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
  //
  //===----------------------------------------------------------------------===//
  
  // <algorithm>
  
  // template<BidirectionalIterator InIter, OutputIterator<auto, InIter::reference> OutIter>
  //   constexpr OutIter          // constexpr after C++17
  //   reverse_copy(InIter first, InIter last, OutIter result);
  
  #include <algorithm>
  #include <cassert>
  
  #include "test_macros.h"
  #include "test_iterators.h"
  
  #if TEST_STD_VER > 17
  TEST_CONSTEXPR bool test_constexpr() {
      int ia[] = {1, 3, 5, 2, 5, 6};
      int ib[std::size(ia)] = {0};
  
      auto it = std::reverse_copy(std::begin(ia), std::end(ia), std::begin(ib));
  
      return std::distance(std::begin(ib), it) == static_cast<int>(std::size(ia))
          && std::equal   (std::begin(ia), std::end(ia), std::rbegin(ib))
             ;
      }
  #endif
  
  template <class InIter, class OutIter>
  void
  test()
  {
      const int ia[] = {0};
      const unsigned sa = sizeof(ia)/sizeof(ia[0]);
      int ja[sa] = {-1};
      OutIter r = std::reverse_copy(InIter(ia), InIter(ia), OutIter(ja));
      assert(base(r) == ja);
      assert(ja[0] == -1);
      r = std::reverse_copy(InIter(ia), InIter(ia+sa), OutIter(ja));
      assert(ja[0] == 0);
  
      const int ib[] = {0, 1};
      const unsigned sb = sizeof(ib)/sizeof(ib[0]);
      int jb[sb] = {-1};
      r = std::reverse_copy(InIter(ib), InIter(ib+sb), OutIter(jb));
      assert(base(r) == jb+sb);
      assert(jb[0] == 1);
      assert(jb[1] == 0);
  
      const int ic[] = {0, 1, 2};
      const unsigned sc = sizeof(ic)/sizeof(ic[0]);
      int jc[sc] = {-1};
      r = std::reverse_copy(InIter(ic), InIter(ic+sc), OutIter(jc));
      assert(base(r) == jc+sc);
      assert(jc[0] == 2);
      assert(jc[1] == 1);
      assert(jc[2] == 0);
  
      int id[] = {0, 1, 2, 3};
      const unsigned sd = sizeof(id)/sizeof(id[0]);
      int jd[sd] = {-1};
      r = std::reverse_copy(InIter(id), InIter(id+sd), OutIter(jd));
      assert(base(r) == jd+sd);
      assert(jd[0] == 3);
      assert(jd[1] == 2);
      assert(jd[2] == 1);
      assert(jd[3] == 0);
  }
  
  int main(int, char**)
  {
      test<bidirectional_iterator<const int*>, output_iterator<int*> >();
      test<bidirectional_iterator<const int*>, forward_iterator<int*> >();
      test<bidirectional_iterator<const int*>, bidirectional_iterator<int*> >();
      test<bidirectional_iterator<const int*>, random_access_iterator<int*> >();
      test<bidirectional_iterator<const int*>, int*>();
  
      test<random_access_iterator<const int*>, output_iterator<int*> >();
      test<random_access_iterator<const int*>, forward_iterator<int*> >();
      test<random_access_iterator<const int*>, bidirectional_iterator<int*> >();
      test<random_access_iterator<const int*>, random_access_iterator<int*> >();
      test<random_access_iterator<const int*>, int*>();
  
      test<const int*, output_iterator<int*> >();
      test<const int*, forward_iterator<int*> >();
      test<const int*, bidirectional_iterator<int*> >();
      test<const int*, random_access_iterator<int*> >();
      test<const int*, int*>();
  
  #if TEST_STD_VER > 17
      static_assert(test_constexpr());
  #endif
  
    return 0;
  }
  