Direct access warning in Xcode project-Collection of common programming errors

we are building an Xcode project and there are two warnings that I cannot figure out how to correct:

(null): Direct access in ___cxx_global_var_init36 to global weak symbol OFConditionConst::~OFConditionConst() means the weak symbol cannot be overridden at runtime. This was likely caused by different translation units being compiled with different visibility settings.

Has anyone else had to deal with this warning? Any help is greatly appreciated.