How to link with static libraries when building an R package...

Answer 1

I've not tried doing this with C/C++ but rather with Fortran. I had a similar problem in that some standard IO libraries weren't being included in the library I was created. In the end I just included them all and compiled using the Fortran compiler. I didn't use any of the R compiler utilities, just compiled as if I were compiling a static Fortran library normally for use with anything else. This worked fine.

A debug path might be to compile as a static library using gcc (or whatever you're using) then try to include and call that static library from another C program, then if that works try with R.

Hope this is helpful, writing these R packages is pretty hard unless you're using vanilla C or Fortran as far as I can tell.