 the following program.</p>
<pre><code>parameters {
  real unb_p;
  real&lt;lower=0&gt; pos_p;
}
model {
  1 ~ poisson(unb_p);
  1 ~ poisson(pos_p);
}</code></pre>
<p>The parameter of <code>poisson</code> should be strictly positive, but <code>unb_p</code> is not constrained to be positive.</p>
<p>Pedantic mode produces the following warning.</p>
<pre><code>Warning at &#39;ex-dist-args.stan&#39;, line 6, column 14 to column 19:
  A poisson distribution is given parameter unb_p as a rate parameter
  (argumen