[R-SIG-Mac] building 32-bit version of R 3.x

[Simon Urbanek]

On Mar 3, 2014, at 3:41 PM, Alexy Khrabrov <deliverable at gmail.com> wrote:

>> They are both installed into the same "fat" framework. Everything is shared (i.e. files exist only once) except for the .so objects and some configurations that are in separate subdirectories based on the r_arch setting. OS X supports multiple architectures in one binary, that's why you don't need to modify any paths. OS X was running several architectures in parallel for a long time (first PPC+Intel then ppc+ppc64+i386+x86_64) so it "just works". The only thing to remember is that when you are compiling 3rd party dependencies, you must compile them "fat" for both architectures as well (or use lipo to combine them).
> 
> Great -- so how should I configure R build to do that?  Obviously the
> above builds only one.
> 

You always build one, but they both install into one merged framework. You choose which to invoke by setting the --arch parameter, e.g. R --arch=x86_64 to run the 64-bit version. The default will be whichever you install last.

Cheers,
Simon