How to fix 'duplicate symbol' from importing h file in glm

Question

I'm currently working on a graphics project, and have come across an issue. I have two separate cpp files that both require the glm gtx extensions. The problem is, when both files #include "glm/ext.hpp", I get the following error: "duplicate symbol glm::floor_log2(unsigned int)".

I understand what the error means, and what is causing it (each compilation unit having its own version of the "glm::floor_log2(unsigned int)" function), but I don't understand how to get around it. Both files require access to the ext header, and will not compile without it (though together, they will not link).

How do I go about properly getting my project to compile and link?

Answer 1

As far as I can tell, the floor_log2 is declared in integer.hpp (without inline keyword), and defined in integer.inl (included from integer.hpp).

It is a bug in the glm source.

You should add inline to the declaration in integer.hpp (which will fix your problem) and notify developers of glm that they have a bug.