Variadic UNUSED function/macro

Question

A well-known and portable way to suppress C compiler warnings about unused variables is (see unused parameter warnings in C code):

#define UNUSED(x) (void)(x)
         


        

Answer 1

You can use compile time __VA_ARGS__ macro.

#define UNUSED(...) (void)(__VA_ARGS__)

UPDATE: After lot of trials, I came up to an optimized solution:

#define UNUSED(...)  __VA_ARGS__

int main()
{
    int e, x;
    char **a, **b, *c, d[45];
    x = x, UNUSED(a, b, c, d, e), x; 

    return 0;
}

NOTES:

1. It doesn't eliminate warnings completely but reduces them to just 3 same type of warnings:
   warning: value computed is not used

2. The first and last x ensure assignment of same datatypes.

3. I will say it is optimized because for any number of unused variables it gives 3 warnings (I may be wrong, please test it yourself and do report me if you get more) and the amount of code (MACRO manipulations) required to achieve it is less.

4. I am still working on it, will post if I reach to any better solution.