oasis picks up wrong ocamlbuild

Question

I try to compile an Ocaml project with an Ocaml version provided by Opam. My ocamlbuild, ocamlfind, and oasis seem OK :

/Users/fred/.opam/4.02.1/bin/ocamlbuild
dhcp-182-73:compil fred$ which ocamlfind
/Users/fred/.opam/4.02.1/bin/ocamlfind
dhcp-182-73:compil fred$ which oasis
/Users/fred/.opam/4.02.1/bin/oasis

But when I try to compile, it seems that a wrong version of ocamlbuild is called, and even the version of ocamlfind is right, I think that it explains why ocamlfind can't find the sexplib library.

$ make
ocaml setup.ml -build 
Finished, 0 targets (0 cached) in 00:00:00.
+ /Users/fred/.opam/system/bin/ocamlfind ocamldep -package threads -package sexplib.syntax -package core -package comparelib.syntax -modules  src/tricot/tricot.mli > src/tricot/tricot.mli.depends
ocamlfind: Package `sexplib.syntax' not found
Command exited with code 2.
Compilation unsuccessful after building 1 target (0 cached) in 00:00:00.
E: Failure("Command ''/usr/local/bin/ocamlbuild' src/tricot/tricot.cma src/tricot/tricot.cmxa src/tricot/tricot.a src/tricot/tricot.cmxs src/compil/compil.cma src/compil/compil.cmxa src/compil/compil.a src/compil/compil.cmxs src/main.native -use-ocamlfind -tag debug' terminated with error code 10")
make: *** [build] Error 1

I've tried to tell oasis which version of ocambuild to use without success, does someone knows how it could be done ? Thanks

Answer 1

Try deleting setup.data and running make again. Oasis caches the paths the first time you try to build, and doesn't update them automatically afterwards. Perhaps you tried to build it, then used opam switch, then tried to build it again?

Answer 2

You must be missing a

eval $(opam config env)

See the documentation of opam switch.

Note that normally opam's install procedure should have made so that this gets invoked automatically on new shells. You may want to run opam init again it will prompt you to agree to make changes to your .profile so that everything is in order when you start new shells.

EDIT: In fact it looks like you changed to the system switch between the two invocations you show us. So it seems that in the system switch sexp is not installed. In anycase whenever you opam switch in a shell always invoke the command I mentioned above so that the right paths are setup.