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 int bit_width(T x) noexcept;
13
14 // Constraints: T is an unsigned integer type
15 // Returns: If x == 0, 0; otherwise one plus the base-2 logarithm of x, with any fractional part discarded.
16
17
18 #include <bit>
19 #include <cassert>
20 #include <cstdint>
21 #include <type_traits>
22
23 #include "test_macros.h"
24
25 struct A {};
26 enum E1 : unsigned char { rEd };
27 enum class E2 : unsigned char { red };
28
29 template <class T>
test()30 constexpr bool test()
31 {
32 ASSERT_SAME_TYPE(decltype(std::bit_width(T())), int);
33 ASSERT_NOEXCEPT(std::bit_width(T()));
34 T max = std::numeric_limits<T>::max();
35
36 assert(std::bit_width(T(0)) == 0);
37 assert(std::bit_width(T(1)) == 1);
38 assert(std::bit_width(T(2)) == 2);
39 assert(std::bit_width(T(3)) == 2);
40 assert(std::bit_width(T(4)) == 3);
41 assert(std::bit_width(T(5)) == 3);
42 assert(std::bit_width(T(6)) == 3);
43 assert(std::bit_width(T(7)) == 3);
44 assert(std::bit_width(T(8)) == 4);
45 assert(std::bit_width(T(9)) == 4);
46 assert(std::bit_width(T(125)) == 7);
47 assert(std::bit_width(T(126)) == 7);
48 assert(std::bit_width(T(127)) == 7);
49 assert(std::bit_width(T(128)) == 8);
50 assert(std::bit_width(T(129)) == 8);
51 assert(std::bit_width(T(130)) == 8);
52 assert(std::bit_width(T(max - 1)) == std::numeric_limits<T>::digits);
53 assert(std::bit_width(max) == std::numeric_limits<T>::digits);
54
55 #ifndef TEST_HAS_NO_INT128
56 if constexpr (std::is_same_v<T, __uint128_t>) {
57 T val = 128;
58 val <<= 32;
59 assert(std::bit_width(val-1) == 39);
60 assert(std::bit_width(val) == 40);
61 assert(std::bit_width(val+1) == 40);
62 val <<= 60;
63 assert(std::bit_width(val-1) == 99);
64 assert(std::bit_width(val) == 100);
65 assert(std::bit_width(val+1) == 100);
66 }
67 #endif
68
69 return true;
70 }
71
main(int,char **)72 int main(int, char**)
73 {
74
75 {
76 auto lambda = [](auto x) -> decltype(std::bit_width(x)) {};
77 using L = decltype(lambda);
78
79 static_assert(!std::is_invocable_v<L, signed char>);
80 static_assert(!std::is_invocable_v<L, short>);
81 static_assert(!std::is_invocable_v<L, int>);
82 static_assert(!std::is_invocable_v<L, long>);
83 static_assert(!std::is_invocable_v<L, long long>);
84 #ifndef TEST_HAS_NO_INT128
85 static_assert(!std::is_invocable_v<L, __int128_t>);
86 #endif
87
88 static_assert(!std::is_invocable_v<L, int8_t>);
89 static_assert(!std::is_invocable_v<L, int16_t>);
90 static_assert(!std::is_invocable_v<L, int32_t>);
91 static_assert(!std::is_invocable_v<L, int64_t>);
92 static_assert(!std::is_invocable_v<L, intmax_t>);
93 static_assert(!std::is_invocable_v<L, intptr_t>);
94 static_assert(!std::is_invocable_v<L, ptrdiff_t>);
95
96 static_assert(!std::is_invocable_v<L, bool>);
97 static_assert(!std::is_invocable_v<L, char>);
98 static_assert(!std::is_invocable_v<L, wchar_t>);
99 #ifndef TEST_HAS_NO_CHAR8_T
100 static_assert(!std::is_invocable_v<L, char8_t>);
101 #endif
102 static_assert(!std::is_invocable_v<L, char16_t>);
103 static_assert(!std::is_invocable_v<L, char32_t>);
104
105 static_assert(!std::is_invocable_v<L, A>);
106 static_assert(!std::is_invocable_v<L, A*>);
107 static_assert(!std::is_invocable_v<L, E1>);
108 static_assert(!std::is_invocable_v<L, E2>);
109 }
110
111 static_assert(test<unsigned char>());
112 static_assert(test<unsigned short>());
113 static_assert(test<unsigned int>());
114 static_assert(test<unsigned long>());
115 static_assert(test<unsigned long long>());
116 #ifndef TEST_HAS_NO_INT128
117 static_assert(test<__uint128_t>());
118 #endif
119 static_assert(test<uint8_t>());
120 static_assert(test<uint16_t>());
121 static_assert(test<uint32_t>());
122 static_assert(test<uint64_t>());
123 static_assert(test<uintmax_t>());
124 static_assert(test<uintptr_t>());
125 static_assert(test<size_t>());
126
127 test<unsigned char>();
128 test<unsigned short>();
129 test<unsigned int>();
130 test<unsigned long>();
131 test<unsigned long long>();
132 #ifndef TEST_HAS_NO_INT128
133 test<__uint128_t>();
134 #endif
135 test<uint8_t>();
136 test<uint16_t>();
137 test<uint32_t>();
138 test<uint64_t>();
139 test<uintmax_t>();
140 test<uintptr_t>();
141 test<size_t>();
142
143 return 0;
144 }
145