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<InputIterator InIter, OutputIterator<auto, InIter::reference> OutIter,
  //          Predicate<auto, InIter::value_type> Pred>
  //   requires CopyConstructible<Pred>
  //   constexpr OutIter         // constexpr after C++17
  //   remove_copy_if(InIter first, InIter last, OutIter result, Pred pred);
  
  #include <algorithm>
  #include <functional>
  #include <cassert>
  
  #include "test_macros.h"
  #include "test_iterators.h"
  
  TEST_CONSTEXPR bool equalToTwo(int v) { return v == 2; }
  
  #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::remove_copy_if(std::begin(ia), std::end(ia), std::begin(ib), equalToTwo);
  
      return std::distance(std::begin(ib), it) == static_cast<int>(std::size(ia) - 1)   // we removed one element
          && std::none_of(std::begin(ib), it, equalToTwo)
          && std::all_of (it, std::end(ib), [](int a) {return a == 0;})
             ;
      }
  #endif
  
  template <class InIter, class OutIter>
  void
  test()
  {
      int ia[] = {0, 1, 2, 3, 4, 2, 3, 4, 2};
      const unsigned sa = sizeof(ia)/sizeof(ia[0]);
      int ib[sa];
      OutIter r = std::remove_copy_if(InIter(ia), InIter(ia+sa),
                                      OutIter(ib), equalToTwo);
      assert(base(r) == ib + sa-3);
      assert(ib[0] == 0);
      assert(ib[1] == 1);
      assert(ib[2] == 3);
      assert(ib[3] == 4);
      assert(ib[4] == 3);
      assert(ib[5] == 4);
  }
  
  int main(int, char**)
  {
      test<cpp17_input_iterator<const int*>, cpp17_output_iterator<int*> >();
      test<cpp17_input_iterator<const int*>, forward_iterator<int*> >();
      test<cpp17_input_iterator<const int*>, bidirectional_iterator<int*> >();
      test<cpp17_input_iterator<const int*>, random_access_iterator<int*> >();
      test<cpp17_input_iterator<const int*>, int*>();
  
      test<forward_iterator<const int*>, cpp17_output_iterator<int*> >();
      test<forward_iterator<const int*>, forward_iterator<int*> >();
      test<forward_iterator<const int*>, bidirectional_iterator<int*> >();
      test<forward_iterator<const int*>, random_access_iterator<int*> >();
      test<forward_iterator<const int*>, int*>();
  
      test<bidirectional_iterator<const int*>, cpp17_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*>, cpp17_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*, cpp17_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;
  }
  