Support AGP's built-in Kotlin compilation

Previously, the sourceSet-specific KSP configurations (e.g., kspTest)
weren't being created when AGP's built-in Kotlin compilation was
enabled.

This change also increases the AGP version to 8.7.0 in order to test
against a version of AGP with the built-in Kotlin support.

This change also configures the AGP compatibility tests (AGP731IT and
AGP741IT) to run one test at a time to avoid race conditions seen when
the old AGP versions were trying to download SDKs simultaneously.

Bug: b/362279380
Test: GradleCompilationTest

gradle-plugin/src/main/kotlin/com/google/devtools/ksp/gradle/AndroidPluginIntegration.kt

@@ -53,7 +53,7 @@ object AndroidPluginIntegration {
     private fun decorateAndroidExtension(project: Project, onSourceSet: (String) -> Unit) {
         val sourceSets = when (val androidExt = project.extensions.getByName("android")) {
             is BaseExtension -> androidExt.sourceSets
-            is CommonExtension<*, *, *, *> -> androidExt.sourceSets
+            is CommonExtension<*, *, *, *, *, *> -> androidExt.sourceSets
             else -> throw RuntimeException("Unsupported Android Gradle plugin version.")
         }
         sourceSets.all {

gradle-plugin/src/main/kotlin/com/google/devtools/ksp/gradle/KspConfigurations.kt

@@ -35,11 +35,13 @@ class KspConfigurations(private val project: Project) {
         }.replaceFirstChar { it.lowercase() }
     }
 
+    /**
+     * Returns a new or existing [Configuration] with the given [name], with applied properties.
+     */
     private fun createConfiguration(
         name: String,
         readableSetName: String,
     ): Configuration {
-        // maybeCreate to be future-proof, but we should never have a duplicate with current logic
         return project.configurations.maybeCreate(name).apply {
             description = "KSP dependencies for the '$readableSetName' source set."
             isCanBeResolved = false // we'll resolve the processor classpath config
@@ -48,14 +50,19 @@ class KspConfigurations(private val project: Project) {
         }
     }
 
-    private fun getAndroidConfigurationName(target: KotlinTarget, sourceSet: String): String {
+    /**
+     * Returns the Android sourceSet-specific KSP configuration name given a [kotlinTarget] and [sourceSet].
+     *
+     * For single-platform, [kotlinTarget] can be null.
+     */
+    private fun getAndroidConfigurationName(kotlinTarget: KotlinTarget?, sourceSet: String): String {
         val isMain = sourceSet.endsWith("main", ignoreCase = true)
         val nameWithoutMain = when {
             isMain -> sourceSet.substring(0, sourceSet.length - 4)
             else -> sourceSet
         }
         // Note: on single-platform, target name is conveniently set to "".
-        return configurationNameOf(PREFIX, target.name, nameWithoutMain)
+        return configurationNameOf(PREFIX, kotlinTarget?.name ?: "", nameWithoutMain)
     }
 
     private fun getKotlinConfigurationName(compilation: KotlinCompilation<*>, sourceSet: KotlinSourceSet): String {
@@ -86,6 +93,13 @@ class KspConfigurations(private val project: Project) {
             // 1.6.0: decorateKotlinProject(project.kotlinExtension)?
             decorateKotlinProject(project.extensions.getByName("kotlin") as KotlinProjectExtension, project)
         }
+        // Create sourceSet-specific KSP configurations for the case when the KotlinBaseApiPlugin is applied instead
+        // of the KotlinBasePluginWrapper (e.g., when AGP's built-in Kotlin support is enabled).
+        project.plugins.withType(KotlinBaseApiPlugin::class.java) {
+            // FIXME: After KT-70897 is fixed and AGP's built-in Kotlin support adds a `kotlin` extension, call
+            //  decorateKotlinProject here instead.
+            createAndroidSourceSetConfigurations(project, kotlinTarget = null)
+        }
     }
 
