Fix annotation processors outputting to classes dir with kapt 3

#KT-15915 fixed

 Annotation processor can access a classes directory provided by AP environment.
Previously kapt 3 was using kotlin-classes directory as a a classes directory.
However compileKotlin task does not expect this.
Also having multiple tasks with the same output dir is a bad practise in Gradle.

This change introduces a separate directory for classes generated by kapt 3.
Its output is copied to a resulting classes dir (just as a kotlin-classes dir).

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/Kapt3IT.kt

@@ -270,4 +270,26 @@ class Kapt3IT : BaseGradleIT() {
             assertCompiledKotlinSources(project.relativize(allMainKotlinSrc))
         }
     }
+
+    @Test
+    fun testKaptClassesDirSync() {
+        val project = Project("autoService", GRADLE_VERSION, directoryPrefix = "kapt2")
+
+        project.build("build") {
+            assertSuccessful()
+            assertKaptSuccessful()
+            assertFileExists("processor/build/classes/main/META-INF/services/javax.annotation.processing.Processor")
+            assertFileExists("processor/build/classes/main/processor/MyProcessor.class")
+        }
+
+        project.projectDir.getFileByName("MyProcessor.kt").modify {
+            it.replace("@AutoService(Processor::class)", "")
+        }
+
+        project.build(":processor:build") {
+            assertSuccessful()
+            assertNoSuchFile("processor/build/classes/main/META-INF/services/javax.annotation.processing.Processor")
+            assertFileExists("processor/build/classes/main/processor/MyProcessor.class")
+        }
+    }
 }

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kapt2/autoService/build.gradle

@@ -0,0 +1,25 @@
+buildscript {
+    repositories {
+        mavenLocal()
+        mavenCentral()
+    }
+    dependencies {
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+    }
+}
+
+apply plugin: 'kotlin-kapt'
+apply plugin: 'kotlin'
+
+allprojects {
+    repositories {
+        mavenLocal()
+        mavenCentral()
+    }
+}
+
+dependencies {
+    compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+    compile project(":processor")
+    kapt project(":processor")
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kapt2/autoService/processor/build.gradle

@@ -0,0 +1,9 @@
+apply plugin: 'kotlin-kapt'
+apply plugin: 'kotlin'
+
+dependencies {
+    ext.autoServiceVersion = '1.0-rc2'
+    compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+    compile "com.google.auto.service:auto-service:$autoServiceVersion"
+    kapt "com.google.auto.service:auto-service:$autoServiceVersion"
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kapt2/autoService/processor/src/main/kotlin/processor/MyProcessor.kt

@@ -0,0 +1,28 @@
+package processor
+
+import com.google.auto.service.AutoService
+import javax.annotation.processing.*
+import javax.lang.model.SourceVersion
+import javax.lang.model.element.TypeElement
+import javax.tools.Diagnostic
+
+@AutoService(Processor::class)
+@SupportedAnnotationTypes("annotation.ProcessThis")
+@SupportedSourceVersion(SourceVersion.RELEASE_8)
+class MyProcessor() : AbstractProcessor() {
+
+    private var fileCreated = false
+
+    override fun process(annotations: Set<TypeElement>,
+            roundEnv: RoundEnvironment): Boolean {
+        processingEnv.messager.printMessage(Diagnostic.Kind.NOTE, "Working!")
+        if (fileCreated) return true
+        fileCreated = true
+        val file = processingEnv.filer.createSourceFile("Check")
+        file.openWriter().use {
+            it.appendln("// $annotations")
+            it.appendln("public class Check {}")
+        }
+        return true
+    }
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kapt2/autoService/settings.gradle

@@ -0,0 +1 @@
+rootProject.name = 'kaptbug'

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kapt2/autoService/src/main/kotlin/annotation/ProcessThis.kt

@@ -0,0 +1,3 @@
+package annotation
+
+annotation class ProcessThis

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kapt2/autoService/src/main/kotlin/model/Model.kt

@@ -0,0 +1,17 @@
+package model
+
+import annotation.ProcessThis
+
+@ProcessThis
+interface Model {
+
+    var a: Int
+
+    var b: Int
+}
+
+@ProcessThis
+class Class {
+
+    var a = 0
+}

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/compilerRunner/GradleKotlinCompilerRunner.kt

@@ -60,12 +60,6 @@ internal class GradleCompilerRunner(private val project: Project) : KotlinCompil
     ): ExitCode {
         val outputDir = args.destinationAsFile
 
-        if (environment !is GradleIncrementalCompilerEnvironment) {
-            log.debug("Removing all kotlin classes in $outputDir")
-            // we're free to delete all classes since only we know about that directory
-            outputDir.deleteRecursively()
-        }
-
         val moduleFile = makeModuleFile(
                 args.moduleName,
                 isTest = false,

