https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81275
--- Comment #5 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #4)
> Marek, could we reuse the fallthrough warning infrastructure for this to
> determine whether there is a possible fallthrough or not?
> Though, trying:
> int
> foo (int a, int b, int c)
> {
> switch (c)
> {
> case 5:
> switch (a)
> {
> case 0:
> switch (b)
> {
> default:
> return 0;
> }
> break;
> #ifdef FT
> case 7:
> break;
> #endif
> default:
> return 0;
> }
> case 6:
> return 7;
> }
> return 8;
> }
>
> we don't warn about the fallthrough from case 5 to case 6 no matter if FT is
> defined (in that case there is obvious fallthrough, say for foo (7, 0, 5), or
> when FT is not defined (then there isn't, but gimple_seq_may_fallthru
> doesn't know that).
Unfortunately, not yet, because -Wimplicit-fallthrough doesn't scan nested
switches (PR79153).
