libstdc++-v3/testsuite/20_util/is_nothrow_constructible/94003.cc

   1 // Copyright (C) 2020-2023 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   7 // any later version.
   8
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13
  14 // You should have received a copy of the GNU General Public License along
  15 // with this library; see the file COPYING3.  If not see
  16 // <http://www.gnu.org/licenses/>.
  17
  18 // { dg-do compile { target c++17 } }
  19
  20 #include <optional>
  21 #include <tuple>
  22
  23 template <bool B> struct abc {};
  24
  25 template <typename T>
  26
  27 struct future : public abc<std::is_trivially_constructible_v<std::tuple<T>>> {};
  28
  29 class mutation {
  30   mutation();
  31   friend class std::optional<mutation>;
  32 };
  33
  34 using mutation_opt = std::optional<mutation>;
  35
  36 future<mutation_opt> foo();
  37
  38 template <typename Consumer> future<mutation_opt> consume_partitions() {
  39   return foo();
  40 }
  41
  42 future<mutation_opt> bar() { return consume_partitions<int>(); }
  43
  44 future<mutation> zed();
  45 future<mutation> apply_counter_update() { return zed(); }