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// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
9
10// <mdspan>
11
12// template<class OtherIndexType, size_t... OtherExtents>
13// constexpr explicit(see below) extents(const extents<OtherIndexType, OtherExtents...>&) noexcept;
14//
15// Constraints:
16// * sizeof...(OtherExtents) == rank() is true.
17// * ((OtherExtents == dynamic_extent || Extents == dynamic_extent ||
18// OtherExtents == Extents) && ...) is true.
19//
20// Preconditions:
21// * other.extent(r) equals Er for each r for which Er is a static extent, and
22// * either
23// - sizeof...(OtherExtents) is zero, or
24// - other.extent(r) is representable as a value of type index_type for
25// every rank index r of other.
26//
27// Remarks: The expression inside explicit is equivalent to:
28// (((Extents != dynamic_extent) && (OtherExtents == dynamic_extent)) || ... ) ||
29// (numeric_limits<index_type>::max() < numeric_limits<OtherIndexType>::max())
30
31#include <cassert>
32#include <cstddef>
33#include <limits>
34#include <mdspan>
35#include <type_traits>
36
37template <class To, class From>
38constexpr void test_implicit_conversion(To dest, From src) {
39 assert(dest == src);
40}
41
42template <bool implicit, class To, class From>
43constexpr void test_conversion(From src) {
44 To dest(src);
45 assert(dest == src);
46 if constexpr (implicit) {
47 dest = src;
48 assert(dest == src);
49 test_implicit_conversion<To, From>(src, src);
50 }
51}
52
53template <class T1, class T2>
54constexpr void test_conversion() {
55 constexpr size_t D = std::dynamic_extent;
56 constexpr bool idx_convertible =
57 static_cast<size_t>(std::numeric_limits<T1>::max()) >= static_cast<size_t>(std::numeric_limits<T2>::max());
58
59 // clang-format off
60 test_conversion<idx_convertible && true, std::extents<T1>>(std::extents<T2>());
61 test_conversion<idx_convertible && true, std::extents<T1, D>>(std::extents<T2, D>(5));
62 test_conversion<idx_convertible && false, std::extents<T1, 5>>(std::extents<T2, D>(5));
63 test_conversion<idx_convertible && true, std::extents<T1, 5>>(std::extents<T2, 5>());
64 test_conversion<idx_convertible && false, std::extents<T1, 5, D>>(std::extents<T2, D, D>(5, 5));
65 test_conversion<idx_convertible && true, std::extents<T1, D, D>>(std::extents<T2, D, D>(5, 5));
66 test_conversion<idx_convertible && true, std::extents<T1, D, D>>(std::extents<T2, D, 7>(5));
67 test_conversion<idx_convertible && true, std::extents<T1, 5, 7>>(std::extents<T2, 5, 7>());
68 test_conversion<idx_convertible && false, std::extents<T1, 5, D, 8, D, D>>(std::extents<T2, D, D, 8, 9, 1>(5, 7));
69 test_conversion<idx_convertible && true, std::extents<T1, D, D, D, D, D>>(
70 std::extents<T2, D, D, D, D, D>(5, 7, 8, 9, 1));
71 test_conversion<idx_convertible && true, std::extents<T1, D, D, 8, 9, D>>(std::extents<T2, D, 7, 8, 9, 1>(5));
72 test_conversion<idx_convertible && true, std::extents<T1, 5, 7, 8, 9, 1>>(std::extents<T2, 5, 7, 8, 9, 1>());
73 // clang-format on
74}
75
76constexpr void test_no_implicit_conversion() {
77 constexpr size_t D = std::dynamic_extent;
78 // Sanity check that one static to dynamic conversion works
79 static_assert(std::is_constructible_v<std::extents<int, D>, std::extents<int, 5>>, "");
80 static_assert(std::is_convertible_v<std::extents<int, 5>, std::extents<int, D>>, "");
81
82 // Check that dynamic to static conversion only works explicitly only
83 static_assert(std::is_constructible_v<std::extents<int, 5>, std::extents<int, D>>, "");
84 static_assert(!std::is_convertible_v<std::extents<int, D>, std::extents<int, 5>>, "");
85
86 // Sanity check that one static to dynamic conversion works
87 static_assert(std::is_constructible_v<std::extents<int, D, 7>, std::extents<int, 5, 7>>, "");
88 static_assert(std::is_convertible_v<std::extents<int, 5, 7>, std::extents<int, D, 7>>, "");
89
90 // Check that dynamic to static conversion only works explicitly only
91 static_assert(std::is_constructible_v<std::extents<int, 5, 7>, std::extents<int, D, 7>>, "");
92 static_assert(!std::is_convertible_v<std::extents<int, D, 7>, std::extents<int, 5, 7>>, "");
93
94 // Sanity check that smaller index_type to larger index_type conversion works
95 static_assert(std::is_constructible_v<std::extents<size_t, 5>, std::extents<int, 5>>, "");
96 static_assert(std::is_convertible_v<std::extents<int, 5>, std::extents<size_t, 5>>, "");
97
98 // Check that larger index_type to smaller index_type conversion works explicitly only
99 static_assert(std::is_constructible_v<std::extents<int, 5>, std::extents<size_t, 5>>, "");
100 static_assert(!std::is_convertible_v<std::extents<size_t, 5>, std::extents<int, 5>>, "");
101}
102
103constexpr void test_rank_mismatch() {
104 constexpr size_t D = std::dynamic_extent;
105
106 static_assert(!std::is_constructible_v<std::extents<int, D>, std::extents<int>>, "");
107 static_assert(!std::is_constructible_v<std::extents<int>, std::extents<int, D, D>>, "");
108 static_assert(!std::is_constructible_v<std::extents<int, D>, std::extents<int, D, D>>, "");
109 static_assert(!std::is_constructible_v<std::extents<int, D, D, D>, std::extents<int, D, D>>, "");
110}
111
112constexpr void test_static_extent_mismatch() {
113 constexpr size_t D = std::dynamic_extent;
114
115 static_assert(!std::is_constructible_v<std::extents<int, D, 5>, std::extents<int, D, 4>>, "");
116 static_assert(!std::is_constructible_v<std::extents<int, 5>, std::extents<int, 4>>, "");
117 static_assert(!std::is_constructible_v<std::extents<int, 5, D>, std::extents<int, 4, D>>, "");
118}
119
120constexpr bool test() {
121 test_conversion<int, int>();
122 test_conversion<int, size_t>();
123 test_conversion<size_t, int>();
124 test_conversion<size_t, long>();
125 test_no_implicit_conversion();
126 test_rank_mismatch();
127 test_static_extent_mismatch();
128 return true;
129}
130
131int main(int, char**) {
132 test();
133 static_assert(test());
134
135 return 0;
136}
137

source code of libcxx/test/std/containers/views/mdspan/extents/conversion.pass.cpp