Question

I have a function which looks something like this, it returns a noncopyable class by movesemantics:

MyClass&& MyFunction() {
  MyClass myClass;
  do some stuff;
  return std::move(myClass);
}

And then it’s accessed by

main() {
  MyClass myClass = MyFunction();
}

The class utilizes boost::noncopyable for copyprevention. It has constructor, move constructor and move assignment.
My problem is, the destructor gets called before the move constructor. What have I done wrong?

Answer 1

You are returning a reference to a local variable. It doesn’t matter if it is an lvalue reference or an rvalue reference.

You probably should just do

MyClass MyFunction() {
  MyClass myClass;
  do some stuff;
  return myClass;
}

and let the compiler figure out how to copy or move the result.