I'm trying to build my app with Xcode 9.0 beta 2 for iOS 11. The problem is the linker fails to find this __libcpp_debug_function definition. Do you have a workaround?
UPDATE: The project had _LIBCPP_DEBUG=0 preprocessor macro defined. When I remove it, it links successfully. Anyway, I still wonder why this linker error occurs when _LIBCPP_DEBUG=0 is defined.