std::sorted_equivalent_t, std::sorted_equivalent

From cppreference.com
< cpp‎ | container
Defined in header <flat_map>
Defined in header <flat_set>
struct sorted_equivalent_t { explicit sorted_equivalent_t() = default; };
(1) (since C++23)
inline constexpr sorted_equivalent_t sorted_equivalent{};
(2) (since C++23)
1) The type std::sorted_equivalent_t can be used in the function's (including constructor's) parameter list to match the intended tag.
2) The corresponding std::sorted_equivalent instance of (1) is a disambiguation tag that can be passed to the functions of std::flat_multimap and std::flat_multiset to indicate that the input range or container is sorted (with respect to the comparator used in flat container adaptor), whilst uniqueness of elements is not required.

Standard library

The following standard library container adaptors use (1,2) as disambiguation tags:

adapts two containers to provide a collection of key-value pairs, sorted by keys
(class template)
adapts a container to provide a collection of keys, sorted by keys
(class template)

See also

indicates that elements of a range are sorted and unique
(tag)
from-range construction tag
(tag)
in-place construction tag
(tag)