ClangFormat: Maybe leads to an endless loop

 template<typename _Container>
    inline back_insert_iterator<_Container>
    back_inserter(_Container& __x)
    { return back_insert_iterator<_Container>(__x); }

  /**
   *  @brief  Turns assignment into insertion.
   *
   *  These are output iterators, constructed from a container-of-T.
   *  Assigning a T to the iterator prepends it to the container using
   *  push_front.
   *
   *  Tip:  Using the front_inserter function to create these iterators can
   *  save typing.
  */
  template<typename _Container>
    class front_insert_iterator
    : public iterator<output_iterator_tag, void, void, void, void>
    {
    protected:
      _Container* container;

    public:
      /// A nested typedef for the type of whatever container you used.
      typedef _Container          container_type;

      /// The only way to create this %iterator is with a container.
      explicit front_insert_iterator(_Container& __x)
      : container(std::__addressof(__x)) { }

      /**
       *  @param  __value  An instance of whatever type
       *                 container_type::const_reference is; presumably a
       *                 reference-to-const T for container<T>.
       *  @return  This %iterator, for chained operations.
       *
       *  This kind of %iterator doesn't really have a @a position in the
       *  container (you can think of the position as being permanently at
       *  the front, if you like).  Assigning a value to the %iterator will
       *  always prepend the value to the front of the container.
      */
#if __cplusplus < 201103L
      front_insert_iterator&
      operator=(typename _Container::const_reference __value)
      {
	container->push_front(__value);
	return *this;
      }
#else
      front_insert_iterator&
      operator=(const typename _Container::value_type& __value)
      {
	container->push_front(__value);
	return *this;
      }

      front_insert_iterator&
      operator=(typename _Container::value_type&& __value)
      {
	container->push_front(std::move(__value));
	return *this;
      }
#endif

      /// Simply returns *this.
      front_insert_iterator&
      operator*()
      { return *this; }

      /// Simply returns *this.  (This %iterator does not @a move.)
      front_insert_iterator&
      operator++()
      { return *this; }

      /// Simply returns *this.  (This %iterator does not @a move.)
      front_insert_iterator
      operator++(int)
      { return *this; }
    };