fra: x+2? I don't see how that does anything. x += 2 maybye... And there should be a void rather than empty ().

I think the following illustrates it:

nrad@peregrine% cat test.c ~
int x;

int main(void)
{
x+2;
printf("%d\n",x);

return 0;
}

nrad@peregrine% gcc test.c -o test ~
nrad@peregrine% ./test ~
0

Infact, looking at the assembly it appears to have been seen as gcc (correctly) as a nothing instruction and optimized away.