Optimizing away a “while(1);” in C++0x

Question

Updated, see below!

I have heard and read that C++0x allows an compiler to print \"Hello\" for the following snippet

#include 

        

Answer 1

The relevant issue is that the compiler is allowed to reorder code whose side effects do not conflict. The surprising order of execution could occur even if the compiler produced non-terminating machine code for the infinite loop.

I believe this is the right approach. The language spec defines ways to enforce order of execution. If you want an infinite loop that cannot be reordered around, write this:

volatile int dummy_side_effect;

while (1) {
    dummy_side_effect = 0;
}

printf("Never prints.\n");