[Gradle] Associate Android java sources with related Kotlin Source Set

Java sources can be produced by the task or can be configured with
task dependencies. Previously sources were included into task directly
now they are properly configured with Kotlin Android Source Set.

^KT-63753 Verification Pending
^KT-65426 Verification Pending

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

@@ -973,11 +973,6 @@ class KotlinAndroidMppIT : KGPBaseTest() {
             defaultBuildOptions.copy(androidVersion = agpVersion),
             buildJdk = jdkVersion.location
         ) {
-            // Hacks for TODO: KT-65426
-            val appPath = subProject("app").projectPath
-            appPath.resolve("src/main/java/app/example/com/app_sample").deleteRecursively()
-            appPath.resolve("src/commonMain/kotlin/A.kt").replaceText("expect fun f(): Unit", "")
-
             // Code copied from the reproducer from KT-63753
             subProject("app").buildGradleKts.appendText(
                 """

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

@@ -28,7 +28,7 @@ internal val singleTargetAndroidSourceSetLayout = KotlinAndroidSourceSetLayout(
         GradleConventionAddKotlinSourcesToAndroidSourceSetConfigurator,
         Agp7AddKotlinSourcesToAndroidSourceSetConfigurator
             .onlyIf { AndroidGradlePluginVersion.current >= "7.0.0" },
-
+        KotlinAndroidJavaSourceDirConfigurator,
         SingleTargetSourceDirConfigurator,
     ),
     checker = KotlinAndroidSourceSetLayoutChecker()
@@ -43,6 +43,7 @@ internal val multiplatformAndroidSourceSetLayoutV1 = KotlinAndroidSourceSetLayou
         GradleConventionAddKotlinSourcesToAndroidSourceSetConfigurator,
         Agp7AddKotlinSourcesToAndroidSourceSetConfigurator
             .onlyIf { AndroidGradlePluginVersion.current >= "7.0.0" },
+        KotlinAndroidJavaSourceDirConfigurator,
         MultiplatformAndroidResourceDirConfigurator,
         MultiplatformLayoutV1DependsOnConfigurator,
         MultiplatformLayoutV1SourceDirConfigurator
@@ -62,6 +63,7 @@ internal val multiplatformAndroidSourceSetLayoutV2 = KotlinAndroidSourceSetLayou
         MultiplatformLayoutV2DependsOnConfigurator,
         Agp7AddKotlinSourcesToAndroidSourceSetConfigurator
             .onlyIf { AndroidGradlePluginVersion.current >= "7.0.0" },
+        KotlinAndroidJavaSourceDirConfigurator,
         MultiplatformLayoutV2SourceDirConfigurator,
         MultiplatformLayoutV2DefaultManifestLocationConfigurator
     ),

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

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2010-2024 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+@file:Suppress("TYPEALIAS_EXPANSION_DEPRECATION")
+
+package org.jetbrains.kotlin.gradle.plugin.sources.android.configurator
+
+import org.jetbrains.kotlin.gradle.plugin.KotlinSourceSet
+import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinAndroidTarget
+import org.jetbrains.kotlin.gradle.utils.DeprecatedAndroidSourceSet
+import org.jetbrains.kotlin.gradle.utils.fileCollectionFromConfigurableFileTree
+import org.jetbrains.kotlin.gradle.utils.filesProvider
+
+internal object KotlinAndroidJavaSourceDirConfigurator : KotlinAndroidSourceSetConfigurator {
+    override fun configure(target: KotlinAndroidTarget, kotlinSourceSet: KotlinSourceSet, androidSourceSet: DeprecatedAndroidSourceSet) {
+        val project = target.project
+
+        kotlinSourceSet.kotlin.srcDir(project.provider {
+            // getSourceDirectoryTrees() is not lazy, thus it should be wrapped with provider
+            androidSourceSet.java.getSourceDirectoryTrees().map { sources ->
+                project.fileCollectionFromConfigurableFileTree(sources)
+            }
+        })
+    }
+}

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/sources/android/configurator/MultiplatformLayoutV1SourceDirConfigurator.kt

