Discussion on: Forbid a particular specialization of a template

#include <concepts>
#include <iostream>

template <typename T>
concept Number = (std::integral<T> || std::floating_point<T>) && (not std::same_as<T, bool>);

template <typename T> 
requires Number<T>
T f(T t) {
    return 2 * t + 3;
}

template <typename T> 
auto f2(T t) requires Number<T> {
    return 2 * t + 3;
}

template <Number T>
auto f3(T t) {
    return 2 * t + 3;
}

auto f4(Number auto t) {
    return 2 * t + 3;
}

int main () {
    std::cout << f(2) << std::endl;
    std::cout << f2(2.2) << std::endl;
    std::cout << f3(3) << std::endl;
    std::cout << f4(-2.4) << std::endl;
    // std::cout << f2(true) << std::endl; // auto f2(T) requires  Number<T> [with T = bool]' with unsatisfied constraints
}