     private fun decorateKotlinProject(kotlin: KotlinProjectExtension, project: Project) {
@@ -125,12 +139,7 @@ class KspConfigurations(private val project: Project) {
      */
     private fun decorateKotlinTarget(target: KotlinTarget) {
         if (target.platformType == KotlinPlatformType.androidJvm) {
-            AndroidPluginIntegration.forEachAndroidSourceSet(target.project) { sourceSet ->
-                createConfiguration(
-                    name = getAndroidConfigurationName(target, sourceSet),
-                    readableSetName = "$sourceSet (Android)"
-                )
-            }
+            createAndroidSourceSetConfigurations(target.project, target)
         } else {
             target.compilations.configureEach { compilation ->
                 compilation.kotlinSourceSetsObservable.forAll { sourceSet ->
@@ -177,4 +186,18 @@ class KspConfigurations(private val project: Project) {
             compilation.target.project.configurations.findByName(it)
         }.toSet()
     }
+
+    /**
+     * Creates the Android sourceSet-specific KSP configurations for the given [project] and [kotlinTarget]
+     *
+     * For single-platform, [kotlinTarget] can be null.
+     */
+    private fun createAndroidSourceSetConfigurations(project: Project, kotlinTarget: KotlinTarget?) {
+        AndroidPluginIntegration.forEachAndroidSourceSet(project) { sourceSet ->
+            createConfiguration(
+                name = getAndroidConfigurationName(kotlinTarget, sourceSet),
+                readableSetName = "$sourceSet (Android)"
+            )
+        }
+    }
 }

gradle-plugin/src/test/kotlin/com/google/devtools/ksp/gradle/GradleCompilationTest.kt

@@ -399,4 +399,19 @@ class GradleCompilationTest {
 
         testRule.runner().withArguments().build()
     }
+
+    /**
+     * Regression test for b/362279380
+     */
+    @Test
+    fun androidGradlePluginBuiltInKotlin() {
+        testRule.setupAppAsAndroidApp(enableAgpBuiltInKotlinSupport = true)
+        testRule.appModule.dependencies.addAll(
+            listOf(
+                artifact(configuration = "ksp", "androidx.room:room-compiler:2.4.2"),
+                artifact(configuration = "kspTest", "androidx.room:room-compiler:2.4.2")
+            )
+        )
+        testRule.runner().withArguments(":app:assembleDebug").build()
+    }
 }

gradle-plugin/src/test/kotlin/com/google/devtools/ksp/gradle/testing/KspIntegrationTestRule.kt

@@ -92,16 +92,23 @@ class KspIntegrationTestRule(
 
     /**
      * Sets up the app module as an android app, adding necessary plugin dependencies, a manifest
-     * file and necessary gradle configuration.
+     * file and necessary gradle configuration. If [enableAgpBuiltInKotlinSupport] is true, enable AGP's built-in Kotlin
+     * support instead of applying the Kotlin Android Gradle plugin.
      */
-    fun setupAppAsAndroidApp() {
+    fun setupAppAsAndroidApp(enableAgpBuiltInKotlinSupport: Boolean = false) {
         testProject.appModule.plugins.addAll(
             listOf(
                 PluginDeclaration.id("com.android.application", testConfig.androidBaseVersion),
-                PluginDeclaration.kotlin("android", testConfig.kotlinBaseVersion),
                 PluginDeclaration.id("com.google.devtools.ksp", testConfig.kspVersion)
             )
         )
+        if (enableAgpBuiltInKotlinSupport) {
+            testProject.appModule
+                .plugins
+                .add(PluginDeclaration.id("com.android.experimental.built-in-kotlin", testConfig.androidBaseVersion))
+        } else {
+            testProject.appModule.plugins.add(PluginDeclaration.kotlin("android", testConfig.kotlinBaseVersion))
+        }
         addAndroidBoilerplate()
     }
 
