c++ - Not expected constructor called -

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i'm looking c++11 move constructors doesn't work. in fact issue before started writing such constructor. here's code snipped:

#include <iostream> #include <string> #include <sstream>  class object {     static std::ostream& log(object &obj) {         std::cout << "object::id = " << obj.mid << "::";          return std::cout;     }      unsigned mid = 0;     std::string *mtext = nullptr;      unsigned nextuniqueid() const {         static unsigned id = 0;         return ++id;     }      const std::string textinfo() const {         std::ostringstream oss;         oss << "mtext @ " << &mtext;         if (mtext) oss << " = " << *mtext;          return oss.str();     }  public:     object() = delete;     object& operator= (const object&) = delete;      explicit object(const std::string& str) : mid(this->nextuniqueid()), mtext(new std::string(str)) {         object::log(*this) << "constructor::one-argument\n";     }      object(const object& obj) : mid(this->nextuniqueid()), mtext(new std::string(*obj.mtext)) {         object::log(*this) << "constructor::copy\n";     }      virtual ~object() {         object::log(*this) << "destructor::" << this->textinfo() << "\n";         if (mtext) {             delete mtext;             mtext = nullptr;         }     } };  static object get_object() {     return object("random text"); }  int main(int argc, char **argv) {     object a("first object");  // ok      /*      * expected behaviour: inside get_object() function new object created   copied      * variable b. new id should given.      */     object b = get_object();  // hell?! not expected! why?      std::cout << std::endl;     return 0; }

the expected output similiar this:

object::id = 1::constructor::one-argument     object::id = 2::constructor::one-argument object::id = 2::destructor::mtext @ 0x7fff32c25f70 = random text object::id = 3::constructor::copy  object::id = 3::destructor::mtext @ <different in id=2> = random text object::id = 1::destructor::mtext @ 0x7fff32c25f90 = first object

i instead:

object::id = 1::constructor::one-argument object::id = 2::constructor::one-argument  object::id = 2::destructor::mtext @ 0x7fff32c25f70 = random text object::id = 1::destructor::mtext @ 0x7fff32c25f90 = first object

which looks variable b created on spot (something inline maybe?). frankly speaking don't know what's going on, can explain?

the compiler allowed apply "return value optimization" rvo , that's why copy optimized out. note standard allows despite side effects related output message


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