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
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
|
// { dg-do run { target c++11 } }
// Copyright (C) 2016-2020 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/>.
// 27.6.2.5.3 basic_ostream manipulator inserters
#include <sstream>
struct X {};
std::wistream& operator>>(std::wistream&, X&) = delete;
struct Y {};
std::wistream& operator>>(std::wistream& is, Y&) {return is;}
std::wistream& operator>>(std::wistream& is, Y&&) {return is;}
struct Z{};
template <class T>
auto f(T&&) -> decltype(void(std::declval<std::wistream&>()
>> std::declval<T&&>()),
std::true_type());
std::false_type f(...);
template <class T>
auto g(T&&) -> decltype(void(std::declval<std::wistream&&>()
>> std::declval<T&&>()),
std::true_type());
std::false_type g(...);
void test01()
{
Y y;
std::wistringstream is;
is >> y;
is >> Y();
std::wistringstream() >> y;
std::wistringstream() >> Y();
static_assert(!std::__is_extractable<std::wistream&, X&>::value, "");
static_assert(!std::__is_extractable<std::wistream&&, X&>::value, "");
static_assert(!std::__is_extractable<std::wistream&, X&&>::value, "");
static_assert(!std::__is_extractable<std::wistream&&, X&&>::value, "");
static_assert(std::__is_extractable<std::wistream&, Y&>::value, "");
static_assert(std::__is_extractable<std::wistream&&, Y&>::value, "");
static_assert(std::__is_extractable<std::wistream&, Y&&>::value, "");
static_assert(std::__is_extractable<std::wistream&&, Y&&>::value, "");
static_assert(!std::__is_extractable<std::wistream&, Z&>::value, "");
static_assert(!std::__is_extractable<std::wistream&&, Z&>::value, "");
static_assert(!std::__is_extractable<std::wistream&, Z&&>::value, "");
static_assert(!std::__is_extractable<std::wistream&&, Z&&>::value, "");
static_assert(std::is_same<decltype(f(std::declval<X&>())),
std::false_type>::value, "");
static_assert(std::is_same<decltype(f(std::declval<X&&>())),
std::false_type>::value, "");
static_assert(std::is_same<decltype(f(std::declval<Y&>())),
std::true_type>::value, "");
static_assert(std::is_same<decltype(f(std::declval<Y&&>())),
std::true_type>::value, "");
static_assert(std::is_same<decltype(f(std::declval<Z&>())),
std::false_type>::value, "");
static_assert(std::is_same<decltype(f(std::declval<Z&&>())),
std::false_type>::value, "");
static_assert(std::is_same<decltype(g(std::declval<X&>())),
std::false_type>::value, "");
static_assert(std::is_same<decltype(g(std::declval<X&&>())),
std::false_type>::value, "");
static_assert(std::is_same<decltype(g(std::declval<Y&>())),
std::true_type>::value, "");
static_assert(std::is_same<decltype(g(std::declval<Y&&>())),
std::true_type>::value, "");
static_assert(std::is_same<decltype(g(std::declval<Z&>())),
std::false_type>::value, "");
static_assert(std::is_same<decltype(g(std::declval<Z&&>())),
std::false_type>::value, "");
}
int main()
{
test01();
}
|