }
-
-    /**
-     * If a compilation is aware of its associate compilations' outputs being added to the classpath in a transformed or packaged way,
-     * it should point to those friend artifact files via this property.
-     */
-    internal open val friendArtifacts: FileCollection
-        get() = with(target.project) {
-            val friendArtifactsTaskProvider = friendArtifactsTask
-            if (friendArtifactsTaskProvider != null) {
-                // In case the main artifact is transitively added to the test classpath via a test dependency on another module
-                // that depends on this module's production part, include the main artifact in the friend artifacts, lazily:
-                files(
-                    Callable {
-                        friendArtifactsTaskProvider.flatMap { it.archiveFile }
-                    }
-                )
-            } else files()
-        }
-
-    override val friendPaths: Iterable<FileCollection>
-        get() = mutableListOf<FileCollection>().also { allCollections ->
-            associateWithTransitiveClosure.forEach { allCollections.add(it.output.classesDirs) }
-            allCollections.add(friendArtifacts)
-        }
-
-    override val moduleName: String
-        get() = KotlinCompilationsModuleGroups.getModuleLeaderCompilation(this).takeIf { it != this }?.ownModuleName() ?: ownModuleName
-
     override fun associateWith(other: KotlinCompilation<*>) {
-        require(other.target == target) { "Only associations between compilations of a single target are supported" }
-        other as AbstractKotlinCompilation<*>
-
-        _associateWith += other
-
-        addAssociateCompilationDependencies(other)
-        KotlinCompilationsModuleGroups.unionModules(this, other)
+        compilationDetails.associateWith((other as AbstractKotlinCompilation<*>).compilationDetails)
     }
 
-    /**
-     * Adds `allDependencies` of configurations mentioned in `configurationNames` to configuration named [this] in
-     * a lazy manner
-     */
-    private fun String.addAllDependenciesFromOtherConfigurations(project: Project, vararg configurationNames: String) {
-        project.configurations.named(this).configure { receiverConfiguration ->
-            receiverConfiguration.dependencies.addAllLater(
-                project.objects.listProperty(Dependency::class.java).apply {
-                    set(
-                        project.provider {
-                            configurationNames
-                                .map { project.configurations.getByName(it) }
-                                .flatMap { it.allDependencies }
-                        }
-                    )
-                }
-            )
-        }
-    }
-
-    @OptIn(ExperimentalStdlibApi::class)
-    protected open fun addAssociateCompilationDependencies(other: KotlinCompilation<*>) {
-        /*
-          we add dependencies to compileDependencyConfiguration ('compileClasspath' usually) and runtimeDependency
-          ('runtimeClasspath') instead of modifying respective api/implementation/compileOnly/runtimeOnly configs
-
-          This is needed because api/implementation/compileOnly/runtimeOnly are used in IDE Import and will leak
-          to dependencies of IDE modules. But they are not needed here, because IDE resolution works inherently
-          transitively and symbols from associated compilation will be resolved from source sets of associated
-          compilation itself (moreover, direct dependencies are not equivalent to transitive ones because of
-          resolution order - e.g. in case of FQNs clash, so it's even harmful)
-        */
-        project.dependencies.add(compileOnlyConfigurationName, project.files(Callable { other.output.classesDirs }))
-        project.dependencies.add(runtimeOnlyConfigurationName, project.files(Callable { other.output.allOutputs }))
-
-        compileDependencyConfigurationName.addAllDependenciesFromOtherConfigurations(
-            project,
-            other.apiConfigurationName,
-            other.implementationConfigurationName,
-            other.compileOnlyConfigurationName
-        )
-
-        runtimeDependencyConfigurationName?.addAllDependenciesFromOtherConfigurations(
-            project,
-            other.apiConfigurationName,
-            other.implementationConfigurationName,
-            other.runtimeOnlyConfigurationName
-        )
-    }
-
-    private val _associateWith: MutableSet<AbstractKotlinCompilation<*>> = mutableSetOf()
-
     override val associateWith: List<KotlinCompilation<*>>
-        get() = Collections.unmodifiableList(_associateWith.toList())
+        get() = Collections.unmodifiableList(compilationDetails.associateCompilations.map { it.compilation })
 
     override val project: Project
         get() = target.project
@@ -315,20 +108,12 @@ abstract class AbstractKotlinCompilation<T : KotlinCommonOptions>(
     override val owner: KotlinTarget
         get() = target
 
-    override val compilationClassifier: String?
-        get() = target.disambiguationClassifier
+    override val allKotlinSourceSets: Set<KotlinSourceSet>
+        get() = compilationDetails.directlyIncludedKotlinSourceSets +
+                compilationDetails.directlyIncludedKotlinSourceSets.resolveAllDependsOnSourceSets()
 
-    override val kotlinSourceDirectoriesByFragmentName: Map<String, SourceDirectorySet>
-        get() = defaultSourceSet.withAllDependsOnSourceSets().associate { it.name to it.kotlin }
-
-    override val languageSettings: LanguageSettingsBuilder
-        get() = defaultSourceSet.languageSettings
-
-    override val platformType: KotlinPlatformType
-        get() = target.platformType
-
-    override val ownModuleName: String
-        get() = ownModuleName()
+    override val relatedConfigurationNames: List<String>
+        get() = compilationDetails.kotlinDependenciesHolder.relatedConfigurationNames + compileDependencyConfigurationName
 }
 
 internal fun addCommonSourcesToKotlinCompileTask(
@@ -368,14 +153,6 @@ internal fun addSourcesToKotlinCompileTask(
         }
 }
 
