[R-SIG-Mac] GCC v. LLVM

[Simon Urbanek]

On Mar 9, 2011, at 8:26 PM, Anirban Mukherjee wrote:

> Folks,
> 
> I was wondering what the forward plans are for R on Mac vis-a-vis
> apple-gcc/Clang. Xcode 4 was just released with LLVM 2.x.

For some definition of "released" - it's not really available to OS X users in general. For all practical purposes it's still a beta.


> From what I
> can tell, Apple will in the future only support Clang/LLVM. For now, I
> believe they are still including the same gcc as with 3.2. But longer
> term, the move seems to be to Clang/LLVM.
> 
> http://developer.apple.com/technologies/tools/whats-new.html
> http://clang.llvm.org/
> 
> Does R build with Clang/LLVM? I know Clang is being developed with a
> view to ensure GCC "compatibility".
> 

As Brian pointed out, R doesn't care. The only annoying part for me as a Mac binary maintainer is that it means Apple has abandoned the only branch that supported Fortran back-end, so in the future we will not be able to provide native Fortran for Xcode. This has been known for a while and Apple's stance is that they don't care about Fortran, so in some (but not immediate) future we may be back to the mess of mixing compilers.

Note that LLVM and clang don't really have any real benefits for the R users so far. Tests suggest that they make some parts slower and we could not measure any overall benefit (unlike let's say on arm), so people were not rushing to llvm/clang so far. Apple's move to llvm/clang is really based on a political decision, not a technical one. The only benefit I see so far is what Brian mentioned as well that some people will have to realize that gcc is not the standard and can test on other compilers to find their bugs.

Cheers,
Simon