Sometimes it is good to print variable values to see what they are, but then GLM_FORCE_INLINE
has to be disabled.

I think it make sense to declare glm::to_string without inlining directive, as input/output operations are slow anyway. Then all the computation routines will be inlined and at the same time variables could be printed.

This is more of a suggestion, than an issue.

BTW, awesome library -- very nice and intuitive syntax. A lot of useful functions. Explicit access to members without annoying setters and getters crap, inlining + no constructor init if needed.