Containers of the standard template library (STL) can have non-copyable elements. The copy semantic is the fallback for the move semantic. Let’s learn more about the move semantic.

std::move

The function std::move moves its resource.

• The function needs the header <utility>.
• The function converts the type of its argument into a rvalue reference.
• The compiler applies move semantic to the rvalue reference.
• std::move is under the hood a static_cast to an rvalue reference.

static_cast<std::remove_reference<decltype(arg)>::type&&>(arg);

• What is happening here?
  • decltype(arg): deduces the type of the argument
  • std::remove_reference<....> removes all references from the type of the argument
  • static_cast<....&&> adds two references to the type

Copy semantic is a fallback for move semantic. This means if we invoke std::move with a non-moveable type, copy-semantic is used. This is due to the fact that an rvalue can be bound to an rvalue reference and a constant lvalue reference.