How does jbuilder (or other tools) decide order of args for compile commandline?

Ecosystem
1

I have a case in which I build a native executable using jbuilder, and the ocamlopt.opt command line has two .cmxa files in the wrong order. I don’t understand everything going on in the command line; what I mean is that I get an error from the command line that jbuilder constructs, but when I reverse the cmxa files and run the ocamlopt.opt with the cmxa files reversed, it compiles the executable.

Or maybe this is not a jbuilder issue, but has to do with some other tool?

jbuild file:

(jbuild_version 1)

(executables
 ((names (test))
	 (public_names (test))
  (package yo)
  (libraries (bigarray hdf5_caml))
  (modes (native))
 ))

Command line that jbuilder (and friends) constructs, along with the error:

(cd _build/default && /Users/marshall/.opam/4.05.0+flambda/bin/ocamlopt.opt -w -40 -g -o src/yo/test.exe -I /Users/marshall/.opam/4.05.0+flambda/lib/hdf5_caml -I /Users/marshall/.opam/4.05.0+flambda/lib/hdf5_raw -I /Users/marshall/.opam/4.05.0+flambda/lib/ocaml /Users/marshall/.opam/4.05.0+flambda/lib/ocaml/unix.cmxa /Users/marshall/.opam/4.05.0+flambda/lib/hdf5_raw/hdf5_raw.cmxa /Users/marshall/.opam/4.05.0+flambda/lib/ocaml/bigarray.cmxa /Users/marshall/.opam/4.05.0+flambda/lib/hdf5_caml/hdf5_caml.cmxa src/yo/test.cmx)
File "_none_", line 1:
Error: No implementations provided for the following modules:
         Bigarray referenced from /Users/marshall/.opam/4.05.0+flambda/lib/hdf5_raw/hdf5_raw.cmxa(Hdf5_raw)

Here’s the ocamlopt.opt command line formatted for easy reading:

~/.opam/4.05.0+flambda/bin/ocamlopt.opt -w -40 -g -o src/yo/test.exe 
  -I ~/.opam/4.05.0+flambda/lib/hdf5_caml
  -I ~/.opam/4.05.0+flambda/lib/hdf5_raw
  -I ~/.opam/4.05.0+flambda/lib/ocaml
  ~/.opam/4.05.0+flambda/lib/ocaml/unix.cmxa
  ~/.opam/4.05.0+flambda/lib/hdf5_raw/hdf5_raw.cmxa
  ~/.opam/4.05.0+flambda/lib/ocaml/bigarray.cmxa
  ~/.opam/4.05.0+flambda/lib/hdf5_caml/hdf5_caml.cmxa
  src/yo/test.cmx

If I reverse these two arguments

  ~/.opam/4.05.0+flambda/lib/hdf5_raw/hdf5_raw.cmxa
  ~/.opam/4.05.0+flambda/lib/ocaml/bigarray.cmxa

the command succeeds. I gather that the Bigarray lib needs to be first so that Hdf5_raw can reference it. (Hdf5_raw does in fact use Bigarray.)

Any idea about what’s going wrong when the command line is constructed?

2

Or maybe this is not a jbuilder issue, but has to do with some other tool?

This looks more like a packaging error on the hdf5 side that forget to declare its dependency on the Biggarray library.

1 Like
3

Ah, thanks @octachron. That was it. I added “bigarray” to the “Library hdf5_caml” section of _oasis, and it solved the problem.