When should I use [[maybe_unused]]?

Question

What is good about using [[maybe_unused]]? Consider

int winmain(int instance, int /*prevInstance*/, const char */*cmdline*/, int show);

int win         


        

Answer 1

If the parameter is definitely unused, [[maybe_unused]] is not particularly useful, unnamed parameters and comments work just fine for that.

[[maybe_unused]] is mostly useful for things that are potentially unused, like in

void fun(int i, int j) {
    assert(i < j);
    // j not used here anymore
}

This can't be handled with unnamed parameters, but if NDEBUG is defined, will produce a warning because j is unused.

Similar situations can occur when a parameter is only used for (potentially disabled) logging.