@elextr Thanks for feedback.
I tried to use commands I seen during my compilation: ``` gcc -I"/usr/share/R/include" -DNDEBUG -fopenmp -fpic -O3 -mtune=native -c %f% ``` and it looks to work ``` gcc -I"/usr/share/R/include" -DNDEBUG -fopenmp -fpic -O3 -mtune=native -c "bmerge.c" (in directory: /home/jan/git/data.table/src) Compilation finished successfully. ``` The thing is that I am not getting real-time response about errors. I tried to put some code that uses an undeclared variable and no lines are getting marked as invalid. To spot the issue in the code I have to run compilation of the file again. Maybe I just expect to much and such a real-time response about invalid code is not among the features of Geany?