Ok, so I got the with-c example to build by running -configure before I
built with ocaml setup.ml -build, and that worked. But then there's a part
in there where ocamlbuild is passed a libwith-c_stubs.a target and it knows
what to do with it. I've tried to copy that example line by line in my
_oasis and command line steps, and I have know what calls ocamlbuild should
be making to get the .cma and .cmxa targets. But I can't get my _oasis to
work.

On Sun, Aug 27, 2017 at 1:19 AM, Kenneth Adam Miller <
kennethadammiller@gmail.com> wrote:

> Actually, I think it's that ocamlbuild should be told to link
> libdai_stubs.a, and not try and build it. But also, I wanted to reference
> an existing work that links with C libraries, and I found ocamlbuild's
> example, with-c. I tried to build it, and I found that it isn't built by
> the harness default. Also, if you just try and build within just that raw
> directory in isolation, that it fails with a similar error I had been
> getting earlier. I looked around and found these:
>
> https://stackoverflow.com/questions/19644451/how-to-
> make-ocamlbuild-compile-and-link-a-c-file-into-an-ocaml-project
> https://l-lang.blogspot.com/2012/08/incorporating-c-code-
> in-ocaml-project.html
> https://ocaml.org/learn/tutorials/ocamlbuild/Using_an_
> external_library.html
>
> And I'm trying to follow, but they each give unique directions, each seem
> to not work for me.
>
> On Sat, Aug 26, 2017 at 9:12 PM, Kenneth Adam Miller <
> kennethadammiller@gmail.com> wrote:
>
>> Hello,
>>
>>
>> I'm building a pair of companion oasis build spec and opam package setup
>> for a C library. libdai I figured out how to get swig and oasis to build
>> most things I need, but I'm having trouble getting oasis to not generate
>> _stubs targets that aren't found. There is a static C/++ libdai.a file that
>> is the product of the project I'm trying to wrap. I can't convince oasis to
>> use that instead. Here's my _oasis target:
>>
>>
>> Library "dai"
>>   Path:                 ./
>>   Install:              false
>>   Modules:              Swig, Dai
>>   CompiledObject:       best
>>   CSources:             dai_wrap.cxx.c
>>   CCOpt:                -g -xc++ "-I../../include"
>>
>>
>> With a fresh clone of libdai, I get dai_wrap.cxx.c by doing the following
>> in ./swig after building libdai:
>>
>> $(SWIG) -ocaml -c++  dai.i
>> mv dai_wrap.cxx dai_wrap.cxx.c
>> sed -i -e 's/caml_array_length/caml_array_len/g' dai_wrap.cxx.c
>>
>> I got my swig and dai ml files by doing the following:
>>
>> swig2.0 -ocaml -co dai.ml
>> swig2.0 -ocaml -co swig.ml
>> swig2.0 -ocaml -co swig.mli
>>
>> I build by doing the following:
>>
>> ocaml setup.ml -configure
>> ocaml setup.ml -build
>>
>>
>> I get the following error:
>>
>>
>> Solver failed:
>>   Ocamlbuild knows of no rules that apply to a target named
>> ./libdai_stubs.a. This can happen if you ask Ocamlbuild to build a target
>> with the wrong extension (e.g. .opt instead of .native) or if the source
>> files live in directories that have not been specified as include
>> directories.
>> Compilation unsuccessful after building 8 targets (8 cached) in 00:00:00.
>> E: Failure("Command ''/usr/bin/ocamlbuild' ./libdai_stubs.a
>> ./dlldai_stubs.so ./dai.cma ./dai.cmxa ./dai.a ./dai.cmxs -j 5 -tag debug'
>> terminated with error code 6")
>>
>> I want to make sure that the actual target shared library that was
>> produced by the libdai build file itself is linked against. But oasis is
>> assuming I have a _stubs target. I read in the documentation here that: "The
>> usual idiom is to append _stubs to the name."
>> https://ocaml.org/learn/tutorials/setting_up_with_oasis.
>> html#Interfacing-with-C-code
>>
>> And I think that that is the source of the error, but it isn't well
>> explained. The ultimate things I originally wanted was to be able to use
>> libdai with both the utop or the bytecode interpreter and with fully
>> compiled targets. I was going to make libdai a library and then publicize
>> it.
>>
>> If anybody needs to replicate my issue, I have a docker container with
>> this already.
>>
>
>