What happens to unused function return values?

Question

If I have a program:

#include 

using namespace std;

int TestIntReturn(int &x, int &y)
{
    x = 1000;
    y = 1000;
    return x+y;         


        

Answer 1

It is discarded; the expression TestInReturn(a,b) is a discarded-value expression. Discarding an int has no effect, but discarding a volatile int (or any other volatile-qualified type) can have the effect of reading from memory.