Kapt3: Support 'processors' option in Gradle plugin (KT-8558)

Also warn if kapt3 options are used without the "apply plugin: 'kotlin-kapt'" specified.

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

@@ -43,6 +43,21 @@ class Kapt3IT : BaseGradleIT() {
         KAPT_SUCCESSFUL_REGEX.findAll(this.output).count() > 0
     }
 
+    @Test
+    fun testAnnotationProcessorAsFqName() {
+        val project = Project("annotationProcessorAsFqName", GRADLE_VERSION, directoryPrefix = "kapt2")
+
+        project.build("build") {
+            assertSuccessful()
+            assertKaptSuccessful()
+            assertContains(":compileKotlin")
+            assertContains(":compileJava")
+            assertFileExists("build/generated/source/kapt/main/example/TestClassGenerated.java")
+            assertFileExists("build/classes/main/example/TestClass.class")
+            assertFileExists("build/classes/main/example/TestClassGenerated.class")
+        }
+    }
+
     @Test
     fun testSimple() {
         val project = Project("simple", GRADLE_VERSION, directoryPrefix = "kapt2")

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

@@ -0,0 +1,28 @@
+buildscript {
+    repositories {
+        mavenLocal()
+        mavenCentral()
+    }
+    dependencies {
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+    }
+}
+
+apply plugin: "java"
+apply plugin: "kotlin"
+apply plugin: "kotlin-kapt"
+
+repositories {
+    mavenLocal()
+    mavenCentral()
+}
+
+kapt {
+    processors = "example.ExampleAnnotationProcessor"
+}
+
+dependencies {
+    compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+    kapt "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+    compile "org.jetbrains.kotlin:annotation-processor-example:$kotlin_version"
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kapt2/annotationProcessorAsFqName/gradle.properties

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

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kapt2/annotationProcessorAsFqName/src/main/java/test.kt

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2010-2017 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 example
+
+@example.ExampleAnnotation
+class TestClass

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

@@ -51,6 +51,14 @@ internal fun Project.initKapt(
     val kaptExtension = extensions.getByType(KaptExtension::class.java)
     val kotlinAfterJavaTask: KotlinCompile?
 
+    fun warnUnsupportedKapt1Option(optionName: String) {
+        kotlinTask.logger.kotlinWarn("'$optionName' option is not supported by this kapt implementation. " +
+                "Please add the \"apply plugin: 'kotlin-kapt\" line to your build script to enable it.")
+    }
+
+    if (kaptExtension.processors.isNotEmpty()) warnUnsupportedKapt1Option("processors")
+    if (kaptExtension.correctErrorTypes) warnUnsupportedKapt1Option("correctErrorTypes")
+
     if (kaptExtension.generateStubs) {
         kotlinAfterJavaTask = createKotlinAfterJavaTask(javaTask, kotlinTask, kotlinOptions, tasksProvider)
 

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

@@ -173,6 +173,11 @@ class Kapt3KotlinGradleSubplugin : KotlinGradleSubplugin<KotlinCompile> {
         pluginOptions += SubpluginOption("sources", generatedFilesDir.canonicalPath)
         pluginOptions += SubpluginOption("classes", getKaptClasssesDir(project, sourceSetName).canonicalPath)
 
+        val annotationProcessors = kaptExtension.processors
+        if (annotationProcessors.isNotEmpty()) {
+            pluginOptions += SubpluginOption("processors", annotationProcessors)
+        }
+
         val androidPlugin = variantData?.let {
             project.extensions.findByName("android") as? BaseExtension
         }

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

@@ -30,6 +30,8 @@ open class KaptExtension {
 
     open var correctErrorTypes: Boolean = false
 
+    open var processors: String = ""
+
     private var closure: Closure<*>? = null
 
     open fun arguments(closure: Closure<*>) {