c++ - Why does std::transform and similar cast the 'for' loop increment to (void)?

Question

What is the purpose of (void) ++__result in the code below?

Implementation for std::transform:

// std::transform
template <class _InputIterator, class _OutputIterator, class _UnaryOperation>
inline _LIBCPP_INLINE_VISIBILITY
_OutputIterator
transform(_InputIterator __first, _InputIterator __last, _OutputIterator __result, _UnaryOperation __op)
{
    for (; __first != __last; ++__first, (void) ++__result)
        *__result = __op(*__first);
    return __result;
}

Answer 1

It is possible to overload operator,. Casting either operand to void prevents any overloaded operator from being called, since overloaded operators cannot take void parameters.