std::vector<bool>::reference and std::bitset::reference
are both proxies, so even if they themselves are const, they can still be used to change the bit they reference.
Are there any issues?
IIUC, you're talking about Jonathan Wakely's P/R of
LWG 3638, and proposing that it should be amended to say
constexpr void flip()
const noexcept;
I would tend to agree with this suggestion (although `flip()` is a dumb member function to have, in general).
constexpr reference& flip() noexcept;
constexpr const reference& flip() const noexcept;