<p dir="auto">Using Symfony 2.8.2 or 3.0.2.<br>
You can reproduce the problem with this simple statement:</p>
<div class="highlight highlight-text-html-php notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="$builder-&gt;add('participation', ChoiceType::class, array(
     'choices' =&gt; [ 'yes' =&gt; true, 'no' =&gt; false ],
    'placeholder' =&gt; 'Select a value',
    'empty_data' =&gt; null,
    'choices_as_values' =&gt; true,
));"><pre class="notranslate"><span class="pl-s1"><span class="pl-c1">$</span>builder</span>-&gt;<span class="pl-en">add</span>(<span class="pl-s">'participation'</span>, <span class="pl-v">ChoiceType</span>::class, <span class="pl-en">array</span>(
     <span class="pl-s">'choices'</span> =&gt; [ <span class="pl-s">'yes'</span> =&gt; <span class="pl-c1">true</span>, <span class="pl-s">'no'</span> =&gt; <span class="pl-c1">false</span> ],
    <span class="pl-s">'placeholder'</span> =&gt; <span class="pl-s">'Select a value'</span>,
    <span class="pl-s">'empty_data'</span> =&gt; <span class="pl-c1">null</span>,
    <span class="pl-s">'choices_as_values'</span> =&gt; <span class="pl-c1">true</span>,
));</pre></div>
<p dir="auto">Expected result:</p>
<div class="highlight highlight-text-html-basic notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="&lt;select name=&quot;filter[participation]&quot; id=&quot;filter_participation&quot;&gt;
    &lt;option value=&quot;&quot;&gt;Select a value&lt;/option&gt;
    &lt;option value=&quot;1&quot;&gt;Yes&lt;/option&gt;
    &lt;option selected=&quot;selected&quot; value=&quot;0&quot;&gt;No&lt;/option&gt;
&lt;/select&gt;"><pre class="notranslate"><span class="pl-kos">&lt;</span><span class="pl-ent">select</span> <span class="pl-c1">name</span>="<span class="pl-s">filter[participation]</span>" <span class="pl-c1">id</span>="<span class="pl-s">filter_participation</span>"<span class="pl-kos">&gt;</span>
    <span class="pl-kos">&lt;</span><span class="pl-ent">option</span> <span class="pl-c1">value</span>=""<span class="pl-kos">&gt;</span>Select a value<span class="pl-kos">&lt;/</span><span class="pl-ent">option</span><span class="pl-kos">&gt;</span>
    <span class="pl-kos">&lt;</span><span class="pl-ent">option</span> <span class="pl-c1">value</span>="<span class="pl-s">1</span>"<span class="pl-kos">&gt;</span>Yes<span class="pl-kos">&lt;/</span><span class="pl-ent">option</span><span class="pl-kos">&gt;</span>
    <span class="pl-kos">&lt;</span><span class="pl-ent">option</span> <span class="pl-c1">selected</span>="<span class="pl-s">selected</span>" <span class="pl-c1">value</span>="<span class="pl-s">0</span>"<span class="pl-kos">&gt;</span>No<span class="pl-kos">&lt;/</span><span class="pl-ent">option</span><span class="pl-kos">&gt;</span>
<span class="pl-kos">&lt;/</span><span class="pl-ent">select</span><span class="pl-kos">&gt;</span></pre></div>
<p dir="auto">Actual result:</p>
<div class="highlight highlight-text-html-basic notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="&lt;select name=&quot;filter[participation]&quot; id=&quot;filter_participation&quot;&gt;
    &lt;option value=&quot;1&quot;&gt;Yes&lt;/option&gt;
    &lt;option selected=&quot;selected&quot; value=&quot;&quot;&gt;No&lt;/option&gt;
&lt;/select&gt;"><pre class="notranslate"><span class="pl-kos">&lt;</span><span class="pl-ent">select</span> <span class="pl-c1">name</span>="<span class="pl-s">filter[participation]</span>" <span class="pl-c1">id</span>="<span class="pl-s">filter_participation</span>"<span class="pl-kos">&gt;</span>
