I hope I do not misunderstand your case, but I believe my experience with Image::DecodeQR::WeChat can help you (re: https://metacpan.org/pod/Image::DecodeQR::WeChat#IMPLEMENTATION-DETAILS). In that, I am linking against opencv library via a "normal" C program (C++ actually, but with C it is way simpler) wherein all my logic happens and calls to opencv's functions are placed. Then I create a very vanilla XS (you can copy-paste "mine" which already receives some input parameters and returns an arrayref of results back to perl code). Then place that intermediate C file in basedir of module. MM::EU will compile it. For distributing, just set the LIBS, CFLAGS, LDFLAGS in Makefile.PL to link to the compiled (DLL) C file and include that DLL somewhere in your distribution.

To recap: 0) forget Inline::C (though it is a *great* module). 1) create a vanilla XS file where you receive some params and return back results. That's documented and I climbed that learning curve ok-ish. In this XS, do not place any other program logic. Instead, 2) place all your program logic in a separate C file to be called via some functions. The benefit of this is that a) this C file will not be compiled along with Perl headers and all the problems usually occuring with macro-name clashes can be avoided, it is a perl-independent C file and b) in the C file, you are not constrained by XS idioms. 3) In XS just call the functions in your C file (and including appropriate C header file). A slight complication would be getting the XS function's (the one your Perl-code will call) input parameters and adjusting them for your C function calls. In my case I had to allocate memory and copy input parameters data into these and pass these to the C function, but that was my case. Also note that I arrived to above setup because including opencv function calls from within Inline::C or XS failed because opencv's headers contain macros and functions which clash with Perl's own name-sakes(!). If you don't have this constraint then your solution can be simpler. Bottomline is: vanilla XS with just a simple call to your C function which is implemented in its own C file in order to avoid any XS idioms and/or Perl header name clashes.

bw, bliako