G++ error from previous declaration, error due to duplicate function name in includes

Question

I am writing a Rcpp code that include two library RcppArmadillo and trng4. However, when I include two header files (RcppArmadillo.h and trng/gamma_dist.hpp) it gives compilation error.

 trng/special_functions.hpp:47:39: error: declaration of ‘float lgammaf(float) throw ()’ has a  different exception specifier
 extern "C" float lgammaf(float) throw();
include-fixed/math.h:476:14: error: from previous declaration ‘float lgammaf(float)’
extern float lgammaf(float);

Full compilation options are

-fopenmp -lgomp -DUSE_R -DNDEBUG -DDISABLE_SINGLE -DNTHROW -DDISABLE_FIO -I/usr/local/include -I"/Users/avi/Library/R/3.0/library/Rcpp/include" -I"/Users/avi/Library/R/3.0/library/RcppArmadillo/include"   -fPIC -pipe -std=c++0x -Wall -pedantic -c 

Seems like the lgammaf is declared in both header files. I tried using -E with g++ option but that give ld warning " .o, file was built for unsupported file format" and give error function in not available in .Call when I try it to after loading in R. What am I doing wrong?

Perhaps out of context I am using trng4 package to develop a thread gibbs sampler (in openmp) that sample from gamma distribution. I am currently running this MacOS. But eventual it will run in linux server.

Answer 1

It sounds like you do have a problem between Armadillo and trng4. Maybe you should try to, if possible, separate your interface so that you do not need to include from both in the same file.

Answer 2

Someone can correct me if I'm wrong, but I believe you prevent this issue by using #ifndef in each header file so that it's not defined a second time even if it's included a second time. But I guess these aren't your files are they...?

#ifndef __your_unique_header_name__

blah blah


#endif