| Friends | |
| template<typename I > requires weakly_incrementable<I> | |
| constexpr auto | operator!= (I const &, unreachable_sentinel_t) noexcept -> bool | 
| template<typename I > requires weakly_incrementable<I> | |
| constexpr auto | operator!= (unreachable_sentinel_t, I const &) noexcept -> bool | 
| template<typename I > requires weakly_incrementable<I> | |
| constexpr auto | operator== (I const &, unreachable_sentinel_t) noexcept -> bool | 
| template<typename I > requires weakly_incrementable<I> | |
| constexpr auto | operator== (unreachable_sentinel_t, I const &) noexcept -> bool |