Building C++ code with ocamlbuild
c++, ocaml, ocamlbuild
Solution
cf. my answer to the similar question.
I recommend the following approach :
- name c++ files with `.c` extension so that `ocamlc` picks them up
- tell `gcc` that those are actually c++ files with `-x c++`
- tell `ocamlbuild` that the build actually depends on `.h` files (e.g. list `.h` files together with `.c` in the `CSources` field in `_oasis`)
- do not forget to link `-lstdc++` explicitely cause `gcc` will not do that being a C compiler it is
- use cxx_wrapped.h to get that real C++ feel
- PROFIT!!
See hypertable bindings as an example of this approach.
Problem
I have found many guides on how to build `.o` files from C sources using `ocamlbuild`. These do not apply to C++ files, however, which `ocamlbuild` cannot build out of the box. I have tried writing a `myocamlbuild.ml` file (shown below after request) providing a rule from `.cpp` to `.o` and that fails with `ocamlc` complaining that it does not know what to do with a `.cpp` file (even when the compiler is set to `g++` via command line flags). ``` open Ocamlbuild_plugin ;; let ext_obj = !Options.ext_obj;; let x_o = "%"-.-ext_obj;; rule "ocaml C++ stubs: cpp -> o" ~prod:x_o ~dep:"%.cpp" begin fun env _build -> let c = env "%.cpp" in let o = env x_o in let comp = if Tags.mem "native" (tags_of_pathname c) then !Options.ocamlopt else !Options.ocamlc in let cc = Cmd(S[comp; T(tags_of_pathname c++"c"++"compile"); A"-custom"; A"-cc"; A"g++"; A"-c"; Px c]) in if Pathname.dirname o = Pathname.current_dir_name then cc else Seq[cc; mv (Pathname.basename o) o] end;; ``` The file `libsoundness.clib` consists of a bunch of `.o` files. When I do `ocamlbuild libsoundness.a` I get the following output: ``` Finished, 0 targets (0 cached) in 00:00:00. + /usr/bin/ocamlc.opt -custom -cc g++ -c src/soundness/proof_aut.cpp /usr/bin/ocamlc.opt: don't know what to do with src/soundness/proof_aut.cpp. Usage: ocamlc <options> <files> <snipped long list of ocamlc options> ``` The only other solution for C++ seems to be `ocamlbuild-ctools` whose website is defunct (I could not download any sources). Any ideas?