Test dune configurator with cross-compilers.

discover.ml

module C = Configurator.V1

let () =
  C.main ~name:"test-dune-configurator" (fun c ->
      let has_alsa =
        C.c_test c
          {|
        #include <alsa/asoundlib.h>
        int main() {
          snd_pcm_t *pcm_handle;
          return 0;
        }
      |}
      in

      C.C_define.gen_header_file c ~fname:"config.h"
        [
          ("HAS_ALSA", Switch has_alsa);
        ])

dune

(library
 (name test_dune_configurator)
 (modules test_dune_configurator)
 (foreign_stubs
  (extra_deps config.h)
  (language c)
  (names test_dune_configurator)))

(executable
 (name print_conf)
 (modules print_conf)
 (libraries test_dune_configurator))

(executable
 (name discover)
 (modules discover)
 (libraries dune.configurator))

(rule
 (targets config.h)
 (action
  (run ./discover.exe)))

dune-project

(lang dune 2.8)
(name test-dune-configurator)

print_conf.ml

let () =
  Printf.printf "System has alsa: %d\n%!" (Test_dune_configurator.has_alsa ())

test_dune_configurator.c

#include <caml/misc.h>
#include <caml/mlvalues.h>
#include <caml/memory.h>

#include "config.h"

CAMLprim value ocaml_test_dune_configurator_has_alsa(value unit) {
  CAMLparam0();
#ifdef HAS_ALSA
  CAMLreturn(Val_int(1));
#else
  CAMLreturn(Val_int(0));
#endif
}

test_dune_configurator.ml

external has_alsa : unit -> int = "ocaml_test_dune_configurator_has_alsa"