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 
11 // <numeric>
12 
13 // template<class _M, class _N>
14 // constexpr common_type_t<_M,_N> gcd(_M __m, _N __n)
15 
16 #include <numeric>
17 #include <cassert>
18 #include <climits>
19 #include <cstdint>
20 #include <type_traits>
21 
22 #include "test_macros.h"
23 
24 constexpr struct {
25   int x;
26   int y;
27   int expect;
28 } Cases[] = {
29     {0, 0, 0},
30     {1, 0, 1},
31     {0, 1, 1},
32     {1, 1, 1},
33     {2, 3, 1},
34     {2, 4, 2},
35     {36, 17, 1},
36     {36, 18, 18}
37 };
38 
39 
40 template <typename Input1, typename Input2, typename Output>
test0(int in1,int in2,int out)41 constexpr bool test0(int in1, int in2, int out)
42 {
43     auto value1 = static_cast<Input1>(in1);
44     auto value2 = static_cast<Input2>(in2);
45     static_assert(std::is_same_v<Output, decltype(std::gcd(value1, value2))>, "");
46     static_assert(std::is_same_v<Output, decltype(std::gcd(value2, value1))>, "");
47     assert(static_cast<Output>(out) == std::gcd(value1, value2));
48     return true;
49 }
50 
51 
52 template <typename Input1, typename Input2 = Input1>
do_test(int=0)53 constexpr bool do_test(int = 0)
54 {
55     using S1 = std::make_signed_t<Input1>;
56     using S2 = std::make_signed_t<Input2>;
57     using U1 = std::make_unsigned_t<Input1>;
58     using U2 = std::make_unsigned_t<Input2>;
59     bool accumulate = true;
60     for (auto TC : Cases) {
61         { // Test with two signed types
62             using Output = std::common_type_t<S1, S2>;
63             accumulate &= test0<S1, S2, Output>(TC.x, TC.y, TC.expect);
64             accumulate &= test0<S1, S2, Output>(-TC.x, TC.y, TC.expect);
65             accumulate &= test0<S1, S2, Output>(TC.x, -TC.y, TC.expect);
66             accumulate &= test0<S1, S2, Output>(-TC.x, -TC.y, TC.expect);
67             accumulate &= test0<S2, S1, Output>(TC.x, TC.y, TC.expect);
68             accumulate &= test0<S2, S1, Output>(-TC.x, TC.y, TC.expect);
69             accumulate &= test0<S2, S1, Output>(TC.x, -TC.y, TC.expect);
70             accumulate &= test0<S2, S1, Output>(-TC.x, -TC.y, TC.expect);
71         }
72         { // test with two unsigned types
73             using Output = std::common_type_t<U1, U2>;
74             accumulate &= test0<U1, U2, Output>(TC.x, TC.y, TC.expect);
75             accumulate &= test0<U2, U1, Output>(TC.x, TC.y, TC.expect);
76         }
77         { // Test with mixed signs
78             using Output = std::common_type_t<S1, U2>;
79             accumulate &= test0<S1, U2, Output>(TC.x, TC.y, TC.expect);
80             accumulate &= test0<U2, S1, Output>(TC.x, TC.y, TC.expect);
81             accumulate &= test0<S1, U2, Output>(-TC.x, TC.y, TC.expect);
82             accumulate &= test0<U2, S1, Output>(TC.x, -TC.y, TC.expect);
83         }
84         { // Test with mixed signs
85             using Output = std::common_type_t<S2, U1>;
86             accumulate &= test0<S2, U1, Output>(TC.x, TC.y, TC.expect);
87             accumulate &= test0<U1, S2, Output>(TC.x, TC.y, TC.expect);
88             accumulate &= test0<S2, U1, Output>(-TC.x, TC.y, TC.expect);
89             accumulate &= test0<U1, S2, Output>(TC.x, -TC.y, TC.expect);
90         }
91     }
92     return accumulate;
93 }
94 
main(int argc,char **)95 int main(int argc, char**)
96 {
97     int non_cce = argc; // a value that can't possibly be constexpr
98 
99     static_assert(do_test<signed char>(), "");
100     static_assert(do_test<short>(), "");
101     static_assert(do_test<int>(), "");
102     static_assert(do_test<long>(), "");
103     static_assert(do_test<long long>(), "");
104 
105     assert(do_test<signed char>(non_cce));
106     assert(do_test<short>(non_cce));
107     assert(do_test<int>(non_cce));
108     assert(do_test<long>(non_cce));
109     assert(do_test<long long>(non_cce));
110 
111     static_assert(do_test<std::int8_t>(), "");
112     static_assert(do_test<std::int16_t>(), "");
113     static_assert(do_test<std::int32_t>(), "");
114     static_assert(do_test<std::int64_t>(), "");
115 
116     assert(do_test<std::int8_t>(non_cce));
117     assert(do_test<std::int16_t>(non_cce));
118     assert(do_test<std::int32_t>(non_cce));
119     assert(do_test<std::int64_t>(non_cce));
120 
121     static_assert(do_test<signed char, int>(), "");
122     static_assert(do_test<int, signed char>(), "");
123     static_assert(do_test<short, int>(), "");
124     static_assert(do_test<int, short>(), "");
125     static_assert(do_test<int, long>(), "");
126     static_assert(do_test<long, int>(), "");
127     static_assert(do_test<int, long long>(), "");
128     static_assert(do_test<long long, int>(), "");
129 
130     assert((do_test<signed char, int>(non_cce)));
131     assert((do_test<int, signed char>(non_cce)));
132     assert((do_test<short, int>(non_cce)));
133     assert((do_test<int, short>(non_cce)));
134     assert((do_test<int, long>(non_cce)));
135     assert((do_test<long, int>(non_cce)));
136     assert((do_test<int, long long>(non_cce)));
137     assert((do_test<long long, int>(non_cce)));
138 
139 //  LWG#2837
140     {
141     auto res = std::gcd(static_cast<std::int64_t>(1234), INT32_MIN);
142     static_assert(std::is_same_v<decltype(res), std::int64_t>, "");
143     assert(res == 2);
144     }
145 
146   return 0;
147 }
148