javac crash for annotation on lambda formal parameter type

[Alex Buckley]

Starting at JDK8 b91, and continuing through b118, this innocuous 
program crashes javac:

--
import java.lang.annotation.*;
import java.util.function.*;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE_USE)
@interface TA {}

class LambdaFormal {
   IntUnaryOperator x = (@TA int y) -> 1;
}
--

with:

java.lang.NullPointerException
         at 
com.sun.tools.javac.code.TypeAnnotations$TypeAnnotationPositions.separateAnnotationsKinds(TypeAnnotations.java:302)
         at 
com.sun.tools.javac.code.TypeAnnotations$TypeAnnotationPositions.visitLambda(TypeAnnotations.java:1080)
         at 
com.sun.tools.javac.tree.JCTree$JCLambda.accept(JCTree.java:1607)
         at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
...

This is weird because I'm sure I've annotated lambda formals in this 
fashion since b90. It's due to TYPE_USE - if TA's target is PARAMETER, 
then the program rightly compiles, while if TA's target is FIELD, you 
get the expected applicability error.

Before I file a P2 bug for this, can anyone add some color to the situation?

Alex

P.S. With a TA target of TYPE_USE, b90 produces a class file without the 
expected RuntimeVisibleTypeAnnotations attribute for @TA. But that's 
less of a concern right now.