update OSX information in FAQ vignette

[romainfrancois]

specifically covering what should be done with Mavericks

[kevinushey]

We might reference this post from Ripley.

I suppose the main suggestion is as you had before: "set up your Makevars to use clang, and install Rcpp from source"

[romainfrancois]

Yes. Not sure what defense mechanisms will be put in next R releases to record clang and libc++ in R's Makeconf, but until then compile from source is the best shot.

[eddelbuettel]

When R is built, the values given to configure, eg via CC=abx CXX=def configure --option1 ... are stored in R's Makeconf. That needed to be explicit for g++-4.2 from XCode 4 which is why we have the old values pointing to nowhere. Folks can either edit in Makeconf, or supplant via their /.R/Makevars or env.vars.
Going forward, maybe @s-u can tell us what the values are going to be. He has always tried to support many releases so I am not sure how the XCode 4 / XCode 5 issue is best addressed.

[s-u]

There is no good answer - until R 3.1.0 (at least) you'll have to symlink the compilers or set the flags (personally, I prefer the former). Later, we may just go straight to clang, but that will mean dropping support of pretty much all old OS X versions - but it's inevitable.

[romainfrancois]

FWIW, there is no longer real good reasons not to use the latest OSX. It might have been the case when you had to pay for updates, except perhaps on really old machines. The majority of mac users run the latest version, therefore will have clang rather than llvm-gcc. This should be even more the case when R 3.1.0 is released.

A case of whether you (r core) want to facilitate backwards compatibility for a small portion of users and let the rest of the world do symlink or tweak a .R/Makevars or the opposite.

This has come up a few times in mailing lists and training sessions, it is not a big deal anyway to instruct people to recompile from source with a ~/.R/Makevars that sets CXX to clang++. So either way, this is not really a big deal.

[eddelbuettel]

Thanks @s-u -- your continued support of the variant OS X build flavours is appreciated. I have a few friends and colleagues who are somewhat conservative about upgrades. I'll put something along the lines of your comment into the Rcpp-FAQ next time I update it.

[s-u]

@romainfrancois you are wrong - the majority of users are still using OS X versions older than 10.9. In theory, they should upgrade - it's free after all - but apparently those damn users just don't feel like it. I agree that at some point in the future 10.9 will be in the majority, but it will take time. Also don't forget that R 3.0 was released long before 10.9 was available, so the next decision will be for R 3.1 so we'll have to see early next year if 10.9 is still in the minority by then (I suspect it may still be the case, unfortunately).

[coatless]

I'm pretty sure that for now this issue has been resolved with PR #433 and can be closed. (Tagged #506 )