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 const Pred& pred() const;
12
13 #include <cassert>
14 #include <ranges>
15 #include <type_traits>
16 #include <utility>
17
18 struct View : std::ranges::view_interface<View> {
19 int* begin() const;
20 int* end() const;
21 };
22
23 struct Pred {
24 int i;
25 bool operator()(int) const;
26 };
27
test()28 constexpr bool test() {
29 // &
30 {
31 std::ranges::take_while_view<View, Pred> twv{{}, Pred{5}};
32 decltype(auto) x = twv.pred();
33 static_assert(std::same_as<decltype(x), Pred const&>);
34 assert(x.i == 5);
35 }
36
37 // const &
38 {
39 const std::ranges::take_while_view<View, Pred> twv{{}, Pred{5}};
40 decltype(auto) x = twv.pred();
41 static_assert(std::same_as<decltype(x), Pred const&>);
42 assert(x.i == 5);
43 }
44
45 // &&
46 {
47 std::ranges::take_while_view<View, Pred> twv{{}, Pred{5}};
48 decltype(auto) x = std::move(twv).pred();
49 static_assert(std::same_as<decltype(x), Pred const&>);
50 assert(x.i == 5);
51 }
52
53 // const &&
54 {
55 const std::ranges::take_while_view<View, Pred> twv{{}, Pred{5}};
56 decltype(auto) x = std::move(twv).pred();
57 static_assert(std::same_as<decltype(x), Pred const&>);
58 assert(x.i == 5);
59 }
60
61 return true;
62 }
63
main(int,char **)64 int main(int, char**) {
65 test();
66 static_assert(test());
67 return 0;
68 }
69