Kapt3: Handle exceptions while annotation processing gracefully

plugins/kapt3/src/org/jetbrains/kotlin/kapt3/KaptRunner.kt

@@ -20,7 +20,9 @@ import com.sun.tools.javac.comp.CompileStates
 import com.sun.tools.javac.file.JavacFileManager
 import com.sun.tools.javac.main.JavaCompiler
 import com.sun.tools.javac.main.Option
+import com.sun.tools.javac.processing.AnnotationProcessingError
 import com.sun.tools.javac.processing.JavacProcessingEnvironment
+import com.sun.tools.javac.tree.JCTree
 import com.sun.tools.javac.util.Context
 import com.sun.tools.javac.util.Log
 import com.sun.tools.javac.util.Options
@@ -28,21 +30,65 @@ import java.io.File
 import java.io.PrintWriter
 import javax.annotation.processing.Processor
 import javax.tools.JavaFileManager
+import com.sun.tools.javac.util.List as JavacList
 
 class KaptError : RuntimeException {
-    constructor(message: String) : super(message)
-    constructor(message: String, cause: Throwable) : super(message, cause)
+    val kind: Kind
+
+    enum class Kind(val message: String) {
+        JAVA_FILE_PARSING_ERROR("Java file parsing error"),
+        EXCEPTION("Exception while annotation processing"),
+        UNKNOWN("Unknown error while annotation processing")
+    }
+
+    constructor(kind: Kind) : super(kind.message) {
+        this.kind = kind
+    }
+
+    constructor(kind: Kind, cause: Throwable) : super(kind.message, cause) {
+        this.kind = kind
+    }
 }
 
 class KaptRunner {
-    fun doAnnotationProcessing(javaSourceFiles: List<File>, processors: List<Processor>, sourceOutputDir: File, classOutputDir: File) {
-        val context = Context()
+    private val context = Context()
+    private val options: Options
+
+    init {
         JavacFileManager.preRegister(context)
         KaptJavaCompiler.preRegister(context)
 
-        val options = Options.instance(context)
+        options = Options.instance(context)
         context.put(Log.outKey, PrintWriter(System.err, true))
+    }
+
+    fun parseJavaFiles(
+            javaSourceFiles: List<File>,
+            classpath: List<File>
+    ): JavacList<JCTree.JCCompilationUnit> {
+        classpath.forEach { options.put(Option.CLASSPATH, it.canonicalPath) }
+
+        val fileManager = context.get(JavaFileManager::class.java) as JavacFileManager
+        val compiler = JavaCompiler.instance(context) as KaptJavaCompiler
+
+        try {
+            val javaFileObjects = fileManager.getJavaFileObjectsFromFiles(javaSourceFiles)
+            return compiler.parseFiles(javaFileObjects)
+        } finally {
+            fileManager.close()
+            compiler.close()
+        }
+    }
+
+    fun doAnnotationProcessing(
+            javaSourceFiles: List<File>,
+            processors: List<Processor>,
+            classpath: List<File>,
+            sourceOutputDir: File,
+            classOutputDir: File
+    ) {
         options.put(Option.PROC, "only") // Only process annotations
+        classpath.forEach { options.put(Option.CLASSPATH, it.canonicalPath) }
         options.put(Option.S, sourceOutputDir.canonicalPath)
         options.put(Option.D, classOutputDir.canonicalPath)
 
@@ -56,13 +102,20 @@ class KaptRunner {
             val javaFileObjects = fileManager.getJavaFileObjectsFromFiles(javaSourceFiles)
             val parsedJavaFiles = compiler.parseFiles(javaFileObjects)
             if (compiler.shouldStop(CompileStates.CompileState.PARSE)) {
-                throw KaptError("Error while parsing Java files.")
+                throw KaptError(KaptError.Kind.JAVA_FILE_PARSING_ERROR)
             }
 
