title: Whats the best way to deprecate a field in Protocol Buffer v3, reserved vs deprecated=true?
body: <p>When using Protocol Buffers version 3, from what I can see, there are 2 ways you can deprecate a field:</p>
  
  <p>Either using the deprecate field using tags:</p>
  
  <pre><code>message MyMessage {
      string deprecated_my_field = 1 [deprecated=true];
  }
  </code></pre>
  
  <p>Or creating a reserved field ID:</p>
  
  <pre><code>message MyMessage {
      reserved 1; // Deprecated "my_field"
  }
  </code></pre>
  
  <p>I am leaning towards <code>reserved</code> since then no one will be able to use the field.</p>
  
  <p>Is this a bad idea?</p>