What is the difference between the two styles of documentation comments in Rust? (/// vs //!)
<p>The <a href="https://doc.rust-lang.org/book/comments.html" rel="nofollow noreferrer">Rust language doc</a> says the following about documentation comments (emphasis mine):</p>

<blockquote>
  <p>Doc comments use <code>///</code> instead of <code>//</code> [...] There is another style of doc comment, <code>//!</code>, to comment containing items (e.g. crates, modules or <strong>functions</strong>), instead of the items following it.</p>
</blockquote>

<p>And just to confuse things, the document provides an example using the <code>///</code> format to document a <strong>function</strong> (visible via the link, but omitted in the ellipsis, above).</p>

<p>I've seen the two styles used pretty much synonymously before--is there a difference between them in Rust? My searches here and on the interwebs turned up nothing. </p>