Enable kotlin java toolchain support for kapt task.

With this change 'KaptWithoutKotlincTask' will also support overriding
default Gradle JDK to run kapt. In such case only 'in-process' kapt
 worker isolation mode is supported.

If user does not provide custom JDK, kapt worker isolation mode will
be 'no-isolation' as before.

^KT-45611 In Progress

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

@@ -11,6 +11,7 @@ import org.gradle.testkit.runner.BuildResult
 import org.gradle.util.GradleVersion
 import org.jetbrains.kotlin.gradle.testbase.*
 import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Test
 import java.io.File
 
 class KotlinJavaToolchainTest : KGPBaseTest() {
@@ -106,6 +107,112 @@ class KotlinJavaToolchainTest : KGPBaseTest() {
         }
     }
 
+    @DisplayName("Kapt task should use only process worker isolation when kotlin java toolchain is set")
+    @GradleTest
+    internal fun kaptTasksShouldUseProcessWorkersIsolation(gradleVersion: GradleVersion) {
+        project(
+            projectName = "simpleWithKapt".fullProjectName,
+            gradleVersion = gradleVersion,
+        ) {
+            useJdk9ToCompile()
+            gradleProperties.append(
+                "kapt.workers.isolation = none"
+            )
+
+            build("assemble") {
+                assertDaemonIsUsingJdk(getJdk9().javaExecutableRealPath)
+
+                assertOutputContains("Using workers PROCESS isolation mode to run kapt")
+                assertOutputContains("Using non-default Kotlin java toolchain - 'kapt.workers.isolation == none' property is ignored!")
+            }
+        }
+    }
+
+    @DisplayName("Kapt task should use worker no-isolation mode when build is using Gradle JDK")
+    @GradleTest
+    internal fun kaptTasksShouldUseNoIsolationModeOnDefaultJvm(gradleVersion: GradleVersion) {
+        project(
+            projectName = "simpleWithKapt".fullProjectName,
+            gradleVersion = gradleVersion,
+        ) {
+            build("assemble") {
+                assertOutputContains("Using workers NONE isolation mode to run kapt")
+                assertOutputDoesNotContain("Using non-default Kotlin java toolchain - 'kapt.workers.isolation == none' property is ignored!")
+            }
+        }
+    }
+
+    @DisplayName("Kapt tasks with custom JDK should be cacheable")
+    @GradleTest
+    internal fun kaptTasksWithCustomJdkCacheable(gradleVersion: GradleVersion) {
+        val buildCache = workingDir.resolve("custom-jdk-build-cache")
+        project(
+            projectName = "simpleWithKapt".fullProjectName,
+            gradleVersion = gradleVersion,
+            projectPathAdditionalSuffix = "1/cache-test",
+            buildOptions = defaultBuildOptions.copy(buildCacheEnabled = true)
+        ) {
+            enableLocalBuildCache(buildCache)
+            useJdk9ToCompile()
+
+            build("assemble")
+        }
+
+        project(
+            projectName = "simpleWithKapt".fullProjectName,
+            gradleVersion = gradleVersion,
+            projectPathAdditionalSuffix = "2/cache-test",
+            buildOptions = defaultBuildOptions.copy(buildCacheEnabled = true),
+        ) {
+            enableLocalBuildCache(buildCache)
+            useJdk9ToCompile()
+
+            build("assemble") {
+                assertTasksFromCache(
+                    ":kaptGenerateStubsKotlin",
+                    ":kaptKotlin",
+                    ":compileKotlin"
+                )
+            }
+        }
+    }
+
+    @DisplayName("Kapt tasks with default JDK and different isolation modes should be cacheable")
+    @GradleTest
+    internal fun kaptCacheableOnSwitchingIsolationModeAndDefaultJDK(gradleVersion: GradleVersion) {
+        val buildCache = workingDir.resolve("custom-jdk-build-cache")
+        project(
+            projectName = "simpleWithKapt".fullProjectName,
+            gradleVersion = gradleVersion,
+            projectPathAdditionalSuffix = "1/cache-test",
+            buildOptions = defaultBuildOptions.copy(buildCacheEnabled = true)
+        ) {
+            enableLocalBuildCache(buildCache)
+
+            build("assemble")
+        }
+
+        project(
+            projectName = "simpleWithKapt".fullProjectName,
+            gradleVersion = gradleVersion,
+            projectPathAdditionalSuffix = "2/cache-test",
+            buildOptions = defaultBuildOptions.copy(buildCacheEnabled = true),
+        ) {
+            enableLocalBuildCache(buildCache)
+            gradleProperties.append(
+                "kapt.workers.isolation = process"
+            )
+
+            build("assemble") {
+                assertTasksFromCache(
+                    ":kaptGenerateStubsKotlin",
+                    ":kaptKotlin",
+                    ":compileKotlin"
+                )
+            }
+        }
+    }
+
     private fun BuildResult.assertDaemonIsUsingJdk(
         javaexecPath: String
     ) = assertOutputContains("i: connected to the daemon. Daemon is using following 'java' executable to run itself: $javaexecPath")

