Alternative way to mark a noexcept function as not implemented

Question

I like to do this if I have only written an empty or partial implementation of a function:

... foo(...)
{
    // Some unfinished implementation or empty

    throw std::runtime_error("Not implemented.");
}

, so that I won't forget to complete the implementation before using it . And the code can compile and will work fine so long as I don't use it.

However, this will cause the compiler to give either a warning or an error if foo() has noexcept. Is there an alternative yet elegant way to achieve this?

Answer 1

You could always terminate the program:

#include <exception>
#include <iostream>
#include <source_location>

[[noreturn]] void Unimplemented(
    std::source_location caller,
    std::source_location called = std::source_location::current()) noexcept {
    std::cerr << "Unimplemented function\n"
              << called.file_name() << '(' << called.line()
              << "): " << called.function_name() << "\ncalled from\n"
              << caller.file_name() << '(' << caller.line()
              << "): " << caller.function_name() << '\n';
    std::terminate();
}

void foo(std::source_location loc = std::source_location::current()) noexcept {
    Unimplemented(loc);
}

int main() {
    foo(); 
}

Possible output:

Unimplemented function
/app/example.cpp(15): void foo(std::source_location)
called from
/app/example.cpp(19): int main()