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 // UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
10
11 // <chrono>
12 // class month;
13
14 // constexpr month operator-(const month& x, const months& y) noexcept;
15 // Returns: x + -y.
16 //
17 // constexpr months operator-(const month& x, const month& y) noexcept;
18 // Returns: If x.ok() == true and y.ok() == true, returns a value m in the range
19 // [months{0}, months{11}] satisfying y + m == x.
20 // Otherwise the value returned is unspecified.
21 // [Example: January - February == months{11}. —end example]
22
23 extern "C" int printf(const char *, ...);
24
25 #include <chrono>
26 #include <type_traits>
27 #include <cassert>
28
29 #include "test_macros.h"
30
31 template <typename M, typename Ms>
testConstexpr()32 constexpr bool testConstexpr()
33 {
34 {
35 M m{5};
36 Ms offset{3};
37 if (m - offset != M{2}) return false;
38 if (m - M{2} != offset) return false;
39 }
40
41 // Check the example
42 if (M{1} - M{2} != Ms{11}) return false;
43 return true;
44 }
45
46 #include <iostream>
47
main()48 int main()
49 {
50 using month = std::chrono::month;
51 using months = std::chrono::months;
52
53 ASSERT_NOEXCEPT(std::declval<month>() - std::declval<months>());
54 ASSERT_NOEXCEPT(std::declval<month>() - std::declval<month>());
55
56 ASSERT_SAME_TYPE(month , decltype(std::declval<month>() - std::declval<months>()));
57 ASSERT_SAME_TYPE(months, decltype(std::declval<month>() - std::declval<month> ()));
58
59 static_assert(testConstexpr<month, months>(), "");
60
61 month m{6};
62 for (unsigned i = 1; i <= 12; ++i)
63 {
64 month m1 = m - months{i};
65 // months off = m - month {i};
66 int exp = 6 - i;
67 if (exp < 1)
68 exp += 12;
69 assert(static_cast<unsigned>(m1) == static_cast<unsigned>(exp));
70 // assert(off.count() == static_cast<unsigned>(exp));
71 }
72 }
73