    <span class="pl-kos">&lt;</span><span class="pl-ent">option</span> <span class="pl-c1">value</span>="<span class="pl-s">1</span>"<span class="pl-kos">&gt;</span>Yes<span class="pl-kos">&lt;/</span><span class="pl-ent">option</span><span class="pl-kos">&gt;</span>
    <span class="pl-kos">&lt;</span><span class="pl-ent">option</span> <span class="pl-c1">selected</span>="<span class="pl-s">selected</span>" <span class="pl-c1">value</span>=""<span class="pl-kos">&gt;</span>No<span class="pl-kos">&lt;/</span><span class="pl-ent">option</span><span class="pl-kos">&gt;</span>
<span class="pl-kos">&lt;/</span><span class="pl-ent">select</span><span class="pl-kos">&gt;</span></pre></div>
<p dir="auto">Dump of choiceList:</p>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://cloud.githubusercontent.com/assets/652505/12809461/ab8548c8-cb1f-11e5-974b-d38b5dd6c519.png"><img src="https://cloud.githubusercontent.com/assets/652505/12809461/ab8548c8-cb1f-11e5-974b-d38b5dd6c519.png" alt="boolean_choice_dump" style="max-width: 100%;"></a></p>
<p dir="auto">As you can see, the placeholder is not rendered. If I add a new empty value in 'choices', I got an empty value in the view plus the placeholder value.</p>
<p dir="auto">After upgrading from 2.7.7 to 2.7.8 I noticed that some choice fields didn't display the empty value.</p>
<p dir="auto">Example code:</p>
<div class="highlight highlight-text-html-php notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="-&gt;add('buyback', 'choice', [
    'choices' =&gt; [
        'Yes'  =&gt; true,
        'No'   =&gt; false,
    ],
    'choices_as_values' =&gt; true,
    'required'          =&gt; false,
]);"><pre class="notranslate">-&gt;add(<span class="pl-s">'buyback'</span>, <span class="pl-s">'choice'</span>, [
    <span class="pl-s">'choices'</span> =&gt; [
        <span class="pl-s">'Yes'</span>  =&gt; <span class="pl-c1">true</span>,
        <span class="pl-s">'No'</span>   =&gt; <span class="pl-c1">false</span>,
    ],
    <span class="pl-s">'choices_as_values'</span> =&gt; <span class="pl-c1">true</span>,
    <span class="pl-s">'required'</span>          =&gt; <span class="pl-c1">false</span>,
]);</pre></div>
<p dir="auto">Before:<br>
<a target="_blank" rel="noopener noreferrer nofollow" href="https://cloud.githubusercontent.com/assets/407855/12170811/144496ea-b54d-11e5-9a28-a44c9f48ddd5.png"><img src="https://cloud.githubusercontent.com/assets/407855/12170811/144496ea-b54d-11e5-9a28-a44c9f48ddd5.png" alt="image" style="max-width: 100%;"></a><br>
After:<br>
<a target="_blank" rel="noopener noreferrer nofollow" href="https://cloud.githubusercontent.com/assets/407855/12170840/3e399e5a-b54d-11e5-9032-4e0d49fe2a37.png"><img src="https://cloud.githubusercontent.com/assets/407855/12170840/3e399e5a-b54d-11e5-9032-4e0d49fe2a37.png" alt="image" style="max-width: 100%;"></a></p>
<p dir="auto">So far I've found out that the <code class="notranslate">false</code> value is converted to empty string in this line <a class="commit-link" href="https://github.com/symfony/symfony/compare/v2.7.7...v2.7.8#diff-780e59a429c485d2d3b8a37fdf62ac59R79"><tt>v2.7.7...v2.7.8</tt>#diff-780e59a429c485d2d3b8a37fdf62ac59R79</a>.</p>
<p dir="auto">I think that the <code class="notranslate">false</code> value is displayed instead of empty value because of that.</p>
<p dir="auto">This bug was introduced in <a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="119163490" data-permission-text="Title is private" data-url="https://github.com/symfony/symfony/issues/16705" data-hovercard-type="pull_request" data-hovercard-url="/symfony/symfony/pull/16705/hovercard" href="https://github.com/symfony/symfony/pull/16705">#16705</a>.</p>