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copied!<p>(N)RVO is unrelated to the translation units. The term is commonly used to refer to two different copy elisions that can be applied one inside the function (from a local variable to the returned value) and by the caller (from the returned value to a local variable), and they should be discussed separately.</p> <p><strong>Proper RVO</strong></p> <p>This is performed strictly inside a function, consider:</p> <pre><code>T foo() { T local; // operate on local return local; } </code></pre> <p>Conceptually there are two objects, <code>local</code> and the returned object. The compiler can locally analyze the function and determine that the lifetime of both objects is bound: <code>local</code> only lives to serve as the source of a copy to the returned value. The compiler can then bind both variables in a single variable and use it.</p> <p><strong>Copy elision in the caller side</strong></p> <p>In the caller side, consider <code>T x = foo();</code>. Again there are two object, the returned object from <code>foo()</code> and <code>x</code>. And again the compiler can determine that the lifetimes are bound and place both objects on the same location.</p> <p>Further read: </p> <ul> <li><p><a href="http://definedbehavior.blogspot.com/2011/08/value-semantics-nrvo.html" rel="nofollow">Value semantics: NRVO</a></p></li> <li><p><a href="http://definedbehavior.blogspot.com/2011/08/value-semantics-copy-elision.html" rel="nofollow">Value semantics: Copy elision</a></p></li> </ul>

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