Copy elision when creating object inside emplace()

Question

I see a lot of code at work where people use emplace and emplace_back with a temporary object, like this:

struct A {
    A::A(int, int);
};

vector v;
v         


        

Answer 1

I just want to add

There is a great 5 minutes lightning talk about copy elision and RVO from Jon Kalb https://youtu.be/fSB57PiXpRw

Also, you might get different results using different compilers gcc, clang or icc

See compiler explorer, try different compilers and settings and see for yourself

https://godbolt.org/g/Yjo9qA