1 //===----------------------------------------------------------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 // UNSUPPORTED: c++03, c++11, c++14, c++17
10 
11 // template <class T>
12 //   constexpr bool has_single_bit(T x) noexcept;
13 
14 // Constraints: T is an unsigned integer type
15 
16 #include <bit>
17 #include <cassert>
18 #include <cstdint>
19 #include <type_traits>
20 
21 #include "test_macros.h"
22 
23 struct A {};
24 enum       E1 : unsigned char { rEd };
25 enum class E2 : unsigned char { red };
26 
27 template <class T>
28 constexpr bool test()
29 {
30     ASSERT_SAME_TYPE(decltype(std::has_single_bit(T())), bool);
31     ASSERT_NOEXCEPT(std::has_single_bit(T()));
32     T max = std::numeric_limits<T>::max();
33 
34     assert(!std::has_single_bit(T(0)));
35     assert( std::has_single_bit(T(1)));
36     assert( std::has_single_bit(T(2)));
37     assert(!std::has_single_bit(T(3)));
38     assert( std::has_single_bit(T(4)));
39     assert(!std::has_single_bit(T(5)));
40     assert(!std::has_single_bit(T(6)));
41     assert(!std::has_single_bit(T(7)));
42     assert( std::has_single_bit(T(8)));
43     assert(!std::has_single_bit(T(9)));
44     assert(!std::has_single_bit(T(127)));
45     assert( std::has_single_bit(T(128)));
46     assert(!std::has_single_bit(T(129)));
47     assert(!std::has_single_bit(max));
48 
49 #ifndef _LIBCPP_HAS_NO_INT128
50     if constexpr (std::is_same_v<T, __uint128_t>) {
51         T val = T(1) << 32;
52         assert(!std::has_single_bit(val-1));
53         assert( std::has_single_bit(val));
54         assert(!std::has_single_bit(val+1));
55         val <<= 60;
56         assert(!std::has_single_bit(val-1));
57         assert( std::has_single_bit(val));
58         assert(!std::has_single_bit(val+1));
59 
60         T x = (T(1) << 63);
61         T y = (T(1) << 64);
62         assert( std::has_single_bit(x));
63         assert( std::has_single_bit(y));
64         assert(!std::has_single_bit(x + y));
65     }
66 #endif
67 
68     return true;
69 }
70 
71 int main(int, char**)
72 {
73     {
74     auto lambda = [](auto x) -> decltype(std::has_single_bit(x)) {};
75     using L = decltype(lambda);
76 
77     static_assert(!std::is_invocable_v<L, signed char>);
78     static_assert(!std::is_invocable_v<L, short>);
79     static_assert(!std::is_invocable_v<L, int>);
80     static_assert(!std::is_invocable_v<L, long>);
81     static_assert(!std::is_invocable_v<L, long long>);
82 #ifndef _LIBCPP_HAS_NO_INT128
83     static_assert(!std::is_invocable_v<L, __int128_t>);
84 #endif
85 
86     static_assert(!std::is_invocable_v<L, int8_t>);
87     static_assert(!std::is_invocable_v<L, int16_t>);
88     static_assert(!std::is_invocable_v<L, int32_t>);
89     static_assert(!std::is_invocable_v<L, int64_t>);
90     static_assert(!std::is_invocable_v<L, intmax_t>);
91     static_assert(!std::is_invocable_v<L, intptr_t>);
92     static_assert(!std::is_invocable_v<L, ptrdiff_t>);
93 
94     static_assert(!std::is_invocable_v<L, bool>);
95     static_assert(!std::is_invocable_v<L, char>);
96     static_assert(!std::is_invocable_v<L, wchar_t>);
97 #ifndef _LIBCPP_HAS_NO_CHAR8_T
98     static_assert(!std::is_invocable_v<L, char8_t>);
99 #endif
100     static_assert(!std::is_invocable_v<L, char16_t>);
101     static_assert(!std::is_invocable_v<L, char32_t>);
102 
103     static_assert(!std::is_invocable_v<L, A>);
104     static_assert(!std::is_invocable_v<L, A*>);
105     static_assert(!std::is_invocable_v<L, E1>);
106     static_assert(!std::is_invocable_v<L, E2>);
107     }
108 
109     static_assert(test<unsigned char>());
110     static_assert(test<unsigned short>());
111     static_assert(test<unsigned int>());
112     static_assert(test<unsigned long>());
113     static_assert(test<unsigned long long>());
114 #ifndef _LIBCPP_HAS_NO_INT128
115     static_assert(test<__uint128_t>());
116 #endif
117     static_assert(test<uint8_t>());
118     static_assert(test<uint16_t>());
119     static_assert(test<uint32_t>());
120     static_assert(test<uint64_t>());
121     static_assert(test<uintmax_t>());
122     static_assert(test<uintptr_t>());
123     static_assert(test<size_t>());
124 
125     test<unsigned char>();
126     test<unsigned short>();
127     test<unsigned int>();
128     test<unsigned long>();
129     test<unsigned long long>();
130 #ifndef _LIBCPP_HAS_NO_INT128
131     test<__uint128_t>();
132 #endif
133     test<uint8_t>();
134     test<uint16_t>();
135     test<uint32_t>();
136     test<uint64_t>();
137     test<uintmax_t>();
138     test<uintptr_t>();
139     test<size_t>();
140 
141     return 0;
142 }
143