Is std::move really needed on initialization list of constructor for heavy members passed by value?
- by PiotrNycz
Recently I read an example from cppreference.../vector/emplace_back:
struct President
{
std::string name;
std::string country;
int year;
President(std::string p_name, std::string p_country, int p_year)
: name(std::move(p_name)), country(std::move(p_country)), year(p_year)
{
std::cout << "I am being constructed.\n";
}
My question: is this std::move really needed? My point is that compiler sees that this p_name is not used in the body of constructor, so, maybe, there is some rule to use move semantics for it by default?
That would be really annoying to add std::move on initialization list to every heavy member (like std::string, std::vector). Imagine hundreds of KLOC project written in C++03 - shall we add everywhere this std::move?
This question: move-constructor-and-initialization-list answer says:
As a golden rule, whenever you take something by rvalue reference, you
need to use it inside std::move, and whenever you take something by
universal reference (i.e. deduced templated type with &&), you need to
use it inside std::forward
But I am not sure: passing by value is rather not universal reference?
