This check in some of the add-ons:
#ifdef AS_CAN_USE_CPP11
#include <chrono>
#else
#error Sorry, this requires C++11 which your compiler doesn't appear to support
#endif
Causes warnings about there being a missing ' character:
/home/hhyyrylainen/Projects/leviathan/libraries/include/add_on/datetime/datetime.h:12:60: varoitus: päättävä merkki ' puuttuu
#error Sorry, this requires C++11 which your compiler doesn't appear to support
^
This is nothing major, but it does cause annoying warnings when rebuilding files that include the add-on headers.