Compplugin is a module from the compiler distribution that indeed is new in
4.04.0. It is not included in ocamlcommon.cma. It is part of
ocamlbytecomp.cma, but not of ocamloptcomp.cma, and I believe that the
latter omission is a bug (as Optcompile depends on it), so maybe it should
really be in ocamlcommon.cma.

This looks like an upstream bug (in the OCaml distribution). Could you open
a Mantis issue?

As a workaround, you may be able to link to the compplugin module
separately, it is installed in the $(ocamlfind query compiler-libs)
directory.

On Mon, Nov 7, 2016 at 3:10 PM, Christoph Höger <
christoph.hoeger@tu-berlin.de> wrote:

> Dear all,
>
> today I attempted to migrate my stack towards 4.04.0 - unfortunately
> ppx_monadic is not yet available for that language version. I attempted
> to build it myself, but to no avail:
>
> Error: Required module `Compplugin' is unavailable
>
> This error is newly introduced into 4.04.0 (and does not exist in the
> HEAD version). Compplugin should be provided by compilerlibs.common, so
> I assume I need to fix the build system somehow.
>
> Does anyone have any idea how to fix this?
>
> regards,
>
> Christoph
> --
> Christoph Höger
>
> Technische Universität Berlin
> Fakultät IV - Elektrotechnik und Informatik
> Übersetzerbau und Programmiersprachen
>
> Sekr. TEL12-2, Ernst-Reuter-Platz 7, 10587 Berlin
>
> Tel.: +49 (30) 314-24890
> E-Mail: christoph.hoeger@tu-berlin.de
>
>