@@ -126,11 +133,15 @@ class KspIntegrationTestRule(
             """
             android {
                 namespace = "com.example.kspandroidtestapp"
-                compileSdkVersion(31)
+                compileSdk = 31
                 defaultConfig {
-                    minSdkVersion(24)
+                    minSdk = 24
                 }
             }
+            
+            dependencies {
+                implementation("org.jetbrains.kotlin:kotlin-stdlib:${testConfig.kotlinBaseVersion}")
+            }
             """.trimIndent()
         )
         testProject.appModule.moduleRoot.resolve("src/main/AndroidManifest.xml")

gradle.properties

@@ -2,7 +2,7 @@
 org.gradle.jvmargs=-Duser.country=US -Dkotlin.daemon.jvm.options=-Xmx4096m -Dfile.encoding=UTF-8
 
 kotlinBaseVersion=2.1.0-dev-5441
-agpBaseVersion=8.0.2
+agpBaseVersion=8.7.0
 intellijVersion=233.13135.103
 junitVersion=4.13.1
 junit5Version=5.8.2

integration-tests/build.gradle.kts

@@ -20,8 +20,7 @@ dependencies {
     testImplementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.6.3")
 }
 
-tasks.withType<Test> {
-    maxParallelForks = max(1, Runtime.getRuntime().availableProcessors() / 2)
+fun Test.configureCommonSettings() {
     systemProperty("kotlinVersion", kotlinBaseVersion)
     systemProperty("kspVersion", version)
     systemProperty("agpVersion", agpBaseVersion)
@@ -38,3 +37,33 @@ tasks.withType<Test> {
     dependsOn(":symbol-processing-cmdline:publishAllPublicationsToTestRepository")
     dependsOn(":symbol-processing-aa-embeddable:publishAllPublicationsToTestRepository")
 }
+
+val agpCompatibilityTestClasses = listOf("**/AGP731IT.class", "**/AGP741IT.class")
+
+// Create a new test task for the AGP compatibility tests
+val agpCompatibilityTest by tasks.registering(Test::class) {
+    description = "Runs AGP compatibility tests with maxParallelForks = 1"
+    group = "verification"
+
+    // Include only the AGP compatibility tests
+    include(agpCompatibilityTestClasses)
+
+    // Set maxParallelForks to 1 to avoid race conditions when downloading SDKs with old AGPs
+    maxParallelForks = 1
+
+    // Apply common settings
+    configureCommonSettings()
+}
+
+tasks.named<Test>("test") {
+    maxParallelForks = max(1, Runtime.getRuntime().availableProcessors() / 2)
+
+    // Exclude test classes from agpCompatibilityTest
+    exclude(agpCompatibilityTestClasses)
+
+    // Apply common settings
+    configureCommonSettings()
+
+    // Ensure that 'test' depends on 'compatibilityTest'
+    dependsOn(agpCompatibilityTest)
+}

integration-tests/src/test/resources/android-view-binding/app/build.gradle.kts

@@ -12,7 +12,7 @@ dependencies {
 android {
     namespace = "com.example.kspandroidtestapp"
     defaultConfig {
-        minSdkVersion(24)
+        minSdk = 24
     }
     compileSdk = 34
     buildFeatures { 

integration-tests/src/test/resources/playground-android-multi/application/build.gradle.kts

@@ -20,11 +20,11 @@ dependencies {
 
 android {
     namespace = "com.example.myapplication"
-    compileSdkVersion(34)
+    compileSdk = 34
     defaultConfig {
         applicationId = "org.gradle.kotlin.dsl.samples.androidstudio"
-        minSdkVersion(34)
-        targetSdkVersion(34)
+        minSdk = 34
+        targetSdk = 34
         versionCode = 1
         versionName = "1.0"
     }

integration-tests/src/test/resources/playground-android-multi/workload/build.gradle.kts

@@ -23,10 +23,10 @@ dependencies {
 
 android {
     namespace = "com.example.mylibrary"
-    compileSdkVersion(34)
+    compileSdk = 34
     defaultConfig {
-        minSdkVersion(34)
-        targetSdkVersion(34)
+        minSdk = 34
+        targetSdk = 34
     }
 }
 

integration-tests/src/test/resources/playground-android/workload/build.gradle.kts

@@ -23,11 +23,11 @@ dependencies {
 
 android {
     namespace = "com.example.myapplication"
-    compileSdkVersion(34)
+    compileSdk = 34
     defaultConfig {
         applicationId = "org.gradle.kotlin.dsl.samples.androidstudio"
-        minSdkVersion(34)
-        targetSdkVersion(34)
+        minSdk = 34
+        targetSdk = 34
         versionCode = 1
         versionName = "1.0"
     }