1 // Copyright (C) 2020-2025 Free Software Foundation, Inc.
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)
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.
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/>.
18 // { dg-do run { target c++20 } }
21 #include <testsuite_hooks.h>
26 std::stack
<int> c1
{ {1, 2, 3} }, c2
{ {1, 2, 3, 4} }, c3
{ {1, 2, 4} };
28 VERIFY( std::is_eq(c1
<=> c1
) );
30 VERIFY( std::is_lt(c1
<=> c2
) );
32 VERIFY( std::is_lt(c1
<=> c3
) );
34 VERIFY( std::is_lt(c2
<=> c3
) );
36 static_assert( std::totally_ordered
<std::stack
<int>> );
38 static_assert( std::three_way_comparable
<std::stack
<int>,
39 std::strong_ordering
> );
40 static_assert( ! std::three_way_comparable
<std::stack
<float>,
41 std::strong_ordering
> );
42 static_assert( ! std::three_way_comparable
<std::stack
<float>,
43 std::weak_ordering
> );
44 static_assert( std::three_way_comparable
<std::stack
<float>,
45 std::partial_ordering
> );
49 bool operator==(E
) { return true; }
51 static_assert( ! std::three_way_comparable
<E
> );
52 static_assert( ! std::three_way_comparable
<std::stack
<E
>> );