bogus RuntimeVisibleTypeAnnotations for unused local in a block

A colleague reports:

When an unused local that has a TYPE_USE annotation applied to it is nested inside a synchronized block, javac emits an entry in the RuntimeVisibleTypeAnnotations (or RuntimeInvisibleTypeAnnotations) whose start_pc and length are bogus. This causes issues with ASM and other bytecode reading tools.

Repro:

Foo.java
===========================================
import java.lang.annotation.Target;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;

class Foo {

  Object lock;

  void something() {
    synchronized(lock) {
      @MyAnno Object o = new Object();
    }
  }
}

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

javac Foo.java
javap -v -c Foo

============================================
Classfile /usr/local/google/home/glorioso/Desktop/Foo.class
  Last modified Sep 21, 2017; size 469 bytes
  MD5 checksum d422c35506a08f107516ad8c5e82dea5
  Compiled from "Foo.java"
class Foo
  minor version: 0
  major version: 52
  flags: ACC_SUPER
Constant pool:
   #1 = Methodref #3.#20 // java/lang/Object."<init>":()V
   #2 = Fieldref #4.#21 // Foo.lock:Ljava/lang/Object;
   #3 = Class #22 // java/lang/Object
   #4 = Class #23 // Foo
   #5 = Utf8 lock
   #6 = Utf8 Ljava/lang/Object;
   #7 = Utf8 <init>
   #8 = Utf8 ()V
   #9 = Utf8 Code
  #10 = Utf8 LineNumberTable
  #11 = Utf8 something
  #12 = Utf8 StackMapTable
  #13 = Class #23 // Foo
  #14 = Class #22 // java/lang/Object
  #15 = Class #24 // java/lang/Throwable
  #16 = Utf8 RuntimeVisibleTypeAnnotations
  #17 = Utf8 LMyAnno;
  #18 = Utf8 SourceFile
  #19 = Utf8 Foo.java
  #20 = NameAndType #7:#8 // "<init>":()V
  #21 = NameAndType #5:#6 // lock:Ljava/lang/Object;
  #22 = Utf8 java/lang/Object
  #23 = Utf8 Foo
  #24 = Utf8 java/lang/Throwable
{
  java.lang.Object lock;
    descriptor: Ljava/lang/Object;
    flags:

  Foo();
    descriptor: ()V
    flags:
    Code:
      stack=1, locals=1, args_size=1
         0: aload_0
         1: invokespecial #1 // Method java/lang/Object."<init>":()V
         4: return
      LineNumberTable:
        line 6: 0

  void something();
    descriptor: ()V
    flags:
    Code:
      stack=2, locals=4, args_size=1
         0: aload_0
         1: getfield #2 // Field lock:Ljava/lang/Object;
         4: dup
         5: astore_1
         6: monitorenter
         7: new #3 // class java/lang/Object
        10: dup
        11: invokespecial #1 // Method java/lang/Object."<init>":()V
        14: astore_2
        15: aload_1
        16: monitorexit
        17: goto 25
        20: astore_3
        21: aload_1
        22: monitorexit
        23: aload_3
        24: athrow
        25: return
      Exception table:
         from to target type
             7 17 20 any
            20 23 20 any
      LineNumberTable:
        line 11: 0
        line 12: 7
        line 13: 15
        line 14: 25
      StackMapTable: number_of_entries = 2
        frame_type = 255 /* full_frame */
          offset_delta = 20
          locals = [ class Foo, class java/lang/Object ]
          stack = [ class java/lang/Throwable ]
        frame_type = 250 /* chop */
          offset_delta = 4
      RuntimeVisibleTypeAnnotations:
        0: #17(): LOCAL_VARIABLE, {start_pc=65535, length=65535, index=2}
}
SourceFile: "Foo.java"