he future will prompt a compilation failure, rather than runtime panic.
Second, it makes cost explicit. In general, the only safe way to have a
non-exhaustive match would be to panic the thread if nothing is matched, though
it could fall through if the type of the <code>match</code> expression is <code>()</code>. This sort
of hidden cost and special casing is against the language&#39;s philosophy. It&#39;s
easy to ignore all unspecified cases by using the <code>_</code> wildcard:</p>

<span class='rusttest'