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 // Test construction from span:
13 //
14 // template<class OtherIndexType, size_t N>
15 // constexpr explicit(N != rank_dynamic()) extents(span<OtherIndexType, N> exts) noexcept;
16 //
17 // Constraints:
18 // * is_convertible_v<const OtherIndexType&, index_type> is true,
19 // * is_nothrow_constructible_v<index_type, const OtherIndexType&> is true, and
20 // * N == rank_dynamic() || N == rank() is true.
21 //
22 // Preconditions:
23 // * If N != rank_dynamic() is true, exts[r] equals Er for each r for which
24 // Er is a static extent, and
25 // * either
26 // - N is zero, or
27 // - exts[r] is nonnegative and is representable as a value of type index_type
28 // for every rank index r.
29 //
30
31 #include <mdspan>
32 #include <cassert>
33 #include <array>
34 #include <span>
35 #include <type_traits>
36
37 #include "../ConvertibleToIntegral.h"
38 #include "CtorTestCombinations.h"
39 #include "test_macros.h"
40
41 struct SpanCtorTest {
42 template <class E, class T, size_t N, class Extents, size_t... Indices>
test_constructionSpanCtorTest43 static constexpr void test_construction(std::array<T, N> all_ext, Extents ext, std::index_sequence<Indices...>) {
44 ASSERT_NOEXCEPT(E(ext));
45 if constexpr (N == E::rank_dynamic()) {
46 test_implicit_construction_call<E>(std::span(ext), all_ext);
47 }
48 test_runtime_observers(E(std::span(ext)), all_ext);
49 }
50 };
51
52 template <class E>
53 struct implicit_construction {
54 bool value;
implicit_constructionimplicit_construction55 implicit_construction(E) : value(true) {}
56 template <class T>
implicit_constructionimplicit_construction57 implicit_construction(T) : value(false) {}
58 };
59
main(int,char **)60 int main(int, char**) {
61 test_index_type_combo<SpanCtorTest>();
62 static_assert(test_index_type_combo<SpanCtorTest>());
63
64 constexpr size_t D = std::dynamic_extent;
65 using E = std::extents<int, 1, D, 3, D>;
66
67 // check can't construct from too few arguments
68 static_assert(!std::is_constructible_v<E, std::span<int, 1>>, "extents constructible from illegal arguments");
69 // check can't construct from rank_dynamic < #args < rank
70 static_assert(!std::is_constructible_v<E, std::span<int, 3>>, "extents constructible from illegal arguments");
71 // check can't construct from too many arguments
72 static_assert(!std::is_constructible_v<E, std::span<int, 5>>, "extents constructible from illegal arguments");
73
74 // test implicit construction fails from span and array if all extents are given
75 std::array a5{3, 4, 5, 6, 7};
76 std::span<int, 5> s5(a5.data(), 5);
77 // check that explicit construction works, i.e. no error
78 static_assert(std::is_constructible_v< std::extents<int, D, D, 5, D, D>, decltype(s5)>,
79 "extents unexpectedly not constructible");
80 // check that implicit construction doesn't work
81 assert((implicit_construction<std::extents<int, D, D, 5, D, D>>(s5).value == false));
82
83 // test construction fails from types not convertible to index_type but convertible to other integer types
84 static_assert(std::is_convertible_v<IntType, int>, "Test helper IntType unexpectedly not convertible to int");
85 static_assert(!std::is_constructible_v< std::extents<unsigned long, D>, std::span<IntType, 1>>,
86 "extents constructible from illegal arguments");
87
88 // index_type is not nothrow constructible
89 static_assert(std::is_convertible_v<IntType, unsigned char>);
90 static_assert(std::is_convertible_v<const IntType&, unsigned char>);
91 static_assert(!std::is_nothrow_constructible_v<unsigned char, const IntType&>);
92 static_assert(!std::is_constructible_v<std::dextents<unsigned char, 2>, std::span<IntType, 2>>);
93
94 // convertible from non-const to index_type but not from const
95 static_assert(std::is_convertible_v<IntTypeNC, int>);
96 static_assert(!std::is_convertible_v<const IntTypeNC&, int>);
97 static_assert(std::is_nothrow_constructible_v<int, IntTypeNC>);
98 static_assert(!std::is_constructible_v<std::dextents<int, 2>, std::span<IntTypeNC, 2>>);
99 return 0;
100 }
101