Kapt: Do not use AbstractCompile as a supertype for KaptTask (KT-19179)

Gradle sometimes tells that kaptCompile is UP-TO-DATE even when it's not true, so the annotation processing step is silently skipped.
Looks like replacing `mapSource {}` with an explicit getter or with manual `source()` invocation does not fix the problem.

This looks like a bug in Gradle appeared since 3.0. The test from this commit works with Gradle 2.14.1.

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

@@ -1,8 +1,10 @@
 package org.jetbrains.kotlin.gradle
 
+import org.jetbrains.kotlin.gradle.util.getFileByName
 import org.jetbrains.kotlin.gradle.util.modify
 import org.junit.Test
 import java.io.File
+import java.util.zip.ZipFile
 
 class KotlinGradlePluginMultiVersionIT : BaseMultiGradleVersionIT() {
     @Test
@@ -18,6 +20,48 @@ class KotlinGradlePluginMultiVersionIT : BaseMultiGradleVersionIT() {
         }
     }
 
+    @Test
+    fun testKt19179() {
+        val project = Project("kt19179", gradleVersion, directoryPrefix = "kapt2")
+
+        project.build("build") {
+            assertSuccessful()
+            assertFileExists("processor/build/tmp/kapt3/classes/main/META-INF/services/javax.annotation.processing.Processor")
+
+            val processorJar = fileInWorkingDir("processor/build/libs/processor.jar")
+            assert(processorJar.exists())
+
+            ZipFile(processorJar).use { zip ->
+                assert(zip.getEntry("META-INF/services/javax.annotation.processing.Processor") != null)
+            }
+
+            assertTasksExecuted(listOf(
+                    ":processor:kaptGenerateStubsKotlin", ":processor:kaptKotlin",
+                    ":app:kaptGenerateStubsKotlin", ":app:kaptKotlin"))
+        }
+
+        project.projectDir.getFileByName("Test.kt").modify { text ->
+            assert("SomeClass()" in text)
+            text.replace("SomeClass()", "SomeClass(); val a = 5")
+        }
+
+        project.build("build") {
+            assertSuccessful()
+            assertTasksUpToDate(listOf(":processor:kaptGenerateStubsKotlin", ":processor:kaptKotlin", ":app:kaptKotlin"))
+            assertTasksExecuted(listOf(":app:kaptGenerateStubsKotlin"))
+        }
+
+        project.projectDir.getFileByName("Test.kt").modify { text ->
+            text + "\n\nfun t() {}"
+        }
+
+        project.build("build") {
+            assertSuccessful()
+            assertTasksUpToDate(listOf(":processor:kaptGenerateStubsKotlin", ":processor:kaptKotlin"))
+            assertTasksExecuted(listOf(":app:kaptGenerateStubsKotlin", ":app:kaptKotlin"))
+        }
+    }
+
     @Test
     fun testJavaIcCompatibility() {
         val version = gradleVersion.split(".").map(String::toInt)

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kapt2/kt19179/api/build.gradle

@@ -0,0 +1,5 @@
+apply plugin: 'kotlin'
+
+dependencies {
+    compile "org.jetbrains.kotlin:kotlin-runtime:$kotlin_version"
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kapt2/kt19179/api/src/main/kotlin/Api.kt

@@ -0,0 +1,6 @@
+package com.example
+
+import kotlin.annotation.AnnotationTarget.CLASS
+
+@Target(CLASS)
+annotation class SomeAnnotation

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kapt2/kt19179/app/build.gradle

@@ -0,0 +1,8 @@
+apply plugin: 'kotlin'
+apply plugin: 'kotlin-kapt'
+
+dependencies {
+    compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+    compile project(':api')
+    kapt project(':processor')
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kapt2/kt19179/app/src/main/kotlin/Test.kt

@@ -0,0 +1,7 @@
+package com.example
+
+@SomeAnnotation class SomeClass
+
+fun main(vararg args: String) {
+    SomeClass()
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kapt2/kt19179/build.gradle

@@ -0,0 +1,20 @@
+buildscript {
+    repositories {
+        mavenLocal()
+    }
+
+    dependencies {
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+    }
+}
+
+subprojects {
+    repositories {
+        mavenLocal()
+        jcenter()
+    }
+}
+
+task clean(type: Delete) {
+    delete rootProject.buildDir
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kapt2/kt19179/processor/build.gradle

@@ -0,0 +1,9 @@
+apply plugin: 'kotlin'
+apply plugin: 'kotlin-kapt'
+
+dependencies {
+    compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+    compile 'com.google.auto.service:auto-service:1.0-rc3'
+    kapt 'com.google.auto.service:auto-service:1.0-rc3'
+    compile project(':api')
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kapt2/kt19179/processor/src/main/kotlin/Processor.kt

