检查编译器报错函数error(errno, ...)的入参，是否符合要求。

#include <string_view>
#include <type_traits>

// Exposition only
#define FAIL_CONSTEVAL throw

template <typename T>
struct Checker {
    consteval Checker(const char* fmt) {
        if (fmt != std::string_view{ "valid" }) // #1
            FAIL_CONSTEVAL;
        // T must be an int
        if (!std::is_same_v<T, int>)            // #2
            FAIL_CONSTEVAL;
    }
};

template <typename T>
void fmt(std::type_identity_t<Checker<T>> checked, T);

int main() {
    fmt("valid", 10);    // compiles
    fmt("oops", 10);     // fails at #1
    fmt("valid", "foo"); // fails at #2
}

https://devblogs.microsoft.com/cppblog/how-we-used-cpp20-to-eliminate-an-entire-class-of-runtime-bugs/
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