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/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<*>) {