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++98, 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 <cstdlib> 20 #include <type_traits> 21 #include "test_macros.h" 22 23 constexpr struct { 24 int x; 25 int y; 26 int expect; 27 } Cases[] = { 28 {0, 0, 0}, 29 {1, 0, 0}, 30 {0, 1, 0}, 31 {1, 1, 1}, 32 {2, 3, 6}, 33 {2, 4, 4}, 34 {3, 17, 51}, 35 {36, 18, 36} 36 }; 37 38 template <typename Input1, typename Input2, typename Output> 39 constexpr bool test0(int in1, int in2, int out) 40 { 41 auto value1 = static_cast<Input1>(in1); 42 auto value2 = static_cast<Input2>(in2); 43 static_assert(std::is_same_v<Output, decltype(std::lcm(value1, value2))>, ""); 44 static_assert(std::is_same_v<Output, decltype(std::lcm(value2, value1))>, ""); 45 assert(static_cast<Output>(out) == std::lcm(value1, value2)); 46 return true; 47 } 48 49 50 template <typename Input1, typename Input2 = Input1> 51 constexpr bool do_test(int = 0) 52 { 53 using S1 = std::make_signed_t<Input1>; 54 using S2 = std::make_signed_t<Input2>; 55 using U1 = std::make_unsigned_t<Input1>; 56 using U2 = std::make_unsigned_t<Input2>; 57 bool accumulate = true; 58 for (auto TC : Cases) { 59 { // Test with two signed types 60 using Output = std::common_type_t<S1, S2>; 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<S1, S2, 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 accumulate &= test0<S2, S1, Output>(-TC.x, -TC.y, TC.expect); 69 } 70 { // test with two unsigned types 71 using Output = std::common_type_t<U1, U2>; 72 accumulate &= test0<U1, U2, Output>(TC.x, TC.y, TC.expect); 73 accumulate &= test0<U2, U1, Output>(TC.x, TC.y, TC.expect); 74 } 75 { // Test with mixed signs 76 using Output = std::common_type_t<S1, U2>; 77 accumulate &= test0<S1, U2, Output>(TC.x, TC.y, TC.expect); 78 accumulate &= test0<U2, S1, Output>(TC.x, TC.y, TC.expect); 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 } 82 { // Test with mixed signs 83 using Output = std::common_type_t<S2, U1>; 84 accumulate &= test0<S2, U1, Output>(TC.x, TC.y, TC.expect); 85 accumulate &= test0<U1, S2, Output>(TC.x, TC.y, TC.expect); 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 } 89 } 90 return accumulate; 91 } 92 93 int main(int, char**) 94 { 95 auto non_cce = std::rand(); // a value that can't possibly be constexpr 96 97 static_assert(do_test<signed char>(), ""); 98 static_assert(do_test<short>(), ""); 99 static_assert(do_test<int>(), ""); 100 static_assert(do_test<long>(), ""); 101 static_assert(do_test<long long>(), ""); 102 103 assert(do_test<signed char>(non_cce)); 104 assert(do_test<short>(non_cce)); 105 assert(do_test<int>(non_cce)); 106 assert(do_test<long>(non_cce)); 107 assert(do_test<long long>(non_cce)); 108 109 static_assert(do_test<std::int8_t>(), ""); 110 static_assert(do_test<std::int16_t>(), ""); 111 static_assert(do_test<std::int32_t>(), ""); 112 static_assert(do_test<std::int64_t>(), ""); 113 114 assert(do_test<std::int8_t>(non_cce)); 115 assert(do_test<std::int16_t>(non_cce)); 116 assert(do_test<std::int32_t>(non_cce)); 117 assert(do_test<std::int64_t>(non_cce)); 118 119 static_assert(do_test<signed char, int>(), ""); 120 static_assert(do_test<int, signed char>(), ""); 121 static_assert(do_test<short, int>(), ""); 122 static_assert(do_test<int, short>(), ""); 123 static_assert(do_test<int, long>(), ""); 124 static_assert(do_test<long, int>(), ""); 125 static_assert(do_test<int, long long>(), ""); 126 static_assert(do_test<long long, int>(), ""); 127 128 assert((do_test<signed char, int>(non_cce))); 129 assert((do_test<int, signed char>(non_cce))); 130 assert((do_test<short, int>(non_cce))); 131 assert((do_test<int, short>(non_cce))); 132 assert((do_test<int, long>(non_cce))); 133 assert((do_test<long, int>(non_cce))); 134 assert((do_test<int, long long>(non_cce))); 135 assert((do_test<long long, int>(non_cce))); 136 137 // LWG#2837 138 { 139 auto res1 = std::lcm(static_cast<std::int64_t>(1234), INT32_MIN); 140 TEST_IGNORE_NODISCARD std::lcm(INT_MIN, 2UL); // this used to trigger UBSAN 141 static_assert(std::is_same_v<decltype(res1), std::int64_t>, ""); 142 assert(res1 == 1324997410816LL); 143 } 144 145 return 0; 146 } 147