Thanks for the clarifications. I forward to Luc and here is the answer I got.
> As far as I understand the issue, info files are installed by > "GNU install-info" aka ginstall-info. > > From hand experiments on an UBUNTU 14.04, "dropping relevant files > into files under /usr/share/info" is not enough. One should > also add an entry for ocaml into /usr/share/info/dir. > > This can be done from the command line as > # sudo ginstall-info /usr/share/info/ocaml.info.gz /usr/share/info/dir > > There is no need to invoke ginstall-info on other info files, as > "apt-get install ocaml-doc" apparently does. However, the only > consequence seems to be warnings. > > > > Can you please tell us how to test info files? So far, I've been unable to > > get them > > working through the "info" command-line utility. All what we do in the > > package is to > > drop relevant files under /usr/share/info. So, nothing seems specific to > > Debian wrt > > this issue. > > > > Also, there are a bunch of generated files, not only ocaml.info.body.gz. > > The complete > > list is: > > - `ocaml.info.hocaml.info.kwd.hind.gz' > > - `ocaml.info.hocaml.info.hind.gz' > > - `ocaml.info.body.gz' > > - `ocaml.info.haux.gz' > > > > Regards, > > So the conclusion is (?) avoid spurious warnings during the installation > of the package ocaml-doc by applying ginstall-info to the file ocaml.info.gz > and to this file only. > > As far as I understand, it seems a debian related issue, at least > a packaging one, as described above.This is probably due to my very > naive point of view, but I don't see so many difficulties.