@@ -0,0 +1,19 @@
+package com.example
+
+import com.google.auto.service.AutoService
+import javax.annotation.processing.AbstractProcessor
+import javax.annotation.processing.Processor
+import javax.annotation.processing.RoundEnvironment
+import javax.lang.model.element.TypeElement
+import javax.tools.Diagnostic.Kind.MANDATORY_WARNING
+
+@AutoService(Processor::class)
+class Processor : AbstractProcessor() {
+
+    override fun getSupportedAnnotationTypes() = setOf(SomeAnnotation::class.java.canonicalName)
+
+    override fun process(annotations: Set<TypeElement>, roundEnv: RoundEnvironment): Boolean {
+        processingEnv.messager.printMessage(MANDATORY_WARNING, "*** AP RUNNING ***' ")
+        return true
+    }
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kapt2/kt19179/settings.gradle

@@ -0,0 +1,4 @@
+rootProject.name = 'kapt3-issues'
+include ':app'
+include ':api'
+include ':processor'

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

@@ -281,19 +281,8 @@ class Kapt3KotlinGradleSubplugin : KotlinGradleSubplugin<KotlinCompile> {
 
         kaptTask.stubsDir = getKaptStubsDir()
         kaptTask.destinationDir = sourcesOutputDir
-        kaptTask.mapClasspath { kotlinCompile.classpath }
         kaptTask.classesDir = classesOutputDir
 
-        kaptTask.mapSource {
-            val sourcesFromKotlinTask = kotlinCompile.source
-                    .filter { it.extension == "java" && !kaptTask.isInsideDestinationDirs(it) }
-                    .asFileTree
-
-            val stubSources = project.fileTree(kaptTask.stubsDir)
-
-            sourcesFromKotlinTask + stubSources
-        }
-
         kotlinCompile.source(sourcesOutputDir, kotlinSourcesOutputDir)
 
         if (kaptVariantData != null) {

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

@@ -1,8 +1,9 @@
 package org.jetbrains.kotlin.gradle.internal
 
 import org.gradle.api.GradleException
-import org.gradle.api.tasks.TaskAction
+import org.gradle.api.file.FileCollection
-import org.gradle.api.tasks.compile.AbstractCompile
+import org.gradle.api.internal.ConventionTask
+import org.gradle.api.tasks.*
 import org.jetbrains.kotlin.cli.common.arguments.K2JVMCompilerArguments
 import org.jetbrains.kotlin.com.intellij.openapi.util.io.FileUtil
 import org.jetbrains.kotlin.compilerRunner.GradleCompilerEnvironment
@@ -11,20 +12,37 @@ import org.jetbrains.kotlin.compilerRunner.OutputItemsCollectorImpl
 import org.jetbrains.kotlin.gradle.tasks.*
 import java.io.File
 
-open class KaptTask : AbstractCompile() {
+open class KaptTask : ConventionTask() {
     internal val pluginOptions = CompilerPluginOptions()
-    internal lateinit var kotlinCompileTask: KotlinCompile
 
-    fun isInsideDestinationDirs(file: File): Boolean {
+    internal lateinit var kotlinCompileTask: KotlinCompile
+    internal lateinit var stubsDir: File
+
+    private fun isInsideDestinationDirs(file: File): Boolean {
         return FileUtil.isAncestor(destinationDir, file, /* strict = */ false)
                 || FileUtil.isAncestor(classesDir, file, /* strict = */ false)
     }
 
-    lateinit var classesDir: File
+    @OutputDirectory
-    lateinit var stubsDir: File
+    internal lateinit var classesDir: File
+
+    @OutputDirectory
+    lateinit var destinationDir: File
+
+    val classpath: FileCollection
+        @InputFiles get() = kotlinCompileTask.classpath
+
+    val source: FileCollection
+        @InputFiles get() {
+            val sourcesFromKotlinTask = kotlinCompileTask.source
+                    .filter { it.extension == "java" && !isInsideDestinationDirs(it) }
+
+            val stubSources = project.fileTree(stubsDir)
+            return sourcesFromKotlinTask + stubSources
+        }
 
     @TaskAction
-    override fun compile() {
+    fun compile() {
         /** Delete everything inside generated sources and classes output directory
          * (annotation processing is not incremental) */
         destinationDir.clearDirectory()

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

@@ -51,10 +51,6 @@ fun AbstractCompile.mapClasspath(fn: () -> FileCollection) {
     conventionMapping.map("classpath", fn)
 }
 
-internal fun AbstractCompile.mapSource(fn: () -> FileTree) {
-    conventionMapping.map("source", fn)
-}
-
 internal inline fun <reified T : Any> Any.addConvention(name: String, plugin: T) {
     (this as HasConvention).convention.plugins[name] = plugin
 }