FULL PRODUCT VERSION :
java version "1.9.0-ea"
Java(TM) SE Runtime Environment (build 1.9.0-ea-b82)
Java HotSpot(TM) 64-Bit Server VM (build 1.9.0-ea-b82, mixed mode)


A DESCRIPTION OF THE PROBLEM :
I have an annotation that has a value that is an array of Classes. I use that annotation in another class, but with a class that is not resolvable. Finally, I have an annotation processor that calls Element#getAnnotation on the annotated element. When I compile the test class with my annotation processor running, javac crashes with a ClassCastException (see full output below).

ADDITIONAL REGRESSION INFORMATION:
I've confirmed that this crash occurs in javac 7, 8, and 9.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
From the source code section below, put the code into the named files. Then:

$ javac ReproProcessor.java MyAnnotation.java
$ javac -processor ReproProcessor TestClass.java

You'll get the crash and the stack trace I pasted below.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
javac reports a "cannot find symbol" error but does not crash.
ACTUAL -
javac crashes.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
TestClass.java:2: error: cannot find symbol
  @MyAnnotation(classes = {ClassThatDoesNotExist.class})
                           ^
  symbol: class ClassThatDoesNotExist
  location: class TestClass
warning: Supported source version 'RELEASE_7' from annotation processor 'ReproProcessor' less than -source '1.9'
1 error
1 warning


An annotation processor threw an uncaught exception.
Consult the following stack trace for details.
java.lang.ClassCastException: com.sun.tools.javac.code.Attribute$UnresolvedClass cannot be cast to com.sun.tools.javac.code.Attribute$Class
at com.sun.tools.javac.model.AnnotationProxyMaker$ValueVisitor.visitArray(AnnotationProxyMaker.java:192)
at com.sun.tools.javac.code.Attribute$Array.accept(Attribute.java:327)
at com.sun.tools.javac.model.AnnotationProxyMaker$ValueVisitor.getValue(AnnotationProxyMaker.java:167)
at com.sun.tools.javac.model.AnnotationProxyMaker.generateValue(AnnotationProxyMaker.java:145)
at com.sun.tools.javac.model.AnnotationProxyMaker.getAllReflectedValues(AnnotationProxyMaker.java:104)
at com.sun.tools.javac.model.AnnotationProxyMaker.generateAnnotation(AnnotationProxyMaker.java:90)
at com.sun.tools.javac.model.AnnotationProxyMaker.generateAnnotation(AnnotationProxyMaker.java:81)
at com.sun.tools.javac.code.AnnoConstruct.getAnnotation(AnnoConstruct.java:184)
at ReproProcessor.process(ReproProcessor.java:13)
at com.sun.tools.javac.processing.JavacProcessingEnvironment.callProcessor(JavacProcessingEnvironment.java:827)
at com.sun.tools.javac.processing.JavacProcessingEnvironment.discoverAndRunProcs(JavacProcessingEnvironment.java:739)
at com.sun.tools.javac.processing.JavacProcessingEnvironment.access$2000(JavacProcessingEnvironment.java:97)
at com.sun.tools.javac.processing.JavacProcessingEnvironment$Round.run(JavacProcessingEnvironment.java:1047)
at com.sun.tools.javac.processing.JavacProcessingEnvironment.doProcessing(JavacProcessingEnvironment.java:1154)
at com.sun.tools.javac.main.JavaCompiler.processAnnotations(JavaCompiler.java:1150)
at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:838)
at com.sun.tools.javac.main.Main.compile(Main.java:254)
at com.sun.tools.javac.main.Main.compile(Main.java:142)
at com.sun.tools.javac.Main.compile(Main.java:56)
at com.sun.tools.javac.Main.main(Main.java:42)


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
MyAnnotation.java:
public @interface MyAnnotation {
  Class<?>[] classes() default {};
}

ReproProcessor.java:
import javax.annotation.processing.*;
import javax.lang.model.SourceVersion;
import javax.lang.model.element.*;
import java.util.Set;

@SupportedAnnotationTypes("MyAnnotation")
@SupportedSourceVersion(SourceVersion.RELEASE_7)
public class ReproProcessor extends AbstractProcessor {
  @Override
  public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
    Set<? extends Element> elems = roundEnv.getElementsAnnotatedWith(MyAnnotation.class);
    for (Element elem : elems) {
      System.out.println(elem.getAnnotation(MyAnnotation.class));
    }

    return false;
  }
}

TestClass.java:
public class TestClass {
  @MyAnnotation(classes = {ClassThatDoesNotExist.class})
  public void foo() {}
}
---------- END SOURCE ----------