[Rd] CAR0 vs. EXTPTR_PTR

[William Dunlap]

I know that binary packages are R-version specific, but it was a bit
surprising that Rcpp 1.0.5 built with R-4.0.2 cannot be loaded into
R-4.0.0.

% R-4.0.0 --quiet
> library(Rcpp, lib="lib-4.0.2")
Error: package or namespace load failed for ‘Rcpp’ in dyn.load(file,
DLLpath = DLLpath, ...):
 unable to load shared object '/tmp/bill/lib-4.0.2/Rcpp/libs/Rcpp.so':
  /tmp/bill/lib-4.0.2/Rcpp/libs/Rcpp.so: undefined symbol: EXTPTR_PTR
In addition: Warning message:
package ‘Rcpp’ was built under R version 4.0.2

It looks like R's include/Rinternals.h was rejiggered so the function
EXTPTR_PTR is called when CAR0 used to be.   (I think they do the same
thing.)

Bill Dunlap
TIBCO Software
wdunlap tibco.com