https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117785
--- Comment #25 from Jakub Jelinek <jakub at gcc dot gnu.org> --- (In reply to Hana Dusíková from comment #1) > It's not part of the wording as CWG told me to take it out. But it's very > useful when an exception is not caught to call it's `.what()` and print > resulting message as part of the error. If there is no `.what()` available, > just print it structurally. In the end this is done only for classes derived from std::exception, to match e.g. the verbose terminate handler at runtime.