title: Negating a concept (C++20)
body: <p>Playing around, I noticed that the following code compiles on MSVC 19.27</p>
  <pre><code>template &lt;typename T&gt;
  concept defined = true;
  
  template &lt;!defined T&gt;             // &lt;=== !!!!!!!!
  inline auto constexpr Get()
  {
      return 5;  
  }
  </code></pre>
  <p>What's going on? Is it such a bad idea to allow this syntax?</p>