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    <p>The implicit generation of move constructors and assignment operators has been contentious and there have been major revisions in recent drafts of the C++ Standard, so currently available compilers will likely behave differently with respect to implicit generation.</p> <p>For more about the history of the issue, see <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/" rel="noreferrer">the 2010 WG21 papers list</a> and search for "mov"</p> <p>The current specification (N3225, from November) states (N3225 12.8/8):</p> <blockquote> <p>If the definition of a class <code>X</code> does not explicitly declare a move constructor, one will be implicitly declared as defaulted if and only if </p> <ul> <li><p><code>X</code> does not have a user-declared copy constructor, and </p></li> <li><p><code>X</code> does not have a user-declared copy assignment operator, </p></li> <li><p><code>X</code> does not have a user-declared move assignment operator, </p></li> <li><p><code>X</code> does not have a user-declared destructor, and </p></li> <li><p>the move constructor would not be implicitly defined as deleted. </p></li> </ul> </blockquote> <p>There is similar language in 12.8/22 specifying when the move assignment operator is implicitly declared as defaulted. You can find the complete list of changes made to support the current specification of implicit move generation in <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3203.htm" rel="noreferrer">N3203: Tightening the conditions for generating implicit moves </a>, which was based largely on one of the resolutions proposed by Bjarne Stroustrup's paper <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3201.pdf" rel="noreferrer">N3201: Moving right along</a>.</p>
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    1. POWhy no default move-assignment/move-constructor?
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    1. USJames McNellis
    1. USJames McNellis
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    1. POWhy no default move-assignment/move-constructor?
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    1. COI wrote a small article with some diagrams describing the relationships for implicit (move)constructor/assignment here: http://mmocny.wordpress.com/2010/12/09/implicit-move-wont-go/
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    2. COUgh so whenever I have to define blank destructors in polymorphic base classes just for the sake of specifying it as virtual, I have to explicitly define the move constructor and assignment operator as well :(.
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    3. CO@someguy: `virtual ~D() = default;` should work.
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      1. USJames McNellis
 

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