-private fun KotlinCompilation<*>.ownModuleName(): String {
-    val project = target.project
-    val baseName = project.extensions.getByType(BasePluginExtension::class.java).archivesName.orNull
-        ?: project.name
-    val suffix = if (isMain()) "" else "_$compilationName"
-    return filterModuleName("$baseName$suffix")
-}
-
 internal val KotlinCompilation<*>.associateWithTransitiveClosure: Iterable<KotlinCompilation<*>>
     get() = mutableSetOf<KotlinCompilation<*>>().apply {
         fun visit(other: KotlinCompilation<*>) {
@@ -387,17 +164,19 @@ internal val KotlinCompilation<*>.associateWithTransitiveClosure: Iterable<Kotli
     }
 
 abstract class AbstractKotlinCompilationToRunnableFiles<T : KotlinCommonOptions>(
-    target: KotlinTarget,
-    name: String
-) : AbstractKotlinCompilation<T>(target, name), KotlinCompilationToRunnableFiles<T> {
-    override val runtimeDependencyConfigurationName: String
-        get() = lowerCamelCaseName(
-            target.disambiguationClassifier,
-            compilationPurpose.takeIf { it != KotlinCompilation.MAIN_COMPILATION_NAME },
-            "runtimeClasspath"
-        )
+    override val compilationDetails: CompilationDetailsWithRuntime<T>,
+) : AbstractKotlinCompilation<T>(compilationDetails),
+    KotlinCompilationToRunnableFiles<T> {
 
-    override lateinit var runtimeDependencyFiles: FileCollection
+    final override val runtimeDependencyConfigurationName: String get() = compilationDetails.runtimeDependencyFilesHolder.dependencyConfigurationName
+    final override var runtimeDependencyFiles: FileCollection
+        get() = compilationDetails.runtimeDependencyFilesHolder.dependencyFiles
+        set(value) {
+            compilationDetails.runtimeDependencyFilesHolder.dependencyFiles = value
+        }
+
+    override val relatedConfigurationNames: List<String>
+        get() = super<AbstractKotlinCompilation>.relatedConfigurationNames + runtimeDependencyConfigurationName
 }
 
 internal fun KotlinCompilation<*>.disambiguateName(simpleName: String): String {
@@ -485,4 +264,4 @@ internal object CompilationSourceSetUtil {
 private val invalidModuleNameCharactersRegex = """[\\/\r\n\t]""".toRegex()
 
 internal fun filterModuleName(moduleName: String): String =
-    moduleName.replace(invalidModuleNameCharactersRegex, "_")
+    moduleName.replace(invalidModuleNameCharactersRegex, "_")

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/pm20/KotlinGradleFragment.kt

@@ -11,9 +11,11 @@ import org.gradle.api.Project
 import org.gradle.api.file.SourceDirectorySet
 import org.gradle.api.provider.Provider
 import org.gradle.util.ConfigureUtil
+import org.jetbrains.kotlin.gradle.plugin.HasKotlinDependencies
 import org.jetbrains.kotlin.gradle.plugin.KotlinDependencyHandler
 import org.jetbrains.kotlin.gradle.plugin.LanguageSettingsBuilder
 import org.jetbrains.kotlin.gradle.plugin.mpp.DefaultKotlinDependencyHandler
+import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinDependencyConfigurationsHolder
 import org.jetbrains.kotlin.gradle.plugin.mpp.toModuleDependency
 import org.jetbrains.kotlin.gradle.plugin.sources.DefaultLanguageSettingsBuilder
 import org.jetbrains.kotlin.gradle.plugin.sources.FragmentConsistencyChecker

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/pm20/KotlinJvmVariant.kt

@@ -8,7 +8,6 @@ package org.jetbrains.kotlin.gradle.plugin.mpp.pm20
 import groovy.lang.Closure
 import org.gradle.api.artifacts.Configuration
 import org.gradle.api.plugins.BasePluginConvention
-import org.gradle.api.GradleException
 import org.gradle.api.Project
 import org.gradle.api.attributes.AttributeContainer
 import org.gradle.api.file.FileCollection
@@ -25,7 +24,6 @@ import org.jetbrains.kotlin.gradle.plugin.mpp.pm20.util.unambiguousNameInProject
 import org.jetbrains.kotlin.gradle.plugin.sources.kpm.FragmentMappedKotlinSourceSet
 import org.jetbrains.kotlin.gradle.targets.jvm.KotlinJvmTarget
 import org.jetbrains.kotlin.gradle.targets.jvm.KotlinJvmTargetConfigurator
-import org.jetbrains.kotlin.gradle.tasks.*
 import org.jetbrains.kotlin.gradle.tasks.locateTask
 import org.jetbrains.kotlin.project.model.refinesClosure
 import java.util.concurrent.Callable
@@ -68,109 +66,16 @@ internal fun KotlinGradleVariant.ownModuleName(): String {
     return filterModuleName("$baseName$suffix")
 }
 
