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 // constexpr sentinel(sentinel<!Const> s);
12 // requires Const && convertible_to<sentinel_t<V>, sentinel_t<Base>>;
13
14 #include <cassert>
15 #include <ranges>
16
17 #include "../types.h"
18 #include "test_range.h"
19
20 template <class T>
21 struct convertible_sentinel_wrapper {
22 explicit convertible_sentinel_wrapper() = default;
convertible_sentinel_wrapperconvertible_sentinel_wrapper23 constexpr convertible_sentinel_wrapper(const T& it) : it_(it) {}
24
25 template <class U>
26 requires std::convertible_to<const U&, T>
convertible_sentinel_wrapperconvertible_sentinel_wrapper27 constexpr convertible_sentinel_wrapper(const convertible_sentinel_wrapper<U>& other) : it_(other.it_) {}
28
operator ==(convertible_sentinel_wrapper const & self,const T & other)29 constexpr friend bool operator==(convertible_sentinel_wrapper const& self, const T& other) {
30 return self.it_ == other;
31 }
32 T it_;
33 };
34
35 struct ConstConvertibleView : BufferView<BufferView<int*>*> {
36 using BufferView<BufferView<int*>*>::BufferView;
37
38 using sentinel = convertible_sentinel_wrapper<BufferView<int*>*>;
39 using const_sentinel = convertible_sentinel_wrapper<const BufferView<int*>*>;
40
beginConstConvertibleView41 constexpr BufferView<int*>* begin() { return data_; }
beginConstConvertibleView42 constexpr const BufferView<int*>* begin() const { return data_; }
endConstConvertibleView43 constexpr sentinel end() { return sentinel(data_ + size_); }
endConstConvertibleView44 constexpr const_sentinel end() const { return const_sentinel(data_ + size_); }
45 };
46 static_assert(!std::ranges::common_range<ConstConvertibleView>);
47 static_assert(std::convertible_to<std::ranges::sentinel_t<ConstConvertibleView>,
48 std::ranges::sentinel_t<ConstConvertibleView const>>);
49 static_assert(!simple_view<ConstConvertibleView>);
50
test()51 constexpr bool test() {
52 int buffer[4][4] = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}, {13, 14, 15, 16}};
53 {
54 BufferView<int*> inners[] = {buffer[0], buffer[1], buffer[2]};
55 ConstConvertibleView outer(inners);
56 std::ranges::join_view jv(outer);
57 auto sent1 = jv.end();
58 std::ranges::sentinel_t<const decltype(jv)> sent2 = sent1;
59 assert(std::as_const(jv).begin() != sent2);
60 assert(std::ranges::next(std::as_const(jv).begin(), 12) == sent2);
61
62 // We cannot create a non-const sentinel from a const sentinel.
63 static_assert(!std::constructible_from<decltype(sent1), decltype(sent2)>);
64 }
65
66 {
67 // cannot create a const sentinel from a non-const sentinel if the underlying
68 // const sentinel cannot be created from the underlying non-const sentinel
69 using Inner = BufferView<int*>;
70 using ConstInconvertibleOuter =
71 BufferView<forward_iterator<const Inner*>, sentinel_wrapper<forward_iterator<const Inner*>>,
72 bidirectional_iterator<Inner*>, sentinel_wrapper<bidirectional_iterator<Inner*>>>;
73 using JoinView = std::ranges::join_view<ConstInconvertibleOuter>;
74 using sentinel_t = std::ranges::sentinel_t<JoinView>;
75 using const_sentinel_t = std::ranges::sentinel_t<const JoinView>;
76 static_assert(!std::constructible_from<sentinel_t, const_sentinel_t>);
77 static_assert(!std::constructible_from<const_sentinel_t, sentinel_t>);
78 }
79 return true;
80 }
81
main(int,char **)82 int main(int, char**) {
83 test();
84 static_assert(test());
85
86 return 0;
87 }
88