[Gradle] Ensure java source sets being created eagerly for 'withJava'

^KT-60158 Verification Pending

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/NewMultiplatformIT.kt

@@ -545,9 +545,15 @@ open class NewMultiplatformIT : BaseGradleIT() {
             }
 
             gradleBuildScript().modify {
-                if (testJavaSupportInJvmTargets) {
+                """
+                    apply plugin: 'com.github.johnrengelman.shadow'
+                    apply plugin: 'application'
+                    apply plugin: 'kotlin-kapt' // Check that Kapts works, generates and compiles sources
+                """.trimIndent() + if (testJavaSupportInJvmTargets) {
                     it + "\nkotlin.jvm(\"jvm6\") { " +
-                            "${KotlinJvmTarget::withJava.name.plus("();").repeat(2)} " + // also check that the function is idempotent
+                            "${
+                                KotlinJvmTarget::withJava.name.plus("();").repeat(2)
+                            } " + // also check that the function is idempotent
                             "}"
                 } else {
                     it.replace("presets.jvm", "presets.jvmWithJava").replace("jvm(", "targetFromPreset(presets.jvmWithJava, ")
@@ -562,10 +568,6 @@ open class NewMultiplatformIT : BaseGradleIT() {
                         }
                     }
                     
-                    apply plugin: 'com.github.johnrengelman.shadow'
-                    apply plugin: 'application'
-                    apply plugin: 'kotlin-kapt' // Check that Kapts works, generates and compiles sources
-                    
                     mainClassName = 'com.example.lib.CommonKt'
                     
                     dependencies {

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

@@ -29,7 +29,7 @@ import java.util.concurrent.Callable
 internal abstract class KotlinSourceSetProcessor<T : AbstractKotlinCompile<*>>(
     val tasksProvider: KotlinTasksProvider,
     val taskDescription: String,
-    kotlinCompilation: KotlinCompilationInfo
+    kotlinCompilation: KotlinCompilationInfo,
 ) : KotlinCompilationProcessor<T>(kotlinCompilation) {
     protected abstract fun doTargetSpecificProcessing()
     protected val logger = Logging.getLogger(this.javaClass)!!
@@ -41,13 +41,7 @@ internal abstract class KotlinSourceSetProcessor<T : AbstractKotlinCompile<*>>(
     protected val javaSourceSet: SourceSet?
         get() = when (val compilation = compilationInfo.safeAs<KotlinCompilationInfo.TCS>()?.origin) {
             is KotlinWithJavaCompilation<*, *> -> compilation.javaSourceSet
-            is KotlinJvmCompilation -> if (compilation.target.withJavaEnabled) {
-                project.variantImplementationFactory<JavaSourceSetsAccessor.JavaSourceSetsAccessorVariantFactory>()
-                    .getInstance(project)
-                    .sourceSets
-                    .maybeCreate(compilation.name)
-            } else null
-
+            is KotlinJvmCompilation -> compilation.javaSourceSet.getOrNull()
             else -> null
         }
 
@@ -154,4 +148,4 @@ internal abstract class KotlinSourceSetProcessor<T : AbstractKotlinCompile<*>>(
     }
 
     protected abstract fun doRegisterTask(project: Project, taskName: String): TaskProvider<out T>
-}
+}

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

@@ -7,9 +7,11 @@
 package org.jetbrains.kotlin.gradle.plugin.mpp
 
 import org.gradle.api.provider.Provider
+import org.gradle.api.tasks.SourceSet
 import org.gradle.api.tasks.TaskProvider
 import org.gradle.api.tasks.compile.JavaCompile
-import org.jetbrains.kotlin.gradle.dsl.*
+import org.jetbrains.kotlin.gradle.dsl.KotlinJvmCompilerOptions
+import org.jetbrains.kotlin.gradle.dsl.KotlinJvmOptions
 import org.jetbrains.kotlin.gradle.plugin.HasCompilerOptions
 import org.jetbrains.kotlin.gradle.plugin.KotlinCompilationWithResources
 import org.jetbrains.kotlin.gradle.plugin.internal.JavaSourceSetsAccessor
@@ -17,10 +19,13 @@ import org.jetbrains.kotlin.gradle.plugin.mpp.compilationImpl.KotlinCompilationI
 import org.jetbrains.kotlin.gradle.plugin.variantImplementationFactory
 import org.jetbrains.kotlin.gradle.targets.jvm.KotlinJvmTarget
 import org.jetbrains.kotlin.gradle.tasks.KotlinCompilationTask
+import org.jetbrains.kotlin.gradle.utils.LenientFuture
+import org.jetbrains.kotlin.gradle.utils.future
+import org.jetbrains.kotlin.gradle.utils.lenient
 import javax.inject.Inject
 