-open class KotlinVariantMappedJvmCompilation(
-    override val target: KotlinJvmTarget,
-    internal val variant: KotlinJvmVariant,
-) : KotlinJvmCompilation(target, variant.containingModule.name) {
-    // TODO: in the legacy model, it used to be a KotlinCompilationWithResources
-
-    override val runtimeDependencyConfigurationName: String
-        get() = variant.runtimeDependenciesConfiguration.name
-
-    override var runtimeDependencyFiles: FileCollection
-        get() = variant.runtimeDependencyFiles
-        set(value) {
-            variant.runtimeDependencyFiles = value
-        }
-
-    // TODO: compilation data implements compileDependencyFiles as a val, not var, fix this?
-    override val compileDependencyConfigurationName: String
-        get() = variant.compileDependenciesConfiguration.name
-
-    override var compileDependencyFiles: FileCollection
-        get() = compilationData.compileDependencyFiles
-        set(value) {
-            variant.compileDependencyFiles = value
-        }
-
-    private val compilationData: KotlinJvmVariantCompilationData
-        get() = variant.compilationData
-
-    override val kotlinOptions: KotlinJvmOptions = compilationData.kotlinOptions
-
-    override val compilationName: String
-        get() = compilationData.compilationPurpose
-
-    // FIXME: mutating this set should not be allowed
-    override val kotlinSourceSets: MutableSet<KotlinSourceSet>
-        get() = super.kotlinSourceSets
-
-    override val allKotlinSourceSets: Set<KotlinSourceSet>
-        get() {
-            val allMappedSourceSets = target.project.kotlinExtension.sourceSets
-                .filterIsInstance<FragmentMappedKotlinSourceSet>()
-                .associateBy { it.underlyingFragment }
-            return variant.refinesClosure.mapNotNull { allMappedSourceSets[it] }.toSet()
-        }
-
-    override val defaultSourceSetName: String
-        get() = variant.unambiguousNameInProject
-
-    override fun source(sourceSet: KotlinSourceSet) {
-        defaultSourceSet.dependsOn(sourceSet)
-    }
-
-    override fun associateWith(other: KotlinCompilation<*>) {
-        throw UnsupportedOperationException("not supported in the mapped model")
-    }
-
-    override val associateWith: List<KotlinCompilation<*>> get() = emptyList()
-
-    override fun getAttributes(): AttributeContainer {
-        // TODO: not implemented?
-        return HierarchyAttributeContainer(target.attributes)
-    }
-
-    override fun dependencies(configure: KotlinDependencyHandler.() -> Unit) {
-        variant.dependencies(configure)
-    }
-
-    override fun dependencies(configureClosure: Closure<Any?>) {
-        variant.dependencies(configureClosure)
-    }
-
-    override val apiConfigurationName: String
-        get() = variant.apiConfigurationName
-    override val implementationConfigurationName: String
-        get() = variant.implementationConfigurationName
-    override val compileOnlyConfigurationName: String
-        get() = variant.compileOnlyConfigurationName
-    override val runtimeOnlyConfigurationName: String
-        get() = variant.runtimeOnlyConfigurationName
-
-    override val project: Project
-        get() = variant.project
-
-    override val output: KotlinCompilationOutput
-        get() = variant.compilationOutputs
-
-    override val compileKotlinTaskName: String
-        get() = compilationData.compileKotlinTaskName
-
-    override val compileAllTaskName: String
-        get() = compilationData.compileAllTaskName
-
-    override val moduleName: String
-        get() = compilationData.moduleName
-}
-
 class KotlinMappedJvmCompilationFactory(
     target: KotlinJvmTarget
 ) : KotlinJvmCompilationFactory(target) {
-    override fun create(name: String): KotlinVariantMappedJvmCompilation {
+    override fun create(name: String): KotlinJvmCompilation {
         val module = target.project.kpmModules.maybeCreate(name)
         val variant = module.fragments.create(target.name, KotlinJvmVariant::class.java)
-        return KotlinVariantMappedJvmCompilation(target, variant)
+
+        return KotlinJvmCompilation(
+            VariantMappedCompilationDetailsWithRuntime(variant, target),
+        )
     }
 }
 
@@ -196,7 +101,10 @@ class KotlinMappedJvmTargetConfigurator : KotlinJvmTargetConfigurator() {
     override fun createArchiveTasks(target: KotlinJvmTarget): TaskProvider<out Zip> =
         checkNotNull(
             target.project.locateTask<Jar>(
-                (target.compilations.getByName(KotlinCompilation.MAIN_COMPILATION_NAME) as KotlinVariantMappedJvmCompilation).variant.outputsJarTaskName
+                target.compilations.getByName(KotlinCompilation.MAIN_COMPILATION_NAME)
+                    .compilationDetails.let { it as VariantMappedCompilationDetails<*> }
+                    .variant.let { it as KotlinJvmVariant }
+                    .outputsJarTaskName
             )
         )
-}
+}

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/pm20/util/DependencyFilesHolder.kt

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2010-2021 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.pm20.util
+
+import org.gradle.api.Project
+import org.gradle.api.file.FileCollection
+import org.jetbrains.kotlin.gradle.plugin.mpp.pm20.KotlinGradleVariant
+import org.jetbrains.kotlin.gradle.plugin.mpp.pm20.KotlinGradleVariantWithRuntime
+
+interface DependencyFilesHolder {
+    val dependencyConfigurationName: String
+    var dependencyFiles: FileCollection
+
+    companion object
+}
+
+internal fun DependencyFilesHolder.Companion.ofVariantCompileDependencies(variant: KotlinGradleVariant): DependencyFilesHolder =
+    object : DependencyFilesHolder {
+        override val dependencyConfigurationName: String
+            get() = variant.compileDependenciesConfiguration.name
+        override var dependencyFiles: FileCollection
+            get() = variant.compileDependencyFiles
+            set(value) { variant.compileDependencyFiles = value }
+    }
+
+internal fun DependencyFilesHolder.Companion.ofVariantRuntimeDependencies(variant: KotlinGradleVariantWithRuntime): DependencyFilesHolder =
+    object : DependencyFilesHolder {
+        override val dependencyConfigurationName: String
+            get() = variant.runtimeDependenciesConfiguration.name
+        override var dependencyFiles: FileCollection
+            get() = variant.runtimeDependencyFiles
+            set(value) { variant.runtimeDependencyFiles = value }
+    }
+
+class SimpleDependencyFilesHolder(
+    override val dependencyConfigurationName: String,
+    override var dependencyFiles: FileCollection
+) : DependencyFilesHolder
+
+internal fun Project.newDependencyFilesHolder(dependencyConfigurationName: String): DependencyFilesHolder =
+    SimpleDependencyFilesHolder(dependencyConfigurationName, project.files())

