[Bug c++/85827] false positive for -Wunused-but-set-variable because of constexpr-if

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85827

--- Comment #2 from Marc Glisse <glisse at gcc dot gnu.org> ---
I think that's going to be hard. The same issue always existed with macros. The
whole point of "if constexpr" is not to look at the other branches, as they may
not even compile. Sure, some minimal "safe" attempt at looking at those
branches would be possible, but I am not sure it is worth the trouble.