Well, the C++11 standard requires the Compiler to elide the copy (NRVO) if it wants to, or move if it doesn't want to. The language used is very lawyerish, I ha

Well, the C++11 standard requires the Compiler to elide the copy (NRVO) if it wants to, or move if it doesn't want to. The language used is very lawyerish, I had to read the section a couple of times to find it even though I knew it was there (it's mentioned in "Effective Modern C++"). So it's up to the compiler to elide the copy (making it a compiler optimisation as you say), but the standard says that it has to move if it doesn't elide. This means that returning a named loca variable by value is always the best choice. Again, see "Effective Modern C++" for more.