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
10 // <numeric>
11
12 // template<class _M, class _N>
13 // constexpr common_type_t<_M,_N> lcm(_M __m, _N __n)
14
15 #include <numeric>
16 #include <cassert>
17 #include <climits>
18 #include <cstdint>
19 #include <type_traits>
20 #include "test_macros.h"
21
22 constexpr struct {
23 int x;
24 int y;
25 int expect;
26 } Cases[] = {
27 {0, 0, 0},
28 {1, 0, 0},
29 {0, 1, 0},
30 {1, 1, 1},
31 {2, 3, 6},
32 {2, 4, 4},
33 {3, 17, 51},
34 {36, 18, 36}
35 };
36
37 template <typename Input1, typename Input2, typename Output>
test0(int in1,int in2,int out)38 constexpr bool test0(int in1, int in2, int out)
39 {
40 auto value1 = static_cast<Input1>(in1);
41 auto value2 = static_cast<Input2>(in2);
42 static_assert(std::is_same_v<Output, decltype(std::lcm(value1, value2))>, "");
43 static_assert(std::is_same_v<Output, decltype(std::lcm(value2, value1))>, "");
44 assert(static_cast<Output>(out) == std::lcm(value1, value2));
45 return true;
46 }
47
48
49 template <typename Input1, typename Input2 = Input1>
do_test(int=0)50 constexpr bool do_test(int = 0)
51 {
52 using S1 = std::make_signed_t<Input1>;
53 using S2 = std::make_signed_t<Input2>;
54 using U1 = std::make_unsigned_t<Input1>;
55 using U2 = std::make_unsigned_t<Input2>;
56 bool accumulate = true;
57 for (auto TC : Cases) {
58 { // Test with two signed types
59 using Output = std::common_type_t<S1, S2>;
60 accumulate &= test0<S1, S2, Output>(TC.x, TC.y, TC.expect);
61 accumulate &= test0<S1, S2, Output>(-TC.x, TC.y, TC.expect);
62 accumulate &= test0<S1, S2, Output>(TC.x, -TC.y, TC.expect);
63 accumulate &= test0<S1, S2, Output>(-TC.x, -TC.y, TC.expect);
64 accumulate &= test0<S2, S1, Output>(TC.x, TC.y, TC.expect);
65 accumulate &= test0<S2, S1, Output>(-TC.x, TC.y, TC.expect);
66 accumulate &= test0<S2, S1, Output>(TC.x, -TC.y, TC.expect);
67 accumulate &= test0<S2, S1, Output>(-TC.x, -TC.y, TC.expect);
68 }
69 { // test with two unsigned types
70 using Output = std::common_type_t<U1, U2>;
71 accumulate &= test0<U1, U2, Output>(TC.x, TC.y, TC.expect);
72 accumulate &= test0<U2, U1, Output>(TC.x, TC.y, TC.expect);
73 }
74 { // Test with mixed signs
75 using Output = std::common_type_t<S1, U2>;
76 accumulate &= test0<S1, U2, Output>(TC.x, TC.y, TC.expect);
77 accumulate &= test0<U2, S1, Output>(TC.x, TC.y, TC.expect);
78 accumulate &= test0<S1, U2, Output>(-TC.x, TC.y, TC.expect);
79 accumulate &= test0<U2, S1, Output>(TC.x, -TC.y, TC.expect);
80 }
81 { // Test with mixed signs
82 using Output = std::common_type_t<S2, U1>;
83 accumulate &= test0<S2, U1, Output>(TC.x, TC.y, TC.expect);
84 accumulate &= test0<U1, S2, Output>(TC.x, TC.y, TC.expect);
85 accumulate &= test0<S2, U1, Output>(-TC.x, TC.y, TC.expect);
86 accumulate &= test0<U1, S2, Output>(TC.x, -TC.y, TC.expect);
87 }
88 }
89 return accumulate;
90 }
91
main(int argc,char **)92 int main(int argc, char**)
93 {
94 int non_cce = argc; // a value that can't possibly be constexpr
95
96 static_assert(do_test<signed char>(), "");
97 static_assert(do_test<short>(), "");
98 static_assert(do_test<int>(), "");
99 static_assert(do_test<long>(), "");
100 static_assert(do_test<long long>(), "");
101
102 assert(do_test<signed char>(non_cce));
103 assert(do_test<short>(non_cce));
104 assert(do_test<int>(non_cce));
105 assert(do_test<long>(non_cce));
106 assert(do_test<long long>(non_cce));
107
108 static_assert(do_test<std::int8_t>(), "");
109 static_assert(do_test<std::int16_t>(), "");
110 static_assert(do_test<std::int32_t>(), "");
111 static_assert(do_test<std::int64_t>(), "");
112
113 assert(do_test<std::int8_t>(non_cce));
114 assert(do_test<std::int16_t>(non_cce));
115 assert(do_test<std::int32_t>(non_cce));
116 assert(do_test<std::int64_t>(non_cce));
117
118 static_assert(do_test<signed char, int>(), "");
119 static_assert(do_test<int, signed char>(), "");
120 static_assert(do_test<short, int>(), "");
121 static_assert(do_test<int, short>(), "");
122 static_assert(do_test<int, long>(), "");
123 static_assert(do_test<long, int>(), "");
124 static_assert(do_test<int, long long>(), "");
125 static_assert(do_test<long long, int>(), "");
126
127 assert((do_test<signed char, int>(non_cce)));
128 assert((do_test<int, signed char>(non_cce)));
129 assert((do_test<short, int>(non_cce)));
130 assert((do_test<int, short>(non_cce)));
131 assert((do_test<int, long>(non_cce)));
132 assert((do_test<long, int>(non_cce)));
133 assert((do_test<int, long long>(non_cce)));
134 assert((do_test<long long, int>(non_cce)));
135
136 // LWG#2837
137 {
138 auto res1 = std::lcm(static_cast<std::int64_t>(1234), INT32_MIN);
139 TEST_IGNORE_NODISCARD std::lcm(INT_MIN, 2UL); // this used to trigger UBSAN
140 static_assert(std::is_same_v<decltype(res1), std::int64_t>, "");
141 assert(res1 == 1324997410816LL);
142 }
143
144 return 0;
145 }
146