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

@@ -18,6 +18,7 @@ internal val DEFAULT_GROOVY_SETTINGS_FILE =
 
         plugins {
             id "org.jetbrains.kotlin.jvm" version "${'$'}kotlin_version"
+            id "org.jetbrains.kotlin.kapt" version "${'$'}kotlin_version"
         }
     }
     """.trimIndent()

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlin-java-toolchain/simpleWithKapt/build.gradle

@@ -0,0 +1,18 @@
+plugins {
+    id "org.jetbrains.kotlin.jvm"
+    id "org.jetbrains.kotlin.kapt"
+    id "java"
+}
+
+repositories {
+    mavenLocal()
+    mavenCentral()
+}
+
+dependencies {
+    implementation "org.jetbrains.kotlin:annotation-processor-example:$kotlin_version"
+    kapt "org.jetbrains.kotlin:annotation-processor-example:$kotlin_version"
+    testImplementation 'junit:junit:4.12'
+}
+
+compileKotlin.kotlinOptions.allWarningsAsErrors = true

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlin-java-toolchain/simpleWithKapt/gradle.properties

@@ -0,0 +1 @@
+kapt.verbose=true

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlin-java-toolchain/simpleWithKapt/src/main/java/foo/InternalDummy.kt

@@ -0,0 +1,5 @@
+package foo
+
+internal class InternalDummy {
+    internal val x = "InternalDummy.x"
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlin-java-toolchain/simpleWithKapt/src/main/java/foo/InternalDummyUser.kt

@@ -0,0 +1,7 @@
+package foo
+
+internal class InternalDummyUser {
+    internal fun use(dummy: InternalDummy) {
+        if (dummy.x != "InternalDummy.x") throw AssertionError("dummy.x = ${dummy.x}")
+    }
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlin-java-toolchain/simpleWithKapt/src/main/java/foo/topLevelDummyFun.kt

@@ -0,0 +1,3 @@
+package foo
+
+fun topLevelDummyFun() {}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlin-java-toolchain/simpleWithKapt/src/main/java/javaPackage/JavaClass.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2010-2015 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package javaPackage;
+
+public class JavaClass {
+
+    public void test() {
+        System.out.println(example.TestClassGenerated.class.getName());
+        System.out.println(example.SourceAnnotatedTestClassGenerated.class.getName());
+        System.out.println(example.BinaryAnnotatedTestClassGenerated.class.getName());
+        System.out.println(example.RuntimeAnnotatedTestClassGenerated.class.getName());
+    }
+
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlin-java-toolchain/simpleWithKapt/src/main/java/test.kt

@@ -0,0 +1,15 @@
+package example
+
+@example.ExampleAnnotation
+@example.ExampleSourceAnnotation
+@example.ExampleBinaryAnnotation
+@example.ExampleRuntimeAnnotation
+public class TestClass {
+
+    @example.ExampleAnnotation
+    public val testVal: String = "text"
+
+    @example.ExampleAnnotation
+    public fun testFunction(): TestClassGenerated = TestClassGenerated()
+
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlin-java-toolchain/simpleWithKapt/src/test/java/example/JavaTest.java

