What's a C++03 compliant way of fetching a value from a volatile variable?

Question

According to this defect report C++03 Standard does not guarantee that in the following code:

volatile int x;
void f() {
    x;
}

the variable is read from.

Then how do I write code that just read the volatile variable value and discards the result (read for the sake of read)?

Answer 1

int i = x; should work. This code absolutely requires reading the volatile variable and the optimizer is not allowed to optimize the read away. But since the variable i is unused the optimizer can avoid any extra work involved in storing the read value.

You might also need something like this to avoid compiler warnings: (void)i;