File "pervasives_leitmotiv.ml", line 1:
Warning 63 [erroneous-printed-signature]: The printed interface differs from
  the inferred interface. The inferred interface contained items which could
  not be printed properly due to name collisions between identifiers.
  File "pervasives_leitmotiv.ml", lines 10-12, characters 0-3:
  Definition of module Stdlib
File "_none_", line 1:
  Definition of module Stdlib/2
  Beware that this warning is purely informational and will not catch all
  instances of erroneous printed interface.
type fpclass = A
module Stdlib : sig type fpclass = B end
val f : fpclass -> Stdlib.fpclass -> Stdlib/2.fpclass