title: Ruby syntax error unexpected tLABEL
body: <p>I have the following configuration for <a href="https://github.com/rails/rails/pull/31134" rel="nofollow noreferrer">using redis as a rails cache</a>, adapted closely from the rails doc:</p>
  
  <pre><code>Rails.application.configure do
    ...
    config.cache_store = :redis_cache_store, url: "redis://example.com:6379/0"
    ...
  end
  </code></pre>
  
  <p>Using rails 5.2.0.beta2 and ruby 2.3.1p112, my IDE is telling me the following things about the <code>config.cache_store =</code> line:</p>
  
  <ul>
  <li>unused literal ignored</li>
  <li>syntax error, unexpected tLABEL</li>
  </ul>
  
  <p>If I enclose the hash in <code>{}</code>, the errors go away, i.e.:</p>
  
  <pre><code>config.cache_store = :redis_cache_store, { url: "redis://example.com:6379/0" }
  </code></pre>
  
  <p>Is the documentation in error, or is it a ruby version thing (e.g. maybe the doc is assuming ruby >= 2.4)?</p>
  
  <p>In any case, I don't understand what the assignment is actually doing - how can two things be assigned to one?</p>