title: Can I tag a C# function as "this function does not enumerate the IEnumerable parameter"?
body: <p>Multiple enumeration of the same enumerable is something that has been a performance problem for us, so we try to stomp those warnings in the code. But there is a generic extension function that we have for throwing null parameter exceptions that generates a lot of these warnings. Its signature looks like this:</p>
  
  <pre><code>public static void VerifyArgumentIsNotNull&lt;T&gt;(this T value, string valueName) where T : class
  </code></pre>
  
  <p>All it does is check for null and throw a nicely formatted and localized (for whichever human language is in play at the time) exception. </p>
  
  <p>When this function is used on an IEnumerable parameter, it makes the code analysis warn about a possible multiple iteration of the IEnumerable because the analyzer has no idea what that function does. </p>
  
  <p>I would like to put some tag on this function that says, "Yes, this takes the enumerable as an input, but it does not iterate it and therefore should not be counted as a possible iteration by callers." Is there any such tag? I've searched the Internet to no avail.</p>