| // Copyright (C) 2020-2023 Free Software Foundation, Inc. |
| // |
| // This file is part of the GNU ISO C++ Library. This library is free |
| // software; you can redistribute it and/or modify it under the |
| // terms of the GNU General Public License as published by the |
| // Free Software Foundation; either version 3, or (at your option) |
| // any later version. |
| |
| // This library is distributed in the hope that it will be useful, |
| // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| // GNU General Public License for more details. |
| |
| // You should have received a copy of the GNU General Public License along |
| // with this library; see the file COPYING3. If not see |
| // <http://www.gnu.org/licenses/>. |
| |
| // { dg-do compile { target c++17 } } |
| |
| #include <optional> |
| #include <tuple> |
| |
| template <bool B> struct abc {}; |
| |
| template <typename T> |
| |
| struct future : public abc<std::is_trivially_constructible_v<std::tuple<T>>> {}; |
| |
| class mutation { |
| mutation(); |
| friend class std::optional<mutation>; |
| }; |
| |
| using mutation_opt = std::optional<mutation>; |
| |
| future<mutation_opt> foo(); |
| |
| template <typename Consumer> future<mutation_opt> consume_partitions() { |
| return foo(); |
| } |
| |
| future<mutation_opt> bar() { return consume_partitions<int>(); } |
| |
| future<mutation> zed(); |
| future<mutation> apply_counter_update() { return zed(); } |
