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// drop_while_view() requires default_initializable<V> && default_initializable<Pred> = default;
12
13#include <cassert>
14#include <ranges>
15#include <type_traits>
16
17template <bool DefaultInitializable>
18struct View : std::ranges::view_base {
19 int i = 42;
20 constexpr explicit View()
21 requires DefaultInitializable
22 = default;
23 int* begin() const;
24 int* end() const;
25};
26
27template <bool DefaultInitializable>
28struct Pred {
29 int i = 42;
30 constexpr explicit Pred()
31 requires DefaultInitializable
32 = default;
33 bool operator()(int) const;
34};
35
36// clang-format off
37static_assert( std::is_default_constructible_v<std::ranges::drop_while_view<View<true >, Pred<true >>>);
38static_assert(!std::is_default_constructible_v<std::ranges::drop_while_view<View<false>, Pred<true >>>);
39static_assert(!std::is_default_constructible_v<std::ranges::drop_while_view<View<true >, Pred<false>>>);
40static_assert(!std::is_default_constructible_v<std::ranges::drop_while_view<View<false>, Pred<false>>>);
41// clang-format on
42
43constexpr bool test() {
44 {
45 std::ranges::drop_while_view<View<true>, Pred<true>> dwv = {};
46 assert(dwv.base().i == 42);
47 assert(dwv.pred().i == 42);
48 }
49 return true;
50}
51
52int main(int, char**) {
53 test();
54 static_assert(test());
55 return 0;
56}
57

source code of libcxx/test/std/ranges/range.adaptors/range.drop.while/ctor.default.pass.cpp