This is likely an error installing PCRE2 (which I did using "sudo port install pcre2"), but when I "make" sample code for RInside, I get:
$ make rinside_sample0
clang++ -mmacosx-version-min=10.13 -std=gnu++11 -I/Library/Frameworks/R.framework/Resources/include -I/Library/Frameworks/R.framework/Versions/4.0/Resources/library/Rcpp/include -I/Library/Frameworks/R.framework/Versions/4.0/Resources/library/RInside/include -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk -Wall -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk -I/usr/local/include rinside_sample0.cpp -L/usr/local/lib -F/Library/Frameworks/R.framework/.. -framework R -L/usr/local/lib -lpcre2-8 -llzma -lbz2 -lz -licucore -ldl -lm -liconv -L/Library/Frameworks/R.framework/Resources/lib -lRblas -L/Library/Frameworks/R.framework/Resources/lib -lRlapack /Library/Frameworks/R.framework/Versions/4.0/Resources/library/RInside/lib/libRInside.a -o rinside_sample0
In file included from rinside_sample0.cpp:10:
In file included from /Library/Frameworks/R.framework/Versions/4.0/Resources/library/RInside/include/RInside.h:26:
In file included from /Library/Frameworks/R.framework/Versions/4.0/Resources/library/RInside/include/RInsideCommon.h:38:
In file included from /Library/Frameworks/R.framework/Versions/4.0/Resources/library/Rcpp/include/Rcpp.h:57:
/Library/Frameworks/R.framework/Versions/4.0/Resources/library/Rcpp/include/Rcpp/DataFrame.h:136:18: warning: unused variable 'data'
[-Wunused-variable]
SEXP data = Parent::get__();
^
1 warning generated.
ld: library not found for -lpcre2-8
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [rinside_sample0] Error 1
$
Thank you for the comment, Dirk. You got me pointed in the correct direction. I had two old versions of code: pcre2 and Rcpp.
I followed the directions for installing the latest version of "pcre2" here: https://izziswift.com/how-to-install-pcre-development-headers-on-mac-osx/.
I downloaded "pcre" version 10.39, cd'd to that directory, ran:
./configure
make
make install
After that, the examples in RInside compiled, but I got a runtime error:
$ ./rinside_sample0
Error: function 'Rcpp_precious_remove' not provided by package 'Rcpp'
Execution halted
$
Some searching showed that error arose from running an older version (1.0.6) of "Rcpp". I went into RStudio, typed "install.packages("Rcpp")" to update to version 1.0.7 and now everything runs!
Hopefully going through these steps will help anyone else who encounters these problems.