std::DefaultConstructible

From cppreference.com
< cpplrm; | concepts
Defined in header <concepts>
template < class T >
concept DefaultConstructible = std::Constructible<T>;
(since C++20)

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)