libstdc++-v3/testsuite/20_util/optional/swap/2.cc

   1 // { dg-options "-std=gnu++17" }
   2 // { dg-do compile { target c++17 }  }
   3
   4 // Copyright (C) 2016-2021 Free Software Foundation, Inc.
   5 //
   6 // This file is part of the GNU ISO C++ Library.  This library is free
   7 // software; you can redistribute it and/or modify it under the
   8 // terms of the GNU General Public License as published by the
   9 // Free Software Foundation; either version 3, or (at your option)
  10 // any later version.
  11
  12 // This library is distributed in the hope that it will be useful,
  13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 // GNU General Public License for more details.
  16
  17 // You should have received a copy of the GNU General Public License along
  18 // with this library; see the file COPYING3.  If not see
  19 // <http://www.gnu.org/licenses/>.
  20
  21 #include <optional>
  22
  23 // Swappable.
  24 struct A { };
  25
  26 static_assert( std::is_nothrow_swappable_v<A> );
  27 static_assert( std::is_nothrow_swappable_v<std::optional<A>> );
  28
  29 // Swappable, but might throw.
  30 struct B { };
  31 void swap(B&, B&) noexcept(false);
  32
  33 static_assert( std::is_swappable_v<std::optional<B>> );
  34 static_assert( !std::is_nothrow_swappable_v<std::optional<B>> );
  35
  36 // Not swappable, and optional<C> not swappable via the generic std::swap.
  37 struct C { };
  38 void swap(C&, C&) = delete;
  39
  40 static_assert( !std::is_swappable_v<std::optional<C>> );
  41
  42 // Not swappable, and optional<D> not swappable via the generic std::swap.
  43 struct D { D(D&&) = delete; };
  44
  45 static_assert( !std::is_swappable_v<std::optional<D>> );