The issues I have had with R 3.4.0 RC appear to have mostly been resolved macOS
(release candidate r72556 from http://r.research.att.com)
Many packages using Rcpp now do link to the libc++.1.dylib in the R framework.
The following packages using Rcpp that I have installed are still linking to
That's 20 out of the 43 packages using Rcpp that I have installed.
I have not checked all available packages using Rcpp.
I always install binary packages.
I don't really or urgently need to have clang4 installed so I would prefer all
C++ using packages to link to the libc++.1.dylib in the R framework.
The private package I referred to in previous mails works fine with Apple's
R-SIG-Mac mailing list