# File lib/brakeman/checks/check_sql.rb, line 553
  def check_string_arg exp
    if safe_value? exp
      nil
    elsif string_building? exp
      check_for_string_building exp
    elsif string_interp? exp
      check_string_interp exp
    elsif call? exp and exp.method == :to_s
      check_string_arg exp.target
    else
      exp
    end
  end