[Bug c++/66590] switch statement: incorrect warning "reaches end of non-void function"

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66590

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Related to bug 20681.  Most likely block_may_fallthru is returning true for the
{} block.