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 //
10 // UNSUPPORTED: c++98, c++03, c++11, c++14
11
12 // <numeric>
13
14 // template<class _M, class _N>
15 // constexpr common_type_t<_M,_N> gcd(_M __m, _N __n)
16
17 #include <numeric>
18 #include <cassert>
19 #include <cstdlib> // for rand()
20 #include <iostream>
21
22 constexpr struct {
23 int x;
24 int y;
25 int expect;
26 } Cases[] = {
27 {0, 0, 0},
28 {1, 0, 1},
29 {0, 1, 1},
30 {1, 1, 1},
31 {2, 3, 1},
32 {2, 4, 2},
33 {36, 17, 1},
34 {36, 18, 18}
35 };
36
37
38 template <typename Input1, typename Input2, typename Output>
test0(Input1 in1,Input2 in2,Output out)39 constexpr bool test0(Input1 in1, Input2 in2, Output out)
40 {
41 static_assert((std::is_same<Output, decltype(std::gcd(in1, in2))>::value), "" );
42 static_assert((std::is_same<Output, decltype(std::gcd(in2, in1))>::value), "" );
43 return out == std::gcd(in1, in2) ? true : (std::abort(), false);
44 }
45
46
47 template <typename Input1, typename Input2 = Input1>
do_test(int=0)48 constexpr bool do_test(int = 0)
49 {
50 using S1 = typename std::make_signed<Input1>::type;
51 using S2 = typename std::make_signed<Input2>::type;
52 using U1 = typename std::make_unsigned<Input1>::type;
53 using U2 = typename std::make_unsigned<Input2>::type;
54 bool accumulate = true;
55 for (auto TC : Cases) {
56 { // Test with two signed types
57 using Output = std::common_type_t<S1, S2>;
58 accumulate &= test0<S1, S2, Output>(TC.x, TC.y, TC.expect);
59 accumulate &= test0<S1, S2, Output>(-TC.x, TC.y, TC.expect);
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<S2, S1, Output>(TC.x, TC.y, TC.expect);
63 accumulate &= test0<S2, S1, 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 }
67 { // test with two unsigned types
68 using Output = std::common_type_t<U1, U2>;
69 accumulate &= test0<U1, U2, Output>(TC.x, TC.y, TC.expect);
70 accumulate &= test0<U2, U1, Output>(TC.x, TC.y, TC.expect);
71 }
72 { // Test with mixed signs
73 using Output = std::common_type_t<S1, U2>;
74 accumulate &= test0<S1, U2, Output>(TC.x, TC.y, TC.expect);
75 accumulate &= test0<U2, S1, Output>(TC.x, TC.y, TC.expect);
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 }
79 { // Test with mixed signs
80 using Output = std::common_type_t<S2, U1>;
81 accumulate &= test0<S2, U1, Output>(TC.x, TC.y, TC.expect);
82 accumulate &= test0<U1, S2, Output>(TC.x, TC.y, TC.expect);
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 }
86 }
87 return accumulate;
88 }
89
main()90 int main()
91 {
92 auto non_cce = std::rand(); // a value that can't possibly be constexpr
93
94 static_assert(do_test<signed char>(), "");
95 static_assert(do_test<short>(), "");
96 static_assert(do_test<int>(), "");
97 static_assert(do_test<long>(), "");
98 static_assert(do_test<long long>(), "");
99
100 assert(do_test<signed char>(non_cce));
101 assert(do_test<short>(non_cce));
102 assert(do_test<int>(non_cce));
103 assert(do_test<long>(non_cce));
104 assert(do_test<long long>(non_cce));
105
106 static_assert(do_test< int8_t>(), "");
107 static_assert(do_test<int16_t>(), "");
108 static_assert(do_test<int32_t>(), "");
109 static_assert(do_test<int64_t>(), "");
110
111 assert(do_test< int8_t>(non_cce));
112 assert(do_test<int16_t>(non_cce));
113 assert(do_test<int32_t>(non_cce));
114 assert(do_test<int64_t>(non_cce));
115
116 static_assert(do_test<signed char, int>(), "");
117 static_assert(do_test<int, signed char>(), "");
118 static_assert(do_test<short, int>(), "");
119 static_assert(do_test<int, short>(), "");
120 static_assert(do_test<int, long>(), "");
121 static_assert(do_test<long, int>(), "");
122 static_assert(do_test<int, long long>(), "");
123 static_assert(do_test<long long, int>(), "");
124
125 assert((do_test<signed char, int>(non_cce)));
126 assert((do_test<int, signed char>(non_cce)));
127 assert((do_test<short, int>(non_cce)));
128 assert((do_test<int, short>(non_cce)));
129 assert((do_test<int, long>(non_cce)));
130 assert((do_test<long, int>(non_cce)));
131 assert((do_test<int, long long>(non_cce)));
132 assert((do_test<long long, int>(non_cce)));
133
134 // LWG#2837
135 {
136 auto res = std::gcd((int64_t)1234, (int32_t)-2147483648);
137 static_assert( std::is_same<decltype(res), std::common_type<int64_t, int32_t>::type>::value, "");
138 assert(res == 2);
139 }
140 }
141