Opam / findlib warning "... has multiple definitions"

Question

I have a local installation of opam in my home directory and a (fedora) package installation of the ocaml compiler and several libraries.

Running a ocamlbuild command in any project gives a lot of warnings:

findlib: [WARNING] Package dynlink has multiple definitions in /home/choeger/.opam/system/lib/dynlink/META, /usr/lib64/ocaml/dynlink/META
findlib: [WARNING] Package bigarray has multiple definitions in /home/choeger/.opam/system/lib/bigarray/META, /usr/lib64/ocaml/bigarray/META
findlib: [WARNING] Package unix has multiple definitions in /home/choeger/.opam/system/lib/unix/META, /usr/lib64/ocaml/unix/META
findlib: [WARNING] Package camlp4 has multiple definitions in /home/choeger/.opam/system/lib/camlp4/META, /usr/lib64/ocaml/camlp4/META
findlib: [WARNING] Package threads has multiple definitions in /home/choeger/.opam/system/lib/threads/META, /usr/lib64/ocaml/threads/META

My understanding of opam is that multiple installations in different locations are supported, but these warnings clutter any compilation output.

Is there a way to tell findlib that I know of these other installations and to not print these useless warnings?

edit: Since I was asked for my ocamlfind output:

choeger@daishi ~ % ocamlfind printconf
    Effective configuration:
    Configuration file:
        /home/choeger/.opam/system/lib/findlib.conf
    Search path:
        /home/choeger/.opam/system/lib
        /usr/lib64/ocaml
    Packages will be installed in/removed from:
        /home/choeger/.opam/system/lib
    META files will be installed in/removed from:
        the corresponding package directories
    The standard library is assumed to reside in:
        /usr/lib64/ocaml
    The ld.conf file can be found here:
        /usr/lib64/ocaml/ld.conf

Could this be caused by not executing, `eval \`opam config env\``? The Fedora package is the `System` compiler defined in OPAM? — nlucaroni, Apr 07 '14 at 13:36
Does this happen with any compiler that you switch to through OPAM? — nlucaroni, Apr 07 '14 at 15:09
My guess is that `OCAMLPATH` is being set and it's being appending to that Search Path list. I don't believe that is necessary --I don't have it set. — nlucaroni, Apr 07 '14 at 17:31
Yes, OCAMLPATH is set, but without it, findlib does not find any OPAM packages. — choeger, Apr 14 '14 at 06:30
Check the contents of that META file, you'll see that is the `Unix` module distributed with OCaml. I think everything in `.opam` is fine, it's the system installed libraries that "shouldn't" be visible. — nlucaroni, Apr 15 '14 at 13:31
Yes, I can see this line. `version = "[distributed with Ocaml]"`, but I want to use my system's ocaml distribution. So where do these libs actually come from? — choeger, Apr 16 '14 at 10:11
exactly in the other location mentioned in the search path, /usr/lib64/ocaml — nlucaroni, Apr 20 '14 at 20:28

score 1 · Answer 1 · answered Apr 22 '14 at 13:27

I just found the solution to the problem:

 sudo yum remove ocaml-findlib

Apparently, this package ships with all those double-defined ocaml libraries. I still think opam should be able to deal with this situation (IMO the more specific package manager should always be sensible to more unspecific installations), but opam is not packaged by fedora yet, so something like this should be expected. At least the annoying warning is gone.

Opam / findlib warning "... has multiple definitions"

1 Answers1