Compiling R from source on a Mac

I recently needed to run R devel on a Mac and couldn’t get the precompiled binaries to work (ggplot2 would segfault when I tried to install it – probably a compiler issue). In any case, R is pretty quick to compile from source (at least in terms of wall clock), though there ended up being quite a few Mac-specific issues to tackle.

1. Install clang8 or greater, eg here or perhaps with homebrew.
2. export SDKROOT="$(xcrun --sdk macosx --show-sdk-path)" so clang can find headers that Apple puts in a weird place. Consider adding this to .bash_profile, and potentially .Renviron (I need to logout and back in to test if this is necessary). This was the weirdest and hardest to solve problem.
3. Download R sources, unpack.
4. Edit config.site following instructions in the R installation and Administration guide, especially those about setting variables CC, CXX and R_LD_LIBRARY_PATH to point to where your upgraded version of clang lives. Somehow, after installation, R will magically know to continue to use these compilation variables for all libraries that are installed!
5. Run ./configure setting at least --enable-memory-profiling --enable-R-framework --x-libraries=/opt/X11/lib if you want to be able to run RStudio against your compiled R. I also set --with-blas="-framework Accelerate", and you could try to set --enable-lto if you have clang10 (?) or higher for a potential speed-up.
6. make; make install if you set --enable-R-framework. You will probably need sudo for make install, and might need to set SDKROOT again if you get complaints about missing headers. If you didn’t --enable-R-framework, then consider make install rhome=/usr/local/lib/R-4.0.0-devel since setting rhome to be something non-default will let multiple versions coexist.