title: return a value without return type declaration in template, is this a typo?
body: <p>I am watching the talk <a href="https://www.youtube.com/watch?v=Am2is2QCvxY">Modern Template Metaprogramming</a> by Walter E. Brown. At 54:40 a code is given as below</p>
  
  <pre><code>template&lt;class T, T v&gt;
  struct integral_constant{
    static constexpr T value = v;
     constexpr  operator T() const noexcept { return value; } // what does this mean?
     constexpr T operator T() const noexcept { return value; }
  };
  </code></pre>
  
  <p>My question is what does this line mean
  <code>constexpr  operator T() const noexcept { return value; }</code>, why there is no return type but it is still returning <code>value</code>? Is this a typo?</p>