libstdc++-v3/testsuite/24_iterators/front_insert_iterator/constexpr.cc

   1 // Copyright (C) 2020-2023 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   7 // any later version.
   8
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13
  14 // You should have received a copy of the GNU General Public License along
  15 // with this library; see the file COPYING3.  If not see
  16 // <http://www.gnu.org/licenses/>.
  17
  18 // { dg-options "-std=gnu++2a" }
  19 // { dg-do compile { target c++2a } }
  20
  21 #include <iterator>
  22
  23 struct container
  24 {
  25   using value_type = int;
  26
  27   constexpr int* begin() { return next; }
  28   constexpr int* end() { return std::end(data); }
  29
  30   constexpr void push_front(int val)
  31   {
  32     if (next == std::begin(data))
  33       throw val;
  34     *--next = val;
  35   }
  36
  37   int data[3];
  38   int* next = std::end(data);
  39 };
  40
  41 constexpr bool
  42 test01()
  43 {
  44   container c;
  45   std::front_insert_iterator<container> iter = std::front_inserter(c);
  46   *iter++ = 1;
  47   int i = 2;
  48   *iter = i;
  49   *++iter = 3;
  50   return c.data[0] == 3 && c.data[1] == 2 && c.data[2] == 1;
  51 }
  52
  53 static_assert( test01() );