compiling armadillo with Rtools/MinGW

Question

I'm trying in vain to compile the armadillo linear algebra library for windows. Using the armadillo-4.200.0 source, I have Rtools-3.1 installed and in the path, msys from MinGW installed.

Because my ultimate goal is to use Rcpp and RcppArmadillo, my thought is that I need to use the same compiler for making armadillo as will be used to compile my Rcpp/RcppArmadillo files. Unfortunately, when trying to compile armadillo:

$ ./configure
[...snip...]
-- The CXX compiler identification is unknown
-- Check for working CXX compiler: cl
CMake Warning at CMakeLists.txt:3 (PROJECT):
  To use the NMake generator, cmake must be run from a shell that can use the
  compiler cl from the command line.  This environment does not contain
  INCLUDE, LIB, or LIBPATH, and these must be set for the cl compiler to
  work.

CMake Error: your CXX compiler: "cl" was not found.   Please set CMAKE_CXX_COMPILER to a valid compiler path or name.
[...snip...]

(I tried setting CMAKE_CXX_COMPILER to my Rtools gcc.exe with no luck.)

I believe that it is looking for the visual C compiler, though the docs imply that it can be done solely with the mingw or cygwin compiler environments.

Either:

1. Is there a problem with compiling the armadillo library and subsequent Rcpp code with different versions of the compiler? (Rtools-3.1 has gcc version 4.6.3, MinGW has gcc version 4.8.1.)

2. Is there a clean method for compiling armadillo with just the Rtools collection?

(Win7 x64, R-3.1.0, cygwin gcc 4.8.2, rtools 3.1 with gcc 4.6.3.)

Answer 1

RcppArmadillo ships its own copy of Armadillo to avoid exactly this problem. As RcppArmadillpo is used from R, it can rely on R (and R's configuration) to get LAPACK, BLAS, etc pp. We don't need to run configure to use Armadillo from R, and so we don't do.

RcppArmadillo installs the usual R CMD INSTALL ... way; this is tested before every release and has worked reliably.

As you say "your ultimate goal is to use Rcpp and RcppArmadillo", you are in fact done at the R CMD INSTALL .... You can replicate the step from source, and test the package -- all that should "just work".

The other thing to keep in mind is what the "Writing R Extensions" and "R Installation and Administration" manuals have to say about your compiler. As far is R is concerned, your g++ 4.8.* does not exist. Only the Rtools version matters, or you get into non-standard land real quick.