xs/Roots_wrap.1.15.c:3283:7: error: void function '_wrap_gsl_root_fdfsolver_fdf_set' should not return a value [-Wreturn-type] return (gsl_nan()); ^ ~~~~~~~~~~~ ... xs/Roots_wrap.1.15.c:3840:7: error: void function '_wrap_gsl_root_fdfsolver_set' should not return a value [-Wreturn-type] return (gsl_nan()); ^ ~~~~~~~~~~~