Rationale (November, 2016):

The type of the function is needed to know how to call it, and the exception specification is part of the function type.

Consider:

  #include <type_traits>

  template<class T>
  T foo(T) noexcept(std::is_nothrow_move_constructible<T>::value);

  int main()
  {
   sizeof(foo(0));
  }

An exception specification is considered to be needed when:

• in an expression, the function is selected by overload resolution (12.2 [over.match], 12.3 [over.over]);
• ...

Is it intended that the exception specification is needed for the example? The function call is never evaluated and the exception specification is not queried.