Can an official CRAN R package depend on Intel MKL and CMake? (and Check ?)

Question

In my R package I have C code that uses Intel MKL (and an open source library for C unit testing ). I use CMake to build the C code. I also have Rcpp interface code that I use to call the C code from R.

I wanted to know if CRAN would accept this package given that you'd have to have Intel MKL and CMake already installed on your system for it to work?

I'm not too worried about the unit testing, I can always get rid of that, but I definitely need Intel MKL because I'm using linear algebra routines that are specific to MKL eg Sparse-Matrix-Dense-Matrix multiply etc.

The reason I need CMake is because currently, that's what I'm using to build a static library from the C code and manipulate the Makevars file in the package's src folder, so that I can link the Rcpp interface code against the C library.

My Makevars looks as follows:

PKG_CPPFLAGS=-I/usr/local/lib/R/site-library/Rcpp/include -I/opt/intel/compilers_and_libraries_2019.4.243/linux/mkl/include -I./C
PKG_LIBS=-L./C/cmake-build-release -lbcd -llog -Wl,--start-group /opt/intel/compilers_and_libraries_2019.4.243/linux/mkl/lib/intel64/libmkl_intel_ilp64.a /opt/intel/compilers_and_libraries_2019.4.243/linux/mkl/lib/intel64/libmkl_sequential.a /opt/intel/compilers_and_libraries_2019.4.243/linux/mkl/lib/intel64/libmkl_core.a -Wl,--end-group -lpthread -lm -ldl 

This works on Ubuntu, but I'm worried about OS X and especially Windows. For example, here someone claims that Intel MKL is not compatible with minGW .

I know that there are many CRAN packages that use either MKL or CMake. But for the ones that I've investiaged, MKL is used as an optional BLAS library and CMake is used to build what's under the inst folder, which did not depend on external libraries. I've looked at writing R extensions and also the CRAN submission page but wasn't able to find find an answer. I thought that since there are more and more people interested in using CMake and MKL with R it would be good to have a SO post.

Answer 1

It seems you are tieing this up from the wrong end.

You have a more narrow and specialised solution you created (MKL, CMake).

Now you are worried that it may be too specialised. You are on the right path. First off, CMake is used by other packages so you could just declare it as a SystemRequirements: . Second, MKL is tougher but... also truly specialised.

Methinks the general recommendation for a broader CRAN upload would be to

• relax your code requirements: use MKL if present, but offer a fallback when not; now you no longer require MKL
• ditto for CMake: keep it and depend on it, better still try to not require it as most 15000 other CRAN package no not need it either.

Once you hit these two you're ready for a CRAN upload. If all this seems to onerous, just stick with a GitHub repository or maybe a drat repo.