std::experimental::ranges::DefaultConstructible

From cppreference.com
< cpplrm; | experimentallrm; | ranges
template < class T >
concept bool DefaultConstructible = Constructible<T>;
(ranges TS)

The DefaultConstructible concept provides a shorthand for the common case when the question is whether a type can be constructed with no arguments.

See also

specifies that a variable of the type can be constructed from or bound to a set of argument types
(concept)
checks if a type has a default constructor
(class template)