69 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 const Pred& pred() const;12 13#include <cassert>14#include <ranges>15#include <type_traits>16#include <utility>17 18struct View : std::ranges::view_interface<View> {19 int* begin() const;20 int* end() const;21};22 23struct Pred {24 int i;25 bool operator()(int) const;26};27 28constexpr 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 64int main(int, char**) {65 test();66 static_assert(test());67 return 0;68}69