How to write a concept that requires one to create an object to specify that that constructor must exist

[JUANDENT]

I need to write the following concept:

template<typename T>
concept Element = requires (T a, T b)
{
	a = b;
	T c{ a };
};

I know I can do

requires std::is_copy_constructible_v<T>;

but I want to create an object of type T inside the concept!


So I can check for other things, e.g.'

template<typename T>
concept Element = requires (T a, T b, int i)
{
	a = b;
	T c{ a };
        T d{i};
};