The CPP-GL library provides an option to enable force inlining of seleced functions and methods in the implementation. This is defined through the gl_attr_force_inline macro, which by default is equivalent to the inline keyword.
To enable the force inlining functionality you have to add the following in your program:
#define GL_CONFIG_FORCE_INLINENote
Force inlining is supported only for the GNU G++ and CLang++ compilers.