 which makes this conversion mechanism
pretty much useless for constexpr code. Besides, <code>outcome</code> has a converting
constructor overload for <code>result</code> inputs which is constexpr capable.</p>

<p>Note that if you do enable <code>outcome</code> inputs, a <code>result</code> will match an input
<code>outcome</code>, but silently dropping any exception state. This is probably undesirable.</p>

<p>Examples of how to implement your own <code>convert::value_or_error&lt;T, U&gt;</code> converter
