Missing symbol for package-private member under joint compilation

Consider the following:

class C {
  @PackageScope static final String X = "x"
}

Reference to "C.X" from a java class in the same package produces error:

Main.java:4: error: cannot find symbol
                            System.err.println(C.X);
                                                ^
      symbol:   variable X
      location: class C
    1 error

This has to do with stubgen running on an early compile phase. In this case, there are no members to generate, only modifiers to adjust so we should be able to sniff this out and handle it special.