https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126924
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> --- E.g. gcc/testsuite/c-c++-common/Wimplicit-fallthrough-13.c test tests exactly for this case and couple of similar (say fallthrough into case followed just by ; and end of switch body etc.). That test mentions https://web.archive.org/web/20160610055209/http://security.coverity.com/blog/2013/Sep/gimme-a-break.html as partial rationale (guess more discussions will be on the mailing list).
