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I created an R package using RcppArmadillo from my Mac, and then built and installed it by doing the following:

Rcpp::compileAttributes()
devtools::build()
devtools::install()

However, I received several same warnings as below:

clang++ -std=gnu++11 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG  -I"/Library/Frameworks/R.framework/Versions/3.6/Resources/library/Rcpp/include" -I"/Library/Frameworks/R.framework/Versions/3.6/Resources/library/RcppArmadillo/include" -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk -I/usr/local/include  -fopenmp  -fPIC  -Wall -g -O2  -c RcppExports.cpp -o RcppExports.o
In file included from RcppExports.cpp:4:
In file included from /Library/Frameworks/R.framework/Versions/3.6/Resources/library/RcppArmadillo/include/RcppArmadillo.h:34:
In file included from /Library/Frameworks/R.framework/Versions/3.6/Resources/library/Rcpp/include/Rcpp.h:57:
/Library/Frameworks/R.framework/Versions/3.6/Resources/library/Rcpp/include/Rcpp/DataFrame.h:136:18: warning: unused variable 'data' [-Wunused-variable]
            SEXP data = Parent::get__();
                 ^
1 warning generated.

The package works fine although there are warnings during installation. Does anyone know how I can get rid of these warnings?

(I tried the answer here: Wunused-variable errors in Rcpp, but I still got the warnings.)

Olivia
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1 Answers1

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My previous (generic) StackOverflow answer (which you already referenced in your question) is still valid: Add the flag to CXXFLAGS (and maybe also CXX11FLAGS).

Alternatively, you can install an updated Rcpp version from the Rcpp Drat repo via

install.packages("Rcpp", repos="https://rcppcore.github.io/drat")

to get an Rcpp version with this fixes, and some other new versions. These fix will eventually make it into the CRAN version.

Edit: Here is a link to relevant announcement to the Rcpp mailing list.

Dirk Eddelbuettel
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  • Thanks a lot! The ```CXX11FLAGS``` one solved the issue. – Olivia Feb 01 '21 at 22:54
  • You're welcome! R itself controls these, and it's a bit tricky that values set for `CXXFLAGS` do not automagically promote to `CXX11FLAGS` (and same for C++14, C++17, ...) But at least now you know :) Also, of course: "warnings" are just "warnings", as annoying as they are. If you are _very_ confident in what you are doing you can also .... edit the header file :) – Dirk Eddelbuettel Feb 01 '21 at 23:32