This blog is updated daily.
A general description is here.
‘R CMD INSTALL’ (and hence ‘check’) now by default compile C++ code with ‘-DR_NO_REMAP’. For the time being this can be reverted by setting environment variable ‘_R_CXX_USE_NO_REMAP_’ to a false value (but that will be removed in the near future).
`Writing R Extensions' has been revised to describe the remapped entry points, for with the ‘Rf_’ prefix remains optional when used from C code (but is recommended for new C code).