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83ffe9cd | 1 | // Copyright (C) 2018-2023 Free Software Foundation, Inc. |
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2 | // |
3 | // This file is part of the GNU ISO C++ Library. This library is free | |
4 | // software; you can redistribute it and/or modify it under the | |
5 | // terms of the GNU General Public License as published by the | |
6 | // Free Software Foundation; either version 3, or (at your option) | |
7 | // any later version. | |
8 | ||
9 | // This library is distributed in the hope that it will be useful, | |
10 | // but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | // GNU General Public License for more details. | |
13 | ||
14 | // You should have received a copy of the GNU General Public License along | |
15 | // with this library; see the file COPYING3. If not see | |
16 | // <http://www.gnu.org/licenses/>. | |
17 | ||
8ccae163 | 18 | // { dg-do compile { target c++20 } } |
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19 | |
20 | #include <bit> | |
c03b53da | 21 | #include <limits> |
f3e91052 | 22 | |
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23 | template<typename T> |
24 | constexpr T max = std::numeric_limits<T>::max(); | |
25 | // Largest representable power of two (i.e. has most significant bit set) | |
26 | template<typename T> | |
27 | constexpr T maxpow2 = T(1) << (std::numeric_limits<T>::digits - 1); | |
28 | ||
9866abe3 | 29 | // Detect whether std::bit_ceil(N) is a constant expression. |
281ab2fb | 30 | template<auto N, typename = void> |
9866abe3 | 31 | struct bit_ceil_valid |
281ab2fb JW |
32 | : std::false_type { }; |
33 | ||
34 | template<auto N> | |
9866abe3 | 35 | struct bit_ceil_valid<N, std::void_t<char[(std::bit_ceil(N), 1)]>> |
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36 | : std::true_type { }; |
37 | ||
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38 | template<typename UInt> |
39 | constexpr auto | |
40 | test(UInt x) | |
9866abe3 | 41 | -> decltype(std::bit_ceil(x)) |
f3e91052 | 42 | { |
9866abe3 | 43 | static_assert( noexcept(std::bit_ceil(x)) ); |
f3e91052 | 44 | |
9866abe3 JW |
45 | static_assert( std::bit_ceil(UInt(0)) == 1 ); |
46 | static_assert( std::bit_ceil(UInt(1)) == 1 ); | |
47 | static_assert( std::bit_ceil(UInt(2)) == 2 ); | |
48 | static_assert( std::bit_ceil(UInt(3)) == 4 ); | |
49 | static_assert( std::bit_ceil(UInt(4)) == 4 ); | |
50 | static_assert( std::bit_ceil(UInt(0x11)) == 0x20 ); | |
51 | static_assert( std::bit_ceil(UInt(0x20)) == 0x20 ); | |
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52 | |
53 | if constexpr (std::numeric_limits<UInt>::digits > 8) | |
54 | { | |
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55 | static_assert( std::bit_ceil(UInt(0x201)) == 0x400 ); |
56 | static_assert( std::bit_ceil(UInt(0x8ff)) == 0x1000 ); | |
57 | static_assert( std::bit_ceil(UInt(0x1000)) == 0x1000 ); | |
f3e91052 JW |
58 | } |
59 | ||
60 | if constexpr (std::numeric_limits<UInt>::digits > 32) | |
61 | { | |
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62 | static_assert( std::bit_ceil(UInt(0xabcdef)) == 0x1000000 ); |
63 | static_assert( std::bit_ceil(UInt(0x1000000)) == 0x1000000 ); | |
64 | static_assert( std::bit_ceil(UInt(0x1000001)) == 0x2000000 ); | |
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65 | } |
66 | ||
67 | if constexpr (std::numeric_limits<UInt>::digits > 64) | |
68 | { | |
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69 | static_assert( std::bit_ceil(UInt(1) << 64) == (UInt(1) << 64) ); |
