Is it best practice to assign a std::vector<T> to a variable before iteration?

I’m working with a smart pointer which returns a std::vector<T> over which I want to iterate using a for loop.

Are there any disadvantages to returning the std::vector<T> directly within the for loop as opposed to assigning it to a variable before the loop?

For example, instead of this:

const myClass& vec = myPtr->getVec();
for (const itemPtr& item : vec)
{
    ...
}

Can I safely do this?:

for (const itemPtr& item : myPtr->getVec())
{
    ...
}

>Solution :

In fact, a binding to a reference is part of declared range for-loop functionality, only it uses an rvalue reference (result could have been a temporary):

//for ( init-statement (optional) range-declaration : range-expression )
//   loop-statement

{
  init-statement
  auto && __range = range-expression ;
  auto __begin = begin-expr ;
  auto __end = end-expr ;
  for ( ; __begin != __end; ++__begin)
  {
    range-declaration = *__begin;
    loop-statement
  }
}