base::Optional: Use anonymous union instead of base::AlignedMemory

styleguide/c++/c++11.html

Index: styleguide/c++/c++11.html
diff --git a/styleguide/c++/c++11.html b/styleguide/c++/c++11.html
index b44a0e4fed29c6fb7aff9f74b436b1e0be99f473..f9a0835b3b57f051b913596ce72f1685cc5f010f 100644
--- a/styleguide/c++/c++11.html
+++ b/styleguide/c++/c++11.html
@@ -287,6 +287,14 @@ template &lt;typename T&gt;<br/>void Function(T&& t) { ... }</code></td>
 </tr>
 
 <tr>
+<td>Union Class Members</td>
+<td><code>union <i>name</i> {<i>class</i> <i>var</i>}</code></td>
+<td>Allows class type members</td>
+<td><a href="http://en.cppreference.com/w/cpp/language/union">Union declarations</a></td>
+<td>Usage should be rare.</td>
+</tr>
+
+<tr>
 <td>Variadic Macros</td>
 <td><code>#define <i>MACRO</i>(...) <i>Impl</i>(<i>args</i>, __VA_ARGS__)</code></td>
 <td>Allows macros that accept a variable number of arguments</td>
@@ -679,14 +687,6 @@ work in all our compilers yet.</p>
 </tr>
 
 <tr>
-<td>Union Class Members</td>
-<td><code>union <i>name</i> {<i>class</i> <i>var</i>}</code></td>
-<td>Allows class type members</td>
-<td><a href="http://en.cppreference.com/w/cpp/language/union">Union declarations</a></td>
-<td></td>
-</tr>
-
-<tr>
 <td>User-Defined Literals</td>
 <td><code><i>type</i> <i>var</i> = <i>literal_value</i>_<i>type</i></code></td>
 <td>Allows user-defined literal expressions</td>