title: C++20 template lambda: how to specify template argument?
body: <p>Let's say I have a C++20 template lambda:</p>
  <pre class="lang-cpp prettyprint-override"><code>auto foo = []&lt;bool arg&gt;() {
      if constexpr(arg)
          ...
      else
          ...
  };
  </code></pre>
  <p>But how do I call it? I can't seem to find a description of the syntax. I tried the usual <code>foo&lt;true&gt;();</code> and <code>template foo&lt;true&gt;();</code>, neither of which gcc seems to like.</p>