@@ -0,0 +1,12 @@
+package example;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class JavaTest {
+    @Test
+    public void test() {
+        TestClass testClass = new TestClass();
+        Assert.assertEquals("text", testClass.getTestVal());
+    }
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlin-java-toolchain/simpleWithKapt/src/test/java/foo/InternalDummyTest.kt

@@ -0,0 +1,12 @@
+package foo
+
+import org.junit.Test
+
+class InternalDummyTest {
+    @Test
+    fun testDummy() {
+        val dummy = InternalDummy()
+        val dummyUser = InternalDummyUser()
+        dummyUser.use(dummy)
+    }
+}

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/internal/kapt/KaptTask.kt

@@ -4,9 +4,11 @@ import org.gradle.api.file.ConfigurableFileCollection
 import org.gradle.api.file.DirectoryProperty
 import org.gradle.api.file.FileCollection
 import org.gradle.api.internal.ConventionTask
+import org.gradle.api.model.ObjectFactory
 import org.gradle.api.provider.ListProperty
 import org.gradle.api.provider.Property
 import org.gradle.api.provider.ProviderFactory
+import org.gradle.api.provider.Provider
 import org.gradle.api.tasks.*
 import org.gradle.api.tasks.incremental.IncrementalTaskInputs
 import org.jetbrains.kotlin.build.report.metrics.BuildMetricsReporter
@@ -17,10 +19,11 @@ import org.jetbrains.kotlin.gradle.internal.kapt.incremental.KaptIncrementalChan
 import org.jetbrains.kotlin.gradle.internal.kapt.incremental.UnknownSnapshot
 import org.jetbrains.kotlin.gradle.internal.tasks.TaskConfigurator
 import org.jetbrains.kotlin.gradle.internal.tasks.TaskWithLocalState
-import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+import org.jetbrains.kotlin.gradle.tasks.*
 import org.jetbrains.kotlin.gradle.tasks.cacheOnlyIfEnabledForKotlin
 import org.jetbrains.kotlin.gradle.tasks.clearLocalState
 import org.jetbrains.kotlin.gradle.utils.getValue
+import org.jetbrains.kotlin.gradle.utils.propertyWithNewInstance
 import java.io.File
 import java.util.concurrent.Callable
 import java.util.jar.JarFile
@@ -28,9 +31,10 @@ import javax.inject.Inject
 
 @CacheableTask
 abstract class KaptTask @Inject constructor(
-    @get:Internal
-    protected val providerFactory: ProviderFactory
-): ConventionTask(), TaskWithLocalState {
+    objectFactory: ObjectFactory
+) : ConventionTask(),
+    TaskWithLocalState,
+    UsesKotlinJavaToolchain {
 
     open class Configurator<T: KaptTask>(protected val kotlinCompileTask: KotlinCompile) : TaskConfigurator<T> {
         override fun configure(task: T) {
@@ -117,6 +121,9 @@ abstract class KaptTask @Inject constructor(
     @get:Internal
     abstract val classpath: ConfigurableFileCollection
 
+    final override val kotlinJavaToolchainProvider: Provider<KotlinJavaToolchainProvider> =
+        objectFactory.propertyWithNewInstance()
+
     @Suppress("unused", "DeprecatedCallableAddReplaceWith")
     @Deprecated(
         message = "Don't use directly. Used only for up-to-date checks",

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/internal/kapt/KaptWithKotlincTask.kt

@@ -8,7 +8,6 @@ package org.jetbrains.kotlin.gradle.internal
 import org.gradle.api.file.ConfigurableFileCollection
 import org.gradle.api.model.ObjectFactory
 import org.gradle.api.provider.Property
-import org.gradle.api.provider.ProviderFactory
 import org.gradle.api.provider.Provider
 import org.gradle.api.tasks.*
 import org.gradle.api.tasks.incremental.IncrementalTaskInputs
@@ -22,17 +21,14 @@ import org.jetbrains.kotlin.gradle.logging.GradleKotlinLogger
 import org.jetbrains.kotlin.gradle.logging.GradlePrintingMessageCollector
 import org.jetbrains.kotlin.gradle.report.ReportingSettings
 import org.jetbrains.kotlin.gradle.tasks.*
-import org.jetbrains.kotlin.gradle.utils.*
 import org.jetbrains.kotlin.gradle.utils.toSortedPathsArray
 import java.io.File
 import javax.inject.Inject
 
