[Bug c/79959] -Wimplicit-fallthrough doesn't recognize some more complex exit cases

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79959

--- Comment #3 from Eric Gallager <egallager at gcc dot gnu.org> ---
(In reply to Marek Polacek from comment #2)
> Should be possible to fix this.  Mine.

For gcc 9?