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    <p>You need to inform C++ (specifically <code>std::vector</code>) that your move constructor and destructor does not throw, using <code>noexcept</code>. Then the move constructor will be called when the vector grows. </p> <p>This is how to declare and implement a move constuctor which is respected by <code>std::vector</code>:</p> <pre><code>A(A &amp;&amp; rhs) noexcept { std::cout &lt;&lt; "i am the move constr" &lt;&lt;std::endl; ... some code doing the move ... m_value=std::move(rhs.m_value) ; // etc... } </code></pre> <p>If the constructor is not <code>noexcept</code>, <code>std::vector</code> can't use it, since then it can't ensure the exception guarantees demanded by the standard.</p> <p>For more about what's said in the standard, read <a href="https://stackoverflow.com/questions/4732084/c-move-semantics-and-exceptions">C++ Move semantics and Exceptions</a> </p> <p>Credit to Bo who hinted that it may have to do with exceptions. Also consider Kerrek SB's advice and use <code>emplace_back</code> when possible. It <em>can</em> be faster (but often is not), it can be clearer and more compact, but there are also some pitfalls (especially with non-explicit constructors).</p> <p><strong>Edit</strong>, often the default is what you want: move everything that can be moved, copy the rest. To explicitly ask for that, write </p> <pre><code>A(A &amp;&amp; rhs) = default; </code></pre> <p>Doing that, you will get noexcept when possible: <a href="https://stackoverflow.com/questions/18653726/is-the-default-move-constructor-defined-as-noexcept">Is the default Move constructor defined as noexcept?</a></p> <p>Note that early versions of Visual Studio 2015 and older did not support that, even though it supports move semantics.</p>
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    1. POHow to enforce move semantics when a vector grows?
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    1. USJohan Lundberg
    1. USJohan Lundberg
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    1. CONote: `throw()` is deprecated, use `noexcept` instead.
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      1. USMatthieu M.
    2. CO@MatthieuM. Ah, yes - fixed that now. Well spotted.
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      1. USJohan Lundberg
    3. COOut of interest, how _does_ the impl "know" whether the `value_type`'s move ctor is `noexcept`? Perhaps the language restricts the function call candidate set when the calling scope is also a `noexcept` function?
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      1. USLightness Races in Orbit
 

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