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/KotlinJsCompilation.kt

@@ -13,24 +13,24 @@ import org.gradle.api.tasks.TaskProvider
 import org.gradle.util.ConfigureUtil
 import org.gradle.util.WrapUtil
 import org.jetbrains.kotlin.gradle.dsl.KotlinJsOptions
-import org.jetbrains.kotlin.gradle.dsl.KotlinJsOptionsImpl
-import org.jetbrains.kotlin.gradle.plugin.KotlinCompilation
 import org.jetbrains.kotlin.gradle.plugin.KotlinCompilationWithResources
 import org.jetbrains.kotlin.gradle.plugin.KotlinTarget
 import org.jetbrains.kotlin.gradle.plugin.PropertiesProvider
-import org.jetbrains.kotlin.gradle.targets.js.KotlinJsTarget
 import org.jetbrains.kotlin.gradle.targets.js.dsl.KotlinJsSubTargetContainerDsl
 import org.jetbrains.kotlin.gradle.targets.js.dukat.ExternalsOutputFormat
 import org.jetbrains.kotlin.gradle.targets.js.ir.JsBinary
 import org.jetbrains.kotlin.gradle.targets.js.ir.KotlinJsBinaryContainer
 import org.jetbrains.kotlin.gradle.targets.js.npm.PackageJson
 import org.jetbrains.kotlin.gradle.tasks.Kotlin2JsCompile
-import org.jetbrains.kotlin.gradle.utils.*
 
-open class KotlinJsCompilation(
-    target: KotlinTarget,
-    name: String
-) : AbstractKotlinCompilationToRunnableFiles<KotlinJsOptions>(target, name), KotlinCompilationWithResources<KotlinJsOptions> {
+open class KotlinJsCompilation internal constructor(
+    compilationDetails: JsCompilationDetails
+) : AbstractKotlinCompilationToRunnableFiles<KotlinJsOptions>(compilationDetails),
+    KotlinCompilationWithResources<KotlinJsOptions> {
+
+    final override val target: KotlinTarget get() = super.target
+
+    constructor(target: KotlinTarget, name: String) : this(JsCompilationDetails(target, name))
 
     private val kotlinProperties = PropertiesProvider(target.project)
 
@@ -39,8 +39,6 @@ open class KotlinJsCompilation(
 
     internal open val defaultExternalsOutputFormat: ExternalsOutputFormat = ExternalsOutputFormat.SOURCE
 
-    override val kotlinOptions: KotlinJsOptions = KotlinJsOptionsImpl()
-
     internal val binaries: KotlinJsBinaryContainer =
         target.project.objects.newInstance(
             KotlinJsBinaryContainer::class.java,
@@ -77,41 +75,7 @@ open class KotlinJsCompilation(
 
     fun packageJson(handler: Closure<*>) {
         packageJson {
-            ConfigureUtil.configure(handler, this)
+            project.configure(this, handler)
         }
     }
-
-    override val apiConfigurationName: String
-        get() = disambiguateNameInPlatform(API)
-
-    override val implementationConfigurationName: String
-        get() = disambiguateNameInPlatform(IMPLEMENTATION)
-
-    override val compileOnlyConfigurationName: String
-        get() = disambiguateNameInPlatform(COMPILE_ONLY)
-
-    override val runtimeOnlyConfigurationName: String
-        get() = disambiguateNameInPlatform(RUNTIME_ONLY)
-
-    protected open val disambiguationClassifierInPlatform: String?
-        get() = (target as KotlinJsTarget).disambiguationClassifierInPlatform
-
-    private fun disambiguateNameInPlatform(simpleName: String): String {
-        return lowerCamelCaseName(
-            disambiguationClassifierInPlatform,
-            compilationPurpose.takeIf { it != KotlinCompilation.MAIN_COMPILATION_NAME },
-            simpleName
-        )
-    }
-
-    override val defaultSourceSetName: String
-        get() {
-            val target = target as KotlinJsTarget
-            return lowerCamelCaseName(
-                target.irTarget?.let {
-                    target.disambiguationClassifierInPlatform
-                } ?: target.disambiguationClassifier,
-                compilationPurpose
-            )
-        }
 }

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/ir/KotlinJsIrCompilation.kt

@@ -6,38 +6,17 @@
 package org.jetbrains.kotlin.gradle.targets.js.ir
 
 import org.gradle.api.file.SourceDirectorySet
-import org.jetbrains.kotlin.gradle.plugin.KotlinSourceSet
 import org.jetbrains.kotlin.gradle.plugin.KotlinTarget
+import org.jetbrains.kotlin.gradle.plugin.mpp.JsIrCompilationDetails
 import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinJsCompilation
 import org.jetbrains.kotlin.gradle.targets.js.dukat.ExternalsOutputFormat
-import org.jetbrains.kotlin.gradle.utils.lowerCamelCaseName
 
 class KotlinJsIrCompilation(
     target: KotlinTarget,
     name: String
-) : KotlinJsCompilation(target, name) {
+) : KotlinJsCompilation(JsIrCompilationDetails(target, name)) {
 
