multiple definition of `R_running_as_main_program`

I inherited a C++ application that was using rcpp to embed R. After R was upgraded to 3.2, the make was failing miserably with the error:

file1.o:(.bss+0x0): multiple definition of `R_running_as_main_program'
file2.o:(.bss+0x0): first defined here

This was found to be caused by https://bugs.r-project.org/bugzilla3/show_bug.cgi?id=15899

To overcome this, edit /usr/share/R/include/Rinterface.h and search for this line:

int R_running_as_main_program;

Add the “extern” keyword at the start and save it:

extern int R_running_as_main_program;

After that there should be no problem building the program.