DA versus switch: javac allows reference to uninitialized variable

javac allows the following code, generating a class file that does not verify.

class T {
    public static void main(final String[] args) {
        {
            final Object b;
            b = null;
        }
        switch(args.length) {
        case 0:
            int b;
            break;
        case 1:
            int c = b;
        }
    }
}