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<class Iter, IntegralLike Size, Callable Generator>
  //   requires OutputIterator<Iter, Generator::result_type>
  //         && CopyConstructible<Generator>
  //   constexpr void      // constexpr after c++17
  //   generate_n(Iter first, Size n, Generator gen);
  
  #include "test_macros.h"
  
  #ifdef TEST_COMPILER_C1XX
  #pragma warning(disable: 4244) // conversion from 'const double' to 'int', possible loss of data
  #endif
  
  #include <algorithm>
  #include <cassert>
  
  #include "test_iterators.h"
  #include "user_defined_integral.h"
  
  struct gen_test
  {
      TEST_CONSTEXPR int operator()() const {return 2;}
  };
  
  
  #if TEST_STD_VER > 17
  TEST_CONSTEXPR bool test_constexpr() {
      const size_t N = 5;
      int ib[] = {0, 0, 0, 0, 0, 0}; // one bigger than N
  
      auto it = std::generate_n(std::begin(ib), N, gen_test());
  
      return it == (std::begin(ib) + N)
          && std::all_of(std::begin(ib), it, [](int x) { return x == 2; })
          && *it == 0 // don't overwrite the last value in the output array
          ;
      }
  #endif
  
  
  template <class Iter, class Size>
  void
  test2()
  {
      const unsigned n = 4;
      int ia[n] = {0};
      assert(std::generate_n(Iter(ia), Size(n), gen_test()) == Iter(ia+n));
      assert(ia[0] == 2);
      assert(ia[1] == 2);
      assert(ia[2] == 2);
      assert(ia[3] == 2);
  }
  
  template <class Iter>
  void
  test()
  {
      test2<Iter, int>();
      test2<Iter, unsigned int>();
      test2<Iter, long>();
      test2<Iter, unsigned long>();
      test2<Iter, UserDefinedIntegral<unsigned> >();
      test2<Iter, float>();
      test2<Iter, double>();  // this is PR#35498
      test2<Iter, long double>();
  }
  
  int main(int, char**)
  {
      test<forward_iterator<int*> >();
      test<bidirectional_iterator<int*> >();
      test<random_access_iterator<int*> >();
      test<int*>();
  
  #if TEST_STD_VER > 17
      static_assert(test_constexpr());
  #endif
  
    return 0;
  }
  