 abstract class KaptWithKotlincTask @Inject constructor(
-    objectFactory: ObjectFactory,
-    providerFactory: ProviderFactory
-) : KaptTask(providerFactory),
-    CompilerArgumentAwareWithInput<K2JVMCompilerArguments>,
-    UsesKotlinJavaToolchain{
+    objectFactory: ObjectFactory
+) : KaptTask(objectFactory),
+    CompilerArgumentAwareWithInput<K2JVMCompilerArguments> {
 
     class Configurator(kotlinCompileTask: KotlinCompile): KaptTask.Configurator<KaptWithKotlincTask>(kotlinCompileTask) {
         override fun configure(task: KaptWithKotlincTask) {
@@ -56,9 +52,6 @@ abstract class KaptWithKotlincTask @Inject constructor(
     @get:Internal
     val taskProvider by lazy { GradleCompileTaskProvider(this) }
 
-    final override val kotlinJavaToolchainProvider: Provider<KotlinJavaToolchainProvider> =
-        objectFactory.propertyWithNewInstance()
-
     override fun createCompilerArgs(): K2JVMCompilerArguments = K2JVMCompilerArguments()
 
     @get:Internal

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/internal/kapt/KaptWithoutKotlincTask.kt

@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.gradle.internal
 
 import org.gradle.api.file.ConfigurableFileCollection
+import org.gradle.api.model.ObjectFactory
 import org.gradle.api.provider.Property
 import org.gradle.api.provider.ProviderFactory
 import org.gradle.api.tasks.*
@@ -23,7 +24,6 @@ import org.jetbrains.kotlin.gradle.plugin.KotlinAndroidPluginWrapper
 import org.jetbrains.kotlin.gradle.tasks.CompilerPluginOptions
 import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 import org.jetbrains.kotlin.gradle.tasks.findKotlinStdlibClasspath
-import org.jetbrains.kotlin.gradle.tasks.findToolsJar
 import org.jetbrains.kotlin.gradle.utils.isGradleVersionAtLeast
 import org.jetbrains.kotlin.utils.PathUtil
 import org.slf4j.LoggerFactory
@@ -34,9 +34,10 @@ import java.net.URLClassLoader
 import javax.inject.Inject
 
 abstract class KaptWithoutKotlincTask @Inject constructor(
-    providerFactory: ProviderFactory,
+    objectFactory: ObjectFactory,
+    private val providerFactory: ProviderFactory,
     private val workerExecutor: WorkerExecutor
-) : KaptTask(providerFactory) {
+) : KaptTask(objectFactory) {
 
     class Configurator(kotlinCompileTask: KotlinCompile): KaptTask.Configurator<KaptWithoutKotlincTask>(kotlinCompileTask) {
         override fun configure(task: KaptWithoutKotlincTask) {
@@ -157,15 +158,9 @@ abstract class KaptWithoutKotlincTask @Inject constructor(
         }
 
         val kaptClasspath = kaptJars.toList() + kotlinStdlibClasspath
-
-        //TODO for gradle < 6.5
-        val isolationModeStr = getValue("kapt.workers.isolation") ?: "none"
-        val isolationMode = when (isolationModeStr.toLowerCase()) {
-            "process" -> IsolationMode.PROCESS
-            "none" -> IsolationMode.NONE
-            else -> IsolationMode.NONE
-        }
-        val toolsJarURLSpec = findToolsJar()?.toURI()?.toURL()?.toString().orEmpty()
+        val isolationMode = getWorkerIsolationMode()
+        logger.info("Using workers $isolationMode isolation mode to run kapt")
+        val toolsJarURLSpec = kotlinJavaToolchainProvider.get().jdkToolsJar.orNull?.toURI()?.toURL()?.toString().orEmpty()
 
         submitWork(
             isolationMode,
@@ -175,6 +170,25 @@ abstract class KaptWithoutKotlincTask @Inject constructor(
         )
     }
 
