std::integral

template< class T >
concept integral = std::is_integral_v<T>;

#include <concepts>
#include <iostream>
 
void print(std::integral auto i)
{
    std::cout << "Integral: " << i << '\n';
}
 
void print(auto x)
{
    std::cout << "Non-integral: " << x << '\n';
}
 
int main()
{
    std::cout << std::boolalpha;

    static_assert(std::integral<bool>);
    print(true);

    static_assert(std::integral<char>);
    print('o');

    static_assert(std::integral<int>);
    print(007);

    static_assert( ! std::integral<double> );
    print(2e2);

    static_assert( ! std::integral<decltype("")> );
    print("∫∫∫");
}

Output:

Integral: true
Integral: o
Integral: 7
Non-integral: 200
Non-integral: ∫∫∫