1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
|
// Copyright Louis Dionne 2013-2017
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
#include <boost/hana/at.hpp>
#include <boost/hana/bool.hpp>
#include <boost/hana/first.hpp>
#include <boost/hana/integral_constant.hpp>
#include <boost/hana/pair.hpp>
#include <boost/hana/second.hpp>
#include <boost/hana/tuple.hpp>
#include <type_traits>
#include <utility>
namespace hana = boost::hana;
// In GitHub issue #331, we noticed that `first` and `second` could sometimes
// return the wrong member in case of nested pairs. This is due to the way we
// inherit from base classes to enable EBO. We also check for `basic_tuple`,
// because both are implemented similarly.
int main() {
{
using Nested = hana::pair<hana::int_<1>, hana::int_<2>>;
using Pair = hana::pair<hana::int_<0>, Nested>;
Pair pair{};
auto a = hana::first(pair);
static_assert(std::is_same<decltype(a), hana::int_<0>>{}, "");
auto b = hana::second(pair);
static_assert(std::is_same<decltype(b), Nested>{}, "");
}
{
using Nested = hana::basic_tuple<hana::int_<1>, hana::int_<2>>;
using Tuple = hana::basic_tuple<hana::int_<0>, Nested>;
Tuple tuple{};
auto a = hana::at_c<0>(tuple);
static_assert(std::is_same<decltype(a), hana::int_<0>>{}, "");
auto b = hana::at_c<1>(tuple);
static_assert(std::is_same<decltype(b), Nested>{}, "");
}
// Original test case submitted by Vittorio Romeo
{
hana::pair<hana::int_<1>, hana::bool_<false>> p{};
auto copy = hana::make_pair(hana::int_c<0>, p);
auto move = hana::make_pair(hana::int_c<0>, std::move(p));
copy = move; // copy assign
copy = std::move(move); // move assign
}
}
|