 open class KotlinJvmCompilation @Inject internal constructor(
-    compilation: KotlinCompilationImpl
+    compilation: KotlinCompilationImpl,
 ) : AbstractKotlinCompilationToRunnableFiles<KotlinJvmOptions>(compilation),
     KotlinCompilationWithResources<KotlinJvmOptions> {
 
@@ -62,14 +67,18 @@ open class KotlinJvmCompilation @Inject internal constructor(
      * will be enabled after call to this method.
      */
     internal val compileJavaTaskProviderSafe: Provider<JavaCompile> = target.project.providers
-        .provider { if (target.withJavaEnabled) Unit else null }
-        .map {
-            project.javaSourceSets.getByName(compilationName).compileJavaTaskName
-        }
-        .flatMap {
-            project.tasks.named(it, JavaCompile::class.java)
+        .provider { javaSourceSet.getOrNull() }
+        .flatMap { javaSourceSet ->
+            @Suppress("RedundantRequireNotNullCall") // IDE and CLI disagree here
+            checkNotNull(javaSourceSet)
+            project.tasks.named(javaSourceSet.compileJavaTaskName, JavaCompile::class.java)
         }
 
+    internal val javaSourceSet: LenientFuture<SourceSet> = target.project.future {
+        target.withJavaEnabledFuture.await()
+        target.project.javaSourceSets.maybeCreate(compilationName)
+    }.lenient
+
     override val processResourcesTaskName: String
         get() = compilation.processResourcesTaskName ?: error("Missing 'processResourcesTaskName'")
 }

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

@@ -30,8 +30,9 @@ import org.jetbrains.kotlin.gradle.targets.jvm.tasks.KotlinJvmRunDsl
 import org.jetbrains.kotlin.gradle.targets.jvm.tasks.KotlinJvmRunDslImpl
 import org.jetbrains.kotlin.gradle.targets.jvm.tasks.registerMainRunTask
 import org.jetbrains.kotlin.gradle.tasks.withType
+import org.jetbrains.kotlin.gradle.utils.*
+import org.jetbrains.kotlin.gradle.utils.CompletableFuture
 import org.jetbrains.kotlin.gradle.utils.Future
-import org.jetbrains.kotlin.gradle.utils.addExtendsFromRelation
 import org.jetbrains.kotlin.gradle.utils.findAppliedAndroidPluginIdOrNull
 import org.jetbrains.kotlin.gradle.utils.future
 import org.jetbrains.kotlin.utils.addToStdlib.cast
@@ -90,10 +91,16 @@ abstract class KotlinJvmTarget @Inject constructor(
         mainRun.await()?.configure()
     }
 
+    /**
+     * Future that will complete once [withJava] is called and java support for this target
+     * was established.
+     */
+    internal val withJavaEnabledFuture: Future<Unit> get() = withJavaEnabledFutureImpl
+    private val withJavaEnabledFutureImpl = CompletableFuture<Unit>()
+
     var withJavaEnabled = false
         private set
 
-
     @Suppress("unused") // user DSL
     fun withJava() {
         if (withJavaEnabled)
@@ -164,6 +171,8 @@ abstract class KotlinJvmTarget @Inject constructor(
                 copyUserDefinedAttributesToJavaConfigurations(javaSourceSet)
             }
         }
+
+        withJavaEnabledFutureImpl.complete(Unit)
     }
 
     private fun setupJavaSourceSetSourcesAndResources(