class Time

def compare_with_coercion(other)

can be chronologically compared with a Time
Layers additional behavior on Time#<=> so that DateTime and ActiveSupport::TimeWithZone instances 
def compare_with_coercion(other)
  # we're avoiding Time#to_datetime cause it's expensive
  if other.is_a?(Time)
    compare_without_coercion(other.to_time)
  else
    to_datetime <=> other
  end
end