     override val externalsOutputFormat: ExternalsOutputFormat = ExternalsOutputFormat.SOURCE
 
     internal val allSources: MutableSet<SourceDirectorySet> = mutableSetOf()
-
-    override fun addSourcesToCompileTask(sourceSet: KotlinSourceSet, addAsCommonSources: Lazy<Boolean>) {
-        super.addSourcesToCompileTask(sourceSet, addAsCommonSources)
-        allSources.add(sourceSet.kotlin)
-    }
-
-    override val disambiguationClassifierInPlatform: String?
-        get() = (target as KotlinJsIrTarget).disambiguationClassifierInPlatform
-
-    override val defaultSourceSetName: String
-        get() {
-            val target = target as KotlinJsIrTarget
-            return lowerCamelCaseName(
-                if (target.mixedMode)
-                    target.disambiguationClassifierInPlatform
-                else
-                    target.disambiguationClassifier,
-                compilationPurpose
-            )
-        }
 }

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/jvm/KotlinJvmAndroidCompilation.kt

@@ -1,4 +1,4 @@
- /*
+/*
  * Copyright 2010-2018 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.
  */
@@ -17,43 +17,24 @@ import org.jetbrains.kotlin.gradle.plugin.KotlinCompilation
 import org.jetbrains.kotlin.gradle.plugin.getJavaTaskProvider
 import org.jetbrains.kotlin.gradle.plugin.getTestedVariantData
 
- class KotlinJvmAndroidCompilation(
-     target: KotlinAndroidTarget,
-     name: String
- ) : AbstractKotlinCompilationToRunnableFiles<KotlinJvmOptions>(target, name) {
-
-    override val kotlinOptions: KotlinJvmOptions = KotlinJvmOptionsImpl()
+class KotlinJvmAndroidCompilation(
+    target: KotlinAndroidTarget,
+    name: String
+) : AbstractKotlinCompilationToRunnableFiles<KotlinJvmOptions>(AndroidCompilationDetails(target, name)) {
 
     lateinit var androidVariant: BaseVariant
         internal set
 
-     override val compileKotlinTask: org.jetbrains.kotlin.gradle.tasks.KotlinCompile
-         get() = super.compileKotlinTask as org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+    @Suppress("UnstableApiUsage")
+    internal val testedVariantArtifacts: Property<FileCollection> = target.project.objects.property(FileCollection::class.java)
 
-     @Suppress("UNCHECKED_CAST")
-     override val compileKotlinTaskProvider: TaskProvider<out org.jetbrains.kotlin.gradle.tasks.KotlinCompile>
-         get() = super.compileKotlinTaskProvider as TaskProvider<out org.jetbrains.kotlin.gradle.tasks.KotlinCompile>
+    override val compileKotlinTask: org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+        get() = super.compileKotlinTask as org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 
+    @Suppress("UNCHECKED_CAST")
+    override val compileKotlinTaskProvider: TaskProvider<out org.jetbrains.kotlin.gradle.tasks.KotlinCompile>
+        get() = super.compileKotlinTaskProvider as TaskProvider<out org.jetbrains.kotlin.gradle.tasks.KotlinCompile>
 
-     @Suppress("UnstableApiUsage")
-     internal val testedVariantArtifacts: Property<FileCollection> = target.project.objects.property(FileCollection::class.java)
-
-     override val friendArtifacts: FileCollection get() = target.project.files(super.friendArtifacts, testedVariantArtifacts)
-
-     override fun addAssociateCompilationDependencies(other: KotlinCompilation<*>) {
-         if ((other as? KotlinJvmAndroidCompilation)?.androidVariant != getTestedVariantData(androidVariant)) {
-             super.addAssociateCompilationDependencies(other)
-         } // otherwise, do nothing: the Android Gradle plugin adds these dependencies for us, we don't need to add them to the classpath
-     }
-
-     override val relatedConfigurationNames: List<String>
-         get() = super.relatedConfigurationNames + listOf(
-             "${androidVariant.name}ApiElements",
-             "${androidVariant.name}RuntimeElements",
-             androidVariant.compileConfiguration.name,
-             androidVariant.runtimeConfiguration.name
-         )
-
-     val compileJavaTaskProvider: TaskProvider<out JavaCompile>?
-         get() = androidVariant.getJavaTaskProvider()
- }
+    val compileJavaTaskProvider: TaskProvider<out JavaCompile>?
+        get() = androidVariant.getJavaTaskProvider()
+}

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/jvm/KotlinJvmCompilation.kt

@@ -1,4 +1,4 @@
- /*
+/*
  * Copyright 2010-2018 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.
  */
@@ -12,14 +12,13 @@ import org.gradle.api.tasks.TaskProvider
 import org.jetbrains.kotlin.gradle.dsl.KotlinJvmOptions
 import org.jetbrains.kotlin.gradle.dsl.KotlinJvmOptionsImpl
 import org.jetbrains.kotlin.gradle.plugin.KotlinCompilationWithResources
+import org.jetbrains.kotlin.gradle.plugin.KotlinTarget
 import org.jetbrains.kotlin.gradle.targets.jvm.KotlinJvmTarget
 
 open class KotlinJvmCompilation(
-    override val target: KotlinJvmTarget,
-    name: String
-) : AbstractKotlinCompilationToRunnableFiles<KotlinJvmOptions>(target, name), KotlinCompilationWithResources<KotlinJvmOptions> {
-
-    override val kotlinOptions: KotlinJvmOptions = KotlinJvmOptionsImpl()
+    compilationDetails: CompilationDetailsWithRuntime<KotlinJvmOptions>,
+) : AbstractKotlinCompilationToRunnableFiles<KotlinJvmOptions>(compilationDetails), KotlinCompilationWithResources<KotlinJvmOptions> {
+    override val target: KotlinJvmTarget get() = compilationDetails.target as KotlinJvmTarget
 
     override val processResourcesTaskName: String
         get() = disambiguateName("processResources")

