[R-SIG-Mac] Tools Update for R3.5?

[Roger Koenker]

I’ve just installed R3.5 and clang6 and fortran 6.1 and now realize that the compiler packages install in
/usr/local/clang6 and /usr/local/gfortran  respectively.  I expected that there would also be some automatic
symbolic links to /usr/local/bin  etc.  however when I tried to compile packages from source the old versions
of the compilers are invoked.  I realize that this is probably quite elementary, but I would appreciate some
advice on how to complete the installation so the new compilers are accessed.

Many thanks,
Roger