-            val compilerAfterAnnotationProcessing = compiler.processAnnotations(compiler.enterTrees(parsedJavaFiles))
-            compilerAfterAnnotationProcessing.close()
+            val compilerAfterAnnotationProcessing: JavaCompiler? = null
+            try {
+                compiler.processAnnotations(compiler.enterTrees(parsedJavaFiles))
+            } catch (e: AnnotationProcessingError) {
+                throw KaptError(KaptError.Kind.EXCEPTION, e.cause ?: e)
+            }
+
+            compilerAfterAnnotationProcessing?.close()
         } finally {
             processingEnvironment.close()
+            compiler.close()
             fileManager.close()
         }
     }

plugins/kapt3/test/KaptRunnerTest.kt

@@ -1,3 +1,4 @@
+import org.jetbrains.kotlin.kapt3.KaptError
 import org.jetbrains.kotlin.kapt3.KaptRunner
 import org.junit.Assert
 import org.junit.Assert.*
@@ -27,11 +28,8 @@ import javax.lang.model.element.TypeElement
 class KaptRunnerTest {
     private companion object {
         val TEST_DATA_DIR = File("plugins/kapt3/testData/runner")
-    }
 
-    @Test
-    fun testSimple() {
-        val processor = object : AbstractProcessor() {
+        val SIMPLE_PROCESSOR = object : AbstractProcessor() {
             override fun process(annotations: Set<TypeElement>, roundEnv: RoundEnvironment): Boolean {
                 for (annotation in annotations) {
                     val annotationName = annotation.simpleName.toString()
@@ -54,12 +52,16 @@ class KaptRunnerTest {
 
             override fun getSupportedAnnotationTypes() = setOf("test.MyAnnotation")
         }
+    }
 
+    @Test
+    fun testSimple() {
         val sourceOutputDir = Files.createTempDirectory("kaptRunner").toFile()
         try {
             KaptRunner().doAnnotationProcessing(
                     listOf(File(TEST_DATA_DIR, "Simple.java")),
-                    listOf(processor),
+                    listOf(SIMPLE_PROCESSOR),
+                    emptyList(), // classpath
                     sourceOutputDir,
                     sourceOutputDir)
             val myMethodFile = File(sourceOutputDir, "generated/MyMethodMyAnnotation.java")
@@ -68,4 +70,43 @@ class KaptRunnerTest {
             sourceOutputDir.deleteRecursively()
         }
     }
+
+    @Test
+    fun testException() {
+        val exceptionMessage = "Here we are!"
+
+        val processor = object : AbstractProcessor() {
+            override fun process(annotations: Set<TypeElement>, roundEnv: RoundEnvironment): Boolean {
+                throw RuntimeException(exceptionMessage)
+            }
+
+            override fun getSupportedAnnotationTypes() = setOf("test.MyAnnotation")
+        }
+
+        try {
+            KaptRunner().doAnnotationProcessing(
+                    listOf(File(TEST_DATA_DIR, "Simple.java")),
+                    listOf(processor),
+                    emptyList(),
+                    TEST_DATA_DIR,
+                    TEST_DATA_DIR)
+        } catch (e: KaptError) {
+            assertEquals(KaptError.Kind.EXCEPTION, e.kind)
+            assertEquals("Here we are!", e.cause!!.message)
+        }
+    }
+
+    @Test
+    fun testParsingError() {
+        try {
+            KaptRunner().doAnnotationProcessing(
+                    listOf(File(TEST_DATA_DIR, "ParseError.java")),
+                    listOf(SIMPLE_PROCESSOR),
+                    emptyList(),
+                    TEST_DATA_DIR,
+                    TEST_DATA_DIR)
+        } catch (e: KaptError) {
+            assertEquals(KaptError.Kind.JAVA_FILE_PARSING_ERROR, e.kind)
+        }
+    }
 }

plugins/kapt3/testData/runner/ParseError.java

@@ -0,0 +1 @@
+BLAHBLAH