Restructure source JARs logic, move it to components management

Move the logic of attaching a source JAR to a publication to the
components management part, as building a source JAR will be done
differently for Android.

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

@@ -11,6 +11,7 @@ import org.gradle.api.Project
 import org.gradle.api.attributes.Attribute
 import org.gradle.api.attributes.AttributeContainer
 import org.gradle.api.internal.FeaturePreviews
+import org.gradle.api.internal.component.SoftwareComponentInternal
 import org.gradle.api.internal.file.FileResolver
 import org.gradle.api.internal.plugins.DslObject
 import org.gradle.api.plugins.JavaBasePlugin
@@ -29,6 +30,7 @@ import org.jetbrains.kotlin.gradle.dsl.kotlinExtension
 import org.jetbrains.kotlin.gradle.plugin.*
 import org.jetbrains.kotlin.gradle.plugin.sources.DefaultLanguageSettingsBuilder
 import org.jetbrains.kotlin.gradle.utils.SingleWarningPerBuild
+import org.jetbrains.kotlin.gradle.utils.lowerCamelCaseName
 import org.jetbrains.kotlin.konan.target.HostManager
 import org.jetbrains.kotlin.konan.target.presetName
 
@@ -87,8 +89,6 @@ class KotlinMultiplatformPlugin(
             KotlinMetadataTargetPreset(project, instantiator, fileResolver, kotlinPluginVersion),
             METADATA_TARGET_NAME
         )
-        configureSourceJars(project)
-
         configurePublishingWithMavenPublish(project)
 
         // propagate compiler plugin options to the source set language settings
@@ -190,8 +190,9 @@ class KotlinMultiplatformPlugin(
                     // do this in whenEvaluated since older Gradle versions seem to check the files in the variant eagerly:
                     project.whenEvaluated {
                         from(variant)
-                        (project.tasks.findByName(sourcesJarTaskName) as Jar?)?.let { sourcesJar ->
-                            artifact(sourcesJar)
+                        if (variant is SoftwareComponentInternal) {
+                            variant.usages.filterIsInstance<KotlinUsageContext>().map { it.sourcesArtifact }.distinct()
+                                .forEach { artifact(it) }
                         }
                     }
                     (this as MavenPublicationInternal).publishWithOriginalFileName()
@@ -200,31 +201,7 @@ class KotlinMultiplatformPlugin(
 
                 (variant as? KotlinTargetComponentWithPublication)?.publicationDelegate = variantPublication
                 publicationConfigureActions.all { it.execute(variantPublication) }
-        }
-    }
-
-    private val KotlinTarget.sourcesJarTaskName get() = disambiguateName("sourcesJar")
-
-    private fun configureSourceJars(project: Project) = with(project.kotlinExtension as KotlinMultiplatformExtension) {
-        targets.all { target ->
-            val mainCompilation = target.compilations.findByName(KotlinCompilation.MAIN_COMPILATION_NAME)
-            // If a target has no `main` compilation (e.g. Android), don't create the source JAR
-                ?: return@all
-
-            val sourcesJar = project.tasks.create(target.sourcesJarTaskName, Jar::class.java) { sourcesJar ->
-                sourcesJar.appendix = target.targetName.toLowerCase()
-                sourcesJar.classifier = "sources"
             }
-
-            project.afterEvaluate { _ ->
-                val compiledSourceSets = mainCompilation.allKotlinSourceSets
-                compiledSourceSets.forEach { sourceSet ->
-                    sourcesJar.from(sourceSet.kotlin) { copySpec ->
-                        copySpec.into(sourceSet.name)
-                    }
-                }
-            }
-        }
     }
 
     private fun configureSourceSets(project: Project) = with(project.kotlinExtension as KotlinMultiplatformExtension) {
@@ -293,6 +270,28 @@ class KotlinMultiplatformPlugin(
     }
 }
 
+internal fun sourcesJarTask(compilation: KotlinCompilation<*>, componentName: String?, artifactNameAppendix: String): Jar {
+    val project = compilation.target.project
+    val taskName = lowerCamelCaseName(componentName, "sourcesJar")
+
+    (project.tasks.findByName(taskName) as? Jar)?.let { return it }
+
+    val result = project.tasks.create(taskName, Jar::class.java) { sourcesJar ->
+        sourcesJar.appendix = artifactNameAppendix
+        sourcesJar.classifier = "sources"
+    }
+
+    project.whenEvaluated {
+        compilation.allKotlinSourceSets.forEach { sourceSet ->
+            result.from(sourceSet.kotlin) { copySpec ->
+                copySpec.into(sourceSet.name)
+            }
+        }
+    }
+
+    return result
+}
+
 internal fun compilationsBySourceSet(project: Project): Map<KotlinSourceSet, Set<KotlinCompilation<*>>> =
     HashMap<KotlinSourceSet, MutableSet<KotlinCompilation<*>>>().also { result ->
         for (target in project.multiplatformExtension!!.targets) {

