empty export warning

[Serge D. Mechveliani]

People, 

here is a more precise report about empty _export_ in 
ghc-6.8.1-candidate:

I use
  --------------------------------
  module M1 (f, module M2)
  where
  import M2 ()
  f = ...
  --------------------------------

in the situation when  M1  imports some instances from  M2  and 
reexports these instances.

And  ghc-6.8.1-candidate  reports 

  "Warning: The export item `module M2' exports nothing"

1) Can I fix anything here?
2) Should this warning be different?

Regards,

-----------------
Serge Mechveliani
mechvel at botik.ru