@@ -27,7 +27,5 @@ internal object MultiplatformLayoutV1SourceDirConfigurator : KotlinAndroidSource
         if (!androidSourceSet.name.startsWith(target.disambiguationClassifier)) {
             kotlinSourceSet.kotlin.srcDir("src/${androidSourceSet.name}/kotlin")
         }
-
-        kotlinSourceSet.kotlin.srcDir(target.project.provider { androidSourceSet.java.srcDirs })
     }
 }

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/sources/android/configurator/MultiplatformLayoutV2SourceDirConfigurator.kt

@@ -15,7 +15,6 @@ internal object MultiplatformLayoutV2SourceDirConfigurator : KotlinAndroidSource
         kotlinSourceSet: KotlinSourceSet,
         @Suppress("TYPEALIAS_EXPANSION_DEPRECATION") androidSourceSet: DeprecatedAndroidSourceSet
     ) {
-        kotlinSourceSet.kotlin.srcDir(target.project.provider { androidSourceSet.java.srcDirs })
         kotlinSourceSet.kotlin.srcDir("src/${androidSourceSet.name}/kotlin")
     }
 }

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

@@ -16,6 +16,5 @@ internal object SingleTargetSourceDirConfigurator : KotlinAndroidSourceSetConfig
         @Suppress("TYPEALIAS_EXPANSION_DEPRECATION") androidSourceSet: DeprecatedAndroidSourceSet
     ) {
         kotlinSourceSet.kotlin.srcDir("src/${androidSourceSet.name}/kotlin")
-        kotlinSourceSet.kotlin.srcDir(target.project.provider { androidSourceSet.java.srcDirs })
     }
 }

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

@@ -230,13 +230,11 @@ internal class AndroidProjectHandler(
 
         val javaTask = variantData.javaCompileProvider
         @Suppress("UNCHECKED_CAST") val kotlinTask = compilation.compileTaskProvider as TaskProvider<KotlinCompile>
-        compilation.androidVariant.forEachJavaSourceDir { sources ->
+        kotlinTask.configure { task ->
-            // It is important to pass exactly `sources.dir` as provider with explicit task dependency
+            variantData.forEachJavaSourceDir { sources ->
-            // Because of the following bugs:
+                task.source(sources.dir)
-            // * https://github.com/gradle/gradle/issues/27881 ConfigurableFileTree.from() doesn't preserve Task Dependencies
+                task.dependsOn(sources)
-            // * https://github.com/gradle/gradle/issues/27882 SourceDirectorySet doesn't accept ConfigurableFileTree
+            }
-            val sourceDirWithTaskDependencies = project.filesProvider(sources) { sources.dir }
-            compilation.defaultSourceSet.kotlin.srcDir(sourceDirWithTaskDependencies)
         }
         wireKotlinTasks(project, compilation, androidPlugin, androidExt, variantData, javaTask, kotlinTask)
     }

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

@@ -6,9 +6,7 @@
 package org.jetbrains.kotlin.gradle.utils
 
 import org.gradle.api.Project
-import org.gradle.api.file.Directory
+import org.gradle.api.file.*
-import org.gradle.api.file.FileCollection
-import org.gradle.api.file.RegularFile
 import org.gradle.api.provider.Provider
 import org.jetbrains.kotlin.gradle.plugin.internal.CustomPropertiesFileValueSource
 import org.jetbrains.kotlin.gradle.plugin.internal.configurationTimePropertiesAccessor
@@ -150,3 +148,11 @@ internal val Project.localProperties: Provider<Map<String, String>>
  * Returns file collection [this] excluding files from [excludes] if not null
  */
 internal fun FileCollection.exclude(excludes: FileCollection?): FileCollection = if (excludes != null) minus(excludes) else this
+
+internal fun Project.fileCollectionFromConfigurableFileTree(fileTree: ConfigurableFileTree): ConfigurableFileCollection {
+    // It is important to pass exactly `fileTree.dir` as provider with explicit task dependency
+    // Because of the following bugs:
+    // * https://github.com/gradle/gradle/issues/27881 ConfigurableFileTree.from() doesn't preserve Task Dependencies
+    // * https://github.com/gradle/gradle/issues/27882 SourceDirectorySet doesn't accept ConfigurableFileTree
+    return project.filesProvider(fileTree) { fileTree.dir }
+}