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

@@ -38,6 +38,7 @@ object NativeUsage {
 interface KotlinUsageContext : UsageContext {
     val compilation: KotlinCompilation<*>
     val dependencyConfigurationName: String
+    val sourcesArtifact: PublishArtifact?
 }
 
 class DefaultKotlinUsageContext(
@@ -45,6 +46,7 @@ class DefaultKotlinUsageContext(
     private val usage: Usage,
     override val dependencyConfigurationName: String,
     private val publishWithGradleMetadata: Boolean,
+    override val sourcesArtifact: PublishArtifact? = null,
     private val overrideConfigurationArtifacts: Set<PublishArtifact>? = null
 ) : KotlinUsageContext {
 
@@ -73,7 +75,7 @@ class DefaultKotlinUsageContext(
 
     override fun getArtifacts(): Set<PublishArtifact> =
         overrideConfigurationArtifacts ?:
-    // TODO Gradle Java plugin does that in a different way; check whether we can improve this
+        // TODO Gradle Java plugin does that in a different way; check whether we can improve this
         configuration.artifacts
 
     override fun getAttributes(): AttributeContainer =

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

@@ -55,6 +55,9 @@ abstract class KotlinOnlyTargetPreset<T : KotlinCompilation<*>>(
 
         result.compilations.all { compilation ->
             buildCompilationProcessor(compilation).run()
+            if (compilation.name == KotlinCompilation.MAIN_COMPILATION_NAME) {
+                sourcesJarTask(compilation, result.targetName, result.targetName.toLowerCase())
+            }
         }
 
         return result

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

@@ -9,7 +9,9 @@ import org.gradle.api.Action
 import org.gradle.api.DomainObjectSet
 import org.gradle.api.NamedDomainObjectContainer
 import org.gradle.api.Project
+import org.gradle.api.artifacts.ConfigurablePublishArtifact
 import org.gradle.api.artifacts.Dependency
+import org.gradle.api.artifacts.PublishArtifact
 import org.gradle.api.attributes.Attribute
 import org.gradle.api.attributes.AttributeContainer
 import org.gradle.api.attributes.Usage.JAVA_API
@@ -25,6 +27,7 @@ import org.jetbrains.kotlin.gradle.dsl.kotlinExtension
 import org.jetbrains.kotlin.gradle.plugin.*
 import org.jetbrains.kotlin.gradle.utils.isGradleVersionAtLeast
 import org.jetbrains.kotlin.gradle.utils.lowerCamelCaseName
+import org.jetbrains.kotlin.gradle.utils.lowerSpinalCaseName
 import org.jetbrains.kotlin.konan.target.KonanTarget
 
 abstract class AbstractKotlinTarget(
@@ -98,6 +101,8 @@ abstract class AbstractKotlinTarget(
         val publishWithKotlinMetadata = (project.kotlinExtension as? KotlinMultiplatformExtension)?.isGradleMetadataAvailable
             ?: true // In non-MPP project, these usage contexts do not get published anyway
 
+        val sourcesJarArtifact = sourcesJarArtifact(producingCompilation, componentName, artifactNameAppendix)
+
         // Here, `JAVA_API` and `JAVA_RUNTIME_JARS` are used intentionally as Gradle needs this for
         // ordering of the usage contexts (prioritizing the dependencies) when merging them into the POM;
         // These Java usages should not be replaced with the custom Kotlin usages.
@@ -109,11 +114,36 @@ abstract class AbstractKotlinTarget(
                 producingCompilation,
                 project.usageByName(usageName),
                 dependenciesConfigurationName,
-                publishWithKotlinMetadata
-                )
+                publishWithKotlinMetadata,
+                sourcesJarArtifact
+            )
         }
     }
 
+    protected fun sourcesJarArtifact(
+        producingCompilation: KotlinCompilation<*>,
+        componentName: String,
+        artifactNameAppendix: String,
+        classifierPrefix: String? = null
+    ): PublishArtifact {
+        val sourcesJarTask = sourcesJarTask(producingCompilation, componentName, artifactNameAppendix)
+        val sourceArtifactConfigurationName = producingCompilation.disambiguateName("sourceArtifacts")
+        val sourcesJarArtifact = producingCompilation.target.project.run {
+            (configurations.findByName(sourceArtifactConfigurationName) ?: run {
+                val configuration = configurations.create(sourceArtifactConfigurationName) {
+                    it.isCanBeResolved = false
+                    it.isCanBeConsumed = false
+                }
+                artifacts.add(sourceArtifactConfigurationName, sourcesJarTask)
+                configuration
+            }).artifacts.single().apply {
+                this as ConfigurablePublishArtifact
+                classifier = lowerSpinalCaseName(classifierPrefix, "sources")
+            }
+        }
+        return sourcesJarArtifact
+    }
+
     @Suppress("UNCHECKED_CAST")
     internal val publicationConfigureActions =
         WrapUtil.toDomainObjectSet(Action::class.java) as DomainObjectSet<Action<MavenPublication>>