[Bug c/81845] const union's field doesn't interpret as const in switch/case

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81845

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Aleksandr Slobodeniuk from comment #3)
> Fields of const-qualified structs and unions, that were initialized with
> const literals ARE *constant expressions*, isn't it?

No. See 6.6 p6