https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69751
--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> --- (In reply to mgans...@alice.de from comment #0) > series.c:90:99: error: call of overloaded 'abs(size_t)' is ambiguous > if (::abs(strlen(evtCompShortText) - > strlen(episodeDb->getStrValue("COMPPARTNAME"))) >= dMin) > This doesn't do what the author of that code thinks it does. If the second string is longer than the first then the difference between them is not a negative number, it's a huge unsigned value. Calling abs(int) on a huge unsigned value will overflow and is undefined behaviour. This is exactly why calling abs() here should be an error: the code has undefined behaviour and should be fixed.