std::experimental::ranges::Regular
Min standard notice:
Header: <experimental/ranges/concepts>
The Regular concept specifies that a type is regular, that is, it is copyable, default constructible, and equality comparable. It is satisfied by types that behave similarly to built-in types like int, and that are comparable with ==.
# Declarations
template< class T >
concept bool Regular = Semiregular<T> && EqualityComparable<T>;
(ranges TS)