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