[R-SIG-Mac] XCode / gcc / R compatibility issues on Yosemite with XCode 7 and on El Capitan

[Jenny Brown]

I am maintaining R installations and packages for a large number of OS X
machines.  A recent change from Apple is making the R installation more
awkward, and I'm trying to determine the best path forward with minimal
maintenance headaches.


Recently, XCode 7's release on Yosemite 10.10 broke compilation of "brew
install --with-fortran gcc48" which is a pre-requisite for compiling third
party R packages that use fortran.  (XCode 7 eliminates the 10.9 and 10.10
SDKs and only provides 10.11 which is El Capitan's... so even though XCode
7 installs on Yosemite, it can not build for Yosemite, which causes gcc
trouble.  Lots of opensource devs are commenting on this on various
projects.)

It appears that the binary installs of R for OS X (3.1 through 3.2.2) were
all built against gcc 4.8.  I've discovered that gcc 5.2 builds properly on
Yosemite, even with XCode 7, and R can be compiled with gcc 5.2.

However, even the latest R (3.2.2) on cran.rstudio.com appears to be built
by default with gcc 4.8 -- are there plans to move to gcc 5.2?  Presumably
the breakage I'm seeing where gcc 4.8 can't use the xcode 7 10.11 SDK would
also occur on El Capitan, so gcc 5.2 would be a necessary upgrade there too.

Right now my choices for getting R to work with my third-party fortran
packages appear to be: manually downgrade xcode to 6.4 for Yosemite; or,
maintain my own compilation of R against gcc 5.2, for each of Yosemite and
El Capitan.  Both have their downsides, and I hope to be able to return to
the normal public binary R distribution sooner rather than later.

What's on the roadmap for upcoming upgrades and compatibility?  Thanks.

	[[alternative HTML version deleted]]