text: //===----------------------------------------------------------------------===//
  //
  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  // See https://llvm.org/LICENSE.txt for license information.
  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  //
  //===----------------------------------------------------------------------===//
  
  // UNSUPPORTED: c++03, c++11, c++14, c++17
  // UNSUPPORTED: libcpp-no-concepts
  
  // constexpr counted_iterator() requires default_initializable<I> = default;
  // constexpr counted_iterator(I x, iter_difference_t<I> n);
  // template<class I2>
  //   requires convertible_to<const I2&, I>
  //     constexpr counted_iterator(const counted_iterator<I2>& x);
  
  #include <iterator>
  
  #include "test_macros.h"
  #include "test_iterators.h"
  
  struct InputOrOutputArchetype {
    using difference_type = int;
  
    int *ptr;
  
    constexpr int operator*() { return *ptr; }
    constexpr void operator++(int) { ++ptr; }
    constexpr InputOrOutputArchetype& operator++() { ++ptr; return *this; }
  };
  
  constexpr bool test() {
    int buffer[8] = {1, 2, 3, 4, 5, 6, 7, 8};
  
    {
      std::counted_iterator iter(cpp20_input_iterator<int*>{buffer}, 8);
      assert(iter.base().base() == buffer);
      assert(iter.count() == 8);
    }
  
    {
      std::counted_iterator iter(forward_iterator<int*>{buffer}, 8);
      assert(iter.base() == forward_iterator<int*>{buffer});
      assert(iter.count() == 8);
    }
  
    {
      std::counted_iterator iter(contiguous_iterator<int*>{buffer}, 8);
      assert(iter.base() == contiguous_iterator<int*>{buffer});
      assert(iter.count() == 8);
    }
  
    {
      std::counted_iterator iter(InputOrOutputArchetype{buffer}, 8);
      assert(iter.base().ptr == buffer);
      assert(iter.count() == 8);
    }
  
    {
      const std::counted_iterator iter(cpp20_input_iterator<int*>{buffer}, 8);
      assert(iter.base().base() == buffer);
      assert(iter.count() == 8);
    }
  
    {
      const std::counted_iterator iter(forward_iterator<int*>{buffer}, 7);
      assert(iter.base() == forward_iterator<int*>{buffer});
      assert(iter.count() == 7);
    }
  
    {
      const std::counted_iterator iter(contiguous_iterator<int*>{buffer}, 6);
      assert(iter.base() == contiguous_iterator<int*>{buffer});
      assert(iter.count() == 6);
    }
  
    {
      const std::counted_iterator iter(InputOrOutputArchetype{buffer}, 8);
      assert(iter.base().ptr == buffer);
      assert(iter.count() == 8);
    }
  
    return true;
  }
  
  int main(int, char**) {
    test();
    static_assert(test());
  
    return 0;
  }
  