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/internal/Kapt3KotlinGradleSubplugin.kt

@@ -29,6 +29,7 @@ import org.gradle.api.tasks.compile.JavaCompile
 import org.jetbrains.kotlin.gradle.plugin.*
 import org.jetbrains.kotlin.gradle.plugin.android.AndroidGradleWrapper
 import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+import org.jetbrains.kotlin.gradle.tasks.SyncOutputTask
 import java.io.File
 
 // apply plugin: 'kotlin-kapt'
@@ -59,6 +60,9 @@ class Kapt3KotlinGradleSubplugin : KotlinGradleSubplugin<KotlinCompile> {
         }
 
         fun findMainKaptConfiguration(project: Project) = project.findKaptConfiguration(MAIN_KAPT_CONFIGURATION_NAME)
+
+        fun getKaptClasssesDir(project: Project, sourceSetName: String): File =
+                File(project.project.buildDir, "tmp/kapt3/classes/$sourceSetName")
     }
 
     private val kotlinToKaptTasksMap = mutableMapOf<KotlinCompile, KaptTask>()
@@ -156,7 +160,7 @@ class Kapt3KotlinGradleSubplugin : KotlinGradleSubplugin<KotlinCompile> {
         javaCompile.source(generatedFilesDir)
 
         pluginOptions += SubpluginOption("sources", generatedFilesDir.canonicalPath)
-        pluginOptions += SubpluginOption("classes", kotlinCompile.destinationDir.canonicalPath)
+        pluginOptions += SubpluginOption("classes", getKaptClasssesDir(project, sourceSetName).canonicalPath)
 
         val androidPlugin = variantData?.let {
             project.extensions.findByName("android") as? BaseExtension
@@ -193,6 +197,7 @@ class Kapt3KotlinGradleSubplugin : KotlinGradleSubplugin<KotlinCompile> {
 
     private fun Kapt3SubpluginContext.createKaptKotlinTask() {
         val sourcesOutputDir = getKaptGeneratedDir(project, sourceSetName)
+        val classesOutputDir = getKaptClasssesDir(project, sourceSetName)
 
         // Replace compile*Kotlin to kapt*Kotlin
         assert(kotlinCompile.name.startsWith("compile"))
@@ -207,6 +212,7 @@ class Kapt3KotlinGradleSubplugin : KotlinGradleSubplugin<KotlinCompile> {
 
         kaptTask.mapClasspath { kotlinCompile.classpath }
         kaptTask.destinationDir = sourcesOutputDir
+        kaptTask.classesDir = classesOutputDir
         kaptTask.dependsOn(*(javaCompile.dependsOn.filter { it !== kotlinCompile }.toTypedArray()))
         kotlinCompile.dependsOn(kaptTask)
 

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

@@ -39,12 +39,17 @@ open class KaptTask : AbstractCompile() {
         return FileUtil.isAncestor(destinationDir, this, /* strict = */ false)
     }
 
+    lateinit var classesDir: File
+
     @TaskAction
     override fun compile() {
         /** Delete everything inside the [destinationDir] */
         destinationDir.deleteRecursively()
         destinationDir.mkdirs()
 
+        classesDir.deleteRecursively()
+        classesDir.mkdirs()
+
         val sourceRoots = SourceRoots.ForJvm.create(getSource(), rawSourceRoots)
         val compileClasspath = classpath.toList().filter(File::exists)
 

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

@@ -21,15 +21,15 @@ import org.gradle.api.tasks.bundling.Zip
 import org.gradle.api.tasks.compile.AbstractCompile
 import org.gradle.api.tasks.compile.JavaCompile
 import org.jetbrains.kotlin.gradle.dsl.KotlinJvmOptionsImpl
-import org.jetbrains.kotlin.gradle.internal.AnnotationProcessingManager
-import org.jetbrains.kotlin.gradle.internal.Kapt3GradleSubplugin
-import org.jetbrains.kotlin.gradle.internal.Kapt3KotlinGradleSubplugin
-import org.jetbrains.kotlin.gradle.internal.initKapt
+import org.jetbrains.kotlin.gradle.internal.*
+import org.jetbrains.kotlin.gradle.internal.Kapt3KotlinGradleSubplugin.Companion.getKaptClasssesDir
 import org.jetbrains.kotlin.gradle.plugin.android.AndroidGradleWrapper
 import org.jetbrains.kotlin.gradle.plugin.android.KotlinJillTask
 import org.jetbrains.kotlin.gradle.tasks.*
 import org.jetbrains.kotlin.incremental.configureMultiProjectIncrementalCompilation
 import org.jetbrains.kotlin.incremental.multiproject.ArtifactDifferenceRegistryProviderAndroidWrapper
+import org.jetbrains.kotlin.utils.addToStdlib.firstIsInstance
+import org.jetbrains.kotlin.utils.addToStdlib.firstIsInstanceOrNull
 import java.io.File
 import java.net.URL
 import java.util.*
@@ -540,6 +540,7 @@ private fun createSyncOutputTask(
     syncTask.kotlinTask = kotlinCompile
     kotlinTask.javaOutputDir = javaDir
     kotlinAfterJavaTask?.javaOutputDir = javaDir
+    syncTask.kaptClassesDir = getKaptClasssesDir(project, variantName)
 
