[Rcpp-devel] large number of warnings for simple use of Rcpp

Kevin Ushey kevinushey at gmail.com
Mon Nov 2 19:58:48 CET 2015

Hi Guillaume,

Compiling with the Makevars you provided, I see a number of warnings
related to sign conversion and loss of integer precision (due to the
use of `-Wconversion` in the Makevars).

I'll add an issue on the GitHub issue tracker just so we don't lose sight of it.


On Mon, Nov 2, 2015 at 10:48 AM, Guillaume Blanchet
<gblanchet.list at gmail.com> wrote:
> Hi !
> I apologie in advance if this question has already been answered but I have yet to find a solution to my problem.
> I recently started to learn Rcpp using the book « Seamless R and C++ Integration with Rcpp » by Dirk Eddelbuettel.
> Using the Fibonacci C code from the book, I tried to reproduce the example to get a feeling of how to work with Rcpp. More precisely, I wrote the following C code in a file that I called  « fibonacci.cpp ».
> #include <Rcpp.h>
> using namespace Rcpp;
> //[[Rcpp::export]]
> int fibonacci(const int x) {
>         if(x < 2){
>                 return(x);
>         }else{
>                 return fibonacci(x-1)+fibonacci(x-2);
>         }
> }
> Following, I called this file using the following command line:
> sourceCpp("fibonacci.cpp")
> What I get in return is a series of 80 warnings. Although, these warning may be helpful to answer this question, to keep this message concise I will not attached them here. However, if you feel they maybe helpful, let me know and I will send them along.
> Note that I am currently working on a Macbook Pro with the new OS (El Capitan). Following the advice given on the CRAN, I organized the Makevar file using clang as follow:
> CC=clang
> CXX=clang++
> CFLAGS=-mtune=native -g -O2 -Wall -pedantic -Wconversion
> CXXFLAGS=-mtune=native -g -O2 -Wall -pedantic -Wconversion
> FLIBS=-lgfortran
> Any reasons, why I get so many warnings ?
> Thanks in advance for your answer !
> Have a good day !
> Guillaume
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