title: Which "C# Experimental language feature" is this?
body: <p>In the example below, Resharper shows "C# Experimental language feature" tooltip on the first curly bracket. I've checked the new features of C# 6.0 but didn't come across a similar one. What is the referred experimental feature?</p>
  
  <pre><code> class Class1
   {
       { // &lt;= C# Experimental language feature
       }
   }
  </code></pre>
  
  <p>Note: It is an error for .Net Framework 4.5 compiler. </p>
  
  <blockquote>
    <p>"Invalid token '{' in class, struct, or interface member declaration"</p>
  </blockquote>