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// 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 <cstddef>
21#include <cstdint>
22#include <limits>
23#include <type_traits>
24
25#include "test_macros.h"
26
27struct A {};
28enum E1 : unsigned char { rEd };
29enum class E2 : unsigned char { red };
30
31template <class T>
32constexpr bool test()
33{
34 ASSERT_SAME_TYPE(decltype(std::bit_width(T())), int);
35 ASSERT_NOEXCEPT(std::bit_width(T()));
36 T max = std::numeric_limits<T>::max();
37
38 assert(std::bit_width(T(0)) == 0);
39 assert(std::bit_width(T(1)) == 1);
40 assert(std::bit_width(T(2)) == 2);
41 assert(std::bit_width(T(3)) == 2);
42 assert(std::bit_width(T(4)) == 3);
43 assert(std::bit_width(T(5)) == 3);
44 assert(std::bit_width(T(6)) == 3);
45 assert(std::bit_width(T(7)) == 3);
46 assert(std::bit_width(T(8)) == 4);
47 assert(std::bit_width(T(9)) == 4);
48 assert(std::bit_width(T(125)) == 7);
49 assert(std::bit_width(T(126)) == 7);
50 assert(std::bit_width(T(127)) == 7);
51 assert(std::bit_width(T(128)) == 8);
52 assert(std::bit_width(T(129)) == 8);
53 assert(std::bit_width(T(130)) == 8);
54 assert(std::bit_width(T(max - 1)) == std::numeric_limits<T>::digits);
55 assert(std::bit_width(max) == std::numeric_limits<T>::digits);
56
57#ifndef TEST_HAS_NO_INT128
58 if constexpr (std::is_same_v<T, __uint128_t>) {
59 T val = 128;
60 val <<= 32;
61 assert(std::bit_width(val-1) == 39);
62 assert(std::bit_width(val) == 40);
63 assert(std::bit_width(val+1) == 40);
64 val <<= 60;
65 assert(std::bit_width(val-1) == 99);
66 assert(std::bit_width(val) == 100);
67 assert(std::bit_width(val+1) == 100);
68 }
69#endif
70
71 return true;
72}
73
74int main(int, char**)
75{
76
77 {
78 auto lambda = [](auto x) -> decltype(std::bit_width(x)) {};
79 using L = decltype(lambda);
80
81 static_assert(!std::is_invocable_v<L, signed char>);
82 static_assert(!std::is_invocable_v<L, short>);
83 static_assert(!std::is_invocable_v<L, int>);
84 static_assert(!std::is_invocable_v<L, long>);
85 static_assert(!std::is_invocable_v<L, long long>);
86#ifndef TEST_HAS_NO_INT128
87 static_assert(!std::is_invocable_v<L, __int128_t>);
88#endif
89
90 static_assert(!std::is_invocable_v<L, std::int8_t>);
91 static_assert(!std::is_invocable_v<L, std::int16_t>);
92 static_assert(!std::is_invocable_v<L, std::int32_t>);
93 static_assert(!std::is_invocable_v<L, std::int64_t>);
94 static_assert(!std::is_invocable_v<L, std::intmax_t>);
95 static_assert(!std::is_invocable_v<L, std::intptr_t>);
96 static_assert(!std::is_invocable_v<L, std::ptrdiff_t>);
97
98 static_assert(!std::is_invocable_v<L, bool>);
99 static_assert(!std::is_invocable_v<L, char>);
100 static_assert(!std::is_invocable_v<L, wchar_t>);
101#ifndef TEST_HAS_NO_CHAR8_T
102 static_assert(!std::is_invocable_v<L, char8_t>);
103#endif
104 static_assert(!std::is_invocable_v<L, char16_t>);
105 static_assert(!std::is_invocable_v<L, char32_t>);
106
107 static_assert(!std::is_invocable_v<L, A>);
108 static_assert(!std::is_invocable_v<L, A*>);
109 static_assert(!std::is_invocable_v<L, E1>);
110 static_assert(!std::is_invocable_v<L, E2>);
111 }
112
113 static_assert(test<unsigned char>());
114 static_assert(test<unsigned short>());
115 static_assert(test<unsigned int>());
116 static_assert(test<unsigned long>());
117 static_assert(test<unsigned long long>());
118#ifndef TEST_HAS_NO_INT128
119 static_assert(test<__uint128_t>());
120#endif
121 static_assert(test<std::uint8_t>());
122 static_assert(test<std::uint16_t>());
123 static_assert(test<std::uint32_t>());
124 static_assert(test<std::uint64_t>());
125 static_assert(test<std::uintmax_t>());
126 static_assert(test<std::uintptr_t>());
127 static_assert(test<std::size_t>());
128
129 test<unsigned char>();
130 test<unsigned short>();
131 test<unsigned int>();
132 test<unsigned long>();
133 test<unsigned long long>();
134#ifndef TEST_HAS_NO_INT128
135 test<__uint128_t>();
136#endif
137 test<std::uint8_t>();
138 test<std::uint16_t>();
139 test<std::uint32_t>();
140 test<std::uint64_t>();
141 test<std::uintmax_t>();
142 test<std::uintptr_t>();
143 test<std::size_t>();
144
145 return 0;
146}
147

source code of libcxx/test/std/numerics/bit/bit.pow.two/bit_width.pass.cpp