# File lib/sass/tree/visitors/check_nesting.rb, line 79
  def invalid_import_parent?(parent, child)
    unless (@parents.map {|p| p.class} & INVALID_IMPORT_PARENTS).empty?
      return "Import directives may not be used within control directives or mixins."
    end
    return if parent.is_a?(Sass::Tree::RootNode)
    return "CSS import directives may only be used at the root of a document." if child.css_import?
  rescue Sass::SyntaxError => e
    e.modify_backtrace(:filename => child.imported_file.options[:filename])
    e.add_backtrace(:filename => child.filename, :line => child.line)
    raise e
  end