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 // UNSUPPORTED: libcpp-has-no-incomplete-ranges
11 
12 // <ranges>
13 
14 //  template<class T> struct tuple_size;
15 //  template<size_t I, class T> struct tuple_element;
16 
17 #include <ranges>
18 // Note: make sure to not include `<utility>` (or any other header including `<utility>`) because it also makes some
19 // tuple specializations available, thus obscuring whether the `<ranges>` includes work correctly.
20 
21 using Iterator = int*;
22 
23 class SizedSentinel {
24 public:
25     constexpr bool operator==(int*) const;
26     friend constexpr ptrdiff_t operator-(const SizedSentinel&, int*);
27     friend constexpr ptrdiff_t operator-(int*, const SizedSentinel&);
28 };
29 
30 static_assert(std::sized_sentinel_for<SizedSentinel, Iterator>);
31 using SizedRange = std::ranges::subrange<Iterator, SizedSentinel>;
32 
33 using UnsizedSentinel = std::unreachable_sentinel_t;
34 static_assert(!std::sized_sentinel_for<UnsizedSentinel, Iterator>);
35 using UnsizedRange = std::ranges::subrange<Iterator, UnsizedSentinel>;
36 
37 // Because the sentinel is unsized while the subrange is sized, an additional integer member will be used to store the
38 // size -- make sure it doesn't affect the value of `tuple_size`.
39 using ThreeElementRange = std::ranges::subrange<Iterator, UnsizedSentinel, std::ranges::subrange_kind::sized>;
40 static_assert(std::ranges::sized_range<ThreeElementRange>);
41 
42 static_assert(std::tuple_size<SizedRange>::value == 2);
43 static_assert(std::tuple_size<UnsizedRange>::value == 2);
44 static_assert(std::tuple_size<ThreeElementRange>::value == 2);
45 
46 template <int I, class Range, class Expected>
47 constexpr bool test_tuple_element() {
48   static_assert(std::same_as<typename std::tuple_element<I, Range>::type, Expected>);
49   static_assert(std::same_as<typename std::tuple_element<I, const Range>::type, Expected>);
50   // Note: the Standard does not mandate a specialization of `tuple_element` for volatile, so trying a `volatile Range`
51   // would fail to compile.
52 
53   return true;
54 }
55 
56 int main(int, char**) {
57   static_assert(test_tuple_element<0, SizedRange, Iterator>());
58   static_assert(test_tuple_element<1, SizedRange, SizedSentinel>());
59   static_assert(test_tuple_element<0, UnsizedRange, Iterator>());
60   static_assert(test_tuple_element<1, UnsizedRange, UnsizedSentinel>());
61 
62   return 0;
63 }
64