constexpr defaulted default constructors
<p>I get compiler error by Clang 3.8 and GCC 5.3 if I want to declare my <code>default</code>-ed default constructors as <code>constexpr</code>. According to <a href="https://stackoverflow.com/questions/20810378/should-i-mark-a-compiler-generated-constructor-as-constexpr">this</a> stackoverflow question it just should work fine:</p>

<pre><code>struct A
{
    constexpr A() = default;

    int x;
};
</code></pre>

<p>however:</p>

<pre><code>Error: defaulted definition of default constructor is not constexpr
</code></pre>

<p>Have you got any clue what is actually going on?</p>