title: How to concatenate two Twig variables in a loop
body: <p>I'm trying to create dynamically variable name so the result to be as the one below</p>
  
  <pre><code>{{ form_label(form.user_1) }}
   {{ form_label(form.user_2) }}
   {{ form_label(form.user_3) }}
   {{ form_label(form.user_4) }}
  </code></pre>
  
  <p>Here's what I tried so far </p>
  
  <pre><code>{%  for user in users %}
        {{ form_label(form.user~'_'~loop.index) }}
   {% endfor %}
  </code></pre>
  
  <p>but get </p>
  
  <blockquote>
    <p>Argument 1 passed to
    Symfony\Component\Form\FormRenderer::searchAndRenderBlock() must be an
    instance of Symfony\Component\Form\FormView, string given</p>
  </blockquote>
  
  <p>What I'm doing wrong?</p>