title: Does a vector assignment invalidate the `reserve`?
body: <p>Suppose I write</p>
  
  <pre><code>std::vector&lt;T&gt; littleVector(1);
  std::vector&lt;T&gt; bigVector;
  
  bigVector.reserve(100);
  bigVector = littleVector;
  </code></pre>
  
  <p>Does the standard say that <code>bigVector</code> will still have 100 elements reserved? Or would I experience memory reallocation if I were to <code>push_back</code> 99 elements? Perhaps it even varies between STL implementations.</p>
  
  <p>This was previously discussed <a href="https://stackoverflow.com/questions/2663170/stdvector-capacity-after-copying">here</a> but no Standard references were given.</p>