1// Copyright Louis Dionne 2013-2022
2// Distributed under the Boost Software License, Version 1.0.
3// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
4
5#include <boost/hana/assert.hpp>
6#include <boost/hana/equal.hpp>
7#include <boost/hana/type.hpp>
8namespace hana = boost::hana;
9
10
11using Function = void();
12void function() { }
13
14int main() {
15 {
16 struct T { };
17 T t;
18
19 BOOST_HANA_CONSTANT_CHECK(hana::equal(
20 hana::decltype_(T{}),
21 hana::type_c<T>
22 ));
23
24 BOOST_HANA_CONSTANT_CHECK(hana::equal(
25 hana::decltype_(t),
26 hana::type_c<T>
27 ));
28 }
29
30 // [cv-qualified] reference types
31 {
32 struct T { };
33 T t;
34
35 BOOST_HANA_CONSTANT_CHECK(hana::equal(
36 hana::decltype_(static_cast<T&>(t)),
37 hana::type_c<T>
38 ));
39
40 BOOST_HANA_CONSTANT_CHECK(hana::equal(
41 hana::decltype_(static_cast<T const&>(t)),
42 hana::type_c<T const>
43 ));
44
45 BOOST_HANA_CONSTANT_CHECK(hana::equal(
46 hana::decltype_(static_cast<T volatile&>(t)),
47 hana::type_c<T volatile>
48 ));
49
50 BOOST_HANA_CONSTANT_CHECK(hana::equal(
51 hana::decltype_(static_cast<T const volatile&>(t)),
52 hana::type_c<T const volatile>
53 ));
54 }
55
56 // [cv-qualified] rvalue reference types
57 {
58 struct T { };
59 T t;
60
61 BOOST_HANA_CONSTANT_CHECK(hana::equal(
62 hana::decltype_(static_cast<T&&>(t)),
63 hana::type_c<T>
64 ));
65
66 BOOST_HANA_CONSTANT_CHECK(hana::equal(
67 hana::decltype_(static_cast<T const &&>(t)),
68 hana::type_c<T const>
69 ));
70
71 BOOST_HANA_CONSTANT_CHECK(hana::equal(
72 hana::decltype_(static_cast<T volatile&&>(t)),
73 hana::type_c<T volatile>
74 ));
75
76 BOOST_HANA_CONSTANT_CHECK(hana::equal(
77 hana::decltype_(static_cast<T const volatile&&>(t)),
78 hana::type_c<T const volatile>
79 ));
80 }
81
82 // decltype_(type_c<T>) is the identity function
83 {
84 struct T;
85 auto const type_const = hana::type_c<T>;
86 auto const& type_const_ref = hana::type_c<T>;
87 auto& type_ref = hana::type_c<T>;
88 auto&& type_ref_ref = static_cast<decltype(type_ref)&&>(type_ref);
89
90 BOOST_HANA_CONSTANT_CHECK(hana::equal(
91 hana::decltype_(hana::type_c<T>),
92 hana::type_c<T>
93 ));
94
95 BOOST_HANA_CONSTANT_CHECK(hana::equal(
96 hana::decltype_(type_const),
97 hana::type_c<T>
98 ));
99
100 BOOST_HANA_CONSTANT_CHECK(hana::equal(
101 hana::decltype_(type_const_ref),
102 hana::type_c<T>
103 ));
104
105 BOOST_HANA_CONSTANT_CHECK(hana::equal(
106 hana::decltype_(type_ref),
107 hana::type_c<T>
108 ));
109
110 BOOST_HANA_CONSTANT_CHECK(hana::equal(
111 hana::decltype_(type_ref_ref),
112 hana::type_c<T>
113 ));
114 }
115
116 // make sure we don't read from non-constexpr variables
117 {
118 struct T;
119 auto t = hana::type_c<T>;
120 auto x = 1;
121 constexpr auto r1 = hana::decltype_(t); (void)r1;
122 constexpr auto r2 = hana::decltype_(x); (void)r2;
123 }
124
125 // decltype_ with builtin arrays, function pointers and other weirdos
126 {
127 struct T { };
128 using A = T[3];
129 A a;
130 A& a_ref = a;
131 A const& a_const_ref = a;
132
133 BOOST_HANA_CONSTANT_CHECK(hana::equal(
134 hana::decltype_(a),
135 hana::type_c<A>
136 ));
137
138 BOOST_HANA_CONSTANT_CHECK(hana::equal(
139 hana::decltype_(a_ref),
140 hana::type_c<A>
141 ));
142
143 BOOST_HANA_CONSTANT_CHECK(hana::equal(
144 hana::decltype_(a_const_ref),
145 hana::type_c<A const>
146 ));
147 }
148 {
149 using Fptr = int(*)();
150 Fptr f;
151 Fptr& f_ref = f;
152 Fptr const& f_const_ref = f;
153
154 BOOST_HANA_CONSTANT_CHECK(hana::equal(
155 hana::decltype_(f),
156 hana::type_c<Fptr>
157 ));
158
159 BOOST_HANA_CONSTANT_CHECK(hana::equal(
160 hana::decltype_(f_ref),
161 hana::type_c<Fptr>
162 ));
163
164 BOOST_HANA_CONSTANT_CHECK(hana::equal(
165 hana::decltype_(f_const_ref),
166 hana::type_c<Fptr const>
167 ));
168 }
169 {
170 Function& function_ref = function;
171
172 BOOST_HANA_CONSTANT_CHECK(hana::equal(
173 hana::decltype_(function),
174 hana::type_c<Function>
175 ));
176
177 BOOST_HANA_CONSTANT_CHECK(hana::equal(
178 hana::decltype_(function_ref),
179 hana::type_c<Function>
180 ));
181 }
182}
183

source code of boost/libs/hana/test/type/decltype.cpp