contains_requirable_file?

# File lib/rubygems/basic_specification.rb, line 60
  def contains_requirable_file? file
    @contains_requirable_file ||= {}
    @contains_requirable_file[file] ||=
    begin
      if instance_variable_defined?(:@ignored) or
         instance_variable_defined?('@ignored') then
        return false
      elsif missing_extensions? then
        @ignored = true

        warn "Ignoring #{full_name} because its extensions are not built.  " +
             "Try: gem pristine #{name} --version #{version}"
        return false
      end

      suffixes = Gem.suffixes

      full_require_paths.any? do |dir|
        base = "#{dir}/#{file}"
        suffixes.any? { |suf| File.file? "#{base}#{suf}" }
      end
    end ? :yes : :no
    @contains_requirable_file[file] == :yes
  end