return_const_value.cpp

#include <iostream>
#include <string>
#include <vector>

struct Foo {
  Foo() = default;
  Foo(const Foo &f) : s(f.s) {
    std::cout << "Copy constructor" << std::endl;
  }
  Foo(Foo &&f) : s(std::move(f.s)) {
    std::cout << "Move constructor" << std::endl;
  }

  std::string s;
};

Foo getFoo() {
  Foo f;
  return f;
}

const Foo getFooConst() {
  Foo f;
  return f;
}

int main() {
  std::vector<Foo> f;
  f.reserve(32); // avoiding reallocation at second push_back

  f.push_back(getFoo()); // call move constructor
  f.push_back(getFooConst()); // call copy constructor
  return 0;
}