why move Constructor is not call?

Question

please look at the following example code:

    class testo
{
public:
    testo()
    {
        cout << " default " << endl;
    }

    testo(const testo & src)
    {
        cout << "copy " << endl;
    }
    testo(const testo && src)
    {
        cout << "move" << endl;
    }
    testo & operator=(const testo & rhs)
    {
        cout << " assigment" << endl;
        return *this;
    }
    testo & operator= (const testo && rhs)
    {
        cout << "move" << endl;
    }

};

and this is my function and main code :

testo nothing(testo & input)
{
return input;
}

int main ()
{
testo boj1 ;
testo obj2(nothing(obj1) );
return 1;
}

when i compile and run this code i expect to see :

default    // default constructor

copy       // returning from the function

move       // moving to the obj2

but when the code is getting execute it just show :

default 

copy

the compiler is Visual C++ 2015

Remove the const qualifier from your move constructor/move assignment — kreuzerkrieg, Apr 02 '17 at 05:15
Compiler am smart. It sees that the output of nothing can go right into `obj2` without any extra screwing around, so it does, building the copy on return right into the initialization of `obj2`. — user4581301, Apr 02 '17 at 06:52
Possible duplicate of [What are copy elision and return value optimization?](https://stackoverflow.com/questions/12953127/what-are-copy-elision-and-return-value-optimization) — underscore_d, Apr 17 '18 at 10:26

score 0 · Answer 1 · answered Apr 02 '17 at 05:19

0

Move signatures are supposed to be defined as T&&, not T const &&. While there's nothing in the language stopping you from declaring something T const &&, it makes no sense in practical terms: you mean to move from this object, but it's const and therefore can't have its state changed? It's a contradiction of terms.

answered Apr 02 '17 at 05:19

Xirema

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thank you for your answer but . removing the const keyword.. didn't helped – mehdi Apr 02 '17 at 06:06

why move Constructor is not call?

1 Answers1