+    private fun getWorkerIsolationMode(): IsolationMode {
+        val kotlinJavaToolchain = kotlinJavaToolchainProvider.get()
+        val gradleJvm = kotlinJavaToolchain.currentJvm.get()
+        // Ensuring Gradle build JDK is set to kotlin toolchain by also comparing javaExecutable paths,
+        // as user may set JDK with same major Java version, but from different vendor
+        val isRunningOnGradleJvm = gradleJvm.javaVersion == kotlinJavaToolchain.javaVersion.get() &&
+                gradleJvm.javaExecutable.absolutePath == kotlinJavaToolchain.javaExecutable.get().asFile.absolutePath
+        val isolationModeStr = getValue("kapt.workers.isolation")?.toLowerCase()
+        return when {
+            (isolationModeStr == null || isolationModeStr == "none") && isRunningOnGradleJvm -> IsolationMode.NONE
+            else -> {
+                if (isolationModeStr == "none") {
+                    logger.warn("Using non-default Kotlin java toolchain - 'kapt.workers.isolation == none' property is ignored!")
+                }
+                IsolationMode.PROCESS
+            }
+        }
+    }
+
     private fun submitWork(
         isolationMode: IsolationMode,
         optionsForWorker: KaptOptionsForWorker,
@@ -187,14 +201,13 @@ abstract class KaptWithoutKotlincTask @Inject constructor(
                     // for tests
                     it.forkOptions.jvmArgs("-verbose:class")
                 }
-                logger.info("Kapt worker classpath: ${it.classpath}")
-            }
-            IsolationMode.CLASSLOADER -> workerExecutor.classLoaderIsolation() {
+                it.forkOptions.executable = kotlinJavaToolchainProvider.get().javaExecutable.asFile.get().absolutePath
                 logger.info("Kapt worker classpath: ${it.classpath}")
             }
             IsolationMode.NONE -> workerExecutor.noIsolation()
-            IsolationMode.AUTO -> throw UnsupportedOperationException(
-                "Kapt worker compilation does not support $isolationMode"
+            IsolationMode.AUTO, IsolationMode.CLASSLOADER -> throw UnsupportedOperationException(
+                "Kapt worker compilation does not support class loader isolation. " +
+                        "Please use either \"none\" or \"process\" in gradle.properties."
             )
         }
 

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/tasks/KotlinJavaToolchainProvider.kt

@@ -24,7 +24,8 @@ abstract class KotlinJavaToolchainProvider @Inject constructor(
     objects: ObjectFactory,
     files: ProjectLayout
 ) : KotlinJavaToolchain {
-    private val currentJvm: Property<Jvm> = objects
+    @get:Internal
+    internal val currentJvm: Property<Jvm> = objects
         .property<Jvm>(Jvm.current())
         .chainedFinalizeValueOnRead()
 

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/tasks/jarSearchingUtil.kt

@@ -16,7 +16,6 @@
 
 package org.jetbrains.kotlin.gradle.tasks
 
-import org.gradle.api.GradleException
 import org.gradle.api.Project
 import org.gradle.api.artifacts.Configuration
 import org.gradle.api.artifacts.ResolvedDependency
@@ -104,21 +103,6 @@ internal fun findKotlinScriptRuntimeClasspath(project: Project): List<File> =
 internal fun findKotlinReflectClasspath(project: Project): List<File> =
     findKotlinModuleJar(project, KOTLIN_REFLECT_EXPECTED_CLASS, KOTLIN_REFLECT)
 
-internal fun findToolsJar(): File? {
-    val javacUtilContextClass =
-        try {
-            Class.forName("com.sun.tools.javac.util.Context")
-        } catch (classNotFound: ClassNotFoundException) {
-            val javaHome = System.getProperty("java.home") // current Java installation path
-            throw GradleException(
-                "Kotlin could not find the required JDK tools in the Java installation ${javaHome?.let { "'$it' " }.orEmpty()}" +
-                        "used by Gradle. Make sure Gradle is running on a JDK, not JRE.",
-                classNotFound
-            )
-        }
-    return javacUtilContextClass?.let(::findJarByClass)
-}
-
 internal fun findJarByClass(klass: Class<*>): File? {
     val classFileName = klass.name.substringAfterLast(".") + ".class"
     val resource = klass.getResource(classFileName) ?: return null