21 Language support library [language.support]

21.8 Exception handling [support.exception]

21.8.5 uncaught_Β­exceptions [uncaught.exceptions]

int uncaught_exceptions() noexcept;

Returns: The number of uncaught exceptions.

Remarks: When uncaught_Β­exceptions() > 0, throwing an exception can result in a call of std​::​terminate().