     // copying should be executed after a latter task
     val previousTask = kotlinAfterJavaTask ?: javaTask

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

@@ -16,6 +16,7 @@
 
 package org.jetbrains.kotlin.gradle.tasks
 
+import ch.qos.logback.core.util.FileUtil
 import org.gradle.api.DefaultTask
 import org.gradle.api.tasks.InputFiles
 import org.gradle.api.tasks.OutputDirectory
@@ -23,6 +24,7 @@ import org.gradle.api.tasks.OutputFiles
 import org.gradle.api.tasks.TaskAction
 import org.gradle.api.tasks.incremental.IncrementalTaskInputs
 import org.gradle.api.tasks.incremental.InputFileDetails
+import org.jetbrains.kotlin.com.intellij.openapi.util.io.FileUtil.*
 import org.jetbrains.kotlin.gradle.plugin.kotlinDebug
 import java.io.File
 import java.io.ObjectInputStream
@@ -55,6 +57,13 @@ import kotlin.properties.Delegates
 internal open class SyncOutputTask : DefaultTask() {
     @get:InputFiles
     var kotlinOutputDir: File by Delegates.notNull()
+
+    @get:InputFiles
+    var kaptClassesDir: File by Delegates.notNull()
+
+    private val classesDirs: List<File>
+            get() = listOf(kotlinOutputDir, kaptClassesDir).filter(File::exists)
+
     var javaOutputDir: File by Delegates.notNull()
     var kotlinTask: KotlinCompile by Delegates.notNull()
 
@@ -78,13 +87,14 @@ internal open class SyncOutputTask : DefaultTask() {
     @Suppress("unused")
     @TaskAction
     fun execute(inputs: IncrementalTaskInputs): Unit {
+        val sourceDirs = classesDirs.joinToString()
         if (inputs.isIncremental) {
-            logger.kotlinDebug { "Incremental copying files from $kotlinOutputDir to $javaOutputDir" }
+            logger.kotlinDebug { "Incremental copying files from $sourceDirs to $javaOutputDir" }
             inputs.outOfDate { processIncrementally(it) }
             inputs.removed { processIncrementally(it) }
         }
         else {
-            logger.kotlinDebug { "Non-incremental copying files from $kotlinOutputDir to $javaOutputDir" }
+            logger.kotlinDebug { "Non-incremental copying files from $sourceDirs to $javaOutputDir" }
             processNonIncrementally()
         }
 
@@ -103,14 +113,16 @@ internal open class SyncOutputTask : DefaultTask() {
         timestampsFile.delete()
         timestamps.clear()
 
-        kotlinOutputDir.walkTopDown().forEach {
-            copy(it, it.siblingInJavaDir)
+        for (dir in classesDirs) {
+            dir.walkTopDown().forEach {
+                copy(it, it.siblingInJavaDir(baseDir = dir))
+            }
         }
     }
 
     private fun processIncrementally(input: InputFileDetails) {
         val fileInKotlinDir = input.file
-        val fileInJavaDir = fileInKotlinDir.siblingInJavaDir
+        val fileInJavaDir = fileInKotlinDir.siblingInJavaDir()
 
         if (input.isRemoved) {
             // file was removed in kotlin dir, remove from java as well
@@ -146,8 +158,10 @@ internal open class SyncOutputTask : DefaultTask() {
         }
     }
 
-    private val File.siblingInJavaDir: File
-            get() = File(javaOutputDir, this.relativeTo(kotlinOutputDir).path)
+    private fun File.siblingInJavaDir(baseDir: File? = null): File {
+        val base = baseDir ?: classesDirs.find { isAncestor(it, this, true) }!!
+        return File(javaOutputDir, this.relativeTo(base).path)
+    }
 }
 
 private val TIMESTAMP_FILE_NAME = "kotlin-files-in-java-timestamps.bin"

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

@@ -231,6 +231,12 @@ open class KotlinCompile : AbstractKotlinCompile<K2JVMCompilerArguments>(), Kotl
             }
         }
 
+        if (!incremental) {
+            logger.kotlinDebug { "Removing all kotlin classes in $destinationDir" }
+            destinationDir.deleteRecursively()
+            destinationDir.mkdirs()
+        }
+
         try {
             val exitCode = compilerRunner.runJvmCompiler(sourceRoots.kotlinSourceFiles, sourceRoots.javaSourceRoots, args, environment)
             processCompilerExitCode(exitCode)