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++03, c++11, c++14, c++17
10
11 // <ranges>
12
13 // template<class T> struct tuple_size;
14 // template<size_t I, class T> struct tuple_element;
15
16 #include <ranges>
17 // Note: make sure to not include `<utility>` (or any other header including `<utility>`) because it also makes some
18 // tuple specializations available, thus obscuring whether the `<ranges>` includes work correctly.
19
20 using Iterator = int*;
21
22 class SizedSentinel {
23 public:
24 constexpr bool operator==(int*) const;
25 friend constexpr std::ptrdiff_t operator-(const SizedSentinel&, int*);
26 friend constexpr std::ptrdiff_t operator-(int*, const SizedSentinel&);
27 };
28
29 static_assert(std::sized_sentinel_for<SizedSentinel, Iterator>);
30 using SizedRange = std::ranges::subrange<Iterator, SizedSentinel>;
31
32 using UnsizedSentinel = std::unreachable_sentinel_t;
33 static_assert(!std::sized_sentinel_for<UnsizedSentinel, Iterator>);
34 using UnsizedRange = std::ranges::subrange<Iterator, UnsizedSentinel>;
35
36 // Because the sentinel is unsized while the subrange is sized, an additional integer member will be used to store the
37 // size -- make sure it doesn't affect the value of `tuple_size`.
38 using ThreeElementRange = std::ranges::subrange<Iterator, UnsizedSentinel, std::ranges::subrange_kind::sized>;
39 static_assert(std::ranges::sized_range<ThreeElementRange>);
40
41 static_assert(std::tuple_size<SizedRange>::value == 2);
42 static_assert(std::tuple_size<UnsizedRange>::value == 2);
43 static_assert(std::tuple_size<ThreeElementRange>::value == 2);
44
45 template <int I, class Range, class Expected>
test_tuple_element()46 constexpr bool test_tuple_element() {
47 static_assert(std::same_as<typename std::tuple_element<I, Range>::type, Expected>);
48 static_assert(std::same_as<typename std::tuple_element<I, const Range>::type, Expected>);
49 // Note: the Standard does not mandate a specialization of `tuple_element` for volatile, so trying a `volatile Range`
50 // would fail to compile.
51
52 return true;
53 }
54
main(int,char **)55 int main(int, char**) {
56 static_assert(test_tuple_element<0, SizedRange, Iterator>());
57 static_assert(test_tuple_element<1, SizedRange, SizedSentinel>());
58 static_assert(test_tuple_element<0, UnsizedRange, Iterator>());
59 static_assert(test_tuple_element<1, UnsizedRange, UnsizedSentinel>());
60
61 return 0;
62 }
63