Kapt: Remove generated output directory each time before annotation processing

(cherry picked from commit c4b772a)

libraries/tools/kotlin-gradle-plugin/src/test/kotlin/org/jetbrains/kotlin/gradle/Kapt2IT.kt

@@ -24,6 +24,7 @@ import java.io.FileFilter
 class Kapt2IT: BaseGradleIT() {
     companion object {
         private const val GRADLE_VERSION = "2.10"
+        private const val GRADLE_2_14_VERSION = "2.14.1"
         private const val ANDROID_GRADLE_PLUGIN_VERSION = "1.5.+"
     }
 
@@ -165,4 +166,47 @@ class Kapt2IT: BaseGradleIT() {
             assertFileExists("build/generated/source/kapt2/release/io/realm/DefaultRealmModuleMediator.java")
         }
     }
+
+    @Test
+    fun testGeneratedDirectoryIsUpToDate() {
+        val project = Project("generatedDirUpToDate", GRADLE_2_14_VERSION, directoryPrefix = "kapt2")
+
+        project.build("build") {
+            assertSuccessful()
+            assertKaptSuccessful()
+            assertContains(":compileKotlin")
+            assertContains(":compileJava")
+            assertFileExists("build/classes/main/example/TestClass.class")
+
+            assertFileExists("build/generated/source/kapt2/main/example/TestClassGenerated.java")
+            assertFileExists("build/generated/source/kapt2/main/example/SourceAnnotatedTestClassGenerated.java")
+            assertFileExists("build/generated/source/kapt2/main/example/BinaryAnnotatedTestClassGenerated.java")
+            assertFileExists("build/generated/source/kapt2/main/example/RuntimeAnnotatedTestClassGenerated.java")
+
+            assertFileExists("build/classes/main/example/TestClassGenerated.class")
+            assertFileExists("build/classes/main/example/SourceAnnotatedTestClassGenerated.class")
+            assertFileExists("build/classes/main/example/BinaryAnnotatedTestClassGenerated.class")
+            assertFileExists("build/classes/main/example/RuntimeAnnotatedTestClassGenerated.class")
+        }
+
+        val testKt = project.projectDir.getFileByName("test.kt")
+        testKt.writeText(testKt.readText().replace("@ExampleBinaryAnnotation", ""))
+
+        project.build("build") {
+            assertSuccessful()
+            assertContains(":compileKotlin")
+            assertContains(":compileJava")
+            assertFileExists("build/classes/main/example/TestClass.class")
+
+            assertFileExists("build/generated/source/kapt2/main/example/TestClassGenerated.java")
+            assertFileExists("build/generated/source/kapt2/main/example/SourceAnnotatedTestClassGenerated.java")
+            /*!*/   assertNoSuchFile("build/generated/source/kapt2/main/example/BinaryAnnotatedTestClassGenerated.java")
+            assertFileExists("build/generated/source/kapt2/main/example/RuntimeAnnotatedTestClassGenerated.java")
+
+            assertFileExists("build/classes/main/example/TestClassGenerated.class")
+            assertFileExists("build/classes/main/example/SourceAnnotatedTestClassGenerated.class")
+            /*!*/   assertNoSuchFile("build/classes/main/example/BinaryAnnotatedTestClassGenerated.class")
+            assertFileExists("build/classes/main/example/RuntimeAnnotatedTestClassGenerated.class")
+        }
+    }
 }

libraries/tools/kotlin-gradle-plugin/src/test/resources/testProject/kapt2/generatedDirUpToDate/build.gradle

@@ -0,0 +1,32 @@
+buildscript {
+    repositories {
+        mavenCentral()
+        maven {
+            url 'file://' + pathToKotlinPlugin
+        }
+    }
+    dependencies {
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:0.1-SNAPSHOT"
+    }
+}
+
+apply plugin: "java"
+apply plugin: "kotlin"
+apply plugin: "kotlin-kapt"
+
+repositories {
+    maven {
+        url 'file://' + pathToKotlinPlugin
+    }
+    mavenCentral()
+}
+
+dependencies {
+    compile "org.jetbrains.kotlin:kotlin-stdlib:0.1-SNAPSHOT"
+    compile "org.jetbrains.kotlin:annotation-processor-example:0.1-SNAPSHOT"
+    kapt "org.jetbrains.kotlin:annotation-processor-example:0.1-SNAPSHOT"
+}
+
+task show << {
+    buildscript.configurations.classpath.each { println it }
+}

libraries/tools/kotlin-gradle-plugin/src/test/resources/testProject/kapt2/generatedDirUpToDate/gradle.properties

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

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

@@ -0,0 +1,23 @@
+/*
+ * Copyright 2010-2016 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
+
+@ExampleAnnotation
+@ExampleSourceAnnotation
+@ExampleBinaryAnnotation
+@ExampleRuntimeAnnotation
+class TestClass

plugins/annotation-processing/src/org/jetbrains/kotlin/annotation/processing/AnnotationProcessingExtension.kt

@@ -87,6 +87,10 @@ abstract class AbstractAnnotationProcessingExtension(
             return null
         }
 
+        // Clean the generated source directory even if we don't run any annotation processors
+        generatedSourcesOutputDir.deleteRecursively()
+        generatedSourcesOutputDir.mkdirs()
+
         val processors = loadAnnotationProcessors()
         if (processors.isEmpty()) {
             log { "No annotation processors detected, exiting" }