Significance of trivial destruction : <p>In C++17, the new <code>std::optional</code> mandates that it be trivially destructible if <code>T</code> is trivially destructible in [optional.object.dtor]:</p>

<blockquote>
  <p><code>~optional();</code><br>
  1 <em>Effects</em>: If <code>is_trivially_destructible_v&lt;T&gt; != true</code> and <code>*this</code> contains a value, calls <code>val-&gt;T::~T()</code>.<br>
  2 <em>Remarks</em>: If <code>is_trivially_destructible_v&lt;T&gt; == true</code> then this destructor shall be a trivial destructor.</p>
</blockquote>

<p>So this potential implementation fragment would be non-conforming to the standard:</p>

<pre><code>template &lt;class T&gt;
struct wrong_optional {
    union { T value; };
    bool on;

    ~wrong_optional() { if (on) { value.~T(); } }
};
</code></pre>

<p>My question is: what is the advantage of this mandate? Presumably, for trivially destructible types, the compiler can figure out that <code>value.~T()</code> is a no-op and emit no code for <code>wrong_optional&lt;T&gt;::~wrong_optional()</code>. </p>
