This is a bug, but I think it is likely to be coming from a misconfiguration on your end: the preinstalled test checks
  $(ocamlc -where)/ocamlbuild
and if you are in a non-system switch this should not be /usr/local/lib/ocaml.

Did you correctly run

  eval $(opam config en)

after switching?

On Sat, Jun 25, 2016 at 9:57 AM, Soegtrop, Michael <michael.soegtrop@intel.com> wrote:

Dear OCaml Users,

 

Opam works fine for me with the system installed OCaml, but after an opam switch I cannot build ocamlbuild or any package depending on it any more.

 

Building ocamlbuild fails because it explicitly checks if there is already a system installed ocamlbuild:

 

# ERROR: Preinstalled ocamlbuild detected at /usr/local/lib/ocaml/ocamlbuild

# Installation aborted; if you want to bypass this safety check, pass CHECK_IF_PREINSTALLED=false to make

# make: *** [Makefile:333: check-if-preinstalled] Error 2

 

Of cause I can just follow this advice and remove this check, but I wonder how others handle this.

 

Best regards,

 

Michael

 

Intel Deutschland GmbH
Registered Address: Am Campeon 10-12, 85579 Neubiberg, Germany
Tel: +49 89 99 8853-0, www.intel.de
Managing Directors: Christin Eisenschmid, Christian Lamprechter
Chairperson of the Supervisory Board: Nicole Lau
Registered Office: Munich
Commercial Register: Amtsgericht Muenchen HRB 186928