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/jvm/KotlinJvmCompilationFactory.kt

@@ -6,6 +6,7 @@
 @file:Suppress("PackageDirectoryMismatch") // Old package for compatibility
 package org.jetbrains.kotlin.gradle.plugin.mpp
 
+import org.jetbrains.kotlin.gradle.dsl.KotlinJvmOptionsImpl
 import org.jetbrains.kotlin.gradle.targets.jvm.KotlinJvmTarget
 
 open class KotlinJvmCompilationFactory(
@@ -15,5 +16,7 @@ open class KotlinJvmCompilationFactory(
         get() = KotlinJvmCompilation::class.java
 
     override fun create(name: String): KotlinJvmCompilation =
-        KotlinJvmCompilation(target, name)
+        KotlinJvmCompilation(
+            DefaultCompilationDetailsWithRuntime(target, name) { KotlinJvmOptionsImpl() }
+        )
 }

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/jvm/KotlinWithJavaCompilation.kt

@@ -1,4 +1,4 @@
- /*
+/*
  * Copyright 2010-2018 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.
  */
@@ -16,30 +16,17 @@ import org.jetbrains.kotlin.gradle.plugin.KotlinCompilationOutput
 import org.jetbrains.kotlin.gradle.plugin.KotlinCompilationWithResources
 import org.jetbrains.kotlin.gradle.tasks.AbstractKotlinCompile
 
- class KotlinWithJavaCompilation<KotlinOptionsType : KotlinCommonOptions>(
+class KotlinWithJavaCompilation<KotlinOptionsType : KotlinCommonOptions>(
     target: KotlinWithJavaTarget<KotlinOptionsType>,
     name: String,
-    override val kotlinOptions: KotlinOptionsType
-) : AbstractKotlinCompilationToRunnableFiles<KotlinOptionsType>(target, name), KotlinCompilationWithResources<KotlinOptionsType> {
+    kotlinOptions: KotlinOptionsType
+) : AbstractKotlinCompilationToRunnableFiles<KotlinOptionsType>(WithJavaCompilationDetails(target, name) { kotlinOptions }),
+    KotlinCompilationWithResources<KotlinOptionsType> {
     lateinit var javaSourceSet: SourceSet
 
-    override val output: KotlinCompilationOutput by lazy { KotlinWithJavaCompilationOutput(this) }
-
     override val processResourcesTaskName: String
         get() = javaSourceSet.processResourcesTaskName
 
-    override var runtimeDependencyFiles: FileCollection
-        get() = javaSourceSet.runtimeClasspath
-        set(value) {
-            javaSourceSet.runtimeClasspath = value
-        }
-
-    override val runtimeDependencyConfigurationName: String
-        get() = javaSourceSet.runtimeClasspathConfigurationName
-
-    override val compileDependencyConfigurationName: String
-        get() = javaSourceSet.compileClasspathConfigurationName
-
     override val runtimeOnlyConfigurationName: String
         get() = javaSourceSet.runtimeOnlyConfigurationName
 
@@ -55,18 +42,6 @@ import org.jetbrains.kotlin.gradle.tasks.AbstractKotlinCompile
     override val compileAllTaskName: String
         get() = javaSourceSet.classesTaskName
 
-    override var compileDependencyFiles: FileCollection
-        get() = javaSourceSet.compileClasspath
-        set(value) {
-            javaSourceSet.compileClasspath = value
-        }
-
-     override fun addAssociateCompilationDependencies(other: KotlinCompilation<*>) {
-         if (name != SourceSet.TEST_SOURCE_SET_NAME || other.name != SourceSet.MAIN_SOURCE_SET_NAME) {
-             super.addAssociateCompilationDependencies(other)
-         } // otherwise, do nothing: the Java Gradle plugin adds these dependencies for us, we don't need to add them to the classpath
-     }
-
     fun source(javaSourceSet: SourceSet) {
         with(target.project) {
             afterEvaluate {

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/metadata/KotlinMetadataTargetConfigurator.kt

@@ -287,6 +287,8 @@ class KotlinMetadataTargetConfigurator :
     ): AbstractKotlinCompilation<*> {
         val project = target.project
 
+        check(!project.hasKpmModel) { "KotlinMetadataTargetConfigurator cannot work with KPM!" }
+
         val compilationName = sourceSet.name
 
         val platformCompilations = compilationsBySourceSets(project)
@@ -304,7 +306,9 @@ class KotlinMetadataTargetConfigurator :
 
         return compilationFactory.create(compilationName).apply {
             target.compilations.add(this@apply)
-            addExactSourceSetsEagerly(setOf(sourceSet))
+
+            (compilationDetails as DefaultCompilationDetails<*>).addExactSourceSetsEagerly(setOf(sourceSet))
+
             configureMetadataDependenciesForCompilation(this@apply)
 
             if (!isHostSpecific) {

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/native/KotlinNativeCompilation.kt

