message: Silence deprecation warning
diff: #pragma once
  -#include <iterator>
  -
  #include "caf/detail/type_traits.hpp"
  +#include <cstddef>
  +#include <iterator>
  +
  namespace caf {
  template <class T>
  @@ -21,8 +22,18 @@ public:
  input_range(const input_range&) = default;
  input_range& operator=(const input_range&) = default;
  - class iterator : public std::iterator<std::input_iterator_tag, T> {
  + class iterator {
  public:
  + using iterator_category = std::input_iterator_tag;
  +
  + using value_type = T;
  +
  + using difference_type = ptrdiff_t;
  +
  + using pointer = T*;
  +
  + using reference = T&;
  +
  iterator(input_range* range) : xs_(range) {
  if (xs_)
  advance();
  