text: //===----------------------------------------------------------------------===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is dual licensed under the MIT and the University of Illinois Open
  // Source Licenses. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  
  // <algorithm>
  
  // template<InputIterator Iter1, InputIterator Iter2, typename Compare>
  //   requires Predicate<Compare, Iter1::value_type, Iter2::value_type>
  //         && Predicate<Compare, Iter2::value_type, Iter1::value_type>
  //   constexpr bool             // constexpr after C++17
  //   includes(Iter1 first1, Iter1 last1, Iter2 first2, Iter2 last2, Compare comp);
  
  #include <algorithm>
  #include <functional>
  #include <cassert>
  
  #include "test_macros.h"
  #include "test_iterators.h"
  
  #if TEST_STD_VER > 17
  TEST_CONSTEXPR bool test_constexpr() {
      int ia[] = {1, 2, 2, 3, 3, 3, 4, 4, 4, 4};
      int ib[] = {2, 4};
      int ic[] = {3, 3, 3, 3};
      
      auto comp = [](int a, int b) {return a < b; };
      return  std::includes(std::begin(ia), std::end(ia), std::begin(ib), std::end(ib), comp)
          && !std::includes(std::begin(ia), std::end(ia), std::begin(ic), std::end(ic), comp)
             ;
      }
  #endif
  
  
  template <class Iter1, class Iter2>
  void
  test()
  {
      int ia[] = {1, 2, 2, 3, 3, 3, 4, 4, 4, 4};
      const unsigned sa = sizeof(ia)/sizeof(ia[0]);
      int ib[] = {2, 4};
      const unsigned sb = sizeof(ib)/sizeof(ib[0]);
      int ic[] = {1, 2};
      const unsigned sc = sizeof(ic)/sizeof(ic[0]); ((void)sc);
      int id[] = {3, 3, 3, 3};
      const unsigned sd = sizeof(id)/sizeof(id[0]); ((void)sd);
  
      assert(std::includes(Iter1(ia), Iter1(ia), Iter2(ib), Iter2(ib), std::less<int>()));
      assert(!std::includes(Iter1(ia), Iter1(ia), Iter2(ib), Iter2(ib+1), std::less<int>()));
      assert(std::includes(Iter1(ia), Iter1(ia+1), Iter2(ib), Iter2(ib), std::less<int>()));
      assert(std::includes(Iter1(ia), Iter1(ia+sa), Iter2(ia), Iter2(ia+sa), std::less<int>()));
  
      assert(std::includes(Iter1(ia), Iter1(ia+sa), Iter2(ib), Iter2(ib+sb), std::less<int>()));
      assert(!std::includes(Iter1(ib), Iter1(ib+sb), Iter2(ia), Iter2(ia+sa), std::less<int>()));
  
      assert(std::includes(Iter1(ia), Iter1(ia+2), Iter2(ic), Iter2(ic+2), std::less<int>()));
      assert(!std::includes(Iter1(ia), Iter1(ia+2), Iter2(ib), Iter2(ib+2), std::less<int>()));
  
      assert(std::includes(Iter1(ia), Iter1(ia+sa), Iter2(id), Iter2(id+1), std::less<int>()));
      assert(std::includes(Iter1(ia), Iter1(ia+sa), Iter2(id), Iter2(id+2), std::less<int>()));
      assert(std::includes(Iter1(ia), Iter1(ia+sa), Iter2(id), Iter2(id+3), std::less<int>()));
      assert(!std::includes(Iter1(ia), Iter1(ia+sa), Iter2(id), Iter2(id+4), std::less<int>()));
  }
  
  int main()
  {
      test<input_iterator<const int*>, input_iterator<const int*> >();
      test<input_iterator<const int*>, forward_iterator<const int*> >();
      test<input_iterator<const int*>, bidirectional_iterator<const int*> >();
      test<input_iterator<const int*>, random_access_iterator<const int*> >();
      test<input_iterator<const int*>, const int*>();
  
      test<forward_iterator<const int*>, input_iterator<const int*> >();
      test<forward_iterator<const int*>, forward_iterator<const int*> >();
      test<forward_iterator<const int*>, bidirectional_iterator<const int*> >();
      test<forward_iterator<const int*>, random_access_iterator<const int*> >();
      test<forward_iterator<const int*>, const int*>();
  
      test<bidirectional_iterator<const int*>, input_iterator<const int*> >();
      test<bidirectional_iterator<const int*>, forward_iterator<const int*> >();
      test<bidirectional_iterator<const int*>, bidirectional_iterator<const int*> >();
      test<bidirectional_iterator<const int*>, random_access_iterator<const int*> >();
      test<bidirectional_iterator<const int*>, const int*>();
  
      test<random_access_iterator<const int*>, input_iterator<const int*> >();
      test<random_access_iterator<const int*>, forward_iterator<const int*> >();
      test<random_access_iterator<const int*>, bidirectional_iterator<const int*> >();
      test<random_access_iterator<const int*>, random_access_iterator<const int*> >();
      test<random_access_iterator<const int*>, const int*>();
  
      test<const int*, input_iterator<const int*> >();
      test<const int*, forward_iterator<const int*> >();
      test<const int*, bidirectional_iterator<const int*> >();
      test<const int*, random_access_iterator<const int*> >();
      test<const int*, const int*>();
  
  #if TEST_STD_VER > 17
     static_assert(test_constexpr());
  #endif
  }
  