1/* Unit testing for outcomes
2(C) 2013-2024 Niall Douglas <http://www.nedproductions.biz/> (9 commits)
3
4
5Boost Software License - Version 1.0 - August 17th, 2003
6
7Permission is hereby granted, free of charge, to any person or organization
8obtaining a copy of the software and accompanying documentation covered by
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10execute, and transmit the Software, and to prepare derivative works of the
11Software, and to permit third-parties to whom the Software is furnished to
12do so, all subject to the following:
13
14The copyright notices in the Software and this entire statement, including
15the above license grant, this restriction and the following disclaimer,
16must be included in all copies of the Software, in whole or in part, and
17all derivative works of the Software, unless such copies or derivative
18works are solely in the form of machine-executable object code generated by
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20
21THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
22IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
23FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
24SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
25FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
26ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
27DEALINGS IN THE SOFTWARE.
28*/
29
30#include <boost/outcome.hpp>
31#include <boost/test/unit_test.hpp>
32#include <boost/test/unit_test_monitor.hpp>
33
34#if __cplusplus >= 201700 || _HAS_CXX17
35// Match LiteralType, even on C++ 17 and later
36template <class T> struct is_literal_type
37{
38 static constexpr bool value = //
39 std::is_void<T>::value //
40 || std::is_scalar<T>::value //
41 || std::is_reference<T>::value //
42 // leave out is_array for simplicity
43 || (std::is_class<T>::value && std::is_trivially_destructible<T>::value
44 // how does one detect if a type has at least one constexpr constructor without Reflection???
45 ) // leave out union for simplicity
46 ;
47};
48#else
49template <class T> using is_literal_type = std::is_literal_type<T>;
50#endif
51
52BOOST_OUTCOME_AUTO_TEST_CASE(works_outcome_constexpr, "Tests that outcome works as intended in a constexpr evaluation context")
53{
54 using namespace BOOST_OUTCOME_V2_NAMESPACE;
55
56 static_assert(is_literal_type<result<int, void, void>>::value, "result<int, void, void> is not a literal type!");
57 static_assert(is_literal_type<outcome<int, void, void>>::value, "outcome<int, void, void> is not a literal type!");
58
59 // Unfortunately result<T> can never be a literal type as error_code can never be literal
60 //
61 // It can however be trivially destructible as error_code is trivially destructible. That
62 // makes possible lots of compiler optimisations
63 static_assert(std::is_trivially_destructible<result<int>>::value, "result<int> is not trivially destructible!");
64 static_assert(std::is_trivially_destructible<result<void>>::value, "result<void> is not trivially destructible!");
65
66 // outcome<T> default has no trivial operations, but if configured it can become so
67 static_assert(std::is_trivially_destructible<outcome<int, boost::system::error_code, void>>::value,
68 "outcome<int, boost::system::error_code, void> is not trivially destructible!");
69
70 {
71 // Test compatible results can be constructed from one another
72 constexpr result<int, long> g(in_place_type<int>, 5);
73 constexpr result<long, int> g2(g);
74 static_assert(g.has_value(), "");
75 static_assert(!g.has_error(), "");
76 static_assert(g.assume_value() == 5, ""); // value() with UDT E won't compile
77 static_assert(g2.has_value(), "");
78 static_assert(!g2.has_error(), "");
79 static_assert(g2.assume_value() == 5, ""); // value() with UDT E won't compile
80 constexpr result<void, int> g3(in_place_type<void>);
81 constexpr result<long, int> g4(g3);
82 constexpr result<int, void> g5(in_place_type<void>);
83 constexpr result<long, int> g6(g5);
84 (void) g4;
85 (void) g6;
86
87 // Test void
88 constexpr result<void, int> h(in_place_type<void>);
89 static_assert(h.has_value(), "");
90 constexpr result<int, void> h2(in_place_type<void>);
91 static_assert(!h2.has_value(), "");
92 static_assert(h2.has_error(), "");
93
94 // Test const
95 constexpr result<const int, void> i(5);
96 constexpr result<const int, void> i2(i);
97 (void) i2;
98 }
99 {
100 // Test compatible outcomes can be constructed from one another
101 constexpr outcome<int, long, char *> g(in_place_type<int>, 5);
102 constexpr outcome<long, int, const char *> g2(g);
103 static_assert(g.has_value(), "");
104 static_assert(!g.has_error(), "");
105 static_assert(!g.has_exception(), "");
106 static_assert(g.assume_value() == 5, ""); // value() with UDT E won't compile
107 static_assert(g2.has_value(), "");
108 static_assert(!g2.has_error(), "");
109 static_assert(!g2.has_exception(), "");
110 static_assert(g2.assume_value() == 5, ""); // value() with UDT E won't compile
111 constexpr outcome<void, int, char *> g3(in_place_type<void>);
112 constexpr outcome<long, int, const char *> g4(g3);
113 constexpr outcome<int, void, char *> g5(in_place_type<void>);
114 constexpr outcome<long, int, const char *> g6(g5);
115 (void) g4;
116 (void) g6;
117 }
118}
119

source code of boost/libs/outcome/test/tests/constexpr.cpp