@@ -14,6 +14,7 @@ import org.gradle.api.file.FileCollection
 import org.gradle.api.tasks.TaskProvider
 import org.gradle.util.ConfigureUtil
 import org.jetbrains.kotlin.gradle.dsl.KotlinCommonOptions
+import org.jetbrains.kotlin.gradle.dsl.KotlinMultiplatformCommonOptionsImpl
 import org.jetbrains.kotlin.gradle.plugin.*
 import org.jetbrains.kotlin.gradle.plugin.mpp.pm20.KotlinNativeCompilationData
 import org.jetbrains.kotlin.gradle.plugin.mpp.pm20.KotlinNativeFragmentMetadataCompilationData
@@ -54,12 +55,12 @@ internal class NativeCompileOptions(languageSettingsProvider: () -> LanguageSett
 }
 
 abstract class AbstractKotlinNativeCompilation(
-    target: KotlinTarget,
     override val konanTarget: KonanTarget,
-    compilationName: String
-) : AbstractKotlinCompilation<KotlinCommonOptions>(target, compilationName), KotlinNativeCompilationData<KotlinCommonOptions> {
-
-    override val kotlinOptions: KotlinCommonOptions = NativeCompileOptions { defaultSourceSet.languageSettings }
+    compilationDetails: CompilationDetails<KotlinCommonOptions>
+) : AbstractKotlinCompilation<KotlinCommonOptions>(
+    compilationDetails
+),
+    KotlinNativeCompilationData<KotlinCommonOptions> {
 
     override val compileKotlinTask: KotlinNativeCompile
         get() = super.compileKotlinTask as KotlinNativeCompile
@@ -68,10 +69,6 @@ abstract class AbstractKotlinNativeCompilation(
     override val compileKotlinTaskProvider: TaskProvider<out KotlinNativeCompile>
         get() = super.compileKotlinTaskProvider as TaskProvider<out KotlinNativeCompile>
 
-    override fun addSourcesToCompileTask(sourceSet: KotlinSourceSet, addAsCommonSources: Lazy<Boolean>) {
-        addSourcesToKotlinNativeCompileTask(project, compileKotlinTaskName, { sourceSet.kotlin }, addAsCommonSources)
-    }
-
     internal val useGenericPluginArtifact: Boolean
         get() = project.nativeUseEmbeddableCompilerJar
 
@@ -96,12 +93,14 @@ internal fun addSourcesToKotlinNativeCompileTask(
 }
 
 class KotlinNativeCompilation(
-    override val target: KotlinNativeTarget,
     konanTarget: KonanTarget,
-    name: String
-) : AbstractKotlinNativeCompilation(target, konanTarget, name),
+    details: CompilationDetails<KotlinCommonOptions>
+) : AbstractKotlinNativeCompilation(konanTarget, details),
     KotlinCompilationWithResources<KotlinCommonOptions> {
 
+    override val target: KotlinNativeTarget
+        get() = super.target as KotlinNativeTarget
+
     // Interop DSL.
     val cinterops = project.container(DefaultCInteropSettings::class.java) { cinteropName ->
         DefaultCInteropSettings(project, cinteropName, this)
@@ -114,50 +113,24 @@ class KotlinNativeCompilation(
     override val processResourcesTaskName: String
         get() = disambiguateName("processResources")
 
-    override val compileDependencyConfigurationName: String
-        get() = lowerCamelCaseName(
-            target.disambiguationClassifier,
-            compilationPurpose.takeIf { it != KotlinCompilation.MAIN_COMPILATION_NAME }.orEmpty(),
-            "compileKlibraries"
-        )
-
-    override val compileAllTaskName: String
-        get() = lowerCamelCaseName(target.disambiguationClassifier, compilationPurpose, "klibrary")
-
     val binariesTaskName: String
         get() = lowerCamelCaseName(target.disambiguationClassifier, compilationPurpose, "binaries")
-
-    override fun addAssociateCompilationDependencies(other: KotlinCompilation<*>) {
-        compileDependencyFiles += other.output.classesDirs + project.filesProvider { other.compileDependencyFiles }
-
-        target.project.configurations.named(implementationConfigurationName).configure { configuration ->
-            configuration.extendsFrom(target.project.configurations.findByName(other.implementationConfigurationName))
-        }
-    }
 }
 
-class KotlinSharedNativeCompilation(override val target: KotlinMetadataTarget, val konanTargets: List<KonanTarget>, name: String) :
+class KotlinSharedNativeCompilation(
+    target: KotlinMetadataTarget,
+    val konanTargets: List<KonanTarget>, name: String) :
     KotlinNativeFragmentMetadataCompilationData,
     AbstractKotlinNativeCompilation(
-        target,
         // TODO: this will end up as '-target' argument passed to K2Native, which is wrong.
         // Rewrite this when we'll compile native-shared source-sets against commonized platform libs
         // We find any konan target that is enabled on the current host in order to pass the checks that avoid compiling the code otherwise.
         konanTargets.find { it.enabledOnCurrentHost } ?: konanTargets.first(),
-        name
+        SharedNativeCompilationDetails(target, name) { NativeCompileOptions { defaultSourceSet.languageSettings } }
     ),
     KotlinMetadataCompilation<KotlinCommonOptions> {
 
-    override val friendArtifacts: FileCollection
-        get() = super.friendArtifacts.plus(run {
-            val project = target.project
-            val friendSourceSets = getVisibleSourceSetsFromAssociateCompilations(project, defaultSourceSet).toMutableSet().apply {
-                // TODO: implement proper dependsOn/refines compiler args for Kotlin/Native and pass the dependsOn klibs separately;
-                //       But for now, those dependencies don't have any special semantics, so passing all them as friends works, too
-                addAll(defaultSourceSet.resolveAllDependsOnSourceSets())
-            }
-            project.files(friendSourceSets.mapNotNull { project.getMetadataCompilationForSourceSet(it)?.output?.classesDirs })
-        })
+    override val target: KotlinMetadataTarget get() = super.target as KotlinMetadataTarget
 
     override val isActive: Boolean
         get() = true // old plugin only creates necessary compilations

