Why GCC rejects std::optional for references?
<p><code>std::optional&lt;int&amp;&gt; xx;</code> just doesn't compile for the latest gcc-7.0.0 snapshot. Does the C++17 standard include <code>std::optional</code> for references? And why if it doesn't? (The implementation with pointers in a dedicated specialization whould cause no problems i guess.)</p>