warning: toplevel constant File referenced by IO::File

I want to delete a file from Application::Mail.download. The problem is that inside Application module, File.delete calls Application::File.delete.

module Application
  class File
    def delete
    end
  end
  class Mail
    def self.download
      File.delete "mail.eml"
    end
  end
end

Application::Mail.download

Run this code and you will get error message:

Exception: undefined method `delete' for Application::File:Class

I could rename Application::File to something else, but I created Application module because I wanted to name my classes as I wish without conflicts with Ruby classes.

One solution is to specify that I want to call IO::File.delete.

def self.download
  IO::File.delete "mail.eml"
end

But then I get this warning:

warning: toplevel constant File referenced by IO::File

How to ignore warning thread at ruby-forum.com provided the solution to removing warning. Add this at the beginning of the file:

$VERBOSE = nil

But, I want to see other warnings. I know I can change the value of $VERBOSE to nil just before I call IO::File.delete and then change it back. That just feels wrong. Why am I getting that warning after all? Why do I get the warning after calling IO::File.delete? Am I doing something wrong?