There are many places where I might use Makevars or Makeconf to modify or overwrite the value of a variable used to configure compilation options in R.
I'd like to be able to see a list of all variables that are currently set, and their values.
Running R CMD config --all lists many, but not all, global values; for instance, DLLFLAGS is set in <R-version-path>/etc/<arch>/Makeconf but not included in this list.
Neither can I see a way to configure the config command to show the settings as they would apply within a given package, which may overwrite certain variables using local src/Makevars or src/Makevars.win files.