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/native/KotlinNativeCompilationFactory.kt

@@ -17,11 +17,15 @@ class KotlinNativeCompilationFactory(
         get() = KotlinNativeCompilation::class.java
 
     override fun create(name: String): KotlinNativeCompilation =
-        // TODO: Validate compilation free args using the [CompilationFreeArgsValidator]
-        //       when the compilation and the link args are separated (see KT-33717).
-        // Note: such validation should be done in the whenEvaluate block because
+    // TODO: Validate compilation free args using the [CompilationFreeArgsValidator]
+    //       when the compilation and the link args are separated (see KT-33717).
+    // Note: such validation should be done in the whenEvaluate block because
         // a user can change args during project configuration.
-        KotlinNativeCompilation(target, target.konanTarget, name)
+
+        KotlinNativeCompilation(
+            target.konanTarget,
+            NativeCompilationDetails(target, name) { NativeCompileOptions { defaultSourceSet.languageSettings } }
+        )
 }
 
 class KotlinSharedNativeCompilationFactory(

libraries/tools/kotlin-gradle-plugin/src/test/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/internal/KotlinCompilationsModuleGroupsTest.kt

@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.gradle.plugin.mpp.internal
 
 import org.jetbrains.kotlin.gradle.plugin.KotlinCompilation
+import org.jetbrains.kotlin.gradle.plugin.mpp.pm20.KotlinCompilationData
 import org.jetbrains.kotlin.gradle.plugin.sources.MockKotlinCompilation
 import org.jetbrains.kotlin.gradle.plugin.sources.MockKotlinSourceSet
 import org.junit.Before
@@ -28,7 +29,7 @@ class KotlinCompilationsModuleGroupsTest {
         assertEquals(a, instance.getModuleLeader(a))
     }
 
-    private fun assertLeader(leader: KotlinCompilation<*>, vararg ofCompilations: KotlinCompilation<*>) {
+    private fun assertLeader(leader: KotlinCompilationData<*>, vararg ofCompilations: KotlinCompilationData<*>) {
         val leadersForModules = ofCompilations.map { instance.getModuleLeader(it) }
         assertEquals(leadersForModules.map { leader }, leadersForModules)
     }

libraries/tools/kotlin-gradle-plugin/src/test/kotlin/org/jetbrains/kotlin/gradle/plugin/sources/SourceSetVisibilityInferenceTest.kt

@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.gradle.plugin.sources
 
 import groovy.lang.Closure
+import org.gradle.api.Project
 import org.gradle.api.attributes.AttributeContainer
 import org.gradle.api.file.FileCollection
 import org.gradle.api.file.SourceDirectorySet
@@ -13,6 +14,8 @@ import org.gradle.api.tasks.TaskProvider
 import org.jetbrains.kotlin.gradle.dsl.KotlinCommonOptions
 import org.jetbrains.kotlin.gradle.dsl.KotlinCompile
 import org.jetbrains.kotlin.gradle.plugin.*
+import org.jetbrains.kotlin.gradle.plugin.mpp.pm20.KotlinCompilationData
+import org.jetbrains.kotlin.project.model.LanguageSettings
 import kotlin.test.Test
 import kotlin.test.assertEquals
 import kotlin.test.assertFailsWith
@@ -271,7 +274,7 @@ class MockKotlinSourceSet(private val name: String) : KotlinSourceSet {
 class MockKotlinCompilation(
     override val compilationName: String,
     override val defaultSourceSet: KotlinSourceSet
-) : KotlinCompilation<KotlinCommonOptions> {
+) : KotlinCompilation<KotlinCommonOptions>, KotlinCompilationData<KotlinCommonOptions> {
     override val kotlinSourceSets: Set<KotlinSourceSet> = setOf(defaultSourceSet)
 
     override val allKotlinSourceSets: Set<KotlinSourceSet>
@@ -297,6 +300,8 @@ class MockKotlinCompilation(
 
     override fun defaultSourceSet(configure: KotlinSourceSet.() -> Unit) = defaultSourceSet.run(configure)
 
+    override val compilationPurpose: String get() = compilationName
+
     //region Not implemented
     override val target: KotlinTarget get() = throw UnsupportedOperationException()
     override val compileKotlinTaskProvider: TaskProvider<out KotlinCompile<KotlinCommonOptions>> get() = throw UnsupportedOperationException()
@@ -322,7 +327,15 @@ class MockKotlinCompilation(
     override fun attributes(configure: Closure<*>) = throw UnsupportedOperationException()
     override val compileAllTaskName: String get() = throw UnsupportedOperationException()
     override val moduleName: String get() = throw UnsupportedOperationException()
+    override fun toString(): String = "compilation '${name}'"
+    override val project: Project get() = throw UnsupportedOperationException()
+    override val owner: Any get() = throw UnsupportedOperationException()
+    override val compilationClassifier: String get() = throw UnsupportedOperationException()
+    override val kotlinSourceDirectoriesByFragmentName: Map<String, SourceDirectorySet> get() = throw UnsupportedOperationException()
+    override val languageSettings: LanguageSettings get() = throw UnsupportedOperationException()
+    override val platformType: KotlinPlatformType get() = throw UnsupportedOperationException()
+    override val ownModuleName: String get() = throw UnsupportedOperationException()
+    override val friendPaths: Iterable<FileCollection> get() = throw UnsupportedOperationException()
     //endregion
 
-    override fun toString(): String = "compilation '${name}'"
 }