23 Iterators library [iterators]

23.5 Iterator adaptors [predef.iterators]

23.5.7 Unreachable sentinel [unreachable.sentinels]

23.5.7.2 Comparisons [unreachable.sentinel.cmp]

template<WeaklyIncrementable I> friend constexpr bool operator==(unreachable_sentinel_t, const I&) noexcept; template<WeaklyIncrementable I> friend constexpr bool operator==(const I&, unreachable_sentinel_t) noexcept;
Returns: false.
template<WeaklyIncrementable I> friend constexpr bool operator!=(unreachable_sentinel_t, const I&) noexcept; template<WeaklyIncrementable I> friend constexpr bool operator!=(const I&, unreachable_sentinel_t) noexcept;
Returns: true.