87 lines · cpp
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-exception6//7//===----------------------------------------------------------------------===//8 9// UNSUPPORTED: c++03, c++11, c++14, c++1710 11// constexpr V base() const & requires copy_constructible<V> { return base_; }12// constexpr V base() && { return std::move(base_); }13 14#include <cassert>15#include <ranges>16#include <type_traits>17#include <utility>18 19#include "MoveOnly.h"20 21struct View : std::ranges::view_base {22 int i;23 int* begin() const;24 int* end() const;25};26 27struct MoveOnlyView : View {28 MoveOnly mo;29};30 31template <class T>32concept HasBase = requires(T&& t) { std::forward<T>(t).base(); };33 34struct Pred {35 constexpr bool operator()(int i) const { return i > 5; }36};37 38static_assert(HasBase<std::ranges::drop_while_view<View, Pred> const&>);39static_assert(HasBase<std::ranges::drop_while_view<View, Pred>&&>);40 41static_assert(!HasBase<std::ranges::drop_while_view<MoveOnlyView, Pred> const&>);42static_assert(HasBase<std::ranges::drop_while_view<MoveOnlyView, Pred>&&>);43 44constexpr bool test() {45 // const &46 {47 const std::ranges::drop_while_view<View, Pred> dwv{View{{}, 5}, {}};48 std::same_as<View> decltype(auto) v = dwv.base();49 assert(v.i == 5);50 }51 52 // &53 {54 std::ranges::drop_while_view<View, Pred> dwv{View{{}, 5}, {}};55 std::same_as<View> decltype(auto) v = dwv.base();56 assert(v.i == 5);57 }58 59 // &&60 {61 std::ranges::drop_while_view<View, Pred> dwv{View{{}, 5}, {}};62 std::same_as<View> decltype(auto) v = std::move(dwv).base();63 assert(v.i == 5);64 }65 66 // const &&67 {68 const std::ranges::drop_while_view<View, Pred> dwv{View{{}, 5}, {}};69 std::same_as<View> decltype(auto) v = std::move(dwv).base();70 assert(v.i == 5);71 }72 73 // move only74 {75 std::ranges::drop_while_view<MoveOnlyView, Pred> dwv{MoveOnlyView{{}, 5}, {}};76 std::same_as<MoveOnlyView> decltype(auto) v = std::move(dwv).base();77 assert(v.mo.get() == 5);78 }79 return true;80}81 82int main(int, char**) {83 test();84 static_assert(test());85 return 0;86}87