std:: default_initializable

The default_initializable concept checks whether variables of type T can be

• value-initialized (i.e., whether T ( ) is well-formed);
• direct-list-initialized from an empty initializer list (i.e., whether T { } is well-formed); and
• default-initialized (i.e., whether T t ; is well-formed).

Access checking is performed as if in a context unrelated to T. Only the validity of the immediate context of the variable initialization is considered.

Possible implementation

template<class T>
concept default_initializable =
    std::constructible_from<T> &&
    requires { T{}; ::new T; };

References

See also