Is it possible to ensure copy elision?

Question

Copy elision is a neat optimization technique and in some cases relying on copy elision can actually be faster than passing around references \"by hand\".

So, let\'s

Answer 1

In C++1z (expected 2017), some cases will be required to guarantee copy elision:

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/p0135r0.html

Per the communal cppreference.com compiler feature support wiki GCC 7+ and Clang 4+ ensure this.

The optimization side of this fortunately should not require enabling newer language support, since it's a pure optimization (following older language standard allowances).

Also allowing the copy constructor to be unavailable when the optimization applies probably will require the newer language standard to be enabled during compilation, or use of a loose or extended mode that doesn't demand strict conformance (e.g. potentially GCC's -fpermissive).