70 | static_assert( std::bit_ceil(UInt(3) << 64) == (UInt(4) << 64) ); | |
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71 | } |
72 | ||
281ab2fb | 73 | constexpr UInt msb = maxpow2<UInt>; |
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74 | static_assert( bit_ceil_valid<msb>() ); |
75 | static_assert( std::bit_ceil( msb ) == msb ); | |
76 | static_assert( std::bit_ceil( UInt(msb - 1) ) == msb ); | |
77 | static_assert( std::bit_ceil( UInt(msb - 2) ) == msb ); | |
78 | static_assert( std::bit_ceil( UInt(msb - 3) ) == msb ); | |
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79 | |
80 | // P1355R2: not a constant expression if the result is not representable | |
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81 | static_assert( !bit_ceil_valid<UInt(msb + 1)>() ); |
82 | static_assert( !bit_ceil_valid<max<UInt>>() ); | |
83 | static_assert( !bit_ceil_valid<UInt(max<UInt> - 1)>() ); | |
84 | static_assert( !bit_ceil_valid<UInt(max<UInt> - 2)>() ); | |
2fb17d2d | 85 | |
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86 | return true; |
87 | } | |
88 | ||
89 | static_assert( test( (unsigned char)0 ) ); | |
90 | static_assert( test( (unsigned short)0 ) ); | |
91 | static_assert( test( (unsigned int)0 ) ); | |
92 | static_assert( test( (unsigned long)0 ) ); | |
93 | static_assert( test( (unsigned long long)0 ) ); | |
94 | ||
9866abe3 | 95 | // std::bit_ceil(T) shall not participate in overload resolution |
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96 | // unless T is an unsigned integer type. |
97 | struct X { constexpr bool did_not_match() { return true; } }; | |
98 | constexpr X test(...) { return X{}; } | |
99 | static_assert( test( (bool)0 ).did_not_match() ); | |
100 | static_assert( test( (char)0 ).did_not_match() ); | |
101 | static_assert( test( (int)0 ).did_not_match() ); | |
102 | static_assert( test( (char16_t)0 ).did_not_match() ); | |
103 | static_assert( test( (float)0 ).did_not_match() ); | |
104 | static_assert( test( (void*)0 ).did_not_match() ); | |
105 | static_assert( test( X{} ).did_not_match() ); | |
106 | enum E : unsigned { e }; | |
107 | static_assert( test( e ).did_not_match() ); | |
108 | ||
29a9de9b | 109 | #if !defined(__STRICT_ANSI__) && defined __SIZEOF_INT128__ |
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110 | static_assert( test( (unsigned __int128)0 ) ); |
111 | static_assert( test( (__int128)0 ).did_not_match() ); | |
112 | #endif | |
113 | #if defined(__GLIBCXX_TYPE_INT_N_0) | |
114 | static_assert( test( (unsigned __GLIBCXX_TYPE_INT_N_0)0 ) ); | |
115 | static_assert( test( (__GLIBCXX_TYPE_INT_N_0)0 ).did_not_match() ); | |
116 | #endif | |
117 | #if defined(__GLIBCXX_TYPE_INT_N_1) | |
118 | static_assert( test( (unsigned __GLIBCXX_TYPE_INT_N_1)0 ) ); | |
119 | static_assert( test( (__GLIBCXX_TYPE_INT_N_1)0 ).did_not_match() ); | |
120 | #endif | |
121 | #if defined(__GLIBCXX_TYPE_INT_N_2) | |
122 | static_assert( test( (unsigned __GLIBCXX_TYPE_INT_N_2)0 ) ); | |
123 | static_assert( test( (__GLIBCXX_TYPE_INT_N_2)0 ).did_not_match() ); | |
124 | #endif | |
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125 | #if defined(__GLIBCXX_TYPE_INT_N_3) |
126 | static_assert( test( (unsigned __GLIBCXX_TYPE_INT_N_3)0 ) ); | |
127 | static_assert( test( (__GLIBCXX_TYPE_INT_N_3)0 ).did_not_match() ); | |
128 | #endif | |
129 | ||
130 | #include <cstddef> | |
131 | static_assert( test( (std::byte)0 ).did_not_match() ); |