1 // { dg-options "-std=gnu++17" } 2 // { dg-do run } 3 4 // Copyright (C) 2013-2018 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 #include <testsuite_hooks.h> 23 main()24int main() 25 { 26 // [20.5.6] Disengaged state indicator 27 static_assert( std::is_same<decltype(std::nullopt), const std::nullopt_t>(), "" ); 28 static_assert( std::is_empty<std::nullopt_t>(), "" ); 29 static_assert( std::is_literal_type<std::nullopt_t>(), "" ); 30 static_assert( !std::is_default_constructible<std::nullopt_t>(), "" ); 31 32 { 33 std::optional<int> o = std::nullopt; 34 VERIFY( !o ); 35 } 36 37 { 38 std::optional<int> o = { std::nullopt }; 39 VERIFY( !o ); 40 } 41 42 { 43 std::optional<int> o { std::nullopt }; 44 VERIFY( !o ); 45 } 46 } 47