Question about F.41 and RVO (Return Value Optimiation)? about cppcoreguidelines HOT 2 CLOSED

To speak about RVO you need the following pattern:

my_class y = f();

my_class f()
{
    my_class result; //constructed directly inside y
    //...
    return result;
}

In the following code RVO is not relevant:

my_class y; //the default constructor of my_class is called
y = f(); //the temporary object returned by f is move-assigned to y

When you use tie, you need to write:

my_class my_object1;
my_class my_object2;
tie(my_object1, my_object2) = f();

my_object1 and my_object2 are already constructed before f() is called, so we cannot speak about RVO here.

But tie() will use move operators to put values inside my_object1 and my_object2. So no data will be copied unnecessarily even if my_class is a big type.

Eliyahu Ravuna

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@galik does this answer your question? Can this issue be closed now?

I don't think F.41 needs to be updated in anyway to cover anything.

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