1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9// type_traits
10
11// is_empty
12
13// T is a non-union class type with:
14// no non-static data members,
15// no unnamed bit-fields of non-zero length,
16// no virtual member functions,
17// no virtual base classes,
18// and no base class B for which is_empty_v<B> is false.
19
20
21#include <type_traits>
22#include "test_macros.h"
23
24template <class T>
25void test_is_empty()
26{
27 static_assert( std::is_empty<T>::value, "");
28 static_assert( std::is_empty<const T>::value, "");
29 static_assert( std::is_empty<volatile T>::value, "");
30 static_assert( std::is_empty<const volatile T>::value, "");
31#if TEST_STD_VER > 14
32 static_assert( std::is_empty_v<T>, "");
33 static_assert( std::is_empty_v<const T>, "");
34 static_assert( std::is_empty_v<volatile T>, "");
35 static_assert( std::is_empty_v<const volatile T>, "");
36#endif
37}
38
39template <class T>
40void test_is_not_empty()
41{
42 static_assert(!std::is_empty<T>::value, "");
43 static_assert(!std::is_empty<const T>::value, "");
44 static_assert(!std::is_empty<volatile T>::value, "");
45 static_assert(!std::is_empty<const volatile T>::value, "");
46#if TEST_STD_VER > 14
47 static_assert(!std::is_empty_v<T>, "");
48 static_assert(!std::is_empty_v<const T>, "");
49 static_assert(!std::is_empty_v<volatile T>, "");
50 static_assert(!std::is_empty_v<const volatile T>, "");
51#endif
52}
53
54class Empty {};
55struct NotEmpty { int foo; };
56
57class VirtualFn
58{
59 virtual ~VirtualFn();
60};
61
62union Union {};
63
64struct EmptyBase : public Empty {};
65struct VirtualBase : virtual Empty {};
66struct NotEmptyBase : public NotEmpty {};
67
68struct StaticMember { static int foo; };
69struct NonStaticMember { int foo; };
70
71struct bit_zero
72{
73 int : 0;
74};
75
76struct bit_one
77{
78 int : 1;
79};
80
81int main(int, char**)
82{
83 test_is_not_empty<void>();
84 test_is_not_empty<int&>();
85 test_is_not_empty<int>();
86 test_is_not_empty<double>();
87 test_is_not_empty<int*>();
88 test_is_not_empty<const int*>();
89 test_is_not_empty<char[3]>();
90 test_is_not_empty<char[]>();
91 test_is_not_empty<Union>();
92 test_is_not_empty<NotEmpty>();
93 test_is_not_empty<VirtualFn>();
94 test_is_not_empty<VirtualBase>();
95 test_is_not_empty<NotEmptyBase>();
96 test_is_not_empty<NonStaticMember>();
97// test_is_not_empty<bit_one>();
98
99 test_is_empty<Empty>();
100 test_is_empty<EmptyBase>();
101 test_is_empty<StaticMember>();
102 test_is_empty<bit_zero>();
103
104 return 0;
105}
106

source code of libcxx/test/std/utilities/meta/meta.unary/meta.unary.prop/is_empty.pass.cpp