libstdc++-v3/testsuite/25_algorithms/for_each/constexpr.cc

// Copyright (C) 2019-2021 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING3.  If not see
// <http://www.gnu.org/licenses/>.

// { dg-options "-std=gnu++2a" }
// { dg-do compile { target c++2a } }

#include <algorithm>
#include <array>

constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};

constexpr bool
test()
{
  int tot = 0;
  auto sum = [&total = tot](int i){ total += i; };
  auto sum2 = std::for_each(ca0.begin(), ca0.end(), sum);

  return tot == 66;
}

static_assert(test());

constexpr bool
test_n()
{
  int tot = 0;
  auto sum = [&total = tot](int i){ total += i; };
  auto sum2 = std::for_each_n(ca0.begin(), std::size(ca0)-1, sum);

  return tot == 55;
}

static_assert(test_n());