21 Language support library [language.support]

21.8 Exception handling [support.exception]

21.8.5 uncaught_­exceptions [uncaught.exceptions]

int uncaught_exceptions() noexcept;
Returns: The number of uncaught exceptions ([except.uncaught]).
Remarks: When uncaught_­exceptions() > 0, throwing an exception can result in a call of
std​::​terminate() ([except.terminate]).