C++中的std::format 如何实现编译期格式检查

#include <format>
int a = 1;
std::string s1 = std::format("a: {}", a); // OK
std::string s2 = std::format("a: {}, b: {}", a); // 编译错误

#include <fmt/format.h>
int a = 1;
std::string s1 = fmt::format(FMT_STRING("a: {}"), a); // OK
std::string s2 = fmt::format(FMT_STRING("a: {}, b: {}"), a); // 编译错误

namespace my {
    template<class ...Args>
    class format_string {
    private:
        std::string_view str;
    public:
        template<class T>
            requires std::convertible_to<const T &, std::string_view>
        consteval format_string(const T &s)
            : str(s)
        {
            std::size_t actual_num = 0;
            for (std::size_t i = 0; i + 1 < str.length(); i++) {
                if (str[i] == '{' && str[i + 1] == '}') {
                    actual_num++;
                }
            }
            constexpr std::size_t expected_num = sizeof...(Args);
            if (actual_num != expected_num) {
                throw std::format_error("incorrect format string");
            }
        }
        std::string_view get() const { return str; }
    };
    template<class ...Args>
    std::string format(format_string<std::type_identity_t<Args>...> fmt, Args &&...args) {
        // 省略具体的格式化逻辑
    }
}