compiler optimization

Question

So I have a question for you. :) Can you tell me the output the following code should produce?

#include 
struct Optimized
{
    Optimized() { std         


        

Answer 1

The output this code will produce is unpredictable, since the language specification explicitly allows optional elimination (elision) of "unnecessary" temporary copies of class objects even if their copy constructors have side effects.

Whether this will happen or not might depend on may factors, including the compiler optimization settings.

In my opinion calling the above copy elision an "optimization" is not entirely correct (although the desire to use this term here is perfectly understandable and it is widely used for this purpose). I'd say that the term optimization should be reserved to situations when the compiler deviates from the behavior of the abstract C++ machine while preserving the observable behavior of the program. In other words, true optimization implies violation of the abstract requirements of the language specification. Since in this case there's no violation (the copy elision is explicitly allowed by the standard), there's no real "optimization". What we observe here is just how the C++ language works at its abstract level. No need to involve the concept of "optimization" at all.